Modification of LDPC rate matching

Abstract

One method for improving low-density parity-check (LDPC) rate matching includes adding LDPCExtra symbols to improve decoding performance and optimizing the pre-forward error correction (FEC) padding factor to reduce the number of padding bits.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 548,110, filed November 10, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure generally relates to a wireless communication system. Background Technology

[0004] IEEE 802.11 is a set of standards for wireless LANs, commonly known as Wi-Fi. Several revisions to the IEEE 802.11 standard have introduced Orthogonal Frequency Division Multiplexing (OFDM) as a modulation scheme. OFDM is a multi-carrier modulation technique used in Wi-Fi to synchronously transmit data on multiple subcarriers. Detailed Implementation

[0005] The implementation described in this disclosure generally relates to a system and technique for rate matching in wireless communication systems that implement forward error correction (FEC) codes, such as low-density parity-check (LPDC) codes.

[0006] The following section provides an overview of IEEE 802.11-based systems that can apply the implementations of this disclosure.

[0007] Overview of IEEE 802.11-based systems

[0008] The implementations described herein can be applied to various wireless communication systems. For example, the implementations disclosed herein can be applied to wireless local area network (WLAN) systems. In some implementations, the WLAN implementation conforms to one or more IEEE 802.11 standards (such as IEEE 802.11a / g / n / ac standards, IEEE 802.11ax standards, and / or IEEE 802.11be standards, etc.). Generally, the implementations disclosed herein can be applied to other types of wireless communication systems and are not limited to a specific technical standard.

[0009] Figure 1 This is a diagram illustrating an example of a wireless network environment 100. The wireless network environment 100 may include a first device 110 and a second device 120.

[0010] Devices 110 and 120 can implement various types of devices in the wireless network 100. For example, one or more of devices 110 and 120 can implement a mobile device (also called a mobile terminal), a station (STA), a wireless transceiver unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit, or a user, etc. Additionally, one or more of devices 110 and 120 can implement other types of devices, such as a network, an access point (AP), a base station (BS), a node-B, a repeater, a router, or a relay, etc. Devices 110 and 120 can also be referred to by other terms, such as receiving equipment, transmitting equipment, receiving STA, transmitting STA, transmitting AP, receiving AP, receiving device, or transmitting device, etc.

[0011] In some implementations, devices 110 and 120 can be used as either an access point (AP) or a non-AP. For example, devices 110 and 120 can be used as both an AP and / or a non-AP.

[0012] In some scenarios, devices 110 and 120 can also support various communication standards other than the IEEE 802.11 standard. For example, they can support communication standards based on the 3GPP standard family (e.g., LTE, LTE-A, 5G NR standards). Furthermore, devices 110 and 120 can be implemented as various types of devices, such as mobile phones, vehicles, or personal computers. In addition, devices 110 and 120 can support communication for various communication services (such as voice calls, video calls, data communication, and autonomous driving).

[0013] Devices 110 and 120 can be configured to communicate with each other wirelessly or wiredly via one or more communication networks. The communication network can be any combination of, but is not limited to, different types of suitable communication networks, such as broadcast networks, wired networks, public networks (e.g., the Internet), private networks, wireless networks, cellular networks, or any other suitable private and / or public networks. Furthermore, the communication network can have any suitable communication range associated with it and can include, for example, global networks (e.g., the Internet), metropolitan area networks (MANs), wide area networks (WANs), local area networks (LANs), or personal area networks (PANs). Additionally, the communication network can include any type of medium capable of carrying network traffic, including but not limited to coaxial cables, twisted-pair cables, optical fibers, hybrid fiber-coaxial (HFC) media, microwave terrestrial transceivers, radio frequency communication media, white space communication media, ultra-high frequency communication media, satellite communication media, or any combination thereof.

