Transmission of a replicated data sequence with reduced peak-to-average power ratio

Abstract

Describes a transmitted replicated physical layer convergence protocol (PLCP) protocol data unit (PPDU) for a wireless device, the transmission having a reduced peak-to-average power ratio (PAPR). An example includes: obtaining a first sub-PPDU from a PPDU including a data field having data content. A second sub-PPDU can also be obtained by replicating the PPDU including the data content of the PPDU. At least one of phase rotation, phase offset, or phase ramp is applied to at least a portion of a second set of subcarriers of a wideband channel. The first sub-PPDU is transmitted on a first set of subcarriers of the wideband channel, while the second sub-PPDU is transmitted on the second set of subcarriers of the wideband channel.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit and priority of non - provisional patent application No. 17 / 382,263, filed on July 21, 2021, and provisional patent application No. 63 / 055,316, filed on July 22, 2020, with the United States Patent Office. The entire contents of these applications are hereby incorporated by reference in their entirety and for all applicable purposes as if fully set forth herein below. Technical Field

[0003] This disclosure generally relates to wireless communication, and more particularly to replicated data sequences that can achieve a reduced peak - to - average power ratio for communication over a bandwidth channel.

[0004] Description of Related Art

[0005] As wireless communication has evolved towards ever - increasing data rates, the Institute of Electrical and Electronics Engineers (IEEE) has evolved its IEEE 802.11 standard to provide increased throughput. Recently, IEEE 802.11be is being developed, which defines extremely high throughput (EHT) wireless communication using large bandwidth channels (e.g., having a bandwidth of 240 MHz, 320 MHz, or greater). The total channel bandwidth can include a combination of sub - channels (potentially of different sizes) in one or more frequency bands (such as the 5 GHz or 6 GHz bands). The sub - channels (which can be contiguous or non - contiguous within the frequency band) can be collectively referred to as a wireless channel.

[0006] In an IEEE 802.11be - compliant system, a wireless communication device can use orthogonal frequency - division multiple access (OFDMA) to transmit packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). OFDMA is a multi - user version of the orthogonal frequency - division multiplexing (OFDM) digital modulation scheme. OFDM employs multi - carrier modulation, where multiple carriers (such as parallel sub - carriers) each carrying low - bit - rate data are orthogonal to each other. In OFDMA, multi - access is achieved by assigning a subset of sub - carriers to individual users or devices.

[0007] OFDMA transmissions can have high peaks in the time domain because many sub - carrier components are added via an inverse fast Fourier transform (IFFT) operation. Thus, OFDMA transmissions can have a high peak - to - average power ratio (PAPR) compared to single - carrier transmissions. High PAPR is one of the most detrimental aspects in OFDMA systems because it reduces the signal - to - quantization noise ratio (SQNR) of analog - to - digital converters (ADCs) and digital - to - analog converters (DACs), while degrading the efficiency of power amplifiers in the transmitter.

[0008] A replicated packet format (referred to as a "DUPed PPDU") has been proposed for use in low - power indoor (LPI) bands to increase power. In the DUPed PPDU, the EHT modulation part (including the EHT short training field (STF), the EHT long training field (LTF), and data) can be simultaneously replicated and transmitted on two different sub - bands. The replication is performed in the frequency domain, and the signal is transmitted using, for example, 80 MHz, 160 MHz, or 320 MHz channels. The replication in the frequency domain can create periodicity in the time domain, which increases the PAPR of the data part and the EHT - STF part or the EHT - LTF part. The increased PAPR may exceed the allowed signal level, causing difficulties for the receiver and nearby wireless devices.

[0009] Brief overview of some examples

[0010] A brief overview of one or more aspects of the present disclosure is presented below to provide a basic understanding of these aspects. This overview is not an exhaustive survey of all contemplated features of the present disclosure, and is neither intended to identify key or critical elements of all aspects of the present disclosure nor to attempt to define the scope of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in a simplified form as a prelude to the more detailed description that follows.

[0011] In one example, a method for wireless communication by a wireless communication device includes: obtaining a physical layer convergence protocol (PLCP) protocol data unit (PPDU) including a data field having data content; forming a first sub - PPDU including the data content of the PPDU; forming a second sub - PPDU including the data content of the PPDU; transmitting the first sub - PPDU on a first set of sub - carriers of a wideband channel and transmitting the second sub - PPDU on a second set of sub - carriers of the wideband channel; and applying at least one of a phase rotation, a phase offset, or a phase ramp to at least a portion of the second set of sub - carriers before transmission.

[0012] In another example, the PPDU further includes a long training field (LTF) sequence, wherein forming the first sub - PPDU includes forming a first sub - PPDU including the LTF sequence, and forming the second sub - PPDU includes forming a second sub - PPDU including the LTF sequence.

[0013] In another example, applying the phase rotation includes applying the same phase rotation to the data content and the LTF sequence. In another example, the LTF includes an extremely high throughput (EHT) LTF. In another example, the PPDU further includes a long training field (LTF) sequence, and wherein transmitting further includes transmitting the LTF sequence of the PPDU over the wideband channel using subcarriers from both a first set of subcarriers and a second set of subcarriers.

[0014] In another example, applying the phase rotation includes applying the phase rotation to each of the second set of subcarriers. In another example, the PPDU further includes a long training field (LTF) sequence and a short training field (STF) sequence, wherein forming the first sub-PPDU includes forming a first sub-PPDU including the LTF and STF sequences, wherein forming the second sub-PPDU includes forming a second sub-PPDU including the LTF and STF sequences, and wherein applying the phase rotation further includes applying the phase rotation to the LTF and STF sequences.

[0015] In another example, applying the phase rotation includes multiplying the second set of subcarriers by a constant phase rotation factor (-1).

[0016] In another example, applying the phase offset includes applying the phase offset to each of the second set of subcarriers. In another example, the second set of subcarriers is sorted by sequential index, and wherein applying a phase ramp includes applying an additional phase ramp π to each subcarrier in the order of each subcarrier's respective index.

[0017] In another example, applying the phase ramp includes selecting the phase ramp as an equivalent cyclic delay in the time domain of the second set of subcarriers, and wherein the delay is part of the symbol duration of the data content.

[0018] In another example, applying the phase ramp includes selecting the phase ramp by multiplying the index of the corresponding subcarrier k by e to the power of (j2πkτ) / T, where T is the symbol duration of the data symbols of a data sequence (such as the data content), and τ is selected to be less than one percent of T.

[0019] In another example, the first set of subcarriers includes a first sub-band of the wideband channel, wherein the second set of subcarriers includes a second sub-band of the wideband channel, and wherein transmitting the second set of subcarriers includes transmitting using a higher frequency sub-band of the wideband channel than when transmitting the first set of subcarriers.

[0020] In another example, forming the first sub-PPDU includes forming a first sub-PPDU having dual-carrier modulation, and wherein forming the second sub-PPDU includes forming a second sub-PPDU having the same dual-carrier modulation as the first sub-PPDU.

[0021] In another example, transmitting the first sub-PPDU includes transmitting using dual-carrier modulation in a single spatial stream, and wherein transmitting the second sub-PPDU includes transmitting using the dual-carrier modulation in a second single spatial stream.

[0022] In another example, transmitting the first sub-PPDU includes transmitting on at least one of an uplink sub-band and a downlink sub-band of a low-power indoor frequency band.

[0023] In another example, transmitting the first sub-PPDU includes transmitting in an orthogonal frequency-division multiple access (OFDMA) resource unit (RU) having one of the following: 484 subcarriers in a 40 MHz bandwidth are replicated to have 2 RUs of 484 in an 80 MHz bandwidth, 996 subcarriers in an 80 MHz bandwidth are replicated to have 2 RUs of 996 in a 160 MHz bandwidth, or 2x996 subcarriers in a 160 MHz bandwidth are replicated to have 2 RUs of (2x996) in a 320 MHz bandwidth.

[0024] Another example includes modulating the data content of the first sub-PPDU and the data content of the second sub-PPDU using binary phase shift keying before transmission, and wherein transmitting includes transmitting the first sub-PPDU and the second sub-PPDU using dual-carriers in a single spatial stream.

[0025] In another example, a first set of subcarriers includes a first sub-band of the wideband channel, wherein a second set of subcarriers includes a second sub-band of the wideband channel, and wherein the first set of subcarriers is contiguous and does not overlap with the second set of subcarriers.

[0026] Another example includes a third sub-PPDU that forms the data content of the PPDU; and a fourth sub-PPDU that forms the data content of the PPDU including the PPDU; wherein transmitting further includes transmitting the third sub-PPDU on a third set of subcarriers of the wideband channel, and transmitting the fourth sub-PPDU on a fourth set of subcarriers of the wideband channel, the method further including applying at least one of a phase rotation, a phase offset, or a phase ramp to the third set of subcarriers before transmission; and applying at least one of a phase rotation, a phase offset, or a phase ramp to the fourth set of subcarriers before transmission.

[0027] In another example, applying the phase rotation includes multiplying first, second, third, and fourth pluralities of subcarriers by constant phase rotation factors (+1, -1, +1, +1), respectively.

[0028] In another example, applying a phase ramp includes applying a phase ramp to a first subset of a second set of subcarriers and applying a zero phase ramp to a second subset of the second set of subcarriers, the method further including applying a phase ramp to a subset of a first set of subcarriers.

[0029] Another example includes applying different phase rotation factors to the long training field subsequences of respective sub-PPDUs.

[0030] One example for wireless communication by a wireless communication device includes: obtaining a physical layer convergence protocol (PLCP) protocol data unit (PPDU) including a data field having data content; forming a first sub-PPDU including the data content of the PPDU; forming a second sub-PPDU including the data content of the PPDU, wherein the data fields of the first sub-PPDU and the second sub-PPDU are valid data fields of the PPDU and carry the same data content; transmitting the first sub-PPDU on a first RU (2x996) of a broadband channel and transmitting the second sub-PPDU on a second RU (2x996) of the broadband channel, wherein the first sub-PPDU and the second sub-PPDU include the PPDU with DUP; and applying at least one of a phase rotation, a phase offset, or a phase ramp to at least one of the RUs (2x996) before transmission.

[0031] These and other aspects of the present disclosure will be more fully understood after reading the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A block diagram illustrating an example wireless communication network is shown.

[0034] Figure 2A An example protocol data unit (PDU) that can be used for wireless communication between an access point and one or more stations is shown.

[0035] Figure 2B An example legacy signal field (L-SIG) in the PDU of Figure 2A is shown.

[0036] Figure 3A An example physical layer convergence protocol PDU (PPDU) that can be used for wireless communication between an access point and one or more stations is shown.

[0037] Figure 3B Another example PPDU that can be used for wireless communication between an access point and one or more stations is shown.

[0038] Figure 4 An example 2N tone plan is shown.

[0039] Figure 5Shows example modes that can be used for 320 MHz bandwidth transmission and 240 MHz bandwidth transmission.

[0040] Figure 6 Explains an example of orthogonal frequency division multiple access (OFDMA) resource unit (RU) allocation.

[0041] Figure 7 Explains examples of subcarrier spacing and index ranges for various fast Fourier transform (FFT) sizes and symbol durations for 80 MHz, 160 MHz, and 320 MHz transmissions.

[0042] Figure 8A Shows an example replicated PPDU structure, where each sub - PPDU has a different extremely high throughput (EHT) short training field (STF) and EHT long training field (LTF) structure.

[0043] Figure 8B Shows an example replicated PPDU structure, where each sub - PPDU has the same EHT - LTF structure.

[0044] Figure 9 Is a block diagram explaining an example of a wireless communication device that supports replicated PPDUs for communication over a wide - bandwidth channel and can achieve a reduced peak - to - average power ratio.

[0045] Figure 10 Is a flowchart explaining an example method that can be operated at a wireless communication device that supports replicated PPDUs for communication over a wide - bandwidth channel and can achieve a reduced peak - to - average power ratio.

[0046] Figure 11 Is a flowchart explaining an example method that can be operated at a wireless communication device that supports receiving replicated PPDUs for communication over a wide - bandwidth channel.

