Apparatus and method for reliable communication in a wireless network

Abstract

A wireless local area network (WLAN) station (110; 120) is disclosed for communicating with another WLAN station (120; 110) in a WLAN (100). The WLAN station (110; 120) is used to send physical protocol data units (PPDUs) to the other WLAN station (120; 110) in interference mitigation (IM) mode, wherein the PPDUs are based on resource units (RUs). The WLAN station (110; 120) is used to permutate multiple data subcarriers of the RU to obtain multiple permuted data subcarriers of the RU. Furthermore, the WLAN station (110; 120) is used to map multiple IM pilot subcarriers onto multiple frequency subcarriers of the RU based on a predefined IM pilot subcarrier index set, wherein the predefined IM pilot subcarrier index set depends on the size of the RU.

Description

[0001] This application is a divisional application. The original application has the application number 202580003849.0 and the original application date is June 5, 2025. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This invention relates to wireless communication. More specifically, this invention relates to apparatus (specifically, access points (APs) and non-AP sites) for reliable communication in a wireless local area network (specifically, a Wi-Fi network according to the IEEE 802.11 standard framework). Background Technology

[0003] Uncontrolled and unpredictable interference is one of the main factors hindering the high reliability of wireless communication networks, specifically Wi-Fi networks. Interference signals can occur in any bandwidth used within a Wi-Fi network. For example, narrowband interference can originate from various sources, such as Wi-Fi interference, 3GPP transmissions in unlicensed frequency bands, 2 MHz narrowband-assisted ultra-wideband (UWB) (especially 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 transmission of physical protocol data units (PPDUs) on a Wi-Fi link, i.e., during the transmission of the data-bearing portion of a frame or data packet. If a Wi-Fi transmitter identifies an ongoing interference transmission in a frequency subband, it can, for example, avoid using the corresponding subchannel by using preamble punching. However, this type of approach cannot address unpredictable interference generated during PPDU transmissions, thus threatening the reliability of the link. Summary of the Invention

[0004] The object of this invention is to provide improved devices (specifically access points (APs) and non-AP sites) and methods for reliable communication in wireless local area networks (specifically Wi-Fi networks according to the IEEE 802.11 standard framework).

[0005] The above and other objectives are achieved through the subject matter claimed in the independent claims. Other implementations will be apparent from the dependent claims, the specification, and the drawings. In the following text, one or more of the following abbreviations / abbreviations may be used: AP (access point) CFO (Carrier Frequency Offset) CP (Cyclic Prefix) FEC Forward Error Correction IDFT / IFFT Inverse Discrete Fourier Transform / Inverse Fast Fourier Transform IEEE (Institute of Electrical and Electronics Engineers) IM interference mitigation LDPC (Low-Density Parity Check) MVDR (Minimum Variance Distortion-Free Response) OFDM / A Orthogonal Frequency Division Multiplexing / Orthogonal Frequency Division Multiple Access PER (Packet Error Rate) PPDU (Physical Layer Protocol Data Unit) QAM (Quadrature Amplitude Modulation) RF (Radio Frequency) RU (Resource Unit) A STA station (widely used in 802.11) can be an AP STA or a non-AP STA. TM Subcarrier Mapper / Mapper UWB (Ultra-Wideband) According to a first aspect, a transmitter wireless local area network (WLAN) station is provided for communicating with another receiver WLAN station within the WLAN. In an interference mitigation (IM) mode, the WLAN station according to the first aspect is used to transmit physical protocol data units (PPDUs) to the other WLAN station, wherein the signal carrying the PPDU is generated by a resource unit (RU) of the WLAN station based on an orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) scheme. The WLAN station according to the first aspect is used to: permutate (i.e., interleave) multiple data subcarriers of the RU to obtain multiple permuted data subcarriers of the RU; and map multiple IM pilot subcarriers onto multiple frequency subcarriers of the RU based on a predefined IM pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to IM pilot subcarriers), wherein the predefined IM pilot subcarrier index set depends on the size of the RU, i.e., the number of the multiple subcarriers. The WLAN site according to the first aspect is also used to map the plurality of replaced data subcarriers onto the plurality of remaining frequency subcarriers of the RU.

[0006] In another possible implementation, the WLAN site according to the first aspect includes a low-density parity check (LDPC) subcarrier mapper, wherein the LDPC subcarrier mapper (tonemapper, TM) is used to permutate the plurality of data subcarriers of the RU based on a predefined LDPC subcarrier mapping distance parameter D_TM, the predefined LDPC subcarrier mapping distance parameter D_TM depending on the size of the RU.

[0007] In another possible implementation, before mapping the plurality of permuted data subcarriers onto the plurality of remaining frequency subcarriers of the RU, the plurality of CFO pilot subcarriers are mapped onto the plurality of additional frequency subcarriers of the RU according to the WLAN site of the first aspect, based on a predefined carrier frequency offset (CFO) pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to CFO pilot subcarriers).