[0014] Devices 110 and 120 may include one or more communication antennas. The one or more communication antennas may be any suitable type of antenna corresponding to the communication protocol used by devices 110 and 120. Some non-limiting examples of suitable communication antennas include Wi-Fi antennas, IEEE 802.11 family of standard-compliant antennas, directional antennas, non-directional antennas, dipole antennas, folded dipole antennas, patch antennas, multiple-input multiple-output (MIMO) antennas, omnidirectional antennas, or quasi-omnidirectional antennas, etc. One or more communication antennas may be communicatively coupled to radio components to transmit signals such as communication signals to and / or receive signals such as communication signals from devices 110 and 120.

[0015] Devices 110 and 120 can be configured to perform directional transmission and / or directional reception in conjunction with wireless communication in a wireless network. Devices 110 and 120 can be configured to use a set of multi-antenna arrays (e.g., DMG antenna arrays, etc.) for such directional transmission and / or reception. Each array in the multi-antenna array can be used for transmission and / or reception in a specific corresponding direction or directional range. Devices 110 and 120 can be configured to perform any given directional transmission toward one or more defined transmit sectors. Devices 110 and 120 can be configured to perform any given directional reception from one or more defined receive sectors.

[0016] In some implementations, RF beamforming and / or digital beamforming can be used to perform MIMO beamforming in a wireless network. When performing a given MIMO transmission, devices 110 and 120 can be configured to use all or a subset of one or more of their communication antennas for MIMO beamforming.

[0017] Devices 110 and 120 may include a media access control (MAC) conforming to the IEEE 802.11 standard and a physical layer interface for radio media.

[0018] The first device 110 may include a processor 111, a memory 112, and a transceiver 113. The processor 111, memory 112, and transceiver 113 may be implemented as separate chips, or at least two blocks / functions may be implemented by a single chip.

[0019] The transceiver 113 of the first device 110 can perform signal transmission / reception operations. For example, it can transmit / receive IEEE 802.11 data packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0020] Transceiver 113 may refer to any suitable radio and / or transceiver for transmitting and / or receiving radio frequency (RF) signals in a bandwidth and / or channel corresponding to the communication protocol used in communication between the first device 110 and the second device 120. The radio component may include hardware and / or software for modulating and / or demodulating communication signals according to a pre-established transmission protocol. The radio component may also have hardware and / or software instructions for communicating via one or more Wi-Fi and / or Wi-Fi Direct protocols standardized by the IEEE 802.11 standard. For example, the radio component cooperating with a communication antenna may be configured to communicate in one or more frequency bands (such as 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). The radio component may include any known receiver and baseband suitable for communication via a communication protocol. The radio component may also include other components such as a low-noise amplifier (LNA), an additional signal amplifier, an analog-to-digital (A / D) converter, one or more buffers, and one or more digital basebands.

[0021] In some implementations, the first device 110 can be implemented as an access point (AP) operating in a WLAN system. For example, the AP's processor 111 can receive signals via transceiver 113, process receive (RX) signals, generate transmit (TX) signals, and provide control over signal transmission. The AP's memory 112 can store signals received via transceiver 113 (e.g., RX signals) and signals to be transmitted via transceiver 113 (e.g., TX signals).

[0022] In some implementations, the second device 120 can be a non-AP device, such as a station (STA). For example, the non-AP transceiver 123 can perform signal transmission / reception operations. For example, it can transmit / receive IEEE 802.11 data packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be data packets, etc.).

[0023] In some implementations, the processor 121 of the non-AP device can receive signals via transceiver 123, process RX signals, generate TX signals, and provide control over signal transmission. The memory 122 of the non-AP device can store signals received via transceiver 123 (e.g., RX signals) and signals to be transmitted via transceiver 123 (e.g., TX signals).

[0024] In some implementations, the operation of device 110 (120) can be controlled by processing chip 114 (124) of device 110 (120). For example, software code 115 (125) related to the operation of device 110 (120) can be stored in memory 112 (122) of device 110 (120), and the software code can be executed by processor 111 (121) to control the operation of device 110 (120).