[0047] Detailed description

[0048] The following description is for certain specific examples and is intended to describe the innovative aspects of the present disclosure. However, those of ordinary skill in the art will readily recognize that the teachings herein can be applied in many different ways. Some or all of the described examples can be in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, IEEE 802.15 standards, as defined by the Bluetooth Special Interest Group (SIG) implemented in any device, system, or network that transmits and receives radio frequency (RF) signals according to one or more of the standards, such as the Long-Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards released by the 3rd Generation Partnership Project (3GPP). The described implementation can be realized in any device, system, or network capable of transmitting and receiving RF signals according to one or more of the following techniques or arts: Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single-Carrier FDMA (SC-FDMA), Single-User (SU) Multiple-Input Multiple-Output (MIMO), and Multi-User (MU) MIMO. The described implementation can also be achieved using other wireless communication protocols or RF signals suitable for use in one or more of Wireless Personal Area Networks (WPANs), Wireless Local Area Networks (WLANs), Wireless Wide Area Networks (WWANs), or Internet of Things (IoT) networks.

[0049] As the IEEE 802.11 standard evolves to use higher bandwidths (such as 320 MHz in IEEE 802.11be), it has been recognized that OFDMA transmissions can have high peaks in the time domain because many subcarrier components are added via the Inverse Fast Fourier Transform (IFFT) operation. Therefore, OFDMA transmissions can have a high Peak-to-Average Power Ratio (PAPR) compared to single-carrier transmissions. The high PAPR of OFDMA transmissions reduces the Signal-to-Quantization Noise Ratio (SQNR) of the Analog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC) in the radio chain and degrades the efficiency of the power amplifier in the transmitter.

[0050] A replicated packet format (referred to as the "DUPed PPDU") has been proposed for use in low-power indoor (LPI) bands to boost power. In the DUPed PPDU, the EHT modulation part (including the EHT Short Training Field (STF), EHT Long Training Field (LTF), and data) can be replicated and transmitted simultaneously on two different subbands. The replication is performed in the frequency domain, and the signal is transmitted using, for example, 80 MHz, 160 MHz, or 320 MHz channels. The replication in the frequency domain can create periodicity in the time domain, thereby increasing the PAPR of the data part and the EHT-STF part or the EHT-LTF part. The increased PAPR may exceed the allowed signal level, causing difficulties for the receiving party and nearby wireless devices.

[0051] Aspects generally relate to reducing an increase in PAPR typically associated with transmission of a duplicated PPDU by modifying the timing or phase of the duplicated PPDU, such as by using phase rotation, phase shift, phase ramp, or a combination of these modifications. Some aspects more particularly relate to obtaining a DUPed PPDU from a PPDU and modifying the DUPed PPDU to reduce PAPR when the PPDU and the DUPed PPDU are transmitted together. The PPDU and the DUPed PPDU may be referred to as "sub PPDUs" that have the same data fields and data content. For example, a first sub PPDU is formed to include the data content of the PPDU, and a second sub PPDU is formed to include the data content of the PPDU. The first sub PPDU is transmitted on a first set of subcarriers of a wideband channel. Prior to transmission, at least one of phase rotation, phase shift, or phase ramp is applied to at least a portion of a second set of subcarriers of the wideband channel. Concurrent with or simultaneous to the transmission of the first sub PPDU, the second sub PPDU is transmitted on the second set of subcarriers of the wideband channel.

[0052] In accordance with another aspect, the PPDU may further include a Long Training Field (LTF) sequence. The first sub PPDU may be formed from the PPDU and include the LTF sequence. The second sub PPDU may be formed from the PPDU and also include the LTF sequence. In one example, applying phase rotation to at least a portion of the second set of subcarriers includes applying the same phase rotation to the data content and the LTF sequence of the second sub PPDU. The LTF may include an Extremely High Throughput (EHT) LTF.

[0053] Certain aspects of the subject matter described in this disclosure may be implemented to achieve one or more of the following potential advantages. In some examples, the techniques described may be used to transmit a DUPed PPDU without exceeding an allowed peak-to-average power ratio level. Transmission of the DUPed PPDU is particularly beneficial for boosting signal power in a Low Power Indoor (LPI) band without causing interference to other users in the same band. This duplicated PPDU approach may allow for unimpeded communication without exceeding indoor power limits, i.e., without exceeding the allowed peak-to-average power ratio level.

[0054] Figure 1FIG. 0 shows a block diagram of an example wireless communication network 100. According to some aspects, wireless communication network 100 may be an example of a wireless local area network (WLAN) (such as a Wi-Fi network) (and will be referred to hereinafter as WLAN 100). For example, WLAN 100 may be a network that implements at least one of the IEEE 802.11 wireless communication protocol standards family (such as the standards defined by the IEEE 802.11-2016 specification or its revisions, including but not limited to 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). WLAN 100 may include numerous wireless communication devices, such as access point (AP) 102 and multiple stations (STA) 104. Although only one AP 102 is shown, WLAN network 100 may also include multiple APs 102.

[0055] Each STA 104 may also be referred to as a mobile station (MS), mobile device, mobile handset, wireless handset, access terminal (AT), user equipment (UE), subscriber station (SS), or subscriber unit, among other examples. STA 104 may represent various devices, such as a mobile phone, personal digital assistant (PDA), other handheld devices, netbook, notebook computer, tablet computer, laptop device, display device (e.g., TV, computer monitor, navigation system, etc.), music or other audio or stereo device, remote control device (“remote control”), printer, kitchen or other household appliance, remote key fob (e.g., for a passive keyless entry and start (PKES) system), and other examples.

[0056] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the corresponding AP 102. Figure 1Additionally shown is an example coverage area 106 of AP 108, which may represent the basic service area (BSA) of WLAN 100. A BSS can be identified to users by a service set identifier (SSID), and can also be identified to other devices by a basic service set identifier (BSSID), which can be the media access control (MAC) address of AP 102. AP 102 periodically broadcasts beacon frames (“beacons”) including the BSSID so that any STA 104 within the wireless range of AP 102 can “associate” or re-associate with AP 102 to establish a corresponding communication link 106 (also hereinafter referred to as a “Wi-Fi link”) with AP 102 or maintain the communication link 106 with AP 102. For example, the beacon may include an identification of the primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with AP 102. AP 102 can provide access to an external network to each STA 104 in the WLAN via the corresponding communication link 106.

[0057] To establish a communication link 106 with AP 102, each STA 104 is configured to perform passive or active scanning operations (“scans”) on frequency channels in one or more frequency bands (e.g., 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform passive scanning, STA 104 listens for beacons transmitted by the corresponding AP 102 at periodic time intervals called target beacon transmission times (TBTTs) (measured in time units (TUs), where one TU can be equal to 1024 microseconds (μs)). To perform active scanning, STA 104 generates probe requests and sequentially transmits these probe requests on each channel to be scanned, and listens for probe responses from AP 102. Each STA 104 can be configured to: identify or select an AP 102 to associate with based on scan information obtained through passive or active scanning, and perform authentication and association operations to establish a communication link 106 with the selected AP 102. AP 102 assigns an association identifier (AID) to STA 104 at the end of the association operation, and AP 102 uses this AID to track STA 104.

[0058] As wireless networks become increasingly common, STA 104 may have the opportunity to choose among many BSSs within the range of the STA or among multiple APs 102 that together form an extended service set (ESS) (including multiple connected BSSs). Extended network stations associated with WLAN 100 can be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such an ESS. Thus, STA 104 can be covered by more than one AP 102 and can be associated with different APs 102 at different times for different transmissions. Additionally, after associating with an AP 102, STA 104 can also be configured to periodically scan its surrounding environment to look for a more suitable AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 can perform a "roaming" scan to look for another AP 102 with more favorable network characteristics (such as a greater received signal strength indicator (RSSI) or reduced traffic load).

[0059] In some cases, STA 104 can form a network without an AP 102 or without other equipment other than STA 104 itself. An example of such a network is an ad hoc network (or wireless ad hoc network). An ad hoc network can alternatively be referred to as a mesh network or a peer-to-peer (P2P) network. In some cases, an ad hoc network can be implemented within a larger wireless network (such as WLAN 100). In such an implementation, while STA 104 may be able to communicate with each other through AP102 using communication link 106, STA 104 can also communicate directly with each other via direct wireless link 110. Additionally, two STAs 104 can communicate via direct communication link 110 regardless of whether the two STAs 104 are associated with and served by the same AP 102. In such an ad hoc system, one or more STAs 104 can assume the role played by an AP 102 in a BSS. Such a STA 104 can be referred to as a group owner (GO) and can coordinate transmissions within the ad hoc network. Examples of direct wireless link 110 include Wi-Fi Direct connections, connections established by using Wi-Fi Tunneled Direct Link Setup (TDLS) links, and other P2P group connections.

[0060] AP 102 and STA 104 can operate and communicate (via the respective communication links 106) according to the IEEE 802.11 family of wireless communication protocol standards, such as the standards defined by the IEEE 802.11-2016 specification or its revisions, including but not limited to 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. These standards define the WLAN radio and baseband protocols for the PHY and media access control (MAC) layers. AP 102 and STA 104 transmit and receive wireless communication (hereinafter also referred to as "Wi-Fi communication") with each other in the form of PHY protocol data units (PPDUs) (or physical layer convergence protocol (PLCP) PPDUs). The AP 102 and STA 104 in the WLAN 100 can transmit PPDUs in the unlicensed spectrum, which can be a part of the spectrum including the bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, 5 GHz band, 60 GHz band, 3.6 GHz band, and 900 MHz band. Some implementations of the AP 102 and STA 104 described herein can also communicate in other bands that support both licensed and unlicensed communication, such as the 6 GHz band. AP 102 and STA 104 can also be configured to communicate on other bands, such as shared licensed bands, where multiple operators may have licenses to operate in one or more of the same or overlapping bands.

[0061] Each band can include multiple sub-bands or frequency channels. For example, PPDUs compliant with the IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard revisions can be transmitted on the 2.4 GHz, 5 GHz, or 6 GHz bands, where each band is divided into multiple 20 MHz channels. Thus, these PPDUs are transmitted on physical channels with a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, PPDUs can be transmitted on physical channels with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0062] Each PPDU is a composite structure that includes a PHY preamble and a payload in the form of a PHY service data unit (PSDU). The information provided in the preamble can be used by the receiving device to decode the subsequent data in the PSDU. In instances where the PPDU is transmitted over a bonded channel, the preamble field can be replicated and transmitted in each of the multiple component channels. The PHY preamble can include both a legacy portion (or “legacy preamble”) and a non-legacy portion (or “non-legacy preamble”). The legacy preamble can be used for packet detection, automatic gain control, and channel estimation, among other uses. The legacy preamble can also generally be used to maintain compatibility with legacy devices. The format, decoding, and information provided in the non-legacy portion of the preamble are based on the specific IEEE 802.11 protocol to be used for transmitting the payload.

[0063] Figure 2A An example protocol data unit (PDU) 200 that can be used for wireless communication between an AP 102 and one or more STAs 104 is shown. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the preamble 202 can include a legacy portion that itself includes a legacy short training field (L-STF) 206 that can consist of two BPSK symbols, a legacy long training field (L-LTF) 208 that can consist of two BPSK symbols, and a legacy signal field (L-SIG) 210 that can consist of two BPSK symbols. The legacy portion of the preamble 202 can be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble 202 can also include a non-legacy portion that includes one or more non-legacy fields 212 that follow an IEEE wireless communication protocol such as IEEE 802.11ac, 802.11ax, 802.11be, or a future wireless communication protocol.

[0064] The L-STF 206 generally enables the receiving device to perform coarse timing and frequency tracking and automatic gain control (AGC). The L-LTF 208 generally enables the receiving device to perform fine timing and frequency tracking and also to perform an initial estimate of the wireless channel. The L-SIG 210 generally enables the receiving device to determine the duration of the PDU and use the determined duration to avoid transmitting over the PDU. For example, the L-STF 206, L-LTF 208, and L-SIG 210 may be modulated according to a binary phase shift keying (BPSK) modulation scheme. The payload 204 may be modulated according to a BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitude modulation (QAM) modulation scheme, or another suitable modulation scheme. The payload 204 may include a PSDU that contains a data field (DATA) 214, which in turn may carry higher layer data in the form of, for example, a media access control (MAC) protocol data unit (MPDU) or an aggregated MPDU (A-MPDU).

