Apparatus and method for reliable communication in wireless networks

Abstract

A wireless transmitting station (110; 120) using a resource unit (RU) or multiple resource unit (MRU) in orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication is disclosed. The wireless transmitting station (110; 120) is configured to allocate, based on the bit sequence, a first subset of a plurality of subcarriers of the RU or MRU as data subcarriers for carrying modulated data and a second subset of the plurality of subcarriers of the RU or MRU as interference mitigation (IM) pilot subcarriers for carrying a plurality of predefined IM pilot symbols. Furthermore, the wireless transmitting station (110; 120) is configured to permute the plurality of subcarriers of the RU or MRU, including the first subset comprising data subcarriers and the second subset comprising IM pilot subcarriers, to obtain a plurality of permuted subcarriers of the RU or MRU.

Description

[0001] This application is a divisional application. The original application has the application number 202480050222.6 and the original application date is March 6, 2024. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This disclosure relates to wireless communications. More specifically, this disclosure relates to apparatus (specifically, access points (APs) and non-AP sites) and methods for reliable OFDM and OFDMA communication in wireless communication networks (specifically Wi-Fi networks). Background Technology

[0003] In wireless communication networks, the reliability of data transmission is typically assessed based on upper limits such as data transmission error rate and / or latency. For example, one mode of Ultra-Reliable Low Latency Communication (URLLC), defined by the 3GPP 5G standard, defines an upper limit of 0.001% for packet error rate while maintaining a latency of up to 1 millisecond. Reliability is also an important aspect of Wi-Fi networks, defined by the IEEE 802.11 standard framework and its subsequent versions, such as IEEE 802.11bn (Ultra High Reliability (UHR), also known as Wi-Fi 8).

[0004] In wireless communication networks, especially Wi-Fi networks, uncontrolled and unintended interference is one of the main factors hindering high reliability. Interference signals can occur in any bandwidth used within a Wi-Fi network. For example, narrowband interference can be caused by a variety of sources, such as Wi-Fi interference, 3GPP transmissions in unlicensed bands, 2 MHz narrowband assisted UWB (as part of IEEE 802.15.4ab), particularly in the 6 GHz band, and 1 / 2 / 4 MHz Bluetooth signals in the 2.4 GHz band. Interference can occur at any time, such as before or during the transmission of physical protocol data units (PPDUs) on a Wi-Fi link, i.e., during the transmission of the data-carrying portion of a frame or packet. If a Wi-Fi transmitter identifies an ongoing interfering transmission in a frequency subband, it can, for example, avoid using the corresponding subchannel by using preamble punching. However, this approach cannot address unintended interference generated during PPDU transmission, thus threatening link reliability.

[0005] Within the IEEE 802.11 standard framework, packet transmission reliability is typically improved by reducing the modulation and / or coding rate as defined by the modulation and coding scheme (MCS). For very strong interference, a minimum MCS may be necessary; in IEEE 802.11be, this minimum MCS is half the binary phase-shift keying (BPSK) code rate combined with dual-carrier modulation (DCM). Under certain conditions (e.g., in the 6 GHz band), half the BPSK code rate combined with DCM can be used with the DUP scheme specified in IEEE 802.11be draft 4.0, which can mitigate broadband interference generated during PPDU transmission, even though it was originally designed to address the different problems associated with the mandatory reduction of transmit power spectral density (PSD) in certain frequency bands. However, this is rather limited under relatively strong interference conditions. Furthermore, the DUP scheme is only applicable to channel bandwidths of at least 80 MHz (meaning a minimum of 20 MHz chunks of the transmitted signal are copied to increase link reliability) and is only defined for transmission to a single receiver. For the DUP scheme, data with a BPSK code rate of 1 / 2 combined with DCM (where the use of DCM effectively reduces the code rate to 1 / 4) is copied in the frequency domain using twice the bandwidth (using additional partial sign changes to reduce PAPR), thus roughly equivalent to an extremely low MCS using BPSK with a code rate of 1 / 8.

[0006] Furthermore, in IEEE 802.11be, DCM is only used with BPSK at half the code rate. This effectively means that DCM is an additional, lower (more robust) modulation and cannot be used with high code rates and high MCS. Therefore, traditional reliability enhancement mechanisms are flawed because they force the modulation to be reduced to BPSK (the lowest possible modulation) at half the code rate, thus significantly increasing packet length. For applications requiring high reliability, i.e., those needing low error rates while maintaining a certain latency ceiling, this type of approach is unsuitable. Summary of the Invention

[0007] The purpose of this disclosure is to provide improved devices, particularly access points and non-AP sites, for reliable OFDM and OFDMA communication in wireless networks, especially Wi-Fi networks, as well as methods.

[0008] The foregoing and other objectives are achieved through the subject matter of the independent claims. Other implementations will be apparent from the dependent claims, the specification, and the drawings.

[0009] According to a first aspect, a wireless transmitting station is provided for transmitting bit sequences to a wireless receiving station via a wireless channel using a resource unit (RU) or multiple resource unit (MRU) in orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication. The wireless transmitting station and wireless receiving station described in the first aspect can be WLAN or Wi-Fi transmitting stations and WLAN or Wi-Fi receiving stations according to the IEEE 802.11 standard framework.

[0010] According to the first aspect, the wireless transmitting station is used to allocate a first subset of a plurality of subcarriers of the RU or MRU as data subcarriers for carrying modulated data, particularly quadrature amplitude modulation (QAM) symbols, based on the bit sequence, and to allocate a second subset of the plurality of subcarriers of the RU or MRU as IM pilot subcarriers for carrying a plurality of predefined interference mitigation (IM) pilot symbols. Furthermore, according to the first aspect, the wireless transmitting station is used to replace the plurality of subcarriers of the RU or MRU, the plurality of subcarriers including those containing… The first subset of data subcarriers and containing The second subset of the IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU. The wireless transmitting station according to the first aspect is further configured to map the multiple permuted subcarriers onto multiple frequency subcarriers of the RU or MRU to generate a modulated signal; and to transmit the modulated signal to the wireless receiving station via the wireless channel. By including multiple IM pilot subcarriers in the transmission, the wireless transmitting station according to the first aspect helps the wireless receiving station suppress interference to the data portion of data packets, thereby improving the reliability of the communication link and data transmission between the transmitter and receiver.

[0011] In another possible implementation, the modulated signal includes a data portion of a physical protocol data unit (PPDU), wherein the data portion of the PPDU includes an OFDM or OFDMA symbol sequence, wherein the number of data subcarriers in the last symbol of the OFDM or OFDMA symbol sequence is a parameter. The number of data subcarriers is an integer multiple of the number of symbols in the OFDM or OFDMA symbol sequence and is less than the number of other (i.e., previous) symbols in the sequence. .

[0012] In another possible implementation, the parameter used to calculate the number of data subcarriers of the last OFDM symbol The value is equal to The value, the The value corresponds to the number of data subcarriers less than the first subset defined in the IEEE 802.11 standard framework (especially the revised IEEE 802.11ax / be / bn). Maximum RU or .

[0013] In another possible implementation, the parameter used to calculate the number of data subcarriers of the last OFDM symbol The value is given by the following equation:

[0014] ,

[0015] in, This indicates rounding to the nearest integer, especially rounding up or down. Used to determine: when the last OFDM or OFDMA symbol is not fully used by data symbols, and The value corresponds to the number of data subcarriers of the last symbol of the OFDM or OFDMA symbol sequence of the RU or MRU as defined by the IEEE 802.11 standard framework, wherein, .

[0016] In another possible implementation, the parameter used to calculate the number of data subcarriers of the last OFDM symbol The value is given by the following equation:

[0017] ,

[0018] in, This indicates rounding to the nearest integer, especially rounding up or down.

[0019] In another possible implementation, the wireless transmitting station is further configured to send an indication to the wireless receiving station, indicating that the RU or MRU to be transmitted to the wireless receiving station includes a second subset of the plurality of subcarriers of the RU or MRU, namely the plurality of IM pilot subcarriers.

[0020] In another possible implementation, the indication to the wireless receiving station further indicates the number of subcarriers of the first subset of the plurality of subcarriers of the RU or MRU. .

