Method and apparatus for low power indoor frame format

Abstract

Methods and apparatuses for encoding and decoding a physical layer (PHY) protocol data unit (PPDU) for low power indoor (LPI) wireless communication, the PPDU including a preamble portion and a payload portion. The preamble portion includes a first universal signal field (U-SIG), the first U-SIG including information about the payload portion of the PPDU. The preamble portion also includes a second U-SIG, the second U-SIG including the same information about the payload portion of the PPDU. The repeated U-SIG can improve the robustness of preamble portion detection and also enable automatic detection of the PPDU for LPI communication.

Description

[0001] Cross-referencing related applications

[0002] This application claims the benefit and priority of U.S. non-provisional patent application No. 17 / 403,521, filed August 16, 2021, entitled "Low Power Indoor Frame Form," and U.S. provisional patent application No. 63 / 069,556, filed August 24, 2020, entitled "Low Power Indoor Frame Form," the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to methods and systems for wireless network communication, and more specifically, to methods and apparatus for Low Power Indoor (LPI) frame formats. Background Technology

[0004] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is a set of media access control (MAC) and physical layer (PHY) specifications for enabling wireless local area network (WLAN) communication in the Wi-Fi band. The 802.11 standard has undergone steady development and is expected to continue to grow to meet the increasing demands for enhanced throughput, reduced latency and jitter, higher reliability, and improved energy efficiency driven by emerging applications including virtual or augmented reality, immersive gaming, remote work, and cloud computing.

[0005] The IEEE 802.11 Task Force (TGbe) is currently developing a new protocol, IEEE 802.11be, which will be the next major IEEE 802.11 revision to define next-generation Wi-Fi, following IEEE 802.11ax (IEEE Standard 802.11ax-2021). IEEE 802.11be (also known as Extremely High Throughput (EHT)) is expected to support data rates of at least 30 Gbps and can use up to 320 MHz of spectrum bandwidth for unlicensed operation, double the maximum 160 MHz bandwidth currently envisioned for IEEE 802.11ax. This increased capability of 802.11be is at least partly attributable to the release of the 6 GHz band for unlicensed use.

[0006] The ability of low-power indoor (LPI) devices to operate across the entire 6 GHz band is fundamental to the success of 6 GHz development. Due to their low power and indoor operation, these devices do not require Automatic Frequency Coordination (AFC) and can operate in all four sub-bands while protecting licensed operations.

[0007] However, the effective isotropically radiated power (EIRP) power spectral density (PSD) requirements for LPI APs and STAs in the 6 GHz band are significantly higher than those in the 2.4 GHz and 5 GHz bands. For example, the maximum allowed EIRP PSD for a 6 GHz LPI AP is 5 dBm / MHz, while that for a 5 GHz LPI AP is 17 dBm / MHz; the maximum allowed EIRP PSD for a 6 GHz LPI STA is -1 dBm / MHz, while that for a 5 GHz LPI STA is 11 dBm / MHz. Therefore, 6 GHz LPI APs and STAs have a smaller range (approximately one-quarter) and less coverage (approximately 1 / 16) than 5 GHz LPI APs and STAs.

[0008] In response, a novel wide-bandwidth (BW) LPI long-range (LR) PPDU has been proposed to improve the aforementioned range and coverage issues. Specifically, a duplication (DUP) mode has been proposed to extend the transmission range of LPI Wi-Fi systems in the 6 GHz band by enhancing the reliable detection of the payload portion of the LPI frame, as described in more detail below. However, the proposed DUP mode is defined only for the payload portion of the LPI frame, while the preamble portion, containing important control signals, remains unchanged. Therefore, the detection of the preamble portion becomes less reliable than that of the payload portion, and in some cases, the transmitted frame may fail due to a failure in the preamble portion, even though the payload is detectable. Furthermore, the LPI frame indicator is encoded into the preamble and may require the receiver to combine it to identify the incoming LPI frame, making automatic detection impossible.

[0009] Therefore, it is desirable to provide an LPI frame format that can provide the same or more robust preamble as the payload portion of an LPI frame, and that allows for automatic detection of LPI frames. Summary of the Invention

[0010] An exemplary implementation of this disclosure provides an LPI frame format that has a preamble that is more robust than the payload and enables the receiver to automatically detect LPI frames.

[0011] In some aspects, this disclosure describes a method for encoding a physical layer (PHY) protocol data unit (PPDU) for low power indoor (LPI) wireless communication, the method comprising: encoding a preamble portion of the PPDU, wherein the encoding further comprises: encoding a first universal signal field (U-SIG), wherein the first U-SIG includes one or more information bits relating to a payload portion of the PPDU; and encoding at least a second U-SIG, the second U-SIG including the same one or more information bits relating to the payload portion of the PPDU.

[0012] In any of the foregoing aspects, the second U-SIG can be encoded after the first U-SIG has been encoded.

[0013] Any of the foregoing aspects may further include encoding a plurality of U-SIGs in addition to the first U-SIG and the second U-SIG, wherein each of the plurality of U-SIGs includes the same one or more information bits relating to the payload portion of the PPDU.

[0014] Any of the foregoing may further include applying dual sub-carrier modulation (DCM) to the second U-SIG.

[0015] Any of the foregoing may also include: applying a bit-by-bit interleaver scheme to the second U-SIG.

[0016] In any of the foregoing aspects, the first U-SIG and the second U-SIG are encoded using a modulation and coding scheme (MCS) with a code rate greater than 0.5. The method further includes: applying a first binary convolution code (BCC) puncturing pattern to the first U-SIG; and applying a second BCC puncturing pattern to the second U-SIG, wherein the second BCC puncturing pattern is different from the first BCC puncturing pattern.

[0017] In any of the foregoing aspects, the LPI wireless communication can be defined for extended range operation modes.

[0018] In any of the foregoing aspects, the extended range operating mode can be defined for an MCS scheme for MCS0, which uses a single spatial stream in a non-puncturing channel having one of a bandwidth of 80 MHz, 160 MHz, and 320 MHz for a single station (STA).