[0065] Figure 2B shows an Figure 2A example L-SIG 210 in the PDU 200. The L-SIG 210 includes a data rate field 222, reserved bits 224, a length field 226, parity bits 228, and a tail field 230. The data rate field 222 indicates the data rate (note that the data rate indicated in the data rate field 222 may not be the actual data rate of the data carried in the payload 204). The length field 226 indicates the packet length in, for example, symbols or bytes. The parity bits 228 may be used to detect bit errors. The tail field 230 includes tail bits that may be used by the receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device may use the data rate and length indicated in the data rate field 222 and the length field 226 to determine the packet duration in, for example, microseconds (μs) or other time units.

[0066] Figure 3A shows an example PPDU 300 that may be used for wireless communication between an AP and one or more STAs. The PPDU 300 may be used for SU, OFDMA, or MU-MIMO transmissions. The PPDU 300 may be formatted as a high efficiency (HE) WLAN PPDU according to the IEEE 802.11ax amendment to the IEEE 802.11 wireless communication protocol standard. The PPDU 300 includes a PHY preamble that includes a legacy portion 302 and a non-legacy portion 304. The PPDU 300 may further include a PHY payload 306 (e.g., in the form of a PSDU that includes a data field 324) after the preamble.

[0067] The legacy portion 302 of the preamble includes the L-STF 308, L-LTF 310, and L-SIG 312. The non-legacy portion 304 includes a repetition of the L-SIG (RL-SIG) 314, a first HE signal field (HE-SIG-A) 316, a HE short training field (HE-STF) 320, and one or more HE long training fields (or symbols) (HE-LTF) 322. For OFDMA or MU-MIMO communication, the second portion 304 further includes a second HE signal field (HE-SIG-B) 318 that is encoded separately from the HE-SIG-A 316. The HE-STF 320 can be used for timing and frequency tracking and AGC, and the HE-LTF 322 can be used for more refined channel estimation. Similar to the L-STF 308, L-LTF 310, and L-SIG 312, in instances involving the use of bonded channels, the information in the RL-SIG 314 and HE-SIG-A 316 can be replicated and transmitted in each component 20 MHz channel. In contrast, the content in the HE-SIG-B 318 can be unique for each 20 MHz channel and the target specific STA 104.

[0068] The RL-SIG 314 can indicate to the HE-compliant STA 104 that the PPDU 300 is a HE PPDU. The AP 102 can use the HE-SIG-A 316 to identify multiple STAs 104 and notify the multiple STAs 104 that the AP has scheduled UL or DL resources for them. For example, the HE-SIG-A 316 can include a resource allocation subfield that indicates the resource allocation for the identified STAs 104. The HE-SIG-A 316 can be decoded by each HE-compliant STA 104 served by the AP 102. For MU transmission, the HE-SIG-A 316 further includes information that can be used by each identified STA 104 to decode the associated HE-SIG-B 318. For example, the HE-SIG-A 316 can indicate the frame format (including the location and length of the HE-SIG-B 318), the available channel bandwidth, and the modulation and coding scheme (MCS), among other examples. The HE-SIG-A 316 can also include HE WLAN signaling information that can be used by STAs 104 other than the identified STAs 104.

[0069] The HE-SIG-B 318 can carry STA-dependent scheduling information, such as, for example, an MCS value that is STA-dependent (or "user-dependent") and RU allocation information that is STA-dependent. In the context of DL MU-OFDMA, such information enables the corresponding STA 104 to identify and decode the corresponding resource units (RUs) in the associated data field 324. Each HE-SIG-B 318 includes a common field and at least one STA-dependent field. The common field can indicate the RU allocation for multiple STAs 104 (including RU assignment in the frequency domain), indicate which RUs are allocated for MU-MIMO transmission and which RUs correspond to MU-OFDMA transmission, and the number of users in the allocation and other examples. The common field can be encoded with common bits, CRC bits, and tail bits. The user-dependent field is assigned to a specific STA 104 and can be used to schedule a specific RU and indicate the scheduling to other WLAN devices. Each user-dependent field can include multiple user block fields. Each user block field can include two user fields that contain information for two corresponding STAs to decode their respective RU payloads in the data field 324.

[0070] Figure 3B Another example PPDU 350 that can be used for wireless communication between an AP and one or more STAs is shown. The PPDU 350 can be used for SU, OFDMA, or MU-MIMO transmission. The PPDU 350 can be formatted as an extremely high throughput (EHT) WLAN PPDU according to the IEEE 802.11be amendment to the IEEE 802.11 wireless communication protocol standard, or it can be formatted as a PPDU of any future (post-EHT) version that follows a new wireless communication protocol (following a future IEEE 802.11 wireless communication protocol standard or other wireless communication standards). The PPDU 350 includes a PHY preamble that includes a legacy portion 352 and a non-legacy portion 354. The PPDU 350 can further include a PHY payload 356 (e.g., in the form of a PSDU that includes a data field 374) after the preamble.

[0071] The legacy portion 352 of the preamble includes an L-STF 358, an L-LTF 360, and an L-SIG 362. The non-legacy portion 354 of the preamble includes an RL-SIG 364 and a plurality of wireless communication protocol version-related signal fields following the RL-SIG 364. For example, the non-legacy portion 354 may include a common signal field 366 (referred to herein as "U-SIG 366") and an EHT signal field 368 (referred to herein as "EHT-SIG 368"). One or both of the U-SIG 366 and the EHT-SIG 368 may be configured to carry version-related information for other wireless communication protocol versions other than EHT and carry such version-related information. The non-legacy portion 354 further includes an additional short training field 370 (referred to herein as "EHT-STF 370", but may also be configured to carry version-related information for other wireless communication protocol versions other than EHT and carry such version-related information) and one or more additional long training fields 372 (referred to herein as "EHT-LTF 372", but they may be configured to carry version-related information for other wireless communication protocol versions other than EHT and carry such version-related information). The EHT-STF 370 may be used for timing and frequency tracking and AGC, and the EHT-LTF 372 may be used for finer channel estimation. Similar to the L-STF 358, the L-LTF 360, and the L-SIG 362, in instances involving the use of bonded channels, the information in the U-SIG 366 and the EHT-SIG 368 may be replicated and transmitted in each component 20 MHz channel. In some implementations, the EHT-SIG 368 may additionally or alternatively carry information different from the information carried in the primary 20 MHz channel in one or more non-primary 20 MHz channels.

[0072] The EHT-SIG 368 may include one or more jointly encoded symbols and may be encoded in a block different from the block in which the U-SIG 366 is encoded. The EHT-SIG 368 may be used by the AP to identify multiple STAs 104 and notify the multiple STAs 104 that the AP has scheduled UL or DL resources for them. The EHT-SIG 368 may be decoded by each compatible STA 104 served by the AP 102. The EHT-SIG 368 may generally be used by the receiving device to interpret the bits in the data field 374. For example, the EHT-SIG 368 may include RU allocation information, spatial stream configuration information, and per-user signaling information (such as MCS) and other examples. The EHT-SIG 368 may further include a cyclic redundancy check (CRC) (e.g., 4 bits) and a tail (e.g., 6 bits) that may be used for a binary convolutional code (BCC). In some implementations, the EHT-SIG 368 may include one or more code blocks each containing a CRC and a tail. In some aspects, each code block may be encoded separately.

[0073] The EHT-SIG 368 may carry STA-specific scheduling information, such as, by way of example, user-specific MCS values and user-specific RU allocation information. The EHT-SIG 368 may generally be used by the receiving device to interpret the bits in the data field 374. In the context of DL MU-OFDMA, such information enables the corresponding STA 104 to identify and decode the corresponding RU in the associated data field 374. Each EHT-SIG 368 may include a common field and at least one user-specific field. The common field may indicate the RU distribution for multiple STAs 104, indicate the RU assignment in the frequency domain, indicate which RUs are allocated for MU-MIMO transmission and which RUs correspond to MU-OFDMA transmission, and the number of users in the assignment and other examples. The common field may be encoded with common bits, CRC bits, and tail bits. The user-specific field is assigned to a specific STA 104 and may be used to schedule a specific RU and indicate the scheduling to other WLAN devices. Each user-specific field may include multiple user block fields. Each user block field may include, for example, two user fields that contain information for two corresponding STAs to decode their respective RU payloads.

[0074] The presence of RL-SIG 364 and U-SIG 366 may indicate to an EHT or future version-compliant STA 104 that the PPDU 350 is an EHT PPDU or any future (post-EHT) version of a PPDU that follows a new wireless communication protocol (following a future IEEE 802.11 wireless communication protocol standard). For example, U-SIG 366 may be used by a receiving device to interpret bits in one or more of the EHT-SIG 368 or the data field 374.

[0075] As described above, the AP 102 and the STA 104 may support multi-user (MU) communication; that is, concurrent transmissions from one device to each of multiple devices (e.g., multiple simultaneous downlink (DL) communications from the AP 102 to the respective STAs 104), or concurrent transmissions from multiple devices to a single device (e.g., multiple simultaneous uplink (UL) transmissions from the respective STAs 104 to the AP 102). To support MU transmission, the AP 102 and the STA 104 may utilize multi-user multiple-input multiple-output (MU-MIMO) and multi-user orthogonal frequency division multiple access (MU-OFDMA) techniques.

[0076] In a MU-OFDMA scheme, the available spectrum of a wireless channel may be divided into multiple resource units (RUs), each including multiple frequency subcarriers (also referred to as "tones"). Different RUs may be allocated or assigned by the AP 102 to different STAs 104 at a particular time. The size and distribution of the RUs may be referred to as RU allocation. In some implementations, RUs may be allocated in 2 MHz intervals, and thus, the smallest RU may include 26 tones comprising 24 data tones and 2 pilot tones. Thus, in a 20 MHz channel, up to 9 RUs (such as 2 MHz, 26-tone RUs) may be allocated (since some tones are reserved for other purposes). Similarly, in a 160 MHz channel, up to 72 RUs may be allocated. Larger 52-tone, 106-tone, 242-tone, 484-tone, and 996-tone RUs may also be allocated. Adjacent RUs may be separated by nulled subcarriers (such as the DC subcarrier), for example, to reduce interference between adjacent RUs, reduce receiver DC offset, and avoid transmit center frequency leakage.

[0077] For UL MU transmission, the AP 102 may transmit a trigger frame to initiate and synchronize UL MU-OFDMA or UL MU-MIMO transmissions from multiple STAs 104 to the AP 102. Such a trigger frame may thus enable multiple STAs 104 to concurrently send UL traffic to the AP 102 in time. The trigger frame may address one or more STAs 104 by corresponding association identifiers (AIDs), and one or more resource units (RUs) may be assigned to each AID (and thus to each STA 104), which may be used to send UL traffic to the AP 102. The AP may also specify one or more random access (RA) RUs that unscheduled STAs 104 may contend for.

[0078] Certain aspects of the present disclosure may support allowing the AP 102 to allocate STA 104 transmissions in an optimized manner to improve efficiency. High-efficiency wireless (HEW) stations, stations utilizing 802.11 high-efficiency protocols such as IEEE 802.11ax, and stations using older or legacy 802.11 protocols such as 802.11b may all compete or coordinate with each other when accessing the wireless medium.

[0079] In some implementations, the AP 104 may transmit over the wireless medium according to various DL tone plans for HEW STAs. For example, referring to Figure 1 , the STA 104 may be a HEW STA. In some implementations, a HEW STA may communicate using a symbol duration that is four times that of a legacy STA. Accordingly, each transmitted symbol may be four times as long in duration. In the case of using a longer symbol duration, each individual tone may use a quarter of the bandwidth for transmission. For example, in various implementations, a 1x symbol duration may be 3.2 μs, a 2x symbol duration may be 6.4 μs, and a 4x symbol duration may be 12.8 μs. The AP 104 may transmit messages to the HEW STA 104 based on the communication bandwidth according to one or more tone plans. In some aspects, the AP 102 may be configured to transmit to multiple HEW STAs simultaneously using OFDMA.

