Patent Publication Number: US-9847896-B2

Title: Method, apparatus, and computer readable medium for signaling high efficiency packet formats using a legacy portion of the preamble in wireless local-area networks

Description:
PRIORITY CLAIM 
     This application claims the benefit of priority under 35 USC 119(e) to U.S. Provisional patent application Ser. No. 62/106,039, filed Jan. 21, 2015, and U.S. Provisional patent application Ser. No. 62/105,822, filed Jan. 21, 2015, which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Some embodiments relate to transmitting and receiving preambles in wireless local area networks (WLANs) including networks operating in accordance with the Institute of Electronic and Electrical Engineers (IEEE) 802.11 family of standards. Some embodiments relate to signaling formats of high-efficiency (HE) WLANs (HEW) packets in a legacy preamble. Some embodiments relate to using a modulation and coding scheme (MCS) field of a HEW signal field to jointly signal MCS and low-density parity check (LDPC) and/or a MCS and space-time block coding (STBC). 
     BACKGROUND 
     One issue with communicating data over a wireless network is transmitting and receiving packets that may include preamble fields. Another issue with communicating data over a wireless network is that often more than one standard may be in use in a WLAN. For example, IEEE 802.11ax, which may be referred to as HEW or HE, may need to be used with legacy versions of IEEE 802.11. 
     Thus there are general needs for systems and methods that allow for signaling high-efficiency packet formats using a legacy portion of the preamble of the packet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
         FIG. 1  illustrates a WLAN in accordance with some embodiments; 
         FIG. 2  illustrates a signal constellation that may be used in a signal field to indicate that packets that follow may be for 802.11a, in accordance with some embodiments; 
         FIG. 3  illustrates a series of signal constellations that may be used in a signal field to indicate that packets that follow may be for 802.11n, in accordance with some embodiments; 
         FIG. 4  illustrates a series of signal constellations that may be used in a signal field to indicate that packets that follow may be for 802.11ac, in accordance with some embodiments; 
         FIG. 5  illustrates an IEEE 802.11a/g packet in accordance with some embodiments; 
         FIGS. 6A and 6B  illustrate a HE packet with a single user (SU) preamble where a repeated L-SIG is used to indicate the communication protocol in accordance with some embodiments; 
         FIG. 7  illustrates a HE packet with a multi-user (MU) preamble  703  where a repeated L-SIG is used to indicate the communication protocol in accordance with some embodiments; 
         FIGS. 8 and 9  illustrate tables of the HE-SIG-A format in accordance with some embodiments; 
         FIGS. 10 and 11  illustrate tables of the HE-SIG-A format in accordance with some embodiments; and 
         FIG. 12  illustrates a HEW device, in accordance with example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims. 
       FIG. 1  illustrates a WLAN  100  in accordance with some embodiments. The WLAN may comprise a basis service set (BSS)  100  that may include a master station  102 , which may be an AP, a plurality of high-efficiency wireless (HEW) (e.g., IEEE 802.11ax) STAs  104  and a plurality of legacy (e.g., IEEE 802.11n/ac) devices  106 . 
     The master station  102  may be an AP using the IEEE 802.11 to transmit and receive. The master station  102  may be a base station. The master station  102  may use other communications protocols as well as the IEEE 802.11 protocol. The IEEE 802.11 protocol may be IEEE 802.11ax. The IEEE 802.11 protocol may include using OFDMA, time division multiple access (TDMA), and/or code division multiple access (CDMA). The IEEE 802.11 protocol may include a multiple access technique. For example, the IEEE 802.11 protocol may include space-division multiple access (SDMA) and/or MU-MIMO. 
     The legacy devices  106  may operate in accordance with one or more of IEEE 802.11a/g/ag/n/ac, IEEE 802.11-2012, or another legacy wireless communication standard. The legacy devices  106  may be STAs or IEEE STAs. 
     The HEW STAs  104  may be wireless transmit and receive devices such as cellular telephone, handheld wireless device, wireless glasses, wireless watch, wireless personal device, tablet, or another device that may be transmitting and receiving using the IEEE 802.11 protocol such as IEEE 802.11ax or another wireless protocol. In some embodiments, the HEW STAs  104  may be termed high efficiency (HE) stations. 
     The BSS  100  may operate on a primary channel and one or more secondary channels or sub-channels. The BSS  100  may include one or more master stations  102 . In accordance with some embodiments, the master station  102  may communicate with one or more of the HEW devices  104  on one or more of the secondary channels or sub-channels or the primary channel. In accordance with some embodiments, the master station  102  communicates with the legacy devices  106  on the primary channel. In accordance with some embodiments, the master station  102  may be configured to communicate concurrently with one or more of the HEW STAs  104  on one or more of the secondary channels and a legacy device  106  utilizing only the primary channel and not utilizing any of the secondary channels. 
     The master station  102  may communicate with legacy devices  106  in accordance with legacy IEEE 802.11 communication techniques. In example embodiments, the master station  102  may also be configured to communicate with HEW STAs  104  in accordance with legacy IEEE 802.11 communication techniques. Legacy IEEE 802.11 communication techniques may refer to any IEEE 802.11 communication technique prior to IEEE 802.11ax. 
