Patent Publication Number: US-9907040-B2

Title: Smart meter media access control (MAC) for single user, multiple user, multiple access, and/or MIMO wireless communications

Description:
CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS 
     The present U.S. Utility patent application claims priority pursuant to 35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No. 13/539,194, entitled “Smart meter media access control (MAC) for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed Jun. 29, 2012, pending, and scheduled subsequently to be issued as U.S. Pat. No. 9,326,238 on Apr. 26, 2016 (as indicated in an ISSUE NOTIFICATION mailed from the USPTO on Apr. 6, 2016), which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/539,352, entitled “Time division multiple access (TDMA) media access control (MAC) adapted for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed Sep. 26, 2011 and U.S. Provisional Application No. 61/539,357, entitled “Smart meter media access control (MAC) for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed Sep. 26, 2011, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes. 
     INCORPORATION BY REFERENCE 
     The following U.S. Utility patent application are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes: 
     1. U.S. Utility application Ser. No. 13/539,186, entitled “Time division multiple access (TDMA) media access control (MAC) adapted for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed concurrently on Jun. 29, 2012, now U.S. Pat. No. 8,958,398, issued on Feb. 17, 2015, which also claims priority pursuant to 35 U.S.C. § 119(e) to the following U.S. Provisional patent applications which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes:
         1.1. U.S. Provisional Application No. 61/539,352, entitled “Time division multiple access (TDMA) media access control (MAC) adapted for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed Sep. 26, 2011.   1.2. U.S. Provisional Application No. 61/539,357, entitled “Smart meter media access control (MAC) for single user, multiple user, multiple access, and/or MIMO wireless communications,” filed Sep. 26, 2011.       

     2. U.S. Provisional application Ser. No. 12/796,655, entitled “Group identification and definition within multiple user, multiple access, and/or MIMO wireless communications,” filed on Jun. 8, 2010. 
     Incorporation by Reference 
     The following IEEE standards/draft standards are hereby incorporated herein by reference in their entirety and are made part of the present U.S. Utility patent application for all purposes: 
     1. IEEE Std 802.11™—2012, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” IEEE Computer Society, Sponsored by the LAN/MAN Standards Committee, IEEE Std 802.11™-2012, (Revision of IEEE Std 802.11-2007), 2793 total pages (incl. pp. i-xcvi, 1-2695). 
     2. IEEE Std 802.11n™—2009, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; Amendment 5: Enhancements for Higher Throughput,” IEEE Computer Society, IEEE Std 802.11n™-2009, (Amendment to IEEE Std 802.11™—2007 as amended by IEEE Std 802.11k™—2008, IEEE Std 802.11r™—2008, IEEE Std 802.11y™—2008, and IEEE Std 802.11r™—2009), 536 total pages (incl. pp. i-xxxii, 1-502). 
     3. IEEE Draft P802.11-REVmb™/D12, November 2011 (Revision of IEEE Std 802.11™-2007 as amended by IEEE Std 802.11k™-2008, IEEE Std 802.11r™-2008, IEEE Std 802.11y™-2008, IEEE Std 802.11w™-2009, IEEE Std 802.11n™-2009, IEEE Std 802.11p™-2010, IEEE Std 802.11z™-2010, IEEE Std 802.11v™-2011, IEEE Std 802.11u™-2011, and IEEE Std 802.11s™-2011), “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” Prepared by the 802.11 Working Group of the LAN/MAN Standards Committee of the IEEE Computer Society, 2910 total pages (incl. pp. i-cxxviii, 1-2782). 
     4. IEEE P802.11ac™/D2.1, March 2012, “Draft STANDARD for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz,” Prepared by the 802.11 Working Group of the 802 Committee, 363 total pages (incl. pp. i-xxv, 1-338). 
     5. IEEE P802.11ad™/D6.0, March 2012, (Draft Amendment based on IEEE P802.11REVmb D12.0), (Amendment to IEEE P802.11REVmb D12.0 as amended by IEEE 802.11ae D8.0 and IEEE 802.11aa D9.0), “IEEE P802.11ad™/D6.0 Draft Standard for Information Technology—Telecommunications and Information Exchange Between Systems—Local and Metropolitan Area Networks—Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications—Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band,” Sponsor: IEEE 802.11 Committee of the IEEE Computer Society, IEEE-SA Standards Board, 664 total pages. 
     6. IEEE Std 802.11 ae™—2012, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” “Amendment 1: Prioritization of Management Frames,” IEEE Computer Society, Sponsored by the LAN/MAN Standards Committee, IEEE Std 802.11ae™-2012, (Amendment to IEEE Std 802.11™-2012), 52 total pages (incl. pp. i-xii, 1-38). 
     7. IEEE P802.11af™/D1.06, March 2012, (Amendment to IEEE Std 802.11REVmb™/D12.0 as amended by IEEE Std 802.11ae™/D8.0, IEEE Std 802.11aa™/D9.0, IEEE Std 802.11ad™/D5.0, and IEEE Std 802.11ac™/D2.0), “Draft Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications—Amendment 5: TV White Spaces Operation,” Prepared by the 802.11 Working Group of the IEEE 802 Committee, 140 total pages (incl. pp. i-xxii, 1-118). 
    