[0080] Figure 4Example 2N tone plan 400 is shown. In some implementations, tone plan 400 may correspond in the frequency domain to OFDM tones generated using a 2N-point fast Fourier transform (FFT). Tone plan 400 includes 2N OFDM tones indexed from -N to N-1. Tone plan 400 includes two sets of edge or guard tones 410, two sets of data / pilot tones 420, and a direct current (DC) tone set 430. In some implementations, the edge or guard tones 410 and DC tones 430 may be nulled. In some implementations, tone plan 400 may include another suitable number of pilot tones, or may include pilot tones at other suitable tone positions.

[0081] In some aspects, compared to various IEEE 802.11 protocols, an OFDMA tone plan for transmission using a 4x symbol duration may be provided. For example, the 4x symbol duration may use several symbols that may each be 12.8 μs in duration (different from symbols that may be 3.2 μs in duration in some other IEEE 802.11 protocols).

[0082] In some aspects, compared to various IEEE 802.11 protocols, an OFDMA tone plan for transmission using a 2x symbol duration may be provided. For example, the 2x symbol duration may use several symbols that may each be 6.4 μs in duration (different from symbols that may be 3.2 μs or 12.8 μs in duration in some other IEEE 802.11 protocols).

[0083] In some aspects, the data / pilot tones 420 of transmission 400 may be divided among any number of different users. For example, the data / pilot tones 420 may be divided among one to eight users. To divide the data / pilot tones 420, AP 104 or another device may signal each device to indicate which devices may transmit or receive on which tones (of the data / pilot tones 420) in a particular transmission. Accordingly, a system and method for dividing the data / pilot tones 420 may be desirable, and the division may be based on the tone plan.

[0084] Frequency tuning plans can be selected based on several different characteristics. For example, having a simple frequency tuning plan that can remain consistent across most or all of the bandwidth can be beneficial. For example, OFDMA transmissions can be made at 20, 40, 80, 160, 240, or 320 MHz (or combinations thereof), and it may be desirable to use a frequency tuning plan that can be used for any of these bandwidths. Additionally, the frequency tuning plan can be simple because it uses a smaller number of building block sizes. For example, the frequency tuning plan can include units that can be referred to as resource units (RUs). This unit can be used to assign a specific amount of wireless resources (e.g., bandwidth or specific frequencies) to a specific user. For example, a user can be assigned a bandwidth of several RUs, and the data / pilot frequencies 420 being transmitted can be broken down into several RUs.

[0085] Frequency tuning plans can also be selected based on efficiency. For example, transmissions at different bandwidths (e.g., 20, 40, 80, 160, 240, or 320 MHz or combinations thereof) can have different numbers of frequencies. Reducing the number of remaining frequencies can be beneficial. Additionally, in some implementations, it can be beneficial if the frequency tuning plan is configured to preserve the 20, 40, 80, 160, 240, or 320 MHz boundaries. For example, it may be desirable to have a frequency tuning plan that allows each 20, 40, 80, 160, 240, or 320 MHz portion to be decoded separately from one another, rather than having an allocation that can be located on the boundary between two different 20, 40, 80, 160, 240, or 320 MHz portions of the bandwidth. For example, it can be beneficial to align the interference pattern with the 20, 40, 80, 160, 240, or 320 MHz channels. Additionally, having channel binding (which can also be referred to as preamble puncturing) can be beneficial, which creates a 20 MHz "hole" in the transmission when 20 MHz transmissions and 40 MHz transmissions can be made while transmitting at 80, 160, 240, or 320 MHz. This can allow, for example, legacy packets to be transmitted in this unused portion of the bandwidth. This puncturing can be applied to any transmission (e.g., 20, 40, 80, 160, 240, or 320 MHz transmissions), and can create at least a 20 MHz "hole" in the transmission, regardless of the channel or bandwidth being used. Finally, it can also be advantageous to use a frequency tuning plan that provides a fixed pilot frequency position in various different transmissions (such as in different bandwidths).

[0086] As the data transmission rate requirements increase with the addition of additional devices to the network or additional data to be transmitted over the network, a larger channel bandwidth (e.g., for Orthogonal Frequency Division Multiple Access (OFDMA) transmission) can be introduced. In one example, a tone plan for a total channel bandwidth of 320 MHz can be introduced to assist in increasing the peak system transmission data rate and more efficiently utilize the available channels. For example, since new frequencies are available (e.g., 6 GHz), these new tone plans for larger total channel bandwidths can more efficiently utilize the newly available channels. Additionally, the increased total bandwidth that can be provided by these new tone plans can allow for a better rate-versus-range tradeoff. In this scenario, if a larger total bandwidth is used, the same or similar transmission rates can be used to provide greater coverage. Additionally, the larger total channel bandwidth can also improve the efficiency of the tone plan (e.g., for a specific BW, how many tones can be used for data transmission), and can also increase the number of guard bands. As with any total channel bandwidth being used, different modes can be utilized depending on channel availability. For example, the current 80 MHz channel bandwidth can be divided into 20 MHz, 40 MHz, or 80 MHz modes.

[0087] Figure 5 Example modes 500a - 500d that can be used for 320 MHz bandwidth transmission and 240 MHz bandwidth transmission are shown. These can be some of the bandwidth modes available in IEEE 802.11be. As Figure 5 shown, 320 MHz bandwidth transmission can be carried in at least two different modes as shown in 500a and 500b. Each of modes 500a and 500b can represent a different combination of channel bandwidth (BW) and frequency bands that can be used depending on channel availability (e.g., in a 2.4, 5, or 6 GHz network). In the first mode 500a, 320 MHz transmission can be carried in a single contiguous frequency band with a 320 MHz bandwidth. In the second mode 500b, 320 MHz transmission can be carried in two non-contiguous non-overlapping frequency bands having 160 MHz bandwidth and 80 MHz bandwidth, respectively. As shown, each of these frequency bands is separated by unused sub-bands (SBs). In this context, an unused SB refers to a portion of a frequency band that is not part of a wireless channel.

[0088] Similarly, 240 MHz bandwidth transmissions can be sent in at least two different modes as shown in 500c and 500d. In the third mode 500c, the 240 MHz transmission can be sent in a single contiguous frequency band with a 240 MHz bandwidth. In the fourth mode 500d, the 240 MHz transmission can be sent in two non - contiguous and disjoint frequency bands with 160 MHz bandwidth and 80 MHz bandwidth respectively. As shown, each of these frequency bands is separated by unused sub - bands (SBs). In this context, an unused SB refers to a frequency band portion that is not part of a wireless channel.

[0089] In some implementations, the tone plan can be designed and signal generation can be completed for contiguous frequency bands of 80 MHz, 160 MHz, and 320 MHz bandwidth sizes.

[0090] Each of the modes 500a - 500d can have one or more options for creating a 320 MHz bandwidth transmission or a 240 MHz bandwidth transmission. The first mode 500a can include: (1) a first option with a single 320 MHz tone plan; (2) a second option of duplicating two 160 MHz tone plans, one in each of two PHY 160 MHz sub - channels and separated by an unused SB; and (3) a third option of duplicating four 80 MHz tone plans, one in each of four PHY 80 MHz sub - channels separated by unused SBs. The second mode 500b can include: (1) a first option of using two 160 MHz tone plans, one in each of two PHY 160 MHz sub - channels; and (2) a second option of duplicating four 80 MHz tone plans, one in each of four PHY 80 MHz sub - channels and separated by unused SBs. The third mode 500c can include: (1) a first option with a single 240 MHz tone plan; (2) a second option of one 160 MHz tone plan in one PHY 160 MHz sub - channel and one 80 MHz sub - channel in one PHY 80 MHz sub - channel and separated by an unused SB; and (3) a third option of duplicating three 80 MHz tone plans, one in each of three PHY 80 MHz sub - channels separated by unused SBs.

[0091] Based on these patterns and options, different tone plans can be designed or generated for 80, 160, or 320 MHz bandwidths. The tone plan designs for 80 MHz, 160 MHz, and 320 MHz for the 3-symbol duration option are building blocks. In some implementations, different symbol durations can be used for different frequency bands. For example, for the third option in the 320 MHz band, the 160 MHz band can use the first symbol duration, and the 80 MHz band can use a second symbol duration different from the first symbol duration. In some implementations, the tone plan for the 320 MHz bandwidth can be generated or designed based on building blocks (e.g., the 80 and 160 MHz transmissions discussed herein).

[0092] The different patterns described herein for 320 MHz and 240 MHz channel bandwidths depend on the pattern used and can provide different options for symbol duration and tone spacing.

[0093] Figure 6 An example of OFDMA resource unit (RU) allocation is illustrated. In an OFDMA system 600, multiple client devices (stations) can communicate (transmit or receive) with an access point (AP) simultaneously by sharing the available bandwidth. OFDMA allows subcarriers (also referred to as "tones") in the channel bandwidth to be grouped into smaller portions called "resource units" (RUs). Each RU can consist of a group of tones. In various example implementations, an RU can consist of 26 tones, 52 tones, 106 tones, 242 tones, 484 tones, or 996 tones. That is, an RU can have different sizes depending on the number of tones or subcarriers in the RU, such that for example, RU26 contains 26 tones and RU52 contains 52 tones, and so on. These individual RUs are assigned to different client devices or stations, which allows the access point to serve these client devices or stations simultaneously during uplink and downlink transmissions. In an OFDMA allocation system 600, individual RUs can be assigned to each device communicating over a wireless network, and these RUs do not need to be contiguous.

[0094] Although not illustrated in Figure 6 some RUs can be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, and so on. Other RUs can also carry pilot or reference signals. These pilot or reference signals (e.g., including long training fields or LTFs) are available for a receiving device to perform channel estimation of the corresponding channel, which can enable coherent demodulation / detection of control or data channels within the RU.

[0095] Figure 7Examples of subcarrier spacing and index ranges for various Fast Fourier Transform (FFT) sizes and symbol durations for 80 MHz, 160 MHz, and 320 MHz transmissions are illustrated. Each 802.11 protocol can use a 1x symbol duration. A 1x symbol duration can have a subcarrier spacing of 312.5 kHz. Some 802.11 protocols can also use a 4x symbol duration. A 4x symbol duration can have a subcarrier spacing of 78.125 kHz. Next-generation 802.11 devices and standards can utilize a 1x or 4x symbol duration and can also utilize a 2x symbol duration of 6.4 μs with a subcarrier spacing of 156.25 kHz. Specifically, Figure 7Shows the FFT size for each option (e.g., combination of symbol duration and subcarrier spacing). For example, an 80 MHz channel bandwidth (BW) has 256 subcarriers available at 1x symbol duration and 312.5 kHz spacing (Option 1), 512 subcarriers available at 2x symbol duration and 156.25 kHz spacing (Option 2), and 1024 subcarriers available at 4x symbol duration and 78.125 kHz spacing (Option 3). A 160 MHz channel BW has 512 subcarriers available at 1x symbol duration and 312.5 kHz spacing, 1024 subcarriers available at 2x symbol duration and 156.25 kHz spacing, and 2048 subcarriers available at 4x symbol duration and 78.125 kHz spacing. A 320 MHz channel BW has 1024 subcarriers available at 1x symbol duration and 312.5 kHz spacing, 2048 subcarriers available at 2x symbol duration and 156.25 kHz spacing, and 4096 subcarriers available at 4x symbol duration and 78.125 kHz spacing. In some aspects, 1x and 2x symbol durations may have similar benefits compared to 4x symbol duration. In some aspects, 1x and 2x symbol durations may have lower complexity, latency, and memory requirements due to their corresponding smaller Fast Fourier Transform (FFT) sizes compared to 4x symbol duration which has higher complexity, latency, and memory requirements due to its larger FFT size. 1x and 2x symbol durations each have lower subcarrier planning and cyclic prefix (CP) or guard interval (GI) efficiency compared to 4x symbol duration which has higher subcarrier planning and GI efficiency. Additionally, 1x and 2x symbol durations may not have outdoor support while 4x symbol duration may have outdoor support, although 320 MHz bandwidth is typically used indoors. 1x and 2x symbol durations may require new designs to provide OFDMA support as they cannot be mixed with high-efficiency STAs in DL / UL OFDMA. However, 4x symbol duration can provide OFDMA support as it can be mixed with HE STAs in DL / UL OFDMA. When memory size is not considered, then 4x symbol duration can be a more natural choice for symbol duration. But if the goal is to maintain memory size, then 1x or 2x symbol duration may be considered. For 1x-triggered PPDUs, given a 1.6 μs GI, 50% UL overhead is too high, so 2x symbol duration may be a more likely choice. In some implementations, reduced symbol duration can advantageously result in reduced complexity and reduced memory utilization.