[0008] In another possible implementation, the RU is or includes a 242-tone RU, wherein the plurality of IM pilot subcarriers comprises 26 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–122 –112 –103 –94 –84 –75 –66 –57 –47 –38 –29 –19 –10 2 11 20 30 39 49 58 67 76 8595 104 113}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0009] In another possible implementation, the RU is or includes a 484-tone RU, wherein the plurality of IM pilot subcarriers comprises 52 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–244 –234 –225 –216 –206 –197 –188 –179 –169 –160 –151 –141 –132 –123 –114 –105 –95 –86 –76 –67 –58 –49 –40 –30 –21 –12 3 13 22 31 41 50 59 68 77 87 96 106 115 124 133 142 152 161 171 180 189 198 207 217 226 235}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0010] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–500 –490 –480 –470 –459 –449 –439 –429 –419 –409 –398 –388 –378 –368 –358 –348 –338 –327 –317 –307 –297 –287 –277 –267 –256 –246 –236 –226 –215 –205 –195 –185 –175 –165 –155 –144 –134 –124 –114 –104 –94 –83 –73 –63 –53 –43 –33 –23 –12 3 13 24 34 44 54 64 74 84 95 105 115 125 135 145 156 166 176 186 196 206 216 227 237 247 257 268 278 288 298 308 318 328 339 349 359 369 379 389 399 410 420 430 440 450 460 471 481 491}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0011] In another possible implementation, the RU is or includes a 242-tone RU, wherein the plurality of IM pilot subcarriers comprises 26 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–113 –104 –95 –85 –76 –67 –58 –49 –39 –30 –20 –11 –2 10 19 29 38 47 57 66 75 84 94 103 112 122}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0012] In another possible implementation, the RU is or includes a 484-tone RU, wherein the plurality of IM pilot subcarriers comprises 52 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: { –235 –226 –217 –207 –198 –189 –180 –171 –161 –152 –142 –133 –124 –115 –106 –96 –87 –77 –68 –59 –50 –41 –31 –22 –13 –3 12 21 30 40 49 58 67 76 86 95 105 114 123132 141 151 160 169 179 188 197 206 216 225 234 244}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0013] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: { –491 –481 –471 –460 –450 –440 –430 –420 –410 –399 –389 –379 –369 –359 –349 –339 –328 –318 –308 –298 –288 –278 –268 –257 –247 –237 –227 –216 –206 –196 –186 –176 –166 –156 –145 –135 –125 –115 –105 –95 –84 –74 –64 –54 –44 –34 –24 –13 –312 23 33 43 53 63 73 83 94 104 114 124 134 144 155 165 175 185 195 205 215 226 236 246 256 267 277 287 297 307 317 327 338 348 358 368 378 388 398 409 419 429 439 449 459 470 480 490 500}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0014] In another possible implementation, the RU is or includes a 242-tone RU, wherein the plurality of IM pilot subcarriers comprises 26 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–118 –108 –99 –89 –80 –71 –62 –53 –43 –34 –25 –15 –6 6 15 25 34 43 53 62 71 80 8999 108 118}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0015] In another possible implementation, the RU is or includes a 484-tone RU, wherein the plurality of IM pilot subcarriers comprises 52 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–240 –230 –221 –211 –202 –193 –184 –175 –165 –156 –147 –137 –128 –119 –110 –100 –91 –82 –72 –63 –54 –45 –35 –26 –17 –7 7 17 26 35 45 54 63 72 82 91 100 110 119 128 137 147 156 165 175 184 193 202 211 221 230 240}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 8.

[0016] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–496 –486 –476 –465 –455 –445 –435 –425 –415 –405 –394 –384 –374 –364 –354 –344 –333 –323 –313 –303 –293 –283 –273 –262 –252 –242 –232 –222 –211 –201 –191 –181 –171 –161 –150 –140 –130 –120 –110 –100 –90 –79 –69 –59 –49 –39 –29 –19 –8 7 17 28 38 48 58 68 78 89 99 109 119 129 139 149 160 170 180 190 200 210221 231 241 251 261 272 282 292 302 312 322 332 343 353 363 373 383 393 404414 424 434 444 454 464 475 485 495}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0017] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–495 –485 –475 –464 –454 –444 –434 –424 –414 –404 –393 –383 –373 –363 –353 –343 –332 –322 –312 –302 –292 –282 –272 –261 –251 –241 –231 –221 –210 –200 –190 –180 –170 –160 –149 –139 –129 –119 –109 –99 –89 –78 –68 –58 –48 –38 –28 –17 –78 19 29 39 49 59 69 79 90 100 110 120 130 140 150 161 171 181 191 201 211 222232 242 252 262 273 283 293 303 313 323 333 344 354 364 374 384 394 405 415 425 435 445 455 465 476 486 496}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0018] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–495 –485 –475 –464 –454 –444 –434 –424 –414 –404 –393 –383 –373 –363 –353 –343 –332 –322 –312 –302 –292 –282 –272 –261 –251 –241 –231 –221 –210 –200 –190 –180 –170 –160 –149 –139 –129 –119 –109 –99 –89 –78 –68 –58 –48 –38 –28 –17 –77 17 28} 38 48 58 68 78 89 99 109 119 129 139 149 160 170 180 190 200 210 221231 241 251 261 272 282 292 302 312 322 332 343 353 363 373 383 393 404 414 424 434 444 454 464 475 485 495}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0019] In another possible implementation, the RU is or includes a 996-tone RU, wherein the plurality of IM pilot subcarriers comprises 98 IM pilot subcarriers, and the predefined IM pilot subcarrier index set includes: {–496 –486 –476 –465 –455 –445 –435 –425 –415 –405 –394 –384 –374 –364 –354 –344 –333 –323 –313 –303 –293 –283 –273 –262 –252 –242 –232 –222 –211 –201 –191 –181 –171 –161 –150 –140 –130 –120 –110 –100 –90 –79 –69 –59 –49 –39 –29 –19 –8 8 19 29 39 49 59 69 79 90 100 110 120 130 140 150 161 171 181 191 201 211222 232 242 252 262 273 283 293 303 313 323 333 344 354 364 374 384 394 405 415 425 435 445 455 465 476 486 496}. For this implementation, the predefined LDPC subcarrier mapping distance parameter D_TM can have a value of 9.

[0020] According to a second aspect, a method is provided for operating a wireless local area network (WLAN) station to communicate with another WLAN station within the WLAN, wherein, in an interference mitigation (IM) mode, the WLAN station transmits a physical protocol data unit (PPDU) to the other WLAN station, wherein the PPDU is based on a resource unit (RU) of an orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) scheme (i.e., the signal carrying the PPDU is generated by the WLAN station based on the RU). The method according to the second aspect includes: Multiple data subcarriers of the RU are permuted (i.e. interleaved) to obtain multiple permuted data subcarriers of the RU; Based on a predefined IM pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to IM pilot subcarriers), multiple IM pilot subcarriers are mapped to multiple frequency subcarriers of the RU, wherein the predefined IM pilot subcarrier index set depends on the size of the RU (i.e., the number of multiple subcarriers). The multiple permuted data subcarriers are mapped onto the multiple remaining frequency subcarriers of the RU.

[0021] The method according to the second aspect can be performed by the WLAN station according to the first aspect. Furthermore, other features of the method according to the second aspect directly derive from the functionality of the WLAN station according to the first aspect and its various implementations described above and below.

