Patent Publication Number: US-2023148403-A1

Title: Preamble for extended range (er) ppdu transmission over wide channel bandwidths

Description:
TECHNICAL FIELD 
     Embodiments pertain to wireless communications. Some embodiments relate wireless local area networks (WLANs) that operate in accordance with the IEEE 802.11 standards. Some embodiments relate to IEEE 802.11be Extremely High Throughput (EHT) (i.e., the IEEE P802.11-Task Group BE EHT) (Wi-Fi 7). Some embodiments relate to next generation Wi-Fi (Wi-Fi 8). 
     BACKGROUND 
     One issue with communicating data over a wireless network is range. For longer-range transmission, lower received signal levels make it difficult for a receiver to properly detect and decode packets. This is particularly an issue with wideband transmissions in WLANs as a receiving station (STA) may not be able to detect and/or properly decode a preamble of a physical layer protocol data unit (PPDU). Thus what is needed is a PPDU for extended range communications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of a radio architecture, in accordance with some embodiments. 
         FIG.  2    illustrates a front-end module circuitry for use in the radio architecture of  FIG.  1   , in accordance with some embodiments. 
         FIG.  3    illustrates a radio IC circuitry for use in the radio architecture of  FIG.  1   , in accordance with some embodiments. 
         FIG.  4    illustrates a baseband processing circuitry for use in the radio architecture of  FIG.  1   , in accordance with some embodiments. 
         FIG.  5    illustrates a WLAN, in accordance with some embodiments. 
         FIG.  6    illustrates an extended range (ER) PPDU, in accordance with some embodiments. 
         FIG.  7    illustrates an ER PPDU, in accordance with some other 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. 
     In some embodiments, a physical layer protocol data unit (PPDU) may include legacy preamble fields followed by a universal signal field (U-SIG). For an extended range (ER) transmission, the U-SIG may be encoded to indicate via a bit whether the PPDU is an ER PPDU or a non-ER PPDU. When the U-SIG is encoded to indicate that the PPDU is an ER PPDU, the PPDU may include ER preamble fields following the U-SIG and an ER data field following the ER preamble fields. The ER preamble fields may comprise pre-ER modulated fields followed by ER modulated fields. The pre-ER modulate fields may comprise an ER short training field (ER-STF) followed by an ER long training field (ER-LTF) followed by an ER signal field (ER-SIG). The ER modulated fields may comprise at least the ER data field. These embodiments, as well as others, are described in more detail below. 
       FIG.  1    is a block diagram of a radio architecture  100  in accordance with some embodiments. Radio architecture  100  may include radio front-end module (FEM) circuitry  104 , radio IC circuitry  106  and baseband processing circuitry  108 . Radio architecture  100  as shown includes both Wireless Local Area Network (WLAN) functionality and Bluetooth (BT) functionality although embodiments are not so limited. In this disclosure, “WLAN” and “Wi-Fi” are used interchangeably. 
     FEM circuitry  104  may include a WLAN or Wi-Fi FEM circuitry  104 A and a Bluetooth (BT) FEM circuitry  104 B. The WLAN FEM circuitry  104 A may include a receive signal path comprising circuitry configured to operate on WLAN RF signals received from one or more antennas  101 , to amplify the received signals and to provide the amplified versions of the received signals to the WLAN radio IC circuitry  106 A for further processing. The BT FEM circuitry  104 B may include a receive signal path which may include circuitry configured to operate on BT RF signals received from one or more antennas  101 , to amplify the received signals and to provide the amplified versions of the received signals to the BT radio IC circuitry  106 B for further processing. FEM circuitry  104 A may also include a transmit signal path which may include circuitry configured to amplify WLAN signals provided by the radio IC circuitry  106 A for wireless transmission by one or more of the antennas  101 . In addition, FEM circuitry  104 B may also include a transmit signal path which may include circuitry configured to amplify BT signals provided by the radio IC circuitry  106 B for wireless transmission by the one or more antennas. In the embodiment of  FIG.  1   , although FEM  104 A and FEM  104 B are shown as being distinct from one another, embodiments are not so limited, and include within their scope the use of an FEM (not shown) that includes a transmit path and/or a receive path for both WLAN and BT signals, or the use of one or more FEM circuitries where at least some of the FEM circuitries share transmit and/or receive signal paths for both WLAN and BT signals. 
     Radio IC circuitry  106  as shown may include WLAN radio IC circuitry  106 A and BT radio IC circuitry  106 B. The WLAN radio IC circuitry  106 A may include a receive signal path which may include circuitry to down-convert WLAN RF signals received from the FEM circuitry  104 A and provide baseband signals to WLAN baseband processing circuitry  108 A. BT radio IC circuitry  106 B may in turn include a receive signal path which may include circuitry to down-convert BT RF signals received from the FEM circuitry  104 B and provide baseband signals to BT baseband processing circuitry  108 B. WLAN radio IC circuitry  106 A may also include a transmit signal path which may include circuitry to up-convert WLAN baseband signals provided by the WLAN baseband processing circuitry  108 A and provide WLAN RF output signals to the FEM circuitry  104 A for subsequent wireless transmission by the one or more antennas  101 . BT radio IC circuitry  106 B may also include a transmit signal path which may include circuitry to up-convert BT baseband signals provided by the BT baseband processing circuitry  108 B and provide BT RF output signals to the FEM circuitry  104 B for subsequent wireless transmission by the one or more antennas  101 . In the embodiment of  FIG.  1   , although radio IC circuitries  106 A and  106 B are shown as being distinct from one another, embodiments are not so limited, and include within their scope the use of a radio IC circuitry (not shown) that includes a transmit signal path and/or a receive signal path for both WLAN and BT signals, or the use of one or more radio IC circuitries where at least some of the radio IC circuitries share transmit and/or receive signal paths for both WLAN and BT signals. 
     Baseband processing circuitry  108  may include a WLAN baseband processing circuitry  108 A and a BT baseband processing circuitry  108 B. The WLAN baseband processing circuitry  108 A may include a memory, such as, for example, a set of RAM arrays in a Fast Fourier Transform or Inverse Fast Fourier Transform block (not shown) of the WLAN baseband processing circuitry  108 A. Each of the WLAN baseband circuitry  108 A and the BT baseband circuitry  108 B may further include one or more processors and control logic to process the signals received from the corresponding WLAN or BT receive signal path of the radio IC circuitry  106 , and to also generate corresponding WLAN or BT baseband signals for the transmit signal path of the radio IC circuitry  106 . Each of the baseband processing circuitries  108 A and  108 B may further include physical layer (PHY) and medium access control layer (MAC) circuitry and may further interface with application processor  111  for generation and processing of the baseband signals and for controlling operations of the radio IC circuitry  106 . 
     Referring still to  FIG.  1   , according to the shown embodiment, WLAN-BT coexistence circuitry  113  may include logic providing an interface between the WLAN baseband circuitry  108 A and the BT baseband circuitry  108 B to enable use cases requiring WLAN and BT coexistence. In addition, a switch  103  may be provided between the WLAN FEM circuitry  104 A and the BT FEM circuitry  104 B to allow switching between the WLAN and BT radios according to application needs. In addition, although the antennas  101  are depicted as being respectively connected to the WLAN FEM circuitry  104 A and the BT FEM circuitry  104 B, embodiments include within their scope the sharing of one or more antennas as between the WLAN and BT FEMs, or the provision of more than one antenna connected to each of FEM  104 A or  104 B. 
     In some embodiments, the front-end module circuitry  104 , the radio IC circuitry  106 , and baseband processing circuitry  108  may be provided on a single radio card, such as wireless radio card  102 . In some other embodiments, the one or more antennas  101 , the FEM circuitry  104  and the radio IC circuitry  106  may be provided on a single radio card. In some other embodiments, the radio IC circuitry  106  and the baseband processing circuitry  108  may be provided on a single chip or integrated circuit (IC), such as IC  112 . 
     In some embodiments, the wireless radio card  102  may include a WLAN radio card and may be configured for Wi-Fi communications, although the scope of the embodiments is not limited in this respect. In some of these embodiments, the radio architecture  100  may be configured to receive and transmit orthogonal frequency division multiplexed (OFDM) or orthogonal frequency division multiple access (OFDMA) communication signals over a multicarrier communication channel. The OFDM or OFDMA signals may comprise a plurality of orthogonal sub carriers. 
     In some of these multicarrier embodiments, radio architecture  100  may be part of a Wi-Fi communication station (STA) such as a wireless access point (AP), a base station or a mobile device including a Wi-Fi device. In some of these embodiments, radio architecture  100  may be configured to transmit and receive signals in accordance with specific communication standards and/or protocols, such as any of the Institute of Electrical and Electronics Engineers (IEEE) standards including, IEEE 802.11n-2009, IEEE 802.11-2012, IEEE 802.11-2016, IEEE 802.11ac, IEEE 802.11ax, and/or IEEE P802.11be standards and/or proposed specifications for WLANs, although the scope of embodiments is not limited in this respect. Radio architecture  100  may also be suitable to transmit and/or receive communications in accordance with other techniques and standards. 
     In some embodiments, the radio architecture  100  may be configured for high-efficiency (HE) Wi-Fi (HEW) communications in accordance with the IEEE 802.11ax standard. In some embodiments, the radio architecture  100  may be configured for Extremely High Throughput (EHT) communications in accordance with the IEEE 802.11be standard. In these embodiments, the radio architecture  100  may be configured to communicate in accordance with an OFDMA technique, although the scope of the embodiments is not limited in this respect. In some embodiments, the radio architecture  100  may be configured for next generation vehicle-to-everything (NGV) communications in accordance with the IEEE 802.11bd standard and one or more stations including AP  502  may be next generation vehicle-to-everything (NGV) stations (STAs). 