[0096] In one example, a data symbol may have a duration of 4x symbol durations, which is 12.8 μs + GI (Guard Interval). In contrast, LTF symbols may have various multiples of the symbol duration. 1x LTF uses a 1x symbol duration, which is 3.2 μs + GI. 2x LTF uses a 2x symbol duration, which is 6.4 μs + GI. 4x LTF uses a 4x symbol duration, which is 12.8 μs + GI, the same as the data symbol. In 802.11ax, three different GI values are defined: 0.8 μs, 1.6 μs, and 3.2 μs. Each of these three values can be selected based on the PPDU format and channel conditions. The same GI can be applied to the LTF field and the data field. For packets using 1x LTF, either 0.8 μs or 1.6 μs GI can be used depending on the PPDU format. For packets using 2x LTF, either 0.8 μs or 1.6 μs GI can be used depending on the PPDU format. For packets using 4x LTF, either 0.8 μs or 3.2 μs GI can be used depending on the PPDU format or channel conditions.

[0097] Accordingly, in Figure 7 the index ranges of subcarriers for each of these options are shown, which shows that 256 subcarriers have a range of [-128, 127], 512 subcarriers have a range of [-256, 255], 1024 subcarriers have a range of [-512, 511], 2048 subcarriers have a range of [-1024, 1023], and 4096 subcarriers have a range of [-2048, 2047].

[0098] As the IEEE 802.11 standard evolves to use higher bandwidths (such as 320 MHz in IEEE 802.11be), it has been recognized that OFDM transmissions can have high peaks in the time domain because many subcarrier components are added via the Inverse Fast Fourier Transform (IFFT) operation. Therefore, OFDM transmissions can have a high Peak-to-Average Power Ratio (PAPR) compared to single-carrier transmissions. The high PAPR of OFDM and OFDMA transmissions reduces the Signal-to-Quantization Noise Ratio (SQNR) of the Analog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC) in the radio chain, while degrading the efficiency of the power amplifier in the transmitter.

[0099] As used herein, a DUPed or replicated PPDU refers to generating a second frame that replicates the entire original PPDU or at least the data portion. Two or more PPDUs (now referred to as sub-PPDUs) are then simultaneously transmitted on more than one sub-band. The replicated PPDU is particularly useful for boosting power in a low-power indoor (LPI) band without causing interference to other users in the same frequency band. In indoor wireless communication (such as WLAN communication), there may be other users in the same frequency band nearby, and there may also be radio obstacles such as walls, wires, pipes, and other fixtures. As a result, despite the short distance between the AP and the STA, or between the STAs in Wi-Fi Direct, data communication may be blocked. The replicated PPDU approach can overcome these difficulties and allow for smooth communication without exceeding the indoor power limit.

[0100] Figure 8A An example of a replicated PPDU 800 is shown, which can be used for 2X DUPed wireless communication between an AP and one or more STAs or between the STAs in the case of Wi-Fi Direct. This PPDU is applicable to both uplink and downlink transmissions between the AP and the STA. The DUPed PPDU 800 is designed to be used in conjunction with transmissions using MCS0 (modulation and coding stream 0, defined as binary phase shift keying (BPSK)) with a single spatial stream (1ss). However, the DUPed PPDU can be applied to many other transmission scenarios in other contexts. The DUPed PPDU 800 can be formatted as an extremely high throughput (EHT) WLAN PPDU according to the IEEE 802.11be amendment to the IEEE 802.11 wireless communication protocol standard, or it can be formatted as a DUPed PPDU in any future (post-EHT) version that follows a new wireless communication protocol (following a future IEEE 802.11 wireless communication protocol standard or other wireless communication standards). The DUPed PPDU 800 includes two frames 836. The first frame can be referred to as the first sub-PPDU 832 and the second frame can be referred to as the second sub-PPDU 834. These two frames are identical and are formed based on the original input PPDU, or the second frame can simply be a copy of the first frame.

[0101] The components or elements of the PPDU 800 are shown as being the same as or similar to those of Figure 3B and can be modified and configured as described in reference to that description. Each sub-PPDU 832, 834 includes a PHY preamble that includes a legacy portion 802 and a non-legacy portion 804, followed by a PHY payload 806 after the preamble, for example, in the form of a PSDU that includes a data field 824.

[0102] The legacy portion 802 of the preamble includes the L-STF 808, the L-LTF 810, and the L-SIG 802. The non-legacy portion 804 of the preamble includes the RL-SIG 804, followed by the U-SIG 816 and the EHT-SIG 818. The non-legacy portion 804 further includes additional EHT-STF 820 and EHT-LTF 822. These fields carry the signals and information as described above for these fields. The second sub-PPDU carries the same fields in the same order. In some aspects, the training, signals, and data are all replicated.

[0103] In some aspects, the legacy portion 802 is transmitted using a legacy MCS (such as MCS0) and 1ss. The non-legacy portion can be transmitted using a higher MCS level and a higher data rate. In some aspects, the DUPed PPDU is also transmitted using MCS0 and 1ss and DCM (dual carrier modulation) such that the entire frame of the two sub-PPDUs 832, 834 is modulated and transmitted in the same manner. Dual carrier modulation can be used to transmit each sub-PPDU 832, 834 modulated on its own carrier.

[0104] Figure 8B A replacement DUPed PPDU 850 is shown where a portion of the non-legacy training 870, 872 is transmitted over the full broadband channel bandwidth, which is different from the legacy portion 852 and different from the data portion 874. The sequence is selected based on the full broadband channel bandwidth. The replacement DUPed PPDU 850 includes two frames 886. The first frame can be referred to as the first sub-PPDU 882 and the second frame can be referred to as the second sub-PPDU 884. These two frames are substantially the same and are formed based on the original input PPDU, or the second frame can simply be made as a copy of the first frame.

[0105] The components or elements of the DUPed PPDU 850, other than a portion of the non-legacy training 870, 872, are the same as Figure 8AThose that are the same or similar therein and can be modified and configured as described with reference to that description. Each sub-PPDU 882, 884 includes a PHY preamble that includes a legacy portion 852 and a non-legacy portion 854, followed by a PHY payload 856 after the preamble. The legacy portion 852 of the preamble includes an L-STF 858, an L-LTF 860, and an L-SIG 862. The non-legacy portion 854 of the preamble includes an RL-SIG 864, a U-SIG 866, and an EHT-SIG 868. The second sub-PPDU 884 carries the same fields and data in the same order. In some aspects, the training, signals, and data are all replicated. The non-legacy portion 854 further includes an EHT-STF 870 and an EHT-LTF 872. These fields are not replicated but are transmitted using the entire bandwidth of the first and second sub-PPDUs.

[0106] In some aspects, the symbol sequences of the EHT-STF 820 and the EHT-LTF 822 are selected to minimize the PAPR. When such sequences are replicated and transmitted simultaneously in two different sub-PPDUs 832, 834 as shown in Figure 8A the replication may result in an increase in the PAPR. This can be addressed by selecting different symbol sequences or by using phase rotation, phase offset, and phase ramps described herein. Alternatively, by transmitting at least some of the training fields of the non-legacy portion 854 using a full-bandwidth channel, the PAPR of the training symbol sequence is not affected. Although only the EHT-STF 870 and the EHT-LTF 872 are shown as stretching across two subbands and two frames 882, 884, the same modification can be applied to any or both of the other fields in the non-legacy portion 850 of the DUPed PPDU 854. The sequence in each STF and LTF is based on the bandwidth to be used. The STF and LTF sequences are defined based on the transmission bandwidth. The sequence designed for the sub-PPDU bandwidth is a different sequence from the sequence designed for the wideband channel bandwidth.

[0107] Three bandwidth concepts are described herein with respect to the use of the DUPed PPDU: the sub-PPDU bandwidth, the total bandwidth (sometimes referred to as the wideband channel), and the subband bandwidth. As used herein, the sub-PPDU bandwidth is directly linked to the bandwidth of a particular sub-PPDU. As used herein, the wideband channel is the total transmission bandwidth of the DUPed PPDUs of all sub-PPDUs. This can be described as the sub-PPDU bandwidth determined by the replication order. For a replication order of 2 where there are 2 sub-PPDUs, the wideband channel is twice the sub-PPDU bandwidth.

[0108] The sub - band bandwidth as used herein is selected based on the communication system requirements of a particular link. It is not necessarily linked to the sub - PPDU bandwidth or the wide - band channel. In some aspects, the wide - band channel may be divisible by the sub - band bandwidth.

[0109] In one transmission example, the DUPed PPDU is selected to have a sub - PPDU size equal to an RU (2x996) and a duplication order of two (2). One RU (2x996) occupies 160 MHz of bandwidth, so the sub - PPDU bandwidth is 160 MHz. Applying a duplication order of 2 gives a 320 - MHz wide - band channel to transmit the DUPed PPDU. In some aspects, the sub - band bandwidth is selected to be 160 MHz, which is equal to the single sub - PPDU bandwidth. In this case, there are only two sub - bands, and each sub - PPDU will be transmitted on a single sub - band.

[0110] In another transmission example, a sub - band bandwidth of 80 MHz is used. In this case, for a total bandwidth of 320 MHz, 4 sub - bands are used, each with a bandwidth of 80 MHz. Each 160 - MHz sub - PPDU is transmitted on two adjacent 80 - MHz sub - bands. The sub - bands are grouped as follows: [sub - band 1, sub - band 2] for sub - PPDU1 and [sub - band 3, sub - band 4] for sub - PPDU2.

[0111] In a third transmission example, a sub - band bandwidth of 40 MHz is used for the same two 160 - MHz sub - PPDUs. For a total bandwidth of 320 MHz, a total of eight (8) sub - bands are used, each with a bandwidth of 40 MHz. Sub - bands 1 - 4 are used for the transmission of one sub - PPDU, and sub - bands 5 - 8 are used for the transmission of the other sub - PPDU.

[0112] In a fourth transmission example, a sub - band bandwidth of 64 MHz is used. In this case, for a total bandwidth of 320 MHz, there are a total of 5 sub - bands, each with a bandwidth of 64 MHz. Sub - PPDU1 is transmitted on sub - bands 1, 2, and half of sub - band 3; sub - PPDU2 is transmitted on the other half of sub - band 3, sub - band 4, and sub - band 5. In this case, one sub - band (sub - band 3) spans across two sub - PPDUs. The allocation of sub - bands can be provided in other variations.

[0113] The sub - PPDU bandwidth and the total bandwidth (wide - band channel) can be selected using the available transmission bandwidth and the desired duplication order. The duplication order can be selected based on the quality of the available radio channels. The sub - band bandwidth is selected independently based on various factors such as the PAPR value, ease of implementation, continuity requirements, etc.

[0114] The sub-PPDU can be considered to be transmitted on one or more sub-bands. From this perspective, the first sub-PPDU is transmitted on the first set of N sub-bands of the wideband channel, while the second sub-PPDU is transmitted on the second set of N sub-bands of the same wideband channel. These two sets of N or 2N sub-bands do not overlap, have equal sub-band bandwidths, and are transmitted together. In other words, the wideband channel is divided into 2N sub-bands that are evenly distributed to each sub-PPDU, and PAPR reduction techniques are applied to the sub-bands.

[0115] In both of these options, the phase modification technique is applied to one or more sub-PPDUs by applying the phase modification technique to the subcarriers carrying a particular sub-PPDU. Although in some transmissions each sub-PPDU includes the same integer number of sub-bands, this is not required. In other transmissions, the subcarriers of the sub-bands are split between one or more sub-PPDUs. For example, 2 sub-PPDUs on a wideband channel divided into 5 sub-bands can be transmitted by splitting one of the sub-bands between the two sub-PPDUs.