[0019] In some other aspects, this disclosure describes an access point (AP) apparatus comprising a non-transitory memory storage unit and a processing unit operatively coupled to the non-transitory memory storage unit, the processing unit being configured to: encode a preamble portion of a PPDU for low-power indoor (LPI) wireless communication, wherein the preamble portion of the PPDU includes: a first universal signal field (U-SIG) including one or more information bits relating to a payload portion of the PPDU; at least a second U-SIG including the same one or more information bits relating to the payload portion of the PPDU; and transmit the encoded PPDU.

[0020] In any of the above-described aspects of the apparatus, in addition to the first U-SIG and the second U-SIG, the preamble portion may also include a plurality of U-SIGs, wherein each of the plurality of U-SIGs includes the same one or more information bits relating to the payload portion of the PPDU.

[0021] In any of the above-described aspects of the apparatus, the processing unit may apply the DCM scheme to the second U-SIG.

[0022] In any of the above-described aspects of the apparatus, the processing unit may apply a bit-by-bit interleaver scheme to the second U-SIG.

[0023] In any of the above-described apparatus aspects, the first U-SIG and the second U-SIG may be encoded using a modulation and coding scheme (MCS) with a code rate greater than 0.5, wherein the processing unit applies a first binary convolution code (BCC) puncturing pattern to the first U-SIG; and the processing unit applies a second BCC puncturing pattern to the second U-SIG, wherein the second BCC puncturing pattern is different from the first BCC puncturing pattern.

[0024] In some other aspects, this disclosure describes an apparatus for a station (STA), wherein the apparatus includes a non-transitory memory storage unit and a processing unit operatively coupled to the non-transitory memory storage unit, the processing unit being configured to: receive a preamble portion of a PPDU, wherein the detection further includes: detecting a first universal signal field (U-SIG) in the preamble portion of the PPDU, the first U-SIG including one or more information bits relating to a payload portion of the PPDU; detecting at least a second U-SIG, the second U-SIG including the same one or more information bits relating to the payload portion of the PPDU; combining the first U-SIG and the second U-SIG; and decoding the preamble portion of the PPDU based on the combined first U-SIG and second U-SIG.

[0025] In any of the above-described aspects of the apparatus, before combining the first U-SIG and the second U-SIG, the processing unit may be configured to: perform a correlation check between the first U-SIG and the second U-SIG; and, if positively correlated, automatically determine that the PPDU is configured for low-power indoor (LPI) wireless communication.

[0026] In any of the above-described aspects of the apparatus, the automatic determination of the PPDU may further include the automatic determination of the MCS scheme of MCS0, the MCS scheme of MCS0 using a single spatial stream in a non-puncturing channel having one of a bandwidth of 80 MHz, 160 MHz, and 320 MHz for a single station (STA).

[0027] In any of the above-described apparatus aspects, in addition to the first U-SIG and the second U-SIG, the preamble portion may also include a plurality of U-SIGs, and the processing is further configured to combine the plurality of U-SIGs with the first U-SIG and the second U-SIG to improve the robustness of the detection of the preamble portion.

[0028] In any of the above-described aspects of the apparatus, the processing unit may also be configured to decode a second U-SIG to which the DCM scheme is applied.

[0029] In any of the above-described apparatus aspects, the first U-SIG and the second U-SIG in the preamble portion of the received PPDU can be encoded using a modulation and coding scheme (MCS) with a code rate greater than 0.5, and the processing unit is further configured to: detect the first U-SIG having a first binary convolution code (BCC) puncturing pattern; and detect the second U-SIG having a second BCC puncturing pattern, wherein the second BCC puncturing pattern is different from the first BCC puncturing pattern.

[0030] In other aspects, this disclosure describes a method for encoding a physical layer (PHY) protocol data unit (PPDU) for low power indoor (LPI) wireless communication, the method comprising: encoding a preamble portion of the PPDU, wherein the encoding further comprises: encoding a first universal signal field (U-SIG), the first U-SIG comprising one or more information bits relating to a payload portion of the PPDU, wherein the preamble portion does not contain an Extremely High Throughput (EHT) signal field (SIG). Attached Figure Description

[0031] The accompanying drawings, which now illustrate exemplary embodiments of this application, will be shown by way of example, and in the drawings:

[0032] Figure 1 A wireless network comprising multiple wireless communication devices configured to transmit and receive wireless signals, according to an example embodiment, is shown.

[0033] Figure 2 It shows that it can serve as Figure 1Example wireless communication devices of AP 102 or STA 104 shown;

[0034] Figure 3 shows an example of a prior art EHT PPDU frame that can be used for wide BW LPI LR communication in an 80MHz channel;

[0035] Figure 4 A simulation diagram is shown, illustrating the improvement of MSC0 with the application of the DCM scheme;

[0036] Figure 5 An EHT LPIPPDU according to an embodiment of this disclosure is shown;

[0037] Figure 6 Another embodiment of the EHT LPIPPDU according to the present disclosure is shown;

[0038] Figure 7 Another embodiment of the EHT LPIPPDU according to the present disclosure is shown; and

[0039] Figure 8 Another embodiment of the EHT LPIPPDU according to the present disclosure is shown. Detailed Implementation

[0040] For the purpose of illustration, specific exemplary embodiments will be described in more detail below with reference to the accompanying drawings.

[0041] The embodiments described herein represent information sufficient to practice the claimed subject matter and illustrate methods for practicing such subject matter. Upon reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of the claimed subject matter and will recognize that the application of these concepts is not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

[0042] Furthermore, it should be understood that any module, component, or device disclosing the executable instructions herein may include or otherwise access one or more non-transitory computer / processor-readable storage media to store information, such as computer / processor-readable instructions, data structures, program modules, and / or other data. A non-exhaustive list of examples of non-transitory computer / processor-readable storage media includes: magnetic tape cassettes; magnetic tape; disk storage or other magnetic storage devices; optical discs such as compact disc read-only memory (CD-ROM); digital video discs or digital multifunction discs (i.e., DVDs); and Blu-ray discs. TM; or other optical storage; volatile and non-volatile, removable and non-removable media implemented in any method or technology; random-access memory (RAM); read-only memory (ROM); electrically erasable programmable read-only memory (EEPROM); flash memory or other storage technologies. Any such non-transitory computer / processor storage medium may be part of a device or accessible to or connected to that device. Computer / processor-readable / executable instructions used to implement the applications or modules described herein may be stored by or otherwise preserved by such non-transitory computer / processor-readable storage media.