     In some embodiments, a HEW frame may be configurable to have the same bandwidth as a sub-channel, and the bandwidth may be one of 20 MHz, 40 MHz, or 80 MHz, 160 MHz, 320 MHz contiguous bandwidths or an 80+80 MHz (160 MHz) non-contiguous bandwidth. In some embodiments, bandwidths of 1 MHz, 1.25 MHz, 2.0 MHz, 2.5 MHz, 5 MHz and 10 MHz, or a combination thereof or another bandwidth that is less or equal to the available bandwidth, may also be used. A HEW frame may be configured for transmitting a number of spatial streams, which may be in accordance with MU-MIMO. 
     In other embodiments, the master station  102 , HEW STA  104 , and/or legacy device  106  may also implement different technologies such as code division multiple access (CDMA) 2000, CDMA 2000 1×, CDMA 2000 Evolution-Data Optimized (EV-DO), Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Long Term Evolution (LTE), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), BlueTooth®, or other technologies. 
     Some embodiments relate to HEW communications. In accordance with some IEEE 802.11ax embodiments, a master station  102  may operate as a master station which may be arranged to contend for a wireless medium (e.g., during a contention period) to receive exclusive control of the medium for an HEW control period. In some embodiments, the HEW control period may be termed a transmission opportunity (TXOP). The master station  102  may transmit a HEW master-sync transmission, which may be a trigger frame or HEW control and schedule transmission, at the beginning of the HEW control period. The master station  102  may transmit a time duration of the TXOP and sub-channel information. During the HEW control period, HEW STAs  104  may communicate with the master station  102  in accordance with a non-contention based multiple access technique such as OFDMA or MU-MIMO. This is unlike conventional WLAN communications in which devices communicate in accordance with a contention-based communication technique, rather than a multiple access technique. During the HEW control period, the master station  102  may communicate with HEW stations  104  using one or more HEW frames. During the HEW control period, the HEW STAs  104  may operate on a sub-channel smaller than the operating range of the master station  102 . During the HEW control period, legacy stations refrain from communicating. In accordance with some embodiments, during the master-sync transmission the HEW STAs  104  may contend for the wireless medium with the legacy devices  106  being excluded from contending for the wireless medium during the master-sync transmission. 
     In some embodiments, the multiple-access technique used during the HEW control period may be a scheduled OFDMA technique, although this is not a requirement. In some embodiments, the multiple access technique may be a time-division multiple access (TDMA) technique or a frequency division multiple access (FDMA) technique. In some embodiments, the multiple access technique may be a space-division multiple access (SDMA) technique. 
     The master station  102  may also communicate with legacy stations  106  and/or HEW stations  104  in accordance with legacy IEEE 802.11 communication techniques. In some embodiments, the master station  102  may also be configurable to communicate with HEW stations  104  outside the HEW control period in accordance with legacy IEEE 802.11 communication techniques, although this is not a requirement. 
     In example embodiments, the master station  102  and/or HEW device  104  are configured to perform one or more of the functions and/or methods described herein in conjunction with  FIGS. 1-12  such as, for example, generating an L-SIG to indicate a HE packet format or configuration or detecting that an L-SIG indicates an HE packet format or configuration. Additionally, the master station  102  and/or HEW device  104  may be configured to encode additional format or configuration information in the MCS field and/or using tail bits. 
       FIG. 2  illustrates a signal constellation  200  that may be used in a signal field to indicate that packets that follow may be for 802.11a, in accordance with some embodiments. The horizontal axis may be an in-phase (I)  204  portion of a received signal field, and the vertical axis may be a quadrature portion (Q)  202  portion of the received signal field. The amplitude and phase shift of the received signal field encode information. The dots  206 ,  208  indicate received amplitude and phase combinations of symbols  0   210  and  1   212 , respectively. The power can be measured along the I axis  204  and along the Q axis  202 . A greater power along the I axis  204  may indicate that the signal field is for 802.11a. 
     HEW devices  104  may use the signal constellation  200  to determine the I  204  and Q  202  axes. HEW devices  104  may use the signal constellation  200  to determine that a packet is an 802.11a packet and defer use of the wireless medium based on a length and duration in the 802.11a packet. HEW devices  104  may determine to use the 802.11a standard based on receiving the signal constellation  200 . 
       FIG. 3  illustrates a series  300  of signal constellations  330 ,  360 ,  390  that may be used in a signal field to indicate that packets that follow may be for 802.11n, in accordance with some embodiments. The signal constellations  330 ,  360 ,  390  may be similar to the signal constellation in  FIG. 2 . In the first signal constellation  330 , the dots  302 ,  304  are along the I axis  204 . In the second signal constellation  360 , the dots  306 ,  310  indicate received amplitude and phase combinations of symbols  0   308 , and  1   312 , respectively. The dots  306 ,  310  are along the vertical axis  202 . In the third signal constellation  390 , the dots  314 ,  316  indicate received amplitude and phase combinations of symbols  0   308 , and  1   312 . The dots  314 ,  316  are along the vertical axis  202 . The power can be measured along the I axes  204  and along the Q axes  202 . The first constellation  330  may be used to determine the I axis  204  and the Q axis  202 . A greater power on the Q axis  202  for the second constellation  360 , and a greater power on the Q axis  202  for the third constellation  390 , may indicate that the signal fields may be for 802.11n. The first constellation  330  may be a signal field. The second and third constellations  360 ,  390  may be high-throughput (HT) signal fields. 
