Patent Publication Number: US-11382101-B1

Title: Bandwidth indication, negotiation and TXOP protection with multiple channel segments

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/823,504, entitled “Basic Service Set (BSS) with Multiple Channel Segments or &gt;160 MHz BW: —BW Indication, Negotiation and TXOP Protection,” filed on Mar. 25, 2019, U.S. Provisional Patent Application No. 62/831,596, entitled “Basic Service Set (BSS) with Multiple Channel Segments or &gt;160 MHz BW: —BW Indication, Negotiation and TXOP Protection,” filed on Apr. 9, 2019, U.S. Provisional Patent Application No. 62/870,437, entitled “Basic Service Set (BSS) with Multiple Channel Segments or &gt;160 MHz BW: —BW Indication, Negotiation and TXOP Protection,” filed on Jul. 3, 2019. All of the applications referenced above are incorporated herein by reference in their entireties. 
    
    
     FIELD OF TECHNOLOGY 
     The present disclosure relates generally to wireless communication systems, and more particularly to indicating a channel bandwidth, negotiating a channel bandwidth, and protecting a transmit opportunity period (TXOP) for wide bandwidth channels or channels having different frequency segments. 
     BACKGROUND 
     Wireless local area networks (WLANs) have evolved rapidly over the past two decades, and development of WLAN standards such as the Institute for Electrical and Electronics Engineers (IEEE) 802.11 Standard family has improved single-user peak data rates. One way in which data rates have been increased is by increasing the frequency bandwidth of communication channels used in WLANs. For example, the IEEE 802.11n Standard permits aggregation of two 20 MHz sub-channels to form a 40 MHz aggregate communication channel, whereas the more recent IEEE 802.11ax Standard permits aggregation of up to eight 20 MHz sub-channels to form up to 160 MHz aggregate communication channels. Work has now begun on a new iteration of the IEEE 802.11 Standard, which is referred to as the IEEE 802.11be Standard, or Extremely High Throughput (EHT) WLAN. The IEEE 802.11be Standard may permit aggregation of as many as sixteen 20 MHz sub-channels (or perhaps even more) to form up to 320 MHz aggregate communication channels (or perhaps even wider aggregate communication channels). Additionally, the IEEE 802.11be Standard may permit aggregation 20 MHz sub-channels in different frequency segments (for example, separated by a gap in frequency) to form a single aggregate channel. Further, the IEEE 802.11be Standard may permit aggregation 20 MHz sub-channels in different radio frequency (RF) bands to form a single aggregate channel. 
     The current draft of the IEEE 802.11ax Standard (referred to herein as “the IEEE 802.11ax Standard” for simplicity) provides mechanisms for indicating a bandwidth of a transmission within a single RF band, negotiating a channel bandwidth in a single RF band, and protecting a transmit opportunity period (TXOP) for a channel in a single RF band, the channel having a bandwidth up to 160 MHz. 
     SUMMARY 
     In an embodiment, a method for simultaneously transmitting in multiple frequency segments in a wireless local area network (WLAN) includes: generating, at a communication device, a first packet to include a first indication of one or more first frequency subchannels in a first frequency segment that will be utilized to transmit the first packet; generating, at the communication device, a second packet to include a second indication of one or more second frequency subchannels in a second frequency segment that will be utilized to transmit the second packet; and simultaneously transmitting, by the communication device, the first packet via the first frequency segment and the second packet via the second frequency segment. 
     In another embodiment, a communication device comprises: a wireless network interface device having one or more integrated circuit (IC) devices. The one or more IC devices are configured to: generate a first packet to include a first indication of one or more first frequency subchannels in a first frequency segment that will be utilized to transmit the first packet; generate a second packet to include a second indication of one or more second frequency subchannels in a second frequency segment that will be utilized to transmit the second packet; and control the wireless network interface device to simultaneously transmit the first packet via the first frequency segment and the second packet via the second frequency segment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an example communication system in which communication devices wirelessly exchange information via communication channels having bandwidths greater than 160 MHz and/or including multiple frequency segments, according to an embodiment. 
         FIG. 2A  is a diagram of an example communication channel having bandwidth greater than 160 MHz and including multiple frequency segments, according to an embodiment. 
         FIG. 2B  is a diagram of another example communication channel having bandwidth greater than 160 MHz and including multiple frequency segments, according to another embodiment. 
         FIG. 2C  is a diagram of yet another example communication channel having bandwidth greater than 160 MHz and including multiple frequency segments, according to another embodiment. 
         FIG. 3A  is a diagram of an example transmission in a communication channel such as shown in  FIGS. 2A-C , according to an embodiment. 
         FIG. 3B  is a diagram of another example transmission in a communication channel such as shown in  FIGS. 2A-C , according to another embodiment. 
         FIG. 4  is a diagram of yet another example transmission in a communication channel such as shown in  FIGS. 2A-C , according to another embodiment. 
         FIGS. 5A-B  are diagrams of example media access control (MAC) layer data units transmitted in a communication channel such as shown in  FIGS. 2A-C , according to an embodiment. 
         FIG. 6  is a diagram of an example request-to-send (RTS)/clear-to-send (CTS) exchange for negotiating a communication channel such as shown in  FIGS. 2A-C , according to an embodiment. 
         FIG. 7  is a diagram of another example RTS/CTS exchange for negotiating a communication channel such as shown in  FIGS. 2A-C , according to another embodiment. 
         FIG. 8  is a diagram of another example frame exchange for negotiating a communication channel such as shown in  FIGS. 2A-C , according to another embodiment. 
         FIG. 9  is a flow diagram of an example method for communicating information regarding a communication channel such as shown in  FIGS. 2A-C , according to an embodiment. 
         FIG. 10A  is a diagram of an example signal field of a physical layer (PHY) header of a packet, according to an embodiment. 
         FIG. 10B  is a diagram of an example service field of a packet, according to an embodiment. 
         FIG. 10C  is a diagram of an example media access control (MAC) layer header of a packet, according to an embodiment. 
         FIG. 10D  is a diagram of an example MAC layer data portion of a packet, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A next generation wireless local area network (WLAN) protocol (e.g., the IEEE 802.11be Standard, sometimes referred to as the Extremely High Throughput (EHT) WLAN Standard) may permit aggregation of as many as sixteen 20 MHz sub-channels (or perhaps even more) to form 320 MHz aggregate communication channels (or perhaps even wider aggregate communication channels). Additionally, the IEEE 802.11be Standard may permit aggregation 20 MHz sub-channels in different frequency segments (for example, separated by a gap in frequency) to form a single aggregate channel. Further, the IEEE 802.11be Standard may permit aggregation 20 MHz sub-channels in different radio frequency (RF) bands to form a single aggregate channel. 
     Described herein are various embodiments of techniques for indicating within a transmission a communication channel via which the transmission is being transmitted, negotiating a communication channel, and/or the protecting a transmit opportunity period (TXOP) for a communication channel, for wide bandwidth channels and/or channels having different frequency segments in a same or different RF bands. For example, in some embodiments, one or more first media access control (MAC) layer data units are transmitted in a first frequency segment, and one or more second MAC layer data units are simultaneously transmitted in a second frequency segment. The one or more first MAC layer data units include a first indication of one or more first frequency sub-channels in the first frequency segment that are utilized to transmit the one or more first MAC layer data units, and the one or more second MAC layer data units include a second indication of one or more second frequency sub-channels in the second frequency segment that are used to transmit the one or more second MAC layer data units, according to some embodiments. In various embodiments, the one or more first MAC layer data units are request-to-send (RTS) frames or clear-to-send (CTS) frames that are transmitted as part of a RTS/CTS negotiation of a communication channel and/or to protect a TXOP for a communication channel. 
       FIG. 1  is a diagram of an example WLAN 110 that uses communication channels wider than 160 MHz and/or communication channels in multiple frequency segments or in different radio frequency (RF) bands, according to an embodiment. The WLAN 110 includes an access point (AP)  114  that comprises a host processor  118  coupled to a wireless network interface device  122 . The wireless network interface device  122  includes one or more medium access control (MAC) processors  126  (sometimes referred to herein as “the MAC processor  126 ” for brevity) and one or more PHY processors  130  (sometimes referred to herein as “the PHY processor  130 ” for brevity). The PHY processor  130  includes a plurality of transceivers  134 , and the transceivers  134  are coupled to a plurality of antennas  138 . Although three transceivers  134  and three antennas  138  are illustrated in  FIG. 1 , the AP  114  includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers  134  and antennas  138  in other embodiments. In some embodiments, the AP  114  includes a higher number of antennas  138  than transceivers  134 , and antenna switching techniques are utilized. 
     In an embodiment, the wireless network interface device  122  is configured for operation within a single RF band at a given time. In an embodiment, the wireless network interface device  122  is configured to transmit and receive via a communication channel that spans a bandwidth greater than 160 MHz, the communication channel within a single RF band. In another embodiment, the wireless network interface device  122  is additionally configured for operation within two or more RF bands at the same time or at different times. For example, in an embodiment, the wireless network interface device  122  includes multiple PHY processors  130 , where respective PHY processors  130  correspond to respective RF bands. In another embodiment, the wireless network interface device  122  includes a single PHY processor  130 , where each transceiver  134  includes respective RF radios corresponding to respective RF bands. In an embodiment, the wireless network interface device  122  is configured to transmit and receive via a communication channel that spans a bandwidth greater than 160 MHz, the communication channel spanning multiple RF bands. 