[0025] In a scenario where network 100 implements the IEEE 802.11 standard, devices 110 and 120 can communicate via Physical Layer (PHY) Protocol Data Units (PPDUs). Each PPDU's frame format includes a preamble appended to the data. The preamble includes various fields and subfields that can be used for various purposes (e.g., automatic gain control, timing synchronization, etc.) and provides information to the receiver to correctly receive the data in the PPDU. Examples of fields that can be implemented in a PPDU (including preamble fields and data fields) are shown below:

[0026]

[0027] The fields listed above are merely examples of fields that may be included in a PPDU. Typically, a PPDU may include only some of these fields, and may also include other fields (and subfields). Furthermore, the specific names of the fields shown above are merely examples, and the specific names of the fields are not limited to these. For example, in some implementations, other names (such as Ultra High Throughput (UHT)-LTF, etc.) may be used instead to refer to EHT-LTF.

[0028] Examples of operations used to generate TX / RX signals or to pre-process and compute data may include: determining / obtaining / configuring / computing / decoding / encoding bit information of fields included in a PPDU; determining / configuring / obtaining time or frequency resources (e.g., subcarrier resources) for fields included in a PPDU; determining / configuring / obtaining specific sequences (e.g., pilot sequences, STF / LTF sequences, additional sequences applied to SIG) for fields included in a PPDU; power control operations and / or power saving operations applied to the device; and determining / obtaining / configuring / decoding / encoding ACK signals.

[0029] In some implementations, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various devices to determine / obtain / configure / calculate / decode / decode TX / RX signals can be stored in memories 112 and 122.

[0030] In some implementations, processing chips 114 and 124 may include processors 111 and 121 and memories 112 and 122. In some implementations, processing chips 114 and 124 may perform operations for mobile terminals, wireless devices, wireless transmit / receive units (WTRUs), user equipment (UEs), mobile stations (MSs), mobile subscriber units, users, subscriber stations (STAs), networks, base stations, nodes-Bs, access points (APs), repeaters, routers, relays, receiving units, transmitting units, receiving STAs, transmitting STAs, receiving devices, transmitting devices, receiving equipment, and / or transmitting equipment. For example, the technical features of devices 110 and 120 discussed herein may be performed by processing chips 114 and 124.

[0031] In some implementations, software codes 115 and 125 may be included in memories 112 and 122. Software codes 115 and 126 may include instructions for controlling the operation of processors 111 and 121. Software codes 115 and 125 may be included in various programming languages.

[0032] Processors 111 and 121 or processing chips 114 and 124 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The processor may be an application processor (AP). For example, processors 111 and 121 or processing chips 114 and 124 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem.

[0033] An uplink is a directional link used for communication from a non-AP (e.g., STA) to an AP. Uplink PPDUs / data packets / signals, etc., can be transmitted via the uplink. Similarly, a downlink is a directional link used for communication from an AP to a non-AP (e.g., STA). Downlink PPDUs / data packets / signals, etc., can be transmitted via the downlink.

[0034] Figure 2A and Figure 2B This is a diagram illustrating an example of a PPDU based on the IEEE 802.11 standard. Figure 2A and Figure 2B The specific PPDU formats and fields shown are merely examples, and it should be understood that PPDUs can be implemented without one or more of the fields shown in these figures, and / or PPDUs can implement other fields not shown in these figures.

[0035] Figure 2AThe example illustrates a PPDU, which includes various fields such as the conventional short training field (L-STF), conventional long training field (L-LTF), conventional signal field (L-SIG), repeated conventional signal field (RL-SIG), universal signal field (U-SIG), EHT signal field (EHT-SIG), EHT short training field (EHT-STF), and EHT long training field (EHT-LTF). These fields form the preamble of the PPDU. Additionally, in Figure 2A In the example, the PPDU includes the data field that immediately follows the EHT-LTF.

[0036] Figure 2A The PPDU depicted can be sent to a single user or multiple users. The associated EHT-SIG field, along with U-SIG, provides the device with the necessary RU / MRU allocation and other information to understand the data packet. In some implementations, when the PPDU is sent to multiple users, the transmission can be OFDMA or MU-MIMO. In some implementations, RUs with 242 or more tones included in an OFDMA transmission can employ MU-MIMO technology to synchronously transmit that RU to up to eight users.