     Legacy devices  106  that operate in accordance with 802.11a may not be able to interpret the signal constellation  360  since it is rotated. The first constellation  330  may be a signal field that includes a length field and a rate. The legacy devices  106  then defer for the entire time indicated by the length and the rate. The legacy devices  106  that operate in accordance with 802.11n can then set the length and rate fields of the first constellation  330  for the entire duration of the 802.11 transmission. In this way, the legacy devices  106  that operate in accordance with 802.11n can recognize the second constellation  360  as an HT signal field and the third constellation  390  as an HT signal field and can defer legacy devices  106  operating in accordance with 802.11a. 
     HEW devices  104  may use the signal constellations  330 ,  360 , and/or  390  to determine that a packet is an 802.11n packet and defer use of the wireless medium based on a duration and length in the 802.11n packet, although the scope of the embodiments is not limited in this respect. HEW devices  104  may determine to use the 802.11n standard based on receiving the signal constellations  330 ,  360 ,  390 , although the scope of the embodiments is not limited in this respect. 
       FIG. 4  illustrates a series  400  of signal constellations  430 ,  460 ,  490  that may be used in a signal field to indicate that packets that follow may be for 802.11ac, in accordance with some embodiments. The signal constellations  430 ,  460 ,  490  may be similar to the signal constellation in  FIG. 2 . In the first signal constellation  430 , the dots  402 ,  404  are along the I axis  204 . In the second signal constellation  460 , the dots  406 ,  408  indicate received amplitude and phase combinations of symbols  0   410  and  1   412 , respectively, and the dots  406 ,  408  are along the I axis  204 . In the third signal constellation  490 , the dots  418 ,  414  indicate received amplitude and phase combinations of symbols  0   420  and  1   416 , respectively, and the dots  414 ,  416  are along the Q axis  202 . The power can be measured along the I axes  204  and along the Q axes  202 . The first constellation  430  may be used to determine the I axis  204  and the Q axis  202 . A greater power on the I axis  202  for the second constellation  460 , and a greater power on the Q axis  202  for the third constellation  490  may indicate that the signal fields may be for 802.11ac. The first constellation  430  may be a signal field. The second and third constellations  460 ,  490  may be very high-throughput (VHT) signal fields, which may be termed SIG-A and SIG-B. 
     Legacy devices  106  that operate in accordance with 802.11a may not be able to interpret the signal constellation  490  since it is rotated. The first constellation  430  may be a signal field that includes a length field and a rate. The legacy devices  106  that operate in accordance with 802.11a will defer for the entire time indicated by the length and rate in the first constellation  430 . The legacy devices  106  that operate in accordance with 802.11n will recognize that the second constellation  460  is not rotated so it is not a signal field for 802.11n. The legacy devices  106  that operate in accordance with 802.11n will then defer for the entire time indicated by the length and rate in the first constellation  430 . 
     The legacy devices  106  that operate in accordance with 802.11ac can then set the length and rate fields of the first constellation  430  for the entire duration of the 802.11ac transmission. In this way, the legacy devices  106  that operate in accordance with 802.11ac can recognize second constellation  460  as a VHT signal field and third constellation  490  as a VHT signal field, and can defer legacy devices  106  operating in accordance with 802.11a and 802.11n. 
     HEW devices  104  may use the signal constellations  430 ,  460 , and/or  490  to determine that a packet is an 802.11ac packet and defer use of the wireless medium based on a duration and length in the 802.11ac packet, although the scope of the embodiments is not limited in this respect. HEW devices  104  may determine to use the 802.11ac standard based on receiving the signal constellations  430 ,  460 ,  490 , although the scope of the embodiments is not limited in this respect. 
       FIG. 5  illustrates an IEEE 802.11a/g packet  500  in accordance with some embodiments. The IEEE 802.11a/g packet  500  may be a physical layer convergence procedure (PLCP) protocol data unit (PPDU). Illustrated in  FIG. 5  are legacy short-training field (L-STF)  502 , legacy long-training field (L-LTF)  504 , legacy signal field (L-SIG)  506 , and data  508 . The L-STF  502  and L-LFT  504  may be a legacy fields to train the receiving legacy device  106 , HEW device  104 , and/or master station  102 . The L-SIG  506  may be a legacy field that indicates that the communication protocol is IEEE 802.11a/g. The L-SIG  506  may indicate that the communication protocol is IEEE 802.11a/g as described in conjunction with  FIGS. 2-4 . The legacy devices  106 , HEW stations  104 , and/or master stations  102  may be configured to determine that packet  500  is an IEEE 802.11a/g format based on the L-STF  502 , L-LTF  504 , and L-SIG  506 . The data  508  may be data that may include additional packet formats. 