     The wireless network interface device  122  is implemented using one or more integrated circuits (ICs) configured to operate as discussed below. For example, the MAC processor  126  may be implemented, at least partially, on a first IC, and the PHY processor  130  may be implemented, at least partially, on a second IC. The first IC and the second IC may be packaged together in a single IC package thereby forming a modular device, or the first IC and the second IC may be coupled together on a single printed board, for example, in various embodiments. As another example, at least a portion of the MAC processor  126  and at least a portion of the PHY processor  130  may be implemented on a single IC. For instance, the wireless network interface device  122  may be implemented using a system on a chip (SoC), where the SoC includes at least a portion of the MAC processor  126  and at least a portion of the PHY processor  130 . 
     In an embodiment, the host processor  118  includes a processor configured to execute machine readable instructions stored in a memory device (not shown) such as a random access memory (RAM), a read-only memory (ROM), a flash memory, etc. In an embodiment, the host processor  118  may be implemented, at least partially, on a first IC, and the network device  122  may be implemented, at least partially, on a second IC. As another example, the host processor  118  and at least a portion of the wireless network interface device  122  may be implemented on a single IC. 
     In various embodiments, the MAC processor  126  and/or the PHY processor  130  of the AP  114  are configured to generate data units, and process received data units, that conform to a WLAN communication protocol such as a communication protocol conforming to the IEEE 802.11 Standard or another suitable wireless communication protocol. For example, the MAC processor  126  may be configured to implement MAC layer functions, including MAC layer functions of the WLAN communication protocol, and the PHY processor  130  may be configured to implement PHY functions, including PHY functions of the WLAN communication protocol. For instance, the MAC processor  126  may be configured to generate MAC layer data units such as MAC service data units (MSDUs), MAC protocol data units (MPDUs), etc., and provide the MAC layer data units to the PHY processor  130 . The PHY processor  130  may be configured to receive MAC layer data units from the MAC processor  126  and to encapsulate the MAC layer data units to generate PHY data units such as PHY protocol data units (PPDUs) for transmission via the antennas  138 . Similarly, the PHY processor  130  may be configured to receive PHY data units that were received via the antennas  138 , and to extract MAC layer data units encapsulated within the PHY data units. The PHY processor  130  may provide the extracted MAC layer data units to the MAC processor  126 , which processes the MAC layer data units. 
     PHY data units are sometimes referred to herein as “packets”, and MAC layer data units are sometimes referred to herein as “frames”. 
     In connection with generating one or more RF signals for transmission, the PHY processor  130  is configured to process (which may include modulation, filtering, etc.) data corresponding to a PPDU to generate one or more digital baseband signals, and convert the digital baseband signal(s) to one or more analog baseband signals, according to an embodiment. Additionally, the PHY processor  130  is configured to upconvert the one or more analog baseband signals to one or more RF signals for transmission via the one or more antennas  138 . 
     In connection with receiving one or more RF signals, the PHY processor  130  is configured to downconvert the one or more RF signals to one or more analog baseband signals, and to convert the one or more analog baseband signals to one or more digital baseband signals. The PHY processor  130  is further configured to process (which may include demodulation, filtering, etc.) the one or more digital baseband signals to generate a PPDU. 
     The PHY processor  130  includes amplifiers (e.g., a low noise amplifier (LNA), a power amplifier, etc.), an RF downconverter, an RF upconverter, a plurality of filters, one or more analog-to-digital converters (ADCs), one or more digital-to-analog converters (DACs), one or more discrete Fourier transform (DFT) calculators (e.g., a fast Fourier transform (FFT) calculator), one or more inverse discrete Fourier transform (IDFT) calculators (e.g., an inverse fast Fourier transform (IFFT) calculator), one or more modulators, one or more demodulators, etc., in various embodiments. 
     The PHY processor  130  is configured to generate one or more RF signals that are provided to the one or more antennas  138 . The PHY processor  130  is also configured to receive one or more RF signals from the one or more antennas  138 . 
     The MAC processor  126  is configured to control the PHY processor  130  to generate one or more RF signals, for example, by providing one or more MAC layer data units (e.g., MPDUs) to the PHY processor  130 , and optionally providing one or more control signals to the PHY processor  130 , according to some embodiments. In an embodiment, the MAC processor  126  includes a processor configured to execute machine readable instructions stored in a memory device (not shown) such as a RAM, a read ROM, a flash memory, etc. In other embodiments, the MAC processor  126  additionally or alternatively includes one or more hardware state machines. 
     The MAC processor  126  includes, or implements, a control frame generator  142  that is configured to generate a control frame for negotiating a communication channel with a client station  154  and/or for protecting a TXOP for the communication channel, according to an embodiment. In some embodiments, the control frame is a request-to-send (RTS) frame. In other embodiments, the control frame is a clear-to-send (CTS) frame. In other embodiments, the control frame is another suitable control frame. For communication channels that are greater than 160 MHz and/or that are in multiple frequency segments and/or in multiple RF bands, the control frame generator  142  is configured to generate a first control frame to indicate a first portion of communication channel, such as a portion of the communication channel that is at most 160 MHz and/or within a first frequency segment and/or within a first RF band, wherein the first control frame is to be transmitted within the first portion of the communication channel; and the control frame generator  142  is configured to generate a second control frame to indicate a second portion of communication channel, such as a portion of the communication within a second frequency segment and/or within a second RF band, wherein the second control frame is to be transmitted within the second portion of the communication channel, according to an embodiment. In another embodiment, for communication channels that are greater than 160 MHz and/or that are in multiple frequency segments and/or in multiple RF bands, the control frame generator  142  is configured to generate a control frame to indicate the entire communication channel, wherein the control frame is to be transmitted within the entire communication channel according to an embodiment. 
     In an embodiment, the control frame generator  142  is implemented by a processor executing machine readable instructions stored in a memory, where the machine readable instructions cause the processor to perform acts described in more detail below. In another embodiment, the control frame generator  142  additionally or alternatively comprises hardware circuitry that is configured to perform acts described in more detail below. In some embodiments, the hardware circuitry comprises one or more hardware state machines that are configured to perform acts described in more detail below. 
     The PHY processor  130  includes, or implements, a signal field generator  146  that is configured to generate a signal field of a PHY header of a packet, according to some embodiments. For communication channels that are greater than 160 MHz and/or that are in multiple frequency segments and/or in multiple RF bands, the signal field generator  146  is configured to generate a first signal field to indicate a first portion of a communication channel, such as a portion of the communication channel that is at most 160 MHz and/or within a first frequency segment and/or within a first RF band, wherein the first signal field is to be transmitted within the first portion of the communication channel; and the signal field generator  146  is configured to generate a second signal field to indicate a second portion of communication channel, such as a portion of the communication within a second frequency segment and/or within a second RF band, wherein the second signal field is to be transmitted within the second portion of the communication channel, according to an embodiment. In another embodiment, for communication channels that are greater than 160 MHz and/or that are in multiple frequency segments and/or in multiple RF bands, the signal field generator  146  is configured to generate a signal field to indicate the entire communication channel, wherein the signal field is to be transmitted within the entire communication channel. 
     In some embodiments, when a communication channel that is at most 160 MHz and within one frequency segment (or within one RF band), the signal field generator  146  is configured to generate a signal field that indicates a bandwidth of the communication channel, wherein the signal field is to be transmitted within the entire communication channel. 
     In an embodiment, the signal field generator  146  comprises hardware circuitry that is configured to perform acts described in more detail below. In some embodiments, the hardware circuitry comprises one or more hardware state machines that are configured to perform acts described in more detail below. 
     In other embodiments, the control frame generator  142  and/or the signal field generator  146  are omitted. 
     The WLAN 110 also includes a plurality of client stations  154 . Although three client stations  154  are illustrated in  FIG. 1 , the WLAN 110 includes other suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations  154  in various embodiments. The client station  154 - 1  includes a host processor  158  coupled to a wireless network interface device  162 . The wireless network interface device  162  includes one or more MAC processors  166  (sometimes referred to herein as “the MAC processor  166 ” for brevity) and one or more PHY processors  170  (sometimes referred to herein as “the PHY processor  170 ” for brevity). The PHY processor  170  includes a plurality of transceivers  174 , and the transceivers  174  are coupled to a plurality of antennas  178 . Although three transceivers  174  and three antennas  178  are illustrated in  FIG. 1 , the client station  154 - 1  includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers  174  and antennas  178  in other embodiments. In some embodiments, the client station  154 - 1  includes a higher number of antennas  178  than transceivers  174 , and antenna switching techniques are utilized. 
     In an embodiment, the wireless network interface device  162  is configured for operation within a single RF band at a given time. In another embodiment, the wireless network interface device  162  is configured for operation within two or more RF bands at the same time or at different times. For example, in an embodiment, the wireless network interface device  162  includes multiple PHY processors  170 , where respective PHY processors  170  correspond to respective RF bands. In another embodiment, the wireless network interface device  162  includes a single PHY processor  170 , where each transceiver  174  includes respective RF radios corresponding to respective RF bands. In an embodiment, the wireless network interface device  162  includes multiple MAC processors  166 , where respective MAC processors  166  correspond to respective RF bands. In another embodiment, the wireless network interface device  162  includes a single MAC processor  166  corresponding to the multiple RF bands. 