     In some other embodiments, the radio architecture  100  may be configured to transmit and receive signals transmitted using one or more other modulation techniques such as spread spectrum modulation (e.g., direct sequence code division multiple access (DS-CDMA) and/or frequency hopping code division multiple access (FH-CDMA)), time-division multiplexing (TDM) modulation, and/or frequency-division multiplexing (FDM) modulation, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, as further shown in  FIG.  1   , the BT baseband circuitry  108 B may be compliant with a Bluetooth (BT) connectivity standard such as Bluetooth, Bluetooth 4.0 or Bluetooth 5.0, or any other iteration of the Bluetooth Standard. In embodiments that include BT functionality as shown for example in  FIG.  1   , the radio architecture  100  may be configured to establish a BT synchronous connection oriented (SCO) link and/or a BT low energy (BT LE) link. In some of the embodiments that include functionality, the radio architecture  100  may be configured to establish an extended SCO (eSCO) link for BT communications, although the scope of the embodiments is not limited in this respect. In some of these embodiments that include a BT functionality, the radio architecture may be configured to engage in a BT Asynchronous Connection-Less (ACL) communications, although the scope of the embodiments is not limited in this respect. In some embodiments, as shown in  FIG.  1   , the functions of a BT radio card and WLAN radio card may be combined on a single wireless radio card, such as single wireless radio card  102 , although embodiments are not so limited, and include within their scope discrete WLAN and BT radio cards. 
     In some embodiments, the radio-architecture  100  may include other radio cards, such as a cellular radio card configured for cellular (e.g., 3GPP such as LTE, LTE-Advanced or 5G communications). 
     In some IEEE 802.11 embodiments, the radio architecture  100  may be configured for communication over various channel bandwidths including bandwidths having center frequencies of about 900 MHz, 2.4 GHz, 5 GHz, and bandwidths of about 1 MHz, 2 MHz, 2.5 MHz, 4 MHz, 5 MHz, 8 MHz, 10 MHz, 16 MHz, 20 MHz, 40 MHz, 80 MHz (with contiguous bandwidths) or 80+80 MHz (160 MHz) (with non-contiguous bandwidths). In some embodiments, a 320 MHz channel bandwidth may be used. The scope of the embodiments is not limited with respect to the above center frequencies however. 
       FIG.  2    illustrates FEM circuitry  200  in accordance with some embodiments. The FEM circuitry  200  is one example of circuitry that may be suitable for use as the WLAN and/or BT FEM circuitry  104 A/ 104 B ( FIG.  1   ), although other circuitry configurations may also be suitable. 
     In some embodiments, the FEM circuitry  200  may include a TX/RX switch  202  to switch between transmit mode and receive mode operation. The FEM circuitry  200  may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry  200  may include a low-noise amplifier (LNA)  206  to amplify received RF signals  203  and provide the amplified received RF signals  207  as an output (e.g., to the radio IC circuitry  106  ( FIG.  1   )). The transmit signal path of the circuitry  200  may include a power amplifier (PA) to amplify input RF signals  209  (e.g., provided by the radio IC circuitry  106 ), and one or more filters  212 , such as band-pass filters (BPFs), low-pass filters (LPFs) or other types of filters, to generate RF signals  215  for subsequent transmission (e.g., by one or more of the antennas  101  ( FIG.  1   )). 
     In some dual-mode embodiments for Wi-Fi communication, the FEM circuitry  200  may be configured to operate in either the 2.4 GHz frequency spectrum or the 5 GHz frequency spectrum. In these embodiments, the receive signal path of the FEM circuitry  200  may include a receive signal path duplexer  204  to separate the signals from each spectrum as well as provide a separate LNA  206  for each spectrum as shown. In these embodiments, the transmit signal path of the FEM circuitry  200  may also include a power amplifier  210  and a filter  212 , such as a BPF, a LPF or another type of filter for each frequency spectrum and a transmit signal path duplexer  214  to provide the signals of one of the different spectrums onto a single transmit path for subsequent transmission by the one or more of the antennas  101  ( FIG.  1   ). In some embodiments, BT communications may utilize the 2.4 GHZ signal paths and may utilize the same FEM circuitry  200  as the one used for WLAN communications. 
       FIG.  3    illustrates radio IC circuitry  300  in accordance with some embodiments. The radio IC circuitry  300  is one example of circuitry that may be suitable for use as the WLAN or BT radio IC circuitry  106 A/ 106 B ( FIG.  1   ), although other circuitry configurations may also be suitable. 
     In some embodiments, the radio IC circuitry  300  may include a receive signal path and a transmit signal path. The receive signal path of the radio IC circuitry  300  may include at least mixer circuitry  302 , such as, for example, down-conversion mixer circuitry, amplifier circuitry  306  and filter circuitry  308 . The transmit signal path of the radio IC circuitry  300  may include at least filter circuitry  312  and mixer circuitry  314 , such as, for example, up-conversion mixer circuitry. Radio IC circuitry  300  may also include synthesizer circuitry  304  for synthesizing a frequency  305  for use by the mixer circuitry  302  and the mixer circuitry  314 . The mixer circuitry  302  and/or  314  may each, according to some embodiments, be configured to provide direct conversion functionality. The latter type of circuitry presents a much simpler architecture as compared with standard super-heterodyne mixer circuitries, and any flicker noise brought about by the same may be alleviated for example through the use of OFDM modulation.  FIG.  3    illustrates only a simplified version of a radio IC circuitry, and may include, although not shown, embodiments where each of the depicted circuitries may include more than one component. For instance, mixer circuitry  320  and/or  314  may each include one or more mixers, and filter circuitries  308  and/or  312  may each include one or more filters, such as one or more BPFs and/or LPFs according to application needs. For example, when mixer circuitries are of the direct-conversion type, they may each include two or more mixers. 
     In some embodiments, mixer circuitry  302  may be configured to down-convert RF signals  207  received from the FEM circuitry  104  ( FIG.  1   ) based on the synthesized frequency  305  provided by synthesizer circuitry  304 . The amplifier circuitry  306  may be configured to amplify the down-converted signals and the filter circuitry  308  may include a LPF configured to remove unwanted signals from the down-converted signals to generate output baseband signals  307 . Output baseband signals  307  may be provided to the baseband processing circuitry  108  ( FIG.  1   ) for further processing. In some embodiments, the output baseband signals  307  may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry  302  may comprise passive mixers, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  314  may be configured to up-convert input baseband signals  311  based on the synthesized frequency  305  provided by the synthesizer circuitry  304  to generate RF output signals  209  for the FEM circuitry  104 . The baseband signals  311  may be provided by the baseband processing circuitry  108  and may be filtered by filter circuitry  312 . The filter circuitry  312  may include a LPF or a BPF, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  302  and the mixer circuitry  314  may each include two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion respectively with the help of synthesizer  304 . In some embodiments, the mixer circuitry  302  and the mixer circuitry  314  may each include two or more mixers each configured for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry  302  and the mixer circuitry  314  may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, the mixer circuitry  302  and the mixer circuitry  314  may be configured for super-heterodyne operation, although this is not a requirement. 
     Mixer circuitry  302  may comprise, according to one embodiment: quadrature passive mixers (e.g., for the in-phase (I) and quadrature phase (Q) paths). In such an embodiment, RF input signal  207  from  FIG.  3    may be down-converted to provide I and Q baseband output signals to be sent to the baseband processor. 
     Quadrature passive mixers may be driven by zero and ninety-degree time-varying LO switching signals provided by a quadrature circuitry which may be configured to receive a LO frequency (f LO ) from a local oscillator or a synthesizer, such as LO frequency  305  of synthesizer  304  ( FIG.  3   ). In some embodiments, the LO frequency may be the carrier frequency, while in other embodiments, the LO frequency may be a fraction of the carrier frequency (e.g., one-half the carrier frequency, one-third the carrier frequency). In some embodiments, the zero and ninety-degree time-varying switching signals may be generated by the synthesizer, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the LO signals may differ in duty cycle (the percentage of one period in which the LO signal is high) and/or offset (the difference between start points of the period). In some embodiments, the LO signals may have a 25% duty cycle and a 50% offset. In some embodiments, each branch of the mixer circuitry (e.g., the in-phase (I) and quadrature phase (Q) path) may operate at a 25% duty cycle, which may result in a significant reduction is power consumption. 
     The RF input signal  207  ( FIG.  2   ) may comprise a balanced signal, although the scope of the embodiments is not limited in this respect. The I and Q baseband output signals may be provided to low-nose amplifier, such as amplifier circuitry  306  ( FIG.  3   ) or to filter circuitry  308  ( FIG.  3   ). 
     In some embodiments, the output baseband signals  307  and the input baseband signals  311  may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals  307  and the input baseband signals  311  may be digital baseband signals. In these alternate embodiments, the radio IC circuitry may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry. 
     In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, or for other spectrums not mentioned here, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the synthesizer circuitry  304  may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry  304  may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. According to some embodiments, the synthesizer circuitry  304  may include digital synthesizer circuitry. An advantage of using a digital synthesizer circuitry is that, although it may still include some analog components, its footprint may be scaled down much more than the footprint of an analog synthesizer circuitry. In some embodiments, frequency input into synthesizer circuitry  304  may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. A divider control input may further be provided by either the baseband processing circuitry  108  ( FIG.  1   ) or application processor  111  ( FIG.  1   ) depending on the desired output frequency  305 . In some embodiments, a divider control input (e.g., N) may be determined from a look-up table (e.g., within a Wi-Fi card) based on a channel number and a channel center frequency as determined or indicated by application processor  111 . 
     In some embodiments, synthesizer circuitry  304  may be configured to generate a carrier frequency as the output frequency  305 , while in other embodiments, the output frequency  305  may be a fraction of the carrier frequency (e.g., one-half the carrier frequency, one-third the carrier frequency). In some embodiments, the output frequency  305  may be a LO frequency (f LO ). 
