Patent Publication Number: US-11050596-B2

Title: Devices, systems and methods for narrow band communications within protocol having frequency multiplexing

Description:
This application is a Continuation of U.S. patent application Ser. No. 16/366,695, filed on Mar. 27, 2019, which is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to wireless networks, and more particularly to extending a range of a wireless network. 
     BACKGROUND 
     Conventional WLAN devices can establish communication connections over a number of channels, each occupying a different frequency bandwidth. To increase bandwidth efficiency, wireless standard have been developed that frequency divide an available channel to enable multi-user multiple-input multiple output (MU-MIMO) communications over the same channel. 
       FIG. 10  is a diagram showing transmissions according to the IEEE 802.11ax standard that includes MU-MIMO communications.  FIG. 10  shows a conventional packet that can be transmitted over a channel having a bandwidth of about 20 MHz. The conventional packet can begin with a legacy preamble followed by a high efficiency (HE) preamble. Subsequently, data for different destinations can be transmitted on different resource units (RUs), which can each occupy a different portion of the channel bandwidth. Orthogonal frequency division multiple access modulation is used to transmit different data streams on the separate RUs in parallel with one another. 
     While MU-MIMO capabilities can make better use of available spectra, any ability to extend a communication range in a wireless device could further improve the performance of a wireless network and/or enable new applications for wireless networks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A to 1E  are diagrams of systems and operations according to embodiments. 
         FIG. 2A to 2C  are diagrams of transmissions and transmission data formats according to embodiments. 
         FIG. 3A  is a block diagram of a device according to an embodiment.  FIG. 3B  is a block diagram of a combination device according to an embodiment. 
         FIGS. 4A and 4B  are block diagrams of modulation and demodulation circuits that can be included in embodiments.  FIG. 4C  is a diagram of transmission circuits that can be included in embodiments. 
         FIG. 5  is a flow diagram of a method for an access point device (AP) according to an embodiment. 
         FIG. 6  is a flow diagram of a method of an AP according to another embodiment. 
         FIG. 7  is a diagram of a device according to another embodiment. 
         FIG. 8  is a diagram of a system according to another embodiment. 
         FIG. 9  is a diagram of a system according to another embodiment. 
         FIG. 10  is a diagram of a conventional packet format. 
     
    
    
     DETAILED DESCRIPTION 
     According to embodiments, a wireless communication device can transmit packet data with a first preamble over a channel followed by transmissions in a number of resource units (RUs), that can be portions of the channel. A narrow band packet, including a narrow band preamble, can be transmitted in one of the RUs. 
     According to embodiments, one or more data streams can be transmitted in the RUs in parallel with the narrow band packet. The data streams do not include preambles and can be for destinations different from that of the narrow band packet. 
     According to embodiments, transmission over the RUs can be according to an orthogonal frequency division multiple access (OFDMA) modulation. 
     In some embodiments, a narrow band packet can be transmitted with a higher power spectral density (PSD) than the first preamble, and thus reach a greater range. 
     In some embodiments, the data in a narrow band packet can enable processing gains as compared to data transmitted across the full channel. Such a feature can enable the narrow band packet to be received at greater ranges. 
       FIGS. 1A to 1C  are a sequence of block diagrams of a system  100  and operations according to embodiments. A system  100  can include an access point device (AP)  102 , first station devices  104 - 0 / 1  and a second station device  108 . An AP  102  can connect various station devices ( 104 - 0 / 1 ,  108 ) in a network. While devices are referred to as APs and station devices, this should not be construed as implying any particular network topology or communication protocol. 
     Referring to  FIG. 1A , AP  102  can make a transmission  112 - 0  that includes a full band preamble  114  followed by data transmitted in multiple sub-bands in parallel with one another ( 116 - 0  to - 3 ). Sub-band transmissions ( 116 - 0  to - 3 ) can occur in different portions of a channel used to transmit full band preamble  114 . In some embodiments, frequency multiplexing can be used to divide data sets into different sub-band transmissions ( 116 - 0  to - 3 ). Channel transmissions can have a range  106 . 