    
     BACKGROUND OF THE INVENTION 
     Technical Field of the Invention 
     The invention relates generally to communication systems; and, more particularly, it relates to coordination and operation of multiple wireless communication devices within single user, multiple user, multiple access, and/or MIMO wireless communications. 
     Description of Related Art 
     Communication systems are known to support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11x, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof. 
     Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc., communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the participating wireless communication devices tune their receivers and transmitters to the same channel or channels (e.g., one of the plurality of radio frequency (RF) carriers of the wireless communication system) and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station (e.g., for cellular services) and/or an associated access point (e.g., for an in-home or in-building wireless network) via an assigned channel. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via the public switch telephone network, via the Internet, and/or via some other wide area network. 
     For each wireless communication device to participate in wireless communications, it includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the receiver is coupled to the antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage, and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The one or more intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard. 
     As is also known, the transmitter includes a data modulation stage, one or more intermediate frequency stages, and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna. 
     Typically, the transmitter will include one antenna for transmitting the RF signals, which are received by a single antenna, or multiple antennae (alternatively, antennas), of a receiver. When the receiver includes two or more antennae, the receiver will select one of them to receive the incoming RF signals. In this instance, the wireless communication between the transmitter and receiver is a single-output-single-input (SISO) communication, even if the receiver includes multiple antennae that are used as diversity antennae (i.e., selecting one of them to receive the incoming RF signals). For SISO wireless communications, a transceiver includes one transmitter and one receiver. Currently, most wireless local area networks (WLAN) that are IEEE 802.11, 802.11a, 802.11b, or 802.11g employ SISO wireless communications. 
     Other types of wireless communications include single-input-multiple-output (SIMO), multiple-input-single-output (MISO), and multiple-input-multiple-output (MIMO). In a SIMO wireless communication, a single transmitter processes data into radio frequency signals that are transmitted to a receiver. The receiver includes two or more antennae and two or more receiver paths. Each of the antennae receives the RF signals and provides them to a corresponding receiver path (e.g., LNA, down conversion module, filters, and ADCs). Each of the receiver paths processes the received RF signals to produce digital signals, which are combined and then processed to recapture the transmitted data. 
     For a multiple-input-single-output (MISO) wireless communication, the transmitter includes two or more transmission paths (e.g., digital to analog converter, filters, up-conversion module, and a power amplifier) that each converts a corresponding portion of baseband signals into RF signals, which are transmitted via corresponding antennae to a receiver. The receiver includes a single receiver path that receives the multiple RF signals from the transmitter. In this instance, the receiver uses beam forming to combine the multiple RF signals into one signal for processing. 
     For a multiple-input-multiple-output (MIMO) wireless communication, the transmitter and receiver each include multiple paths. In such a communication, the transmitter parallel processes data using a spatial and time encoding function to produce two or more streams of data. The transmitter includes multiple transmission paths to convert each stream of data into multiple RF signals. The receiver receives the multiple RF signals via multiple receiver paths that recapture the streams of data utilizing a spatial and time decoding function. The recaptured streams of data are combined and subsequently processed to recover the original data. 
     With the various types of wireless communications (e.g., SISO, MISO, SIMO, and MIMO), it would be desirable to use one or more types of wireless communications to enhance data throughput within a WLAN. For example, high data rates can be achieved with MIMO communications in comparison to SISO communications. However, most WLAN include legacy wireless communication devices (i.e., devices that are compliant with an older version of a wireless communication standard). As such, a transmitter capable of MIMO wireless communications should also be backward compatible with legacy devices to function in a majority of existing WLANs. 
     Therefore, a need exists for a WLAN device that is capable of high data throughput and is backward compatible with legacy devices. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an embodiment of a wireless communication system. 
         FIG. 2  is a diagram illustrating an embodiment of a wireless communication device. 
         FIG. 3  is a diagram illustrating an embodiment of a radio frequency (RF) transmitter. 
         FIG. 4  is a diagram illustrating an embodiment of an RF receiver. 
         FIG. 5  is a diagram illustrating an embodiment of a method for baseband processing of data. 
         FIG. 6  is a diagram illustrating an embodiment of a method that further defines Step  120  of  FIG. 5 . 
         FIGS. 7-9  are diagrams illustrating various embodiments for encoding the scrambled data. 
         FIGS. 10A and 10B  are diagrams illustrating embodiments of a radio transmitter. 
         FIGS. 11A and 11B  are diagrams illustrating embodiments of a radio receiver. 
         FIG. 12  is a diagram illustrating an embodiment of an access point (AP) and multiple wireless local area network (WLAN) devices operating according to one or more various aspects and/or embodiments of the invention. 
         FIG. 13  is a diagram illustrating an embodiment of a wireless communication device, and clusters, as may be employed for supporting communications with at least one additional wireless communication device. 
         FIG. 14  illustrates an embodiment of a number of wireless communication devices implemented in various locations in an environment including a building or structure. 
         FIG. 15  illustrates an embodiment of a number of wireless communication devices implemented in various locations in a vehicular environment. 
         FIG. 16  illustrates an embodiment of a number of wireless communication devices implemented in various locations throughout a broadly distributed industrial environment. 
         FIG. 17  illustrates an embodiment of a wireless communication system including a number of wireless communication devices therein. 
         FIG. 18  illustrates an alternative embodiment of a wireless communication system including a number of wireless communication devices therein. 
         FIG. 19  illustrates an embodiment of time division multiple access (TDMA) operation, as may be effectuated at a media access control (MAC) layer, within various wireless communication devices. 
         FIG. 20  illustrates an embodiment of TDMA operation on multiple, respective frequencies, spectra thereof, channels, and/or clusters, as may be effectuated at a MAC layer, within various wireless communication devices. 
         FIG. 21  illustrates an embodiment of multiple service periods (SPs) for use in various wireless communication devices within a wireless communication system. 
         FIG. 22  illustrates an alternative embodiment of multiple SPs for use in various wireless communication devices within a wireless communication system. 
         FIG. 23  illustrates an embodiment of TDMA termination for various wireless communication devices within a wireless communication system. 
         FIG. 24  illustrates an embodiment of a smart meter station (SMSTA) entering a sleep period for a period of time and awakening for a subsequent data transmission. 
         FIG. 25  illustrates an embodiment of a multiple respective wakeup windows, being distributed over time, corresponding to a number of respective SMSTAs. 
         FIG. 26  illustrates an embodiment of one wireless communication device (e.g., an access point (AP), or a wireless station (STA) operating as an AP, etc.) providing medium control during respective wakeup windows. 
         FIG. 27  illustrates an embodiment of respective communications between wireless communication devices in a wireless communication system. 
         FIG. 28  illustrates an embodiment of transmission retry of a SMSTA to another wireless communication device. 
         FIG. 29  illustrates an alternative embodiment of transmission retry of a SMSTA to another wireless communication device. 
         FIG. 30  illustrates an embodiment of one wireless communication device (e.g., an AP, or a STA operating as an AP, etc.) providing medium control in accordance with polling frames to a number of wireless communication devices (e.g., SMSTAs). 
         FIG. 31  illustrates an embodiment of synchronization (e.g., of clocks) of a number of wireless communication devices (e.g., SMSTAs). 
         FIG. 32 ,  FIG. 33A ,  FIG. 33B , and  FIG. 34  illustrate various embodiments of methods performed by one or more communication devices. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a diagram illustrating an embodiment of a wireless communication system  10  that includes a plurality of base stations and/or access points  12 - 16 , a plurality of wireless communication devices  18 - 32  and a network hardware component  34 . The wireless communication devices  18 - 32  may be laptop host computers  18  and  26 , personal digital assistant hosts  20  and  30 , personal computer hosts  24  and  32  and/or cellular telephone hosts  22  and  28 . The details of an embodiment of such wireless communication devices are described in greater detail with reference to  FIG. 2 . 
     The base stations (BSs) or access points (APs)  12 - 16  are operably coupled to the network hardware  34  via local area network connections  36 ,  38  and  40 . The network hardware  34 , which may be a router, switch, bridge, modem, system controller, etc., provides a wide area network connection  42  for the communication system  10 . Each of the base stations or access points  12 - 16  has an associated antenna or antenna array to communicate with the wireless communication devices in its area. Typically, the wireless communication devices register with a particular base station or access point  12 - 14  to receive services from the communication system  10 . For direct connections (i.e., point-to-point communications), wireless communication devices communicate directly via an allocated channel. 
     Typically, base stations are used for cellular telephone systems (e.g., advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), Enhanced Data rates for GSM Evolution (EDGE), General Packet Radio Service (GPRS), high-speed downlink packet access (HSDPA), high-speed uplink packet access (HSDPA and/or variations thereof) and like-type systems, while access points are used for in-home or in-building wireless networks (e.g., IEEE 802.11, Bluetooth, ZigBee, any other type of radio frequency based network protocol and/or variations thereof). Regardless of the particular type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. Such wireless communication devices may operate in accordance with the various aspects of the invention as presented herein to enhance performance, reduce costs, reduce size, and/or enhance broadband applications. 
       FIG. 2  is a diagram illustrating an embodiment of a wireless communication device that includes the host device  18 - 32  and an associated radio  60 . For cellular telephone hosts, the radio  60  is a built-in component. For personal digital assistants hosts, laptop hosts, and/or personal computer hosts, the radio  60  may be built-in or an externally coupled component. For access points or base stations, the components are typically housed in a single structure. 
     As illustrated, the host device  18 - 32  includes a processing module  50 , memory  52 , radio interface  54 , input interface  58  and output interface  56 . The processing module  50  and memory  52  execute the corresponding instructions that are typically done by the host device. For example, for a cellular telephone host device, the processing module  50  performs the corresponding communication functions in accordance with a particular cellular telephone standard. 
     The radio interface  54  allows data to be received from and sent to the radio  60 . For data received from the radio  60  (e.g., inbound data), the radio interface  54  provides the data to the processing module  50  for further processing and/or routing to the output interface  56 . The output interface  56  provides connectivity to an output display device such as a display, monitor, speakers, etc. such that the received data may be displayed. The radio interface  54  also provides data from the processing module  50  to the radio  60 . The processing module  50  may receive the outbound data from an input device such as a keyboard, keypad, microphone, etc. via the input interface  58  or generate the data itself. For data received via the input interface  58 , the processing module  50  may perform a corresponding host function on the data and/or route it to the radio  60  via the radio interface  54 . 
     Radio  60  includes a host interface  62 , a baseband processing module  64 , memory  66 , a plurality of radio frequency (RF) transmitters  68 - 72 , a transmit/receive (T/R) module  74 , a plurality of antennae  82 - 86 , a plurality of RF receivers  76 - 80 , and a local oscillation module  100 . The baseband processing module  64 , in combination with operational instructions stored in memory  66 , execute digital receiver functions and digital transmitter functions, respectively. The digital receiver functions, as will be described in greater detail with reference to  FIG. 11B , include, but are not limited to, digital intermediate frequency to baseband conversion, demodulation, constellation demapping, decoding, de-interleaving, fast Fourier transform, cyclic prefix removal, space and time decoding, and/or descrambling. The digital transmitter functions, as will be described in greater detail with reference to later Figures, include, but are not limited to, scrambling, encoding, interleaving, constellation mapping, modulation, inverse fast Fourier transform, cyclic prefix addition, space and time encoding, and/or digital baseband to IF conversion. The baseband processing modules  64  may be implemented using one or more processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory  66  may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module  64  implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory storing the corresponding operational instructions is embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. 
     In operation, the radio  60  receives outbound data  88  from the host device via the host interface  62 . The baseband processing module  64  receives the outbound data  88  and, based on a mode selection signal  102 , produces one or more outbound symbol streams  90 . The mode selection signal  102  will indicate a particular mode as are illustrated in the mode selection tables, which appear at the end of the detailed discussion. For example, the mode selection signal  102 , with reference to table 1 may indicate a frequency band of 2.4 GHz or 5 GHz, a channel bandwidth of 20 or 22 MHz (e.g., channels of 20 or 22 MHz width) and a maximum bit rate of 54 megabits-per-second. In other embodiments, the channel bandwidth may extend up to 1.28 GHz or wider with supported maximum bit rates extending to 1 gigabit-per-second or greater. In this general category, the mode selection signal will further indicate a particular rate ranging from 1 megabit-per-second to 54 megabits-per-second. In addition, the mode selection signal will indicate a particular type of modulation, which includes, but is not limited to, Barker Code Modulation, BPSK, QPSK, CCK, 16 QAM and/or 64 QAM. As is further illustrated in table 1, a code rate is supplied as well as number of coded bits per subcarrier (NBPSC), coded bits per OFDM symbol (NCBPS), data bits per OFDM symbol (NDBPS). 
     The mode selection signal may also indicate a particular channelization for the corresponding mode which for the information in table 1 is illustrated in table 2. As shown, table 2 includes a channel number and corresponding center frequency. The mode select signal may further indicate a power spectral density mask value which for table 1 is illustrated in table 3. The mode select signal may alternatively indicate rates within table 4 that has a 5 GHz frequency band, 20 MHz channel bandwidth and a maximum bit rate of 54 megabits-per-second. If this is the particular mode select, the channelization is illustrated in table 5. As a further alternative, the mode select signal  102  may indicate a 2.4 GHz frequency band, 20 MHz channels and a maximum bit rate of 192 megabits-per-second as illustrated in table 6. In table 6, a number of antennae may be utilized to achieve the higher bit rates. In this instance, the mode select would further indicate the number of antennae to be utilized. Table 7 illustrates the channelization for the set-up of table 6. Table 8 illustrates yet another mode option where the frequency band is 2.4 GHz, the channel bandwidth is 20 MHz and the maximum bit rate is 192 megabits-per-second. The corresponding table 8 includes various bit rates ranging from 12 megabits-per-second to 216 megabits-per-second utilizing 2-4 antennae and a spatial time encoding rate as indicated. Table 9 illustrates the channelization for table 8. The mode select signal  102  may further indicate a particular operating mode as illustrated in table 10, which corresponds to a 5 GHz frequency band having 40 MHz frequency band having 40 MHz channels and a maximum bit rate of 486 megabits-per-second. As shown in table 10, the bit rate may range from 13.5 megabits-per-second to 486 megabits-per-second utilizing 1-4 antennae and a corresponding spatial time code rate. Table 10 further illustrates a particular modulation scheme code rate and NBPSC values. Table 11 provides the power spectral density mask for table 10 and table 12 provides the channelization for table 10. 
     It is of course noted that other types of channels, having different bandwidths, may be employed in other embodiments without departing from the scope and spirit of the invention. For example, various other channels such as those having 80 MHz, 120 MHz, and/or 160 MHz of bandwidth may alternatively be employed such as in accordance with IEEE Task Group ac (TGac VHTL6). 
     The baseband processing module  64 , based on the mode selection signal  102  produces the one or more outbound symbol streams  90 , as will be further described with reference to  FIGS. 5-9  from the output data  88 . For example, if the mode selection signal  102  indicates that a single transmit antenna is being utilized for the particular mode that has been selected, the baseband processing module  64  will produce a single outbound symbol stream  90 . Alternatively, if the mode select signal indicates 2, 3 or 4 antennae, the baseband processing module  64  will produce 2, 3 or 4 outbound symbol streams  90  corresponding to the number of antennae from the output data  88 . 
     Depending on the number of outbound streams  90  produced by the baseband module  64 , a corresponding number of the RF transmitters  68 - 72  will be enabled to convert the outbound symbol streams  90  into outbound RF signals  92 . The implementation of the RF transmitters  68 - 72  will be further described with reference to  FIG. 3 . The transmit/receive module  74  receives the outbound RF signals  92  and provides each outbound RF signal to a corresponding antenna  82 - 86 . 
     When the radio  60  is in the receive mode, the transmit/receive module  74  receives one or more inbound RF signals via the antennae  82 - 86 . The T/R module  74  provides the inbound RF signals  94  to one or more RF receivers  76 - 80 . The RF receiver  76 - 80 , which will be described in greater detail with reference to  FIG. 4 , converts the inbound RF signals  94  into a corresponding number of inbound symbol streams  96 . The number of inbound symbol streams  96  will correspond to the particular mode in which the data was received (recall that the mode may be any one of the modes illustrated in tables 1-12). The baseband processing module  64  receives the inbound symbol streams  90  and converts them into inbound data  98 , which is provided to the host device  18 - 32  via the host interface  62 . 
     In one embodiment of radio  60  it includes a transmitter and a receiver. The transmitter may include a MAC module, a PLCP module, and a PMD module. The Medium Access Control (MAC) module, which may be implemented with the processing module  64 , is operably coupled to convert a MAC Service Data Unit (MSDU) into a MAC Protocol Data Unit (MPDU) in accordance with a WLAN protocol. The Physical Layer Convergence Procedure (PLCP) Module, which may be implemented in the processing module  64 , is operably coupled to convert the MPDU into a PLCP Protocol Data Unit (PPDU) in accordance with the WLAN protocol. The Physical Medium Dependent (PMD) module is operably coupled to convert the PPDU into a plurality of radio frequency (RF) signals in accordance with one of a plurality of operating modes of the WLAN protocol, wherein the plurality of operating modes includes multiple input and multiple output combinations. 
     An embodiment of the Physical Medium Dependent (PMD) module, which will be described in greater detail with reference to  FIGS. 10A and 10B , includes an error protection module, a demultiplexing module, and a plurality of direction conversion modules. The error protection module, which may be implemented in the processing module  64 , is operably coupled to restructure a PPDU (PLCP (Physical Layer Convergence Procedure) Protocol Data Unit) to reduce transmission errors producing error protected data. The demultiplexing module is operably coupled to divide the error protected data into a plurality of error protected data streams The plurality of direct conversion modules is operably coupled to convert the plurality of error protected data streams into a plurality of radio frequency (RF) signals. 
     As one of average skill in the art will appreciate, the wireless communication device of  FIG. 2  may be implemented using one or more integrated circuits. For example, the host device may be implemented on one integrated circuit, the baseband processing module  64  and memory  66  may be implemented on a second integrated circuit, and the remaining components of the radio  60 , less the antennae  82 - 86 , may be implemented on a third integrated circuit. As an alternate example, the radio  60  may be implemented on a single integrated circuit. As yet another example, the processing module  50  of the host device and the baseband processing module  64  may be a common processing device implemented on a single integrated circuit. Further, the memory  52  and memory  66  may be implemented on a single integrated circuit and/or on the same integrated circuit as the common processing modules of processing module  50  and the baseband processing module  64 . 
       FIG. 3  is a diagram illustrating an embodiment of a radio frequency (RF) transmitter  68 - 72 , or RF front-end, of the WLAN transmitter. The RF transmitter  68 - 72  includes a digital filter and up-sampling module  75 , a digital-to-analog conversion module  77 , an analog filter  79 , and up-conversion module  81 , a power amplifier  83  and a RF filter  85 . The digital filter and up-sampling module  75  receives one of the outbound symbol streams  90  and digitally filters it and then up-samples the rate of the symbol streams to a desired rate to produce the filtered symbol streams  87 . The digital-to-analog conversion module  77  converts the filtered symbols  87  into analog signals  89 . The analog signals may include an in-phase component and a quadrature component. 
     The analog filter  79  filters the analog signals  89  to produce filtered analog signals  91 . The up-conversion module  81 , which may include a pair of mixers and a filter, mixes the filtered analog signals  91  with a local oscillation  93 , which is produced by local oscillation module  100 , to produce high frequency signals  95 . The frequency of the high frequency signals  95  corresponds to the frequency of the outbound RF signals  92 . 
     The power amplifier  83  amplifies the high frequency signals  95  to produce amplified high frequency signals  97 . The RF filter  85 , which may be a high frequency band-pass filter, filters the amplified high frequency signals  97  to produce the desired output RF signals  92 . 
     As one of average skill in the art will appreciate, each of the radio frequency transmitters  68 - 72  will include a similar architecture as illustrated in  FIG. 3  and further include a shut-down mechanism such that when the particular radio frequency transmitter is not required, it is disabled in such a manner that it does not produce interfering signals and/or noise. 
       FIG. 4  is a diagram illustrating an embodiment of an RF receiver. This may depict any one of the RF receivers  76 - 80 . In this embodiment, each of the RF receivers  76 - 80  includes an RF filter  101 , a low noise amplifier (LNA)  103 , a programmable gain amplifier (PGA)  105 , a down-conversion module  107 , an analog filter  109 , an analog-to-digital conversion module  111  and a digital filter and down-sampling module  113 . The RF filter  101 , which may be a high frequency band-pass filter, receives the inbound RF signals  94  and filters them to produce filtered inbound RF signals. The low noise amplifier  103  amplifies the filtered inbound RF signals  94  based on a gain setting  115  and provides the amplified signals to the programmable gain amplifier  105 . The programmable gain amplifier further amplifies the inbound RF signals  94  before providing them to the down-conversion module  107 . 
     The down-conversion module  107  includes a pair of mixers, a summation module, and a filter to mix the inbound RF signals with a local oscillation (LO) signal  117  that is provided by the local oscillation module  100  to produce analog baseband signals. The analog filter  109  filters the analog baseband signals and provides them to the analog-to-digital conversion module  111  which converts them into a digital signal. The digital filter and down-sampling module  113  filters the digital signals and then adjusts the sampling rate to produce the digital samples (corresponding to the inbound symbol streams  96 ). 
       FIG. 5  is a diagram illustrating an embodiment of a method for baseband processing of data. This diagram shows a method for converting outbound data  88  into one or more outbound symbol streams  90  by the baseband processing module  64 . The process begins at Step  110  where the baseband processing module receives the outbound data  88  and a mode selection signal  102 . The mode selection signal may indicate any one of the various modes of operation as indicated in tables 1-12. The process then proceeds to Step  112  where the baseband processing module scrambles the data in accordance with a pseudo random sequence to produce scrambled data. Note that the pseudo random sequence may be generated from a feedback shift register with the generator polynomial of S(x)=x 7 +x 4 +1. 
     The process then proceeds to Step  114  where the baseband processing module selects one of a plurality of encoding modes based on the mode selection signal. The process then proceeds to Step  116  where the baseband processing module encodes the scrambled data in accordance with a selected encoding mode to produce encoded data. The encoding may be done utilizing any one or more a variety of coding schemes (e.g., convolutional coding, Reed-Solomon (RS) coding, turbo coding, turbo trellis coded modulation (TTCM) coding, LDPC (Low Density Parity Check) coding, etc.). 
     The process then proceeds to Step  118  where the baseband processing module determines a number of transmit streams based on the mode select signal. For example, the mode select signal will select a particular mode which indicates that 1, 2, 3, 4 or more antennae may be utilized for the transmission. Accordingly, the number of transmit streams will correspond to the number of antennae indicated by the mode select signal. The process then proceeds to Step  120  where the baseband processing module converts the encoded data into streams of symbols in accordance with the number of transmit streams in the mode select signal. This step will be described in greater detail with reference to  FIG. 6 . 
       FIG. 6  is a diagram illustrating an embodiment of a method that further defines Step  120  of  FIG. 5 . This diagram shows a method performed by the baseband processing module to convert the encoded data into streams of symbols in accordance with the number of transmit streams and the mode select signal. Such processing begins at Step  122  where the baseband processing module interleaves the encoded data over multiple symbols and subcarriers of a channel to produce interleaved data. In general, the interleaving process is designed to spread the encoded data over multiple symbols and transmit streams. This allows improved detection and error correction capability at the receiver. In one embodiment, the interleaving process will follow the IEEE 802.11(a) or (g) standard for backward compatible modes. For higher performance modes (e.g., IEEE 802.11(n), the interleaving will also be done over multiple transmit paths or streams. 
     The process then proceeds to Step  124  where the baseband processing module demultiplexes the interleaved data into a number of parallel streams of interleaved data. The number of parallel streams corresponds to the number of transmit streams, which in turn corresponds to the number of antennae indicated by the particular mode being utilized. The process then continues to Steps  126  and  128 , where for each of the parallel streams of interleaved data, the baseband processing module maps the interleaved data into a quadrature amplitude modulated (QAM) symbol to produce frequency domain symbols at Step  126 . At Step  128 , the baseband processing module converts the frequency domain symbols into time domain symbols, which may be done utilizing an inverse fast Fourier transform. The conversion of the frequency domain symbols into the time domain symbols may further include adding a cyclic prefix to allow removal of intersymbol interference at the receiver. Note that the length of the inverse fast Fourier transform and cyclic prefix are defined in the mode tables of tables 1-12. In general, a 64-point inverse fast Fourier transform is employed for 20 MHz channels and 128-point inverse fast Fourier transform is employed for 40 MHz channels. 
     The process then proceeds to Step  130  where the baseband processing module space and time encodes the time domain symbols for each of the parallel streams of interleaved data to produce the streams of symbols. In one embodiment, the space and time encoding may be done by space and time encoding the time domain symbols of the parallel streams of interleaved data into a corresponding number of streams of symbols utilizing an encoding matrix. Alternatively, the space and time encoding may be done by space and time encoding the time domain symbols of M-parallel streams of interleaved data into P-streams of symbols utilizing the encoding matrix, where P=2M In one embodiment the encoding matrix may comprise a form of: 
               [           C   1           C   2           C   3           C   4         …         C       2   ⁢   M     -   1             C     2   ⁢   M                 -     C   2   *             C   1   *           -     C   4   *             C   3   *         …         -     C     2   ⁢   M     *             C       2   ⁢   M     -   1             ]               
The number of rows of the encoding matrix corresponds to M and the number of columns of the encoding matrix corresponds to P. The particular symbol values of the constants within the encoding matrix may be real or imaginary numbers.
 