       FIG.  4    illustrates a functional block diagram of baseband processing circuitry  400  in accordance with some embodiments. The baseband processing circuitry  400  is one example of circuitry that may be suitable for use as the baseband processing circuitry  108  ( FIG.  1   ), although other circuitry configurations may also be suitable. The baseband processing circuitry  400  may include a receive baseband processor (RX BBP)  402  for processing receive baseband signals  309  provided by the radio IC circuitry  106  ( FIG.  1   ) and a transmit baseband processor (TX BBP)  404  for generating transmit baseband signals  311  for the radio IC circuitry  106 . The baseband processing circuitry  400  may also include control logic  406  for coordinating the operations of the baseband processing circuitry  400 . 
     In some embodiments (e.g., when analog baseband signals are exchanged between the baseband processing circuitry  400  and the radio IC circuitry  106 ), the baseband processing circuitry  400  may include ADC  410  to convert analog baseband signals received from the radio IC circuitry  106  to digital baseband signals for processing by the RX BBP  402 . In these embodiments, the baseband processing circuitry  400  may also include DAC  412  to convert digital baseband signals from the TX BBP  404  to analog baseband signals. 
     In some embodiments that communicate OFDM signals or OFDMA signals, such as through baseband processor  108 A, the transmit baseband processor  404  may be configured to generate OFDM or OFDMA signals as appropriate for transmission by performing an inverse fast Fourier transform (IFFT). The receive baseband processor  402  may be configured to process received OFDM signals or OFDMA signals by performing an FFT. In some embodiments, the receive baseband processor  402  may be configured to detect the presence of an OFDM signal or OFDMA signal by performing an autocorrelation, to detect a preamble, such as a short preamble, and by performing a cross-correlation, to detect a long preamble. The preambles may be part of a predetermined frame structure for Wi-Fi communication. 
     Referring back to  FIG.  1   , in some embodiments, the antennas  101  ( FIG.  1   ) may each 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. Antennas  101  may each include a set of phased-array antennas, although embodiments are not so limited. 
     Although the radio-architecture  100  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. 
       FIG.  5    illustrates a WLAN  500  in accordance with some embodiments. The WLAN  500  may comprise a basis service set (BSS) that may include an access point (AP)  502 , which may be an AP, a plurality of stations  504 , and a plurality of legacy (e.g., IEEE 802.11n/ac/ax) devices  506 . In some embodiments, WLAN  500  may be configured for Extremely High Throughput (EHT) communications in accordance with the IEEE 802.11be standard and one or more stations including AP  502  may be EHT STAs. In some embodiments, WLAN  500  may be configured for next generation vehicle-to-everything (NGV) communications in accordance with the IEEE 802.11bd standard and one or more stations including AP  502  may be next generation vehicle-to-everything (NGV) stations (STAs). 
     The AP  502  may be an AP using the IEEE 802.11 to transmit and receive. The AP  502  may be a base station. The AP  502  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 orthogonal frequency division multiple-access (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 multiple-user multiple-input multiple-output (MU-MIMO). There may be more than one AP  502  that is part of an extended service set (ESS). A controller (not illustrated) may store information that is common to the more than one APs  502 . IEEE P802.11be/D2.0, May 2022 is incorporated herein by reference. 
     The legacy devices  506  may operate in accordance with one or more of IEEE 802.11 a/b/g/n/ac/ad/af/ah/aj/ay, or another legacy wireless communication standard. The legacy devices  506  may be STAs or IEEE STAs. The STAs  504  may be wireless transmit and receive devices such as cellular telephone, portable electronic wireless communication devices, smart 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 STAs  504  may be termed high efficiency (HE) stations. 
     AP  502  may communicate with legacy devices  506  in accordance with legacy IEEE 802.11 communication techniques. In example embodiments, AP  502  may also be configured to communicate with STAs  504  in accordance with legacy IEEE 802.11 communication techniques. 
     In some embodiments, a frame may be configurable to have the same bandwidth as a channel. The frame may be a physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU). In some embodiments, there may be different types of PPDUs that may have different fields and different physical layers and/or different media access control (MAC) layers. 
     The bandwidth of a channel may be 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, the bandwidth of a channel may be 1 MHz, 1.25 MHz, 2.03 MHz, 2.5 MHz, 4.06 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. In some embodiments the bandwidth of the channels may be based on a number of active data subcarriers. In some embodiments the bandwidth of the channels is based on 26, 52, 106, 242, 484, 996, or 2×996 active data subcarriers or tones that are spaced by 20 MHz. In some embodiments the bandwidth of the channels is 256 tones spaced by 20 MHz. In some embodiments the channels are multiple of 26 tones or a multiple of 20 MHz. In some embodiments a 20 MHz channel may comprise 242 active data subcarriers or tones, which may determine the size of a Fast Fourier Transform (FFT). An allocation of a bandwidth or a number of tones or sub-carriers may be termed a resource unit (RU) allocation in accordance with some embodiments. 
     In some embodiments, the 26-subcarrier RU and 52-subcarrier RU are used in the 20 MHz, 40 MHz, 80 MHz, 160 MHz and 80+80 MHz OFDMA PPDU formats. In some embodiments, the 106-subcarrier RU is used in the 20 MHz, 40 MHz, 80 MHz, 160 MHz and 80+80 MHz OFDMA and MU-MIMO PPDU formats. In some embodiments, the 242-subcarrier RU is used in the 40 MHz, 80 MHz, 160 MHz and 80+80 MHz OFDMA and MU-MIMO PPDU formats. In some embodiments, the 484-subcarrier RU is used in the 80 MHz, 160 MHz and 80+80 MHz OFDMA and MU-MIMO PPDU formats. In some embodiments, the 996-subcarrier RU is used in the 160 MHz and 80+80 MHz OFDMA and MU-MIMO PPDU formats. 
     A frame may be configured for transmitting a number of spatial streams, which may be in accordance with MU-MIMO and may be in accordance with OFDMA. In other embodiments, AP  502 , STA  504 , and/or legacy device  506  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 HE and/or EHT communications. In accordance with some IEEE 802.11 embodiments (e.g., IEEE 802.11ax embodiments) a AP  502  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 control period. In some embodiments, the control period may be termed a transmission opportunity (TXOP). AP  502  may transmit a master-sync transmission, which may be a trigger frame or control and schedule transmission, at the beginning of the control period. AP  502  may transmit a time duration of TXOP and sub-channel information. During the control period, STAs  504  may communicate with AP  502  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 control period, the AP  502  may communicate with STAs  504  using one or more frames. During the control period, the STAs  504  may operate on a sub-channel smaller than the operating range of the AP  502 . During the control period, legacy stations refrain from communicating. The legacy stations may need to receive the communication from the AP  502  to defer from communicating. 
     In accordance with some embodiments, during TXOP the STAs  504  may contend for the wireless medium with the legacy devices  506  being excluded from contending for the wireless medium during the master-sync transmission. In some embodiments the trigger frame may indicate an uplink (UL) and/or UL OFDMA TXOP. In some embodiments, the trigger frame may include a DL UL-MU-MIMO and/or DL OFDMA with a schedule indicated in a preamble portion of trigger frame. 
     In some embodiments, the multiple-access technique used during the TXOP 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. In some embodiments, the multiple access technique may be a Code division multiple access (CDMA). 
     The AP  502  may also communicate with legacy stations  506  and/or non-legacy stations  504  in accordance with legacy IEEE 802.11 communication techniques. In some embodiments, the AP  502  may also be configurable to communicate with STAs  504  outside the TXOP in accordance with legacy IEEE 802.11 communication techniques, although this is not a requirement. 
     In some embodiments station  504  may be a “group owner” (GO) for peer-to-peer modes of operation. A wireless device may be a Station  502  or a AP  502 . 
     In some embodiments, the station  504  and/or AP  502  may be configured to operate in accordance with IEEE 802.11mc. In example embodiments, the radio architecture of  FIG.  1    is configured to implement the station  504  and/or the AP  502 . In example embodiments, the front-end module circuitry of  FIG.  2    is configured to implement the station  504  and/or the AP  502 . In example embodiments, the radio IC circuitry of  FIG.  3    is configured to implement the station  504  and/or the AP  502 . In example embodiments, the base-band processing circuitry of  FIG.  4    is configured to implement the station  504  and/or the AP  502 . 
     In example embodiments, the stations  504 , AP  502 , an apparatus of the stations  504 , and/or an apparatus of the AP  502  may include one or more of the following: the radio architecture of  FIG.  1   , the front-end module circuitry of  FIG.  2   , the radio IC circuitry of  FIG.  3   , and/or the base-band processing circuitry of  FIG.  4   . 
     In example embodiments, the radio architecture of  FIG.  1   , the front-end module circuitry of  FIG.  2   , the radio IC circuitry of  FIG.  3   , and/or the base-band processing circuitry of  FIG.  4    may be configured to perform the methods and operations/functions herein. 
     In example embodiments, the station  504  and/or the AP  502  are configured to perform the methods and operations/functions described herein. In example embodiments, an apparatus of the station  504  and/or an apparatus of the AP  502  are configured to perform the methods and functions described herein. The term Wi-Fi may refer to one or more of the IEEE 802.11 communication standards. AP and STA may refer to access point  502  and/or station  504  as well as legacy devices  506 . 
     In some embodiments, a AP STA may refer to a AP  502  and a STAs  504  that is operating a APs  502 . In some embodiments, when an STA  504  is not operating as a AP, it may be referred to as a non-AP STA or non-AP. In some embodiments, STA  504  may be referred to as either a AP STA or a non-AP.
         Although the IEEE 802.11b standard is more than 20 years old, it is still widely used for long range communications in WLANs. However, it has certain downsides, e.g., weak channel coding and the coexistence issue with mainstream OFDM-based systems. There is a need to replace it by an OFDM-based system with similar range coverage, which is about 9 dB better than the existing 20 MHz MCS 0 of OFDM-based 802.11a, the 6 Mbps mode.       