       FIGS. 6A and 6B  illustrate a HE packet  600 ,  650 , respectively, with a single user (SU) preamble  603  where a repeated L-SIG is used to indicate the communication protocol in accordance with some embodiments. Illustrated in  FIGS. 6A and 6B  are L-STF  602 , L-LTF  604 , L-SIG  606 , L-SIG  608 , high-efficiency signal field A (HE-SIG-A)  610 , a second HE-SIG-A  611  ( FIG. 6B ), high-efficiency short-training field (HE-STF)  612 , and data  614 . The HE packet  600 ,  650  communication protocol, which may be IEEE 802.11ax, may be indicated by two L-SIGs  606 ,  608 . In some embodiments the communication protocol, which may be IEEE 802.11ax, may be indicated in a different way. 
     The HEW devices  104  and master stations  102  may be configured to determine that the packet is an HE packet  600 ,  650  based on the repeated L-SIGs  606 ,  608 . In some embodiments, the HEW devices  104  and master stations  102  may be configured to determine that the packet is an HE packet  600 ,  650  based in a different way. The SU preamble  603  may include L-STF  602 , L-LTF  604 , L-SIG  606 , L-SIG  608 , HE-SIG-A  610 , and HE-STF  612 . The legacy portion  605  of the SU preamble  603  may be the L-STF  602 , L-LTF  604 , L-SIG  606 , and L-SIG  608 . 
     The HE-SIG-A  610  may be two symbols, in accordance with some embodiments. The HE-SIG-A  610  may include information that indicates a packet format common for both a SU preamble  603  and a MU preamble  703  ( FIG. 7 ) for HE packets  600 ,  700  such as a BSS-color, a bandwidth (BW), a cyclic redundancy code (CRC), and tail bits. The HE-SIG-A  610  may also include information that indicates a modulation and coding scheme (MSC) for a HE-SIG-B that may be included in some HE packets  600 ,  650 . In some embodiments, the HE-SIG-A  610  may include information that indicates a number of symbols of a HE-SIG-B and a guard interval used by the HE-SIG-B. 
     As illustrated in  FIG. 6B , the HE-SIG-A  611  may be a second symbol of the HE-SIG-A  610 . In some embodiments the HE-SIG-A  611  is a repeat of the HE-SIG-A  610 . In some embodiments HE-SIG-A  611  is not included in the HE-packet  600 ,  650 . 
     A HEW device  104  and/or master station  102  may be able to more quickly decode a packet  600 ,  650 ,  700  if the format of the packet is signaled in the legacy portion  605  of the preamble  603 ,  703 . In some embodiments, the HE packet  600 ,  650  with a SU preamble may include a HE-SIG-G field. 
       FIG. 7  illustrates a HE packet  700  with a multi-user (MU) preamble  703  where a repeated L-SIG is used to indicate the communication protocol in accordance with some embodiments. Illustrated in  FIG. 7  are L-STF  702 , L-LTF  704 , L-SIG  706 , L-SIG  708 , HE-SIG-A  710 , HE-SIG-B  711 , HE-STF  712 , and data  714 . The HE packet  700  may be an IEEE 802.11ax. The HE packet  700  communication protocol, which may be IEEE 802.11ax, may be indicated by two L-SIGs  706 ,  708 . In some embodiments the communication protocol, which may be IEEE 802.11ax, may be indicated in a different way. The HEW devices  104  and master stations  102  may be configured to determine that the packet is an HE packet  700  based on the repeated L-SIGs  706 ,  708 . The MU preamble  703  may include L-STF  702 , L-LTF  704 , L-SIG  706 , L-SIG  708 , HE-SIG-A  710 , HE-SIG-B  711 , and HE-STF  712 . The legacy portion  705  of the MU preamble  703  may be the L-STF  702 , L-LTF  704 , and L-SIG  706 . 
     The HE-SIG-A  710  may be two symbols, in accordance with some embodiments. The HE-SIG-A  710  may include information that indicates a packet format common for both a SU preamble  603  ( FIG. 6 ) and a MU preamble  703  for HE packets  600 ,  700  such as a BSS-color, a bandwidth (BW), a cyclic redundancy code (CRC), and tail bits. The HE-SIG-A  710  may also include information that indicates a modulation and coding scheme (MSC) for a HE-SIG-B that may be included in some HE packets  700 . In some embodiments, the HE-SIG-A  710  may include information that indicates a number of symbols of the HE-SIG-B  711  and a guard interval used by the HE-SIG-B. 
     A HEW device  104  and/or master station  102  may be able to more quickly decode a packet  600 ,  700  if the format of the packet is signaled in the legacy portion  705  of the preamble  603 ,  703 . 