     Referring still to  FIG. 1A , because first station devices  104 - 0 / 1  are within range  106 , first station devices  104 - 0 / 1  can detect the full band preamble  114  and receive transmission  112 - 0 . Each first station device ( 104 - 0 / 1 ) can de-multiplex a sub-band transmissions to receive the data sent therein. In  FIG. 1A , first station device  104 - 0  is the destination for sub-band transmission  116 - 0 , while first station device  104 - 1  is the destination for sub-band transmission  116 - 2 . 
     As represented by transmission  112 - 1 , full band preamble  114  cannot be detected and/or decoded beyond range  106 . Accordingly, second station device  108  cannot successfully receive the transmission  112 - 0  from AP  102 . 
     Referring to  FIG. 1B , AP  102  can make an extended range transmission  118 - 0 . 
     An extended range transmission  118 - 0  can include a full channel preamble  114  followed by a narrow band packet  120  included in one of the sub-bands. A narrow band packet  120  can include a portion (e.g., preamble) to signal the narrow band packet to a receiving device. A narrow band packet  120  can have a greater range than a full channel transmission (e.g., preamble  114 ). Such greater range can arise for various reasons, including but not limited to: the environment (i.e., the environment favors the sub-band over other portions of the channel), transmission power (i.e., the narrow band packet can be transmitted at a higher PSD than the full channel preamble  114 ), or packet format (i.e., the narrow band preamble packet data enables processing gains over full channel transmissions). 
     Referring still to  FIG. 1B , as represented by transmission  118 - 1 , beyond range  106 , the full channel preamble  114  (and possibly some of the other sub-bands) cannot be detected or decoded. However, second station device  108  can be monitoring the sub-band on which the narrow band packet  120  is transmitted. Due to the extended range of narrow band packet  120 , second station device  108  can successfully receive and decode the narrowband packet  120 . It is understood that such an operation can occur without using any of the full channel preamble  114 . 
     Referring to  FIG. 1C , following the receipt of a narrow band packet  120  from AP  102 , second station device  108  can transmit a narrow band response  122 . Narrow band response  122  can be transmitted in the same sub-band as the narrow band packet  120  or can be transmitted in some other narrow band (i.e., a frequency band smaller than the channel used for the full channel preamble  114 ). 
     A response  122  can have a larger range than a channel (e.g., full band) transmission, or AP  102  can be configured to receive signals at greater ranges. Consequently, AP  102  can receive the response  122 . According to the response  122  (or by further long range handshaking with second station device  108 ), AP  102  and second station device  108  can establish one or more narrow bands (e.g., sub-bands) for communication. 
     Referring to  FIG. 1D  a block diagram shows a system  100  and operations according to additional embodiments. A system  100  can include items like those of  FIGS. 1A to 1C , and like items are referred to by the same reference character. 
     In  FIG. 1D , an AP  102  can make a transmission  124 - 0  that includes a full channel preamble  114  followed by data in multiple sub-band transmissions ( 116 - 0 ,  116 - 2 / 3 ), which are in parallel with a narrow band packet  120 . First station devices  104 - 0 / 1  can be configured to detect full channel preamble  114  and subsequently extract data values from sub-bands  116 - 0  and  116 - 2 . 
     Referring still to  FIG. 1D , as represented by transmission  124 - 1 , a full channel preamble  114  and one or all of the sub-band transmissions ( 116 - 0 ,  116 - 2 / 3 ) are not detectable/decodable beyond range  106 . However, second device  108  can be configured to monitor the sub-band on which narrow band packet  120  is transmitted. Due to the extended range of narrow band packet  120 , second station device  108  can successfully receive and decode the narrowband packet  120 . Subsequently, a second station device  108  can transmit a response, as described with reference to  FIG. 1C . 
     While embodiments have shown transmissions in which a single sub-band can be used for extending a transmission range, other embodiments can use more than one sub-band. Such an arrangement is shown in  FIG. 1E . 
     Referring to  FIG. 1E  a block diagram shows a system  100  and operations according to additional embodiments. A system  100  can include items like those of  FIG. 1D , and like items are referred to by the same reference character. 