     The high-efficiency (HE) extended range (ER) single user (SU) PPDU format was defined in the IEEE 802.11ax standards. Both the STF and the LTF are boosted with 3 dB and both the HE-SIG-A1 and the HE-SIG-A2 are repeated Twice, which is HE-SIG-A1, HE-SIG-A1-R, HE-SIG-A2 and HE-SIG-A2-R. The HE-SIG-A1-R is modulated with QBPSK to indicate the extended range mode. For the data, the HE ER SU PPDU supports only a single 242-tone or 106-tone RU. An HE ER SU PPDU with a 242-tone RU shall be transmitted with only the MCS 0, 1 and 2 with single spatial stream. An HE ER SU PPDU with a 106-tone RU is transmitted with only the MCSO with single spatial stream and the 106-tone RU allocation within the 20 MHz tone plan is fixed as the one that is higher in the frequency. 
     An ER preamble was also defined in IEEE 802.11be. Both the STF and LTF are boosted with 3 dB, and both the U-SIG1 and the U-SIG2 are repeated twice to improve the performance. The U-SIG-sym-1-R is transmitted with QBPSK, which is used to indicate the extended range mode. However, an ER data format was not introduced in 802.11be. 
     On the other hand, the IEEE 802.11be draft standard for the PHY introduces EHT duplicate (DUP) mode for a single user transmissions with single spatial stream and LDPC coding in the 6 GHz band as EHT MCS 14. However, it is only defined and used for channel bandwidths of 80/160/320 MHz. 
     Unfortunately, the current ER preamble configuration is only able to achieve up to 3 dB performance gain. The actual improved performance is only about 1.5 dB. This is not high enough to achieve symmetric performance between uplink and downlink. Therefore, a new ER preamble, which can achieve about 6 or 9 dB better than the existing 20 MHz MCS 0 of OFDM-based 802.11a, is needed future WLAN standards, such as in Wi-Fi 8. 
     Embodiments disclosed herein provide several different PPDU configurations that can support ER transmission over 40/80/160 even 320 MHz channel and may achieve 6 or 9 dB improvement in performance. 
       FIG.  6    illustrates an extended range (ER) PPDU, in accordance with some embodiments.  FIG.  7    illustrates an ER PPDU, in accordance with some other embodiments. As shown in  FIG.  6   , the ER preamble includes pre-ER modulated fields and ER modulated fields. The ER preamble includes legacy preamble fields  602  and ER preamble fields  606  including L-STF, L-LTF, L-SIG, RL-SIG, U-SIG  604 , ER-STF, ER-LTF and ER-SIG. ER data field  608  may follow the ER-SIG. The ER modulated fields of the ER preamble include ER-STF2  610  and ER-LTF2  612 . The pre-ER modulated fields may be duplicated over each 20 MHz subchannels if the transmission is over a channel wider than 20 MHz. Although the content of the pre-ER modulated fields is the same for each 20 MHz subchannel, the transmitted signals can differ by a global phase and/or a cyclic shift delay (CSD). For Wi-Fi 8, the U-SIG field includes two parts, U-SIG-1 and U-SIG-2, and the total length is two OFDM symbols. The encoding and modulation of U-SIG may be the same as that in 802.11be for MU PPDU and TB PPDU. Each U-SIG field may contain 26 data bits and may be set as shown in following table: 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                 Two parts 
                   