[0043] The following is a partial list of abbreviations and associated definitions that may be used in the description below:

[0044] DUP Copy

[0045] LPI Low Power Indoor

[0046] U-SIG General SIG Field

[0047] EHT Enhanced High Throughput

[0048] MCS modulation and coding scheme

[0049] DCM dual-carrier modulation

[0050] PPDU PLCP Protocol Data Unit

[0051] PLCP PHY Convergence Protocol

[0052] BW bandwidth

[0053] This document describes a suitable LPI frame format for improving the robustness of the preamble of an LPI frame, making it equal to or greater than the robustness of the payload portion. This description also describes example implementations of an LPI frame format that allow a receiver to automatically detect incoming LPI frames. The example implementations described herein can be implemented using IEEE 802.11 technology.

[0054] Figure 1 A wireless network 100 comprising a plurality of wireless communication devices configured to transmit and receive wireless signals is illustrated according to an example embodiment. The wireless network 100 may be a wireless local area network (WLAN), but the embodiment is not limited thereto.

[0055] The wireless communication equipment includes an access point (AP) 102 and a station (STA) 104. In some embodiments, AP 102 and STA 104 may be configured to transmit and receive signals within the wireless network 100 according to specific communication standards and / or protocols, such as any standard in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, which includes IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ax, and / or WLAN recommendations such as IEEE 802.11be. Communication within the wireless network 100 may also be adapted to transmit and / or receive communication according to other technologies and standards, including the Long-Term Evolution (LTE) standard issued by the Third Generation Partnership Project (3GPP). In other examples, the wireless standard may include the Fifth Generation (5G) wireless standard.

[0056] In some examples, wireless network 100 can be configured for very high throughput (VHT) communication according to the IEEE 802.11ac standard (hereinafter referred to as the 11ac standard), high efficiency (HE) communication according to the IEEE 802.11ax standard (hereinafter referred to as the 11ax standard), or extremely high throughput (EHT) communication according to the proposed IEEE 802.11be standard (hereinafter referred to as the 11be standard) or any other suitable wireless communication standard between AP 102 and STA 104. Wireless network 100 can be configured to employ orthogonal frequency-division multiple access (OFDMA) technology.

[0057] STA 104 can be associated with AP 102 through a registration process. Once associated, AP 102 can communicate with STA 104 in wireless network 100. In some implementations, STA 104 may be an LPI device primarily operating indoors, where signal transmission may be attenuated due to indoor structures such as walls. STA 104 can be any LPI electronic device primarily intended for indoor setup. For example, STA 104 may include any of the following: desktop computer, laptop computer, tablet computer, smartphone, Internet of Things (IoT) device (e.g., sensor, camera, thermostat, home appliance, etc.), wearable device (e.g., smartwatch, smart glasses, head-mounted device, etc.), server computer, storage device, etc.

[0058] In the example implementation, AP 102 is configured to act as an interface between STA 104 and network 106, wherein AP 102 can forward requests to network 106 via a bidirectional communication link and pass responses received from network 106 to STA 104 via a bidirectional wireless channel. In implementations where STA 104 is an LPI device, wireless communication between AP 102 and STA 104 may be attenuated due to indoor structural elements such as walls.

[0059] It should be understood that although a single instance of each AP 102, STA 104 and network 106 is shown, it is possible for multiple instances of each component to exist in the wireless network 100.

[0060] Figure 2 It shows that it can serve as Figure 1 The example wireless communication device shown is AP 102 or STA 104. The wireless communication device includes at least one processing unit 110, at least one transmitter 112, at least one receiver 114, one or more antennas 116, at least one non-transitory memory storage unit 118, and one or more input / output devices or interfaces 120.

[0061] Processing unit 110 implements various processing operations of AP 102 and receiver STA 104, such as signal encoding, data processing, power control, input / output processing, or any other functions. Processing unit 110 may also be configured to implement some or all of the functions and / or implementations described herein. Each processing unit 110 includes any suitable processing or computing device configured to perform one or more operations. For example, each processing unit 110 may include a microprocessor, microcontroller, digital signal processor, field-programmable gate array, or application-specific integrated circuit. Processing unit 110 is operatively connected to input 120, transmitter 112, and receiver 114, and can be configured to generate wireless signals based on signals received from input 120 for transmission by transmitter 112 or to process wireless signals received from receiver 114. In some implementations of transmitting OFDM or OFDMA signals, processing unit 110 may be configured to generate OFDM or OFDMA signals suitable for transmission by, for example, performing an inverse fast Fourier transform (IFFT) or any other suitable processing technique. Processing unit 110 may also be configured to process the received OFDM or OFDMA signal by, for example, performing a Fast Fourier Transform (FFT) or any other suitable processing technique. In some embodiments, processing unit 110 may be configured to detect the presence of an OFDM or OFDMA signal by performing correlation or cross-correlation to detect a preamble. The preamble may be part of a predetermined frame structure for Wi-Fi communication. Although a single instance of processing unit 110 is shown, it should be understood that multiple instances of processing unit 110 may exist in each wireless communication device. For example, at least one processing unit may be present for processing the output signal to be transmitted by transmitter 112 and at least one processing unit may be present for processing the input signal from receiver 114.

[0062] Transmitter 112 may include any suitable structure for generating signals for wireless or wired transmission. Each receiver 114 may include any suitable structure for processing wirelessly or wired received signals. Each transmitter 112 and receiver 114 may include associated amplification and modulation / demodulation circuitry. Although shown as separate components, at least one transmitter 112 and at least one receiver 114 may be combined into a single transceiver. Each antenna 116 may include any suitable structure for transmitting and / or receiving wireless or wired signals. Although a shared antenna 116 is shown herein coupled to both transmitter 112 and receiver 114, one or more antennas 116 may be coupled to one or more transmitters 112, and one or more individual antennas 116 may be coupled to one or more receivers 114. In some examples, one or more antennas 116 may be an antenna array that can be used for beamforming and beam control operations. Each non-transitory memory storage unit 118 may include any suitable volatile and / or non-volatile storage and retrieval device. Any suitable type of memory can be used, such as random access memory (RAM), read-only memory (ROM), hard disk, optical disk, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, etc. The non-transitory memory storage unit 118 can store instructions and data used, generated, or collected by AP 102 or STA 104. For example, the non-transitory memory storage unit 118 can store software instructions or modules configured to implement some or all of the functions and / or implementations described herein and executed by processing unit 110.