[0021] In another possible implementation, the wireless transmitting station is used to transmit the modulated signal to the wireless receiving station in the form of a physical protocol data unit (PPDU) via the wireless channel, wherein the indication includes one or more bits of one or more PHY header fields of the PPDU, and the one or more PHY header fields include a universal SIG (U-SIG) field and / or an ultra-high reliability SIG (UHR-SIG) field.

[0022] In another possible implementation, the wireless transmitting station is used to send a plurality of beacon frames to the wireless receiving station, wherein one or more of the plurality of beacon frames include the indication.

[0023] In another possible implementation, the wireless transmitting station includes a segment resolver for dividing the RU or MRU into multiple segments, such that each of the multiple segments includes the multiple ( RU or MRU) segments. The second subset of subcarriers One or more subcarriers, namely IM pilot subcarriers.

[0024] In another possible implementation, the segment resolver is used to divide the RU or MRU into the plurality of segments such that for each of the plurality of segments, the ratio between the number of subcarriers in the first subset and the number of subcarriers in the second subset is approximately equal.

[0025] In another possible implementation, the first subset of the plurality of subcarriers of the RU or MRU includes subcarriers corresponding to the RU or MRU as defined by the IEEE 802.11 standard framework. Multiple subcarriers ,in, .

[0026] In another possible implementation, the wireless transmitting station is configured to first allocate a first subset of the plurality of subcarriers of the RU or MRU, and then allocate the remaining subcarriers of the RU or MRU that are not part of the first subset as a second subset of the plurality of subcarriers of the RU or MRU.

[0027] In another possible implementation, the wireless transmitting station is configured to first allocate a second subset of the plurality of subcarriers of the RU or MRU, and then allocate the remaining subcarriers of the RU or MRU that are not part of the second subset as the first subset of the plurality of subcarriers of the RU or MRU.

[0028] In another possible implementation, the wireless transmitting station is used to allocate the second subset among multiple subcarrier subgroups distributed over one or more frequency ranges defined by the plurality of subcarriers of the RU or MRU, wherein each subcarrier subgroup comprises multiple consecutive subcarriers.

[0029] In another possible implementation, the RU or MRU defined by the IEEE 802.11 standard framework includes 26, 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484, 996+484+242, 2 996, 2 996+484, 3 996, 3 996+484 or 4 996 subcarriers.

[0030] In another possible implementation, the RU or MRU also includes multiple carrier frequency offset (CFO) pilot subcarriers.

[0031] In another possible implementation, the wireless transmitting station is used to perform the permutation operation using an LDPC subcarrier mapper as specified in the IEEE 802.11 standard framework.

[0032] In another possible implementation, the wireless transmitting station generates IM pilot subcarrier symbols for one or more of the plurality of IM pilot subcarriers by combining or cascading one or more generator binary phase shift keying (BPSK) symbol sequences once or more, and multiplying each generator BPSK symbol sequence by a factor of 1 or -1. As used herein, the BPSK symbol sequence of a specific length is a sequence of complex values, each complex value taking one of two different possible non-zero values ​​of the symbols, obtained from a bit sequence of the same length by mapping each bit to a corresponding point in the BPSK constellation diagram.

[0033] In another possible implementation, the one or more generator BPSK symbol sequences include one or more of the following sequences: [–1 1 –1 –1 –1 –1]; [1 –1 –1 –1 1 –1]; [1 1 1 –1 –1 –1]; and [–11 –1 –1 –1 –1 1 –1 –1 1 –1 1 1 1 1 –1 –1 –1].

[0034] In another possible implementation, in order to combine or cascade the one or more generator BPSK symbol sequences, the wireless transmitting station is used to insert up to five additional BPSK symbols between the one or more generator BPSK symbol sequences.

[0035] In another possible implementation, the wireless transmitting station is configured to transmit empty signals on one or more of the plurality of IM pilot subcarriers. In other words, in one implementation, the wireless transmitting station is further configured to transmit empty signals on one or more subcarriers of the second subset of the plurality of data subcarriers of the RU or MRU.

[0036] In another possible implementation, the wireless transmitting station is further configured to send an indication to the wireless receiving station, indicating that the RU or MRU to be transmitted to the wireless receiving station includes a second subset of the plurality of data subcarriers of the RU or MRU. As described above, in one implementation, the second subset of the plurality of data subcarriers of the RU or MRU carries the predefined IM pilot symbol.

[0037] In another possible implementation, the indication of the wireless receiving station also indicates the location of the second subset of the plurality of data subcarriers of the RU or MRU within the RU or MRU.

[0038] In another implementation, the wireless transmitting station is used to transmit a band-limited modulated signal to the wireless receiving station in the form of a physical protocol data unit (PPDU) via the wireless channel.

[0039] In another possible implementation, the indication includes one or more bits of one or more PHY header fields of the PPDU or trigger frame, wherein the one or more PHY header fields include a universal SIG (U-SIG) field and / or an ultra-high reliability SIG (UHR-SIG) field.

[0040] According to a second aspect, a method is provided for transmitting a bit sequence to a wireless receiving station via a wireless channel using a resource unit (RU) or multiple resource unit (MRU) in orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication. The method according to the second aspect includes the following steps:

[0041] Based on the bit sequence, a first subset of the multiple subcarriers of the RU or MRU is allocated as data subcarriers for carrying modulated data;

[0042] A second subset of the multiple subcarriers allocated to the RU or MRU is used as IM pilot subcarriers for carrying multiple predefined interference mitigation (IM) pilot symbols;

[0043] The plurality of subcarriers that replace the RU or MRU, the plurality of subcarriers including those comprising The first subset of data subcarriers and containing The second subset of IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU;

[0044] The plurality of permuted subcarriers are mapped onto the plurality of frequency subcarriers of the RU or MRU to generate a modulation signal; and

[0045] The modulated signal is transmitted to the wireless receiving station through the wireless channel.

[0046] The method according to the second aspect can be performed by the wireless transmitting station according to the first aspect. Therefore, other features of the method according to the second aspect directly derive from the functionality of the wireless transmitting station described in the first aspect and its various implementations described above and below.

[0047] According to a third aspect, a computer program product is provided, the computer program product including program code, which, when executed by a computer or processor, causes the computer or processor to perform the method according to the second aspect.

[0048] One or more embodiments are set forth in detail in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the specification, drawings, and claims. Attached Figure Description

[0049] The embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. In the drawings:

[0050] Figure 1 A schematic diagram of a wireless communication network, particularly a Wi-Fi network including a wireless transmitting station communicating with multiple wireless receiving stations according to an embodiment, is shown.

[0051] Figure 2 A schematic diagram of a module for transmitting a bit sequence of a wireless transmitting station according to an embodiment is shown;

[0052] Figure 3a , Figure 3b and Figure 3c A schematic diagram of an exemplary transmission processing chain implemented by a wireless transmitting station is shown;

[0053] Figure 4a and Figure 4b A diagram illustrating the allocation of data subcarriers and interference suppression pilot subcarriers in a resource element used by a wireless transmitting station according to different embodiments is shown;

[0054] Figure 5 A table showing the sizes of multiple resource elements and the number of data subcarriers in a resource element used by a wireless transmitting station according to an embodiment is shown;

[0055] Figure 6 A flowchart illustrating the steps of a method for transmitting a bit sequence to a wireless receiving station according to an embodiment is shown;

[0056] Figure 7 The diagram shows plotted curves illustrating the data transmission performance between a wireless transmitting station and a wireless receiving station operating according to different embodiments.

[0057] In the following text, the same reference numerals refer to the same or at least functionally equivalent features. Detailed Implementation

[0058] In the following description, reference is made to the accompanying drawings, which form part of this disclosure, illustrating specific aspects of embodiments of the disclosure or specific aspects in which embodiments of the disclosure may be used. It should be understood that embodiments of the disclosure may be used in other aspects and may include structural or logical variations not depicted in the drawings. Therefore, the following detailed description should not be construed in a limiting sense, and the scope of this disclosure is defined by the appended claims.