                   
                 Number 
                   
               
               
                 of U-SIG 
                 Bit 
                 field 
                 of bits 
                 Description 
               
               
                   
               
             
            
               
                 U-SIG-1 
                 B0- 
                 PHY  
                 3 
                 Differentiate between  
               
               
                   
                 B2 
                 Version 
                   
                 different PHY clauses: 
               
               
                   
                   
                 identifier 
                   
                 Set to 0 for EHT. 
               
               
                   
                   
                   
                   
                 Set to 1 for UHR. 
               
               
                   
                   
                   
                   
                 Values 2-7 are Validate 
               
               
                   
                 B3- 
                 Bandwidth 
                 3 
                 Set to 0 for 20 MHz. 
               
               
                   
                 B5 
                   
                   
                 Set to 1 for 40 MHz. 
               
               
                   
                   
                   
                   
                 Set to 2 for 80 MHz. 
               
               
                   
                   
                   
                   
                 Set to 3 for 160 MHz. 
               
               
                   
                   
                   
                   
                 Set to 4 for 320 MHz-1. 
               
               
                   
                   
                   
                   
                 Set to 5 for 320 MHz-2. 
               
               
                   
                   
                   
                   
                 See definition of 320 MHz-1  
               
               
                   
                   
                   
                   
                 and 320 MHz-2 in 36.3.23.2  
               
               
                   
                   
                   
                   
                 (Channelization for 320  
               
               
                   
                   
                   
                   
                 MHz channel). 
               
               
                   
                   
                   
                   
                 Values 6 and 7 are Validate. 
               
               
                   
                 B6 
                 Punctured 
                   
                 Indicates whether the PPDU  
               
               
                   
                   
                 Channel 
                   
                 is sent in UL or DL. Set to  
               
               
                   
                   
                 Information 
                   
                 the TXVECTOR parameter  
               
               
                   
                   
                   
                   
                 UPLINK_FLAG. A value of  
               
               
                   
                   
                   
                   
                 1 indicates the PPDU is  
               
               
                   
                   
                   
                   
                 addressed to an AP. A value  
               
               
                   
                   
                   
                   
                 of 0 indicates the PPDU is  
               
               
                   
                   
                   
                   
                 addressed to a non-AP STA. 
               
               
                   
                 B7- 
                 BSS Color 
                 6 
                 An identifier of the BSS. 
               
               
                   
                 B12 
                   
                   
                 Set to the TXVECTOR  
               
               
                   
                   
                   
                   
                 parameter BSS_COLOR. 
               
               
                   
                 B13- 
                 TXOP 
                 7 
                 If the TXVECTOR parameter  
               
               
                   
                 B19 
                   
                   
                 TXOP_DURATION is  
               
               
                   
                   
                   
                   
                 UNSPECIFIED, set to 127 to  
               
               
                   
                   
                   
                   
                 indicate the absence of  
               
               
                   
                   
                   
                   
                 duration information. 
               
               
                   
                   
                   
                   
                 If the TXVECTOR parameter  
               
               
                   
                   
                   
                   
                 TXOP_DURATION is an  
               
               
                   
                   
                   
                   
                 integer value, set to a value  
               
               
                   
                   
                   
                   
                 less than 127 to indicate  
               
               
                   
                   
                   
                   
                 duration information for NAV 
               
               
                   
                   
                   
                   
                 setting and protection of the  
               
               
                   
                   
                   
                   
                 TXOP as follows: 
               
               
                   
                   
                   
                   
                 If the TXVECTOR parameter  
               
               
                   
                   
                   
                   
                 TXOP_DURATION 
               
               
                   
                   
                   
                   
                 is less than 512, set to 2 × 
               
               
                   
                   
                   
                   
                 floor(TXOP_DURATION/8). 
               
               
                   
                   
                   
                   
                 Otherwise, set to 
               
               
                   
                   
                   
                   
                 2 × floor((TXOP_ 
               
               
                   
                   
                   
                   
                 DURATION − 512)/128) + 1. 
               