[0063] Input / output device / interface 120 may allow interaction with users or other devices on the network. Input / output device / interface 120 includes any suitable structure for providing information to or receiving / providing information from users, including network interface communication.

[0064] In some implementations, AP 102 and STA 104 can be configured to communicate over a variety of wireless channel bandwidths, including bandwidths with center frequencies of approximately 2.4 GHz, 5 GHz, and 6 GHz, as well as bandwidths of 20 MHz, 40 MHz or 80 MHz, 80+80 MHz, 160 MHz, 160+160 MHz, 320 MHz, 320+320 MHz, 480 MHz (e.g., 160+160+160 MHz), and 640 MHz. In some implementations, channel bandwidths less than 20 MHz can be used. According to some wireless standards such as 11ax, OFDMA channels are subdivided into multiple resource units (RUs), where each RU consists of a set of consecutive subcarriers defined in the frequency domain. In the 11ax standard, RUs are defined based on RU sizes such as 26-subcarrier RUs, 52-subcarrier RUs, 106-subcarrier RUs, 242-subcarrier RUs, 484-subcarrier RUs, 996-subcarrier RUs, and 2×996-subcarrier RUs. While referring to 11ax, it should be noted that some implementation techniques or mechanisms according to this disclosure can be used in conjunction with other standards, including future generations or different standards of the IEEE 802.11 standard. Different RUs for an OFDMA channel can include subcarriers of different frequencies. Each RU is a subchannel of the OFDMA channel. Different RUs can be assigned to different STAs within a Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU). Each RU is used for one OFDM symbol for one STA. Within the assigned RUs, the MCS for each station is the same across all OFDM symbols within a PPDU (i.e., each station uses a single MCS). Within a PPDU, the MCS used by RUs at different stations can be different.

[0065] In the wireless network 100, wireless communication devices such as AP 102 and STA 104 communicate with each other through various well-defined frame structures. Frame structures such as PPDUs can be defined by… Figure 2The processing unit 110 of the wireless communication device shown generates the frame. In some embodiments, the frame structure can be configured to have the same bandwidth as the channel. The frame structure can be in the form of a PPDU, which may include a frame preamble portion and a payload portion. In some embodiments, different types of PPDUs may exist, which may have different fields and different PHY layers and / or different MAC layers. For example, single-user (SU) PPDU, multiple-user (MU) PPDU, LPIPDU, long-range (LR) SUPPDU, and trigger-based (TB) PPDU.

[0066] The 11be standard has proposed a wide-bandwidth LPI LR PPDU (hereinafter referred to as LPIPDU) operating in the 6 GHz band, which at least partially addresses the short-range and reduced coverage imposed on LPI devices by the proposed EIRP PSD requirements. Here, wide bandwidth can be defined as having a bandwidth equal to or greater than 80 MHz. Figure 3 shows an example of a proposed EHT PPDU frame 200 that can be used for wide-bandwidth LPI LR communication in an 80 MHz channel. The EHT PPDU frame 200 can be generated and transmitted by the transmitter's processor 110 and received and decoded by the receiver's processor 110. The EHT PPDU frame 200 may include a preamble portion 202, followed by a payload portion 204.

[0067] As shown in the figure, the preamble section 202 may include a conventional preamble section 206 and an EHT preamble section 210. The conventional preamble section 206, established first in the IEEE 802.11a standard (hereinafter referred to as the 11a standard), allows backward compatibility and coexistence with conventional IEEE 802.11 devices. The conventional preamble section 206 may include two ODFM symbols carrying a legacy short training field (L-STF) (not shown) and a legacy long training field (L-LTF) (not shown), respectively configured for frame detection and receiver synchronization. The next OFDM symbol of the conventional preamble section 206 may carry a legacy signal field (L-SIG) (not shown), which indicates which MCS is used for subsequent signals and the associated frame length. The L-SIG symbol is then repeated as RL-SIG (not shown), which may or may not have the opposite polarity to L-SIG. RL-SIG can be used to support coverage extensions such as 11ax and allows for reliable transmission when using a small RU size. The legacy preamble section 206 can be decoded by legacy Wi-Fi devices. For 802.11 standards after 11n, the MCS and frame length indicated in L-SIG can be token placeholders. Real values ​​for MCS, frame size, and other parameters can be transmitted with different symbols depending on the specific version. As an example, in 11ax, firstly, it repeats L-SIG as RL-SIG, indicating a length equal to one or two modulo three. Secondly, its High Efficiency (HE) signal field includes two OFDM symbols. The first is modulated with QBPSK, and the second with either BPSK or QBPSK. The result of the modulo operation combined with the BPSK / QBPSK selection determines one of four 11ax frame types.

[0068] In the illustrated embodiment, the EHT preamble portion 210 includes a U-SIG field 212, an EHT-SIG field 214, an EHT-STF field 216, and an EHT-LTF field 218.