     The wireless network interface device  162  is implemented using one or more ICs configured to operate as discussed below. For example, the MAC processor  166  may be implemented on at least a first IC, and the PHY processor  170  may be implemented on at least a second IC. The first IC and the second IC may be packaged together in a single IC package thereby forming a modular device, or the first IC and the second IC may be coupled together on a single printed board, for example, in various embodiments. As another example, at least a portion of the MAC processor  166  and at least a portion of the PHY processor  170  may be implemented on a single IC. For instance, the wireless network interface device  162  may be implemented using an SoC, where the SoC includes at least a portion of the MAC processor  166  and at least a portion of the PHY processor  170 . 
     In an embodiment, the host processor  158  includes a processor configured to execute machine readable instructions stored in a memory device (not shown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, the host processor  158  may be implemented, at least partially, on a first IC, and the network device  162  may be implemented, at least partially, on a second IC. As another example, the host processor  158  and at least a portion of the wireless network interface device  162  may be implemented on a single IC. 
     In various embodiments, the MAC processor  166  and the PHY processor  170  of the client station  154 - 1  are configured to generate data units, and process received data units, that conform to the WLAN communication protocol or another suitable communication protocol. For example, the MAC processor  166  may be configured to implement MAC layer functions, including MAC layer functions of the WLAN communication protocol, and the PHY processor  170  may be configured to implement PHY functions, including PHY functions of the WLAN communication protocol. The MAC processor  166  may be configured to generate MAC layer data units such as MSDUs, MPDUs, etc., and provide the MAC layer data units to the PHY processor  170 . The PHY processor  170  may be configured to receive MAC layer data units from the MAC processor  166  and encapsulate the MAC layer data units to generate PHY data units such as PPDUs for transmission via the antennas  178 . Similarly, the PHY processor  170  may be configured to receive PHY data units that were received via the antennas  178 , and extract MAC layer data units encapsulated within the PHY data units. The PHY processor  170  may provide the extracted MAC layer data units to the MAC processor  166 , which processes the MAC layer data units. 
     The PHY processor  170  is configured to downconvert one or more RF signals received via the one or more antennas  178  to one or more baseband analog signals, and convert the analog baseband signal(s) to one or more digital baseband signals, according to an embodiment. The PHY processor  170  is further configured to process the one or more digital baseband signals to demodulate the one or more digital baseband signals and to generate a PPDU. The PHY processor  170  includes amplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter, an RF upconverter, a plurality of filters, one or more ADCs, one or more DACs, one or more DFT calculators (e.g., an FFT calculator), one or more IDFT calculators (e.g., an IFFT calculator), one or more modulators, one or more demodulators, etc. 
     The PHY processor  170  is configured to generate one or more RF signals that are provided to the one or more antennas  178 . The PHY processor  170  is also configured to receive one or more RF signals from the one or more antennas  178 . 
     The MAC processor  166  is configured to control the PHY processor  170  to generate one or more RF signals by, for example, providing one or more MAC layer data units (e.g., MPDUs) to the PHY processor  170 , and optionally providing one or more control signals to the PHY processor  170 , according to some embodiments. In an embodiment, the MAC processor  166  includes a processor configured to execute machine readable instructions stored in a memory device (not shown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, the MAC processor  166  includes a hardware state machine. 
     In some embodiments, the MAC processor  166  implements a signal field generator (not shown) the same as or similar to the control frame generator  142  of the AP  114 . In other embodiments, the MAC processor  166  does not include such a control frame generator. In some embodiments, the PHY processor  170  implements a signal field generator (not shown) the same as or similar to the signal field generator  146  of the AP  114 . In other embodiments, the PHY processor  170  does not include such a signal field generator. 
     In an embodiment, each of the client stations  154 - 2  and  154 - 3  has a structure that is the same as or similar to the client station  154 - 1 . In an embodiment, one or more of the client stations  154 - 2  and  154 - 3  has a different suitable structure than the client station  154 - 1 . Each of the client stations  154 - 2  and  154 - 3  has the same or a different number of transceivers and antennas. For example, the client station  154 - 2  and/or the client station  154 - 3  each have only two transceivers and two antennas (not shown), according to an embodiment. 
       FIG. 2A  is a diagram of an example operating channel  200  that is used in the communication system  110  of  FIG. 1 , according to an embodiment. The operating channel  200  comprises a plurality of subchannels  204  in a first frequency segment  208  and a plurality of subchannels  212  in a second frequency segment  216 . The operating channel  200  spans an overall bandwidth  220 . The overall bandwidth  378  comprises two segments  382  separated by a gap in frequency  386 . In an embodiment, the first segment  208  and the second segment  216  are within a same radio frequency (RF) band. 
     In other embodiments, first segment  208  and the second segment  216  are in different RF bands. The Federal Communication Commission (FCC) now permits wireless local area networks (WLANs) to operate in multiple RF bands, e.g., the 2.4 GHz band (approximately 2.4 to 2.5 GHz), and the 5 GHz band (approximately 5.170 to 5.835 GHz). Recently, the FCC proposed that WLANs can also operate in the 6 GHz band (5.925 to 7.125 GHz). Regulatory agencies in other countries/regions also permit WLAN operation in the 2.4 GHz and 5 GHz bands, and are considering permitting WLAN operation the 6 GHz band. A future WLAN protocol, now under development, may permit multi-band operation in which a WLAN can use spectrum in multiple RF bands at the same time. For example, the future WLAN protocol may permit aggregation of spectrum in a first RF band with spectrum in a second RF band to form a composite communication channel that can be used to transmit packets that span the composite communication channel. 
     In one embodiment, each of the subchannels  204 / 212  spans 20 MHz. Thus, as illustrated in  FIG. 2A , the first segment  208  spans 160 MHz and the second segment  216  spans 80 MHz. In other embodiments, the second segment  216  includes another suitable number of subchannels  212  (e.g., one, two, four, eight, etc.) and spans another suitable bandwidth, such as 20 MHz, 40 MHz, 160 MHz, etc. 
     One subchannel  204 - 1  in the first segment  208  is designated as a primary subchannel and the other subchannels  204 / 212  are designated as secondary subchannels. Control and/or management frames are transmitted in the primary subchannel  204 - 1 , according to some embodiments. In some embodiments, the primary subchannel must be idle in order for any of the subchannels  204 / 212  to be used for a transmission, according to some embodiments. In some embodiments, a subchannel  212  in the second segment  216  is also designated as a primary subchannel (not shown). In other embodiments, no subchannel  212  in the second segment  216  is designated as a primary subchannel. 
       FIG. 2B  is a diagram of another example operating channel  250  that is used in the communication system  110  of  FIG. 1 , according to another embodiment. The operating channel  250  is similar to the example operating channel  200  of  FIG. 2A , and like-numbered elements are not described in detail for brevity. In the example operating channel  250  the first segment  208  and the second segment  216  are separated by a gap  254  in frequency. In some embodiments, the first segment  208  and the second segment  216  are in a same RF band. In other embodiments, the first segment  208  and the second segment  216  are in different RF bands. 
     In some embodiments, one or more of the subchannels  204 / 212  are “punctured”, e.g., nothing is transmitted within the “punctured” subchannels.  FIG. 2C  is a diagram of another example operating channel  270  that is used in the communication system  110  of  FIG. 1 , according to another embodiment. The operating channel  270  is similar to the example operating channel  200  of  FIG. 2A  and the example operating channel  250  of  FIG. 2B , and like-numbered elements are not described in detail for brevity. 
     In the example operating channel  270 , one of the subchannels (e.g., subchannel  204 - 7 ) is punctured. Although the example operating channel  270  is illustrated as having one punctured subchannel, other suitable operating channels include more than one punctured subchannel depending on the overall bandwidth and such that the aggregate bandwidth of the punctured operating channel is larger than an overall bandwidth of a next smaller sized operating channel that is permitted by the wireless communication protocol, according to various embodiments. In some embodiments, only secondary channels are permitted to be punctured. In other embodiments, primary channels are also permitted to be punctured. 
     Although the example operating channel  270  is illustrated as having a punctured subchannel in the first segment  208 , the operating channel  270  additionally or alternatively includes one or more punctured subchannels in the second segment  216 , in other embodiments. 
     In some embodiments, the first segment  208  and the second segment  216  are separated by a gap in frequency similar to the operating channel  250  of  FIG. 2B . 
     Although the example operating channels  200 ,  250 , and  270  of  FIGS. 2A-C  are illustrated as including two segments  208 / 216 , other suitable operating channels include three or more segments. In some embodiments, the one or more segments are separated from the second segment by a gap in frequency in which nothing is transmitted. 
     In some embodiments, respective frequency segments such as illustrated in  FIGS. 2A-C  are associated with different MAC addresses. For example, a communication device (such as the AP  114  and/or the client station  154 ) may include multiple RF radios with each RF radio associated with a different MAC address. In some embodiments, when an AP uses respective RF radios to receive in respective frequency segments, the respective frequency segments are associated with the respective MAC addresses of the respective RF radios of the AP  114 . 
       FIG. 3A  is a diagram of an example transmission  300  in a communication channel such as shown in  FIGS. 2A-C , or in another suitable communication channel. The transmission  300  comprises a single PPDU  304  transmitted via multiple frequency segments including a first segment  308  and a second segment  312 . A first portion  316  of the PPDU  304  is transmitted in the first segment  308 , and a second portion  320  of the PPDU  304  is transmitted in the second segment  312 . 
     In some embodiments, the first segment  308  is in a first RF band and the second segment  312  is in a second RF band. In other embodiments, the first segment  308  and the second segment  312  are in a same RF band. In some embodiments, the first segment  308  and the second segment  312  are separated by a gap in frequency. In other embodiments, the first segment  308  and the second segment  312  are adjacent in frequency, i.e., there is no gap in frequency between the first segment  308  and the second segment  312 . 