               
                   
                 B20 
                 ER 
                 1 
                 Indicates whether it is ER  
               
               
                   
                   
                   
                   
                 PPDU or not: 
               
               
                   
                   
                   
                   
                 Set to 0 for non-ER PPDU 
               
               
                   
                   
                   
                   
                 Set to 1 for ER PPDU 
               
               
                   
                 B21- 
                 Disregard 
                 3 
                 Set to all is and treat as  
               
               
                   
                 B24 
                   
                   
                 Disregard 
               
               
                   
                 B25 
                 Validate 
                 1 
                 Set to 1 and treat as Validate 
               
               
                   
               
            
           
         
       
     
     The RL-SIG and the U-SIG with the above setting can be used to differentiate a Wi-Fi 8 UHR ER preamble from a Wi-Fi 7 preamble, Wi-Fi 7 ER preamble and Wi-Fi 8 (non-ER) preamble. The L-STF, L-LTF, L-SIG, RL-SIG and U-SIG of the UHR-ER preamble may not be received by the ER receiver at low RSSI. Therefore, the ER-STF and ER-LTF, which stand for “extend range-STF” and “extended range-LTF”, and are configured to support packet acquisition, fine time/frequency synchronization, channel estimation etc. at low RSSI, are added after the U-SIG. 
     The ER-SIG stands for extended range SIG, which is used to define the modulation/coding and other transmission parameters to decode the following ER-Data. The ER-SIG may be transmitted with MCS 15 or new defined MCS to support ER application, such as MCS 14. Note: MCS 14 was defined for 80/160/320 MHz bandwidth and used in 6 GHz band only in 802.11be but can be extended to 20/40 MHz and used in 2.4 and 5 GHz band. Or MCS 16, which is BPSK+DCM and dup over each 20 MHz subchannel. 
     The ER-SIG fields for a UHR ER PPDU may contain the fields listed in following table, or other fields and more than two ER-SIGs may be needed: 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                 Two 
                   
                   
                   
                   
               
               
                 parts of 
                   
                   
                 Number 
                   
               
               
                 ER-SIG 
                 Bit 
                 field 
                 of bits 
                 Description 
               
               
                   
               
             
            
               
                 ER-SIG-1 
                 B0- 
                 PHY 
                 3 
                 Differentiate between  
               
               
                   
                 B2 
                 Version 
                   
                 different PHY clauses: 
               
               
                   
                   
                 identifier 
                   
                 Set to 0 for EHT. 
               
               
                   
                   
                   
                   
                 Set to 1 for UHR. 
               
               
                   
                   
                   
                   
                 Values 2-7 are Validate 
               
               
                   
                 B3- 
                 Bandwidth 
                 3 
                 Set to 0 for 20 MHz. 
               
               
                   
                 B5 
                   
                   
                 Set to 1 for 40 MHz. 
               
               
                   
                   
                   
                   
                 Set to 2 for 80 MHz. 
               
               
                   
                   
                   
                   
                 Set to 3 for 160 MHz. 
               
               
                   
                   
                   
                   
                 Set to 4 for 320 MHz-1. 
               
               
                   
                   
                   
                   
                 Set to 5 for 320 MHz-2. 
               
               
                   
                   
                   
                   
                 See definition of 320  
               
               
                   
                   
                   
                   
                 MHz-1 and 320 MHz-2 
               
               
                   
                   
                   
                   
                 in 36.3.23.2  
               
               
                   
                   
                   
                   
                 (Channelization for  
               
               
                   
                   
                   
                   
                 320 MHz channel). 
               
               
                   
                   
                   
                   
                 Values 6 and 7 are Validate. 
               
               
                   
                 B6 
                 Punctured 
                   
                 Indicates whether the  
               
               
                   
                   
                 Channel 
                   
                 PPDU is sent in UL or 
               
               
                   
                   
                 Information 
                   
                 DL. Set to the TXVECTOR  
               
               
                   
                   
                   
                   
                 parameter UPLINK_FLAG. 
               
               
                   
                   
                   
                   
                 A value of 1 indicates the  
               
               
                   
                   
                   
                   
                 PPDU is addressed to an AP. 
               
               
                   
                   
                   
                   
                 A value of 0 indicates the  
               
               
                   
                   
                   
                   
                 PPDU is addressed 
               
               
                   
                   
                   
                   
                 to a non-AP STA. 
               
               
                   
                 B7- 
                 BSS Color 
                 6 
                 An identifier of the BSS. 
               
               
                   
                 B12 
                   
                   
                 Set to the TXVECTOR  
               
               
                   
                   
                   
                   
                 parameter BSS_COLOR. 
               
               
                   
                 B13- 
                 TXOP 
                 7 
                 If the TXVECTOR parameter  
               
               
                   
                 B19 
                   
                   
                 TXOP_DURATION is  
               
               
                   
                   
                   
                   
                 UNSPECIFIED, set to 127  
               
               
                   
                   
                   
                   
                 to indicate the absence of  
               
               
                   
                   
                   
                   
                 duration information. 
               
               
                   
                   
                   
                   
                 If the TXVECTOR parameter  
               
               
                   
                   
                   
                   
                 TXOP_DURATION 
               
               
                   
                   
                   
                   
                 is an integer value, set to a  
               
               
                   
                   
                   
                   
                 value less than 127 to indicate  
               
               
                   
                   
                   
                   
                 duration information for  
               
               
                   
                   
                   
                   
                 NAV setting and protection  
               
               
                   
                   
                   
                   
                 of the TXOP as follows: 
               
               
                   
                   
                   
                   
                 If the TXVECTOR parameter  
               
               
                   
                   
                   
                   
                 TXOP_DURATION 
               
               
                   
                   
                   
                   
                 is less than 512, set to 2 × 
               
               
                   
                   
                   
                   
                 floor(TXOP_DURATION/8). 
               
               
                   
                   
                   
                   
                 Otherwise, set to 
               
               
                   
                   
                   
                   
                 2 × floor((TXOP_ 
               
               
                   
                   
                   
                   
                 DURATION − 512)/128) + 1. 
               
               
                   
                 B20 
                 ER 
                 1 
                 Indicates whether it is ER  
               
               
                   
                   
                   
                   
                 PPDU or not: 
               
               
                   
                   
                   
                   
                 Set to 0 for non-ER PPDU 
               
               
                   
                   
                   
                   
                 Set to 1 for ER PPDU 
               
               
                   
                 B21 
                 GI + LTF  
                 1 
                 Indicates the GI duration  
               
               
                   
                   
                 size 
                   
                 and EHT-LTF size: 
               
               
                   
                   
                   
                   
                 Set to 0 to indicate 4x LTF +  
               
               
                   
                   
                   
                   
                 1.6 μs GI. 
               
               
                   
                   
                   
                   
                 Set to 1 to indicate 4x LTF +  
               
               
                   
                   
                   
                   
                 3.2 μs GI. 
               
               
                   
                 B22- 
                 Number of 
                 2 
                 Indicate the number of EHT- 
               
               
                   
                 B23 
                 ER-LTF2 
                   
                 LTF symbols: 
               
               
                   
                   
                 symbols 
                   
                 Set to 0 to indicate 2 EHT- 
               
               
                   
                   
                   
                   
                 LTF symbol. 
               
               
                   
                   
                   
                   
                 Set to 1 to indicate 4 EHT- 
               
               
                   
                   
                   
                   
                 LTF symbols. 
               
               
                   
                   
                   
                   
                 Set to 2 to indicate 6 EHT- 
               
               
                   
                   
                   
                   
                 LTF symbols. 
               
               
                   
                   
                   
                   
                 Set to 3 to indicate 8 EHT- 
               
               
                   
                   
                   
                   
                 LTF symbols. 
               