       FIGS. 7-9  are diagrams illustrating various embodiments for encoding the scrambled data. 
       FIG. 7  is a diagram of one method that may be utilized by the baseband processing module to encode the scrambled data at Step  116  of  FIG. 5 . In this method, the encoding of  FIG. 7  may include an optional Step  144  where the baseband processing module may optionally perform encoding with an outer Reed-Solomon (RS) code to produce RS encoded data. It is noted that Step  144  may be conducted in parallel with Step  140  described below. 
     Also, the process continues at Step  140  where the baseband processing module performs a convolutional encoding with a 64 state code and generator polynomials of G 0 =133 8  and G 1 =171 8  on the scrambled data (that may or may not have undergone RS encoding) to produce convolutional encoded data. The process then proceeds to Step  142  where the baseband processing module punctures the convolutional encoded data at one of a plurality of rates in accordance with the mode selection signal to produce the encoded data. Note that the puncture rates may include ½, ⅔ and/or ¾, or any rate as specified in tables 1-12. Note that, for a particular mode, the rate may be selected for backward compatibility with IEEE 802.11(a), IEEE 802.11(g), or IEEE 802.11(n) rate requirements. 
       FIG. 8  is a diagram of another encoding method that may be utilized by the baseband processing module to encode the scrambled data at Step  116  of  FIG. 5 . In this embodiment, the encoding of  FIG. 8  may include an optional Step  148  where the baseband processing module may optionally perform encoding with an outer RS code to produce RS encoded data. It is noted that Step  148  may be conducted in parallel with Step  146  described below. 
     The method then continues at Step  146  where the baseband processing module encodes the scrambled data (that may or may not have undergone RS encoding) in accordance with a complimentary code keying (CCK) code to produce the encoded data. This may be done in accordance with IEEE 802.11(b) specifications, IEEE 802.11(g), and/or IEEE 802.11(n) specifications. 
       FIG. 9  is a diagram of yet another method for encoding the scrambled data at Step  116 , which may be performed by the baseband processing module. In this embodiment, the encoding of  FIG. 9  may include an optional Step  154  where the baseband processing module may optionally perform encoding with an outer RS code to produce RS encoded data. 
     Then, in some embodiments, the process continues at Step  150  where the baseband processing module performs LDPC (Low Density Parity Check) coding on the scrambled data (that may or may not have undergone RS encoding) to produce LDPC coded bits. Alternatively, the Step  150  may operate by performing convolutional encoding with a 256 state code and generator polynomials of G 0 =561 8  and G 1 =753 8  on the scrambled data the scrambled data (that may or may not have undergone RS encoding) to produce convolutional encoded data. The process then proceeds to Step  152  where the baseband processing module punctures the convolutional encoded data at one of the plurality of rates in accordance with a mode selection signal to produce encoded data. Note that the puncture rate is indicated in the tables 1-12 for the corresponding mode. 
     The encoding of  FIG. 9  may further include the optional Step  154  where the baseband processing module combines the convolutional encoding with an outer Reed Solomon code to produce the convolutional encoded data. 
       FIGS. 10A and 10B  are diagrams illustrating embodiments of a radio transmitter. This may involve the PMD module of a WLAN transmitter. In  FIG. 10A , the baseband processing  160  is shown to include a scrambler  172 , channel encoder  174 , interleaver  176 , demultiplexer  170 , a plurality of symbol mappers  180 - 184 , a plurality of inverse fast Fourier transform (IFFT)/cyclic prefix addition modules  186 - 190  and a space/time encoder  192 . The baseband portion of the transmitter may further include a mode manager module  175  that receives the mode selection signal  173  and produces settings  179  for the radio transmitter portion and produces the rate selection  171  for the baseband portion. In this embodiment, the scrambler  172 , the channel encoder  174 , and the interleaver  176  comprise an error protection module. The symbol mappers  180 - 184 , the plurality of IFFT/cyclic prefix modules  186 - 190 , the space time encoder  192  comprise a portion of the digital baseband processing module. 
     In operations, the scrambler  172  adds (e.g., in a Galois Finite Field (GF2)) a pseudo random sequence to the outbound data bits  88  to make the data appear random. A pseudo random sequence may be generated from a feedback shift register with the generator polynomial of S(x)=x 7 +x 4 +1 to produce scrambled data. The channel encoder  174  receives the scrambled data and generates a new sequence of bits with redundancy. This will enable improved detection at the receiver. The channel encoder  174  may operate in one of a plurality of modes. For example, for backward compatibility with IEEE 802.11(a) and IEEE 802.11(g), the channel encoder has the form of a rate ½convolutional encoder with 64 states and a generator polynomials of G 0 =133 8  and G 1 =171 8 . The output of the convolutional encoder may be punctured to rates of ½, ⅔, and ¾ according to the specified rate tables (e.g., tables 1-12). For backward compatibility with IEEE 802.11(b) and the CCK modes of IEEE 802.11(g), the channel encoder has the form of a CCK code as defined in IEEE 802.11(b). For higher data rates (such as those illustrated in tables 6, 8 and 10), the channel encoder may use the same convolution encoding as described above or it may use a more powerful code, including a convolutional code with more states, any one or more of the various types of error correction codes (ECCs) mentioned above (e.g., RS, LDPC, turbo, TTCM, etc.) a parallel concatenated (turbo) code and/or a low density parity check (LDPC) block code. Further, any one of these codes may be combined with an outer Reed Solomon code. Based on a balancing of performance, backward compatibility and low latency, one or more of these codes may be optimal. Note that the concatenated turbo encoding and low density parity check will be described in greater detail with reference to subsequent Figures. 
     The interleaver  176  receives the encoded data and spreads it over multiple symbols and transmit streams. This allows improved detection and error correction capabilities at the receiver. In one embodiment, the interleaver  176  will follow the IEEE 802.11(a) or (g) standard in the backward compatible modes. For higher performance modes (e.g., such as those illustrated in tables 6, 8 and 10), the interleaver will interleave data over multiple transmit streams. The demultiplexer  170  converts the serial interleave stream from interleaver  176  into M-parallel streams for transmission. 
     Each symbol mapper  180 - 184  receives a corresponding one of the M-parallel paths of data from the demultiplexer. Each symbol mapper  180 - 182  lock maps bit streams to quadrature amplitude modulated QAM symbols (e.g., BPSK, QPSK, 16 QAM, 64 QAM, 256 QAM, etc.) according to the rate tables (e.g., tables 1-12). For IEEE 802.11(a) backward compatibility, double Gray coding may be used. 
     The map symbols produced by each of the symbol mappers  180 - 184  are provided to the IFFT/cyclic prefix addition modules  186 - 190 , which performs frequency domain to time domain conversions and adds a prefix, which allows removal of inter-symbol interference at the receiver. Note that the length of the IFFT and cyclic prefix are defined in the mode tables of tables 1-12. In general, a 64-point IFFT will be used for 20 MHz channels and 128-point IFFT will be used for 40 MHz channels. 
     The space/time encoder  192  receives the M-parallel paths of time domain symbols and converts them into P-output symbols. In one embodiment, the number of M-input paths will equal the number of P-output paths. In another embodiment, the number of output paths P will equal 2M paths. For each of the paths, the space/time encoder multiples the input symbols with an encoding matrix that has the form of 
     
       
         
           
             