     The PPDU  304  comprises a PHY header  332  and a PHY data portion  336 . A first portion of the PHY header  332 - 1  is transmitted in the first frequency segment  308 , and a second portion of the PHY header  332 - 2  is transmitted in the second frequency segment  312 . Similarly, a first portion of the PHY data  336 - 1  is transmitted in the first frequency segment  308 , and a second portion of the PHY data  336 - 2  is transmitted in the second frequency segment  312 . The PHY header  332  and a PHY data portion  336  are transmitted simultaneously in the first segment  308  and the second segment  312 . 
     The PHY header comprises  332  a signal field  340  with a first portion  340 - 1  of the signal field in the first frequency segment  308  and a second portion  340 - 2  of the signal field in the second frequency segment  312 . In an embodiment, the first portion  340 - 1  of the signal field in the first frequency segment  308  includes different content than the second portion  340 - 2  of the signal field in the second frequency segment  312 . For example, in an embodiment, the first portion  340 - 1  of the signal field in the first frequency segment  308  includes an indicator of a bandwidth of the first segment  308 , and the second portion  340 - 2  of the signal field in the second frequency segment  312  includes an indicator of a bandwidth of the second segment  312 . In an embodiment, the first portion  340 - 1  of the signal field in the first frequency segment  308  does not include an indicator of the bandwidth of the second segment  312 , and the second portion  340 - 2  of the signal field in the second frequency segment  312  does not include an indicator of the bandwidth of the first segment  308 . In some embodiments, the first portion  340 - 1  of the signal field in the first frequency segment  308  and the second portion  340 - 2  of the signal field in the second frequency segment  312  both include an indicator of an overall bandwidth of a channel in which the PPDU  304  is transmitted, e.g., an aggregate bandwidth of the first segment  308  and the second segment  312 . In other embodiments, the first portion  340 - 1  of the signal field in the first frequency segment  308  and the second portion  340 - 2  of the signal field in the second frequency segment  312  do not include an indicator of the overall bandwidth of the channel in which the PPDU  304  is transmitted. 
     In some embodiments, one or more subchannels in the first segment  308  are punctured (not shown in  FIG. 3A ) and/or one or more subchannels in the second segment  312  are punctured (not shown in  FIG. 3A ). In some embodiments, the first portion  340 - 1  of the signal field in the first frequency segment  308  includes an indicator of punctured subchannel(s) (if any) in the first segment  308 , and the second portion  340 - 2  of the signal field in the second frequency segment  312  includes an indicator of punctured subchannel(s) (if any) in the second segment  312 . In an embodiment, the indicator of punctured subchannel(s) in the first segment  308  comprises a first bitmap in which respective bits of the first bitmap corresponds to respective subchannels in the first segment  308 , and where a first value of a bit indicates the subchannel is not punctured whereas a second value of the bit indicates the subchannel is punctured. Similarly, in an embodiment, the indicator of punctured subchannel(s) in the second segment  312  comprises a second bitmap in which respective bits of the second bitmap corresponds to respective subchannels in the second segment  312 , and where the first value of a bit indicates the subchannel is not punctured whereas the second value of the bit indicates the subchannel is punctured. In other embodiments, neither the first portion  340 - 1  of the signal field in the first frequency segment  308  nor the second portion  340 - 2  of the signal field in the second frequency segment  312  includes an indicator of punctured subchannel(s). 
     Although transmission of the PPDU  304  is illustrated in  FIG. 3A  as beginning at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission in the first segment  308  and transmission in the second segment  312  begin at different times. Similarly, although transmission of the PPDU  304  is illustrated in  FIG. 3A  as ending at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission in the first segment  308  and transmission in the second segment  312  end at different times. Similarly, although transmission of the PPDU  304  is illustrated in  FIG. 3A  as having a same duration in both the first segment  308  and the second segment  312 , in other embodiments, transmission in the first segment  308  has a different duration than a duration of transmission in the second segment  312 . 
       FIG. 3B  is a diagram of another example transmission  350  in a communication channel such as shown in  FIGS. 2A-C , or in another suitable communication channel. The transmission  350  is similar to the example transmission  300  of  FIG. 3A , but different PPDUs are transmitted in the first segment  308  and the second segment  312 . In particular, the transmission  350  comprises a first PPDU  354  transmitted in the first segment  308  and a second PPDU  358  transmitted in the second segment  312 . The first PPDU  354  is transmitted simultaneously with transmission of the second PPDU  358 . 
     The PPDU  354  comprises a PHY header  362  and a PHY data portion  366 . Similarly, the PPDU  358  comprises a PHY header  372  and a PHY data portion  376 . 
     The PHY header  362  comprises a signal field  384 , and the PHY header  372  includes a signal field  394 . In an embodiment, the signal field  384  in the first frequency segment  308  includes an indicator of a bandwidth of the first segment  308 , and the signal field  394  in the second frequency segment  312  includes an indicator of a bandwidth of the second segment  312 . In an embodiment, the signal field  384  in the first frequency segment  308  does not include an indicator of the bandwidth of the second segment  312 , and the signal field  394  in the second frequency segment  312  does not include an indicator of the bandwidth of the first segment  308 . In some embodiments, the signal field  384  in the first frequency segment  308  and the signal field  394  in the second frequency segment  312  both include an indicator of an overall bandwidth of a channel in which the PPDUs  354  and  358  are transmitted, e.g., an aggregate bandwidth of the first segment  308  and the second segment  312 . In other embodiments, the signal field  384  in the first frequency segment  308  and the signal field  394  in the second frequency segment  312  do not include an indicator of the overall bandwidth of the channel in which the PPDUs  354  and  358  are transmitted. 
     In some embodiments, one or more subchannels in the first segment  308  are punctured (not shown in  FIG. 3B ) and/or one or more subchannels in the second segment  312  are punctured (not shown in  FIG. 3B ). In some embodiments, the signal field  384  in the first frequency segment  308  includes an indicator of punctured subchannel(s) (if any) in the first segment  308 , and the signal field  394  in the second frequency segment  312  includes an indicator of punctured subchannel(s) (if any) in the second segment  312 . In an embodiment, the indicator of punctured subchannel(s) in the first segment  308  comprises a first bitmap in which respective bits of the first bitmap corresponds to respective subchannels in the first segment  308 , and where a first value of a bit indicates the subchannel is not punctured whereas a second value of the bit indicates the subchannel is punctured. Similarly, in an embodiment, the indicator of punctured subchannel(s) in the second segment  312  comprises a second bitmap in which respective bits of the second bitmap corresponds to respective subchannels in the second segment  312 , and where the first value of a bit indicates the subchannel is not punctured whereas the second value of the bit indicates the subchannel is punctured. In other embodiments, neither the first signal field  384  in the first frequency segment  308  nor the signal field  394  in the second frequency segment  312  includes an indicator of punctured subchannel(s). 
     Although transmission of the PPDUs  354  and  358  are illustrated in  FIG. 3B  as beginning at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission of the PPDU  354  in the first segment  308  and transmission of the PPDU  358  in the second segment  312  begin at different times. Similarly, although transmission of the PPDUs  354  and  358  are illustrated in  FIG. 3B  as ending at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission of the PPDU  354  in the first segment  308  and transmission of the PPDU  358  in the second segment  312  end at different times. Similarly, although transmission of the PPDU  354  is illustrated in  FIG. 3B  as having a same duration as transmission of the PPDU  358 , in other embodiments, transmission of the PPDU  354  in the first segment  308  has a different duration than a duration of transmission of the PPDU  358  in the second segment  312 . 
     Referring now to  FIGS. 3A-B , the signal fields  340 / 384 / 394  optionally include duration information indicating duration(s) of the PPDUs  304 / 354 / 358 , according to some embodiments, and a communication device that receives the any of the PPDUs  304 / 354 / 358  is configured to use duration information and bandwidth indication(s) in the signal fields  340 / 384 / 394  to determine a transmit opportunity period (TXOP) (or multiple TXOPs) corresponding to the transmissions  300 / 350  in the first segment  308  and the second segment  312 . If the transmissions  300 / 350  are not intended for the communication device, the communication device may refrain from attempting to use the first segment  308  or the second segment  312  during the TXOP, according to some embodiments. 
     In other embodiments, the communication device is configured to also use indication(s) of punctured subchannels in the signal fields  340 / 384 / 394  to determine the TXOP (or multiple TXOPs) corresponding to the transmissions  300 / 350  in the first segment  308  and the second segment  312 , taking into account the punctured subchannels (if any). If the transmissions  300 / 350  are not intended for the communication device, the communication device may refrain from attempting to use the first segment  308  (minus any punctured subchannels) or the second segment  312  (minus any punctured subchannels) during the TXOP, according to some embodiments. In some embodiments, the communication device may attempt to use one or more punctured subchannels in the first segment  308  or the second segment  312  during the TXOP. 
     Although indications of bandwidths of different frequency segments of a communication channel and indications of punctured subchannel(s) in the different frequency segments were described with reference to  FIGS. 3A-B  as being included in PHY headers of packets, in other embodiments, indications of bandwidths of different frequency segments of a communication channel and/or indications of punctured subchannel(s) in the different frequency segments are additionally or alternatively included in MAC data units. 