       FIG. 1E  differs from  FIG. 1D  in that a transmission  124 - 2  from an AP  102  can include multiple narrow band packets in different sub-bands. In the particular example show, two narrow band packets  120 - 0 / 1  can be transmitted across different sub-bands. As represented by transmission  124 - 3 , a full channel preamble  114  and one or all of the sub-band transmissions ( 116 - 0 / 2 ) are not detectable/decodable beyond range  106 . However, second station device  108 - 0  can be configured to monitor and receive data on the sub-band corresponding to narrow band packet  120 - 0 , while second station device  108 - 1  can be configured to monitor and receive data on the sub-band corresponding to narrow band packet  120 - 1 . Subsequently, a second station devices  108 - 0 / 1  can transmit responses, as described with reference to  FIG. 1C . 
     While transmissions according to embodiments can take any suitable form, particular transmission structures will now be described. 
       FIG. 2A  shows a transmission  212  according an embodiment. It is understood the data for such a transmission can be stored as data in buffer circuits or the like, then subsequently modulated into the channel and sub-bands as shown. Similarly, at least a narrow band packet portion (e.g.,  220 ) can be demodulated and stored as data in buffer circuits, or the like. Thus, the transmission should not be construed as limited to an intangible signal. 
     Referring still to  FIG. 2A , a transmission  212  can include a full channel preamble  214  followed by a narrow band packet  220 . A full channel preamble  214  can be transmitted across a channel  215  that extends from some base frequency (f_base) by some bandwidth amount (BW). According to embodiments, BW can be at least 20 MHz. A full channel preamble  214  can include a first portion  214 - 0  and a second portion  214 - 1 . Such different portions  214 - 0 / 1  can be used to signal different transmission methods. In the embodiment shown, first portion  214 - 0  can be a legacy preamble while second portion  214 - 1  can be a high efficiency preamble. In some embodiments, full channel preamble  214  can take the form of a preamble transmitted according to the IEEE 802.12ax standard. 
     Referring still to  FIG. 2A , following full channel preamble  214 , a transmission  212  can include a narrow band packet  220 . A narrow band packet  220  can include one or more portions that can distinguish it as an individual packet of its own. In some embodiments, a narrow band packet  220  can include its own preamble  222 , data  224  and a packet extension field  226 . Accordingly, a narrow band packet  220  can be detected regardless, or without use of, full channel preamble  214 . A narrow band packet  220  is transmitted across a smaller frequency band  217  than full channel  215 . According to embodiments, frequency band  217  can be no more than about 50% of channel bandwidth  215 , no more than about 25% of channel bandwidth  215 , or no more than about 10% of channel bandwidth  215 . 
     In some embodiments, narrow band packet  220  can enable a greater transmission range than full channel preamble  214  (or other full channel transmissions). In some embodiments, a narrow band packet  220  can be transmitted with a greater PSD than full channel signals. In addition or alternatively, a narrow band packet  220  can enable greater range through packet structure (i.e., processing gains), including but not limited to: longer training fields, data repetition, slower data transmission rates, larger error detection and correction codes. 
     It is noted that a narrow band packet  220  can have a greater PSD than a full channel preamble  214  by transmitting at a same power (but over a smaller range of frequencies). 
       FIG. 2B  shows a transmission  224  according another embodiment. As in the case of  FIG. 2A , such a transmission should not be construed as being limited to an intangible signal. A transmission  224  can include a full channel preamble  214  as in the case of  FIG. 2A . 
     Unlike  FIG. 2A , in  FIG. 2B  a full channel preamble  214  can be followed by a narrow band packet  220 ′ transmitted in parallel with data streamed over one or more resource units (RUx, RUy, RUz) which occupy other portions of channel bandwidth  215 . In some embodiments, a transmission  224  can be made with a frequency division operation that can transmit in parallel over a number of different RUs of different bandwidth. A narrow band packet  220 ′ can be transmitted in an RU having a smallest bandwidth. In some embodiments, RUs can take the form of RUs of the IEEE 802.12ax standard. 
     While a range of narrow band packet  220 ′ can be greater than full channel transmissions according to any of the embodiments described herein, in some embodiments the longer range of narrow band packet  220 ′ can be achieved by packet structure as described herein, or equivalents (i.e., processing gains). 