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     The rows of the encoding matrix correspond to the number of input paths and the columns correspond to the number of output paths. 
       FIG. 10B  illustrates the radio portion of the transmitter that includes a plurality of digital filter/up-sampling modules  194 - 198 , digital-to-analog conversion modules  200 - 204 , analog filters  206 - 216 , FQ modulators  218 - 222 , RF amplifiers  224 - 228 , RF filters  230 - 234  and antennae  236 - 240 . The P-outputs from the space/time encoder  192  are received by respective digital filtering/up-sampling modules  194 - 198 . In one embodiment, the digital filters/up sampling modules  194 - 198  are part of the digital baseband processing module and the remaining components comprise the plurality of RF front-ends. In such an embodiment, the digital baseband processing module and the RF front end comprise a direct conversion module. 
     In operation, the number of radio paths that are active correspond to the number of P-outputs. For example, if only one P-output path is generated, only one of the radio transmitter paths will be active. As one of average skill in the art will appreciate, the number of output paths may range from one to any desired number. 
     The digital filtering/up-sampling modules  194 - 198  filter the corresponding symbols and adjust the sampling rates to correspond with the desired sampling rates of the digital-to-analog conversion modules  200 - 204 . The digital-to-analog conversion modules  200 - 204  convert the digital filtered and up-sampled signals into corresponding in-phase and quadrature analog signals. The analog filters  206 - 214  filter the corresponding in-phase and/or quadrature components of the analog signals, and provide the filtered signals to the corresponding I/Q modulators  218 - 222 . The FQ modulators  218 - 222  based on a local oscillation, which is produced by a local oscillator (LO)  100 , up-converts the I/Q signals into radio frequency signals. 
     The RF amplifiers  224 - 228  amplify the RF signals which are then subsequently filtered via RF filters  230 - 234  before being transmitted via antennae  236 - 240 . 
       FIGS. 11A and 11B  are diagrams illustrating embodiments of a radio receiver (as shown by reference numeral  250 ). These diagrams illustrate a schematic block diagram of another embodiment of a receiver.  FIG. 11A  illustrates the analog portion of the receiver which includes a plurality of receiver paths. Each receiver path includes an antenna, RF filters  252 - 256 , low noise amplifiers  258 - 262 , I/Q demodulators  264 - 268 , analog filters  270 - 280 , analog-to-digital converters  282 - 286  and digital filters and down-sampling modules  288 - 290 . 
     In operation, the antennae receive inbound RF signals, which are band-pass filtered via the RF filters  252 - 256 . The corresponding low noise amplifiers  258 - 262  amplify the filtered signals and provide them to the corresponding I/Q demodulators  264 - 268 . The I/Q demodulators  264 - 268 , based on a local oscillation, which is produced by local oscillator  100 , down-converts the RF signals into baseband in-phase and quadrature analog signals. 
     The corresponding analog filters  270 - 280  filter the in-phase and quadrature analog components, respectively. The analog-to-digital converters  282 - 286  convert the in-phase and quadrature analog signals into a digital signal. The digital filtering and down-sampling modules  288 - 290  filter the digital signals and adjust the sampling rate to correspond to the rate of the baseband processing, which will be described in  FIG. 11B . 
       FIG. 11B  illustrates the baseband processing of a receiver. The baseband processing includes a space/time decoder  294 , a plurality of fast Fourier transform (FFT)/cyclic prefix removal modules  296 - 300 , a plurality of symbol demapping modules  302 - 306 , a multiplexer  308 , a deinterleaver  310 , a channel decoder  312 , and a descramble module  314 . The baseband processing module may further include a mode managing module  175 , which produces rate selections  171  and settings  179  based on mode selections  173 . The space/time decoding module  294 , which performs the inverse function of space/time encoder  192 , receives P-inputs from the receiver paths and produce M-output paths. The M-output paths are processed via the FFT/cyclic prefix removal modules  296 - 300  which perform the inverse function of the IFFT/cyclic prefix addition modules  186 - 190  to produce frequency domain symbols. 
     The symbol demapping modules  302 - 306  convert the frequency domain symbols into data utilizing an inverse process of the symbol mappers  180 - 184 . The multiplexer  308  combines the demapped symbol streams into a single path. 
     The deinterleaver  310  deinterleaves the single path utilizing an inverse function of the function performed by interleaver  176 . The deinterleaved data is then provided to the channel decoder  312  which performs the inverse function of channel encoder  174 . The descrambler  314  receives the decoded data and performs the inverse function of scrambler  172  to produce the inbound data  98 . 
       FIG. 12  is a diagram illustrating an embodiment of an access point (AP) and multiple wireless local area network (WLAN) devices operating according to one or more various aspects and/or embodiments of the invention. The AP point  1200  may compatible with any number of communication protocols and/or standards, e.g., IEEE 802.11(a), IEEE 802.11(b), IEEE 802.11(g), IEEE 802.11(n), as well as in accordance with various aspects of invention. According to certain aspects of the present invention, the AP supports backwards compatibility with prior versions of the IEEE 802.11x standards as well. According to other aspects of the present invention, the AP  1200  supports communications with the WLAN devices  1202 ,  1204 , and  1206  with channel bandwidths, MIMO dimensions, and at data throughput rates unsupported by the prior IEEE 802.11x operating standards. For example, the access point  1200  and WLAN devices  1202 ,  1204 , and  1206  may support channel bandwidths from those of prior version devices and from 40 MHz to 1.28 GHz and above. The access point  1200  and WLAN devices  1202 ,  1204 , and  1206  support MIMO dimensions to 4×4 and greater. With these characteristics, the access point  1200  and WLAN devices  1202 ,  1204 , and  1206  may support data throughput rates to 1 GHz and above. 
     The AP  1200  supports simultaneous communications with more than one of the WLAN devices  1202 ,  1204 , and  1206 . Simultaneous communications may be serviced via OFDM tone allocations (e.g., certain number of OFDM tones in a given cluster), MIMO dimension multiplexing, or via other techniques. With some simultaneous communications, the AP  1200  may allocate one or more of the multiple antennae thereof respectively to support communication with each WLAN device  1202 ,  1204 , and  1206 , for example. 
     Further, the AP  1200  and WLAN devices  1202 ,  1204 , and  1206  are backwards compatible with the IEEE 802.11 (a), (b), (g), and (n) operating standards. In supporting such backwards compatibility, these devices support signal formats and structures that are consistent with these prior operating standards. 
     Generally, communications as described herein may be targeted for reception by a single receiver or for multiple individual receivers (e.g. via multi-user multiple input multiple output (MU-MIMO), and/or OFDMA transmissions, which are different than single transmissions with a multi-receiver address). For example, a single OFDMA transmission uses different tones or sets of tones (e.g., clusters or channels) to send distinct sets of information, each set of set of information transmitted to one or more receivers simultaneously in the time domain. Again, an OFDMA transmission sent to one user is equivalent to an OFDM transmission (e.g., OFDM may be viewed as being a subset of OFDMA). A single MU-MIMO transmission may include spatially-diverse signals over a common set of tones, each containing distinct information and each transmitted to one or more distinct receivers. Some single transmissions may be a combination of OFDMA and MU-MIMO. Multi-user (MU), as described herein, may be viewed as being multiple users sharing at least one cluster (e.g., at least one channel within at least one band) at a same time. 
     MIMO transceivers illustrated may include SISO, SIMO, and MISO transceivers. The clusters employed for such communications (e.g., OFDMA communications) may be continuous (e.g., adjacent to one another) or discontinuous (e.g., separated by a guard interval of band gap). Transmissions on different OFDMA clusters may be simultaneous or non-simultaneous. Such wireless communication devices as described herein may be capable of supporting communications via a single cluster or any combination thereof. Legacy users and new version users (e.g., TGac MU-MIMO, OFDMA, MU-MIMO/OFDMA, etc.) may share bandwidth at a given time or they can be scheduled at different times for certain embodiments. Such a MU-MIMO/OFDMA transmitter (e.g., an AP or a STA) may transmit packets to more than one receiving wireless communication device (e.g., STA) on the same cluster (e.g., at least one channel within at least one band) in a single aggregated packet (such as being time multiplexed). In such an instance, channel training may be required for all communication links to the respective receiving wireless communication devices (e.g., STAs). 
       FIG. 13  is a diagram illustrating an embodiment of a wireless communication device, and clusters, as may be employed for supporting communications with at least one additional wireless communication device. Generally speaking, a cluster may be viewed as a depiction of the mapping of tones, such as for an OFDM symbol, within or among one or more channels (e.g., sub-divided portions of the spectrum) that may be situated in one or more bands (e.g., portions of the spectrum separated by relatively larger amounts). As an example, various channels of 20 MHz may be situated within or centered around a 5 GHz band. The channels within any such band may be continuous (e.g., adjacent to one another) or discontinuous (e.g., separated by some guard interval or band gap). Oftentimes, one or more channels may be situated within a given band, and different bands need not necessarily have a same number of channels therein. Again, a cluster may generally be understood as any combination one or more channels among one or more bands. 
     The wireless communication device of this diagram may be of any of the various types and/or equivalents described herein (e.g., AP, WLAN device, or other wireless communication device including, though not limited to, any of those depicted in  FIG. 1 , etc.). The wireless communication device includes multiple antennae from which one or more signals may be transmitted to one or more receiving wireless communication devices and/or received from one or more other wireless communication devices. 
     Such clusters may be used for transmissions of signals via various one or more selected antennae. For example, different clusters are shown as being used to transmit signals respectively using different one or more antennae. 
     Also, it is noted that, with respect to certain embodiments, general nomenclature may be employed wherein a transmitting wireless communication device (e.g., such as being an Access point (AP), or a wireless station (STA) operating as an ‘AP’ with respect to other STAs) initiates communications, and/or operates as a network controller type of wireless communication device, with respect to a number of other, receiving wireless communication devices (e.g., such as being STAs), and the receiving wireless communication devices (e.g., such as being STAs) responding to and cooperating with the transmitting wireless communication device in supporting such communications. Of course, while this general nomenclature of transmitting wireless communication device(s) and receiving wireless communication device(s) may be employed to differentiate the operations as performed by such different wireless communication devices within a communication system, all such wireless communication devices within such a communication system may of course support bi-directional communications to and from other wireless communication devices within the communication system. In other words, the various types of transmitting wireless communication device(s) and receiving wireless communication device(s) may all support bi-directional communications to and from other wireless communication devices within the communication system. Generally speaking, such capability, functionality, operations, etc. as described herein may be applied to any wireless communication device. 
     Various aspects and principles, and their equivalents, of the invention as presented herein may be adapted for use in various standards, protocols, and/or recommended practices (including those currently under development) such as those in accordance with IEEE 802.11x (e.g., where x is a, b, g, n, ac, ah, ad, af, etc.). 
     In certain instances, various wireless communication devices may be implemented to support communications associated with monitoring and/or sensing of any of a variety of different conditions, parameters, etc. and provide such information to another wireless communication device. For example, in some instances, a wireless communication device may be implemented as a smart meter station (SMSTA), having certain characteristics similar to a wireless station (STA) such as in the context of a wireless local area network (WLAN), yet is operative to perform such communications associated with one or more measurements in accordance with monitoring and/or sensing. In certain applications, such devices may operate only very rarely. For example, when compared to the periods of time in which such a device is in power savings mode (e.g., a sleep mode, a reduced functionality operational mode a lowered power operational mode, etc.), the operational periods of time may be miniscule in comparison (e.g., only a few percentage or tenths, hundredths [or even smaller portion(s)] of percentage of the periods of time in which the device is in such a power savings mode, or even less). 
     For example, such a device may awaken from such a power savings mode only to perform certain operations. For example, such a device may awaken from such a power savings mode to perform sensing and/or measurement of one or more parameters, conditions, constraints, etc. During such an operational period (e.g., in which the device is not in a power savings mode), the device may also perform transmission of such information to another wireless communication device (e.g., an access point (AP), another SMSTA, a wireless station (STA), or such an SMSTA or STA operating as an AP, etc.). It is noted that such a device may enter into an operational mode for performing sensing and/or monitoring at a frequency that is different than (e.g., greater than) the frequency at which the device enters into an operational mode for performing transmissions. For example, such a device may awaken a certain number of times to make successive respective sensing and/or monitoring operations, and such data as is acquired during those operations may be stored (e.g., in a memory storage component within the device), and during a subsequent operational mode dedicated for transmission of the data, multiple data portions corresponding to multiple respective sensing and/or monitoring operations may be transmitted during that operational mode dedicated for transmission of the data. 
     Also, it is noted that, in certain embodiments, such a device may include both monitor and/or sensor capability as well as wireless communication capability. In other embodiments, such a device may be connected and/or coupled to a monitor and/or sensor and serve to effectuate wireless communications related to the monitoring and/or sensing operations of the monitor and/or sensor. 
     The application contexts of such devices may be varied, and some exemplary though non-exhaustive embodiments are provided and described below for illustrations to the reader. It is also noted that, in some applications, some of the devices may be battery operated in which energy conservation and efficiency may be of high importance. In addition, there are a number of applications in which such devices may be used in addition to or alternatively to smart meter applications; for example, certain wireless communication devices may be implemented to support cellular offload and/or other applications that are not normally or traditionally associated with WLAN applications. Some applications are particularly targeted and directed towards use in accordance with and in compliance with the currently developing IEEE 802.11ah standard. 
     Various mechanisms by which access to the communication media may be achieved may be different and particularly tailored for different contexts. For example, different communication access schemes may be applied at different respective times. That is to say, during a first time or during a first time period, a first communication medium access approach may be employed. During a second time or during a second time period, a second communication medium access approach may be employed. It is noted that the particular communication medium access approach employed any given time may be adaptively determined based upon one or more prior communication medium access approaches employed during one or more time periods. 
     Also, in an application in which there are multiple wireless communication devices implemented therein, different respective time periods may be employed for different groups of those wireless communication devices. For example, considering an embodiment in which multiple STAs are operative within a given communication device, those respective STAs may be subdivided into different respective groups that may have access to the communication medium a different respective time periods. It is noted that anyone given STA may be categorized within more than one group, in that, different respective groups of STAs may have some overlap in their respective contents. By using different respective time periods for use by different respective groups of devices, an increase in media access control (MAC) efficiency may be achieved among anyone or more of the respective devices within the wireless communication system. Also, by ensuring appropriate operation of the overall system, power consumption may be decreased. As mentioned above, this can be of utmost importance in certain applications such as those in which one or more of the devices are battery operated and energy conservation is of high importance. Also, utilizing different respective time periods for use by different groups of STAs can allow for simplification in accordance with MAC or physical layer (PHY) processing. For example, certain embodiments may employ limited preamble processing (e.g., such as in accordance with processing only a subset of, for example, a set of preambles used for normal range and/or extended range type communications) for simplification. In addition, the MAC protocol employed for certain respective time periods can be simplified. 
     It is noted that the in accordance with various aspects, and their equivalents, of the invention described herein may be generally applied to wireless communication devices including any number of types of wireless communication devices (e.g., STAs, APs, SMSTAs, and/or any combination thereof, etc.), certain desired embodiments are particularly tailored towards use with one or more SMSTAs. 
       FIG. 14  illustrates an embodiment  1400  of a number of wireless communication devices implemented in various locations in an environment including a building or structure. In this diagram, multiple respective wireless communication devices are implemented to forward information related to monitoring and/or sensing to one particular wireless communication device that may be operating as a manager, coordinator, etc. such as may be implemented by an access point (AP) or a wireless station (STA) operating as an AP, or to a device which is reachable after forwarding to the AP (e.g., such as a middling communication device). Generally speaking, such wireless communication devices may be implemented to perform any of a number of data forwarding, monitoring and/or sensing operations. For example, in the context of a building or structure, there may be a number of services that are provided to that building or structure, including natural gas service, heating venting and air conditioning (HVAC), electrical service, security service, personnel monitoring service, asset monitoring service, television service, Internet service, and/or any other such service(s), etc. Alternatively, different respective monitors and/or sensors may be implemented throughout the environment to perform monitoring and/or sensing related to parameters not specifically related to services. As some examples, motion detection, temperature measurement (and/or other atmospheric and/or environmental measurements), etc. may be performed by different respective monitors and/or sensors implemented in various locations and for various purposes. 
     Different respective monitors and/or sensors may be implemented to provide information related to such monitoring and/or sensing functions wirelessly to the manager/coordinator wireless communication device. Such information may be provided continuously, periodically, sporadically, intermittently, etc. as may be desired in certain applications. 
     In addition, it is noted that such communications between such a manager/coordinator wireless communication device of the different respective monitors and/or sensors may be cooperative in accordance with such bidirectional indications, in that, the manager/coordinator wireless communication device may direct the respective monitors and/or sensors to perform certain related functions at subsequent times. 
       FIG. 15  illustrates an embodiment  1500  of a number of wireless communication devices implemented in various locations in a vehicular environment. This diagram pictorially depicts a number of different sensors implemented throughout a vehicle which may perform any of a number of monitoring and/or sensing functions. For example, operational characteristics associated with different mechanical components (e.g., temperature, operating condition, etc. of any of a number of components within the vehicle, such as the engine, compressors, pumps, batteries, etc.) may all be monitored and information related to that monitoring may be provided to a coordinator/manager wireless communication device. 
       FIG. 16  illustrates an embodiment  1600  of a number of wireless communication devices implemented in various locations throughout a broadly distributed industrial environment. This diagram pictorially illustrates a number of different respective sensors that may be implemented in various locations that are very remote with respect to one another. This diagram relates to a number of sensors which may be implemented within different locations that have little or no wireless communication infrastructure associated therewith. For example, in the oil industry, different respective pumps may be implemented in very remote locations, and service personnel need physically to visit the different respective locations to ascertain the operation of the various equipment and components there. A manager/coordinator wireless communication device may be implemented within a vehicle, or within a portable component such as laptop computer included within the vehicle, and as the vehicle travels to each respective location in which there are such sensing and/or monitoring devices. As the manager/coordinator wireless communication device enters within sufficient proximity such that wireless communication may be supported with the different respective sensing and/or monitoring devices, information related to such monitoring and/or sensing functions may be provided to the manager/ordinate wireless communication device. 
     While various respective and exemplary embodiments have been provided here for illustration to the reader, it is noted that such applications are non-exhaustive and that any of a variety of application contexts may be implemented such that one or more wireless communication devices are implemented throughout an area such that those one or more wireless communication devices may only occasionally provide information to a manager/ordinate wireless communication device. Any such application or communication system may operate in accordance with the in accordance with various aspects, and their equivalents, of the invention. 
       FIG. 17  illustrates an embodiment  1700  of a wireless communication system including a number of wireless communication devices therein. As may be seen with respect to this diagram, one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device) operates by providing a service period (SP) announcement and/or assignment frame to other wireless communication devices within the wireless communication system. The time period in which the different respective wireless communication devices are provided access to the communication medium is divided into different respective and separate SPs. A given wireless communication device may only effectuate communication medium access during an SP in which it is authorized to do so. 
       FIG. 18  illustrates an alternative embodiment  1800  of a wireless communication system including a number of wireless communication devices therein. It is also noted that the different respective wireless communication devices may be subdivided into a number of specific classes or groups that are permitted to transmit only during specific SPs. For example, there may be a first group of wireless communication devices (e.g., SMSTAs) that is permitted to transmit during a first SP, and a second group of wireless communication devices (e.g., STAs that are not specifically SMSTAs) is permitted to transmit during a second SP, etc. 
     A given wireless communication device of a particular class that is not given explicit permission to transmit within a specific SP is not allowed to transmit during that SP. However, it is noted that the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device) may provide certain exceptions for one or more of the respective wireless communication devices. For example, an exception announcement may be transmitted from that one of the wireless communication devices to other of the wireless communication devices. 
     In accordance with such classification and/or grouping of the different respective wireless communication devices, it is noted that certain classes and/or groups may be assigned to more than one specific SP. For example, wireless communication devices of a given class and/or group may be permitted to perform transmission during multiple respective SPs. Also, more than one class and/or group may be assigned to any given SP, such that wireless communication devices associated with a first class/group as well as wireless communication devices associated with a second class/group may all be permitted to perform transmission during a given SP. 