[0059] For example, it should be understood that the disclosure relating to the described method can also apply to the corresponding device or system for performing the method, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more units (e.g., functional units) to perform the described one or more method steps (e.g., one unit performs one or more steps, or multiple units perform one or more of multiple steps respectively), even if the one or more units are not explicitly described or illustrated in the drawings. On the other hand, for example, if a specific apparatus is described based on one or more units (e.g., functional units), the corresponding method may include a step to perform the function of one or more units (e.g., one step performs the function of one or more units, or multiple steps perform the function of one or more of multiple units respectively), even if the one or more steps are not explicitly described or shown in the drawings. Furthermore, it should be understood that, unless otherwise expressly stated, features of the various exemplary embodiments and / or aspects described herein can be combined with each other.

[0060] Figure 1 A wireless communication network 100 is illustrated, specifically a wireless communication network (also referred to herein as Wi-Fi network 100) based on the IEEE 802.11 standard framework. Wi-Fi network 100 includes a wireless transmitting station 110 (also referred to herein as Wi-Fi station 110), which can be implemented as a multi-antenna AP 110, and multiple wireless receiving stations 120 (also referred herein as other Wi-Fi stations 120), implemented, for example, as non-AP stations 120. Figure 1 As shown, by way of example, a non-AP site 120 may include a smartphone, laptop, tablet, desktop computer, or other type of wireless device 120. In several embodiments below, the AP 110 will be described in more detail as a wireless transmitting site 110. However, it should be understood that the non-AP site 120 may also be implemented as a wireless transmitting site according to the following embodiments.

[0061] like Figure 1As further shown, AP 110 includes processing circuitry 111 and a communication interface 113, particularly a wireless communication interface 113 that enables communication according to the IEEE 802.11 standard framework via channel 130. The processing circuitry 111 can be implemented in hardware and / or software and may include digital circuitry, or both analog and digital circuitry. The digital circuitry may include components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. AP 110 may also include a memory 115 for storing executable program code, which, when executed by the processing circuitry 111, causes AP 110 to perform the functions and methods described herein.

[0062] Similarly, such as Figure 1 As shown, one or more non-AP stations 120 include processing circuitry 121 and a communication interface 123, particularly a wireless communication interface 123 that enables communication according to the IEEE 802.11 standard framework via channel 130. The processing circuitry 121 can be implemented in hardware and / or software and may include digital circuitry, or both analog and digital circuitry. The digital circuitry may include components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. One or more non-AP stations 120 may also include a memory 125 for storing executable program code that, when executed by the processing circuitry 121, causes the one or more non-AP stations 120 to perform the functions and methods described herein.

[0063] like Figure 2 As shown, in one embodiment, the processing circuitry 111 of AP 110 may implement encoder 201, such as LDPC encoder 201, for encoding a message (i.e., a bit sequence) into codewords with a predefined coding rate. In one embodiment, encoder 201 is used to generate codewords using one or more of a plurality of LDPC codes defined by the IEEE 802.11 standard framework (e.g., IEEE 802.11n, IEEE 802.11ac, or any future evolution of the IEEE 802.11 standard framework).

[0064] like Figure 2 As further shown, in one embodiment, AP 110 may also include a modulator 203 for modulating the codeword generated by encoder 201 into multiple modulation symbols, such as QAM symbols, based on, for example, a QAM scheme. In one embodiment, modulator 203 is used to modulate the codeword generated by encoder 201 into multiple modulation symbols, i.e., a symbol stream, based on BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, and / or 4096-QAM schemes. In one embodiment, modulator 203 is used to modulate the codeword generated by encoder 201 based on a modulation scheme defined by the IEEE 802.11 standard framework.

[0065] exist Figure 2 In the illustrated embodiment, the transmission processing chain of AP 110, implemented by the processing circuitry 111 and / or communication interface 113 of AP 110, may further include an OFDM / OFDMA module 205 and an analog RF module 207. For example, in the case of IEEE 802.11ac, symbol streams can be transmitted via OFDM and / or OFDMA technologies, which may involve additional steps implemented by the OFDM / OFDMA module 205, such as serial-to-parallel conversion before calculating the inverse fast Fourier transform (IFFT). The analog RF module 207 can be used to generate actual antenna feed signals for generating RF transmissions to multiple non-AP sites 120 based on the output from the OFDM / OFDMA module 205.

[0066] Before describing in more detail the different embodiments of the wireless transmitting station 110 (e.g., AP 110), some technical background and terminology will be introduced below using one or more of the following abbreviations:

[0067] AP access point

[0068] BCC binary convolutional code

[0069] BPSK binary phase shift keying

[0070] BW bandwidth

[0071] CFO carrier frequency offset

[0072] CSD Circular Shift Delay

[0073] DCM dual-carrier modulation

[0074] DUP copy transfer (defined in the IEEE 802.11be standard)

[0075] FEC Forward Error Correction

[0076] IDFT / IFFT Discrete / Inverse Fast Fourier Transform

[0077] IEEE Institute of Electrical and Electronics Engineers

[0078] IM interference suppression

[0079] LDPC (Low-Density Parity Check)

[0080] LTF long training field

[0081] MCS modulation and coding scheme (code rate)

[0082] MIMO (Multiple Input Multiple Output)

[0083] MRC maximum ratio merging

[0084] MRU Multi-Resource Unit

[0085] MU Multi-User

[0086] MVDR minimum variance distortion-free response

[0087] N_CBPS Number of bits per OFDM symbol encoding

[0088] N_DBPS Number of bits of data information per OFDM symbol

[0089] OFDM (Orthogonal Frequency Division Multiplexing / Multi-access)

[0090] PAPR Peak-to-average power ratio

[0091] PER package error rate

[0092] PHY physical layer

[0093] PPDU (Physical Layer Protocol Data Unit)

[0094] PSD power spectral density

[0095] QAM Quadrature Amplitude Modulation

[0096] RU resource unit

[0097] RX / Rx receiver

[0098] SIR signal interference power ratio

[0099] SNR signal-to-noise power ratio

[0100] STA sites can be AP STAs or non-AP STAs.

[0101] STF Short Training Field

[0102] TX / Tx transmitter

[0103] UHR Ultra-High Reliability

[0104] U-SIG General Signal Fields (Signal field names in 802.11be)

[0105] UWB Ultra-Broadband

[0106] WLAN wireless local area network

[0107] Prior to 802.11ax, the IEEE 802.11 WLAN standard (including 802.11a / g / n / ac) only supported OFDM mode, where the entire bandwidth (BW) was used to transmit data to a single STA or multiple STAs (in multi-user MIMO mode). Starting with 802.11ax (and then 802.11be), OFDMA was supported, where non-overlapping portions of the BW (called resource elements or RUs) can be allocated to one or more STAs. The standard defines the RUs supported for different channel bandwidths (e.g., 20 MHz and 40 MHz BWs). Specifically for the 20 MHz case, a transmitting station can choose to use 242-subcarrier RUs to transmit over the entire BW (to one or more STAs, which transmit in MU-MIMO mode), or use OFDMA, where any combination of non-overlapping RUs with fewer than 242 subcarriers can be used. Specifically, transmitting stations can choose to transmit on RUs of sizes 26, 52, or 106 subcarriers (IEEE 802.11be also supports MRUs, such as combinations of 52+26 and 106+26 subcarriers). In IEEE 802.11ax and 802.11be, a single RU (or an MRU in the case of IEEE 802.11be) can be assigned to each receiving STA in a PPDU, which can contain data destined for multiple receiving STAs. It should be noted that while a 52-subcarrier RU is exactly twice the size of a 26-subcarrier RU, a 106-subcarrier RU is slightly larger than two 52-subcarrier RUs (because a pair of empty subcarriers, reserved as spectrum protection between 52-subcarrier RUs, are now included as additional subcarriers in a 106-subcarrier RU), and a 242-subcarrier RU is larger than two 106-subcarrier RUs (due to 30 additional subcarriers).

[0108] Figure 3a , Figure 3b and Figure 3c A schematic diagram of an exemplary transmission processing chain conforming to the IEEE 802.11 standard framework is shown. As will be described in further detail below, the wireless transmitting station 110 according to an embodiment may include and / or implement Figure 3a , Figure 3b and Figure 3c One or more processing blocks of one of the transmission processing chains shown.