[0037] Figure 2B The example illustrates a PPDU that includes various fields such as L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-STF, and EHT-LTF. These fields form the preamble of the PPDU. Additionally, in Figure 2B In this context, the PPDU includes the data field that immediately follows the EHT-LTF.

[0038] Figure 2B The PPDU frame format in Figure 2A The PPDU frame format is similar, but the difference is that... Figure 2B The format does not include the EHT-SIG field. Furthermore, with... Figure 2A Compared to the EHT-STF field in the previous implementation, this EHT-STF field can be extended to twice its length to improve uplink transmission performance and reliability. In some implementations, Figure 2B A PPDU can be transmitted by a device in response to receiving a control frame (e.g., a "trigger frame") from an AP, wherein the control frame allocates resources and requests a response from one or more devices. Therefore, the device can use... Figure 2B The PPDU described in the diagram is used to respond to the trigger sent by the AP.

[0039] In some implementations, the PPDU may include a field indicating whether additional resources are available for transmitting FEC-decoded bits. For example, the PPDU preamble may include a field indicating whether additional OFDM symbols or segments are available for transmitting LDPC bits. In some implementations, this field may be called the "LDPCExtra" field (or other suitable name) and may be implemented as part of signal fields in the PPDU, such as the EHT-SIG field or U-SIG field. As an example, if additional OFDM symbol segments for LDPC are available, the value of "LDPCExtra" may be "1". Otherwise, if no additional OFDM symbol segments for LDPC are available, the value of "LDPCExtra" may be set to "0".

[0040] The next section presents an overview of rate matching (e.g., as implemented in IEEE 802.11-based systems).

[0041] Overview of Rate Matching

[0042] In a transmitter implementing FEC, the number of information bits Encoded into a larger number of FEC code points (Right now, This provides redundancy and protection against errors. Following FEC encoding, Each coded bit is modulated using an appropriate modulation scheme to generate a signal that is transmitted through the communication channel. A modulation symbol (e.g., an OFDM symbol).

[0043] Rate matching is a technique that adjusts coding parameters to make the FEC (Failure Estimation) equal to the number of coded bits. and The total number of bits that can be accommodated in each OFDM symbol matches. Each OFDM symbol can transmit the number of FEC-coded bits. (Number of code points per symbol), this number It depends on the specific modulation and decoding scheme (MCS) and the number of spatial streams used for transmission. Therefore, for a given number of OFDM symbols... , The total number of FEC-coded bits that a symbol can hold is The bit, which is represented in this article as Bit( ).

[0044] In some scenarios, The actual number of coded bits to be transmitted can be compared with the actual FEC to be transmitted. The difference lies in the encoding parameters. In this scenario, the transmitter can adjust one or more encoding parameters to match the number of FEC-coded bits to the total number of bits that can be accommodated in the OFDM symbol. For example, the transmitter can achieve rate matching using techniques such as shortening, puncturing, and / or repetition. Shortening is a technique that reduces the length of the encoded codeword by shortening the input of the FEC encoder (e.g., by selecting only a subset of the information bits to be encoded), padding the shortened information bits with extra bits before encoding to ensure the codeword is padded, and then removing the extra coded bits at the output of the FEC encoder before transmission. Punching is another technique that reduces the length of the encoded codeword by removing (puncturing) multiple coded bits (i.e., puncturing some bits at the output of the FEC encoder). In contrast, repetition is a technique that increases the length of the encoded codeword by repeating coded bits (i.e., repeating some bits at the output of the FEC encoder).

[0045] Examples of values ​​for these coding parameters for various modulation schemes are shown in Tables 36-76 below. These are merely examples, and the implementations described herein are not limited to these specific values.

[0046]

[0047] According to the implementation of this disclosure, the next part presents various modifications to the LDPC code for rate matching in scenarios where FEC is used (e.g., for IEEE 802.11-based systems).