     Referring to  FIG. 2C , a narrow band preamble  222 ′ according to an embodiment is shown in a diagram. A narrow band preamble  222 ′ can include a short training field (NB STF)  220 - 0 , a long training field (NB LTF)  222 - 1 , and a signaling field (NB SIG)  222 - 2 . In some embodiments, NB STF  220 - 0  can be used by a station device to detect the narrow band packet and determine a coarse frequency offset for receiving the narrow band packet. NB LTF  220 - 1  can be used by a station device for signal synchronization and fine frequency offset. NB SIG  220 - 2  can be used by a station device to determine a length of the narrow band packet, as well as provide more information about the packet (e.g., modulation information, etc.). It is understood that the various fields of a narrow band preamble  222 ′ can be transmitted across the sub-band (e.g.,  217 ), which is smaller than the channel bandwidth ( 215 ). 
       FIG. 3A  is a block diagram of a device  330  according to an embodiment. In some embodiments, device  330  can be one particular implementation of an AP like that shown as  102  in  FIGS. 1A to 1E . Device  330  can transmit messages having a leading full channel preamble, followed by a narrow band packet in a frequency multiplexed sub-band. 
     A device  330  can include communication circuits  334 , controller  338 , radio circuits  335 , and input/output (I/O) circuits  332 . Communication circuits  334  can enable operations in one or more channels, as well as control of data transmitted in parallel on sub-bands. Sub-bands can have a frequency range of less than 20 MHz. In some embodiments, sub-bands can correspond to RUs of the IEEE 802.11ax standard, or an equivalent standard that can divide channels into sub-bands. Communication circuits  334  can include WLAN circuits, including a WiFi control circuit  334 - 0  and WiFi media access control (MAC) circuits  334 - 1 . WLAN circuits can operate in any suitable band, including a 2.4 GHz band, 5.0 GHz band and/or 6.0 GHz band. In some embodiments, WLAN circuits can be compatible with a wireless IEEE 802.11 standard, such as the IEEE 802.11ax standard. In addition, communication circuits  334  can include sub-band control circuits  336 . Sub-band control circuits  336  can enable narrow band packets to be inserted into one or more sub-bands and/or the generation of a narrow band preamble on a sub-band. 
     Radio circuits  335  can include circuits for receiving and transmitting signals according to at least one protocol over one or more channels and corresponding sub-bands. 
     A controller  338  can control transmissions by communication circuits  334 . In some embodiments, a controller  338  can include circuits (or instructions executable by circuits) for generating a narrow band packet  340 . This can include the generation of a narrow band preamble. In the particular embodiment, shown, controller  338  includes a processor section  338 - 0  and a memory section  338 - 1 . 
     In some embodiments, device  330  can be an integrated circuit device, with the various portions being included in one integrated circuit package or formed in a same integrated circuit substrate. 
       FIG. 3B  is a block diagram of a combination device  330 ′ according to an embodiment. A combination device  330 ′ can include wireless circuits for operating in a WLAN mode which can insert narrow band packets into sub-bands, as well as a Bluetooth (BT) mode. Combination device  330 ′ can include sections like those shown in  FIG. 3A , including first communication circuits  334 - 0 , which can correspond to those shown as  334  in  FIG. 3A . Other like sections are referred to by the same reference characters. 
     In addition, combination device  330 ′ can include second communication circuits  334 - 1 . Second communication circuits  344 - 1  can be BT circuits including BT control circuits  344 - 0  and BT baseband circuits  344 - 1 . BT circuits can operate in a 2.4 GHz band according to a BT standard. 
     In some embodiments, device  330 ′ can be an integrated circuit device, as described herein. 
       FIGS. 4A and 4B  show examples of modulation and demodulation circuits that can be included in embodiments.  FIG. 4A  shows a modulation path  446  that can include a narrow band packet insertion section  448 , a modulation section  450 , a serial to parallel converter (SP)  452 , a transmit section  454 , and an antenna system  456 . A packet insertion section  448  can include circuits that provide a stream of bits or symbols for transmission over multiplexed sub-bands. Packet insertion section  448  can enable data for a narrow band packet to be inserted into a symbol/bit stream so that it is transmitted on the desired sub-band after multiplexing. In some embodiments, such narrow band packet data can include values that will result in generation of a desired narrow band preamble. However, in other embodiments, other sections of modulation path  446  can generate a narrow band preamble. 
     Modulation section  450  can modulate a symbol/bit stream from packet insertion section  448  according to a predetermined method. In some embodiments, modulation section  450  can create a desired narrow band preamble that will appear on the sub-band for the narrow band packet. However, in other embodiments, other sections can generate a narrow band preamble. 