     In some embodiments, different segments of spectrum are associated with different spectrum segment identifiers (IDs). For example, different RF bands correspond with different respective spectrum segment IDs, according to an embodiment. In other embodiments, an RF band may be partitioned into a plurality of spectrum segments corresponding to different respective spectrum segment IDs. In other embodiments, a plurality of spectrum segments across a plurality of RF bands correspond to different respective spectrum segment IDs. Referring now to  FIG. 3A , in some embodiments, the first portion  340 - 1  of the signal field additionally includes a first spectrum segment ID corresponding to the segment  308 , and the second portion  340 - 2  of the signal field additionally includes a second spectrum segment ID corresponding to the segment  312 . In other embodiments, neither the first portion  340 - 1  of the signal field nor the second portion  340 - 2  of the signal field includes any spectrum segment IDs corresponding to the segment  308  or the segment  312 . In some embodiments, the first portion  340 - 1  of the signal field additionally includes a first MAC address corresponding to the segment  308 , and the second portion  340 - 2  of the signal field additionally includes a second MAC address corresponding to the segment  312 . In other embodiments, the first portion  340 - 1  of the signal field does not include the first MAC address corresponding to the segment  308 , and the second portion  340 - 2  of the signal field does not include the second MAC address corresponding to the segment  312 . 
     Referring now to  FIG. 3B , in some embodiments, the signal field  384  additionally includes a first spectrum segment ID corresponding to the segment  308 , and the signal field  394  additionally includes a second spectrum segment ID corresponding to the segment  312 . In other embodiments, neither the signal field  384  nor the signal field  394  includes any spectrum segment IDs corresponding to the segment  308  or the segment  312 . In some embodiments, the signal field  384  additionally includes a first MAC address corresponding to the segment  308 , and the signal field  394  additionally includes a second MAC address corresponding to the segment  312 . In other embodiments, the signal field  384  does not include the first MAC address corresponding to the segment  308 , and the signal field  394  does not include the second MAC address corresponding to the segment  312 . 
     Referring now to  FIGS. 3A-B , in some embodiments, rather than a signal field including the indication of the bandwidth of in the frequency segment, a service field in a PHY data portion (e.g., in the PHY data portion  336 - 1 / 336 - 2  or in the PHY data portion  376 / 366 ) includes the indication of the bandwidth. For example, a network interface device sets (e.g., the network interface device  122  sets, the MAC processor  126  sets, the control frame generator sets, etc.) a transmitter address field in a MAC header in the packet to a bandwidth signaling address, which indicates that the service field includes the indication of the bandwidth. 
     Similarly, in various embodiments, the service field additionally or alternatively includes one or both of: an indicator of punctured subchannel(s) in the frequency segment and a spectrum segment ID, such as discussed above. 
       FIG. 4  is a diagram of another example transmission  400  in a communication channel such as shown in  FIGS. 2A-C , or in another suitable communication channel. The transmission  400  comprises a first PPDU  404  transmitted in the first segment  308  and a second PPDU  408  transmitted in the second segment  312 . The first PPDU  404  is transmitted simultaneously with transmission of the second PPDU  408 . 
     The PPDU  404  comprises a PHY header  412  and a PHY data portion  416 . Similarly, the PPDU  408  comprises a PHY header  422  and a PHY data portion  426 . 
     The PHY data portion  416  comprises a service field  434 , and the PHY data portion  426  includes a service field  438 . In an embodiment, the service field  434  in the first frequency segment  308  includes an indicator of a bandwidth of the first segment  308 , and the service field  438  in the second frequency segment  312  includes an indicator of a bandwidth of the second segment  312 . In an embodiment, the service field  434  in the first frequency segment  308  does not include an indicator of the bandwidth of the second segment  312 , and the service field  438  in the second frequency segment  312  does not include an indicator of the bandwidth of the first segment  308 . In some embodiments, the service field  434  in the first frequency segment  308  and the service field  438  in the second frequency segment  312  both include an indicator of an overall bandwidth of a channel in which the PPDUs  404  and  408  are transmitted, e.g., an aggregate bandwidth of the first segment  308  and the second segment  312 . In other embodiments, the service field  434  in the first frequency segment  308  and the service field  438  in the second frequency segment  312  do not include an indicator of the overall bandwidth of the channel in which the PPDUs  404  and  408  are transmitted. 
     In some embodiments, one or more subchannels in the first segment  308  are punctured (not shown in  FIG. 4 ) and/or one or more subchannels in the second segment  312  are punctured (not shown in  FIG. 4 ). In some embodiments, the service field  434  in the first frequency segment  308  includes an indicator of punctured subchannel(s) (if any) in the first segment  308 , and the service field  438  in the second frequency segment  312  includes an indicator of punctured subchannel(s) (if any) in the second segment  312 . In an embodiment, the indicator of punctured subchannel(s) in the first segment  308  comprises a first bitmap in which respective bits of the first bitmap corresponds to respective subchannels in the first segment  308 , and where a first value of a bit indicates the subchannel is not punctured whereas a second value of the bit indicates the subchannel is punctured. Similarly, in an embodiment, the indicator of punctured subchannel(s) in the second segment  312  comprises a second bitmap in which respective bits of the second bitmap corresponds to respective subchannels in the second segment  312 , and where the first value of a bit indicates the subchannel is not punctured whereas the second value of the bit indicates the subchannel is punctured. In other embodiments, neither the service field  434  in the first frequency segment  308  nor the service field  438  in the second frequency segment  312  includes an indicator of punctured subchannel(s). 
     Although transmission of the PPDUs  404  and  408  are illustrated in  FIG. 4  as beginning at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission of the PPDU  404  in the first segment  308  and transmission of the PPDU  408  in the second segment  312  begin at different times. Similarly, although transmission of the PPDUs  404  and  408  are illustrated in  FIG. 4  as ending at a same time in both the first segment  308  and the second segment  312 , in other embodiments, transmission of the PPDU  404  in the first segment  308  and transmission of the PPDU  408  in the second segment  312  end at different times. Similarly, although transmission of the PPDU  404  is illustrated in  FIG. 4  as having a same duration as transmission of the PPDU  408 , in other embodiments, transmission of the PPDU  404  in the first segment  308  has a different duration than a duration of transmission of the PPDU  408  in the second segment  312 . 
     MAC headers (not shown) in the PHY data portions  416 / 426  include duration information indicating duration(s) of the PPDUs  404 / 408 , according to some embodiments, and a communication device that receives any of the PPDUs  404 / 408  is configured to use duration information and bandwidth indication(s) in the service fields  434 / 438  to determine a TXOP (or multiple TXOPs) corresponding to the transmissions PPDUs  404 / 408  in the first segment  308  and the second segment  312 . If the PPDUs  404 / 408  are not intended for the communication device, the communication device may refrain from attempting to use the first segment  308  or the second segment  312  during the TXOP, according to some embodiments. 
     In other embodiments, the communication device is configured to also use indication(s) of punctured subchannels in the service fields  434 / 438  to determine the TXOP (or multiple TXOPs) corresponding to the PPDUs  404 / 408  in the first segment  308  and the second segment  312 , taking into account the punctured subchannels (if any). If the PPDUs  404 / 408  are not intended for the communication device, the communication device may refrain from attempting to use the first segment  308  (minus any punctured subchannels) or the second segment  312  (minus any punctured subchannels) during the TXOP, according to some embodiments. In some embodiments, the communication device may attempt to use one or more punctured subchannels in the first segment  308  or the second segment  312  during the TXOP. 
     In some embodiments, the service field  434  additionally includes a first spectrum segment ID corresponding to the segment  308 , and the service field  438  additionally includes a second spectrum segment ID corresponding to the segment  312 . In other embodiments, neither the service field  434  nor the service field  438  includes any spectrum segment IDs corresponding to the segment  308  or the segment  312 . 
     In an embodiment, a network interface device sets (e.g., the network interface device  122  sets, the MAC processor  126  sets, the control frame generator sets, etc.) a transmitter address field in a MAC header in the PPDU  404  to a bandwidth signaling address, which indicates that the service field  434  includes the indication of the bandwidth, and sets a transmitter address field in a MAC header in the PPDU  408  to a bandwidth signaling address, which indicates that the service field  438  includes the indication of the bandwidth. 
       FIG. 5A  is a diagram of an example MAC data unit (e.g., an MPDU)  500  that is transmitted in a communication channel such as described with reference to  FIGS. 2A-C , or in another suitable communication channel that includes two or more frequency segments, according to an embodiment. The MAC data unit  500  is transmitted within one frequency segment of the communication channel, but is not transmitted within other frequency segment(s) of the communication channel, according to an embodiment. 
     In various embodiments, the MAC data unit  500  comprises a management frame, a control frame, a data frame, etc. In various illustrative embodiments, the MAC data unit  500  comprises a null data packet announcement (NDPA) frame, a request-to-send (RTS) frame, a clear-to-send (CTS) frame, a trigger frame (e.g., configured to prompt an uplink transmission), a quality of service (QoS) null frame, etc. 
     The MAC data unit  500  includes a MAC header  504  and a MAC data portion  508 . In some embodiments, the MAC data portion  508  is omitted. The MAC header  504  includes an indication of a bandwidth of a frequency segment of the communication channel in which the MAC data unit  500  is transmitted, according to an embodiment. The MAC header  504  does not include an indication(s) of a bandwidth(s) of any other frequency segment(s) of the communication channel, according to an embodiment. In some embodiments, the MAC header  504  does not include an indication of an overall bandwidth of the communication channel. In other embodiments, the MAC header  504  includes indication(s) of bandwidth(s) of other frequency segment(s) of the communication channel and/or an indication of an overall bandwidth of the communication channel. 