[0022] According to a third aspect, a computer program product including program code is provided, which, when executed by a computer or processor, causes the computer or processor to perform the method according to the second aspect.

[0023] The following drawings and description illustrate one or more embodiments in detail. Other features, objects, and advantages will be apparent from the description, drawings, and claims. Attached Figure Description

[0024] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings: Figure 1 A schematic diagram illustrating a wireless local area network (WLAN) is shown, which includes a WLAN station according to an embodiment. The WLAN station is in the form of an access point (AP) and communicates with a plurality of other WLAN stations in the form of non-AP stations. Figure 2 The components of the transmission processing chain of a WLAN site are shown, which implements the LDPC™ method to extend the data subcarriers and IM pilot subcarriers in frequency. Figure 3 It shows the use of Figure 2 The LDPC™ method shown presents an exemplary frequency distribution of data subcarriers and IM pilot subcarriers. Figure 4 Components of a transmission processing chain for a WLAN site according to an embodiment are shown, the WLAN site implementing a fixed index to extend IM pilot subcarriers in frequency; Figure 5The components of a transmission processing chain for a WLAN site according to an embodiment are shown in more detail. This WLAN site implements a fixed index to extend IM pilot subcarriers in frequency. Figure 6 A flowchart illustrating a method for operating a WLAN site according to an embodiment is shown.

[0025] In the following text, the same reference numerals refer to the same or at least functionally equivalent features. Detailed Implementation

[0026] In the following description, reference is made to the accompanying drawings, which form part of this invention, illustrating specific aspects of embodiments of the invention or aspects that may be used with respect to embodiments of the invention. It should be understood that embodiments of the invention can be used in other aspects and include structural or logical variations not described in the drawings. Therefore, the following detailed description should not be construed in a limiting sense, and the scope of the invention is defined by the appended claims.

[0027] For example, it should be understood that the disclosure relating to the described method also applies to the corresponding apparatus or system used to perform the method, and vice versa. For instance, if one or more specific method steps are described, the corresponding apparatus 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 such one or more units are not explicitly described or illustrated in the accompanying drawings. Furthermore, if a specific apparatus is described based on one or more units such as 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 such one or more units are not explicitly described or illustrated in the accompanying drawings. Moreover, it should be understood that, unless otherwise explicitly stated, features of the various exemplary embodiments and / or aspects described herein can be combined with each other.

[0028] Figure 1 A wireless local area network (WLAN) 100 (also referred to as Wi-Fi network 100) based on the IEEE 802.11 standard framework is illustrated. The Wi-Fi network 100 includes a transmitter WLAN site 110 (also referred to herein as Wi-Fi site 110), which can be implemented in the form of a multi-antenna AP 110, and multiple receiver WLAN sites 120 (also referred to herein as other WLAN or Wi-Fi sites 120), such as non-AP sites 120. Figure 1As shown, as an example, a non-AP site 120 may include a smartphone, laptop, tablet, desktop computer, or other type of wireless device 120. Several embodiments of AP 110 as a transmitter WLAN site 110 will be described in more detail below. However, as will be understood, a non-AP site 120 may also be implemented as a transmitter WLAN site according to the following embodiments.

[0029] like Figure 1 As further illustrated, AP 110 includes processing circuitry 111 and a communication interface 113, specifically a wireless communication interface 113 capable of communication over channel 130 according to the IEEE 802.11 standard framework. 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, enables AP 110 to perform the functions and methods described herein.

[0030] Similarly, as Figure 1 As shown, one or more non-AP stations 120 include processing circuitry 121 and a communication interface 123, specifically a wireless communication interface 123 capable of communicating over channel 130 according to the IEEE 802.11 standard framework. 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, which, when executed by the processing circuitry 121, enables the one or more non-AP stations 120 to perform the functions and methods described herein.

[0031] As will be described in more detail below, AP 110 (or similarly, each of the non-AP sites 120) incorporates dedicated interference mitigation (IM) pilots (known to both the transmitter and receiver) into the transmitted PPDU. These IM pilots are used to estimate the covariance of interference at the receiver (e.g., non-AP site 120), including its time and frequency variations, and then to mitigate the interference. More specifically, AP 110 is used in an IM operating mode, in which AP 110 transmits PPDUs to one or more non-AP sites 120 using multiple frequency subcarriers. The payload of a frame includes a data payload associated with multiple data frequency subcarriers and multiple IM pilots interleaved with (i.e., interleaved between data payloads and associated with multiple IM pilot subcarriers). Such an IM operating mode is disclosed in more detail in WO 2025 / 051397, the entire contents of which are incorporated herein by reference.

[0032] Before describing more detailed embodiments of AP 110 and one or more non-AP sites 120 below, some technical background, specifically from the IEEE 802.11 WLAN standard framework, will be outlined. This technical background can be used to better understand and / or implement certain aspects of the embodiments disclosed herein.

[0033] One of the methods disclosed in WO 2025 / 051397 for frequency-spreading IM pilots and data QAM is the use of an LDPC subcarrier mapper 202. Hereinafter, this method will be referred to as the "LDPC-TM pre-IM insertion method," or simply the "LDPC-TM method," meaning that IM pilot insertion is performed at the input of the LDPC-TM box 202 before the subcarrier mapping operation is applied. Figure 2 As shown, for the 242-tone RU example, the IM pilots provided by box 204 (26 IM pilots in this example) are inserted together with the data QAM provided by box 201 (208 QAMs, i.e., data subcarriers, in this example) into LDPC TM 202. Since LDPC TM 202 is used to interleave its inputs in frequency (based on the LDPC subcarrier mapping distance parameter D_TM, i.e., the resulting output distance between two consecutive input subcarriers), in... Figure 2 In the example shown, it equals 9), therefore, if the IM pilot is inserted as a continuous block into the LDPC TM 202 (as suggested in WO 2025 / 051397), the IM pilot is spread almost uniformly across the entire frequency subband occupied by the RU, as... Figure 3 As shown. As will be understood, in Figure 2In the example shown, the ability to extend the IM pilot over the signal bandwidth is achieved through LDPC™ 202 and inputs 201 and 204. Therefore, instead of simply inputting a QAM block group into LDPC™ 202 (which interleaves the QAM block group in frequency), boxes 201 and 204 of AP 110 insert, for example, 208 QAM and 26 IM pilots into LDPC™ 202. The IM pilots can be inserted consecutively at the beginning or end of the QAM block group (or at more complex positions). As will be understood, if the IM pilot block group at the input of LDPC™ 202 is shifted up or down by a certain length relative to a larger data subcarrier block group, that length is twice the output size of box 204 (e.g., ...). Figure 2 As shown in example 26), the position of the IM pilot at the output of the LDPC TM 202 is shifted up or down by a single subcarrier depending on the shift direction at the input. Further details are described in WO 2025 / 051397, the entire contents of which are incorporated herein by reference.