     A special SP may be created for beacon transmission from the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device) to the other wireless communication devices. For example, such a beacon transmission SP may be provided to ensure that there is no permission for any class of other wireless communication devices to operate during a given one or more time periods. Alternatively, the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device) may also allow some classes and/or groups to operate within the time period associated with the beacon transmission related SP. 
     As the reader will understand, given that a number of different respective wireless communication devices are all operative within a wireless communication system and may not all be temporally synchronized to the same clock, there may be some differentiation with respect to the timing and clock accuracy within the different respective wireless communication devices. As such, the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device) will serve as the reference by which SP timing is effectuated among the respective wireless communication devices. That is to say, each of the other respective wireless communication devices will maintain a local clock that is synchronized to the reference clock within or maintained by the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device), such as in accordance with the timing synchronization function (TSF) as specified in accordance with IEEE 802.11 WLAN operation, or in accordance with some other clock having an acceptable (usually high) accuracy. However, it is also noted that certain of the wireless communication devices may be exempt from maintaining synchronization to this main/master clock within or maintained by the one of the wireless communication devices (e.g., an AP, a STA operating as an AP, a manager/coordinator wireless communication device). For example, certain of the wireless communication devices may enter into relatively long periods of sleep, and such operation may prevent the respective ability to maintain synchronization with this main/master clock. 
       FIG. 19  illustrates an embodiment  1900  of time division multiple access (TDMA) operation, as may be effectuated at a media access control (MAC) layer, within various wireless communication devices. This diagram pictorially shows, as a function of time, how different respective wireless communication devices are provided access to the communication medium. Any of a number of different schedules may be employed to provide for access by the various wireless communication devices (e.g., as shown by various respective TDMA options shown at the top and middle/bottom of the diagram as separated by the ellipsis). It is noted that the respective time periods in which the wireless communication devices are provided access to the communication medium need not be uniform in length. Different respective time periods of different respective durations may be provided for different respective wireless communication devices. 
     Referring to the diagram, it may be seen that those wireless communication devices having the characteristic associated with type “a” are provided the opportunity to have access to the communication system during those respective hashed portions (lines extending from lower left to upper right) along the respective time axis, those wireless communication devices having the characteristic associated with type “b” are provided the opportunity to have access to the communication system during those respective hashed portions (lines extending from upper left to lower right) along the respective time axis, and those wireless communication devices having the characteristic associated with type “c” are provided the opportunity to have access to the communication system during those respective hashed portions (lines extending both vertically and horizontally) along the respective time axis. 
     In other words, different respective service periods (SPs) are provided so that wireless communication devices associated with different classes and/or groups may be provided access to the communication medium during those respective times. 
       FIG. 20  illustrates an embodiment  2000  of TDMA operation on multiple, respective frequencies, spectra thereof, channels, and/or clusters, as may be effectuated at a MAC layer, within various wireless communication devices. This diagram has some similarities to the previous embodiment  1900  and  FIG. 19 , with at least one difference being that frequency diversity is also employed in conjunction with temporal diversity. That is to say, TDMA signaling may be effectuated on a number of different respective channels (and/or clusters, etc.). 
     In accordance with such operations and principles as described herein, it is noted that there may be one or more respective dedicated SPs that are used for a given class/group of wireless communication devices. For example, a new STA may associate or disassociate during certain of the SPs. As one example, an AP may specify which of the SPs can be used for a new STA to send an association requests. Such information may be provided from the AP within a beacon or some other type of frame, such as a probe response frame, or a management frame. 
     Also, during some SPs, a different preamble may be used. For example, to reduce implementation complexity, different classes of preambles may be employed such as may be employed in accordance with the currently developing IEEE 802.11ah standard in which a first type of preamble may be employed in accordance with normal range operations while a second type of preamble may be employed in accordance with extended range operations. In such communication system applications in which more than one preamble is employed, having a separate and respective SP for operation using only one of those types of preambles may serve to allow STAs to be implemented and operative in accordance with only one of those types of preambles. For example, provided that an STA is allowed to operate only during one or more specific SPs, then such an STA need not necessarily have capability to accommodate multiple respective preamble types. 
     Also, in an effort to save time, extra preamble processing may be avoided on those relatively low power STAs when possible. For example, one type of preamble may be relatively shorter than another type of preamble, and avoiding operation on a relatively longer type of preamble may save time, energy, etc. Also, in an effort to save overhead, a relatively longer preamble type may be avoided when needed. For example, in the situation that one type of preamble may be relatively shorter than another type of preamble, operation that would require all of the STAs to use a shorter type of preamble during specific SPs could potentially increase efficiency of operation in those respective SPs. For example, in operation in communication systems in which certain of the wireless communication devices may be operative in accordance with IEEE 802.11n and/or IEEE 802.11ac, such as in accordance with mixed mode operation such that some of the wireless communication devices are operative in accordance with one standard, other of the wireless communication devices are operative in accordance with the other standard, and certain of the wireless communication devices may be operative in accordance with both of the standards, such a mixed mode preamble may be relatively longer than a Greenfield preamble, and overhead associated with the preamble may be reduced. 
     Moreover, with respect to certain applications that may require little and/or no latency (e.g., such as those related to voice, video, and/or other real-time interactive communications), the latency associated for such traffic may be implemented to be less than some particular threshold (e.g., less than T milliseconds). Providing specific TDMA SPs may be used to help minimize such latency and reduce jitter within such applications. For example, voice traffic may be provided with its own respective SP because it has the strictest latency requirements in accordance with such a real-time, bidirectional, and interactive communication application. Voice traffic need not be constrained to a single type of SP, however. For example, if the aggregated duration of non-voice over Internet protocol (VoIP) SPs would be more than some predefined threshold, then voice traffic can be assigned to one or more additional SPs. Such operations and considerations may also be performed with respect to video applications as well. 
     For example, an AP may allow for transmissions associated with voice, video, etc. in any given SP as desired or that may be acceptable for such voice, video, etc. applications. During those respective SPs that can be used for voice, video, etc. applications, the voice, video, etc. content therein may be given priority over other traffic in the SP if it is deemed necessary. For example, because of the inherently aggressive latency requirements associated with voice, video, etc. applications, content respectively associated air with may be given priority over other types of content. 
     With respect to synchronization of SPs, it is noted that the timing synchronization function (TSF) as specified in accordance with IEEE 802.11 WLAN operation, or in accordance with some other clock having an acceptable (usually high) accuracy, may be used as a reference to specify the beginning of each respective SP. As the reader will understand, with respect to highly diverse wireless communications systems in which a number of different wireless communication devices are implemented therein, including some of those that may be battery operated, have relatively inaccurate clocks, and/or some other operational limitations, synchronization may be challenging. Moreover, with respect to certain of the wireless communication devices that may enter into relatively long sleep periods, synchronization may also be challenging, in that, upon entering into an awakening from different respective sleep periods, there may be inaccuracy incurred or introduced with the internal timing and clocks therein. 
     As may be understood within such applications, some of the wireless communication devices may go to sleep for a relatively long period of time after having been awake and operational. As such, those respective wireless communication devices may not necessarily receive a beacon for a relatively long period of time. The TSF may not be an adequate, acceptable, or valid reference for certain of the SPs if the TSF has not been synchronized for a relatively long period of time (e.g., Y second(s)). As such, for those wireless communication devices in which timing and/or synchronization may be or potentially may be problematic, such as low power (LP) STAs, the TSF may be integrated and/or included within communications such as data exchanges between an AP and those respective STAs that may wake up relatively less frequently to receive beacons for the purpose of synchronizing their respective internal timers. That is to say, certain information such as TSF may be piggy-backed onto or included within communications to those respective wireless communication devices. Also, some of the LP STAs may contend for communication medium access during other SPs. For example, a given wireless communication device&#39;s respective TSF timer may be off by more than a certain amount (e.g., such as a threshold, such as more than N msec after sleeping for S seconds). In addition, if desired within a particular embodiment, such LP STAs may be allowed to contend for access to the communication medium at all times, instead of within the bounds of any specific SP or SPs, as such LP STAs may not be able readily to discern the respective boundaries of the SPs for any of a number of reasons including a potentially less than fully accurate internal clock, the fact that they are asleep for relatively long periods of time, the fact that they get out of synchronization with respect to the main/master clock to which the other wireless communication devices are synchronized, etc. 
     In addition, with respect to operating in accordance with TDMA signaling, and given the consideration that different respective wireless communication devices will operate using different respective internal clocks (e.g., oftentimes based upon an internal operating crystal), even though there may be certain synchronization operations that will attempt to minimize the lack of synchronization between different respective devices, in a real world application, there may unfortunately be certain differences, inaccuracies, etc. between the different respective clocks of the different respective devices. For example, crystals used for wireless communication devices (e.g., STAs) within the context of a WLAN can have an accuracy specified in a certain amount of parts per million (e.g., X ppm). The accuracy of such a crystal employed within a given wireless communication device results in a variance of the local TSF clock that is used in that particular wireless communication device as a reference for the beginning of each respective SP. Those wireless communication devices that are not specifically designated or operative as being low power (e.g., non-LP STAs) may be able to correct their respective TSF timers by using information received from a manager/coordinator wireless communication device (e.g., an AP, STA operating as an AP, etc.), such as may be received in beacons from such a manager/coordinator wireless communication device. If a given wireless communication device is not able to receive, process, etc. some number of certain respective beacons (e.g., because it has been sleeping, is asleep, is at less than a full functionality state, etc.) that respective wireless communication device may not be able to correct for error with respect to timing references before the error accumulates to a significant and unmanageable size (e.g., the difference in timing and/or error being beyond what can be easily corrected). 
     Considering an illustrative example, if T is the amount of time that a wireless communication device has been asleep, then that particular wireless communication device can have as much as an error of E=T×X×10 −6  in its respective TSF clock when it awakes (e.g., considering T being the amount of time that the wireless communication device is asleep, X being the accuracy specified in ppm, and E being the error). As an even more detailed example, by assigning values to these respective variables, T=7200 seconds (two hours), X=20, then the associated error, E, will be approximately 150 ms. 
     Generally speaking, the respective boundaries associated with an SP are expected to have a tolerance of less than a relatively small amount (e.g., approximately 0.1 ms). In order to allow for correction of the TSF timer in a wireless communication device (e.g., an LP STA) without requiring a particular wireless communication device to wait to receive a beacon, the TSF timer may be embedded in one or more response frames sent from a manager/coordinator wireless communication device (e.g., an AP, STA operating as an AP, etc.) to any of the other wireless communication devices within the wireless communication system (e.g., the STAs within the system, BSS, etc.). In addition, while it is noted that certain timing related information, including TSF timer related information, may be included within beacons that are transmitted from one wireless communication device to other wireless communication devices, it is noted that any desired additional frames (e.g., not specifically beacons) may alternatively or also include such timing related information, including TSF timer related information, and may be sent by anyone of the wireless communication devices (e.g., the manager/coordinator wireless communication device or any of the other wireless communication devices, including any STA) to provide for additional or frequent timing information to allow a given wireless communication device (e.g., an awakening STA) the opportunity to synchronize its respective clock without specifically having to wait for the arrival of a beacon. 
     Also, to avoid the possibility of a wireless communication device transmitting outside of an SP designated for that particular wireless communication device, that wireless communication device may schedule a respective wake-up time closer towards the middle of an SP. As may be understood, because of the potentiality of relatively inaccurate timing in regards to the internal timing reference of a given wireless communication device, by scheduling a wake-up time to be further away from the respective edges of an SP, there would be less of a likelihood that a given wireless communication device would awaken and begin a transmission at an SP edge/boundary. 
     Also, referring again to the variables employed above, where E being an associated error, if it is determined that E&gt;P×Tdur (where Tdur is the duration of a particular SP), and also where P&lt;½, then TDMA signaling may not be the best solution or appropriate for a given wireless communication device (e.g., a STA). For example, if a STA is specifically an LP STA, then that particular STA might not wake up for synchronization to contain the timing error below a particular value, namely, below the value of P×Tdur. Also, those STAs which may not specifically be LP STAs, but may alternatively be referred to as medium power low data rate STAs (MPLD STAs), maybe operative to wake up occasionally to receive beacons and maintain timing accuracy. For example, even if such MPLD STAs do not necessarily stay asleep or inactive for periods of time that are sufficiently long enough to cause a TSF tracking error exceeding some threshold (e.g., 0.1 ms), such wireless communication devices may nonetheless wake up to receive beacons and maintain sufficient or acceptable timing accuracy. Stated another way, if the internal clock of a given wireless communication device cannot maintain accuracy sufficiently well (e.g., such as with at least one half of the accuracy of the manager/coordinator wireless communication device), then TDMA signaling may potentially not be the best or preferred implementation for such an embodiment. Analogously, for those wireless communication devices that stay asleep for such a long period of time that maintaining timing synchronization even within such a relatively generous constraint as described above, an alternative implementation to TDMA signaling may be preferred. 
       FIG. 21  illustrates an embodiment  2100  of multiple service periods (SPs) for use in various wireless communication devices within a wireless communication system. As can be seen with respect to this diagram, a given SP announcement/assignment may be provided to direct operation for a relatively long subsequent period of time, in which different communication medium access options may be employed (e.g., enhanced distributed channel access (EDCA), polled, scheduled, carrier sense multiple access/collision avoidance (CSMA/CA), etc. and/or any combination thereof, etc.) during different respective periods of time. 
     For example, at the top of the diagram, a given announcement/assignment frame is provided (e.g., from a manager/coordinator wireless communication device) to a number of other wireless communication devices that specifies the different respective medium access options that are performed sequentially over a period of time, and the pattern is repeated. That is to say, the SP instances, which may be determined by a manager/coordinator wireless communication device (e.g., an AP), may be periodic in certain instances. The announcement/assignment may include the number of times in which the overall pattern is repeated, the respective order of the different respective medium access options performed, and/or other characteristics associated with such periodicity, etc. 
     As may be seen with respect to the middle of the diagram, there may be a given time period in which there is no communication medium access allowed by any of the respective wireless communication devices. Also, as may be seen with respect to the bottom the diagram, there may be multiple respective time periods in which there is no communication medium access allowed by any of the respective wireless communication devices. 
       FIG. 22  illustrates an alternative embodiment  2200  of multiple SPs for use in various wireless communication devices within a wireless communication system. As can be seen with respect to this diagram, there may be great variability and variation between different respective SP announcements. For example, a first SP announcement may indicate a first one or more communication medium access options to be performed thereafter. A second SP announcement may indicate a second one or more communication medium access options to be performed thereafter. Different respective SP announcements may also include one or more common communication medium access options. As also described respect other embodiments and/or diagrams herein, a given SP announcement may be adaptively generated based upon prior history, operations, and/or environmental conditions, etc. such as with respect to one or more other prior SPs. That is to say, such SP announcement may be adaptively determined based upon any one or more prior considerations. 
     Generally speaking, each respective SP may be described within an SP announcement and/or assignment that is provided from one of the wireless communication devices within the wireless communication system (e.g., a manager/coordinator wireless communication device, AP, STA operating as an AP, etc.). As may be seen with respect to this diagram, such an SP announcement may be periodic. Also, such an SP announcement may be done through any of a variety of different types of frames transmitted from a wireless communication device (e.g., beacons, regularly transmitted frames including data frames, management frames, acknowledgment frames, probe responses, etc.). Also, it is noted that while certain embodiments operate by providing respective SP announcements somewhat regularly (e.g., periodically, in accordance with a uniform time base, etc.), alternative embodiments envision providing such SP announcements at other respective times then periodically (e.g., providing such SP announcements at non-specified/non-uniform/non-periodic times, such as may be made in accordance with certain events, conditions, actions, etc.). 
     Among the various amount of information that may be included within various embodiments of an SP announcement frame, a given embodiment of an SP announcement frame may include those particular wireless communication devices which are allowed and disallowed users of one or more SPs that are described or correspond to a given SP announcement frame. For example, in certain embodiments, an association ID (AID) (e.g., a shortened, but unique substitute for a full 48 bit MAC address allowed and/or disallowed from operating in the SP). For example, an AID may be viewed as being a one-to-one mapping of the full 48 bit MAC address to a relatively shorter bit address, such as 11 bits, that is unique within the BSS). That is to say, within a given BSS, a manager/coordinator wireless communication device (e.g., AP) can assign the respective AIDs to the respective wireless communication devices therein. 
     With respect to categorization of those wireless communication devices which may be allowed and/or disallowed from operating within a respective SP, the definition of an entire class may be made and such information may be provided within an SP announcement frame. For example, different types of wireless communication devices may be categorized within one or more classes based on their respective needs and/or characteristics. For example, based on any of a number of considerations including the frequency of transmission of a given wireless communication device, the bandwidth requirements needed (e.g., sensor and/or monitoring devices/STAs may require relatively lower bandwidth than other devices/STAs), the traffic patterns associated therewith, the frame format capabilities, quality of service (QoS)/latency limits for different respective streams (e.g., including their relative QoS/latency limits such as for different types including voice, video, data, etc.), existence of dedicated traffic streams to be delivered by or to a particular wireless communication device, etc., the different respective wireless communication devices may be categorized into one or more allowed classes and disallowed classes. 
     Also, it is noted that, within a given BSS, there may be different respective wireless communication devices having mixed capabilities (e.g., IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ah [currently under development], and/or any other combination of such IEEE 802.11x functionality sets, etc.). In certain situations, there may be different respective preamble types employed, such as a first preamble type corresponding to normal or typical operations (e.g., relatively high throughput as may be associated with a handset, laptop, etc.) and a second preamble type corresponding to another application type (e.g., below noise acquisition, having a relatively longer preamble, such as may be employed for sensing and/or monitoring applications). Operation in accordance with a given SP may specify that those respective wireless communication devices operating within that SP must operate within a particular operational mode (e.g., in accordance with an extended range mode of operation or in accordance with normal mode of operation). 
     Also, with respect to the categorization and classification of the respective wireless communication devices as operating within a given SP, one or more of the classes may be determined by any one of the wireless communication devices (e.g., not necessarily only by a manager/coordinator wireless communication device, such as an AP). If desired, such categorization and classification of the respective wireless communication devices may be performed in a cooperative manner, such that one or more of the wireless communication devices within the wireless communication system provides certain classification, and that classification is negotiated and ultimately approved by a manager/coordinator wireless communication device, such as an AP. In even other embodiments, such classification may be performed during association by a manager/coordinator wireless communication device, such as an AP. These respective class assignments may be made in the manner that allows for the spacing of potential transmitters sufficiently far apart from one another in time (e.g., respective transmission from the various communication devices being sufficiently temporally separated) as to reduce a probability of collisions from the respective wireless communication devices. Also, the categorization of the respective wireless communication devices into one or more different respective groups may be achieved in accordance with group ID related operations, as described in one of the U.S. utility patent applications incorporated by reference above. For example, a group of wireless communication devices may be specified and identified in a separate exchange, and those wireless communication devices may be assigned to a specific group ID value. The use of such a group ID may be one possible means by which certain wireless communication devices may be specified and identified and allowed to operate during a particular SP. 