     SP  452  can convert symbol/bit stream into parallel streams, each corresponding to a different sub-band. Such parallel streams can then be transmitted in parallel over different sub-bands by transmit section  454 . In some embodiments, transmit section  454  can generate a desired narrow band preamble in the sub-band containing the narrow band packet. 
     In some embodiments, modulation path  446  can use orthogonal frequency-division multiple access modulation (OFDMA) to create the parallel sub-bands. 
       FIG. 4B  shows a demodulation path  460  that can include antenna system  456 , receive section  458 , demodulation section  464 , and buffer  466 . A receive section  458  can receive signals over various bands, including sub-bands of a larger bandwidth channel. A receive section  458  can include narrow band detect portion  462 , which can detect a narrow band preamble on a sub-band that can indicate a narrow band packet. A demodulation section  464  can demodulate received values to arrive and narrow band packet data, which can be stored in buffer  466 . It is understood that a demodulation path  460  could also include a frequency division counterpart to that shown in  FIG. 4A , as well (e.g., OFDMA demodulator). 
     In some embodiments, modulation/demodulation circuits, like those of  FIGS. 4A and 4B , can use a same modulation for both full channel and narrow band packet transmissions. In particular, DSSS modulation can be used for both channel and narrow band transmissions. 
       FIG. 4C  is a block schematic diagram of a transmission circuit  468  that can be included in embodiments. A transmission circuit  468  can enable the boosting of a narrow band packet portion of a transmission, to thereby increase the range of the narrow band packet. A transmission circuit  468  can include radio circuits  470 , a switch section  472 , a first (PA)  474 - 0  and a second PA  474 - 1 . Radio circuit  470  can generate the analog signals for a transmission. A transmission can include a first part (e.g., full channel preamble) followed by a second part (e.g., narrow band packet). Such a transmission can take the form of any of those shown in  FIG. 1B  and/or  FIG. 2A , or equivalents. 
     Switch section  472  can switch a signal from radio circuits  470  to either first PA  474 - 0  or second PA  474 - 1 , according to signal NB_BOOST. First PA  474 - 0  can be designed or configured to transmit over a full channel according to a predetermined PSD. In some embodiments, such a predetermined PSD can include a power limit restriction. PA  474 - 1  can be designed or configured to transmit over a sub-band according to another predetermined PSD that is greater than that of full channel transmissions provided by the other PA  474 - 0 . 
     Accordingly, after a full channel preamble is transmitted via first PA  474 - 0 , a transmission circuit  468  can switch to second PA  474 - 1 , thereby boosting the power of the narrow band packet. 
       FIG. 5  is a flow diagram of method  580  according to an embodiment. A method  580  can be executed by a device, such as an AP or the like, such as that shown as  102  in  FIGS. 1A to 1E . A method  580  can include generating NB packet data  580 - 0 . Such an action can include generating data to populate fields of a narrow band packet. In some embodiments, this can include generating data for one or more preamble fields that will result in a desired preamble when the packet is transmitted over a sub-band. 
     A method  580  can include assigning a sub-band to the narrow band packet  580 - 1 . Such an action can include assigning a narrow band packet  580 - 1  to one of multiple sub-bands over which data can be transmitted in parallel. 
     A method  580  can determine if data is to be transmitted on any other sub-band ( 580 - 2 ) (i.e., sub-bands not assigned to a narrow band packet). If data is to be transmitted in another sub-band (Y from  580 - 2 ), such a sub-band can be assigned to the data  580 - 3 . 
     A method  580  can then transmit a full channel preamble  580 - 4 . A full channel preamble can be a preamble transmitted over a bandwidth that is greater than and/or can include all the sub-bands. 
     A method  580  can then transmit on the sub-bands in parallel  580 - 5 , including a narrow band packet with a narrow band preamble  580 - 6 . Such an action can include transmitting data in their assigned sub-bands as well the narrow band packet in its assigned sub-band. 
     It is understood that a method  580  can include transmitting more than one narrow band packet in different sub-bands in parallel with one another, with each narrow band packet having a narrow band preamble. 