[0048] Modification of LDPC rate matching

[0049] LDPC rate matching algorithms are typically constrained by the following problems:

[0050] (1) Performance is reduced compared to previous generations of Wi-Fi (802.11n);

[0051] (2) Due to excessive pre-FEC filling, power consumption increases and potential performance degrades.

[0052] To address these issues, the implementation of this disclosure enables two modifications to improve the performance of LDPC rate matching (e.g., for IEEE 802.11be systems):

[0053] (1) Force the addition of the “LDPCExtra” symbol to improve performance;

[0054] (2) Optimize the fill factor before FEC to reduce the number of fill bits.

[0055] Modification 1: Force LDPCExtra symbol segment.

[0056] If puncturing is used to reduce the number of coded bits in an LDPC codeword, it is possible to puncture too many coded bits, leading to excessive performance degradation. To avoid this performance degradation, a technique can be used that adds extra resources to transmit LDPC coded bits if (according to a certain criterion) the number of punctured LDPC coded bits is "excessive." An example of such a criterion ("Criterion A") is shown below to determine the degree of "excessive" puncturing.

[0057] Criterion A:

[0058]

[0059] in:

[0060] N_punc,u is the number of punched holes for user u;

[0061] N_shrt,u is the number of shortened bits for user u;

[0062] R_u is the code rate for user u;

[0063] N_cw,u is the total number of LDPC codewords for user u.

[0064] It should be understood that criterion A is merely an example of a criterion for determining whether to add an additional LDPC symbol segment, and other criteria can typically be used.

[0065] If criterion A is triggered (equal to TRUE), the PPDU size will be expanded to accommodate more LDPC codewords. This can result in reduced or no puncturing, or even repetition if the expanded PPDU size provides ample space for the LDPC codewords. In some implementations, the PPDU can be expanded by adding additional OFDM symbol segments for transmitting the LDPC codewords. For example, if initial calculations determine that one OFDM symbol is needed to accommodate the LDPC codewords to be transmitted, but criterion A is subsequently triggered, the total number of OFDM symbols can be increased to two, making the "container" (PPDU) larger for the same number of LDPC codewords, thereby reducing the number of LDPC codewords that need to be punctured.

[0066] If additional LDPC symbol segments are added, in some implementations, the transmitter can indicate this to the receiver by setting a specific field in the PPDU. For example, in an IEEE 802.11-based system, the transmitter can indicate the presence of additional OFDM symbol segments by setting the “LDPCExtra” field in the PPDU. The receiver then receives this indication and is able to correctly decode the received LDPC codewords.

[0067] However, adding additional OFDM symbol segments only when criterion A is met may be too restrictive. Instead, performance can be further improved by providing greater flexibility to add additional OFDM symbol segments even when criterion A is not met.

[0068] For example, as a modification to the above technique, instead of adding extra LDPC symbols only when criterion A is triggered, extra LDPC symbol segments can be added all the time; that is, the LDPCExtra field can always be set to 1. The advantage is that the extra OFDM symbol segments will reduce the code rate, which will in turn improve performance. This benefit may outweigh the disadvantage of the additional latency imposed by the extra OFDM symbol segments, resulting in an overall performance gain. Figure 3A and Figure 3B An example of the performance gains achievable through this modified LDPC rate matching technique is shown.

[0069] The modified LDPC rate matching technique can be described as follows:

[0070] When de-ratemaching is performed on the receiver side, the receiver should always comply with the LDPCExtra signaling indicated in the preamble, even if the receiver derives a different LDPCExtra value (by calculation based on other parameters in the preamble) than the value of LDPCExtra indicated in the received preamble.

[0071] Therefore, the receiver always adheres to the LDPCExtra signaling in the received preamble (which is sent by the transmitter) and does not rely on its own computation (e.g., its own computation of criterion A). This can also be expressed as:

[0072] The receiver should always use the following formula (Guideline B) to update the N_avbits,u and N_punc,u calculations in the rate matching solution, since LDPCExtra is always set to 1 in the preamble, where N_avbits,u represents the total number of available bits in the PPDU (including any LDPCExtra symbols).