     Moreover, with respect to other characteristics associated with an SP announcement, the start of the SP may be associated with the clock of the transmitting wireless communication device from which the SP announcement was sent (e.g., a manager/coordinator wireless communication device, such as an AP) as a reference. As described with respect to certain embodiments and/or diagrams herein, such an SP announcement may indicate a periodicity of one or more subsequent SPs (if applicable), the duration of the one or more subsequent SPs, the respective allowed communication medium access options employed or allowed during the one or more subsequent SPs (or his subdivisions thereof) (e.g., enhanced distributed channel access (EDCA), polled, scheduled, carrier sense multiple access/collision avoidance (CSMA/CA), etc. and/or any combination thereof, etc.), whether or not any frame format types are allowed or disallowed, and/or any other desired information, etc. Also, an SP identifier may be included with any embodiment of an SP announcement that uniquely identifies an SP, a periodic set of SPs, an aperiodic set of SPs, etc. Generally, such an SP identifier, or SP identifiers, may be implemented in such a way that each respective SP identifier may be viewed as an index that corresponds to a number of parameters which may be defined elsewhere (e.g., within a lookup table, memory, chart, etc.). 
     Also, an SP announcement may be used as a mechanism to quiet the communication network during one or more given SPs for all other type of traffic therein. For example, an SP announcement may be used to provide information to those wireless communication devices not specified within a given SP regarding when those non-specified wireless communication devices are specifically not to transmit. That is to say, an SP announcement may include a description of the SP start, the periodicity thereof if any, the duration, one or more allowed classes, one or more disallowed classes, etc. and such information may be used by certain non-participating classes to determine when specifically they are not to transmit. Generally, if a wireless communication device not explicitly provided information regarding it being specifically allowed or disallowed, this additional information within an SP announcement may be used to deduce whether or not that wireless communication device can or cannot transmit during one or more SPs specified within an SP announcement. 
     Also, any number of frame exchanges may be used to quiet the communication network for other types of traffic during a given SP. As an example, a manager/coordinator wireless communication device, such as an AP, can send specific keep out messages to non-participating classes at the beginning of each respective SP. Such a manager/coordinator wireless communication device, such as an AP, may also announce an SP at the start of the SP within announcement transmission which immediately precedes the start of the SP. Such an announcement may include clock information that allows those wireless communication devices with relatively lower accuracy clocks (e.g., LP STAs) to synchronize their respective clocks. This announcement may also contain additional information such as an indication of which SP is starting and may also repeat any previously announced information about the SP as well (e.g. duration, one or more allowed classes, one or more disallowed classes, etc.). 
     As may be understood, such an announcement may operate to aid in the synchronization of clocks of the respective wireless communication devices, taking into account the inaccuracy of some of the clocks used by those wireless communication devices. That is to say, a wireless communication device employing a relatively lower accuracy clock may awaken earlier than necessary in order to ensure that the wireless communication devices awake at the start of the SP. That is to say, as described with respect to other embodiments and/or diagrams herein, if a given wireless communication device which is not particularly certain of the time (e.g., because of the relatively lower accuracy or potentially inaccurate clock), then that wireless communication device will not be certain of exactly when a given STB begins. By providing an AP announcement at the start of the SP, synchronization may be achieved for those wireless communication devices that are waiting and may also provide a definitive indication of the start of the SP. Also, if the SP is not expected to contain any wireless communication devices that do have or potentially have relatively lower accuracy or potentially inaccurate clocks (e.g., the SP may not include any LP STAs), then the manager/coordinator wireless communication device, such as an AP, may refrain from announcing the start of the SP in an effort to reduce overhead. That is to say, if there are not expected to be any wireless communication devices within the group that may have problems with respect to timing and synchronization, then a specific announcement at the start of an SP may not be necessary or desirable in such specific situations. 
     Also, such a manager/coordinator wireless communication device, such as an AP, may use a shortened form of such an announcement (e.g., employing such an announcement that contains only an SP identifier and a subset of the information that was contained in a previous SP announcement); again, such variations and operations may be employed in an effort to reduce overhead. By using or referencing information that was included in one or more prior SP announcements, overhead and information within a current SP announcement may be reduced. 
     With respect to the specific communication medium access options performed during each respective SP, or during each respective subdivision of an SP, any of a variety of different types of communication medium access may be employed, including enhanced distributed channel access (EDCA), polled, scheduled, carrier sense multiple access/collision avoidance (CSMA/CA), etc. and/or any combination thereof, etc. 
     For some particular classes of traffic, polling may be used during their respective SPs. For example, with respect to those wireless communication devices that may only occasionally or periodically operate as transmitters (e.g., those wireless communication devices performing monitoring and/or sensing operations, such as SMSTAs, etc.), a manager/coordinator wireless communication device, such as an AP, will know particularly when, or approximately when, those wireless communication devices should have new information to send (e.g., because of any periodicity in their respective operation), and the manager/coordinator wireless communication device, such as an AP, may then poll those respective wireless communication devices at or approximately at those times. It is also noted that all of the respective wireless communication devices need not necessarily be polled during a single SP, in that, some of the wireless communication devices may be polled only every N-th SP in a sequence of M periodically repeating SPs (e.g., every third SP, or every 10th SP, etc.). 
     Also, if a particular wireless communication device, such as a monitoring and/or sensing wireless communication device, does not respond to a poll within a certain period of time, then the manager/coordinator wireless communication device, such as an AP, can do any one of a number of different things. For example, the manager/coordinator wireless communication device may wait for a period of time and then try to poll that same non-responding wireless communication device again. Alternatively, the manager/coordinator wireless communication device may move on to and begin polling the next wireless communication device (e.g., the next monitoring and/or sensing wireless communication device) in the list. In addition, as also described with respect to other embodiments and/or diagrams herein, various respective communications may be employed to provide system clock information. In the context of performing such polling, to allow an awakening wireless communication device to determine if it has in fact awakened at the right time, a respective polling frame can include system clock information. In other words, a polling frame can be used as another means to synchronize the respective clocks of the respective wireless communication devices within the communication system. A polling frame, as well as any other frame communicated between wireless communication devices, may be used for clock synchronization purposes. 
     In an effort to minimize potentially wasted bandwidth during one or more SPs, different operations may be employed to reclaim unused SP time. In addition, some of the SPs may be terminated before their scheduled end by a manager/coordinator wireless communication device, such as an AP. Considering an exemplary situation, when allowed class of wireless communication devices has little or no traffic for a given SP, then that SP may be terminated before its scheduled end. Alternatively, other mechanisms may be used to end an SP before its scheduled time. 
     For example, with respect to an AP governed implementation, such as in which an AP is polling different respective STAs within the wireless communication system, a poll-based SP may be terminated by the AP when it determines or sees that it has decided not to poll any additional STAs. For example, considering that an SP is for a specific class and that an AP has already polled all members of the class, then the AP may terminate the SP early given that all of the respective members of the class have already been polled. Alternatively, such an AP may terminate the SP implicitly by polling a STA that is not specifically included within the class of that particular SP (e.g., a poll may be provided to a specific individual STA or to a group of STA&#39;s or to a class of STA&#39;s that were not members of the one or more classes specifically allowed for that given AP). Alternatively, an SP may be ended early by an AP that transmits a packet indicating that other STA&#39;s may use the remainder of the SP. That is to say, other classes, other groups, other individual STA&#39;s, etc. may be permitted to use the remainder of the SP after receiving the packet that indicates that they may do so. 
     Considering another embodiment, with respect to a scheduled SP implementation, such as in which an AP has previously arranged schedules for STA&#39;s to exchange traffic within a given SP, then a STA may indicate during its respective SP that it does not have any traffic associated with a specific STA or for all STA&#39;s for the current SP and/or one or more subsequently scheduled SP&#39;s. In response, such a manager/coordinator wireless communication devices, such as an AP, may receive an indication from an STA to end an SP earlier than scheduled in order to reclaim the unused portion of the SP for use by other STA&#39;s, as described above. 
     In accordance with such operations as may be employed to identify and reclaim unused time within SP, certain considerations may be performed particularly when operating in accordance with an SP that uses an EDCA mechanism. For example, an EDCA based SP-termination mechanism may be implemented to start with and “intent to compete” signal (e.g., such as in accordance with intending to compete for access to the communication medium) within a specified window that occurs at the beginning of the SP. Such an intent to compete signal may be transmitted by any wireless communication device (e.g., STA) that is eligible and willing to compete for communication access during the SP. The intent to compete maybe implemented such that it is recognizably different from other transmitted signals and very short in time duration (e.g. one or two OFDM symbols). If a manager/coordinator wireless communication device, such as an AP, detects any intent to compete signal, then the manager/coordinator wireless communication device may be implemented to repeat the intent to compete after the end of the specified window to indicate to all members of the BSS that the SP will be used. For example, there may be certain wireless communication devices within the system that are unable to hear the intent to compete signal that is provided from another one of the wireless communication devices, but the manager/coordinator wireless communication device will most likely be able to hear the intent to compete signal, and that intent to meet signal may be forwarded on to the other wireless communication devices. The absence of an intent to compete signal during the window or in the time allotted for the manager/coordinator wireless communication devices (e.g., AP) to repeat the indication immediately after the window allows other class wireless communication devices (e.g., STAs) to determine if the SP will be used. 
     In an alternative embodiment, such a manager/coordinator wireless communication device, such as an AP, may be implemented to direct the reuse of certain remaining portions of an SP. For example, if an AP detects an idle period, and if the duration of such an idle period exceeds some threshold, then the AP may ask the other wireless communication devices (e.g., STAs) if they desire to use that remaining idle period of SP. For example, within an SP, the AP may be implemented to look for and detect and an IDLE period having the characteristics such that the IDLE period&gt;(CWMAX+1)*SLOTTIME+AIFS (CWMAX for the class(es) given permission to operate within the SP). 
     If the required minimum IDLE is detected, then the AP may be implemented to send a “Permission to use” message to the other wireless communication devices within the system. Such permission to use the remaining portion of an SP may be individually sent to respective wireless communication devices, sent in accordance with BCAST, and/or sent specifically to any class or group or subclass, etc. If desired, the AP itself may be implemented to choose to use any unused time within SP specifically for itself (e.g., to the exclusion of other wireless communication devices within the system). It is noted that CWMAX can be different for each different class (e.g., a first class having a first CWMAX, a second class having a second CWMAX, etc., and those respective values may be adaptively adjusted and/or determined). 
     In addition, an AP can choose to share the SP earlier rather than after (CWMAX+1)*SLOTTIME+AIFS of IDLE time. For example, if there is an overlapping BSS that has scheduled the time of this SP for some other purpose that overlaps with this SP, then the medium might not become IDLE for (CWMAX+1)*SLOTTIME. The service period may not be terminated earlier than some predetermined time (e.g., X microseconds/μsec) The value X μsec may be calculated based on the accuracy of the crystal and the maximum time that a user of each class can go to sleep and not receive the beacon or other packets for synchronization. In addition, the value of X μsec may be tailored specifically for those wireless communication devices that may have relatively lower accuracy or inaccurate clocks. For example, in certain embodiments, the largest value that may be used for value X μsec may be specifically tailored to be approximately ½ of that duration of an SP (e.g., particularly for those wireless communication devices having relatively lower accuracy or inaccurate clocks). In addition, different respective values of X may be employed for different respective classes or groups of wireless communication devices (e.g., a first class or device having a first X, a second class or device having a second X, etc., and those respective values may be adaptively adjusted and/or determined). 
       FIG. 23  illustrates an embodiment  2300  of TDMA termination for various wireless communication devices within a wireless communication system. With respect to this exemplary TDMA termination embodiment, a manager/coordinator wireless communication device, such as in AP, maybe implemented to detect IDLE duration&gt;(CWMAX+1)*SLOTTIME+AIFS during an SP that is for STA of class L. In response to this, the manager/coordinator wireless communication device may be implemented to send permission to the other wireless communication devices within the system to use remainder of SP to STAs of class M. Alternatively, the manager/coordinator wireless communication device may be implemented to send permission to all classes or to an individual STA, etc. The class M wireless communication devices (e.g., STAs) begin to use leftover class L SP time. 
     Also, within certain embodiments, operations may be effectuated using a subset of PHY preambles in some SPs. For example, there may be different preambles used for different use-cases in accordance with various applications, including those operating in compliance with the currently developing IEEE 802.11ah standard. For example, different respective preamble types may be employed including long-range preamble as compared to normal range preamble. Alternatively, other variations of different respective preamble types may include those related towards multi-user (MU) applications and those related towards single-user (SU) applications. Generally speaking, there may be some situations in which there is variability among the respective preamble types employed as specifically tailored to different respective wireless communication devices. The use of a specific SP or SPs may be used to restrict the type of PHY preambles that are used to transmit packets in the SP in order to effectuate any of a number of considerations. 
     For example, with respect to reducing overhead, the specification or restriction of a specific SP or SPs may be employed by avoiding the necessity of having a combined header that is receivable by those wireless communication devices (e.g., STAs) with different receiver capabilities (with respect to receiving preambles). 
     With respect to reducing the complexity of those wireless communication devices (e.g., STAs), those respective wireless communication devices may be implemented to be relatively simpler because they do not have to implement capability to receive all possible and variant preamble types. 
     With respect to reducing power consumption of those wireless communication devices (e.g., STAs), those respective wireless communication devices that are implemented and do have the capability of multiple preamble processing can disable processing for those particular preambles not allowed in an SP in order to save power. For example, such a given wireless communication devices may be limited to operate in accordance with a reduced or less than full functionality set. 
       FIG. 24  illustrates an embodiment  2400  of a smart meter station (SMSTA) entering a sleep period for a period of time and awakening for a subsequent data transmission. As has been described also with respect other embodiments, any of a number of different wireless communication devices may be implemented as a smart meter STA (SMSTA), generally described as a STA that goes to sleep L seconds and after it wakes up, wishes to transmit a small amount of data. Overall, the data rate, D, that may be achieved by such a device may be D&lt;1 kilobits per second (kbps) as measured over the combination of sleep and transmission time. In various embodiments, the duration of this sleep period, L, may be viewed as being measured in minutes or hours or days. Generally speaking, the period of time in which the STA is awake is relatively much shorter in duration than the period of time in which the STA is asleep (e.g., such as by one or multiple orders of magnitude). For example, the STA may be awake for a relatively short period of time (e.g., less than 1 second or a few seconds in some situations), and STA may be asleep for a relatively long period of time (e.g., multiple minutes, hours, or days, etc.). 
     Also, such wireless communication devices are often times implemented as being relatively low power (LP) wireless communication devices, such as implemented as being LP STAs as described elsewhere herein. For example, such devices may be implemented as battery-operated systems in which it would be desirable to have battery replacement very seldom (e.g., battery replacement time measured in years). 
     With respect to the media access control (MAC) related function of such an SMSTA, the respective transmission times of the multiple SMSTA&#39;s may be distributed such that the probability of collision among one or more SMSTA&#39;s and other STA&#39;s using a given portion of frequency spectrum is minimized. For example, a manager/coordinator wireless communication devices, such as an AP, maybe implemented to form groups of SMSTAs and assigns different respective wake up times to each respective group of SMSTA&#39;s. The manager/coordinator wireless communication devices may be implemented to transmit relatively short frames that may contain any one or more of the following: timing information for SMSTA clock synchronization to the AP clock, schedule information for future transmissions by SMSTAs, and/or poll request for a transmission from an SMSTA or set of SMSTAs. 
     Since the SMSTAs may go to sleep for relatively long periods of time (e.g., days, months, etc.), the TSF timer on any such SMSTA may unfortunately drift from the TSF timer on the AP. The MAC scheme should be functional in spite of an inaccurate TSF timer at the SMSTA. As may be understood, certain wireless communication systems containing one or more SMSTAs may be battery-operated. In such applications, power efficiency may be an important factor in the design of the MAC scheme. 
     Moreover, there may be certain wireless communication devices that made appear as being hidden wireless communication devices. For example, hidden STAs are an issue in many SMSTA scenarios (including those operating in accordance with the currently developing IEEE 802.11ah standard) as the AP may be located at a higher location than the STAs in the BSS. For example, an AP may be located on top of a building, allowing line of sight (LOS) path for AP-client, but client-client paths are commonly obscured (e.g., to communication pathways between respective STAs or obscured). As a result, the MAC scheme should be robust in the presence of hidden STAs. It is also noted that while many of the embodiments described herein are directed towards SMS T a related applications, they may be generally applied to any wireless communication system including those that include only state STA&#39;s, as well as to any wireless communication system including both STA&#39;s as well as SMSTA&#39;s. 
       FIG. 25  illustrates an embodiment  2500  of a multiple respective wakeup windows, being distributed over time, corresponding to a number of respective SMSTAs. As may be seen with respect to this diagram, different respective SMSTA&#39;s may operate such that they wake up the different times. By distributing the respective wake up times of the devices, such as may be performed by a manager/coordinator wireless communication device, such as an AP, the probability of collisions among the respective SMSTA&#39;s or other STA&#39;s within the wireless communication system, such as within a given BSS and in neighboring BSS&#39;s, may be reduced. Such operation may be implemented in a variety of ways, including the manager/coordinator wireless communication device specifically providing respective wakeup windows for each respective SMSTA within a given wireless communication device. As can be seen with respect to the top of this diagram, an SP announcement is provided that specifies the respective times at which different respective SMSTA&#39;s are to awaken. As can be seen, one or more given SP announcements may be used to specify more than one wakeup time for more than one SMSTA, respectively. Alternatively, a manager/coordinator wireless communication device, such as an AP, may provide different respective communications to instruct the different respective SMSTA is to awaken at certain respective times. 
     In addition, one manner in which the possibility of collisions by different respective SMSTA&#39;s may be reduced is to increase the listen interval for given respective SMSTA&#39;s after wake before transmission to provide for improved performance including helping to reduce hidden STA collisions. In one embodiment, the listen interval may be increased uniformly for each respective SMSTA. In another embodiment, different respective listen intervals may be specified respectively for different SMSTA&#39;s (e.g., a first listen window for a first SMSTA, a second listen window for second SMSTA, etc.). Of course, the respective values and durations of these respective listen windows may be adapted and/or modified based on any of a number of considerations. As may be seen with respect to the bottom portion of the diagram, there may be respective periods of inactivity between the wakeup windows of different respective SMSTA&#39;s. The duration of any one given period of inactivity may be fixed or predetermined, or indefinite such that the period of inactivity ends upon a given condition being met or the occurrence of a given event. 
       FIG. 26  illustrates an embodiment  2600  of one wireless communication device (e.g., an access point (AP), or a wireless station (STA) operating as an AP, etc.) providing medium control during respective wakeup windows. As can be seen with respect to the operation in accordance with this diagram, more than one STA and/or SMSTA may be grouped together and operative in accordance with a given wakeup time. For example, a group of STA&#39;s and/or SMSTA&#39;s may be scheduled wake up at or around approximately the same time. In some embodiments, a manager/coordinator wireless communication device, such as an AP, may control the communication medium when such a group of STA&#39;s and/or SMSTA&#39;s awake. That is to say, such a manager/coordinator wireless communication device may serve as the controller and coordinator of access to the communication medium. In some embodiments, such a manager/coordinator wireless communication device may operate by transmitting one or more polling/scheduling frames to the other wireless communication devices within the system. By having such a coordinated approach in which a manager/coordinator wireless communication device performs such options, the wait time needed before a waking STA may effectuate transmission or receiving of information/signals may be reduced. 