[0109] Figure 3a The transmission processing chain of LDPC encoded data defined by the IEEE 802.11 standard framework, particularly IEEE 802.11be and 802.11ax, is illustrated. Bits from the MAC layer undergo FEC pre-padding in block 301 (if applicable), scrambling in block 303, encoding using LDPC encoder 305, and FEC post-padding in block 306. If multiple spatial streams are used, the FEC post-padding bits are partitioned between the spatial streams by stream parser 307 before being fed to the corresponding constellation mapper 309, which applies a constellation mapping process (e.g., using BPSK / QPSK / 16-QAM, etc.) to the bitstreams. The resulting modulation symbols, particularly QAM symbols, are frequency-interleaved using LDPC subcarrier mapper 311. A cyclic shift delay (CSD) is then applied to each spatial stream via block 312, followed by spatial mapping (e.g., beamforming) and mapping to subcarriers (see block 313). An IDFT / IFFT operation is then applied via block 315, which creates samples of the OFDM symbols in the time domain. Finally, a guard interval can be inserted in block 317, and the analog and RF block 319 can generate the actual antenna feed signal based on the output from the preceding blocks for generating RF transmissions to multiple radio receiving sites 120 (e.g., non-AP sites 120). It should be understood that frequency mapping block 313 maps the allocation for each STA to a subcarrier / tone used in the frequency domain before IDFT / IFFT block 315, which processes the entire OFDM symbol (which may contain data allocated to multiple target sites). In other words, all blocks, i.e. modules, that are executed independently for each allocation before the frequency mapping operation is performed.

[0110] Figure 3b The transmission processing chain of BCC-encoded data defined by the IEEE 802.11 standard framework, particularly IEEE 802.11be and 802.11ax, is shown. Bits from the MAC layer undergo FEC pre-padding via block 301 (if applicable), scrambling via block 303, encoding using BCC encoder 305, and FEC post-padding via block 306.

[0111] If multiple spatial streams are used, the FEC-paded bits are partitioned between the spatial streams by the stream resolver 307. The bits are then interleaved via the corresponding BCC interleaver block 309 and mapped to points in the selected constellation (e.g., BPSK / QPSK / 16-QAM, etc.) via the corresponding constellation mapper 311. A cyclic shift delay can be applied for each spatial stream by the corresponding block 312, followed by spatial mapping (e.g., beamforming), then mapping to subcarriers (see block 313), and then an IDFT / IFFT operation is applied via block 315, which creates samples of OFDM symbols in the time domain. Finally, a guard interval can be inserted in block 317, and the analog and RF block 319 can generate the actual antenna feed signal based on the output from the preceding blocks for generating RF transmissions to multiple radio receiving sites 120 (e.g., non-AP sites 120). It should be understood that the frequency mapping block / module 313 maps the allocation of each STA to the subcarrier used on the frequency before the IDFT / IFFT block / module 315, which processes the entire OFDM symbol (which may contain multiple allocations). In other words, all blocks / modules prior to the frequency mapping operation are performed independently for each allocation.

[0112] Figure 3c The transmission processing chain for LDPC-encoded data, defined by the IEEE 802.11 standard framework (specifically IEEE 802.11be and 802.11ax), is shown for cases where the RU size is greater than 996 subcarriers. In this case, the data bits (after encoding and stream parsing, which is consistent with the above) are processed in a specific manner. Figure 3a (The same as the embodiment) is divided into multiple segments of no more than 996 subcarriers by multiple segment resolvers 308a, such as Figure 3c As shown. After dividing the bits between segments, they are mapped to QAM, and in accordance with the above. Figure 3a The implementation performs LDPC subcarrier mapping independently for each segment in the same manner, and then reassembles them by the corresponding segment inverse parser 308b. However, according to IEEE 802.11ax, segments always have the same size (e.g., 2 × 996 subcarriers), while multiple RUs according to IEEE 802.11be are not necessarily symmetrical, and the component RUs (and therefore segment sizes) are not necessarily the same (e.g., an MRU of size 996 + 484). The IEEE 802.11be standard defines how bits are divided between segments, especially for segments of different sizes.

[0113] The IEEE 802.11ax and 802.11be standards define BCC interleaving for each effective RU size (see [link]). Figure 3bBlock 309) and LDPC subcarrier mapping (see ... Figure 3a The operation of block 311). As used herein, the term “RU size” should also be understood to refer to “MRU size” where applicable, as in the case of possible subsequent versions of IEEE 802.11be and the IEEE 802.11 family of standards. The interleaving parameters defined for each RU size are designed to avoid excessively small separation in the frequency domain between the subcarriers of the RU, which carry information encoded by consecutive bits (or QAM) in the payload, to produce sufficient frequency diversity and improve detection performance at the wireless receiving site 120.

[0114] To track and compensate for any residual carrier frequency offset (CFO) and phase noise, CFO pilots (represented as predefined BPSK symbols modulating a specific predefined subcarrier, both known to the radio receiving station) are transmitted throughout the PPDU and inserted into almost every transmitted OFDM symbol in the frame, including OFDM symbols carrying LTF and data and OFDM symbols carrying the SIG field: L-SIG, U-SIG, UHR-SIG. The number of CFO pilots is defined by the IEEE 802.11 standard framework for different RUs as follows:

[0115]

[0116] CFO pilots do not perform LDPC subcarrier mapping or any form of frequency interleaving.

[0117] The following section describes a simple example illustrating how wireless receiving stations traditionally attempt to handle or mitigate interference. For simplicity, assume a single spatial flow for both the desired target signal and the interfering signal. The dimension of all vectors involved (in bold) is equal to the number of receiving antennas, which is assumed to be greater than 1. The signal received by the wireless receiving station can be represented in the following form:

[0118] ,

[0119] in, Indicates the received signal. Indicates the required target signal The channel, The relationship between noise intensity and SNR is as follows: ), This represents normalized additive white Gaussian noise (AWGN). Indicates passing through the channel The interference signal. The covariance of the noise and interference terms is given by the following matrix. Given:

[0120] ,

[0121] in, Represents the expected value, symbol This represents Hermitian conjugate. If the covariance is known to the wireless receiving station, the station can use it to compute a minimum variance distortionless response (MVDR) beamformer (which is equivalent to whitening spatial noise and interference before demodulation) to estimate the transmitted signal as follows:

[0122] .

[0123] It should be understood that wireless receiving sites can employ alternative interference suppression schemes to traditionally mitigate interference.

[0124] Both IEEE 802.11ax and 802.11be define partial data usage (if applicable) for the last OFDM symbol (within the PPDU). To allow the radio receiving station more time to decode packets and prepare its response, data does not need to be padded to fill the entire last OFDM symbol. Instead, the last OFDM symbol is typically divided into four (usually unequal) "parts," and padding is performed only on the last "part" containing the data.

[0125] For example, in a 242-subcarrier RU, the number of its subcarriers (i.e., subcarriers used for data) is (expressed as...) The value is 234, and the remaining 242 – 234 = 8 subcarriers are used for the CFO pilot. (Parameters) The size of such a "part" is defined, in which case the parameter is defined in the standard as follows: This means that if the number of QAMs generated by the data is less than or equal to 60, only the first "part" is padded with data, and the remaining 234 – 60 = 174 subcarriers are padded (after FEC), which is typically ignored by the receiving station. Similarly, if the number of QAMs generated by the data is greater than 60 but less than or equal to 120, only the first two "parts" are padded with data, and the remaining 234 – 120 = 114 subcarriers are padded (after FEC), which is ignored by the receiving station. Parameters The value is defined by the IEEE 802.11 standard framework for each RU size.

[0126] The embodiments disclosed herein support mitigation of interference by transmitting known pilots (referred to herein as interference mitigation (IM) pilots) within an RU (or MRU) distributed across the entire bandwidth of the RU or MRU allocated for data transmission, such that one or more wireless receiving stations 120 can use these IM pilots to estimate and mitigate interference. In the following several different embodiments, embodiments for distributing IM pilots over frequencies will be described, some of which minimize changes to existing designs.