[0034] Because some frequency subcarriers should be reserved for the CFO pilot provided by box 205, or are defined as unused by the IEEE 802.11 standard framework, these frequency subcarriers are skipped by frequency mapping box 203. Therefore, for Figure 2 The example assuming the exemplary 242-tone RU in the example, the result of LDPC™ 202 is non-uniform IM pilot distribution. For example... Figure 3 As shown, after LDPC TM 202, the gap (i.e., distance) between IM pilots alternates between 9 and 10 frequency subcarriers.

[0035] At the receiver, if the FFT output buffer is read based on the LDPC subcarrier demapper address, the IM pilots (assuming they are first inserted into the LDPC TM 202 before the data QAM, as suggested in the embodiments disclosed in WO 2025 / 051397) are read first and can be processed before data processing. This allows the receiver to apply interference mitigation (e.g., receive beamforming, such as MVDR beamformers) on data subcarriers belonging to the same OFDM symbol. However, receiver architectures that do not read the FFT output buffer based on the LDPC subcarrier demapper address may benefit from separating the IM pilots from the data subcarriers and processing the IM pilots before (and outside) the data path, similar to the processing of CFO pilots as defined in the IEEE 802.11 standard framework. From this perspective, it may be advantageous for the receiver to know the index of the IM pilots in advance and implement the receiver accordingly.

[0036] The embodiments disclosed herein utilize a surprising discovery that, for a specific choice of the number of IM pilots, the aforementioned LDPC™ method (in Figure 2 In the context of the above, both the LDPC TM method (where D_TM = K, D_TM = N_SD / N_SD_IM) and the predefined indexing method (described in more detail below) produce the same end result in frequency subcarrier allocation, provided that a smaller LDPC subcarrier mapping distance parameter D_TM value is used. Specifically, assuming there are N_SD data subcarriers, where N_SD_IM is the IM pilot (where N_SD is an integer multiple of N_SD_IM), the LDPC TM method (where D_TM = K, D_TM = N_SD / N_SD_IM) and the predefined indexing method (where D_TM = K–1, with the same N_SD_IM value) produce the same frequency subcarrier allocation. For example, for the 242-tone RU example described above, there are 234 data subcarriers, where D_TM = 9. For the LDPC TM method, 26 IM pilots can be used, where 26 x 9 = 234, and a total of 26 (IM pilots) + 208 (data QAM) are inserted into an LDPC TM input buffer of size 234. At the output of the subcarrier mapper in the LDPC TM method, the same result of the above process can be achieved by simply inserting 208 (data QAM) into an LDPC subcarrier mapping buffer of size 208, where 26 x 8 = 208, then applying the subcarrier mapping, where D_TM = 8, and subsequently inserting 26 (IM pilot) separately into a predefined position, as implemented in the embodiments of AP 110 and one or more non-AP sites disclosed herein. Therefore, both methods produce the same data and IM pilot index assignments, which will be described in more detail below.

[0037] However, as will be understood, there is neither a need to limit the predefined set of subcarrier indices for the inserted IM pilots to the set disclosed by example below, nor a need to limit the selection of predefined subcarrier indices based on the findings / observations described above, which are the reason for defining these specific disclosed sets.

[0038] As mentioned above, Figure 2The number of QAM and IM pilots inserted into the LDPC TM 202 using the LDPC TM method for an exemplary 242-tone RU is shown. Since the 242-tone RU consists of 8 CFO pilots, with the remaining 234 subcarriers used for data and IM pilots, the LDPC TM 202 operates on 234 inputs. If 26 IM pilots are allocated for data and the remaining 234–26=208 subcarriers are used, using the value of D_TM (now used for 242-tone RUs in future communication networks), the IM pilots will be almost uniformly distributed across every 9 subcarriers, since 234 / 26=9. If the 26 IM pilots are inserted into the LDPC TM 202 as a contiguous block group before the data QAM, the indices of the 26 IM pilots (before the CFO pilot insertion and considering the guard subcarriers surrounding the DC subcarriers) will be 1, 10, 19, 28, etc. (where 1 corresponds to the first index, before considering the guard subcarriers, etc.).

[0039] Figure 4An embodiment of an IM pilot insertion method is illustrated, which uses a fixed (i.e., predefined) index implemented by AP 110 (or one or more non-AP sites 120) to transmit a PPDU comprising multiple IM pilots. The PPDU is based on a resource unit (RU) of an orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) scheme. AP 110 (or one or more non-AP sites 120) is used to permutate (i.e., interleave) multiple data subcarriers of the RU to obtain multiple permuted data subcarriers of the RU. In one embodiment, LDPC TM 402 can permutate (i.e., interleave) multiple data subcarriers of the RU to obtain multiple permuted data subcarriers of the RU. Before permutation, AP 110 (or one or more non-AP sites 120) can allocate a subset of the multiple subcarriers of the RU as data subcarriers for carrying modulated data in QAM symbol form. AP 110 (or one or more non-AP sites 120) also, for example, uses frequency mapper 403 to map multiple IM pilot subcarriers (provided by box 404) onto multiple frequency subcarriers of the RU based on a predefined IM pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to IM pilot subcarriers). As will be described in more detail below, the predefined IM pilot subcarrier index set depends on the size of the RU, i.e., the number of multiple subcarriers. AP 110 (or one or more non-AP sites 120) is also used, for example, to map multiple permuted data subcarriers (i.e., the output of LDPC™ 402) onto multiple remaining frequency subcarriers of the RU via frequency mapper 403.