[0069] In some implementations, the 11be standard and higher frame formats use a dual OFDM symbol-length universal SIG (U-SIG) 212, which may include information bits about the payload portion 204. The adoption of U-SIG 212 provides forward compatibility with future IEEE 802.11 standards. As can be understood, a two-symbol-length U-SIG 212 can have a maximum bit-carrying capacity of 42 bits. U-SIG 212 is similar to HE-SIG-A in an 11ax PPDU because it can contain version-independent information followed by version-dependent information. Version-independent information may include a 3-bit PHY format identifier, a 1-bit UL / DL flag, at least 6 bits of Basic Service Set (BSS) color, at least 7 bits of transmission (TX) opportunity (TXOP) duration, bandwidth, etc. Version-dependent information may include the number of EHT long training field symbols, mid-amble period, and space-time block coding flags, etc. U-SIG 212 can also be encoded using a separate error detection code (i.e., at least a 4-bit cyclic redundancy check (CRC) code) and a 6-bit tail. Furthermore, the presence of U-SIG 204 and other symbols such as L-SIG allows the receiver to distinguish between 11be and 11ax frames. For example, for 11be EHT transmissions, the L_LENGTH field in L-SIG can be set such that L_LENGTH modulo 3 equals 1, and bit B0 of U-SIG 212 can be set to 0, allowing the receiver to identify it as an EHT PPDU. In some implementations, U-SIG 212 can be encoded, interleaved, and mapped to a binary phase shift keying (BPSK) constellation at a code rate of R = 1 / 2 using MCS0.

[0070] In some example implementations, the EHT-SIG field 214 may store information other than that stored in the U-SIG field 212. The EHT-SIG field 214 may employ its own MCS, which differs from the data MCS, and may occupy a variable number of ODFM symbols, as indicated in the U-SIG field 212. In example implementations, the EHT-SIG field 214 may include common fields and user-specific fields. Common fields may contain information about the MCS, the number of spatial streams (NSS), encoding, the duration of the guard interval, and RU allocation, etc. User-specific fields may exist in multi-user (MU) frames and carry dedicated information for a single STA. For example, the EHT-SIG field 214 may include subfields for each of multiple STAs. Each STA subfield may include subfields specifying the following: a STA-ID that uniquely identifies the target STA, the RU assigned to the target STA, and the MCS used by each corresponding RU assigned to the target STA (e.g., MCS(i) for RU i; MCS(j) for RU j). In the example implementation, the MCS subfield can be populated with the MCS index value mapped to the specified MCS applied to the RU.

[0071] In some example implementations, the EHT short training field (STF) 216 and the EHT long training field (LTF) 218 ​​may follow the EHT-SIG field 214 and may serve the time- and frequency tuning of MIMO / OFDMA. In some implementations, EHT-STF 216 and EHT-LTF 218 are longer variants of the STF and LTF from the 11ax standard, which can achieve extended range and better channel estimation. In some wideband implementations with a channel bandwidth of 80 MHz or greater, the EHT-STF field 216 and the EHT-LTF field 218 are repeated every 20 MHz, such as... Figure 2 As shown. In some implementations, the phase of each 20MHz replica of the EHT-STF 216 and EHT-LTF 218 can be rotated to reduce the peak-to-average power ratio and enhance related performance.

[0072] In some example implementations, when using a wide bandwidth, the conventional preamble portion 206, the U-SIG field 212, and the EHT-SIG field 214 can be copied once every 20 MHz. Therefore, as shown, in an 80 MHz channel, the conventional preamble 202 is repeated four times to form conventional preambles 206A, 206B, 206C, and 206D; U-SIG fields 212A, 212B, 212C, and 212D; and EHT-SIG fields 214A, 214B, 214C, and 214D.

[0073] The payload portion 204 may include one or more fields in the form of OFDM symbols containing Physical Layer Convergence Protocol (PLCP) Service Data Units (PSDUs), which are data units sent down from the MAC layer for transmission in the wireless medium.

[0074] The DUP mode, designed to extend the distance and coverage of LPI devices, is defined as non-punctured 80MHz, 160MHz, and 320MHz PPDUs transmitted to a single STA. In DUP mode, half of the payload portion 204 of the channel bandwidth is replicated in the other half of the bandwidth. As an example, in the case of an 80MHz PPDU, the higher 40MHz of the payload portion 204 of the PPDU is replicated to the lower 40MHz; or, in the case of a 160MHz PPDU, the higher 80MHz is replicated to the lower 80MHz; or, in the case of a 320MHz PPDU, the higher 160MHz is replicated to the lower 160MHz. DUP mode is limited to MCS0 using the BPSK modulation scheme, where the code rate is R = 1 / 2, using dual sub-carrier modulation (DCM) and a single NSS. DCM introduces frequency diversity into OFDM to compensate for the unreliability of encoding information on a single subcarrier in a deep fading channel. Specifically, DCM technology maps the same coded information onto two separate, distinct subcarriers separated by frequency using different mapping schemes. In some implementations, the U-SIG field 212 may include an MCS subfield indicating the MCS and a DCM indicator bit indicating whether DCM is applied to subsequent fields. If the DCM indicator bit is zero, the receiver calculates the logarithm likelihood ratio (LLR) of the received bits for each subcarrier based on the indicated MCS. On the other hand, if the DCM indicator bit is equal to 1, the receiver calculates the LLR by performing LLR combining on the upper and lower subcarriers of the RU. In some implementations, when DCM is applied, the ODFM symbols of the payload portion 204 may be encoded by a binary convolution code (BCC) encoder. In some implementations, the coded data may be interleaved, and the interleaved bits may be repeated on both halves of the RU. The interleaved information bits may then be modulated and mapped to constellation symbols, which may be copied or otherwise block-coded. Upon receiving the constellation symbols, they are mapped onto the half of the subcarriers carrying half of the ODFM symbols. Phase-shifted constellation symbols are mapped onto the other half of the subcarrier. Therefore, in addition to replication in the time domain, DCM effectively repeats the same ODFM symbols twice. As a result of the replication of payload portion 206, a 3dB gain improvement can be obtained. Furthermore, as a result of utilizing the DCM coding scheme in MCS0, such as... Figure 4 As shown, a further 5dB gain improvement can be provided. Specifically, Figure 4Simulated graphs show the performance of BPSK MCS0 alone and BPSK MSC0 utilizing DCM on a deep non-line-of-sight (D-NLOS) channel with 242 RUs and one NSS with 2000 1000-byte data packets. The graph shows the packet error rate (PER) on the y-axis as a function of the signal-to-noise ratio (SNR) on the x-axis. It can be observed that for a similar PER, MSC0 utilizing DCM typically exhibits a gain of approximately 5 dB. In summary, the proposed DUP mode can provide up to 8 dB of additional gain for payload portion 204, thereby extending the range and coverage of the LPIPDU.