     In addition, by distributing the respective wakeup times of the SMSTA&#39;s, assistance and improvement may be achieved with respect to synchronization among the various wireless communication devices. For example, in an embodiment in which a manager/coordinator wireless communication device, such as an AP, is implemented to provide respective wakeup times for each respective SMSTA, the manager/coordinator wireless communication device may be implemented to distribute the respective wake up times for the respective SMSTAs in order to reduce probability of any one given SMSTA waking and finding the communication medium BUSY. In other words, an AP may be implemented to distribute the respective wakeup times for the SMSTA&#39;s an effort to reduce collision probability between SMSTAs and other STAs and among SMSTAs themselves. 
     Also, such a manager/coordinator wireless communication device, such as an AP, may be implemented to provide NEXT_WAKE_TT for each STA in one or more response frames. Generally speaking, such a manager/coordinator wireless communication device may provide any desired additional information that may be useful and/or needed by one or more of the other wireless communication devices within one or more response frames. For example, with respect to synchronization, and AP may provide a timestamp associated with the internal clock of the AP in a response frames given to an STA. As may be understood, when considering an SMSTA clock which may have an accuracy of approximately ±20 parts per million (ppm), then by providing a 15 min. wake interval, there may be as much as a ±18 ms error associated therewith 
     The value NEXT_WAKE_TT=Next Wake Target Time, and this corresponds to the preferred time for next wake for the receiving SMSTA. This value, NEXT_WAKE_TT, may be embedded within an acknowledgment (ACK) or DATA response to an uplink transmission from an SMSTA. The manager/coordinator wireless communication device, such as an AP, maybe implemented to provide different respective NEXT_WAKE_TT for each respective STA in order to space out wakes and transmission attempts. As may be understood by providing specifically tailored and different, respective values for each respective STA, the possibility of collisions may be reduced, and the latency associated with the communication medium may also be reduced. 
     If desired, the respective wakeup times associated with the other wireless communication devices may be specifically made during times other than those known to be associated with high traffic or high-volume on the communication medium. For example, such a manager/coordinator wireless communication device, such as an AP, can put the respective STA wake times as being specified so that they are away from other known high-occupancy times (e.g., periods in which there is a relatively high degree of confidence that there is high traffic, high volume, etc. on the communication medium, such as during particular hours of the evening when it may be understood that people are at home, on the Internet, etc.). 
     In addition, a client or wireless communication device (e.g., STA) may be implemented to transmit a field containing a desired or target wake time (TWT), such as TWT=NEXT_WAKE_TT. Such a time may be specified and/or requested by a given wireless communication device (e.g., STA), and a manager/coordinator wireless communication device (e.g., AP) may respond with an actual TWT (e.g., which, ideally, will be the same as that which was requested by the STA). A client TWT field can be implemented in accordance with any of a number of ways. For example, a TWT field may include information corresponding to a time, such as a value including a mantissa and a scaling factor. For example, one embodiment may include a six bit mantissa with a four bit scaling factor, while another embodiment may include a 10 bit mantissa and a four bit scaling factor (e.g., for indicating a number of microseconds in any of a number of different orders of magnitude and/or ranges, such as approximately 1024 μs, approximately 1,000,000 μs, approximately 1000 μs, etc.). Alternatively or in conjunction with, a TWT field may include information corresponding to class identifier (e.g., one of a number of possible classes, such as 16 different respective classes in one embodiment) with predefined respective wake intervals for those different respective classes. Alternatively or in conjunction with, such a TWT field may include information corresponding to a wake interval selector (e.g., one of a number of possible classes, such as 16 different respective classes in one embodiment) such as corresponding to a previously advertised set of wake intervals. That is to say, different respective classes may be provided different respective wake intervals (e.g., a first group or class may be implemented to send periodically after the lapse of a first period of time (Δt 1 ), a second group or class may be limited to send periodically after the lapse of a second period of time (Δt 2 ), etc.). 
     For example, such a manager/coordinator wireless communication device, such as an AP, maybe implemented to advertise a set of wake intervals with corresponding wake interval selector values to choose from in a beacon and/or a probe response, and a client or wireless communication device (e.g., STA) chooses the particular wake interval that best matches its corresponding needs and uses that corresponding weight interval selector value in its transmissions. The client or wireless communication device (e.g., STA) may be implemented to include a wake field and each of its respective transmissions as well, such that the manager/coordinator wireless communication device, such as an AP, will subsequently respond with a computed TWT. In the instance in which a client or wireless communication device (e.g., STA) is not ready to go back to sleep, or if the client/wireless communication device is one that does not go back to sleep (e.g., a non-LP STA or non-LP SMSTA, etc.), then that particular wireless communication device may send a null value, a special selector value, and/or a zero value indicating what the TWT will be. For example, such a value may be employed to indicate that that particular device does not plan to go to sleep or does not go to sleep. Also, additional information may be provided within communications from such a client or wireless communication device (e.g., STA) to indicate the tolerance associated therewith, such as in accordance with the clock employed (e.g., relatively lower accuracy, inaccurate, etc.). As an example, one or more bits may be provided to indicate the relative strictness in terms of tolerance, such as in accordance with clock synchronization. Moreover, once a given wireless communication devices awaken operative, it may correspondingly provide one or more communications informing other wireless communication devices that it is in fact wake. 
     Referring again to the distribution of the respective wakeup times of different respective wireless communication devices (e.g., STAs, SMSTAs, etc.), it is noted that often times SMSTA&#39;s do not have accurate wake times. For example, no greater than approximately 0.1 msec resolution may be expected for a given SMSTA because of duration of sleep and accuracy of crystal for clock. 
     With respect to an SMSTA transmit procedure, in order to avoid collisions of subsequent transmissions, when an SMSTA wakes up, and it is scheduled to transmit, that respective wireless communication device (e.g., SMSTA) may be implemented to listen for a period of time (e.g., Y msec) before it transmits, such as pictorially illustrated with reference to  FIG. 25 . The particular value of such a period of time, Y, may be chosen to be MAX_PPDU+SIFS to cover cases where hidden STA is common. Also, a MAX_PPDU+SIFS may be used so packet header information of a data frame or its corresponding response frame is received. This may allow the waking of an SMSTA to become aware of medium activity. 
       FIG. 27  illustrates an embodiment  2700  of respective communications between wireless communication devices in a wireless communication system. As may be understood with respect to this diagram, communications are made from a manager/coordinator wireless communication device, such as an AP, to one or more other wireless communication devices. Subsequently, as may be seen near the middle of the diagram, typically at different respective times, each respective one of the other wireless communication devices provides an upstream transmission to the manager/coordinator wireless communication device, and the manager/coordinator wireless communication device responds accordingly (e.g., such as by using a response frame, an acknowledgment (ACK), etc.). This process may be repeated at other respective times as well, as shown towards the bottom of the diagram. 
       FIG. 28  illustrates an embodiment  2800  of transmission retry of a SMSTA to another wireless communication device. Generally speaking, the operations as pictorially illustrated with respect to  FIG. 27  show successful communications between two different respective wireless communication devices; however, there may be some instances in which a given wireless communication device, such as in SMSTA, does not receive an expected response (e.g., an ACK) after it has transmitted information to the manager/coordinator wireless communication device. Generally speaking, when such an event occurs, the transmission is said to have failed and usually needs to be retried. In one embodiment, a carrier sense multiple access/collision avoidance (CSMA/CA) random backoff process may be employed after which the upstream transmission is retried. For example, a given wireless communication at SMSTA, may listen for a period of time after having performed a subsequent retransmission after having performed a CSMA/CA random backoff process in the event of failing to receive a response, and once a response has been received, then the retried transmission may be deemed as a success, and the wireless communication device may subscribe to go to sleep or perform other operations. 
     Within this as well as within other embodiments, it is noted that if a transmission is deemed to have been a failure, an alternative embodiment may also include holding on to the data associated with that failed transmission and attempting to transmit it in a subsequent transmission. As such, information associated with more than one measurement may be transmitted in a subsequent transmission (e.g., information from the prior/failed transmission [that was retained due to the failure of that prior/failed transmission] as well as information associated with the current transmission). 
       FIG. 29  illustrates an alternative embodiment  2900  of transmission retry of a SMSTA to another wireless communication device. Instead of performing a CSMA/CA random backoff process as described with respect to the previous embodiment  2800   FIG. 28 , it wireless communication device, such as an SMSTA, maybe implemented to go&#39;s to sleep for some random time period, such as R msec where R[0,WW] immediately after it has been identified that there was a transmission failure. Then, that particular wireless communication device may wake up after that time period, R msec, has elapsed, and the wireless communication device may repeat the SMSTA transmit procedure again. If desired, the duration of a respective listen window associated with the SMSTA transmit procedure being performed again may be different from a prior listen window. The particular value of WW may be chosen by a manager/coordinator wireless communication device, such as an AP, based on any of a number of considerations including the load of network overall, number of SMSTA present, overlapping BSS presence, etc. Also, the particular value of WW may be communicated during association, with management frames, and/or in accordance with other communications. 
       FIG. 30  illustrates an embodiment  3000  of one wireless communication device (e.g., an AP, or a STA operating as an AP, etc.) providing medium control in accordance with polling frames to a number of wireless communication devices (e.g., SMSTAs). As may be also understood with respect other diagrams and/or embodiments herein, a group of SMSTAs may be scheduled to wake up within a window of G msec beginning at a time WT. This value, WT, maybe implemented such that it is referenced to the TSF clock of the manager/coordinator wireless communication device, such as an AP. 
     During the window in which the SMSTAs are awake, the manager/coordinator wireless communication device (e.g., AP) may be implemented to control the communication medium by polling the respective SMSTAs for their respective data. The polling of the respective SMSTA&#39;s may be implemented any of a variety of ways. For example, the manager/coordinator wireless communication device (e.g., AP) may poll single or multiple SMSTAs with a single POLL. When multiple SMSTAs are polled, each respective SMSTA may be provided a respective start time for its transmission. Also, multiple user uplink communications (e.g., multi-user ACKs and multi-user feedback signaling may be used to provide simultaneous uplink communications from the respective wireless communication devices to the manager/coordinator wireless communication device (e.g., AP)). If a given SMSTA does not hear a poll frame, it can transmit its respective packet after the elapse of a particular period of time (e.g., Z msec) from the start of the window. 
       FIG. 31  illustrates an embodiment  3100  of synchronization (e.g., of clocks) of a number of wireless communication devices (e.g., SMSTAs). Short frames may be transmitted by a manager/coordinator wireless communication device (e.g., AP) to synchronize the SMSTAs in its respective BSS&#39;s for example, one or more synchronization frames may be implemented to include a subset of TSF bits. If desired, the number of bits depends on the typical sleep time of a given SMSTA and the expected maximum error between the SMSTA and AP clocks after that amount of sleep time has transpired. 
     If desired, a different and separately implemented frame may be transmitted for synchronization purpose only. That is to say, while various embodiments described herein are directed towards including information for use in accordance with synchronization, an independent and respective communication may be employed specifically for synchronization purposes. 
     Again, generally speaking, it is noted that any of a variety of other types of frames (e.g., including those related to acknowledgments (ACKs), polling, management, and/or other types) may be used for synchronization as well. Generally, appropriate timing information may be included within any communication transmitted between respective wireless communication devices within it wireless communication system. 
     Also, it is noted that an SMSTA with an inaccurate clock can wake at approximate time for next scheduled wake window (e.g., earlier) and listen for synchronization frames. Such an SMSTA clock (e.g., an inaccurate clock) can be corrected upon receipt of a synchronization frame, and SMSTA can return to sleep for whatever time remains before actual desired wake window begins. For example, such an SMSTA may be implemented to wake up before its respective scheduled time and to perform a re-synchronization process so that it is then properly synchronized and ready to perform its respective operations at the proper time. That is to say, if a given wireless communication device, such as an SMSTA or an LP STA is known potentially to have a clock of relatively lower accuracy, then that particular wireless communication device may be implemented to wake up before its particular scheduled time and to undergo a synchronization process so that its clock is actually synchronized (e.g., and it can then perform its respective operations at the appropriate and accurate time). 
     In addition, there may be certain wireless communication devices that are implemented to be awake all the times (e.g., such as those which are provided wall power [120 V ac, 60 Hz from an electrical outlet], including laptops, other wireless communication devices, etc.), and their respective clocks may be much more accurate than that which is included within a given wireless communication device, such as an SMSTA or an LP STA is known potentially to have a clock of relatively lower accuracy. If desired, such an SMSTA or an LP STA may use the clock of any one or more other wireless communication devices known to have a relatively accurate clock for correcting and/or synchronizing its respective clock. That is to say, non-AP STAs and SMSTAs may also participate in providing synchronization frames for waking SMSTAs. As may be understood, since all or most of the respective other wireless communication devices (e.g., STAs) transmitting synchronization frames must have accurate timing information, then any of the respective other wireless communication devices (e.g., STAs) known to have relatively accurate clocks or that currently have relatively accurate information (e.g., even considering a relatively inaccurate clock that has recently been synchronized) may effectuate transmission of one or more communications including timing and/or synchronization information therein. For example, any of the respective other wireless communication devices (e.g., STAs) transmitting synchronization frames may integrate such timing and/or synchronization information into any of a number of different types of frames or communications including data frames, response frames, and other frames. 
       FIG. 32 ,  FIG. 33A ,  FIG. 33B , and  FIG. 34  illustrate various embodiments of methods performed by one or more communication devices 
     Referring to method  3200  of  FIG. 32 , the method  3200  begins by operating a radio of the communication device to support communications with a wireless network manager, as shown in a block  3210 . The method  3200  continues by directing the communication device to enter a sleep mode for a first period of time, as shown in a block  3220 . The method  3200  then operates by awakening the communication device from the sleep mode at a specified time, as shown in a block  3230 . 
     Via at least one communication medium access option corresponding to a second period of time following the specified time such that the second period of time is relatively much shorter in duration than the first period of time by at least one order of magnitude, the method  3200  continues by identifying a third period of time and at least one wireless communication channel for the radio to make communications to the wireless network manager, as shown in a block  3240 . 
     The method  3200  then operates by operating the radio to transmit at least one of sensing and measurement related data associated with the communication device to the wireless network manager during the third period of time and via the at least one wireless communication channel, as shown in a block  3250 . 
     Referring to method  3300  of  FIG. 33A , the method  3300  begins by operating a communication device to monitor for communication activity on the at least one wireless communication channel during a period of time, as shown in a block  3310 . 
     The method  3300  continues by determining if a period of inactivity is detected within the period of time, as shown in a decision block  3320 . 
     If a period of inactivity is detected within the period of time within the decision block  3320 , then the method  3300  operates by operating a radio to transmit at least one of sensing and measurement related data associated with the communication device to the wireless network manager, as shown in a block  3330 . 
     Alternatively, if no period of inactivity is detected within the period of time within the decision block  3320 , then the method  3300  operates by ending. 
     Referring to method  3301  of  FIG. 33B , the method  3301  begins by transmitting a service period (SP) announcement to a plurality of communication devices (e.g., via at least one antenna of the communication device, such as an AP, etc.), as shown in a block  3311 . The method  3301  continues by receiving a first signal (e.g., including sensing and/or measurement related data) from a first of the plurality of communication devices during a first time period indicated within the SP announcement, as shown in a block  3321 . 
     The method  3301  then operates by receiving a second signal (e.g., including sensing and/or measurement related data) from a second of the plurality of communication devices during a second time period indicated within the SP announcement, as shown in a block  3331 . 
     Referring to method  3400  of  FIG. 34 , the method  3400  begins by transmitting a service period (SP) announcement to a plurality of communication devices (e.g., via at least one antenna of the communication device, such as an AP, etc.), as shown in a block  3410 . 
     The method  3400  continues by receiving a first set of signals (e.g., including sensing and/or measurement related data) from a first subset of the plurality of communication devices during a first time period indicated within the SP announcement, as shown in a block  3420 . In certain embodiments, the method  3400  also operates by operating the first subset of the plurality of communication devices using a first communication access option, as shown in a block  3422 . 
     The method  3400  then operates by receiving a second set of signals (e.g., including sensing and/or measurement related data) from a second subset of the plurality of communication devices during a second time period indicated within the SP announcement, as shown in a block  3430 . In certain embodiments, the method  3400  also operates by operating the second subset of the plurality of communication devices using the first communication access option or a second communication access option, as shown in a block  3432 . 
     It is also noted that the various operations and functions as described with respect to various methods herein may be performed within a wireless communication device, such as using a baseband processing module and/or a processing module implemented therein, (e.g., such as in accordance with the baseband processing module  64  and/or the processing module  50  as described with reference to  FIG. 2 ) and/or other components therein. For example, such a baseband processing module can generate such signals and frames as described herein as well as perform various operations and analyses as described herein, or any other operations and functions as described herein, etc. or their respective equivalents. 
     In some embodiments, such a baseband processing module and/or a processing module (which may be implemented in the same device or separate devices) can perform such processing to generate signals for transmission using at least one of any number of radios and at least one of any number of antennae to another wireless communication device (e.g., which also may include at least one of any number of radios and at least one of any number of antennae) in accordance with various aspects of the invention, and/or any other operations and functions as described herein, etc. or their respective equivalents. In some embodiments, such processing is performed cooperatively by a processing module in a first device, and a baseband processing module within a second device. In other embodiments, such processing is performed wholly by a baseband processing module or a processing module. 
     As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “operable to” or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item. As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal  1  has a greater magnitude than signal  2 , a favorable comparison may be achieved when the magnitude of signal  1  is greater than that of signal  2  or when the magnitude of signal  2  is less than that of signal  1 . 
     As may also be used herein, the terms “processing module”, “module”, “processing circuit”, and/or “processing unit” (e.g., including various modules and/or circuitries such as may be operative, implemented, and/or for encoding, for decoding, for baseband processing, etc.) may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, and/or processing unit may have an associated memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of the processing module, module, processing circuit, and/or processing unit. Such a memory device may be a read-only memory (ROM), random access memory (RAM), volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the Figures. Such a memory device or memory element can be included in an article of manufacture. 
     The present invention has been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claimed invention. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claimed invention. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof. 
     The present invention may have also been described, at least in part, in terms of one or more embodiments. An embodiment of the present invention is used herein to illustrate the present invention, an aspect thereof, a feature thereof, a concept thereof, and/or an example thereof. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process that embodies the present invention may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones. 
     Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art. 
     The term “module” is used in the description of the various embodiments of the present invention. A module includes a functional block that is implemented via hardware to perform one or module functions such as the processing of one or more input signals to produce one or more output signals. The hardware that implements the module may itself operate in conjunction software, and/or firmware. As used herein, a module may contain one or more sub-modules that themselves are modules. 
     While particular combinations of various functions and features of the present invention have been expressly described herein, other combinations of these features and functions are likewise possible. The present invention is not limited by the particular examples disclosed herein and expressly incorporates these other combinations. 
     Mode Selection Tables: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 2.4 GHz, 20/22 MHz channel BW, 54 Mbps max bit rate 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Code 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Rate 
                 Modulation 
                 Rate 
                 NBPSC 
                 NCBPS 
                 NDBPS 
                 EVM 
                 Sensitivity 
                 ACR 
                 AACR 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Barker 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 1 
                 BPSK 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                   
                 Barker 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 2 
                 QPSK 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 5.5 
                 CCK 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 6 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
                 −5 
                 −82 
                 16 
                 32 
               