               
                   
                 B24 
                 Disregard 
                 1 
                 Set to 1 and treat as Disregard 
               
               
                   
                 B25 
                 Validate 
                 1 
                 Set to 1 and treat as Validate 
               
               
                   
               
            
           
         
       
     
     The version bits B 0 -B 2  in ER-SIG1 together with one version dependent bit such as B 20  in ER-SIG1 as shown in above table are used to differentiate a Wi-Fi 8 UHR ER preamble from a Wi-Fi 7 preamble, Wi-Fi 7 ER preamble and Wi-Fi 8 (non-ER) preamble. The GI+LTF size and the number of ER-LTF2 symbols will be indicated in ER-SIG1 or ER-SIG2, and an example is shown in above table. The ER-SIG may also include the spatial reuse, MCS, Length, CRC and Tail field as shown in above table. Potential MCS for ER transmission may include MCSO, 1, 14, 15, or new MCS, such as duplication over each 20 MHz subchannel. 
     For the Wi-Fi 8 UHR STAs, which do not support ER and can detect the legacy preamble  602  (including the RL-SIG and U-SIG), they will parse and classify it as Wi-Fi 8 UHR ER PPDU and set NAV based on the LENGTH in the L-SIG or TXOP in the U-SIG. 
     For the Wi-Fi 8 UHR STAs, which support ER and can detect the legacy preamble  602  (including the RL-SIG and U-SIG), they will parse and classify it as Wi-Fi 8 UHR ER PPDU and switch to the ER-STF, ER-LTF, ER-SIG detection. Based on the decoded bandwidth, GI+LTF size and number of ER-LTF2 symbols information, it will do channel estimation through ER-LTF2 to decode the ER-Data. If ER-Data is not for it, it should/may set NAV based on the length field in L-SIG, or TXOP in U-SIG or length field or TXOP field in ER-SIG. 
     For the Wi-Fi 8 UHR STAB, which support ER, but cannot detect the legacy preamble  602  (including the RL-SIG and U-SIG) due to low RSSI, but can detect the ER preamble  606  (ER-STF, ER-LTF, ER-SIG) will parse and classify it as Wi-Fi 8 UHR ER PPDU after the ER-SIG. If the ER-Data  608  is not for it, it shall/may set NAV based on the length field or TXOP field in the ER-SIG. 
     In the embodiments illustrated in  FIG.  7   , the ER preamble includes legacy preamble fields  602  and ER preamble fields  606  including L-STF, L-LTF, L-SIG, RL-SIG, U-SIG  604 , ER-STF, ER-LTF and ER-SIG. ER data field  608  may follow the ER-SIG. In these embodiments, each preamble field may be duplicated over each 20 MHz subchannels if the transmission is over a channel with bandwidth wider than 20 MHz as shown in  FIG.  7   . The configuration of the U-SIG, ER-STF, ER-LTF and ER-SIG may be the same as that illustrated in  FIG.  6   , however, to decode the ER-Data over wider channel bandwidth, the receiver may need to use the ER-LTFs of the secondary 20 MHz subchannels, and do channel estimation of the secondary 20 MHz subchannels that are loaded with ER-Data after getting the channel bandwidth/puncturing information from the ER-SIG or detecting the active 20 MHz subchannels from the ER-STF or/and ER-LTF. On the other hand, the beamforming can be used starting at the ER-STF. As a result, it cannot be guaranteed that all the nearby ER-receivers refrain from accessing the medium.
         Some embodiments are directed to an ultra-high reliable (UHR) station (STA). In these embodiments, the UHR STA may attempt to decode a physical layer protocol data unit (PPDU) the PPDU received on one or more 20 MHz channels. The PPDU may comprise legacy preamble fields followed by a universal signal field (U-SIG). The U-SIG may indicate via a bit (e.g., bit  20  (B 20 )) whether the PPDU is an extended range (ER) PPDU or a non-ER PPDU. In these embodiments, when the U-SIG indicates that the PPDU is an ER PPDU, the PPDU may also include ER preamble fields following the U-SIG and an ER data field following the ER preamble fields. In these embodiments, when the UHR STA supports ER operations and is able to detect the legacy preamble fields, the UHR STA may classify the PPDU as an ER PPDU based on the legacy preamble fields and the U-SIG and switch to use of the ER preamble fields for decoding the ER data field. In these embodiments, when the UHR STA supports ER operations and is not able to detect the legacy preamble fields (e.g., due to a low received signal strength indication (RSSI), the UHR STA may detect the ER preamble fields, classify the PPDU as an ER PPDU based on the ER preamble fields, and use the ER preamble fields for decoding the ER data field. In these embodiments, the UHR STA may be either a non-AP STA or an AP STA.       

