Methds and systems for payload balancing in wireless communication

Abstract

The present invention is directed to wireless communication methods and systems. In specific embodiments, a rate-matching mechanism focusing on puncturing in LDPC coding is provided to match the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols to the encoded payload size. Puncturing, which is used to trim the size of encoded LDPC codeword, will degrade the performance of LDPC. Additional embodiments lead to methods to avoid an over-puncturing situation to improve performance of LDPC with rate-matching for both uplink and downlink communication applications. There are other embodiments as well.

Description

METHDS AND SYSTEMS FOR PAYLOAD BALANCING IN WIRELESS COMMUNICATIONBACKGROUND OF THE INVENTION

[0001] The present invention is directed to wireless communication methods and systems.

[0002] Wireless networking technology, commonly known as WiFi, has been a widely adopted means of communication for devices or network entities such as computers, tablets, smartphones, and other mobile devices to connect to internet. The WiFi standard, also known as IEEE 802.11, is a set of protocols and specifications that define how wireless devices can communicate with each other and with wired networks.

[0003] The development of the WiFi standard began in the 1980s with the formation of the IEEE 802.11 Working Group, which aimed to create a wireless networking standard that could support high data rates and operate in the unlicensed 2.4 GHz frequency band. Over the years, the WiFi standard has undergone numerous revisions and improvements, resulting in the release of various versions such as 802.1 lb, 802. I la, and 802.11g, each offering faster data rates and improved performance. Next-Gen Wi-Fi will be able to provide significant enhancements to several system Key Performance Indicators (KPI) such as throughput and latency when compared to the existing Wi-Fi based on IEEE 802.11 WLAN standards.

[0004] As data rate increases with newer standards and devices, existing techniques become inadequate for the reasons below. New and improved techniques are desired.BRIEF SUMMARY OF THE INVENTION

[0005] The present invention is directed to wireless communication methods and systems. In specific embodiments, a rate-matching mechanism focusing on puncturing in LDPC coding is provided to match the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols to the encoded payload size. Puncturing, which is used to trim the size of encoded LDPC codeword, will degrade the performance of LDPC. Additional embodiments lead to methods to avoid over-puncturing situation to improve performance of LDPC with rat-matching for both uplink and downlink communication applications. There are other embodiments as well.

[0006] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. The ratematching mechanism in LDPC coding is used to match the number of OFDM symbols to the encoded payload size. One general aspect of this disclosure includes a method for wireless communication. The method includes establishing a wireless communication link with a network entity. The wireless communication link is in compliance with a wireless communication protocol. The method also includes determining a code rate for the wireless communication link. Additionally, the method includes calculating a payload size by matching the code rate to a number of data symbols. The method further includes providing a data unit characterized by the payload size. The data unit includes a header section and a symbol section. The symbol section includes a last symbol. Furthermore, the method includes providing an initial quantity and obtaining a final quantity by adjusting the initial quantity until an overpuncturing condition is no longer satisfied. The method includes inserting the final quantity of quarters of symbol to the last symbol. Moreover, the method includes transmitting the data unit.

[0007] Implementations may include one or more of the following features. The method further includes recursively incrementing the initial quantity until the over-puncturing condition is no-longer satisfied. The method includes evaluating an equation for the over-puncturing condition to be false and stop-adding a quarter of symbol to the (new) last symbol. The method may include determining an insertion location for the final quantity of quarters of symbol. The method further include: evaluating an over-puncturing condition after inserting the initial quantity of quarters of symbol to the last symbol; incrementing the initial quantity by one if the over-puncturing condition is true; inserting one more quarter of symbol on top of the last inserted initial quantity of quarters of symbol; re-evaluating the over-puncturing condition every time after inserting one more quarter of symbol until the final quantity is obtained to get the over-puncturing condition false. The method where the data unit, a physical layer protocol data unit (PPDU), includes a number of low-density parity check (LDPC) encoded bits. The method where the data symbols may include orthogonal frequency division multiplexing (OFDM) symbols.

[0008] Another general aspect includes a method for wireless communication. The method includes establishing a wireless communication link with a network entity. The wireless communication link is in compliance with a wireless communication protocol. The method includes determining a code rate for the wireless communication link and calculating a payload size by matching the code rate to a number of data symbols. Additionally, the method includesproviding a data unit characterized by the payload size. The data unit includes a header section and a symbol section. The symbol section includes a last symbol. The method also includes obtaining a resource unit size associated with the wireless communication link. Furthermore, the method includes comparing the resource unit size to a predetermined size. The method further includes adding a first quarter of symbol to the last symbol for the resource unit size exceeding the predetermined size and adding a predetermined number of quarters of symbol to the last symbol for the resource unit size below the predetermined size. Moreover, the method includes transmitting the data unit.