[0040] As described above, in one embodiment, the LDPC TM 402 of AP 110 (or one or more non-AP sites 120) is used to permutate multiple data subcarriers of the RU based on a predefined LDPC subcarrier mapping distance parameter D_TM, which depends on the size of the RU. Before mapping the multiple permuted data subcarriers onto multiple remaining frequency subcarriers of the RU, AP 110 (or one or more non-AP sites 120) can map the multiple CFO pilot subcarriers (by...) to multiple remaining frequency subcarriers of the RU based on a predefined CFO pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to CFO pilot subcarriers). Figure 4 (The box 405 provides) is mapped to multiple additional frequency subcarriers of the RU.

[0041] exist Figure 4In the illustrated embodiment, the number of subcarriers is indicated for the exemplary 242-tone RU. For this example, the 26 IM pilots provided by block 404 are inserted into the frequency mapper 403 after LDPC TM 402. Therefore, for this 242-tone RU example, LDPC TM operates on 208 inputs (due to the allocation of 26 IM pilots for data and the remaining 234 – 26 = 208 subcarriers). To achieve the same result as described above... Figure 2 and Figure 3 The same result is obtained as described in the context of the LDPC TM method, using a value of 8 for the LDPC subcarrier mapping distance parameter D_TM (because 208 / 26=8), and the IM pilot index is set to 1, 10, 19, 28, etc. (ignoring guard subcarriers, CFO pilot subcarriers, etc.).

[0042] More specifically, for Figure 4 In the example shown, eight CFO pilots are used with the following predefined index set: {–116, –90, –48, –22, 22, 48, 90, 116}. 26 IM pilots are also predefined by the following index set: {–122 –112 –103 –94 –84 –75 –66 –57 –47 –38 –29 –19 –10 2 11 20 30 39 49 58 67 76 85 95 104 113}. After LDPC subcarrier mapping, the remaining 242 – 26 – 8 = 208 indices are used for data. Therefore, according to the embodiment of AP110 or one or more non-AP sites 120, 208 data QAMs provided by block 401 are input into LDPC TM402, wherein these data QAMs are interleaved with the LDPC subcarrier mapping distance parameter D_TM having a value of 8, such that in the output, two consecutive QAMs are spaced 8 subcarriers apart (in a cyclic manner). That is, the first QAM is located on the first physically available subcarrier, the second QAM is located on the ninth available subcarrier, and so on. Of the 256 subcarriers (in a 20 MHz PPDU), 6 subcarriers are used for left-side protection, 5 subcarriers are used for right-side protection, and 3 subcarriers are used as DC subcarriers (all unused), so 256 – 6 – 5 – 3 = 242 subcarriers are available for data, CFO, and IM pilots, wherein, as described above, the data QAMs are mapped to those subcarriers in the 242-tone RU that are not reserved for CFO or IM pilots. In this case, the index of the 256 frequency subcarriers in the input buffer of IDFT / FFT is {–128…127}, adopting the same convention as future communication networks according to IEEE 802.11.

[0043] In another embodiment, for a 484-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 52 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–244 –234 –225 –216 –206 –197 –188 –179 –169 –160 –151 –141 –132 –123 –114 –105 –95 –86 –76 –67 –58 –49 –40 –30 –21 –12 3 13 22 31 41 50 59 68 77 87 96 106 115 124 133 142 152 161 171 180 189 198 207 217 226 235}. In this embodiment, LDPC TM 402 can use a value of 8 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend the data QAM in frequency. When 52 IM pilots (before the data QAM) are inserted into LDPC TM 202 using D_TM=9, the result is the same as described above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0044] In another embodiment, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 maps 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indices: {–500 –490 –480 –470 –459 –449 –439 –429 –419 –409 –398 –388 –378 –368 –358 –348 –338 –327 –317 –307 –297 –287 –277 –267 –256 –246 –236 –226 –215 –205 –195 –185 –175 –165 –155 –144 –134 –124 –114 –104 –94 –83 –73 –63 –53 –43 –33 –23 –12 3 13 24 34 44 54 64 74 84 95 105 115 125 135 145 156 166 176 186 196 206 216 227 237 247 257 268 278 288 298 308 318 328 339 349 359 369 379 389 399 410 420 430 440 450 460 471 481 491}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend data QAM in frequency. When 98 IM pilots (before the data QAM) are inserted into an LDPC TM 202 using D_TM=10, the same result as described above is generated. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0045] For a RU with more than 996 subcarriers, AP 110 or one or more non-AP sites 120 can be used to apply the same index as defined above for a 996-tone RU to a portion of the RU (e.g., for a 2x996-tone RU, the same index can be used for each component 996-tone RU).