[0127] Typically, wireless transmitting station 110 (or alternatively, station 120 when acting as a transmitter) is used to allocate a first subset of multiple subcarriers of RU or MRU based on a bit sequence as a means of carrying modulated data. A data subcarrier, and a second subset of multiple subcarriers of the RU or MRU are allocated as pilot symbols for carrying multiple predefined interference suppression (IM) symbols. Each IM pilot subcarrier. Furthermore, the wireless transmitting station 110 is used to replace multiple subcarriers of the RU or MRU, said multiple subcarriers including those containing... The first subset of data subcarriers and containing A second subset of IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU. The wireless transmitting station 110 is also used to map the multiple permuted subcarriers onto multiple frequency subcarriers (i.e., subcarriers of the RU or MRU) to generate a modulated signal and transmit the modulated signal to the wireless receiving station 120 (or alternatively, to the station 110 when the station 120 is operating as the wireless transmitting station 120) via the wireless channel 130.

[0128] In one embodiment, the wireless transmitting station 110 for generating the modulated signal in the manner described above may include and / or implement Figure 3a , Figure 3b or Figure 3c One or more of the multiple processing blocks shown. For example, in one embodiment, the wireless transmitting station 110 may include an LPDC subcarrier mapper 311 for permuting multiple subcarriers of a first subset and multiple IM pilot subcarriers of a second subset. In one embodiment, the wireless transmitting station 110 is used to transmit a band-limited modulated signal to the wireless receiving station 120 in the form of a physical protocol data unit (PPDU) via the wireless channel 130.

[0129] As will be described in more detail below, according to the embodiments disclosed herein, the number of data subcarriers (Therefore, the number of IM pilot subcarriers) The number of data subcarriers can be selected by the wireless transmitting station 110 as any number less than the total number of RUs or MRUs, or selected as one or more specific values, such as the smaller RU or MRU size defined by the IEEE 802.11 standard framework. (Therefore, the number of IM pilot subcarriers) The number of data subcarriers selected by the wireless transmitting station 110 can be any number of embodiments less than the total number of RU or MRU data subcarriers. This can be used by both the transmitter and receiver to determine all LDPC-related parameters, such as the number of LDPC codewords and the number of punctured bits, and the number of data bits per symbol. ) and the number of encoded bits for each symbol ( In other words, the transmitter and receiver will use... And the payload size to calculate all the necessary parameters, instead of using And the payload size to calculate all the necessary parameters (as is done in a current WLAN transmitter).

[0130] According to one embodiment, in a size of Subcarriers, i.e., subcarriers (corresponding to each OFDM symbol) Within a RU or MRU (within one data subcarrier), the wireless transmitting station 110 is used to allocate any number of... Each data subcarrier is a first subset of multiple subcarriers of the RU or MRU, wherein... The remaining subcarriers (or at least a portion thereof), i.e. The IM pilots are assigned as a second subset defining the RU or MRU. It should be understood that, in principle, prior to the subcarrier mapping operation implemented by the radio transmitting station 110, Each data subcarrier can be located anywhere within an OFDM symbol. According to one embodiment, The number of data subcarriers can be used as the total number of subcarriers for either the RU or MRU. Before or after The subcarriers are placed consecutively. Similarly, Each IM pilot can be located anywhere, but is preferably located consecutively at the beginning or end of the frequency map.

[0131] After the data subcarriers and IM pilot subcarriers are allocated, the radio transmitting station 110 is used to apply the LDPC subcarrier mapping to all One or more LDPC subcarrier mappers 311 (in Figure 3a and Figure 3cThe wireless transmitting station 110 (illustrated and implemented according to an embodiment) operates on both data and IM pilot subcarriers (together) such that they are both distributed within the RU or MRU subcarrier boundaries. In one embodiment, the number of CFO pilots and the frequency positions of these CFO pilots remain the same as defined in IEEE 802.11ax / be, i.e. Each subcarrier can be used as a CFO pilot by the wireless transmitting station 110.

[0132] In one embodiment, the modulated signal includes a data portion of a physical protocol data unit (PPDU), wherein the data portion of the PPDU includes an OFDM or OFDMA symbol sequence, and the number of data subcarriers in the last symbol of the OFDM or OFDMA symbol sequence is a parameter. (As described above) an integer multiple of, and less than, the number of data subcarriers of the other symbols in the OFDM or OFDMA symbol sequence. In one embodiment, The value can be determined by the wireless transmitting station 110 in one of the following ways.

[0133] According to the first embodiment, It can be defined by the IEEE 802.11ax / be / bn standard. The maximum value, which is less than or equal to That is, the number of data subcarriers in the first subset. For example, if we take an example... and Then it is selected by the wireless transmitting station 110. The value can correspond to (in one exemplary case) a 52+26-subcarrier RU that is less than the value 82. For some very small RU sizes, such as a 26-subcarrier RU, a fixed value (e.g., 2) can be set.

[0134] According to another embodiment, the parameter used to calculate the number of data subcarriers in the last OFDM symbol can be based on the following equation. Select a new value not specified in IEEE 802.11ax / be / bn:

[0135] ,

[0136] in, This indicates rounding to the nearest integer. The number of data subcarriers in the last symbol of the OFDM or OFDMA symbol sequence used to determine the number of data subcarriers in the RU or MRU as defined by the IEEE 802.11 standard framework when the last OFDM or OFDMA symbol is not fully used by data symbols. For example, if for a 242-subcarrier RU, the value used is... and ,but The value can be For example, the round-down operation is 38, and the round-up operation is 39. It should be understood that these values ​​38 and 39 are approximately... 1 / 4 of the value.

[0137] According to another embodiment, a parameter is used to calculate the number of data subcarriers in the last OFDM symbol. The value is given by the following equation:

[0138] ,

[0139] in, This indicates rounding to the nearest integer.

[0140] In one embodiment, the wireless transmitting station 110 is configured to transmit an indication to the wireless receiving station 120, indicating that the RU or MRU to be transmitted to the wireless receiving station 120 includes a second subset of a plurality of subcarriers of the RU or MRU. In one embodiment, the indication to the wireless receiving station 120 may further indicate, for example, the number of subcarriers in the first subset of a plurality of subcarriers of the RU or MRU. The value. In one embodiment, the indication may include one or more bits of one or more PHY header fields of the PPDU (e.g., 1 bit (a fixed value for each RU size) indicating whether it is used and multiple bits indicating a specific size), wherein the one or more PHY header fields include a universal SIG (U-SIG) field and / or an ultra-high reliability SIG (UHR-SIG) field. As described above, in one embodiment, the wireless transmitting station 110 may be implemented as an AP and is used to transmit multiple beacon frames to the wireless receiving station 120 in the form of a non-AP station 120, wherein one or more of the multiple beacon frames include an indication.

[0141] As described above, in one embodiment, the wireless transmitting station 110 may include Figure 3cOne or more segment resolvers 308a are shown, and are used (when the RU or MRU is greater than 996 subcarriers) to divide the RU or MRU into multiple segments such that each of the multiple segments includes one or more subcarriers of a second subset of the multiple subcarriers of the RU or MRU. In one embodiment, each segment resolver 308a is used to divide the RU or MRU into multiple segments such that for each of the multiple segments, the ratio between the number of subcarriers in the first subset and the second subset is approximately equal. It should be understood that this implementation is similar to the segment resolver implementation specified in IEEE 802.11be.

[0142] As described above, according to other embodiments disclosed herein, the number of data subcarriers (Therefore, the number of IM pilot subcarriers) The size of the RU or MRU can be selected by the wireless transmitting station 110 as one or more specific values, such as the size of a smaller RU or MRU as defined by the IEEE 802.11 standard framework. Therefore, in one embodiment, the RU or MRU defined by the IEEE 802.11 standard framework includes 26, 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484, 996+484+242, 2 996, 2 996+484, 3 996, 3 996+484 or 4 996 subcarriers. It should be understood that the RU or MRU defined by the IEEE 802.11 standard framework is different from the RU or MRU used to allocate the first subset. For example, for MRU106+26, the first subset of multiple data subcarriers of MRU106+26 used by the radio transmitting station 110 based on the bit sequence is used as data subcarriers for carrying modulated data, especially quadrature amplitude modulation (QAM) symbols, where the number of subcarriers in the first subset corresponds, for example, the number of subcarriers in RU106 (i.e., an RU with 106 subcarriers).