     Referring to  FIGS. 6 and 7 , the legacy portion  605 ,  705  may indicate a packet format for the HE packet  600 ,  650 ,  700 . For example, L-SIG  606 ,  706  may include a length  607 ,  707 . The length of the L-SIG  606 ,  706  may need to be zero (mod 3) for legacy device  106 , HEW devices  104 , and master devices  102  to identify the communication protocol as IEEE 802.11ac. Legacy devices  106  will defer for whatever the length field in the L-SIG  606 ,  706  indicates. The length  607 ,  707  field may be used to signal a format of the HE packet  600 ,  650 ,  700 . For example, length  607 ,  707  (mod 3)=1 may indicate that the HE packet  600 ,  650 ,  700  is a HE packet  600 ,  650 ,  700  for with a SU preamble  603 ,  703 . Referring to  FIG. 7 , length  707  (mod 3)=2 may indicate that the HE packet  700  is a HE packet  700  with a MU preamble  703 . 
     In some embodiments, the length  607 ,  707  field may be used to signal either an indoor or outdoor preamble format. The indoor or outdoor preamble format may indicate a guard interval for the HE-SIG-B  711 . The indoor or outdoor preamble format may indicate a symbol size for a HE long-training field (HE-LTF). 
     In some embodiments, the legacy preamble  605 ,  705  may indicate two or more packet formats. For example, the length  607 ,  707  may be used to indicate whether the packet format is an SU format or a MU format, and a polarity of a repeated L-SIG  608 ,  708  may be used to indicate whether the packet format is an indoor format or an outdoor format. In some embodiments, different portions of the legacy preamble  605 ,  705  may be used to indicate different packet formats. 
       FIGS. 8 and 9  illustrate tables  800 ,  900 , respectively, of the HE-SIG-A format in accordance with some embodiments.  FIGS. 8 and 9  are described in conjunction with one another. In some embodiments the HE-SIG-A may have two formats either an SU format  802 ,  902  or an MU format  804 ,  904 . In some embodiments, the format of the HE-SIG-A is signaled in the legacy preamble  605 ,  705 . Both the SU format  802 ,  902  and the MU format  804 ,  904  may include a bandwidth (BW), BSS color, CRC, and tail. The BW may be two bits and may indicate a bandwidth. The BSS color may be four to six bits and may be an identifier of a BSS. Illustrated in  FIG. 8  is BSS color with 6 bits and in  FIG. 9  BSS with 4 bits. 
     Illustrated in  FIG. 9  are two additional fields an indication of whether low-density parity-check (LDPC) is used and an indication of whether space-time block coding (STBC) is used. In some embodiments, two bits may be used to indicate a STBC configuration. In some embodiments the indication of whether LDPC is used also indicates whether or not binary convolution coding (BCC) is used. 
     The CRC may be four bits. The tail may be six bits and may be bits for unwinding the convolution code. The SU format  802 ,  902  may include number of spatial streams (NSTS), MCS, and beamformed. The NSTS, which may be three bits, may indicate a number of spatial streams. MCS, which may be four bits, may be an indication of the modulation and coding scheme (MCS) used to encode a remaining portion of the packet. 
     The MU format  804 ,  904  may include number of symbols (NSYM) for HE-SIG-B  711  and MCS for HE-SIG-B  711 . NSYM may be three bits and may be a number of symbols of the HE-SIG-B  711 . The MCS for HE-SIG-B may be two bits and may be an MCS for the HE-SIG-B  711 . In some embodiments, the SU format  802 ,  902  may be 26 bits and the MU format  804 ,  904  may be 23 bits. An example of the number of bits that may be used for the fields of the SU format  802 ,  902  and MU format  804 ,  904  have been described, but a different number of bits may be used. 
     In example embodiments, tail biting may be used where some or all of the 6 bits of the tail are not included. The 6 bits may be used to signal one or more of LDPC or BCC coding, and/or an STBC configuration. As indicated at  806 ,  906  in some embodiments the 6 bits may be used to signal a clear channel assessment (CCA) margin/densification (3 bits) and/or length ambiguity. 
       FIGS. 10 and 11  illustrate tables  1000 ,  1100 , respectively, of the HE-SIG-A format in accordance with some embodiments.  FIGS. 10 and 11  will be described together. In some embodiments the HE-SIG-A may have two formats either an SU format  1002 ,  1102  or an MU format  1004 ,  1104 . In some embodiments, the format of the HE-SIG-A  610 ,  710  is signaled in the legacy preamble  605 ,  705 . Both the SU format  1002 ,  1102  and the MU format  1004 .  1104  may include a bandwidth (BW), BSS color, CRC, and tail. The BW may be two bits and may indicate a bandwidth. The BSS color may be six bits as illustrated in table  1000  or 4 bits as illustrated in table  1100  and may be an identifier of a BSS. 
     Illustrated in  FIG. 11  are two additional fields an indication of whether low-density parity-check (LDPC) is used and an indication of whether space-time block coding (STBC) is used. In some embodiments, two bits may be used to indicate a STBC configuration. In some embodiments the indication of whether LDPC is used also indicates whether or not binary convolution coding (BCC) is used. 