[0046] When the IM pilot is inserted into the LDPC TM 202 as a consecutive block group arranged before the data QAM block group, the embodiments described above for 242-tone RU, 484-tone RU, and 996-tone RU provide the same functionality as described above. Figure 2 and Figure 3The results are the same as those described in the context of the LDPC TM method. Several other embodiments will be described below that provide the same results as the LDPC TM method when IM pilots are inserted into the LDPC TM 202 as consecutive blocks following data QAM blocks. For example, for a 242-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 according to another embodiment is used to map 26 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indices: {–113 –104 –95 –85 –76 –67 –58 –49 –39 –30 –20 –11 –2 1019 29 38 47 57 66 75 84 94 103 112 122}. In this embodiment, LDPC TM 402 can use the value 8 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend the data QAM in frequency. When 26 IM pilots (after data QAM) are inserted into the input buffer of the LDPC TM 202 and operated on using D_TM=9, the following results are generated: Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0047] In another embodiment, for a 484-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 52 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {-235-226-217-207-198-189-180-171-161-152-142-133-124-115-106-96-87-77-68-59-50-41-31-22-13-3 12 21 30 40 49 58 67 76 86 95 105114 123 132 141 151 160 169 179 188 197 206 216 225 234 244}. In this embodiment, LDPC TM 402 can use a value of 8 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend the data QAM in frequency. When 52 IM pilots (after the data QAM) are inserted into LDPC TM 202 using D_TM=9, the result is the same as described above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0048] In another embodiment, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: { –491 –481 –471 –460 –450 –440 –430 –420 –410 –399 –389 –379 –369 –359 –349 –339 –328 –318 –308 –298 –288 –278 –268 –257 –247 –237 –227 –216 –206 –196 –186 –176 –166 –156 –145 –135 –125 –115 –105 –95 –84 –74 –64 –54 –44 –34 –24 –13 –3 12 23 33 43 53 63 73 83 94 104 114 124 134 144 155 165 175 185 195 205 215 226 236 246 256 267 277 287 297 307 317 327 338 348 358 368 378 388 398 409 419 429 439 449 459 470 480 490 500}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend data QAM in frequency. When 98 IM pilots (after data QAM) are inserted into an LDPC TM 202 using D_TM=10, the same results as described above will occur. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0049] In the following sections, several additional embodiments of the frequency mapper 403 for AP 110 or one or more non-AP sites 120 are described for different RU sizes. These embodiments (as described above) are implemented to achieve the same results as those described above. Figure 2 and Figure 3 The same results are obtained from the LDPC™ method described in the context of the above, i.e., the same data and IM pilot indexes. The main feature of the embodiments described below is that the distribution of the IM pilots is (nearly) symmetrical, i.e., with an offset, or completely symmetrical, i.e., without frequency offset under the operation of reflection around its origin (i.e., around the DC subcarrier).

[0050] For example, for a 242-tone RU, according to another embodiment, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 26 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–118 –108 –99 –89 –80 –71 –62 –53 –43 –34 –25 –15 –6 6 15 25 34 43 5362 71 80 89 99 108 118}. In this embodiment, LDPC TM 402 can use the value 8 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend the data QAM in frequency. When 26 IM pilots (before the data QAM) are inserted into LDPC TM 202 using D_TM=9 and shifted by 4x26-tone RU, the result is similar to the above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0051] In another embodiment, for a 484-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 52 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–240 –230 –221 –211 –202 –193 –184 –175 –165 –156 –147 –137 –128 –119 –110 –100 –91 –82 –72 –63 –54 –45 –35 –26 –17 –7 7 17 26 35 45 54 63 72 82 91 100 110 119 128 137 147 156 165 175 184 193 202 211 221 230 240}. In this embodiment, LDPC TM 402 can use a value of 8 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend the data QAM in frequency. When 52 IM pilots (before the data QAM) are inserted into LDPC TM 202 using D_TM=9 and shifted by 4x52-tone RU, the result is the same as described above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0052] In another embodiment, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–496 –486 –476 –465 –455 –445 –435 –425 –415 –405 –394 –384 –374 –364 –354 –344 –333 –323 –313 –303 –293 –283 –273 –262 –252 –242 –232 –222 –211 –201 –191 –181 –171 –161 –150 –140 –130 –120 –110 –100 –90 –79 –69 –59 –49 –39 –29 –19 –8 7 17 28 38 48 58 68 78 89 99 109 119 129 139 149 160 170 180 190 200210 221 231 241 251 261 272 282 292 302 312 322 332 343 353 363 373 383 393404 414 424 434 444 454 464 475 485 495}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend data QAM in frequency. When 98 IM pilots with 4x98 data subcarrier shifts are inserted into an LDPC TM 202 using D_TM=10, the result is similar to the one described above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0053] According to the variant, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–495 –485 –475 –464 –454 –444 –434 –424 –414 –404 –393 –383 –373 –363 –353 –343 –332 –322 –312 –302 –292 –282 –272 –261 –251 –241 –231 –221 –210 –200 –190 –180 –170 –160 –149 –139 –129 –119 –109 –99 –89 –78 –68 –58 –48 –38 –28 –17 –78} 19 29 39 49 59 69 79 90 100 110 120 130 140 150 161 171 181 191 201 211 222232 242 252 262 273 283 293 303 313 323 333 344 354 364 374 384 394 405 415 425 435 445 455 465 476 486 496}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM to extend data QAM in frequency. When 98 IM pilots with 5x98 data subcarrier shifts are inserted into an LDPC TM 202 using D_TM=10, the result is similar to the one described above. Figure 2 and Figure 3 The results are the same as those described in the context of the LDPC™ method, i.e., the same data and IM pilot index.

[0054] In another embodiment, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 maps 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–495 –485 –475 –464 –454 –444 –434 –424 –414 –404 –393 –383 –373 –363 –353 –343 –332 –322 –312 –302 –292 –282 –272 –261 –251 –241 –231 –221 –210 –200 –190 –180 –170 –160 –149 –139 –129 –119 –109 –99 –89 –78 –68 –58 –48 –38 –28 –17 –7 7} 17 28 38 48 58 68 78 89 99 109 119 129 139 149 160 170 180 190 200210 221 231 241 251 261 272 282 292 302 312 322 332 343 353 363 373 383 393404 414 424 434 444 454 464 475 485 495}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM, i.e., D_TM=9, to extend data QAM in frequency. This yields the same result as inserting 98 IM pilots before the data QAM, shifting by 4.5x98-tone, and using D_TM=10, i.e., the same data and IM pilot indexes.

[0055] In another embodiment, for a 996-tone RU, the frequency mapper 403 of AP 110 or one or more non-AP sites 120 is used to map 98 IM pilot subcarriers to subcarriers based on the following predefined set of IM pilot subcarrier indexes: {–496 –486 –476 –465 –455 –445 –435 –425 –415 –405 –394 –384 –374 –364 –354 –344 –333 –323 –313 –303 –293 –283 –273 –262 –252 –242 –232 –222 –211 –201 –191 –181 –171 –161 –150 –140 –130 –120 –110 –100 –90 –79 –69 –59 –49 –39 –29 –19 –8 8 19 29 39 49 59 69 79 90 100 110 120 130 140 150 161 171 181 191 201211 222 232 242 252 262 273 283 293 303 313 323 333 344 354 364 374 384 394405 415 425 435 445 455 465 476 486 496}. In this embodiment, LDPC TM 402 can use the value 9 for the predefined LDPC subcarrier mapping distance parameter D_TM, i.e., D_TM=9, to extend data QAM in frequency. This produces the same result as inserting the first 49 IM pilots out of a total of 98 IM pilots and shifting them by 4x98-tone, and inserting the last 49 IM pilots out of a total of 98 IM pilots and shifting them by 5x98-tone, and using D_TM=10, i.e., the same data and IM pilot indices—all relative to the pilots that are (logically) placed at the beginning before the data.