     In some embodiments, the MAC header  504  additionally includes an indicator of punctured subchannel(s) (if any) in the frequency segment in which the MAC data unit  500  is transmitted. In an embodiment, the indicator of punctured subchannel(s) comprises a bitmap in which respective bits of the bitmap corresponds to respective subchannels in the frequency segment in which the MAC data unit  500  is transmitted, where a first value of a bit indicates the subchannel is not punctured whereas a second value of the bit indicates the subchannel is punctured. 
     In some embodiments, the MAC header  504  additionally includes a spectrum segment ID corresponding to the frequency segment in which the MAC data unit  500  is transmitted. In other embodiments, MAC header  504  does not include a spectrum segment ID corresponding to the frequency segment in which the MAC data unit  500  is transmitted. 
       FIG. 5B  is a diagram of another example MAC data unit (e.g., an MPDU)  550  that is transmitted in a communication channel such as described with reference to  FIGS. 2A-C , or in another suitable communication channel that includes two or more frequency segments, according to an embodiment. The MAC data unit  550  is transmitted within one frequency segment of the communication channel, but is not transmitted within other frequency segment(s) of the communication channel, according to an embodiment. 
     In various embodiments, the MAC data unit  550  comprises a management frame, a control frame, a data frame, etc. In various illustrative embodiments, the MAC data unit  500  comprises a null data packet announcement (NDPA) frame, a request-to-send (RTS) frame, a clear-to-send (CTS) frame, a trigger frame (e.g., configured to prompt an uplink transmission), a quality of service (QoS) null frame, etc. 
     The MAC data unit  550  includes a MAC header  554  and a MAC data portion  558 . The MAC data portion  558  includes an indication of a bandwidth of a frequency segment of the communication channel in which the MAC data unit  550  is transmitted, according to an embodiment. The MAC data portion  558  does not include an indication(s) of a bandwidth(s) of any other frequency segment(s) of the communication channel, according to an embodiment. In some embodiments, the MAC data portion  558  does not include an indication of an overall bandwidth of the communication channel. In other embodiments, the MAC data portion  558  includes indication(s) of bandwidth(s) of other frequency segment(s) of the communication channel and/or an indication of an overall bandwidth of the communication channel. 
     In some embodiments, the MAC data portion  558  additionally includes an indicator of punctured subchannel(s) (if any) in the frequency segment in which the MAC data unit  500  is transmitted. In an embodiment, the indicator of punctured subchannel(s) comprises a bitmap in which respective bits of the bitmap corresponds to respective subchannels in the frequency segment in which the MAC data unit  500  is transmitted, where a first value of a bit indicates the subchannel is not punctured whereas a second value of the bit indicates the subchannel is punctured. 
     In some embodiments, the MAC data portion  558  additionally includes a spectrum segment ID corresponding to a segment of spectrum in which the MAC data unit  550  is transmitted. In other embodiments, MAC data portion  558  does not include a spectrum segment ID corresponding to the frequency segment in which the MAC data unit  500  is transmitted. In some embodiments, the MAC data portion  558  additionally includes a MAC address corresponding to the frequency segment in which the MAC data unit  550  is transmitted. In other embodiments, MAC data portion  558  does not include a MAC address corresponding to the frequency segment in which the MAC data unit  500  is transmitted. 
     In any of the examples described above with reference to  FIGS. 3A-5B , a signal field, a service field, a MAC header, a MAC data portion, etc., includes an indicator of punctured subchannels across the overall bandwidth of the communication channel, according to some embodiments. 
       FIG. 6  is a diagram of an example RTS/CTS exchange  600  for negotiating a communication channel to use for a TXOP, according to an embodiment. A first communication device transmits a plurality of RTS frames  608  in a plurality of subchannels of a communication channel to a second communication device. The communication channel includes the first frequency segment  208  and the second frequency segment  216  discussed above with reference to  FIGS. 2A-C , according to some embodiments. The communication channel includes a punctured subchannel  604 , and thus an RTS frame is not transmitted in the subchannel  604 . 
     The RTS frames  608  are transmitted in packets such as described with reference to  FIG. 3B or 4 , or in other suitable packets, according to various embodiments. In some embodiments, RTS frames  608  transmitted in the first segment  208  are transmitted in packets that include a service field with a bandwidth indicator indicating the first frequency segment  208 , and RTS frames  608  transmitted in the second segment  216  are transmitted in packets that include a service field with a bandwidth indicator indicating the second frequency segment  216 . In some embodiments, RTS frames  608  transmitted in the first segment  208  are transmitted in packets that include a signal field with a bandwidth indicator indicating the first frequency segment  208 , and RTS frames  608  transmitted in the second segment  216  are transmitted in packets that include a signal field with a bandwidth indicator indicating the second frequency segment  216 . 
     In some embodiments, the RTS frames  608  include an indicator of punctured subchannel(s) in the overall communication channel. For example, in some embodiments, all of the RTS frames  608  include a bitmap corresponding to the overall communication channel, the bitmap indicating the subchannel  604  is punctured. In other embodiments, RTS frames  608  transmitted in the first segment  208  include a bitmap corresponding to the first segment  208  that indicates the subchannel  604  is punctured, and RTS frames  608  transmitted in the second segment  216  include a bitmap corresponding to the second segment  216 . 
     In response to receiving the RTS frames  608 , the second communication device determines whether subchannels in which the second communication device received RTS frames  608  are idle. In the example of  FIG. 6 , the second communication device determines that all of the subchannels (which are not punctured) in the first segment  208  are idle, but determines that one of the subchannels in the second segment  216  in is not idle (i.e., is busy). Because all of the subchannels in the first segment  208  in which RTS frames  608  were received were idle, the second communication device transmits CTS frames  616  in all of the subchannels in the first segment  208  in which RTS frames  608  were received. On the other hand, because one of the subchannels in the second segment  216  was not idle, the second communication device determines a next smallest allowed aggregation of subchannels within the second segment  216  that does not use the busy subchannel, and transmits CTS frames within those subchannels. As a result, the second communication device transmits CTS frames in a third segment  632  that omits two subchannels from the second segment  216  even though only one subchannel was determined to be busy. 
     The subchannels in which CTS frames  616  are transmitted establish the subchannels to be used for the TXOP, according to an embodiment. In other embodiments in which the CTS frames  616  include indications of punctured channel(s), if any, the indications of punctured channel(s), if any, in the CTS frames  616  additionally or alternatively establish the subchannels to be used for the TXOP. 
     The CTS frames  616  are transmitted in packets such as described with reference to  FIG. 3B or 4 , or in other suitable packets such as packets that do not have signal fields and/or service fields with bandwidth indicators, according to various embodiments. In some embodiments, CTS frames  616  transmitted in the first segment  208  are transmitted in packets that include a service field with a bandwidth indicator indicating the first frequency segment  208 , and CTS frames  616  transmitted in the third segment  632  are transmitted in packets that include a service field with a bandwidth indicator indicating the second frequency segment  216 . In some embodiments, CTS frames  616  transmitted in the third segment  632  are transmitted in packets that include a service field with a bandwidth indicator indicating the third frequency segment  632 . 
     In some embodiments, CTS frames  616  transmitted in the first segment  208  are transmitted in packets that include a signal field with a bandwidth indicator indicating the first frequency segment  208 , and CTS frames  616  transmitted in the third segment  632  are transmitted in packets that include a signal field with a bandwidth indicator indicating the second frequency segment  216 . In some embodiments, CTS frames  616  transmitted in the third segment  632  are transmitted in packets that include a signal field with a bandwidth indicator indicating the third frequency segment  632 . 
     In some embodiments, the CTS frames  616  include an indicator of punctured subchannel(s) in the overall communication channel. For example, in some embodiments, all of the CTS frames  616  include a bitmap corresponding to the overall communication channel, the bitmap indicating the subchannel  604  is punctured. In other embodiments, CTS frames  616  transmitted in the first segment  208  include a bitmap corresponding to the first segment  208  that indicates the subchannel  604  is punctured, and CTS frames  616  transmitted in the third segment  632  include a bitmap corresponding to the second segment  216  (or the third segment). 
     In some embodiments, the CTS frames  616  do not include a bandwidth indicator such as described above and/or do not include an indicator of punctured subchannels as described above. 
       FIG. 7  is a diagram of another example RTS/CTS exchange  700  for negotiating a communication channel to use for a TXOP, according to another embodiment. The RTS/CTS exchange  700  is similar to the RTS/CTS exchange  600  of  FIG. 6 , and like numbered elements are not discussed in detail for brevity. 
     As in RTS/CTS exchange  600  of  FIG. 6 , the second communication device determines that one of the subchannels in the second segment  216  is not idle. Because the one subchannel in the second segment  216  is not idle, the second communication device transmits CTS frames  616  in the remaining subchannels of the second segment  216 . 
     The CTS frames  616  are transmitted in packets such as described with reference to  FIG. 3B or 4 , or in other suitable packets, according to various embodiments. Similar to the RTS/CTS exchange  600  of  FIG. 6 , CTS frames  616  transmitted in the first segment  208  are transmitted in packets that include a service field (or a signal field) with a bandwidth indicator indicating the first frequency segment  208 , and CTS frames  616  transmitted in the second segment  216  are transmitted in packets that include a service field (or a signal field) with a bandwidth indicator indicating the second frequency segment  216 . 