               
                 9 
                 BPSK 
                 0.75 
                 1 
                 48 
                 36 
                 −8 
                 −81 
                 15 
                 31 
               
               
                 11 
                 CCK 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 12 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
                 −10 
                 −79 
                 13 
                 29 
               
               
                 18 
                 QPSK 
                 0.75 
                 2 
                 96 
                 72 
                 −13 
                 −77 
                 11 
                 27 
               
               
                 24 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
                 −16 
                 −74 
                 8 
                 24 
               
               
                 36 
                 16-QAM 
                 0.75 
                 4 
                 192 
                 144 
                 −19 
                 −70 
                 4 
                 20 
               
               
                 48 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
                 −22 
                 −66 
                 0 
                 16 
               
               
                 54 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
                 −25 
                 −65 
                 −1 
                 15 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Channelization for Table 1 
               
            
           
           
               
               
               
            
               
                   
                   
                 Frequency 
               
               
                   
                 Channel 
                 (MHz) 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 1 
                 2412 
               
               
                   
                 2 
                 2417 
               
               
                   
                 3 
                 2422 
               
               
                   
                 4 
                 2427 
               
               
                   
                 5 
                 2432 
               
               
                   
                 6 
                 2437 
               
               
                   
                 7 
                 2442 
               
               
                   
                 8 
                 2447 
               
               
                   
                 9  
                 2452 
               
               
                   
                 10 
                 2457 
               
               
                   
                 11 
                 2462 
               
               
                   
                 12 
                 2467 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Power Spectral Density (PSD)  
               
               
                 Mask for Table 1 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 PSD Mask 
                 1 
               
               
                   
                 Frequency Offset 
                 dBr 
               
               
                   
                 −9 MHz to 9 MHz 
                 0 
               
               
                   
                 +/− 11 MHz 
                 −20 
               
               
                   
                 +/− 20 MHz 
                 −28 
               
               
                   
                 +/− 30 MHz and greater 
                 −50 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 5 GHz, 20 MHz channel BW, 54 Mbps max bit rate 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Code 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Rate 
                 Modulation 
                 Rate 
                 NBPSC  
                 NCBPS 
                 NDBPS 
                 EVM 
                 Sensitivity 
                 ACR 
                 AACR 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
                 −5 
                 −82 
                 16 
                 32 
               
               
                 9 
                 BPSK 
                 0.75 
                 1 
                 48 
                 36 
                 −8 
                 −81 
                 15 
                 31 
               
               
                 12 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
                 −10 
                 −79 
                 13 
                 29 
               
               
                 18 
                 QPSK 
                 0.75 
                 2 
                 96 
                 72 
                 −13 
                 −77 
                 11 
                 27 
               
               
                 24 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
                 −16 
                 −74 
                 8 
                 24 
               
               
                 36 
                 16-QAM 
                 0.75 
                 4 
                 192 
                 144 
                 −19 
                 −70 
                 4 
                 20 
               
               
                 48 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
                 −22 
                 −66 
                 0 
                 16 
               
               
                 54 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
                 −25 
                 −65 
                 −1 
                 15 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Channelization for Table 4 
               
            
           
           
               
               
            
               
                 Frequency 
                 Frequency 
               
            
           
           
               
               
               
               
               
               
            
               
                 Channel 
                 (MHz) 
                 Country 
                 Channel 
                 (MHz)  
                 Country 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 240 
                 4920 
                 Japan 
                   
                   
                   
               
               
                 244 
                 4940 
                 Japan 
                   
                   
                   
               
               
                 248 
                 4960 
                 Japan 
                   
                   
                   
               
               
                 252 
                 4980 
                 Japan 
                   
                   
                   
               
               
                 8 
                 5040 
                 Japan 
                   
                   
                   
               
               
                 12 
                 5060 
                 Japan 
                   
                   
                   
               
               
                 16 
                 5080 
                 Japan 
                   
                   
                   
               
               
                 36 
                 5180 
                 USA/Europe 
                 34 
                 5170  
                 Japan 
               
               
                 40 
                 5200 
                 USA/Europe 
                 38 
                 5190  
                 Japan 
               
               
                 44 
                 5220 
                 USA/Europe 
                 42 
                 5210  
                 Japan 
               
               
                 48 
                 5240 
                 USA/Europe 
                 46 
                 5230  
                 Japan 
               
               
                 52 
                 5260 
                 USA/Europe 
                   
                   
                   
               
               
                 56 
                 5280 
                 USA/Europe 
                   
                   
                   
               
               
                 60 
                 5300 
                 USA/Europe 
                   
                   
                   
               
               
                 64 
                 5320 
                 USA/Europe 
                   
                   
                   
               
               
                 100 
                 5500 
                 USA/Europe 
                   
                   
                   
               
               
                 104 
                 5520 
                 USA/Europe 
                   
                   
                   
               
               
                 108 
                 5540 
                 USA/Europe 
                   
                   
                   
               
               
                 112 
                 5560 
                 USA/Europe 
                   
                   
                   
               
               
                 116 
                 5580 
                 USA/Europe 
                   
                   
                   
               
               
                 120 
                 5600 
                 USA/Europe 
                   
                   
                   
               
               
                 124 
                 5620 
                 USA/Europe 
                   
                   
                   
               
               
                 128 
                 5640 
                 USA/Europe 
                   
                   
                   
               
               
                 132 
                 5660 
                 USA/Europe 
                   
                   
                   
               
               
                 136 
                 5680 
                 USA/Europe 
                   
                   
                   
               
               
                 140 
                 5700 
                 USA/Europe 
                   
                   
                   
               
               
                 149 
                 5745 
                 USA 
                   
                   
                   
               
               
                 153 
                 5765 
                 USA 
                   
                   
                   
               
               
                 157 
                 5785 
                 USA 
                   
                   
                   
               
               
                 161 
                 5805 
                 USA 
                   
                   
                   
               
               
                 165 
                 5825 
                 USA 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 2.4 GHz, 20 MHz channel BW, 192 Mbps max bit rate 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 TX 
                 ST 
                   
                   
                   
                   
                   
               
               
                   
                 An- 
                 Code 
                 Mod- 
                 Code  
                   
                   
                   
               
               
                 Rate 
                 tennas 
                 Rate 
                 ulation 
                 Rate 
                 NBPSC 
                 NCBPS 
                 NDBPS 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 12 
                 2 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 24 
                 2 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 48 
                 2 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 96 
                 2 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 108 
                 2 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                 18 
                 3 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 36 
                 3 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 72 
                 3 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 144 
                 3 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 162 
                 3 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                 24 
                 4 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 48 
                 4 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 96 
                 4 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 192 
                 4 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 216 
                 4 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Channelization for Table 6 
               
            
           
           
               
               
               
            
               
                   
                 Channel 
                 Frequency (MHz) 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 1 
                 2412 
               
               
                   
                 2 
                 2417 
               
               
                   
                 3 
                 2422 
               
               
                   
                 4 
                 2427 
               
               
                   
                 5 
                 2432 
               
               
                   
                 6 
                 2437 
               
               
                   
                 7 
                 2442 
               
               
                   
                 8 
                 2447 
               
               
                   
                 9  
                 2452 
               
               
                   
                 10 
                 2457 
               
               
                   
                 11 
                 2462 
               
               
                   
                 12 
                 2467 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 5 GHz, 20 MHz channel BW, 192 Mbps max bit rate 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 ST  
                   
                   
                   
                   
                   
               
               
                   
                 TX 
                 Code 
                 Mod- 
                 Code 
                   
                   
                   
               
               
                 Rate 
                 Antennas 
                 Rate 
                 ulation 
                 Rate 
                 NBPSC 
                 NCBPS 
                 NDBPS 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 12 
                 2 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 24 
                 2 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 48 
                 2 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 96 
                 2 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 108 
                 2 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                 18 
                 3 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 36 
                 3 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 72 
                 3 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 144 
                 3 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 162 
                 3 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                 24 
                 4 
                 1 
                 BPSK 
                 0.5 
                 1 
                 48 
                 24 
               
               
                 48 
                 4 
                 1 
                 QPSK 
                 0.5 
                 2 
                 96 
                 48 
               
               
                 96 
                 4 
                 1 
                 16-QAM 
                 0.5 
                 4 
                 192 
                 96 
               
               
                 192 
                 4 
                 1 
                 64-QAM 
                 0.666 
                 6 
                 288 
                 192 
               
               
                 216 
                 4 
                 1 
                 64-QAM 
                 0.75 
                 6 
                 288 
                 216 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 channelization for Table 8 
               
            
           
           
               
               
            
               
                 Frequency 
                 Frequency 
               
            
           
           
               
               
               
               
               
               
            
               
                 Channel 
                 (MHz) 
                 Country 
                 Channel 
                 (MHz) 
                 Country 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 240 
                 4920 
                 Japan 
                   
                   
                   
               
               
                 244 
                 4940 
                 Japan 
                   
                   
                   
               
               
                 248 
                 4960 
                 Japan 
                   
                   
                   
               
               
                 252 
                 4980 
                 Japan 
                   
                   
                   
               
               
                 8 
                 5040 
                 Japan 
                   
                   
                   
               
               
                 12 
                 5060 
                 Japan 
                   
                   
                   
               
               
                 16 
                 5080 
                 Japan 
                   
                   
                   
               
               
                 36 
                 5180 
                 USA/Europe 
                 34 
                 5170 
                 Japan 
               
               
                 40 
                 5200 
                 USA/Europe 
                 38 
                 5190 
                 Japan 
               
               
                 44 
                 5220 
                 USA/Europe 
                 42 
                 5210 
                 Japan 
               
               
                 48 
                 5240 
                 USA/Europe 
                 46 
                 5230 
                 Japan 
               
               
                 52 
                 5260 
                 USA/Europe 
                   
                   
                   
               
               
                 56 
                 5280 
                 USA/Europe 
                   
                   
                   
               
               
                 60 
                 5300 
                 USA/Europe 
                   
                   
                   
               
               
                 64 
                 5320 
                 USA/Europe 
                   
                   
                   
               
               
                 100 
                 5500 
                 USA/Europe 
                   
                   
                   
               
               
                 104 
                 5520 
                 USA/Europe 
                   
                   
                   
               
               
                 108 
                 5540 
                 USA/Europe 
                   
                   
                   
               
               
                 112 
                 5560 
                 USA/Europe 
                   
                   
                   
               
               
                 116 
                 5580 
                 USA/Europe 
                   
                   
                   
               
               
                 120 
                 5600 
                 USA/Europe 
                   
                   
                   
               
               
                 124 
                 5620 
                 USA/Europe 
                   
                   
                   
               
               
                 128 
                 5640 
                 USA/Europe 
                   
                   
                   
               
               
                 132 
                 5660 
                 USA/Europe 
                   
                   
                   
               
               
                 136 
                 5680 
                 USA/Europe 
                   
                   
                   
               
               
                 140 
                 5700 
                 USA/Europe 
                   
                   
                   
               
               
                 149 
                 5745 
                 USA 
                   
                   
                   
               
               
                 153 
                 5765 
                 USA 
                   
                   
                   
               
               
                 157 
                 5785 
                 USA 
                   
                   
                   
               
               
                 161 
                 5805 
                 USA 
                   
                   
                   
               
               
                 165 
                 5825 
                 USA 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 5 GHz, with 40 MHz channels and max bit rate of 486 Mbps 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 TX 
                 ST Code 
                   
                 Code 
                   
               
               
                 Rate 
                 Antennas 
                 Rate 
                 Modulation 
                 Rate 
                 NBPSC 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                  13.5 Mbps 
                 1 
                 1 
                 BPSK 
                 0.5 
                 1 
               
               
                   27 Mbps 
                 1 
                 1 
                 QPSK 
                 0.5 
                 2 
               
               
                   54 Mbps 
                 1 
                 1 
                 16-QAM 
                 0.5 
                 4 
               
               
                   108 Mbps 
                 1 
                 1 
                 64-QAM 
                 0.666 
                 6 
               
               
                 121.5 Mbps 
                 1 
                 1 
                 64-QAM 
                 0.75 
                 6 
               
               
                   27 Mbps 
                 2 
                 1 
                 BPSK 
                 0.5 
                 1 
               
               
                   54 Mbps 
                 2 
                 1 
                 QPSK 
                 0.5 
                 2 
               
               
                   108 Mbps 
                 2 
                 1 
                 16-QAM 
                 0.5 
                 4 
               
               
                   216 Mbps 
                 2 
                 1 
                 64-QAM 
                 0.666 
                 6 
               
               
                   243 Mbps 
                 2 
                 1 
                 64-QAM 
                 0.75 
                 6 
               
               
                  40.5 Mbps 
                 3 
                 1 
                 BPSK 
                 0.5 
                 1 
               
               
                   81 Mbps 
                 3 
                 1 
                 QPSK 
                 0.5 
                 2 
               
               
                   162 Mbps 
                 3 
                 1 
                 16-QAM 
                 0.5 
                 4 
               
               
                   324 Mbps 
                 3 
                 1 
                 64-QAM 
                 0.666 
                 6 
               
               
                 365.5 Mbps 
                 3 
                 1 
                 64-QAM 
                 0.75 
                 6 
               
               
                   54 Mbps 
                 4 
                 1 
                 BPSK 
                 0.5 
                 1 
               
               
                   108 Mbps 
                 4 
                 1 
                 QPSK 
                 0.5 
                 2 
               
               
                   216 Mbps 
                 4 
                 1 
                 16-QAM 
                 0.5 
                 4 
               
               
                   432 Mbps 
                 4 
                 1 
                 64-QAM 
                 0.666 
                 6 
               
               
                   486 Mbps 
                 4 
                 1 
                 64-QAM 
                 0.75 
                 6 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 11 
               
               
                   
               
               
                 Power Spectral Density (PSD)  
               
               
                 mask for Table 10 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 PSD Mask 
                 2 
               
               
                   
                 Frequency Offset 
                 dBr 
               
               
                   
                 −19 MHz to 19 MHz 
                 0 
               
               
                   
                 +/− 21 MHz 
                 −20 
               
               
                   
                 +/− 30 MHz 
                 −28 
               
               
                   
                 +/− 40 MHz and greater 
                 −50 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                 Channelization for Table 10 
               
            
           
           
               
               
            
               
                 Frequency 
                 Frequency 
               
            
           
           
               
               
               
               
               
               
            
               
                 Channel  
                 (MHz) 
                 Country  
                 Channel 
                 (MHz) 
                 County 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 242 
                 4930 
                 Japan 
                   
                   
                   
               
               
                 250 
                 4970 
                 Japan 
                   
                   
                   
               
               
                 12 
                 5060 
                 Japan 
                   
                   
                   
               
               
                 38 
                 5190 
                 USA/Europe 
                 36 
                 5180 
                 Japan 
               
               
                 46 
                 5230 
                 USA/Europe 
                 44 
                 5520 
                 Japan 
               
               
                 54 
                 5270 
                 USA/Europe 
                   
                   
                   
               
               
                 62 
                 5310 
                 USA/Europe 
                   
                   
                   
               
               
                 102 
                 5510 
                 USA/Europe 
                   
                   
                   
               
               
                 110 
                 5550 
                 USA/Europe 
                   
                   
                   
               
               
                 118 
                 5590 
                 USA/Europe 
                   
                   
                   
               
               
                 126 
                 5630 
                 USA/Europe 
                   
                   
                   
               
               
                 134 
                 5670 
                 USA/Europe 
                   
                   
                   
               
               
                 151 
                 5755 
                 USA 
                   
                   
                   
               
               
                 159 
                 5795 
                 USA