[0116] As described above, in some aspects, there may be a possible separation between the sub-PPDU and the sub-band and between the use of subcarriers in a particular sub-band. Even within the same sub-band and for the same sub-PPDU, different processing can be applied to different subcarriers. This technique provides the possibility of applying different processing to the subcarriers within a sub-PPDU. Consider an example where there are a total of 20 subcarriers, and the first 10 subcarriers 1-10 are used to transmit sub-PPDU 1, while the last 10 subcarriers 11-20 are used to transmit sub-PPDU2. In some aspects, some of the subcarriers in the first set of subcarriers, such as subcarriers 1-5, are unchanged. Other subcarriers in the first set of subcarriers, such as subcarriers 6-10, have a phase ramp of π / 3 applied. A phase ramp value of π is applied to a portion of the second set of subcarriers, such as subcarriers 11-15. The remaining portion of the second set of subcarriers has no phase modification. This is just an example of such a scenario. While the replicated PPDU or sub-PPDU is assigned to a particular set of subcarriers and can be assigned to contiguous non-overlapping subcarriers. The phase modification can be distributed partially or fully to subcarriers in different combinations to reduce the PAPR.

[0117] For a DUPed PPDU, the transmission can use a regular sub-band distribution as a building block for replication, such as 40, 80, and 160 MHz. When replicated at order 2, these bandwidths will become the replicated bandwidths of 80, 160, and 320 MHz. In other words, 2 copies of a 40 MHz RU (484) require 80 MHz. The first sub-PPDU is transmitted in an Orthogonal Frequency Division Multiple Access (OFDMA) Resource Unit (RU) with one of the standard sub-band provisions. One RU has 484 sub-carriers in a 40 MHz bandwidth and is replicated to have 2 RUs484 in an 80 MHz bandwidth. RU996 has 996 sub-carriers in an 80 MHz bandwidth and is replicated to have 2 RUs996 in a 160 MHz bandwidth. The RU (2x996) in a 160 MHz bandwidth is replicated to have 2 RUs (2x996) in a 320 MHz bandwidth. This division accommodates existing channel allocations but can be appropriately modified according to specific channel conditions. In addition, the specific number of symbols and bandwidth can be modified to accommodate other implementations. Several different phase modification techniques can be applied to the sub-carriers carrying the DUPed PPDU. In some aspects, a simple phase rotation is applied to the data in a given sub-band. This can be expressed as [a(1)*sub-band 1, …, a(N)*sub-band N], where there are a total of N sub-bands. In a further aspect, the same phase rotation is given to the LTF and data in a given sub-PPDU. In this example, for each of the N sub-bands, the sub-bands are indicated by indices 1 to N. The phase rotation factor a(1) indicates the phase rotation factor that can be selected to reduce the PAPR. This phase rotation factor can be selected as +1 or -1.

[0118] In the example of a 2x replicated PPDU, such as for 2x(RU484) or 2x(RU996), a phase rotation of -1 can be applied to the upper sub-band and no rotation can be applied to the lower sub-band. In the example of a 320 MHz DUPed PPDU, the PPDU that can be expressed as 2x(RU2x996) can apply a (+1 / -1) phase rotation. In some implementations, the wideband channel bandwidth is divided into 4 sub-bands, and the optimal set of coefficients can be given by (+1, -1, +1, +1).

[0119] Although a DUPed PPDU may increase the median PAPR of the data field by up to more than 2 dB even with MCS0 and a single spatial stream, this can be reduced in the case of phase modification to completely eliminate the increase in PAPR. A simple phase rotation of ±1 is efficient for a replicated wideband channel of 320 MHz.

[0120] In a further aspect, the phase modification is a phase ramp and a phase offset applied to each group of subcarriers. The group of subcarriers can be all the subcarriers in a subband or a subset of these subcarriers, and different modifications can be applied to different subsets. In one aspect, a multiplier is applied to the subcarriers, where T is the symbol duration. The phase ramp and the offset e jθ can be applied to each element (the k-th subcarrier) in a subband or any other group of subcarriers; for different subsequences (subbands), the phase ramp and the offset may be different, i.e., {(τ1,θ1),((τ2,θ2),…(τ N ,θ N )}.

[0121] As an example, there is no phase offset such that θ i ≡0. In addition, there is no phase ramp in the lower half of the PPDU bandwidth, i.e., t1 = 0. A π phase ramp (i.e., ) can be applied to the upper half of the PPDU bandwidth, which is equivalent to multiplying the odd-indexed tones by (-1). In another example, instead of a π phase ramp, a small phase ramp is used in the upper half of the PPDU bandwidth. The PAPR can be optimized by choosing t2 between -30 ns and 30 ns. This small phase ramp allows the phase to be modified without changing the receiver. A large phase ramp may require the receiver to receive a signal indicating the size of the ramp.

[0122] Examples of the phase ramps for different subbands are indicated in the following table. The values in the table apply only to the upper half of the PPDU bandwidth.

[0123]

[0124]

[0125] Table

[0126] For the STF and the LTF, the same phase modification can be used or additional phase rotation can be used in some aspects. Alternatively, the STF and the LTF can use the entire wideband channel and additional phase rotation can be applied. In some implementations, the wideband STF and LTF have a lower PAPR than when the STF and LTF are replicated.

[0127] Figure 9FIG. is a block diagram illustrating an example of a wireless communication device that explains a training field that supports communication on a large bandwidth channel and can achieve a reduced peak-to-average power ratio. The wireless communication device 900 can be, for example, an access point or a user station, and can be implemented with a processing system 914 that includes one or more processors 904. Examples of the processor 904 include a microprocessor, a microcontroller, a digital signal processor (DSP), a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. In various examples, the wireless communication device 900 can be configured to perform any one or more of the functions described herein. That is, the processor 900 utilized in the wireless communication device 904 can be used to implement any one or more of the processes and procedures further illustrated in the Figure 10 flowcharts to be discussed later.

[0128] In this example, the processing system 914 can be implemented with a bus architecture generally represented by the bus 902. Depending on the specific application and overall design constraints of the processing system 902, the bus 914 can include any number of interconnected buses and bridges. The bus 902 communicatively couples various circuits including one or more processors (generally represented by the processor 904), the memory 905, and the computer-readable medium (generally represented by the computer-readable medium 906). The bus 902 can also link various other circuits such as a timing source, peripherals, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface 908 provides an interface between the bus 902 and the wireless transceiver 910 (including a transmitter and a receiver). The wireless transceiver 910 provides a communication interface or means for communicating with various other devices over a transmission medium. For example, the wireless transceiver 910 can use one or more antennas 916 and communicate with one or more wireless communication devices according to the IEEE 802.11 protocol (such as IEEE 802.11be). In one implementation, the wireless transceiver 914 can have multiple MCS modes (such as BPSK and higher order QAM modes) and multiple spatial stream modes (such as single spatial stream and multiple input multiple output (MIMO) modes).

[0129] The processor 904 is responsible for managing the bus 902 and general processing, including the execution of software stored on the computer-readable medium 906. The software, when executed by the processor 904, causes the processing system 914 to perform the various functions described below for any particular device. The computer-readable medium 906 and the memory 905 can also be used to store data manipulated by the processor 904 when executing the software.

[0130] In one or more examples, the processor 904 may include a PPDU acquisition circuit 940, a sub-PPDU formation circuit 942, and a phase modification circuit 944. In one example, the PPDU acquisition circuit 940 may be used to acquire a PPDU from a coupled device, buffer, or memory for transmission to another STA or AP. The sub-PPDU generation circuit 942 may be used to duplicate the PPDU or portions thereof (such as the payload) to form two or more sub-PPDUs. The phase modification circuit 944 may be used to modify the phase of the subcarriers of one or more sub-PPDUs using, for example, phase rotation, phase offset, or phase ramp.

[0131] One or more processors 904 in the processing system may execute software. Software should be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether described in software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium 906. The computer-readable medium 906 may be a non-transitory computer-readable medium. As an example, non-transitory computer-readable media include magnetic storage devices (e.g., hard disks, floppy disks, magnetic tape), optical disks (e.g., compact disc (CD) or digital versatile disc (DVD)), smart cards, flash memory devices (e.g., cards, sticks, or key drives), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, removable disks, and any other suitable medium for storing software or instructions that can be accessed and read by a computer. The computer-readable medium 906 may reside within the processing system 914, outside the processing system 914, or be distributed across multiple entities including the processing system 914. The computer-readable medium 906 may be embodied in a computer program product. As an example, the computer program product may include the computer-readable medium in a package material. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0132] In one or more examples, the computer-readable storage medium 906 may include PPDU acquisition instructions 950, sub-PPDU formation instructions 952, and phase modification instructions 954. Of course, in the above example, the circuitry included in the processor 904 is provided merely as an example, and within various aspects of the present disclosure, other devices for performing the described functions may be included, including but not limited to instructions stored in the computer-readable storage medium 906, or any other suitable equipment or device described in any of the processes or algorithms described herein.

[0133] Figure 10 FIG. 1000 is a flow diagram illustrating an example method 1000 that may operate at a wireless communication device that supports replicated PPDUs that can achieve a reduced peak-to-average power ratio for communication over a bandwidth channel. At block 1002, a physical layer convergence protocol (PLCP) protocol data unit (PPDU) is obtained that includes a data field having data content. The PPDU may include legacy and non-legacy fields. As used herein, the terms “obtain” and “acquire” may refer to generate, present, form, construct, retrieve, or receive. At block 1004, a first sub-PPDU is formed that includes the data content of the obtained PPDU. At block 1006, a second PPDU is formed that also includes the data content of the obtained PPDU. The sub-PPDUs are replicated PPDUs, and although they contain data content, there may be differences in the training and signal portions of the sub-PPDUs.

[0134] In some aspects, the data fields of the sub-PPDUs may be defined with specific characteristics. First, for example, it is within a valid PPDU data field and is itself a valid PPDU data field. Second, it may be the content that together forms the DUPed PPDU. Third, all sub-PPDUs of the DUPed PPDU carry the same information in the data payload. Although there are only two sub-PPDUs in this example, there may be four, eight, or any other suitable number of sub-PPDUs to construct the DUPed PPDU.

[0135] At block 1008, phase modification is applied to a second set of subcarriers. The phase modification includes one or more of phase rotation, phase offset, or phase ramp, as described above. Although named as the second set here, the phase modification may alternatively be applied to the first set and the phase modification is not necessarily applied to every subcarrier of the corresponding set. At block 1010, the first sub-PPDU is transmitted on a first set of subcarriers or tones of the wideband channel, while the second sub-PPDU is transmitted on a second set of subcarriers or tones of the wideband channel.

[0136] According to one aspect, the PPDU has a Long Training Field (LTF) sequence, and forming a first sub-PPDU includes forming a first sub-PPDU that includes the LTF sequence. Forming a second sub-PPDU may also include forming a second sub-PPDU that includes the LTF sequence. The two sub-PPDUs have the same LTF sequence and are transmitted together with that sequence. The LTF sequence may be an EHT-LTF sequence or a future training type, as discussed above. Phase modification (such as phase rotation) may also be applied to the LTF sequence or only to the data content.

[0137] According to another aspect, the PPDU has an LTF sequence, and transmitting further includes transmitting the LTF sequence of the PPDU on the wideband channel using subcarriers from both a first set of subcarriers and a second set of subcarriers.

[0138] Figure 11 is an example method 1100 of a flowchart that illustrates operations that can be performed at a wireless communication device that supports receiving Figure 10 a transmitted replicated PPDU. Figure 10 and 11 The wireless communication device of can be an AP or an STA. At block 1102, a replicated sub-PPDU is received on a first and a second set of subcarriers, and at least one of phase rotation, phase offset, or phase ramp has been applied to at least some of the subcarriers. Depending on the implementation, there may be more than two sub-PPDUs, such as 4 or 8 or any other suitable number. The sub-PPDUs all carry the same data content.

[0139] At block 1104, the data content of the first sub-PPDU is demodulated, and at block 1106, the data content of the second sub-PPDU is demodulated. Any additional sub-PPDUs may also be demodulated. In the example described, the sub-PPDUs are demodulated from BPSK and received in a single spatial stream, but other modulation schemes may be used instead.

[0140] At block 1108, the sub-PPDUs are combined to determine the data content carried in two or all of the sub-PPDUs. In the case where a payload is received, the payload is forwarded to the data consumer addressed by the payload.