     In some embodiments, the CTS frames  616  include an indicator of punctured subchannel(s) in the overall communication channel. For example, in some embodiments, all of the CTS frames  616  include a bitmap corresponding to the overall communication channel, the bitmap indicating the subchannel  604  and the subchannel  704  are punctured. In other embodiments, CTS frames  608  transmitted in the first segment  208  include a bitmap corresponding to the first segment  208  that indicates the subchannel  604  is punctured, and CTS frames  616  transmitted in the second segment  216  include a bitmap corresponding to the second segment  216  that indicates the subchannel  704  is punctured. 
     In some embodiments, the CTS frames  616  do not include a bandwidth indicator such as described above and/or do not include an indicator of punctured subchannels as described above. 
     The subchannels in which CTS frames  616  are transmitted establish the subchannels to be used for the TXOP, according to an embodiment. In other embodiments in which the CTS frames  616  include indications of punctured channel(s), if any, the indications of punctured channel(s), if any, in the CTS frames  616  additionally or alternatively establish the subchannels to be used for the TXOP. 
     Referring now to  FIGS. 6 and 7 , in some embodiments, each of the RTS frames  608  and the CTS frames  616  are transmitted in a 20 MHz-wide legacy PPDU (sometimes referred to in the IEEE 802.11 Standard as a “non-HT PPDU”). Duplicates of a PPDU including RTS frames  608  (sometimes referred to in the IEEE 802.11 Standard as a “non-HT duplicate PPDU”) in the first segment  208  are transmitted in each 20 MHz subchannel (except in any punctured subchannels) of the first segment  208 . Similarly, RTS frames in non-HT duplicate PPDUs are transmitted in each 20 MHz subchannel (except in any punctured subchannels) of the second segment  216 . CTS frames  616  are similarly transmitted in non-HT duplicate PPDUs, according to some embodiments. 
     In other embodiments, each of the RTS frames  608  and the CTS frames  616  are transmitted in other suitable PPDUs, such as a non-legacy PPDU. 
       FIG. 8  is a diagram of an example exchange  800  for negotiating a communication channel to use for a TXOP, according to another embodiment. The exchange  800  is similar to the RTS/CTS exchange  700  of  FIG. 7 , and like numbered elements are not discussed in detail for brevity. 
     In other embodiments, each of the RTS frames  608  and the CTS frames  616  are transmitted in suitable PPDU, such as a non-legacy PPDU. 
     Instead of transmitting RTS frames  608 , the first communication devices transmits trigger frames  808 . The trigger frames  808  are configured to prompt the second communication device to transmit quality of service (QoS) Null frames  816 . Each QoS Null frame  816  includes a MAC header (e.g., the MAC header  504 , the MAC header  554 , or another suitable MAC header) but does not include a MAC data portion. 
     As in RTS/CTS exchanges  700  of  FIG. 7 , the second communication device determines that one of the subchannels in the second segment  216  is not idle. Because the one subchannel in the second segment  216  is not idle, the second communication device transmits QoS Null frames  816  in the remaining subchannels of the second segment  216 . 
     The trigger frames  808  are transmitted in packets such as described with reference to  FIG. 3B or 4 , or in other suitable packets, according to various embodiments. In some embodiments, trigger frames  808  transmitted in the first segment  208  are transmitted in packets that include a service field with a bandwidth indicator indicating the first frequency segment  208 , and trigger frames  808  transmitted in the second segment  216  are transmitted in packets that include a service field with a bandwidth indicator indicating the second frequency segment  216 . In some embodiments, trigger frames  808  transmitted in the first segment  208  are transmitted in packets that include a signal field with a bandwidth indicator indicating the first frequency segment  208 , and trigger frames  808  transmitted in the second segment  216  are transmitted in packets that include a signal field with a bandwidth indicator indicating the second frequency segment  216 . 
     In some embodiments, the trigger frames  808  include an indicator of punctured subchannel(s) in the overall communication channel. For example, in some embodiments, all of the trigger frames  808  include a bitmap corresponding to the overall communication channel, the bitmap indicating the subchannel  604  is punctured. In other embodiments, trigger frames  808  transmitted in the first segment  208  include a bitmap corresponding to the first segment  208  that indicates the subchannel  604  is punctured, and trigger frames  808  transmitted in the second segment  216  include a bitmap corresponding to the second segment  216 . 
     In response to receiving the trigger frames  808 , the second communication device determines whether subchannels in which the second communication device received trigger frames  808  are idle, and transits QoS Null frames  816  in any subchannels that are determined to be idle. 
     The QoS Null frames  816  are transmitted in packets such as described with reference to  FIG. 3B or 4 , or in other suitable packets, according to various embodiments. Similar to the RTS/CTS exchange  700  of  FIG. 7 , QoS Null frames  816  transmitted in the first segment  208  are transmitted in packets that include a service field (or a signal field) with a bandwidth indicator indicating the first frequency segment  208 , and QoS Null frames  816  transmitted in the second segment  216  are transmitted in packets that include a service field (or a signal field) with a bandwidth indicator indicating the second frequency segment  216 . 
     In some embodiments, the QoS Null frames  816  include an indicator of punctured subchannel(s) in the overall communication channel. For example, in some embodiments, all of the QoS Null frames  816  include a bitmap corresponding to the overall communication channel, the bitmap indicating the subchannel  604  and the subchannel  704  are punctured. In other embodiments, QoS Null frames  816  transmitted in the first segment  208  include a bitmap corresponding to the first segment  208  that indicates the subchannel  604  is punctured, and QoS Null frames  816  transmitted in the second segment  216  include a bitmap corresponding to the second segment  216  that indicates the subchannel  704  is punctured. 
     In some embodiments, the QoS Null frames  816  do not include a bandwidth indicator such as described above and/or do not include an indicator of punctured subchannels as described above. 
     The subchannels in which QoS Null frames  816  are transmitted establish the subchannels to be used for the TXOP, according to an embodiment. In other embodiments in which the QoS Null frames  816  include indications of punctured channel(s), if any, the indications of punctured channel(s), if any, in the QoS Null frames  816  additionally or alternatively establish the subchannels to be used for the TXOP. 
     In some embodiments, each of the trigger frames  808  and the QoS Null frames  816  are transmitted in a non-HT PPDU. Trigger frames  808  in the first segment  208  are included in non-HT duplicate PPDUs and transmitted in each 20 MHz subchannel (except in any punctured subchannels) of the first segment  208 . Similarly, trigger frames  808  in non-HT duplicate PPDUs are transmitted in each 20 MHz subchannel (except in any punctured subchannels) of the second segment  216 . QoS Null frames  816  are similarly transmitted in non-HT duplicate PPDUs, according to some embodiments. 
     In other embodiments, each of the trigger frames  808  and the QoS Null frames  816  are transmitted in other suitable PPDUs, such as a non-legacy PPDU. 
     In various embodiments, a bandwidth indicator for a frequency segment such as described above includes i) a width indicator that indicates width, in frequency, of the frequency segment, and ii) a starting subchannel indicator that indicates a lowest (in frequency) subchannel of the frequency segment. In various other embodiments, a bandwidth indicator for a frequency segment such as described above includes i) a width indicator that indicates width, in frequency, of the frequency segment, and ii) a center frequency indicator that indicates a center frequency of the frequency segment. 
     In some embodiments, an indicator of punctured channels (if any) for a communication channel such as described above includes an 16-bit bitmap, where each bit of the bitmap corresponds to a respective 20 MHz subchannel among a set of up to sixteen subchannels. In some embodiments, an indicator of punctured channels (if any) for a frequency segment such as described above includes an 8-bit bitmap, where each bit of the bitmap corresponds to a respective 20 MHz subchannel among a set of up to eight subchannels. In some embodiments, an indicator of punctured channels (if any) for a communication channel such as described above includes an 8-bit bitmap, where each bit of the bitmap corresponds to a respective 40 MHz subchannel (e.g., a respective pair of adjacent 20 MHz subchannels) among a set of up to eight 40 MHz subchannels. 
       FIG. 9  is a flow diagram of an example method  900  for communicating information regarding a communication channel that comprises multiple frequency segments, according to an embodiment. The method  900  is implemented by a wireless communication device such as any of the communication devices of  FIG. 1 , or another suitable wireless communication device. The method  900  is described with reference to  FIG. 1  for ease of explanation. In other embodiments, however, the method  900  is implemented by another suitable communication device having a suitable structure different than the communication devices of  FIG. 1 . 
     In various embodiments, the method  900  is performed in the context of the example communication channels described above with reference to  FIGS. 2A-C . In other embodiments, the method  900  is performed in the context of other suitable communication channels that comprise multiple frequency segments. 
     In various embodiments, the method  900  is performed in the context of packets described above with reference to  FIGS. 3B and 4 . In other embodiments, the method  900  is performed in the context of other suitable packets. 
     In various embodiments, the method  900  is performed in the context of MAC layer data units and/or frame exchanges described above with reference to  FIGS. 5A-B  and  6 - 8 . In other embodiments, the method  900  is performed in the context of other suitable MAC layer data units. 
     At block  904 , at a communication device generates (e.g., the network interface device  122  generates, the PHY processor  130  generates, etc.) a first packet to include a first indication of one or more first frequency subchannels in a first frequency segment that will be utilized to transmit the first packet. 
     At block  908 , the communication device generates (e.g., the network interface device  122  generates, the PHY processor  130  generates, etc.) a second packet to include a second indication of one or more second frequency subchannels in a second frequency segment that will be utilized to transmit the second packet. 
     In some embodiments, generating the first packet at block  904  comprises generating the first packet to include a first indication of the first frequency segment; and generating the second packet at block  908  comprises generating the second packet to include a second indication of the second frequency segment. 