     In some embodiments, when the UHR STA does not support ER operations and is able to detect the legacy preamble fields, the UHR STA may classify the PPDU as an ER PPDU based on the legacy preamble fields and the U-SIG, and set a network allocation vector (NAV) based on one of a length in a legacy signal field (L-SIG) within the legacy preamble fields and a transmission opportunity (TXOP) duration indicated in the U-SIG. 
     In some embodiments, for an ER PPDU, the ER preamble fields comprise pre-ER modulated fields followed by ER modulated fields, the pre-ER modulate fields comprising an ER short training field (ER-STF) followed by an ER long training field (ER-LTF) followed by an ER signal field (ER-SIG), the ER modulated fields comprising the ER data field. In these embodiments, the ER modulated fields may also comprise a second ER short training field (ER-STF2) following the ER-SIG field, the ER-STF2 followed by a second ER long training field (ER-LTF2). In these embodiments, for the UHR STA that supports ER operations and has classified the PPDU as an ER PPDU, the UHR STA may also decode the ER-SIG to determine a bandwidth for the ER-STF2 and the ER LTF2, and the ER data field and perform a channel estimation for the bandwidth using the ER-STF2 and the ER LTF2 fields. The UHR STA may also decode the ER data field over the bandwidth using the channel estimation. 
     In these embodiments, the ER-STF and ER-LTF may be designed to support packet acquisition, fine time/frequency synchronization, channel estimation etc. at low RSSI. The ER-SIG may define the modulation/coding and other transmission parameters used to decode the ER data field that follows. The ER-SIG may be transmitted with a modulation and coding scheme, for example, MCS 14, MCS 15, or MCS 16, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, for an ER PPDU, the ER preamble fields may comprise pre-ER modulated fields followed by ER modulated fields. The pre-ER modulate fields may comprise an ER short training field (ER-STF) followed by an ER long training field (ER-LTF) followed by an ER signal field (ER-SIG). The ER modulated fields may comprise at least the ER data field. In these embodiments, for the UHR STA that supports ER operations and has classified the PPDU as an ER PPDU, the UHR STA may decode the ER-SIG to determine a bandwidth for the ER data field, and perform a channel estimation for the bandwidth using the ER-LTFs for each of the one or more 20 MHz channels of the bandwidth (i.e., since there are no ER-STF2 and the ER LTF2 fields that cover the entire bandwidth). 
     In some embodiments, for an ER PPDU that is transmitted over a wideband channel comprising more than one 20 MHz channel, the pre-ER modulated fields may be duplicated over each 20 MHz channel. In these embodiments, the ER modulated fields and the ER data field may comprise a wideband transmission over the wideband channel. In these embodiments, the UHR STA may decode one or more bits (e.g., bits  0 - 2  (B 0 -B 2 )) of the U-SIG to determine whether the PPDU is configured for an extremely high throughput (EHT) transmission or a UHR transmission. In these embodiments, UHR transmissions may be configured in accordance with a Wi-Fi 8 standard and EHT transmissions may be configured in accordance with a Wi-Fi 7 standard. 
     In some embodiments, for an ER PPDU that is configured for a UHR transmission (i.e., a UHR ER PPDU), the UHR STA may decode a bit (e.g., bit  21  (B 21 )) of the U-SIG to determine a guard interval (GI) duration and a size of the ER-LTF (i.e., the ER-LTF size). In some embodiments, the guard interval duration and the size of the ER-LTF is indicated by the U-SIG to be one of a 4×LTF size with a 1.6 us GI duration and a 4×LTF size with a 3.2 us GI duration. In these embodiments, a longer GI duration may be used when the delay spread of the channel is larger, for example outdoors. 
     In some embodiments, for an ER PPDU that is configured for a UHR transmission (i.e., a UHR ER PPDU), the UHR STA may decode one or more bits (e.g., bits  22 - 23  (B 22 -B 23 )) of the U-SIG to determine a number of symbols in the ER-LTF2 field. In some embodiments, the number of symbols in the ER-LTF2 field indicated by the U-SIG may comprise one of 2, 4, 6 or 8 EHT-LTF symbols. In these embodiments, more EHT-LTF symbols may be used when the RSSI is lower allowing the STA to obtain a better channel state information estimation and an improved time/frequency offset estimation, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the UHR STA may include memory configured to store information decoded from the U-SIG and processing circuitry comprising a baseband processor, although the scope of the embodiments is not limited in this respect. 
     Some embodiments are directed to a UHR STA configured to encode a physical layer protocol data unit (PPDU) for transmission (see  FIGS.  6  and  7   ). The PPDU may comprise legacy preamble fields  602  followed by a universal signal field (U-SIG)  604 . For an extended range (ER) transmission, the UHR STA may encode the U-SIG to indicate via a bit (e.g., bit  20  (B 20 )) whether the PPDU is an ER PPDU or a non-ER PPDU. When the U-SIG is encoded to indicate that the PPDU is an ER PPDU, the UHR STA may further encode the PPDU to include ER preamble fields  606  following the U-SIG and an ER data field  608  following the ER preamble fields. In these embodiments, the ER preamble fields may comprise pre-ER modulated fields followed by ER modulated fields. The pre-ER modulate fields may comprise an ER short training field (ER-STF) followed by an ER long training field (ER-LTF) followed by an ER signal field (ER-SIG). The ER modulated fields may comprise at least the ER data field. In these embodiments, the UHR STA may transmit the encoded PPDU on one or more 20 MHz channels. 
     In these embodiments, the ER-STF and ER-LTF of an ER PPDU may be configured to support packet acquisition, fine time/frequency synchronization, channel estimation, among other things, in low received signal strength situations. 
     In some embodiments, the ER modulated fields may further comprise a second ER short training field (ER-STF2)  610  following the ER-SIG field, the ER-STF2 followed by a second ER long training field (ER-LTF2)  612 . An example of this is illustrated in  FIG.  6   . In these embodiments, the ER-SIG is encoded to indicate the bandwidth for the ER-STF2 and the ER LTF2, and the ER data field. Accordingly, the station receiving the PPDU may use the ER-STF2 and the ER LTF2 fields for performing a channel estimation over the bandwidth which may be used for decoding the ER data field. The bandwidth may comprise one or more 20 MHz channels and may be as great as 320 MHz or even 640 MHz. 
     In some embodiments, for a wideband transmission of an ER PPDU over a wideband channel comprising more than one 20 MHz channel, the UHR STA may be configured to duplicate the pre-ER modulated fields for duplicate transmission over each 20 MHz channel, and configure the ER modulated fields and the ER data field for a wideband transmission over the wideband channel. 
     In some embodiments, the UHR STA may encode the U-SIG via one or more bits (e.g., bits  0 - 2  (B 0 -B 2 )) to indicate whether the PPDU is configured for an extremely high throughput (EHT) transmission or a UHR transmission. For an ER PPDU that is configured for a UHR transmission (i.e., a UHR ER PPDU), the U-SIG may further be encoded to indicate via a bit (e.g., bit  21  (B 21 )) a guard interval (GI) duration and a size of the ER-LTF (i.e., the ER-LTF size). In these embodiments, the guard interval duration and the size of the ER-LTF may be indicated by the U-SIG to be one of a 4×LTF size with a 1.6 us GI duration and a 4×LTF size with a 3.2 us GI duration. 
     In some embodiments, for an ER PPDU that is configured for a UHR transmission (i.e., a UHR ER PPDU), the U-SIG may also be encoded to indicate via one or more bits (e.g., bits  22 - 23  (B 22 -B 23 )) a number of symbols in the ER-LTF2 field. In some embodiments, the number of symbols in the ER-LTF2 field indicated by the U-SIG may comprise one of 2, 4, 6 or 8 EHT-LTF symbols. In these embodiments, a greater number of the EHT-LTF symbols may be included in the ER-LTF2 for a lower received signal strength indication (RSSI), although the scope of the embodiments is not limited in this respect. 
     In some embodiments, when the U-SIG filed indicates that the PPDU is a non-ER PPDU and configured for an EHT transmission or an ER PPDU configured for an EHT transmission, the PPDU may be encoded to include EHT modulated fields comprising EHT preamble fields following the U-SIG filed and an EHT data field following the EHT preamble. In these embodiments, the EHT preamble fields may comprise an EHT signal (EHT-SIG) followed by an EHT short training field (EHT-STF) followed by an EHT long training field (EHT LTF). For a wideband transmission of the EHT PPDU over a wideband channel comprising more than one 20 MHz channel, the UHR STA may configure the EHT modulated fields including the EHT data field a wideband transmission over the wideband channel. 
     In some embodiments, the legacy preamble fields may comprise a non-high throughput (HT) Short Training field (L-STF) followed by a non-HT Long Training field (L-LTF) followed by a non-HT SIGNAL field (L-SIG) followed by a repeated non-HT SIGNAL field (L-SIG). In some embodiments, the non-HT fields may be referred to as legacy fields, although the scope of the embodiments is not limited in this respect. 
     Some embodiments are directed to a method performed by processing circuitry of an ultra-high reliable (UHR) STA. The method may include encoding a physical layer protocol data unit (PPDU) for transmission comprising legacy preamble fields  602  followed by a universal signal field (U-SIG)  604 . For an extended range (ER) transmission, the method may include encoding the U-SIG to indicate whether the PPDU is an ER PPDU or a non-ER PPDU. In these embodiments, when the U-SIG is encoded to indicate that the PPDU is an ER PPDU, the method further comprises further encoding the PPDU to include ER preamble fields  606  following the U-SIG and an ER data field  608  following the ER preamble fields. In these embodiments, the ER preamble fields may comprise pre-ER modulated fields followed by ER modulated fields. The method may also include configuring the UHR STA to transmit the encoded PPDU on one or more 20 MHz channels. 
     In some embodiments, a physical layer protocol data unit may be a physical layer conformance procedure (PLCP) protocol data unit (PPDU). In some embodiments, the AP and STAs may communicate in accordance with one of the IEEE 802.11 standards. IEEE 802.11-2016 is incorporated herein by reference. IEEE P802.11-REVmd/D2.4, August 2019, and IEEE draft specification IEEE P802.11ax/D5.0, October 2019 are incorporated herein by reference in their entireties. In some embodiments, the AP and STAs may be directional multi-gigabit (DMG) STAs or enhanced DMG (EDMG) STAs configured to communicate in accordance with IEEE 802.11ad standard or IEEE draft specification IEEE P802.11ay, February 2019, which is incorporated herein by reference. 
     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.