     The CRC may be four bits. The SU format  1002 ,  1102  may include NSTS, MCS, coding, GI for data, and beamformed. The NSTS may be three bits and may indicate a number of spatial streams. MCS, which may be four bits, and may be an indication of the modulation and coding scheme (MCS) used to encode a remaining portion of the packet. Coding may be one bit and may indicate whether or not the remaining portion of the packet is coded. The GI for data may be one bit and may be an indication of a guard interval for the remaining portion of the packet such as the data. Beam formed, which may be one bit, may indicate whether or not beam forming is used for the packet. 
     The MU format  1004 ,  1104  may include NSYM for HE-SIG-B  711  and MCS for HE-SIG-B  711 . NSYM may be three bits and may be a number of symbols of the HE-SIG-B  711 . The MCS for HE-SIG-B may be two bits and may be an MCS for the HE-SIG-B  711 . 
     The tail may be six bits and may be bits for unwinding the convolution code. In example embodiments, tail biting may be used where some or all of the 6 bits of the tail are not included. The 6 bits may be used to signal one or more of LDPC or BCC coding, and/or an STBC configuration. As indicated at  1006 ,  1106  in some embodiments the 6 bits may be used to signal a clear channel assessment (CCA) margin/densification (3 bits) and/or length ambiguity. 
     Referring to  FIGS. 8, 9, 10, and 11  at  808 ,  908 ,  1008 ,  1108 , the MCS field may be used to signal one or more other fields. For example, to signal MCS may only require a value for MCS from zero to ten. This may leave five extra values in a four bit MCS field that are not utilized. These extra values or bits may be used to signal other fields. In example embodiments, a portion of the MCS field may be used where some or all of the four bits of the MCS are used to signal one or more of LDPC or BCC and/or an STBC configuration. 
     In example embodiments, if there are N values to use for signaling a joint MCS and STBC, then the specified MCS&#39;s to operate with STBC may be mapped to the MCS values. For example if we have five values that can be signaled, and then want to use MCS 0 through MCS 4 to be used with STBC, then MCS 0 with STBC would be signaled as MCS 11 in the HE-SIG-A  610 ,  710  MCS field. MCS 1 with STBC would be signaled as MCS 12, etc. In example embodiments values are chosen to improve performance, for example, instead of MCS 0-4, the values MCS 0, MCS 2, MCS 4, MCS 6 and MCS 10 could be used, which may improve performance by using different bits. 
     In some embodiments LDPC and MCS may jointed be signaled. In some embodiments a reduced MCS field with STBC and/or a reduced MCS field with LDPC could be jointly signaled using values of MCS that are not used to signal MCS values. For example, N values of MCS may be used to signal STBC, and 5-N may be used to signal LDPC. In some embodiments the MCS values of 11-15 may be used to jointly signal MCS and/or LDPC, and/or used to jointly signal the MCS and the STBC values. 
     In some embodiments, signaling a configuration in the legacy preamble  605 ,  705 , before HE signaling, may convey the location of an HE-STF, existence of an HE-SIG-B and length of the guard interval for HE-SIG-B, and/or a symbol size of HE-LTFs. Thus, configurations could be used immediately after the L-SIG, and signaled using the L-SIG, so that the HEW station  104  and/or master station  102  would know the configurations after detecting the L-SIG. 
     In some embodiments, the SU format  802 ,  902 ,  1002 ,  1102  may be 26 bits and the MU format  804 ,  904 ,  1004 ,  1104  may be 23 bits. An example of the number of bits that may be used for the fields of the SU format  802 ,  902 ,  1002 ,  1102  and MU format  804 ,  904 ,  1004 ,  1104  has been described, but a different number of bits may be used. Moreover, the SU format  802 ,  902 ,  1002 ,  1102  and MU format  804 ,  904 ,  1004 ,  1104  may include fewer or more fields. 
       FIG. 12  illustrates a HEW device in accordance with some embodiments. HEW device  1200  may be an HEW compliant device that may be arranged to communicate with one or more other HEW devices, such as HEW STAs  104  ( FIG. 1 ) or master station  102  ( FIG. 1 ) as well as communicate with legacy devices  106  ( FIG. 1 ). HEW STAs  104  and legacy devices  106  may also be referred to as HEW devices and legacy STAs, respectively. HEW device  1200  may be suitable for operating as master station  102  ( FIG. 1 ) or a HEW STA  104  ( FIG. 1 ). In accordance with embodiments, HEW device  1200  may include, among other things, a transmit/receive element  1201  (for example an antenna), a transceiver  1202 , physical (PHY) circuitry  1204 , and media access control (MAC) circuitry  1206 . PHY circuitry  1204  and MAC circuitry  1206  may be HEW compliant layers and may also be compliant with one or more legacy IEEE 802.11 standards. MAC circuitry  1206  may be arranged to configure packets such as a physical layer convergence procedure (PLCP) protocol data unit (PPDUs) and arranged to transmit and receive PPDUs, among other things. HEW device  1200  may also include circuitry  1208  and memory  1210  configured to perform the various operations described herein. The circuitry  1208  may be coupled to the transceiver  1202 , which may be coupled to the transmit/receive element  1201 . While  FIG. 12  depicts the circuitry  1208  and the transceiver  1202  as separate components, the circuitry  1208  and the transceiver  1202  may be integrated together in an electronic package or chip. 