[0143] Figure 4a , Figure 4b A diagram illustrating the allocation of data subcarriers and IM pilot subcarriers in the RU or MRU 420 used by the wireless transmitting station 110 according to different embodiments is shown. Figure 4aIn the example schematically shown, the first allocation subset is 242-subcarrier RU 410a for data, and the adjacent second allocation subset is 242-subcarrier RU 410b for IM pilots. The wireless transmitting station 110 uses a 484-subcarrier LDPC subcarrier mapping sequence to extend both the data and IM pilot symbols on the intrinsic frequencies of the OFDM symbol subcarriers.

[0144] In one embodiment, the wireless transmitting station 110 is configured to first allocate a first subset of a plurality of data subcarriers of the RU or MRU, and then allocate the remaining data subcarriers of the RU or MRU that are not part of the first subset as a second subset of the plurality of data subcarriers of the RU or MRU. Alternatively, the wireless transmitting station 110 is configured to first allocate a second subset of a plurality of data subcarriers of the RU or MRU, and then allocate the remaining data subcarriers of the RU or MRU that are not part of the second subset as a first subset of the plurality of data subcarriers of the RU or MRU.

[0145] According to one embodiment, in a size of That is, having 1 subcarrier (which corresponds to each OFDM symbol) Data subcarriers, of which Within the RU, the wireless transmitting station 110 allocates a valid number of data subcarriers (i.e., the first subset) corresponding to the number of RUs / MRUs that already conform to the IEEE 802.11 standard, denoted as... ,in, The remaining subcarriers Assigned to IM pilots, i.e., the second subset. It should be understood that prior to subcarrier mapping, The data subcarriers, i.e., the first subset of subcarriers, can in principle be placed anywhere within an OFDM symbol. According to one embodiment, The data subcarriers, that is, the first subset of the subcarriers, can be arranged continuously as follows: The front or back of a subcarrier Each item. As mentioned above, wireless transmitting station 110 is used for all Each subcarrier is mapped using LDPC subcarrier mapping. In other words, the LDPC subcarrier mapper operates on both the data and IM pilot subcarriers (together) so that they are both distributed across frequencies.

[0146] According to one embodiment, the number of CFO pilots for the RU or MRU is constant relative to 802.11ax / be, which means that Subcarriers (of which, These are used for CFO pilots, and their position in frequency is constant relative to existing standard specifications.

[0147] Figure 4b The 242-subcarrier RU (i.e., ) generated by the wireless transmitting station 110 according to an embodiment is shown. Example 420, where, One data subcarrier (corresponding to a multi-RU of size 106+26) and Each IM pilot subcarrier undergoes LDPC subcarrier mapping corresponding to 242-subcarrier RU 420 (a subcarrier mapping sequence of length 234). In one embodiment, the ultra-high reliability (UHR) short training field (STF) and long training field (LTF) can occupy the same subcarriers as the union of the data and IM pilot subcarriers. Figure 4b Described in Figure 3a and Figure 3b The diagram shows the allocation of all 256 input bins of IDFT block 315, including the CFO pilot and (empty) guard subcarriers at the channel BW edges and center, as well as the data and IM pilot subcarriers. It should be understood that... Figure 4b In the RU 420, the data subcarrier (e.g., exemplary data subcarrier 421) has a value of 1, while the IM pilot subcarrier (e.g., exemplary IM pilot subcarrier 423) has a value slightly less than 1, and the CFO pilot subcarrier (e.g., exemplary CFO pilot subcarrier 425) has a value slightly greater than 1.

[0148] According to another embodiment, the IM pilot subcarrier can be assigned by the wireless transmitting station 110 at a predefined index, i.e., associated with a specific subcarrier, which will ultimately be mapped to a predefined subcarrier frequency after subcarrier mapping. More specifically, for a size of The RU (which corresponds to each OFDM symbol) Data subcarriers, of which and Both conform to the RU / MRU already supported in the IEEE 802.11 standard. According to the embodiment, the wireless transmitting station 110 can predefine the IM pilot subcarriers, i.e., the second subcarrier subset. There are indexes, among which... Below are two examples of predefined indexes:

[0149] ·for and , (Within the considered 242-subcarrier RU, there are also 8 subcarriers allocated to the CFO pilot). In this case, the 108 IM pilot indices can be distributed in consecutive frequency groups by the wireless transmitting station 110, and because The index can be defined, for example, by the MATLAB command sort([1:9:234, 2:9:234, 3:9:234, 4:9:234 231:234]) = [1,2,3,4,10,11,12,13,19,29,…,226,227,228,229,231,232,233,234], where the 108 IM pilot indices listed on the right side of the above equation form a subset of the 234 valid data subcarrier indices of the 242-subcarrier RU.

[0150] ·for and , In this case, the 108 IM pilot indices can be (almost) uniformly distributed in frequency by the wireless transmitting station 110, for example, by using the MATLAB command 1+floor(2^33 / 10^7). (0:107)) = [1,3,5,7,9,11,14,16,18,…,220,223,225,227,229,231,234] is defined, where the 108 IM pilot indices listed on the right side of the above equation form a subset of the 234 valid data subcarrier indices of the 242-subcarrier RU.

[0151] As described above, wireless transmitting station 110 can apply LDPC subcarrier mapping to all Each subcarrier (according to the IEEE 802.11 standard, RU's (Those subcarriers allocated for data transmission among the subcarriers) are mapped to corresponding frequency subcarrier indices. In one embodiment, the number of CFO pilots can be constant relative to the IEEE 802.11ax / be standard, which means that... Each subcarrier is used for the CFO pilot, and their position in the frequency remains constant. In one embodiment, the ultra-high reliability (UHR) short training field (STF) and long training field (LTF) can occupy the same subcarriers as the union of the data and IM pilot subcarriers.

[0152] As in Figure 4aAs already shown and described above, in one embodiment, the wireless transmitting station 110 can allocate data and IM pilots in separate active RUs 410a, 410b. More specifically, in one embodiment, the wireless transmitting station 110 can allocate data to a size of RU #1 of each subcarrier (which corresponds to each OFDM symbol) Data subcarriers, of which ), and assign the IM pilot to a size of RU #2 of each subcarrier (which corresponds to each OFDM symbol) Data subcarriers, of which Two RUs are contained in a size of In the larger RU (where, Size is The RU corresponds to Data subcarriers, of which In one embodiment, , and Each conforms to a different RU size specified in the IEEE 802.11 standard. and The number of data subcarriers.

[0153] The QAM corresponding to RU #1 and RU #2 is mapped to the larger RU in frequency (size is ). The corresponding subcarrier index within ) is then used. The LDPC subcarrier mapping is then applied by the wireless transmitting station 110 to all Each subcarrier (tone) means that all data and IM pilots are mixed and distributed across frequencies. In one embodiment, the number of CFO pilots remains constant, which means... Several subcarriers are used for the CFO pilot, and their positions in the frequency domain remain unchanged (corresponding to a size of...). (A larger RU). However, it should be understood that, unlike some of the previous embodiments, for this embodiment, there may be remaining (unused) subcarriers, and their number is .

[0154] According to another embodiment, the wireless transmitting station 110 is used to allocate multiple IM pilot subcarriers, i.e., a second subset of subcarriers, using a distributed RU. There have been proposals to distribute the subcarriers of the RU over a wider BW to increase the frequency spacing between two adjacent data subcarriers allocated to the same receiving station 120, rather than transmitting resource elements that are frequency-contiguous and localized. The primary motivation for this proposal is to support higher transmit power, which is sometimes limited by PSD restrictions imposed by regulatory agencies.

[0155] A simple example of a distributed RU is a 26-subcarrier RU distributed over a 20 MHz bandwidth. This might mean spacing every two adjacent subcarriers of the 26-subcarrier RU by 9 subcarriers (considering the subcarrier schemes of IEEE 802.11ax and IEEE 802.11be, there are 9 26-subcarrier RUs within 20 MHz). In this way, multiple distributed RUs can reside within a certain bandwidth, with each RU occupying an interleaved set of non-overlapping frequency subcarriers.

[0156] In an exemplary embodiment, the wireless transmitting station 110 may be used to allocate a single distributed RU for the IM pilot, while all other distributed RUs are used for data. For example, in 20 MHz, three 52-subcarrier RUs may be allocated for data and a single 52-subcarrier RU may be allocated for the IM pilot. After the frequency mapping operation (313), the frequency subcarriers of each 52-subcarrier RU are distributed within a 20 MHz bandwidth (with at least 4 subcarrier spacing).