       FIG. 6  is a flow diagram of method  682  according to another embodiment. A method  682  can be executed by an AP or the like (e.g.,  102  in  FIGS. 1A to 1E ). A method  682  can include transmitting a narrow band packet on a sub-band (SUB-BANDx) in series with a full channel preamble  682 - 0 . Such an action can include transmitting a full channel preamble across a first bandwidth followed by a narrow band packet across a second bandwidth, where the second bandwidth is only a portion of the first bandwidth. 
     A method  682  can monitor the sub-band on which the narrow band packet was transmitted  682 - 1 . Such an action can include monitoring the sub-band for a particular type of response. In some embodiments, this can include monitoring the sub-band for a narrow band preamble. 
     If a narrow band response is detected (Y from  682 - 2 ), a method  682  can reserve a sub-band for narrow band packets  682 - 3 . Such an action can include reserving the sub-band on which the narrow band packet was transmitted (SUB-BANDx), reserving a sub-band indicated by data in the received response, and/or reserving a sub-band according to predetermined instructions. In particular embodiments this can include assigning a narrow band packet to a RU of a device operating according to the IEEE 802.11ax specification, or an equivalent. 
     If a narrow band response is not detected (N from  682 - 2 ), a method  682  can indicate that the sub-band is available for a data stream  682 - 4 . In some embodiments, this can include indicating a RU corresponding to the sub-band is available in an IEEE 802.11ax system. 
     While embodiments can include systems with various interconnected components, embodiments can also include unitary devices which can issue transmissions with a full channel preamble followed by a narrow band packet in a sub-band with its own preamble, as described herein or equivalents. In some embodiments, such unitary devices can be advantageously compact single integrated circuits (i.e., chips).  FIG. 7  shows one particular example of a packaged single chip device  702 . However, it is understood that a device according to embodiments can include any other suitable integrated circuit packaging type, as well as direct bonding of a combination device chip onto a circuit board or substrate. 
     Referring to  FIG. 8 , another system according to an embodiment is shown in a diagram. A system can include a router device  800 . Router device  800  can provide routing functions for a first protocol (e.g., WLAN) while also enabling a second, extended range protocol, which can utilize narrow band packets transmitted in a sub-band. In some embodiments, router device  800  can include a device  802  like that shown in  FIG. 7 . 
       FIG. 9  shows a system  900  according to another embodiment. A system  900  can include various local devices  904 - 0  to - 3  and a gateway device  902 . Local devices ( 904 - 0  to - 3 ) can include various Internet-of-thing (loT) type devices, which can operate as station devices. In the embodiment shown, local devices can be home automation devices, including lighting devices  904 - 0 , locking devices  904 - 1 , entertainment devices  904 - 2  and security devices  904 - 3 , as but a few of many possible examples. 
     A gateway device  902  can communicate with local devices  904 - 0  to - 3  according to a frequency multiplexing protocol, such as the IEEE 802.11ax standard or equivalent. However, gateway device  902  can further transmit a narrow band packet in a sub-band to extend an overall range of the system  900 , as described herein, or equivalents. Thus, any or all local devices  904 - 0  to - 3  can be located at a further range than conventional systems. 
     Enabling the transmissions of narrow band packets within a sub-band of a frequency multiplexing system can provide advantages over conventional networks, such as increased range to station devices. As but one example, in an IEEE 802.11ax environment, the signal-to-noise ration can be improved by about 6 dB when using a RU26 compared to a RU106 which results in tens of meters range extension depending on the environment. 
     While embodiments can execute channel communications according to any suitable protocol, in some embodiments such communications can be according to any suitable IEEE wireless standard, including but not limited to 802.11(a), 802.11(b), 802.11(g), 802.11(h), 802.11(ac) and/or 802.11 (ax). Further, embodiments can transmit across channels of any suitable wireless communication band, including but not limited to a 2.4 GHz band, 5.0 GHz band and/or 6.0 GHz band. Channels can have any suitable bandwidth size, including about 5 MHz, 10 MHz, 20 MHz, 40 MHz, 80 MHz and 160 MHz, with narrow bands having a smaller bandwidth than their corresponding channel(s). 
     It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, it is emphasized and should be appreciated that two or more references to “an embodiment” or “one embodiment” or “an alternative embodiment” in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the invention. 
     Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Rather, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.