     In some embodiments, the MAC circuitry  1206  may be arranged to contend for a wireless medium during a contention period to receive control of the medium for the HEW control period and configure an HEW PPDU. In some embodiments, the MAC circuitry  1206  may be arranged to contend for the wireless medium based on channel contention settings, a transmitting power level, and a CCA level. 
     The PHY circuitry  1204  may be arranged to transmit the HEW PPDU. The PHY circuitry  1204  may include circuitry for modulation/demodulation, upconversion/downconversion, filtering, amplification, etc. In some embodiments, the circuitry  1208  may include one or more processors. The circuitry  1208  may be configured to perform functions based on instructions being stored in a RAM or ROM, or based on special purpose circuitry. The circuitry  1208  may be termed processing circuitry in accordance with some embodiments. The circuitry  1208  may include a processor such as a general purpose processor or special purpose processor. The circuitry  1208  may implement one or more functions associated with transmit/receive elements  1201 , the transceiver  1202 , the PHY circuitry  1204 , the MAC circuitry  1206 , and/or the memory  1210 . 
     In some embodiments, the circuitry  1208  may be configured to perform one or more of the functions and/or methods described herein and/or in conjunction with  FIGS. 1-12  such as, for example, generating an L-SIG to indicate a HE packet format or configuration or detecting that an L-SIG indicates an HE packet format or configuration. Additionally, the master station  102  and/or HEW device  104  may be configured to encode additional format or configuration information in the MCS field and/or using tail bits. 
     In some embodiments, the transmit/receive elements  1201  may be two or more antennas that may be coupled to the PHY circuitry  1204  and arranged for sending and receiving signals including transmission of the HEW packets. The transceiver  1202  may transmit and receive data such as HEW PPDU and packets that include an indication that the HEW device  1200  should adapt the channel contention settings according to settings included in the packet. The memory  1210  may store information for configuring the other circuitry to perform operations for configuring and transmitting HEW packets and performing the various operations to perform one or more of the functions and/or methods described herein and/or in conjunction with  FIGS. 1-12  such as, for example, generating an L-SIG to indicate a HE packet format or configuration or detecting that an L-SIG indicates an HE packet format or configuration. Additionally, the master station  102  and/or HEW device  104  may be configured to encode additional format or configuration information in the MCS field and/or using tail bits. 
     In some embodiments, the HEW device  1200  may be configured to communicate using OFDM communication signals over a multicarrier communication channel. In some embodiments, HEW device  1200  may be configured to communicate in accordance with one or more specific communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) standards including IEEE 802.11-2012, 802.11n-2009, 802.11ac-2013, 802.11ax, DensiFi, standards and/or proposed specifications for WLANs, or other standards as described in conjunction with  FIG. 1 , although the scope of the invention is not limited in this respect as they may also be suitable to transmit and/or receive communications in accordance with other techniques and standards. In some embodiments, the HEW device  1200  may use 4× symbol duration of 802.11n or 802.11ac. 
     In some embodiments, an HEW device  1200  may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), an access point, a base station, a transmit/receive device for a wireless standard such as 802.11 or 802.16, or other device that may receive and/or transmit information wirelessly. In some embodiments, the mobile device may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen. 
     The transmit/receive element  1201  may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MIMO) embodiments, the antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result. 
     Although the HEW device  1200  is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements. 
     The following examples pertain to further embodiments. Example 1 is an apparatus of a high-efficiency (HE) wireless local area network (HEW) device, including circuitry configured to: generate a HE packet comprising a legacy signal field (L-SIG) followed by one or more HE signal fields, where the one or more HE signal fields comprises a HE-SIG-A field, and where a modulation and coding scheme (MCS) sub-field of the HE-SIG-A field jointly signals a MCS and one or more other sub-fields; and transmit the HE packet to one or more HEW devices. 
     In Example 2, the subject matter of Example 1 can optionally include where the one or more other subfields are from the following group: a low-density parity check (LDPC) and a space-time block coding (STBC). 
     In Example 3, the subject matter of Examples 1 and 2 can optionally include where the circuitry is further configured to: generate the L-SIG to signal to the one or more HEW devices either a first packet format of the HE packet or a second packet format of the HE packet, wherein a length of the L-SIG modulo 3 is used to signal the first packet format or the second packet format. 
     In Example 4, the subject matter of Example 3 can optionally include where the first packet format or the second packet format of the HE packet is at least one from the following group: a single user format or a multiple user format; and, an indoor format or an outdoor format. 
     In Example 5, the subject matter of Example 4 can optionally include where the circuitry is to configure a length field of the L-SIG to be a one or two modulo of three (MOD 3) to indicate the first packet format or the second packet format. 
     In Example 6, the subject matter of Example 4 can optionally include where the single user format and the multiple user format indicate at least a number of HE-SIG-B symbols. 