[0073] Criterion B:

[0074]

[0075] Therefore, in criterion B, equations 36-56 describe updating the value of N_avbits,u based on the value of a_init.

[0076] Next, another modification to LDPC rate matching will be described.

[0077] Modification 2: FEC pre-padding factor used to reduce the number of padding bits.

[0078] In some scenarios, the pre-filling for FEC is determined by the following process:

[0079] First, divide an RU into 4 blocks. The number of tones in each block is N_SD,short. For example, RU26 has a total of 24 data tones, such that N_SD_Short = 24 / 4 = 6.

[0080] Next, find the minimum boundary that can only accommodate this number of information bits. The boundary is denoted as the FEC pre-padding factor a_init. This is the initial number of symbol segments required to accommodate a given number of information bits in the last OFDM symbol.

[0081] Based on the above process, the last OFDM symbol of the PPDU can be divided into four symbol segments using four FEC pre-padding boundaries. FEC pre-padding can include padding bits up to one of these four boundaries.

[0082] This process can be used in IEEE 802.11be systems. An example of this process is available in... Figure 4A As shown in the image.

[0083] exist Figure 4A and Figure 4B In the example, the green areas represent information bits, and the red areas represent padding bits. As shown, the number of information bits is insufficient to fill the first boundary (which corresponds to a_init=1). Therefore, padding bits are added to fill the initial boundary a_init=1.

[0084] As shown in the figure, the above process may potentially require a large number of padding bits to fill up to the boundary, resulting in a large number of LDPC codewords to be decoded per symbol at the receiver, and requiring greater power consumption to decode the same number of information bits.

[0085] A more fine-grained FEC prefilling was achieved based on a modified version of LDPC rate matching. Figure 4B An example of this modified LDPC rate matching is shown. For example... Figure 4B As shown in the example, for with Figure 4AWith the same number of information bits, fewer padding bits (marked in red) are added to fill up to the initial boundary a_init (which is again equal to 1 in this example). Fewer padding bits result in fewer LDPC codewords to decode per symbol at the receiver, which makes it possible to decode the same number of information bits with less power.

[0086] In some implementations, finer-grained FEC prepush boundaries can be achieved by reducing the value of N_SD,short as defined in Table 1 below. In Table 1, the last column (marked in red) is an example of a modified definition of N_SD,short that introduces 16 FEC prepush boundaries instead of 4.

[0087] Table 1:

[0088]

[0089] The following describes a further modification to LDPC rate matching, which uses a finer granularity for pre-FEC padding (as described in the previous modification), but a coarser granularity for post-FEC LDPCExtra symbols.

[0090] Modification 3: For the different granularities of LDPCExtra before FEC and after FEC.

[0091] Considering the above discussion Figure 4A and Figure 4B The example of FEC prepadding includes a scenario where FEC is added to the LDPCExtra symbol field after LDPC encoding. In such a scenario, FEC prepadding bits are added to the information bits before LDPC encoding, and one or more LDPCExtra symbol fields are added to the encoded bits after LDPC encoding.

[0092] from Figure 4A The example begins with coarser-grained FEC pre-padding, and the additional coarser-grained FEC post-LDPCExtra symbol segment causes the boundary to move to a=a_init+1=2. Figure 5A This shows the coarser-grained boundary obtained with the FEC-fed LDPCExtra symbol segment.

[0093] Similarly, in Figure 4B In the finer-grained example, the additional finer-grained FEC followed by the LDPCExtra symbol segment causes the boundary to shift. Figure 4B In this context, a = a_init + 1 = 2. However, due to... Figure 4B The granularity is smaller, therefore the boundary of a=2 obtained is... Figure 5A Much smaller in comparison. In other words, compared to Figure 4ACompared to coarser-grained examples, in Figure 4B Adding FEC to the LDPCExtra symbol segment will result in a smaller PPDU size. For the same number of information bits, the smaller PPDU size (fewer code bits) leads to a higher code rate, which results in worse error performance.