[0075] However, even if the receiver can combine the repeating U-SIG field 212 in the frequency domain, it cannot guarantee that it will maintain more reliable detection than the payload. For example, in the implementation shown in Figure 3, even if four repeating U-SIG fields 212 can be combined, this will only produce a 6dB gain, which is still lower than the 8dB gain of the payload portion 206. Furthermore, preamble puncturing has been available since the 11ax standard. In transmissions with bandwidths of 80MHz or greater, preamble puncturing allows non-primary 20MHz channels to be zeroed out or not transmitted, hence the term "punctured." Therefore, in the embodiment shown in Figure 3, signals in one of the four repeating fields 206A to 206D, 212A to 212D, and 214A to 214D, or signals in two consecutive 20MHz channels (i.e., 206B, 212B, and 214B) or two discontinuous 20MHz channels (i.e., 206B, 212B, 214B and 206C, 212C and 214C), or signals in two non-consecutive 20MHz channels (i.e., 206B, 212B, 214B and 206D, 212D and 214D), can be punctured. To determine the preamble puncturing pattern, the unpunctured U-SIG field 212 needs to be decoded. In such an embodiment, if one or more U-SIG fields 212A to 212D are punctured, the 6dB gain of the preamble portion 202 cannot be achieved, which further reduces the robustness of the preamble portion 202. In some implementations, the AP can identify single-user (SU) preamble puncturing transmissions and can signal, for example, via the version-independent / relevant portion of the U-SIG field 212 that the resource unit (RU) size is allocated to the same user or STA to indicate SU preamble puncturing transmissions. Since the payload is copied to the other half of the PPDU using one half of the PPDU BW and the MCS of the LPI frame payload is MCS0+DCM, the payload portion is still more reliable than the preamble portion.

[0076] Figure 5 An EHTLPIPPDU 400 for wide BW LPI LR communication, according to an embodiment of this disclosure, is shown. The EHT LPIPPDU 400 is shown as having an 80MHz bandwidth channel. However, it should be understood that the following description can be extended to 160MHz and 320MHz bandwidth channels with necessary modifications.

[0077] In the illustrated embodiment, the EHT LPIPPDU 400 includes a preamble portion 402 and a payload portion 404. The preamble portion 402 includes a conventional preamble 406 and an EHT preamble 410.

[0078] In some implementations, the conventional preamble 406 may be the same as the conventional preamble 206, which is configured for backward compatibility and coexistence with conventional IEEE 802.11 devices.

[0079] EHT preamble 410 includes a first U-SIG field 412, a second or repeated U-SIG (RU-SIG) 414, EHT-STF 416, and EHT-LTF 418.

[0080] In some implementations, the preamble portion, including the conventional preamble 406, the U-SIG field 412, and the RU-SIG field 414, is repeated once every 20 MHz in the frequency domain. Therefore, in the illustrated implementation with an 80 MHz bandwidth channel, fields 406, 412, and 414 are each repeated four times as 406A to 406D, 412A to 412D, and 414A to 414D, respectively. The EHT-STF 416, EHT-LTF 418, and payload portion 404 can occupy the entire 80 MHz channel bandwidth.

[0081] In the illustrated embodiment, the fields U-SIG 412, EHT-STF 416, EHT-LTF 418 and payload portion 404 are the same as those in U-SIG 212, EHT-STF 416, EHT-LTF 418 and payload portion 404, and their descriptions are not repeated here for the sake of brevity.

[0082] In EHT LPIPPDU 400, the EHT-SIG field from EHT LPIPPDU 200 is replaced by RU-SIG 414. This is made possible at least in part by the defined operation fields of the DUP mode LPIPPDU. Specifically, DUP mode is defined for non-punctured preambles, where the MCS is set to MCS0, the NSS is restricted to 1, and transmission is used only for a single STA or single user (SU). Therefore, the EHT-SIG field, which is used for encoding the MCS and NSS in common fields and for MU communication in user-specific fields, may be obsolete because the receiver can identify the value of such a control signal without EHT-SIG once it detects EHT LPIPPDU 400. In some implementations, the presence of RU-SIG 414 can provide a more robust preamble section 402 than the preamble section 402 of the payload section 404. The two time-domain repetitions of the U-SIG field in the first U-SIG field 412 and the second RU-SIG field 414 can provide a 3dB gain in the SNR of preamble detection, especially the U-SIG field. In addition to the four frequency-domain repetitions of the U-SIG field, the two time-domain repetitions of the U-SIG field in the first U-SIG field 412 and the second RU-SIG field 414 provide at least 5dB or greater gain in the SNR of preamble detection, and at least 9dB gain in the SNR of preamble detection. The EHT LPIPPDU 400 provides a more robust preamble portion 402 compared to the 8dB gain of the payload portion 404 in DUP mode obtained from payload replication and the use of DCM.

[0083] In some implementations, repeating the first U-SIG 412 into the second RU-SIG 414 allows for automatic detection of the EHT LPIPPDU 400. In some implementations, the length of the first U-SIG field 412 is two OFDM symbols, and correspondingly, the RU-SIG 414 is an identical copy of the two OFDM symbol lengths of the U-SIG 412. The receiver's processor 110 can perform a correlation check between the U-SIG field 412 and the time-domain delayed RU-SIG 414 based on the delay without decoding the U-SIG field. A high correlation output from the correlation function can indicate to the receiver the presence of two U-SIG fields, indicating the EHT LPIPPDU frame 400. The receiver may then be able to combine the frequency-domain repeated U-SIG fields and also combine U-SIG 412 and RU-SIG 414 in the time domain for increased robustness in detection with improved SNR gain.

[0084] Figure 6Another embodiment of the EHTLPIPPDU 500 that can be used for wide BW LPI LR communication according to the embodiments of this disclosure is shown. It should be noted that, for clarity and brevity, the EHT-STF, EHT-LTF, and payload portions are shown as a single block, and they are not intended to be a single field.