     In Example 7, the subject matter of Example 4 can optionally include where the indoor format and the outdoor format indicate a guard interval for a HE-SIG-B and a HE-long training field (LTF) symbol size. 
     In Example 8, the subject matter of any of Examples 1-7 can optionally include where the circuitry is to generate a duplicated L-SIG field with a polarity difference to indicate a third packet configuration of the HE packet or a fourth packet configuration of the HE packet. 
     In Example 9, the subject matter of Example 8 can optionally include where third packet configuration or the fourth packet configuration are one from the following group: a single user configuration or a multiple user configuration; and, an indoor configuration or an outdoor configuration. 
     In Example 10, the subject matter of any of Examples 1-9 can optionally include where the circuitry further comprises processing circuitry and transceiver circuitry. 
     In Example 11, the subject matter of Example 10 can optionally include where the circuitry is configured to operate in accordance with orthogonal frequency division multiple access (OFDMA) and Institute of Electronic and Electrical Engineers (IEEE) 802.11ax. 
     In Example 12, the subject matter of Example 10 can optionally include where the circuitry is further configured to transmit a trigger frame to the one or more HEW devices, the trigger frame to include a duration and frequency allocation for each of the one or more HEW devices for a transmit opportunity; and where the circuitry is configured to generate a second HE packet without the L-SIG field within the transmit opportunity. 
     In Example 13, the subject matter of any of Examples 1-12 can optionally include where the HEW device is one from the following group: an access point, a master station, and a HEW station. 
     In Example 14, the subject matter of any of Examples 1-13 can optionally include where the one or more HE signal fields comprise at least one from the following group: a clear channel assessment (CCA) margin/densification and length ambiguity. 
     In Example 15, the subject matter of any of Examples 1-14 can optionally include memory coupled to the circuitry; and one or more antennas coupled to the circuitry. 
     Example 16 is a method to signal a packet configuration performed by a high-efficiency (HE) wireless local area network (WLAN) (HEW) device. The method including generating a HE packet comprising a legacy signal field (L-SIG) followed by one or more HE signal fields, wherein the one or more HE signal fields comprises a HE-SIG-A field, and wherein a modulation and coding scheme (MCS) sub-field of the HE-SIG-A field jointly signals a MCS and one or more other sub-fields; and transmitting the HE packet to one or more HEW devices. 
     In Example 17, the subject matter of Example 16 can optionally include where the one or more other sub-fields are from the following group: a low-density parity check (LDPC) and a space-time block coding (STBC). 
     In Example 18, the subject matter of Examples 16 and 17 can optionally include generating the L-SIG to signal to the one or more HEW devices either a first packet format of the HE packet or a second packet format of the HE packet, wherein a length of the L-SIG modulo 3 is used to signal the first packet format or the second packet format. 
     Example 19 is an apparatus of a high-efficiency (HE) station comprising circuitry configured to: receive a packet from a second HE station, the packet to include at least a legacy signal field (L-SIG); determine whether the L-SIG indicates that the packet is a HE packet; defer based on information in the L-SIG if the L-SIG indicates that the packet is not the HE-packet; and if the L-SIG indicates that the packet is the HE-packet, determine from one sub-field of one or more HE signal fields a modulation and coding scheme (MCS) for a data portion of the packet and a low-density parity check (LDPC) or a space-time block coding (STBC) from the one sub-field of the one or more HE signal fields, wherein the HE-packet comprises the one or more signal fields. 
     In Example 20, the subject matter of Example 19 can optionally include where the one or more HE signal fields comprise a HE-SIG-A field and wherein the HE-SIG-A field comprises the one sub-field. 
     In Example 21, the subject matter of Examples 19 and 20 can optionally include where the circuitry is further configured to: determine whether the packet is a first packet format of the HE packet or a second packet format of the HE packet, wherein a length of the L-SIG modulo 3 is used to signal the first packet format or the second packet format. 
     In Example 22, the subject matter of any of Examples 19-21 can optionally include memory coupled to the circuitry; and, one or more antennas coupled to the circuitry. 
     Example 23 is a non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of a high-efficiency (HE) wireless local-area network (WLAN) (HEW) device, the operations to configure the one or more processors to cause the HEW master station to: generate a HE packet comprising a legacy signal field (L-SIG) followed by one or more HE signal fields, wherein the one or more HE signal fields comprises a HE-SIG-A field, and wherein a modulation and coding scheme (MCS) sub-field of the HE-SIG-A field jointly signals a MCS and one or more other sub-fields; and transmit the HE packet to one or more HEW devices. 
     In Example 24, the subject matter of Example 23 can optionally include where the one or more other sub-fields are from the following group: a low-density parity check (LDPC) and a space-time block coding (STBC). 
     In Example 25, the subject matter of Examples 23 and 24 can optionally include where the instructions are further configured to cause the HEW device to: generate the L-SIG to signal to the one or more HEW devices either a first packet format of the HE packet or a second packet format of the HE packet, wherein a length of the L-SIG modulo 3 is used to signal the first packet format or the second packet format. 
     The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.