     In some embodiments, generating the first packet at block  904  comprises generating the first packet to include a first service field that includes the first indication of the first frequency segment, the first service field within a first PHY data portion of the first packet; and generating the second packet at block  908  comprises generating the second packet to include a second service field that includes the second indication of the second frequency segment, the second service field within a second PHY data portion of the second packet. 
     In some embodiments, generating the first packet at block  904  comprises generating the first packet to include a first signal field that includes the first indication of the first frequency segment, the first signal field within a first PHY header of the first packet, and generating the second packet at block  908  comprises generating the second packet to include a second signal field that includes the second indication of the second frequency segment, the second signal field within a second PHY header of the second packet. 
     At block  912 , the communication device simultaneously transmits (e.g., the network interface device  122  transmits, the PHY processor  130  transmits, etc.) the first packet via the first frequency segment and the second packet via the second frequency segment. 
     In some embodiments, the method  900  further comprises: generating the first packet to include a bitmap that indicates the one or more first frequency subchannels within the first frequency segment and the one or more second frequency subchannels within the second frequency segment; and generating the second packet to include the bitmap. 
     In some embodiments, the method  900  further comprises: generating the bitmap, wherein respective bits of the bitmap correspond to respective 20 MHz subchannels of a communication channel that includes the first frequency segment and the second frequency segment. 
     In some embodiments, the method  900  further comprises: generating the bitmap, wherein respective bits of the bitmap correspond to respective 40 MHz subchannels of a communication channel that includes the first frequency segment and the second frequency segment. 
     In some embodiments, the method  900  further comprises: generating a first MAC data unit to include the bitmap; generating the first packet to include the first MAC data unit; generating a second MAC data unit to include the bitmap; and generating the second packet to include the second MAC data unit. 
     In some embodiments, the method  900  further comprises: generating the first packet to include a first bitmap that indicates the one or more first frequency subchannels within the first frequency segment; and generating the second packet to include a second bitmap that indicates the one or more second frequency subchannels within the second frequency segment. 
     In some embodiments, the method  900  further comprises: generating the first packet to include one or more first RTS frames corresponding to the first frequency segment; and generating the second packet to include one or more second RTS frames corresponding to the first frequency segment. 
     In some embodiments, the method  900  further comprises: generating the first packet to include one or more first trigger frames corresponding to the first frequency segment, the one or more first trigger frames configured to prompt another communication device to transmit channel availability information regarding the first frequency segment; and generating the second packet to include one or more second trigger frames corresponding to the second frequency segment, the one or more second trigger frames configured to prompt the other communication device to transmit channel availability information regarding the second frequency segment. 
       FIG. 10A  is a diagram of an example signal field, or a portion of a signal field,  1000  that is transmitted in a particular frequency segment of a communication channel that comprises multiple frequency segments, according to some embodiments. The portion of the signal field  1000  is used as the portion of the signal field  340  of  FIG. 3A , in some embodiments. The signal field  1000  is used as the signal field  384 / 394  of  FIG. 3B , in other embodiments. The signal field  1000  is included in a PHY header of a packet. For ease of explanation, the signal field (or portion of signal field)  1000  is referred to herein as “the signal field  1000 ”. 
     The signal field  1000  includes a bandwidth indicator subfield  1004  that indicates a bandwidth of the frequency segment in which the signal field  1000  is transmitted, according to an embodiment. The signal field  1000  additionally includes a center frequency indicator subfield  1008  that indicates a center frequency of the frequency segment in which the signal field  1000  is transmitted, according to an embodiment. In another embodiment, the center frequency indicator subfield  1008  is replaced with a start subchannel indicator subfield that indicates a lowest (in frequency) subchannel of the frequency segment which the signal field  1000  is transmitted. Together, the bandwidth indicator subfield  1004  and the center frequency indicator (or start subchannel indicator) subfield  1008  indicate one or more subchannels in which the signal field  1000  is transmitted. 
     The signal field  1000  additionally includes a punctured channel indicator subfield  1012  that indicates which subchannel(s) (if any) in the frequency segment are punctured, according to an embodiment. In some embodiments, the punctured channel indicator subfield  1012  indicates which subchannel(s) (if any) in an overall channel (which includes the frequency segment and one or more other frequency segments) are punctured. In an embodiment, the punctured channel indicator subfield  1012  includes a bitmap that consists of eight bits corresponding to eight respective 20 MHz subchannels, up to eight of which may be included in the frequency segment. In another embodiment, the punctured channel indicator subfield  1012  includes a bitmap that consists of sixteen bits corresponding to sixteen respective 20 MHz subchannels, up to sixteen of which may be included in an overall channel (which includes the frequency segment and one or more other frequency segments). In another embodiment, the punctured channel indicator subfield  1012  includes a bitmap that consists of eight bits corresponding to eight respective 40 MHz subchannels, up to eight of which may be included in an overall channel (which includes the frequency segment and one or more other frequency segments). 
     The signal field  1000  additionally includes a duration indicator subfield  1016  that indicates a duration of a packet within the frequency segment, the packet including the signal field  1000 , according to an embodiment. 
     In some embodiments, the signal field  1000  additionally includes a spectrum segment ID subfield  1020  that indicates a spectrum segment in which the signal field  1000  is transmitted. 
     In various embodiments, one of, or any suitable combination of two or more of, the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020  are omitted from the signal field  1000 . 
       FIG. 10B  is a diagram of an example service field  1030  that is transmitted in a particular frequency segment of a communication channel that comprises multiple frequency segments, according to some embodiments. The service field  1030  is used as the service field  434 / 438  of  FIG. 4 , in some embodiments. 
     In various embodiments, the service field  1030  includes one of, or any suitable combination of two or more of, the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020  discussed above with reference to  FIG. 10A . 
       FIG. 10C  is a diagram of an example MAC header  1060  that is transmitted in a particular frequency segment of a communication channel that comprises multiple frequency segments, according to some embodiments. The MAC header  1060  is used as the MAC header  504  of  FIG. 5A , in some embodiments. 
     In various embodiments, the MAC header  1060  includes one of, or any suitable combination of two or more of, the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020  discussed above with reference to  FIG. 10A . 
     The MAC header  1060  is part of a MAC frame that includes the RTS frame  608  of  FIGS. 6 and 7 , according to some embodiments. In other embodiments, the RTS frame  608  of  FIGS. 6 and 7  does not include the MAC header  1060 . The MAC header  1060  is part of a MAC frame that includes the CTS frame  616  of  FIGS. 6 and 7 , according to some embodiments. In other embodiments, the CTS frame  616  of  FIGS. 6 and 7  does not include the MAC header  1060 . The MAC header  1060  is part of a MAC frame that includes the trigger frame  808  of  FIG. 8 , according to some embodiments. In other embodiments, the trigger frame  808  of  FIG. 8  does not include the MAC header  1060 . The MAC header  1060  is included in the QoS Null frame  816  of  FIG. 8 , according to some embodiments. In other embodiments, the QoS Null frame  816  of  FIG. 8  does not include the MAC header  1060 . 
       FIG. 10D  is a diagram of an example MAC data portion  1080  that is transmitted in a particular frequency segment of a communication channel that comprises multiple frequency segments, according to some embodiments. The MAC data portion  1080  is used as the MAC data portion  558  of  FIG. 5B , in some embodiments. 
     In various embodiments, the MAC header portion  1080  includes one of, or any suitable combination of two or more of, the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020  discussed above with reference to  FIG. 10A . 
     The MAC data portion  1080  includes the RTS frame  608  of  FIGS. 6 and 7 , according to some embodiments. In other embodiments, the RTS frame  608  of  FIGS. 6 and 7  is not part of the MAC data portion  1080 . The MAC data portion  1080  includes the CTS frame  616  of  FIGS. 6 and 7 , according to some embodiments. In other embodiments, the CTS frame  616  of  FIGS. 6 and 7  is not part of the MAC data portion  1080 . The MAC data portion  1080  includes the trigger frame  808  of  FIG. 8 , according to some embodiments. In other embodiments, the trigger frame  808  of  FIG. 8  is not part of the MAC data portion  1080 . 
     In various embodiments, a packet includes i) the signal field  1000  ( FIG. 10A ) and/or the service field  1030  ( FIG. 10B ) and ii) the MAC header  1060  and/or the MAC data portion  1080 , and the signal field  1000  ( FIG. 10A ) and/or the service field  1030  ( FIG. 10B ) includes one or more of the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020 , and the MAC header  1060  and/or the MAC data portion  1080  include one or more of the bandwidth indicator subfield  1004 , the center frequency (or start subchannel) indicator subfield  1008 , the punctured subchannel indictor subfield  1012 , the duration indicator subfield  1016 , and the spectrum segment ID subfield  1020 . 
     At least some of the various blocks, operations, and techniques described above may be implemented utilizing hardware, a processor executing firmware instructions, a processor executing software instructions, or any combination thereof. When implemented utilizing a processor executing software or firmware instructions, the software or firmware instructions may be stored in any suitable computer readable memory such as a random access memory (RAM), a read only memory (ROM), a flash memory, etc. The software or firmware instructions may include machine readable instructions that, when executed by one or more processors, cause the one or more processors to perform various acts. 
     When implemented in hardware, the hardware may comprise one or more of discrete components, an integrated circuit, an application-specific integrated circuit (ASIC), a programmable logic device (PLD), etc. 
     While the present invention has been described with reference to specific examples, which are intended to be illustrative only and not to be limiting of the invention, changes, additions and/or deletions may be made to the disclosed embodiments without departing from the scope of the invention.