[0085] Except that, instead of replacing EHT-SIG with a single RU-SIG after field U-SIG 512, EHT LPIPPDU 500 includes multiple (i.e., two or more) U-SIG 512 in RU-SIG 514(1)...514(n), EHT LPIPPDU 500 is otherwise identical to EHT LPIPPDU 400, where n is a positive integer. In some implementations, U-SIG field 512 is identical to U-SIG 212, 412 described above. The increased temporal repetition of the U-SIG signal can provide additional gain in the SNR of the preamble portion detection, expressed in dB, which can be calculated as:

[0086] ΔSNR = 10log(n)

[0087] Therefore, the overall improvement in SNR for preamble detection of EHT LPIPPDU 500 can be 5dB+ΔSNR. For example, for two RU-SIGs, the gain improvement can be approximately 10dB of 5dB+~5dB. EHT LPIPPDU 500 can be automatically detected by performing a correlation check similar to the correlation check of EHT LPIPPDU 400 described above between U-SIG 512 and the first RU-SIG 514 (1).

[0088] Figure 7Another embodiment of an EHT LPIPPDU 600 for use in wide BW LPI LR communication, according to an implementation of this disclosure, is shown. The EHT LPIPPDU 600 is otherwise identical to the EHT LPIPPDU 400, except that it includes a first U-SIG 612 and a subsequent second U-SIG2 field 614. In some embodiments, the U-SIG field 612 is identical to the aforementioned U-SIG fields 212 and 412. The second U-SIG2 field 614 may carry the same content as U-SIG 612. In some embodiments, a DCM scheme is applied to U-SIG2, for example, as described in PCT / CN2020 / 106313, the entire content of which is incorporated therein. In some embodiments, the DCM scheme may be the same as the DCM scheme applied to MCS 0 / 1 / 3 / 4 as stated in the 11ax standard, in which phase shifting is applied to each subcarrier. By applying DCM to the non-limiting example MCS0 of the payload portion in DUP mode, DCM can be applied in conjunction with any suitable MCS. As can be understood, with the application of DCM to U-SIG2 614, it can provide additional SNR improvement in U-SIG detection, thus making preamble detection more robust. Since the content of U-SIG2 614 is identical to that of U-SIG 612, EHT LPI PPDU 600 can be automatically detected by performing a correlation check between U-SIG 612 and U-SIG2 614 similar to the correlation check for EHT LPI PPDU 400 described above.

[0089] In some implementations, U-SIG2 614 may employ a different BCC puncturing pattern than U-SIG 612. Specifically, in implementations where EHT LPIPPDU frames are defined using an MCS with a code rate higher than MCS0 and R=1 / 2, BCC puncturing patterns can be defined for both U-SIG 612 and U-SIG2. In these implementations, the BCC puncturing pattern applied to U-SIG2 may differ in the frequency domain from the puncturing pattern of U-SIG 612, for example, as described in PCT / CN2020 / 106313, all of which are incorporated herein by reference. The different BCC puncturing patterns between U-SIG 612 and U-SIG2 614 can provide a diversity gain of 1 dB to approximately 2 dB, which can make preamble detection of the EHT LPIPPDU 600 more robust.

[0090] In some implementations, a bit-by-bit interleaver scheme can be applied to U-SIG2 614. In some implementations, an interleaver scheme defined in IEEE 802.11 can be reused to apply the interleaver scheme, in which interleaver parameters such as Ncol, Nrow, and Nrot can be reused according to the parameters based on IEEE 802.11 NSD 48 described in PCT / CN2020 / 106313, all of which are incorporated herein by reference. Although implementations have been described with respect to the interleaver scheme defined in IEEE 802.11, it should be understood that any other suitable interleaver scheme may be employed. A bit-by-bit interleaver scheme can provide additional diversity gain for preamble detection of the EHT LPIPPDU 600.

[0091] It should be understood that at least one of the above-mentioned DCM applications, different BCC punching modes, and bit-by-bit interleaver schemes can be applied to the EHT LPIPPDU 600.

[0092] Figure 8 Another embodiment of the EHT LPI PDU 700 for wide BW LPI LR communication, according to an implementation of this disclosure, is shown. As previously described, the DUP mode is defined for a non-punctured preamble, where the MCS is set to MCS0, the NSS is limited to 1, and transmission is used only for a single STA or single user (SU). Therefore, the EHT-SIG field and the MU communication field used for encoding the MCS and NSS can be omitted. Thus, in the EHT LPI PDU 700, the U-SIG field 712 is immediately followed by the ETH-STF, and the EHT-SIG field is omitted. Figure 8 In the embodiment shown, U-SIG712 may include a subfield indicating the type of LPI frame.

[0093] Although methods and processes may be described in a particular order in this disclosure, one or more steps of the methods and processes may be omitted or changed as appropriate. One or more steps may be performed in an order different from the order in which they are described, as appropriate.

[0094] While this disclosure can be described, at least in part, those skilled in the art will understand that, in relation to the methods, this disclosure also relates to various components for performing at least some aspects and features of the described methods, whether by hardware components, software, or any combination of both. Therefore, the technical solutions of this disclosure can be embodied in the form of a software product. Suitable software products can be stored in pre-recorded storage devices or other similar non-volatile or non-transitory computer-readable media, such as DVDs, CD-ROMs, USB flash drives, removable hard drives, or other storage media. The software product includes examples of instructions tangibly stored thereon that enable a processing device (e.g., a personal computer, server, or network device) to perform the methods disclosed herein.

[0095] This disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The exemplary embodiments described are to be considered in all respects as illustrative rather than restrictive. Features selected from one or more of the above embodiments may be combined to create alternative embodiments not explicitly described, and features suitable for such combinations should be understood within the scope of this disclosure.

[0096] All values ​​and sub-ranges within the scope of the disclosure are also disclosed. Furthermore, while the systems, devices, and processes disclosed and illustrated herein may include a specific number of elements / components, the systems, devices, and assemblies may be modified to include more or fewer such elements / components. For example, although any disclosed element / component may be referred to as singular, the embodiments disclosed herein may be modified to include multiple such elements / components. The subject matter described herein is intended to cover and encompass all appropriate technical changes.

[0097] All published documents and standards identified in this disclosure are incorporated herein by reference.