[0056] In one embodiment, the LDPC™ 402 of the AP or one or more non-AP sites 120 is used to, based on one or more predefined CFO pilot subcarrier index sets (i.e., one or more predefined frequency subcarrier index sets dedicated to CFO pilot subcarriers) defined by the current or future IEEE 802.11 standard framework, to Figure 4Box 405 in the diagram provides the CFO pilot mapping to subcarriers. More specifically, for a 242-tone RU in a 20 MHz bandwidth, the predefined CFO pilot subcarrier index set includes {–116, –90, –48, –22, 22, 48, 90, 116}. These index values ​​correspond to {13 39 81 107 151 177 219 245} – 129, where the values ​​13, 29, ... correspond to values ​​starting from index 1 (for the leftmost subcarrier). Given an FFT size of 256 in a 20 MHz bandwidth, subtracting 129 positions the DC subcarrier at position 0. For a 484-tone RU in a 40MHz bandwidth, the predefined CFO pilot subcarrier index set includes the following 16 indices: {–238, –212, –170, –144, –104, –78, –36, –10, 10, 36, 78, 104, 144, 170, 212, 238}. These values ​​correspond to {19 45 87 113 153 179 221 247 267 293 335 361 401 427 469 495} –257, where the values ​​19, 45, ... correspond to indices starting from 1 (for the leftmost subcarrier). Given an FFT size of 512 in a 40MHz bandwidth, subtracting 257 positions the DC subcarrier at position 0. For a 996-tone RU in an 80 MHz bandwidth, the predefined CFO pilot subcarrier index set includes the following indices: {468, -400, -334, -266, -220, -152, -86, -18, 18, 86, 152, 220, 266, 334, 400, 468}. These values ​​correspond to {45 113 179 247293 361 427 495 531 599 665 733 779 847 913 981} – 513, where the values ​​45, 113, ... correspond to indices starting from 1 (for the leftmost subcarrier). Given an FFT size of 1024 in an 80 MHz bandwidth, subtracting 513 positions the DC subcarrier at position 0.

[0057] As will be understood, there are some inherent differences between CFO and IM pilots. CFO pilots have a predefined index that maps the CFO pilot directly to its physical location in the frequency (subcarrier), and this is defined by the IEEE 802.11 standard framework, ensuring that the location of the CFO pilot is frequency-symmetric. Furthermore, the CFO is "single-stream," meaning its content is identical for all streams. To enable the receiver to calculate the covariance of multi-stream interference signals, IM pilots can be used with "multi-stream" content (different content for each stream). CFO pilots are used to estimate and correct the CFO between the transmitter and receiver. For this, only a few CFO pilots are needed (as mentioned above, 8 CFO pilots are defined for a 242-tone RU and 16 CFO pilots are defined for a 484 / 996-tone RU). However, to estimate and mitigate interference, whether broadband or narrowband, a significantly larger number of IM pilots are typically required, such as approximately 10% of the subcarriers of the RU.

[0058] Figure 5 A more detailed transmission processing chain, implemented by AP 110 (or one or more similar non-AP sites 120), is shown for an embodiment of LDPC-encoded data transmission as defined by the current or future IEEE 802.11 standard framework. Bits from the MAC layer undergo FEC pre-padding in box 501 (if applicable), scrambling in box 503, encoding using LDPC encoder 505, and FEC post-padding in box 506. If multiple spatial streams are used, the FEC post-padding bits are partitioned between the spatial streams by stream resolver 507 and then fed to the corresponding constellation mapper 401, which applies a constellation mapping process (e.g., QAM) to the bit streams. As described above, the resulting modulation symbols (specifically QAM symbols) are interleaved, i.e., frequency-permuted using LDPC™ 402 (for each spatial stream), followed by spatial mapping (e.g., beamforming), then mapped to subcarriers by frequency mapper 403, and subsequently sampled in the time domain by IDFT / IFFT operations applied in box 515. Finally, the corresponding CP can be inserted through box 517, and other analog and RF boxes (not shown) can generate the actual antenna feed signal based on the output from the preceding boxes, used to generate the RF transmission of the PPDU to one or more receivers. As described above... Figure 4As described in the context, frequency mapper 403 is used to map multiple IM pilot subcarriers to multiple frequency subcarriers of the RU based on a predefined IM pilot subcarrier index set and to map multiple CFO pilot subcarriers to multiple additional frequency subcarriers of the RU based on a predefined CFO pilot subcarrier index set (i.e., a predefined frequency subcarrier index set dedicated to CFO pilot subcarriers), and to insert the IM pilots provided by block 404 and the CFO pilots provided by block 405 into the RU.

[0059] Figure 6 A flowchart illustrating the steps of a method 600 for operating a WLAN site (e.g., AP 110) to communicate with another WLAN site (e.g., one or more non-AP sites 120) within WLAN 100 is shown. As described above, the WLAN site (e.g., AP 110) is used to communicate with another WLAN site (e.g., one or more non-AP sites 120) using an interference mitigation (IM) operating mode, wherein, in IM mode, AP 110 is used to send physical protocol data units (PPDUs) to one or more non-AP sites 120, wherein the PPDUs are based on resource units (RUs). Method 600 includes step 601, which involves permuting multiple data subcarriers of the RU to obtain multiple permuted data subcarriers of the RU. Furthermore, method 600 includes step 603, which involves mapping multiple IM pilot subcarriers onto multiple frequency subcarriers of the RU based on a predefined IM pilot subcarrier index set, wherein the predefined IM pilot subcarrier index set depends on the size of the RU. Method 600 further includes step 605, which maps the plurality of permuted data subcarriers onto the plurality of remaining frequency subcarriers of the RU. In one embodiment, method 600 may further include an initial step, which allocates a subset of the plurality of subcarriers of the RU as data subcarriers for carrying modulated data.