[0141] Aspect 1: A method for wireless communication by a wireless communication device, comprising: obtaining a first sub-PPDU from a Physical Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) comprising a data field having data content; obtaining a second sub-PPDU by duplicating the PPDU comprising the data content of the PPDU; applying at least one of a phase rotation, a phase offset, or a phase ramp to at least a portion of a second set of subcarriers; and transmitting the first sub-PPDU on a first set of subcarriers of a wideband channel and transmitting the second sub-PPDU on the second set of subcarriers of the wideband channel simultaneously.

[0142] Aspect 2: The method according to aspect 1, wherein the PPDU further comprises a Long Training Field (LTF) sequence, and wherein obtaining the first sub-PPDU comprises obtaining the first sub-PPDU comprising the LTF sequence, and obtaining the second sub-PPDU comprises obtaining the second sub-PPDU comprising the LTF sequence.

[0143] Aspect 3: The method according to any one of aspects 1 or 2, wherein applying the phase rotation comprises applying the same phase rotation to the data content and the LTF sequence.

[0144] Aspect 4: The method according to any one of aspects 2 or 3, wherein the LTF comprises an Extremely High Throughput (EHT) LTF.

[0145] Aspect 5: The method according to aspect 1, wherein the PPDU further comprises a Long Training Field (LTF) sequence, and wherein transmitting further comprises transmitting the LTF sequence of the PPDU on the wideband channel using subcarriers from both the first set of subcarriers and the second set of subcarriers.

[0146] Aspect 6: The method according to any one of aspects 1, 2, 3, 4, or 5, wherein applying the phase rotation comprises applying a phase rotation to each of the second set of subcarriers.

[0147] Aspect 7: The method according to any one of aspects 1 or 6, wherein the PPDU further comprises a Long Training Field (LTF) sequence and a Short Training Field (STF) sequence, wherein obtaining the first sub-PPDU comprises obtaining the first sub-PPDU comprising the LTF and STF sequences, and obtaining the second sub-PPDU comprises obtaining the second sub-PPDU comprising the LTF and STF sequences, and applying the phase rotation further comprises applying the phase rotation to the LTF and STF sequences.

[0148] Aspect 8: The method according to any one of aspects 1, 6, or 7, wherein applying the phase rotation comprises multiplying the second set of subcarriers by a constant phase rotation factor (-1).

[0149] Aspect 9: The method according to any one of aspects 1, 2, 3, 4, 5, 6, 7, or 8, wherein applying the phase offset includes applying the phase offset to each of the second set of subcarriers.

[0150] Aspect 10: The method according to any one of aspects 1 to 9, wherein the second set of subcarriers is sorted with sequential indices, and wherein applying the phase ramp includes applying an additional phase ramp π to each subcarrier in the order of the respective indices of each subcarrier.

[0151] Aspect 11: The method according to any one of aspects 1 to 10, wherein applying the phase ramp includes selecting the phase ramp as an equivalent cyclic delay in the time domain of the second set of subcarriers, and wherein the delay is part of the symbol duration of the data content.

[0152] Aspect 12: The method according to any one of aspects 1 to 10, wherein applying the phase ramp includes selecting the phase ramp by multiplying the index of the respective subcarrier k by (j2πkτ) / T power of the constant e, where T is the symbol duration of the data symbols of the data sequence, and τ is selected to be less than one percent of T.

[0153] Aspect 13: The method according to aspect 12, further comprising applying a phase offset.

[0154] Aspect 14: The method according to any one of aspects 1 to 13, wherein the first set of subcarriers includes a first subband of the wideband channel, wherein the second set of subcarriers includes a second subband of the wideband channel, and wherein transmitting the second set of subcarriers includes transmitting using a higher frequency subband of the wideband channel than when transmitting the first set of subcarriers.

[0155] Aspect 15: The method according to any one of aspects 1 to 14, wherein obtaining the first sub - PPDU includes obtaining the first sub - PPDU having dual - carrier modulation, and wherein obtaining the second sub - PPDU includes obtaining the second sub - PPDU having the same dual - carrier modulation as the first sub - PPDU.

[0156] Aspect 16: The method according to any one of aspects 1 to 14, wherein transmitting the first sub - PPDU includes transmitting using dual - carrier modulation in a first single - spatial stream, and transmitting the second sub - PPDU includes transmitting using the dual - carrier modulation in a second single - spatial stream.

[0157] Aspect 17: The method according to any one of aspects 1 to 16, wherein transmitting the first sub - PPDU includes transmitting on at least one of an uplink subband and a downlink subband of a low - power indoor frequency band.

[0158] Aspect 18: The method according to any one of Aspects 1 to 17, wherein transmitting the first sub-PPDU includes transmitting in an orthogonal frequency division multiple access (OFDMA) resource unit (RU), and the OFDMA RU is one of the following: having 484 subcarriers in a 40 MHz bandwidth and replicated to have two (2) RU484s in an 80 MHz bandwidth, having 996 subcarriers in an 80 MHz bandwidth and replicated to have two (2) RU996s in a 160 MHz bandwidth, or having 2x996 subcarriers in a 160 MHz bandwidth and replicated to have two (2) RUs (2x996) in a 320 MHz bandwidth.

[0159] Aspect 19: The method according to any one of Aspects 1 to 18, further comprising modulating the data content of the first sub-PPDU and the data content of the second sub-PPDU using binary phase shift keying before transmission, and wherein transmitting includes transmitting the first sub-PPDU and the second sub-PPDU using dual carriers in a single spatial stream.

[0160] Aspect 20: The method according to any one of Aspects 1 to 19, wherein the first set of subcarriers includes a first sub-band of the wideband channel, the second set of subcarriers includes a second sub-band of the wideband channel, and the first set of subcarriers is contiguous and does not overlap with the second set of subcarriers.

[0161] Aspect 21: The method according to any one of Aspects 1 to 20, further comprising: obtaining a third sub-PPDU including the data content of the PPDU; applying at least one of phase rotation, phase offset, or phase ramp to a third set of subcarriers before transmission; obtaining a fourth sub-PPDU including the data content of the PPDU; applying at least one of phase rotation, phase offset, or phase ramp to a fourth set of subcarriers before transmission; and transmitting the third sub-PPDU on the third set of subcarriers of the wideband channel and transmitting the fourth sub-PPDU on the fourth set of subcarriers of the wideband channel.

[0162] Aspect 22: The method according to any one of Aspects 1 to 21, wherein the wideband channel is divided into four (4) sub-bands, and wherein applying the phase rotation includes multiplying the first, second, third, and fourth sub-bands by constant phase rotation factors (+1, -1, +1, +1), respectively.

[0163] Aspect 23: The method according to any one of aspects 1 to 22, wherein applying a phase ramp includes applying a phase ramp to a first subset of the second set of subcarriers and applying a zero phase ramp to a second subset of the second set of subcarriers, the method further including applying a phase ramp to a subset of the first set of subcarriers.

[0164] Aspect 24: The method according to any one of aspects 1 to 23, further including: applying different phase rotation factors to long training field subsequences of respective sub-PPDUs.

[0165] Aspect 25: A method for wireless communication by a wireless communication device, including: obtaining a first sub-PPDU from a physical layer convergence protocol (PLCP) protocol data unit (PPDU) including a data field having data content; obtaining a second sub-PPDU by duplicating the PPDU including the data content of the PPDU, wherein data fields of the first sub-PPDU and the second sub-PPDU are valid data fields of the PPDU and carry the same data as the PPDU; applying at least one of a phase rotation, a phase offset, or a phase ramp to at least one of a first RU (2x996) or a second RU (2x996); and transmitting the first sub-PPDU on the first RU (2x996) of a broadband channel and transmitting the second sub-PPDU on the second RU (2x996) of the broadband channel simultaneously, wherein the first sub-PPDU and the second sub-PPDU include a duplicated packet format (DUPed) PPDU.

[0166] Aspect 26: A wireless communication device, including: at least one processor; and at least one memory communicatively coupled to the at least one processor and storing processor-readable code, the processor-readable code being configured to, when executed by the at least one processor: obtain a first sub-PPDU from a physical layer convergence protocol (PLCP) protocol data unit (PPDU) including a data field having data content; obtain a second sub-PPDU by duplicating the PPDU including the data content of the PPDU; apply at least one of a phase rotation, a phase offset, or a phase ramp to at least a portion of a second set of subcarriers; and transmit the first sub-PPDU on a first set of subcarriers of a broadband channel and transmit the second sub-PPDU on the second set of subcarriers of the broadband channel simultaneously.

[0167] Aspect 27: The device according to aspect 26, wherein the PPDU further includes a long training field (LTF) sequence, wherein obtaining the first sub-PPDU includes obtaining the first sub-PPDU including the LTF sequence, and obtaining the second sub-PPDU includes obtaining the second sub-PPDU including the LTF sequence.

[0168] Aspect 28: The apparatus according to any one of aspects 26 or 27, wherein applying the phase rotation includes applying the same phase rotation to the data content and the LTF sequence.

[0169] Aspect 29: The apparatus according to any one of aspects 26, 28, or 28, wherein the LTF includes an extremely high throughput (EHT) LTF.

[0170] Aspect 30: The apparatus according to any one of aspects 26, 27, 28, or 29, wherein the PPDU further includes a long training field (LTF) sequence, and wherein transmitting further includes transmitting the LTF sequence of the PPDU over the wideband channel using subcarriers from both the first set of subcarriers and the second set of subcarriers.

[0171] Aspect 31: The method according to any one of aspects 26, 27, 28, 29, or 30, wherein applying the phase rotation includes applying the phase rotation to each of the second set of subcarriers.

[0172] Aspect 32: The apparatus according to any one of aspects 26 to 31, wherein the PPDU further includes a long training field (LTF) sequence and a short training field (STF) sequence, wherein obtaining the first sub-PPDU includes obtaining the first sub-PPDU including the LTF and STF sequences, wherein obtaining the second sub-PPDU includes obtaining the second sub-PPDU including the LTF and STF sequences, and wherein applying the phase rotation further includes applying the phase rotation to the LTF and STF sequences.

[0173] Aspect 33: The apparatus according to any one of aspects 26 to 32, wherein applying the phase rotation includes multiplying the second set of subcarriers by a constant phase rotation factor (-1).

[0174] Aspect 34: The apparatus according to any one of aspects 26 to 33, wherein applying the phase offset includes applying the phase offset to each of the second set of subcarriers.

[0175] Aspect 35: The apparatus according to any one of aspects 26 to 34, wherein the second set of subcarriers are sorted in sequential index, and wherein applying the phase ramp includes applying an additional phase ramp π to each subcarrier in the order of each subcarrier's respective index.

[0176] Aspect 36: The apparatus according to any one of aspects 26 to 35, wherein applying the phase ramp includes selecting the phase ramp as an equivalent cyclic delay in the time domain of the second set of subcarriers, and wherein the delay is a part of the symbol duration of the data content.

[0177] Aspect 37: The apparatus according to any one of aspects 26 to 35, wherein applying the phase ramp comprises selecting the phase ramp by multiplying the index of the respective subcarrier k by (j2πkτ) / T power of a constant e, where T is the symbol duration of the data symbols of the data sequence, and τ is selected to be less than one percent of T.

[0178] Aspect 38: The apparatus according to any one of aspects 26 to 37, further configured to apply a phase offset.

[0179] Aspect 39: The apparatus according to any one of aspects 26 to 38, wherein the first set of subcarriers comprises a first subband of the wideband channel, wherein the second set of subcarriers comprises a second subband of the wideband channel, and wherein transmitting the second set of subcarriers comprises transmitting using a higher frequency subband of the wideband channel than when transmitting the first set of subcarriers.

[0180] Aspect 40: The apparatus according to any one of aspects 26 to 38, wherein obtaining the first sub-PPDU comprises obtaining the first sub-PPDU having dual-carrier modulation, and wherein obtaining the second sub-PPDU comprises obtaining the second sub-PPDU having the same dual-carrier modulation as the first sub-PPDU.

[0181] Aspect 41: The apparatus according to any one of aspects 26 to 40, wherein transmitting the first sub-PPDU comprises transmitting in a single spatial stream using dual-carrier modulation, and wherein transmitting the second sub-PPDU comprises transmitting in a second single spatial stream using the dual-carrier modulation.

[0182] Aspect 42: The apparatus according to any one of aspects 26 to 40, wherein transmitting the first sub-PPDU comprises transmitting on at least one of an uplink subband and a downlink subband of a low-power indoor frequency band.