[0157] According to the standard IEEE 802.11be, when the MRU size is greater than 996 subcarriers (corresponding to an 80 MHz frequency subblock), a segment resolver operation exists that defines how bits are distributed among the components within each 80 MHz frequency subblock. Furthermore, when the components in a frequency subblock are not all of the same size, the segment resolver defines how to handle the remaining bits. Additionally, when the RU size is greater than 996 subcarriers, LDPC subcarrier mapping operates separately for each 80 MHz frequency subblock (996 subcarriers or less). In one embodiment, the wireless transmitting station 110 handles cases involving RUs / MRUs larger than 996 by dividing the RU / MRU with a size greater than 996 into multiple RUs or MRUs (each RU or MRU with a size of 996 or less).

[0158] The following describes different embodiments of the IM pilot content (i.e., the payload or signal values ​​of the IM pilot subcarriers). In one embodiment, the IM pilot subcarriers may carry a sequence of IM pilot values, wherein the sequences are selected such that they result in a low PAPR of the IM pilot sequence (similar to the motivation used to set the CFO pilot sequence in IEEE 802.11n), and all sequences (corresponding to different BW values ​​and different RU sizes) can be generated from a single (or a few) short sequences, thereby reducing memory storage requirements. In one embodiment, the wireless transmitting station 110 may be used to generate BPSK symbol sequences M1, M2, M3, M4 using one or more of the following generators, where M1 = [–1 1 –1 –1 –1 –1], M2 = [1 –1 –1 –1 1 –1], M3 = [1 1 1 –1 –1 –1], and M4 = [M1 M2 M3] = [–1 1 –1 –1 –1 –1 1 –1 –1 –1 1–1 1 1 1 –1 –1 –1].

[0159] In one embodiment, the wireless transmitting station 110 can be used to generate a longer sequence from these generator sequences by concatenating and multiplying the generator sequences M1, M2, M3, and M4 by some total phase factor, particularly some symbol factor ±1. For example, in one embodiment, for a data MRU of size 106+26 or 52+26, or a data RU of size 52, where 24 IM pilots are used, the wireless transmitting station 110 can concatenate copies of generator sequences M1, M2, and M3 into [M1, M2, M3, M3] to form a BPSK symbol sequence of length 24 [–1 1 –1 –1 –1 –1 1 –1 –1 –1 1 –1 1 1 1 –1 –1 –1 1 1 –1 –1 –1], and then use it as the value assigned to the 24 IM pilot subcarriers. In other embodiments, when the wireless transmitting station 110 is used to operate with an RU or MRU of the following corresponding sizes, the following example of the concatenation and multiplication process of the generator BPSK symbol sequences M1, M2, M3, and M4 is used to generate the IM pilot sequence used by the wireless transmitting station 110:

[0160] In the case of a data RU of size 106 containing 30 IM pilots, the generator sequence can be concatenated as [M2, M3, M1, M2, M2] to form an IM pilot symbol sequence of length 30 [1 –1 –1 –1 1 –1 1 1 1 –1–1 –1 –1 1 –1 –1 –1 –1 1 –1 –1 –1 1 –1 –1 –1 1 –1 –1 –1 1 –1 –1 –1 1 –1];

[0161] In the case of a data RU of size 106 containing 54 IM pilots, the generator sequence can be concatenated as [M3, M2, M1, M2, M2, M2, M3, M2, M3] to form an IM pilot symbol sequence of length 54;

[0162] In the case of a data RU of size 242 containing 108 IM pilots, 6 copies of the generator sequence M4 can be concatenated, wherein each copy is multiplied by the corresponding overall symbol factor in the sequence [–1 1 –1 –1 –1 1] to form an IM pilot symbol sequence of length 108;

[0163] In the case of a data RU of size 484 containing 234 IM pilots or an MRU of size 484+242, 13 copies of the generator sequence M4 can be concatenated, wherein each copy is multiplied by the corresponding total symbol factor in the sequence [–1 1 1 1 1 –1 1 1 –1 1 1 1–1] to form an IM pilot symbol sequence of length 234;

[0164] With a data RU of size 996 containing 278 IM pilots, 15 copies of the generator sequence M4 can be cascaded, where each copy is multiplied by the corresponding overall symbol factor in the sequence [1 1 1 1 1 –1 1 –1 1 –1 –1 1 1 –1 –1]. The resulting symbol sequence of length 270 can be further appended with an 8-symbol sequence [1, M1, –1] to form an IM pilot symbol sequence of length 278.

[0165] With a data RU of size 996 containing 512 IM pilots, 28 copies of the generator sequence M4 can be cascaded, where each copy is multiplied by the corresponding overall symbol factor in the sequence [–1 1 1 –1 1 –1 1 1 1 1 –1 1 –1 1 1 –1 –1 –1 1 1 –1 1 1 –1 1 1 1]. The resulting symbol sequence of length 504 can be further appended with an 8-symbol sequence [1, M1, –1] to form an IM pilot symbol sequence of length 512.

[0166] In the case of a data RU or MRU with a size greater than 996, according to the IEEE 802.11 standard framework, a data RU or MRU is defined as an aggregation of constituent RUs or MRUs with a size less than or equal to 996; correspondingly, the IM pilot content of the data RU or MRU can be defined according to the content of the aggregated IM pilot of the corresponding constituent RU or MRU, for example, according to the process described above.

[0167] According to another embodiment, the wireless transmitting station 110 can be used to transmit zero values, i.e., empty signals, on at least some of the allocated IM pilot subcarriers. It should be understood that this supports a corresponding increase in the power of the allocated data subcarriers (e.g., if half of the subcarriers are allocated to the IM pilot, then if the IM pilot is transmitted with zero energy, the data power of the data subcarriers can be doubled, i.e., increased by 3 dB), while keeping the total power allocated to transmission on the RU under consideration constant.

[0168] In the following, several embodiments will be described regarding the signaling notification by a wireless transmitting station 110 to one or more wireless receiving stations 120 of the allocation it uses. Figure 5 The table shown lists various size values ​​for the RU or MRU, where, apart from the CFO pilot subcarriers, a portion of the subcarriers are used for data, and the remainder for IM pilots. Columns 5 through 8 of the table list the number of data subcarriers allocated for each RU or MRU in each 80 MHz frequency subblock (i.e., in the first subblock, and in other subblocks where applicable, i.e., when #subcarriers are greater than 996). Furthermore, columns 10 through 13 list the number of IM pilots allocated for each RU or MRU in each 80 MHz frequency subblock. The rightmost column shows the percentage of subcarriers allocated for data subcarriers across the entire RU / MRU size. For example, for a size of 2... The MRU has a size of 996+484, with corresponding data subcarrier counts of 702, 702, and 234 in these three subblocks, and IM pilot counts of 278, 278, and 234 respectively. It should be understood that in some cases, the same RU / MRU size can be used, but different choices can be made regarding the number of data subcarriers.

[0169] For example, based on Figure 5 The table shown indicates that the wireless transmitting station 110 can be used to implement the following signaling selection. According to the first embodiment, the wireless transmitting station 110 can use a single bit (i.e., a flag bit) to indicate that the transmission is ultra-reliable, i.e., including the allocation of the aforementioned data subcarriers and IM pilot subcarriers. In the case of non-OFDMA transmission, this single bit can be a portion of U-SIG / an overflow of UHR-SIG. In the case of OFDMA transmission, this single bit can be a portion of UHR-SIG. For Figure 5 Each RU size listed in the table supports only a single row (in the four cases where two rows with the same RU size are listed, one of the two rows is supported). For each allocated RU size indicated in the U-SIG / UHR-SIG / trigger frame, the number and location of the IM pilots are always known to both the transmitter and receiver.

[0170] According to another embodiment, the wireless transmitting station 110 may use at least two bits to indicate that the transmission is an ultra-reliable transmission, i.e., including the allocation of the data subcarriers and IM pilot subcarriers described above. These at least two bits (e.g., in a U-SIG / UHR-SIG / trigger frame) may indicate that the transmission includes the allocation of the data subcarriers and IM pilot subcarriers described above, and which portion of the RU is allocated for IM pilots. Here, more than one single value for the number of data subcarriers may be supported as an alternative operating mode for a specific RU size.