[0060] Those skilled in the art will understand that “blocks” (“units”) in the various figures (methods and apparatuses) represent or describe the functionality of embodiments of the invention (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.

[0061] 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 embodiments of the apparatus are merely exemplary. For example, the unit division is only a logical functional division, and other division methods may be used in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not performed. Furthermore, 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.

[0062] The units described as separate parts may or may not be physically separate. The parts shown as units may or may not be physical units, and may be located in one location or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0063] In addition, the functional units in the embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

Claims

1. A wireless local area network (WLAN) station (110; 120), characterized by The WLAN stations (110; 120) are used to incorporate dedicated interference mitigation (IM) pilots into transmitted physical protocol data units (PPDUs). The WLAN stations (110; 120) include a low-density parity check (LDPC) subcarrier mapper (202), which is used to frequency-spread the interference mitigation (IM) pilots and data quadrature amplitude modulation (QAM), wherein the data QAM is a QAM-enhanced data subcarrier. The WLAN stations (110; 120) are used for: Before applying the subcarrier mapping operation, the insertion of the dedicated IM pilot is performed at the input of the LDPC mapper 202.

2. The WLAN station (110; 120) according to claim 1, characterized in that, The LDPC subcarrier mapper is also used to interleave its input in frequency based on the LDPC subcarrier mapping distance parameter D_TM. The input of the LDPC subcarrier mapper includes the dedicated IM pilot and the data QAM. The D_TM depends on the size of the resource unit (RU) of the PPDU.

3. The WLAN station (1 10; 120) according to claim 1 or 2, characterized in that The D_TM is equal to the number of data subcarriers N_SD included in the RU of the PPDU divided by the number of dedicated IM pilots N_SD_IM, where N_SD is an integer multiple of N_SD_IM.

4. The WLAN station (110; 120) according to any one of claims 1-3, characterized in that, The RU of the PPDU includes a data subcarrier, and the RU of the PPDU also includes a subcarrier for carrier frequency offset (CFO) pilot.

5. The WLAN site (110; 120) according to any one of claims 1-4, characterized in that, In the scenario where the RU of the PPDU is a 242-tone RU, the 242-tone RU includes 8 subcarriers for CFO pilots and 234 data subcarriers. The 234 data subcarriers are used for the data QAM and the dedicated IM pilots. The number of dedicated IM pilots is 26, the number of data QAMs is 208, and the LDPC subcarrier mapping distance parameter D_TM of the LDPC subcarrier mapper is equal to 9. If the 26 dedicated IM pilots are inserted into the LDPC subcarrier mapper (202) as a continuous block group before the data QAM, then the index of the 26 dedicated IM pilots includes at least {1, 10, 19, 28}, where 1 corresponds to the first index.

6. The WLAN station (110; 120) according to any one of claims 1-4, characterized in that, In the scenario where the RU of the PPDU is 484-tone RU, the number of dedicated IM pilots is 52. The 52 dedicated IM pilots are inserted as a continuous block group into the LDPC subcarrier mapper (202) before the data QAM. The LDPC subcarrier mapping distance parameter D_TM of the LDPC subcarrier mapper is equal to 9. The index of the 52 dedicated IM pilots includes at least {1, 10, 19, 28}, where 1 corresponds to the first index.

7. A method of a wireless local area network (WLAN) station (110; 120) to communicate with another WLAN station (120; 110) in a WLAN (100), characterized in that, The WLAN stations (110; 120) are used to incorporate dedicated interference mitigation (IM) pilots into transmitted physical protocol data units (PPDUs). The WLAN stations (110; 120) include a low-density parity check (LDPC) subcarrier mapper (202), which is used to frequency-spread the interference mitigation (IM) pilots and data quadrature amplitude modulation (QAM), wherein the data QAM is a QAM-enhanced data subcarrier. The method includes: Before applying the subcarrier mapping operation, the insertion of the dedicated IM pilot is performed at the input of the LDPC mapper 202.

8. The method according to claim 7, characterized in that, The LDPC subcarrier mapper is also used to interleave its input in frequency based on the LDPC subcarrier mapping distance parameter D_TM. The input of the LDPC subcarrier mapper includes the dedicated IM pilot and the data QAM. The D_TM depends on the size of the resource unit (RU) of the PPDU.

9. The method according to claim 7 or 8, characterized in that, The D_TM is equal to the number of data subcarriers N_SD included in the RU of the PPDU divided by the number of dedicated IM pilots N_SD_IM, where N_SD is an integer multiple of N_SD_IM.

10. The method according to any one of claims 7-9, characterized in that, The RU of the PPDU includes a data subcarrier, and the RU of the PPDU also includes a subcarrier for carrier frequency offset (CFO) pilot.

11. The method according to any one of claims 7-10, characterized in that, In the scenario where the RU of the PPDU is a 242-tone RU, the 242-tone RU includes 8 subcarriers for CFO pilots and 234 data subcarriers. The 234 data subcarriers are used for the data QAM and the dedicated IM pilots. The number of dedicated IM pilots is 26, the number of data QAMs is 208, and the LDPC subcarrier mapping distance parameter D_TM of the LDPC subcarrier mapper is equal to 9. If the 26 dedicated IM pilots are inserted into the LDPC subcarrier mapper (202) as a continuous block group before the data QAM, then the index of the 26 dedicated IM pilots includes at least {1, 10, 19, 28}, where 1 corresponds to the first index.

12. The method according to any one of claims 7-10, characterized in that, In the scenario where the RU of the PPDU is 484-tone RU, the number of dedicated IM pilots is 52. The 52 dedicated IM pilots are inserted as a continuous block group into the LDPC subcarrier mapper (202) before the data QAM. The LDPC subcarrier mapping distance parameter D_TM of the LDPC subcarrier mapper is equal to 9. The index of the 52 dedicated IM pilots includes at least {1, 10, 19, 28}, where 1 corresponds to the first index.

Images