[0183] Aspect 43: The apparatus according to any one of aspects 26 to 42, wherein transmitting the first sub-PPDU comprises transmitting in an orthogonal frequency division multiple access (OFDMA) resource unit (RU), the OFDMA RU being one of: having 484 subcarriers in a 40 MHz bandwidth and replicated to have two (2) RUs484 in an 80 MHz bandwidth, having 996 subcarriers in an 80 MHz bandwidth and replicated to have two (2) RUs996 in a 160 MHz bandwidth, or having 2x996 subcarriers in a 160 MHz bandwidth and replicated to have two (2) RUs(2x996) in a 320 MHz bandwidth.

[0184] Aspect 44: The apparatus as described in any one of aspects 26 to 43 is further configured to modulate the data content of the first sub-PPDU and the data content of the second sub-PPDU using binary phase shift keying before transmission, and wherein the transmission comprises transmitting the first sub-PPDU and the second sub-PPDU using dual carriers in a single spatial stream.

[0185] Aspect 45: The apparatus as described in any one of aspects 26 to 44, wherein the first set of subcarriers comprises a first sub-band of the wideband channel, wherein the second set of subcarriers comprises a second sub-band of the wideband channel, and wherein the first set of subcarriers is contiguous and does not overlap with the second set of subcarriers.

[0186] Aspect 46: The apparatus as described in any one of aspects 26 to 45, wherein applying a phase ramp comprises applying a phase ramp to a first subset of the second set of subcarriers and applying a zero phase ramp to a second subset of the second set of subcarriers, and the apparatus is further configured to apply a phase ramp to a subset of the first set of subcarriers.

[0187] Aspect 47: The apparatus as described in any one of aspects 26 to 46 is further configured to apply different phase rotation factors to the long training field subsequences of the respective sub-PPDUs.

[0188] Aspect 48: A non-transitory processor-readable medium storing executable instructions that, when executed by one or more processors, cause the one or more processors to perform the following operations: obtain a first sub-PPDU from a physical layer convergence protocol (PLCP) protocol data unit (PPDU) comprising a data field having data content; obtain a second sub-PPDU by duplicating the PPDU comprising the data content of the PPDU; apply at least one of a phase rotation, a phase offset, or a phase ramp to at least a portion of a second set of subcarriers; and transmit the first sub-PPDU on a first set of subcarriers of a wideband channel and transmit the second sub-PPDU on the second set of subcarriers of the wideband channel simultaneously.

[0189] Aspect 49: A non-transitory processor-readable medium storing executable instructions that, when executed by one or more processors, cause the one or more processors to perform the following operations: obtain a first sub-PPDU from a Physical Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) including a data field having data content; obtain a second sub-PPDU by duplicating the PPDU including the data content of the PPDU, wherein the data fields of the first sub-PPDU and the second sub-PPDU are valid data fields of the PPDU and carry the same data as the PPDU; apply at least one of phase rotation, phase offset, or phase ramp to at least one of a first RU (2x996) or a second RU (2x996); and transmit the first sub-PPDU on the first RU (2x996) of a wideband channel and transmit the second sub-PPDU on the second RU (2x996) of the wideband channel simultaneously, wherein the first sub-PPDU and the second sub-PPDU include a duplicated packet format (DUPed) PPDU.

[0190] As used herein, "or" is intended to be interpreted in an inclusive sense unless explicitly indicated otherwise. For example, "a or b" can include only a, only b, or a combination of a and b. As used herein, a phrase that recites "at least one of" or "one or more of" a list of items refers to any combination of those items, including a single member. For example, "at least one of a, b, or c" is intended to cover the following examples: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c.

[0191] The various illustrative components, logics, logic blocks, modules, circuits, operations, and algorithmic processes described in connection with the implementations disclosed herein can be implemented as electronic hardware, firmware, software, or any combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been described generally in terms of their functionality and illustrated in the various illustrative components, boxes, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system.

[0192] Various modifications to the implementations described in this disclosure may be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0193] In addition, various features described in the context of separate implementations in this specification can also be implemented combinatorially in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented separately or in any suitable sub-combination in multiple implementations. Thus, although the features may have been described above as acting in a particular combination and even initially claimed as such, one or more features from the claimed combination can in some cases be removed from the combination, and the claimed combination can be directed to a sub-combination or a variant of a sub-combination.

[0194] Similarly, although the operations are depicted in the drawings in a particular order, this should not be construed as requiring that such operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired result. Additionally, the drawings may schematically depict one or more example processes in the form of a flowchart or a flow diagram. However, other operations not depicted may be incorporated into the example processes schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. Moreover, the separation of the various system components in the implementations described above should not be construed as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A method for wireless communication by a wireless communication device, comprising: Transmitting a single-user (SU) physical layer protocol data unit (PPDU) via a wireless channel, the transmission of the SU PPDU comprising: Transmitting a data field via a first set of subcarriers of the wireless channel; Transmitting a copy of the data field simultaneously with the transmission of the data field via a second set of subcarriers of the wireless channel, the copy of the data field being transmitted with a phase rotation applied to at least one of the second set of subcarriers; and Transmitting a long training field (LTF) via a third set of subcarriers of the wireless channel, the third set of subcarriers including the first set of subcarriers and the second set of subcarriers, the LTF carrying an LTF sequence associated with demodulating the data field and the copied data field.

2. The method of claim 1, wherein transmitting the data field comprises modulating a first set of data bits onto the first set of subcarriers, and wherein transmitting the copy of the data field comprises copying the modulated first set of data bits onto the second set of subcarriers.

3. The method of claim 2, wherein at least a subset of the second set of subcarriers is phase rotated by a factor of +1 or -1 relative to a corresponding subset of the first set of subcarriers.

4. The method of claim 1, wherein the wireless channel is an 80 MHz channel, the first set of subcarriers corresponds to a first 484-tone resource unit (RU), and the second set of subcarriers corresponds to a second 484-tone RU.

5. The method of claim 1, wherein the wireless channel is a 160 MHz channel, the first set of subcarriers corresponds to a first 996-tone resource unit (RU), and the second set of subcarriers corresponds to a second 996-tone RU.

6. The method of claim 1, wherein the wireless channel is a 320 MHz channel, the first set of subcarriers corresponds to a first two 996-tone resource units (RU), and the second set of subcarriers corresponds to a second two 996-tone RUs.

7. The method of claim 1, wherein the wireless channel is divided into a first subband, a second subband, a third subband, and a fourth subband, and wherein the phase rotation is applied as part of an operation of multiplying the first subband, the second subband, the third subband, and the fourth subband by constant phase rotation factors of +1, -1, +1, and +1, respectively.

8. The method of claim 7, wherein at least one of the first subband, the second subband, the third subband, or the fourth subband includes the first set of subcarriers, and at least another of the first subband, the second subband, the third subband, or the fourth subband includes the second set of subcarriers.

9. The method of claim 1, wherein the phase rotation is applied as part of an operation of applying at least one of a phase offset or a phase ramp to at least a first subset of the second set of subcarriers, the first subset of the second set of subcarriers including the at least one subcarrier.

10. The method according to claim 9, wherein the phase rotation is applied as part of the following operations: applying the phase ramp to the first subset of the second set of subcarriers and applying a zero phase ramp to the second subset of the second set of subcarriers.

11. The method according to claim 9, wherein the second set of subcarriers is sorted in sequential index, and wherein applying the phase ramp includes applying an additional phase ramp π to the second subset of subcarriers of the second set of subcarriers.

12. The method according to claim 9, wherein the phase ramp is associated with an equivalent cyclic delay in the time domain, and wherein the delay is part of the symbol duration of the data field.

13. The method according to claim 9, wherein applying the phase ramp comprises: Multiply each subcarrier in the second set of subcarriers by e j2πkτ / T , where k is the index of the corresponding subcarrier, T is the symbol duration, and τ is less than T.

14. The method according to claim 1, further comprising: transmitting a second copy of the data field simultaneously with the transmission of the data field via a fourth set of subcarriers of the wireless channel, the second copy of the data field being transmitted in a case where a second phase rotation is applied to at least one subcarrier in the fourth set of subcarriers; and transmitting a third copy of the data field simultaneously with the transmission of the data field via a fifth set of subcarriers of the wireless channel, the third copy of the data field being transmitted in a case where a third phase rotation is applied to at least one subcarrier in the fifth set of subcarriers.

15. An apparatus for wireless communication, comprising: at least one memory; and at least one processor communicatively coupled to the at least one memory and operative to: transmit a single-user (SU) physical layer protocol data unit (PPDU) via a wireless channel, the transmission of the SU PPDU including: transmitting a data field via a first set of subcarriers of the wireless channel; transmitting a copy of the data field simultaneously with the transmission of the data field via a second set of subcarriers of the wireless channel, the copy of the data field being transmitted in a case where a phase rotation is applied to at least one subcarrier in the second set of subcarriers; and transmitting a long training field (LTF) via a third set of subcarriers of the wireless channel, the third set of subcarriers including the first set of subcarriers and the second set of subcarriers, the LTF carrying an LTF sequence associated with demodulating the data field and the replicated data field.

16. The apparatus according to claim 15, wherein transmitting the data field includes modulating a first set of data bits onto the first set of subcarriers, and wherein transmitting the copy of the data field includes copying the modulated first set of data bits onto the second set of subcarriers.

17. The apparatus according to claim 16, wherein at least a subset of the second set of subcarriers is phase rotated by a factor of +1 or -1 with respect to a corresponding subset of the first set of subcarriers.

18. The apparatus according to claim 15, wherein the wireless channel is an 80 MHz channel, the first set of subcarriers corresponds to a first 484-tone resource unit (RU), and the second set of subcarriers corresponds to a second 484-tone RU.

19. The device according to claim 15, wherein the wireless channel is a 160 MHz channel, the first set of subcarriers corresponds to a first 996-tone resource unit (RU), and the second set of subcarriers corresponds to a second 996-tone RU.

20. The device according to claim 15, wherein the wireless channel is a 320 MHz channel, the first set of subcarriers corresponds to a first two 996-tone resource units (RU), and the second set of subcarriers corresponds to a second two 996-tone RUs.

21. The device according to claim 15, wherein the wireless channel is divided into a first subband, a second subband, a third subband, and a fourth subband, and wherein the phase rotation is applied as part of an operation of multiplying the first subband, the second subband, the third subband, and the fourth subband by constant phase rotation factors +1, -1, +1, and +1, respectively.

22. The device according to claim 21, wherein at least one of the first subband, the second subband, the third subband, or the fourth subband includes the first set of subcarriers, and at least another of the first subband, the second subband, the third subband, or the fourth subband includes the second set of subcarriers.

23. The device according to claim 15, wherein the phase rotation is applied as part of an operation of applying at least one of a phase offset or a phase ramp to at least a first subset of the second set of subcarriers, the first subset of the second set of subcarriers including the at least one subcarrier.

24. The device according to claim 23, wherein the phase rotation is applied by applying a phase ramp to the first subset of the second set of subcarriers and applying a zero phase ramp to a second subset of the second set of subcarriers.

25. The device according to claim 23, wherein the second set of subcarriers is sorted in sequential index, and wherein applying the phase ramp includes applying an additional phase ramp π to a second subset of subcarriers of the second set of subcarriers.

26. The device according to claim 23, wherein the phase ramp is associated with an equivalent cyclic delay in the time domain, and wherein the delay is part of the symbol duration of the data field.

27. The apparatus of claim 23, wherein applying the phase ramp comprises: Multiply each subcarrier in the second set of subcarriers by e j2πkτ / T , where k is the index of the corresponding subcarrier, T is the symbol duration, and τ is less than T.

28. The device according to claim 15, wherein the at least one memory further stores processor-readable code that, when executed by the at least one processor, is configured to: transmit a second copy of the data field simultaneously with the transmission of the data field via a fourth set of subcarriers of the wireless channel, the second copy of the data field being transmitted with a second phase rotation applied to at least one subcarrier of the fourth set of subcarriers; and transmit a third copy of the data field simultaneously with the transmission of the data field via a fifth set of subcarriers of the wireless channel, the third copy of the data field being transmitted with a third phase rotation applied to at least one subcarrier of the fifth set of subcarriers.

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