[0171] Figure 6 A flowchart illustrates the steps of a method 600 for operating a wireless transmitting station 110 to transmit a bit sequence to one or more wireless receiving stations 120 via a wireless channel 130 using an RU or MRU employing an OFDM or OFDMA communication scheme. Method 600 includes step 601: allocating a first subset of multiple subcarriers of the RU or MRU as data subcarriers for carrying modulated data, based on the bit sequence. Method 600 includes another step 603: allocating a second subset of the multiple subcarriers of the RU or MRU as IM pilot subcarriers for carrying multiple predefined interference mitigation (IM) pilot symbols. Furthermore, method 600 includes step 605: permuting the multiple subcarriers of the RU or MRU, said multiple subcarriers including... The first subset of data subcarriers and containing A second subset of IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU. Method 600 also includes step 607: mapping the multiple permuted subcarriers onto multiple frequency subcarriers of the RU or MRU to generate a modulated signal; and step 609: transmitting the modulated signal to the wireless receiving station 120 via wireless channel 130.

[0172] Figure 7 The graphs show the link performance (PER vs. SNR at the receiver) of wireless transmitting station 110 and wireless receiving station 120 using different TX-RX schemes according to different embodiments. Figure 7 The results shown are based on a link-level simulation with the following settings: 106-subcarrier RU, MCS 6 (64QAM code rate 3 / 4); interference to the entire RU, SIR=10 dB, SIR=5 dB; 1 Tx antenna, 4 Rx antennas, 1 spatial stream, and actual channel estimation. Figure 7The results shown illustrate: (a) the significant impact of MVDR-based interference suppression on receiver performance, depending on interference estimation based on the IM pilot inserted into the transmitted signal by the transmitter, according to the embodiment; (b) the error floor of the receiver using standard MRC, i.e., when the detection algorithm ignores the presence of interference; and (c) the performance of standard MRC when the transmitter chooses to use a lower MCS value (i.e., 2 or 3) to transmit data. Figure 7 As can be seen, even in the presence of strong interference, Rx interference suppression (made possible by the embodiment of the wireless transmitting station 110 disclosed herein) results in significant performance improvements and highly reliable transmission. Using a significantly lower MCS (e.g., MCS 3, i.e., 1 / 2 of the 16QAM code rate, implying a spectral efficiency of 2 bps / Hz, less than half the spectral efficiency of MCS 6, i.e., 3 / 4 of the 64QAM code rate, implying a spectral efficiency of 4.5 bps / Hz) still leads to undesirable error flatness.

[0173] Those skilled in the art will understand that “blocks” (“units”) in the various drawings (methods and apparatuses) represent or describe the functionality of embodiments of this disclosure (and are not necessarily independent “units” in hardware or software), thereby equally describing the functionality or features (unit = step) of apparatus embodiments and method embodiments.

[0174] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the described apparatus embodiments are merely exemplary. For example, the unit division is merely a logical functional division, and in actual implementation, it can be another division. For example, multiple units or components can be merged or integrated into another system, or some features can be ignored or not performed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be implemented through some interface. Indirect coupling or communication connection between devices or units can be implemented electronically, mechanically, or otherwise.

[0175] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiment solution according to actual needs.

[0176] Furthermore, the functional units in the embodiments of this disclosure can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into a unit.

Claims

1. A wireless transmitting station (1 10; 120), characterized by The wireless transmitting station includes a processing circuit (111), a communication interface (113), and a memory (115). The memory (115) stores executable program code, which, when executed by the processing circuit (111), causes the wireless transmitting station (110; 120) to: Based on the bit sequence, a first subset of multiple subcarriers of a resource unit (RU) or multiple resource unit (MRU) is allocated as a data subcarrier for carrying modulated data. A second subset of the multiple subcarriers allocated to the RU or MRU is used as IM pilot subcarriers for carrying multiple predefined interference mitigation (IM) pilot symbols; The plurality of subcarriers that replace the RU or MRU, the plurality of subcarriers including those comprising The first subset of data subcarriers and containing The second subset of IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU; The multiple permuted subcarriers are mapped onto multiple frequency subcarriers of the RU or MRU to generate a modulation signal; as well as The modulated signal is transmitted to the wireless receiving station (120; 110) via the wireless channel (130).

2. The wireless transmitting station (110; 120) according to claim 1, characterized in that, The modulated signal includes a data portion of a physical protocol data unit (PPDU), wherein the data portion of the PPDU includes an orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) symbol sequence, wherein the number of data subcarriers in the last symbol of the OFDM or OFDMA symbol sequence is a parameter. The number of data subcarriers is an integer multiple of the number of symbols in the OFDM or OFDMA symbol sequence and is less than the number of other symbols in the OFDM or OFDMA symbol sequence.

3. The wireless transmitting station (110; 120) according to claim 2, characterized in that, The parameter used to calculate the number of data subcarriers of the last OFDM symbol The value is given by the following equation: ， in, This indicates rounding to the nearest integer. Used to determine the number of data subcarriers of the last symbol in the OFDM or OFDMA symbol sequence of the RU or MRU as defined by the IEEE 802.11 standard framework when the last OFDM or OFDMA symbol is not fully used by data symbols.

4. The wireless transmitting station (110; 120) according to any one of claims 1 to 3, characterized in that, The wireless transmitting station (110; 120) is also configured to send an indication to the wireless receiving station (120; 110) indicating that the RU or MRU to be transmitted to the wireless receiving station (120; 110) includes a second subset of the plurality of subcarriers of the RU or MRU.

5. The wireless transmitting station (110; 120) according to claim 4, characterized in that, The wireless transmitting station (110; 120) is used to transmit the modulated signal to the wireless receiving station (120; 110) in the form of a physical protocol data unit (PPDU) via the wireless channel (130), wherein the indication includes one or more bits of one or more PHY header fields of the PPDU, and the one or more PHY header fields include a universal SIG (U-SIG) field and / or an ultra-high reliability SIG (UHR-SIG) field.

6. The wireless transmitting station (110; 120) according to any one of claims 1 to 4, characterized in that, The first subset of the plurality of subcarriers of the RU or MRU includes a plurality of subcarriers corresponding to the subcarriers of the RU or MRU.

7. The wireless transmitting station (110; 120) according to claim 6, characterized in that, The wireless transmitting station (110; 120) is used to first allocate a second subset of the plurality of subcarriers of the RU or MRU, and then allocate the remaining subcarriers of the RU or MRU that are not part of the second subset as the first subset of the plurality of subcarriers of the RU or MRU.

8. The wireless transmitting station (110; 120) according to claim 6, characterized in that, The wireless transmitting stations (110; 120) are used to perform the permutation operation using an LDPC subcarrier mapper.

9. The method (600) according to claim 6, characterized in that, The wireless transmitting stations (110; 120) are used to transmit empty signals on one or more of the plurality of IM pilot subcarriers.

10. A method (600) for transmitting a bit sequence to a wireless receiving station (120; 110) via a wireless channel (130) using a resource unit (RU) or multiple resource unit (MRU) in orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication, characterized in that, The method (600) includes: Based on the bit sequence, allocate (601) a first subset of the multiple subcarriers of the RU or MRU as data subcarriers for carrying modulated data; The second subset of the plurality of subcarriers of the RU or MRU is allocated (603) as IM pilot subcarriers for carrying a plurality of predefined interference mitigation (IM) pilot symbols; Replace (605) the plurality of subcarriers of the RU or MRU, the plurality of subcarriers including those comprising The first subset of data subcarriers and containing The second subset of IM pilot subcarriers is used to obtain multiple permuted subcarriers of the RU or MRU; The plurality of permuted subcarriers are mapped (607) onto the plurality of frequency subcarriers of the RU or MRU to generate a modulated signal; and The modulated signal (609) is transmitted to the wireless receiving station (120; 110) via the wireless channel (130).

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores program code that, when executed by a computer or processor, causes the computer or processor to perform the method (600) according to claim 10.

12. A computer program product, characterized in that, Includes a computer-readable storage medium for storing program code, which, when executed by a computer or processor, causes the computer or processor to perform the method (600) according to claim 10.

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