[0094] To address this issue, based on further modifications to LDPC rate matching, whenever... Figure 4B When adding a finer-grained FEC-after LDPCExtra symbol segment to a finer-grained FEC-before-fill scene, an additional finer-grained FEC-after symbol segment is added to be equal in length to... Figure 4A The original (coarser-grained) LDPCExtra symbol segment. The following... Figure 5B This example shows the resulting boundary of the LDPCExtra symbol segment after adding FEC. As this example shows, when LDPCExtra is called, instead of adding a single, finer-grained symbol segment... Figure 5B (One rectangular block in the middle), LDPCExtra adds multiple finer-grained FEC-post symbol segments, the total length of which is equal to the length of a single coarser-grained symbol segment (in the middle). Figure 5B In the example, four finer-grained symbol segments are added, these four finer-grained symbol segments being equal in length to Figure 5A (A single, coarser-grained segment of symbols).

[0095] Figure 5B Fine-grained FEC prefilling, coarser-grained FEC post-LDPC Extra.

[0096] Therefore, the LDPCExtra feature can achieve similar additional coding time as coarser-grained scenarios (e.g., repeating more bits). This achieves a much smaller code rate compared to simply adding a single, finer-grained symbol segment (much fewer FEC prepuppet bits, but a similar number of additional FEC-postpuppet bits added by LDPCExtra). Furthermore, compared to... Figure 5A Compared to the coarser-grained example, the overall PPDU size (and thus the resulting latency) is maintained or can actually be reduced, mainly because the initial boundary size is smaller when a_init=1.

[0097] As an example of implementing this process for an IEEE 802.11be system, if the LDPCExtra symbol segment is set, N_avbits,u will be updated via equations 36-56 (repeated below), where N_CBPS,short,u is derived from N_SD,short. Because the modified LDPC rate matching process described above (using coarser-grained FEC after LDPCExtra and finer-grained FEC before padding) reduces N_SD,short, the PPDU size may not increase as expected.

[0098]

[0099] This process can be represented as follows: When LDPCExtra is triggered, the second column of Table 1 (i.e., the original value of N_SD,short) should still be used to calculate N_CBPS,short,u in formulas 36-56. This process can improve performance because: for the same number of information bits, with far fewer FEC prepupaging bits, LDPCExtra adds the same amount of additional PPDU size as in a coarser-grained scenario (in... Figure 5B The redundancy added by increasing a_init from 1 to 5 in the modified scheme is the same as that in... Figure 5A The amount of redundancy added by increasing a_init from 1 to 2 is the same as that added in the original coarser-grained scheme.

[0100] All of the above-mentioned modified LDPC rate matching schemes can improve LDPC performance and reduce power consumption on the receiver side.

[0101] The described features can be implemented in digital electronic circuits, or in computer hardware, firmware, software, or a combination thereof. The apparatus can be tangibly embodied in an information carrier (e.g., in a machine-readable storage device) for execution by a programmable processor in a computer program product; and the method steps can be performed by the programmable processor executing instruction programs to perform the functions of the described implementation by manipulating input data and generating output. The described features can advantageously be implemented in one or more computer programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions from a data storage system, at least one input device, and at least one output device, and to transmit data and instructions to the data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used directly or indirectly in a computer to perform an activity or produce a result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0102] While this disclosure contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope that may be claimed, but rather as descriptions of features specific to particular implementations of a particular invention. Some features described in this disclosure in the context of individual implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations. Furthermore, although features may be described above as functioning in certain combinations and even initially claimed in this way, in some cases, one or more features from the claimed combination may be removed from the combination, and the claimed combination may involve sub-combinations or variations of sub-combinations.

[0103] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order, or to perform all the illustrated operations in order to achieve the desired result.

Claims

1. A method for improving low-density parity-check rate matching, i.e., LDPC rate matching, the method comprising: Add the LDPCExtra symbol to improve decoding performance; as well as Optimize the pre-padding factor before forward error correction (FEC) to reduce the number of padding bits.

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