Claims

1. A method for encoding physical layer (PHY) protocol data units (PPDUs) for low-power indoor (LPI) wireless communication, the method comprising: The preamble portion of the PPDU is encoded, wherein the encoding further includes: The first general signal field (U-SIG) is encoded, wherein the first U-SIG includes one or more information bits relating to the payload portion of the PPDU; At least a second U-SIG is encoded, the second U-SIG comprising one or more identical information bits relating to the payload portion of the PPDU; The preamble section does not contain an Extremely High Throughput (EHT) signal field (SIG).

2. The method according to claim 1, wherein, The second U-SIG is encoded after the first U-SIG.

3. The method according to claim 1, further comprising: In addition to the first U-SIG and the second U-SIG, a plurality of U-SIGs are encoded, wherein each of the plurality of U-SIGs includes the same one or more information bits relating to the payload portion of the PPDU.

4. The method according to any one of claims 1 to 3, further comprising: Dual subcarrier modulation (DCM) is applied to the second U-SIG.

5. The method according to any one of claims 1 to 3, further comprising: The bit-by-bit interleaver scheme is applied to the second U-SIG.

6. The method according to any one of claims 1 to 3, wherein, The method further includes encoding the first U-SIG and the second U-SIG using a modulation and coding scheme (MCS) with a code rate greater than 0.

5. The first U-SIG is punctured using a first binary convolutional code (BCC) pattern; and The second U-SIG is subjected to a second BCC punching pattern, wherein the second BCC punching pattern is different from the first BCC punching pattern.

7. The method according to any one of claims 1 to 3, wherein, The LPI wireless communication is defined for extended range operation mode.

8. The method according to claim 7, wherein, The extended range operation mode is defined for the MCS scheme of MCS0, which uses a single spatial stream in a non-puncturing channel with one of the bandwidths of 80MHz, 160MHz, and 320MHz for a single site (STA).

9. An apparatus for an access point (AP), the apparatus comprising a non-transitory memory storage unit and a processing unit operatively coupled to the non-transitory memory storage unit, the processing unit being configured to: The preamble portion of the physical layer (PHY) protocol data unit (PPDU) for low-power indoor (LPI) wireless communication is encoded, wherein... The preamble portion of the PPDU includes: A first general signal field (U-SIG) is provided, wherein the first U-SIG includes one or more information bits relating to the payload portion of the PPDU; At least a second U-SIG, the second U-SIG comprising one or more identical information bits relating to the payload portion of the PPDU; and Transmit the encoded PPDU; The preamble section does not contain an Extremely High Throughput (EHT) signal field (SIG).

10. The apparatus according to claim 9, wherein, In addition to the first U-SIG and the second U-SIG, the preamble portion also includes a plurality of U-SIGs, wherein each of the plurality of U-SIGs includes the same one or more information bits relating to the payload portion of the PPDU.

11. The apparatus according to claim 9 or 10, wherein, The processing unit applies the DCM scheme to the second U-SIG.

12. The apparatus according to any one of claims 9 to 10, wherein, The processing unit applies the bit-by-bit interleaver scheme to the second U-SIG.

13. The apparatus according to any one of claims 9 to 10, wherein, The first U-SIG and the second U-SIG are encoded using a modulation and coding scheme (MCS) with a code rate greater than 0.5, wherein, The processing unit applies the first binary convolutional code (BCC) puncturing pattern to the first U-SIG; and The processing unit applies a second BCC punching mode to the second U-SIG, wherein the second BCC punching mode is different from the first BCC punching mode.

14. An apparatus for a station (STA), the apparatus comprising a non-transitory memory storage unit and a processing unit operatively coupled to the non-transitory memory storage unit, the processing unit being configured to: The preamble portion of the Physical Layer (PHY) Protocol Data Unit (PPDU) for receiving low-power indoor (LPI) wireless communication, wherein, The tests also include: Detect the first general signal field (U-SIG) in the preamble portion of the PPDU, wherein the first U-SIG includes one or more information bits about the payload portion of the PPDU; Detect at least a second U-SIG, the second U-SIG comprising one or more identical information bits relating to the payload portion of the PPDU; Combining the first U-SIG and the second U-SIG; and Based on the combined first U-SIG and second U-SIG, the preamble portion of the PPDU is decoded; The preamble section does not contain an Extremely High Throughput (EHT) signal field (SIG).

15. The apparatus according to claim 14, wherein, Before combining the first U-SIG and the second U-SIG, the processing unit is configured to: Perform a correlation check between the first U-SIG and the second U-SIG; and When there is a positive correlation, it is automatically determined that the PPDU is configured for low-power indoor (LPI) wireless communication.

16. The apparatus of claim 15, wherein the automatic determination of the PPDU further comprises automatically determining the MCS scheme of MCS0, the MCS scheme of MCS0 using a single spatial stream in a non-puncturing channel having one of a bandwidth of 80 MHz, 160 MHz, and 320 MHz for a single site (STA).

17. The apparatus according to any one of claims 14 to 16, wherein, In addition to the first U-SIG and the second U-SIG, the preamble portion also includes multiple U-SIGs, and the processing is further configured to: The multiple U-SIGs are combined with the first U-SIG and the second U-SIG to improve the robustness of the preamble portion detection.

18. The apparatus according to any one of claims 14 to 16, wherein, The processing unit is also configured to decode the second U-SIG that has applied the DCM scheme.

19. The apparatus according to any one of claims 14 to 16, wherein, The first U-SIG and the second U-SIG in the preamble portion of the received PPDU are encoded using a modulation and coding scheme (MCS) with a code rate greater than 0.5, and the processing unit is further configured to: Detect the first U-SIG with the first binary convolutional code (BCC) puncturing pattern; as well as A second U-SIG with a second BCC punch pattern is detected, wherein the second BCC punch pattern is different from the first BCC punch pattern.

20. A method for encoding physical layer (PHY) protocol data units (PPDUs) for low-power indoor (LPI) wireless communication, the method comprising: The preamble portion of the PPDU is encoded, wherein the encoding further includes: The first general signal field (U-SIG) is encoded, which includes one or more information bits about the payload portion of the PPDU, while there is no extremely high throughput (EHT) signal field (SIG) in the preamble portion.

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