[0009] Implementations may include one or more of the following features. The method may include evaluating an over-puncturing condition, adding a second quarter of symbol upon the over-puncturing condition being true; and determining an insertion location for the second quarter of symbol. Additionally, the method may include evaluating an equation for the overpuncturing condition. The equation includes j^punc > 0.1 x Ncwx LLDPCx (1 — R) AND ^Nsfirt< 1.2 true OR if^punc > 0-3 x NcwX LLDPCx (1 — R) is true, where NpUnc is total number of bits punctured in the data unit, New is total number of bits in a codeword, LLDPC is a length of a low-density parity check (LDPC) codebook, R is the code rate for the wireless communication link, Nshrt is a number of bits each quarter of symbol can accommodate. The method may include determining an insertion location for the first quarter of symbol. The method where the first quarter of symbol complies with an orthogonal frequency division multiplexing (OFDM) format. Further, the method where the wireless communication link may include wireless channels used in either uplink multi-user multipleinput multiple-output (MU-MIMO) or downlink orthogonal frequency division multiple access (OFDMA). Moreover, the method where the transmitting the data unit also includes transmitting a preamble section of the data unit to a receiver, the preamble section indicating a final number of quarters of symbol added to the last symbol, so that the receiver can correctly derive rate-matching parameters for LDPC decoding.

[0010] Yet another general aspect of the present disclosure includes a wireless communication device. The device includes an encoder configured to generate a data unit comprising a header section and a symbol section. The symbol section is capable of holding multiple input symbols including a last symbol. The device also includes a rate-matcher including a puncturing module configured to puncture a partial group of bits from the multiple input symbols, the rate-matcher being configured to match a number of symbols (withpunctured bits being removed) to a code rate for a wireless communication link, to calculate a payload size of the data unit, and to obtain a resource unit size associated with the wireless communication link. Additionally, the device includes an over-puncturing checker configured to compare the resource unit size to a predetermined size. Furthermore, the device includes a quarter- symbol adder configured to add a first quarter of symbol to the last symbol for the resource unit size exceeding the predetermined size or add a predetermined number of quarters of symbol to the last symbol for the resource unit size below the predetermined size. Moreover, the wireless communication device includes a symbol mapper configured to convert all symbols (with punctured bits being removed) in the data unit to a formatted form ready for transmission through the wireless communication link.

[0011] Implementations may include one or more of the following features. The wireless communication device where the quarter- symbol adder further is configured to recursively add one or more quarters of symbol to the last symbol until the over-puncturing checker determines that an equation of the over-puncturing condition is false. The device where the overpuncturing checker is configured to perform an evaluation of the equation of over-puncturing condition. Additionally, the device where the encoder may include a low-density parity check (LDPC) encoder to generate a number of LDPC encoded bits in each data unit (a PPDU) based on data received from a data source. The device where each symbol may comply with an orthogonal frequency division multiplexing (OFDM) format. Furthermore, the device where the wireless communication link may comply to both uplink multi-user multiple-input multipleoutput (MU-MIMO) and downlink orthogonal frequency division multiple access (OFDMA).

[0012] It is to be appreciated that embodiments of the present invention provide many advantages over conventional techniques. Among other things, the methods for payload balancing in wireless communication according to embodiments of the present invention provides effective ways to handle the over-puncturing issue which caused degradation of performance of the LDPC coding rate-matching process in wireless communication link under the previous 802.11 and even the latest 802.1 lax protocols. Additionally, the methods and systems according to the present invention help to reduce signaling overhead. Rate-matching is an essential part of channel coding. As long as a transmitter and a receiver can be interoperated, then both of them may be benefited from the rate-matching mechanism including the ways to handle the over-puncturing issue for tons of payload / MCS / RU tuples in the wireless communication link used by the transmitter and receiver.

[0013] Embodiments of the present invention can be implemented in conjunction with existing systems and processes. For example, the methods for payload balancing according tothe present invention can be used in a wide variety of communication systems, including wireless networks, satellite communications, and optical communication systems. In these systems, the communication device with the rate-matching process according to the present invention is typically performed by a dedicated hardware or software component, which uses the payload / MCS / RU tuples to determine the appropriate rate-matching parameters for each transmission. Additionally, various techniques according to the present invention can be adopted into existing systems via the establishment of next-generation WiFi standards. There are other benefits as well.

[0014] The present invention achieves these benefits and others in the context of known technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure l is a simplified block diagram illustrating a wireless communication device for performing payload balancing operations according to embodiments of the present invention.

[0016] Figure 2 is a simplified block diagram illustrating a mechanism to avoid overpuncturing.

[0017] Figure 3 is a simplified flow diagram illustrating a method for performing payload balancing in wireless communication according to embodiments of the present invention.

[0018] Figure 4 is a simplified flow diagram illustrating another method for performing payload balancing in wireless communication according to embodiments of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention is directed to wireless communication methods and systems. In specific embodiments, a rate-matching mechanism focusing on puncturing in LDPC coding is provided to match the number of orthogonal frequency division multiplexing symbols to the encoded payload size. Puncturing, which is used to trim the size of encoded LDPC codeword, will degrade the performance of LDPC. Additional embodiments lead to methods to avoid the over-puncturing to improve the performance of LDPC with rat-matching for both uplink and downlink communication applications. There are other embodiments as well.

[0020] As mentioned above, various existing techniques are inadequate for new WiFi standards. Among other features, rate-matching is an important aspect of channel coding in wireless communication link based on IEEE 802.11 WLAN standards. Rate-matching mechanisms are used to match the code rate of the low-density parity check (LDPC) code to the channel conditions and the desired error-correction performance. There are various ratematching mechanisms that can be used in LDPC codes, including puncturing, repetition, shortening, and padding. Puncturing is a rate-matching mechanism in which bits are selectively removed from the encoded data to reduce the code rate. This can be useful when the channel conditions are good and a lower code rate is sufficient for achieving the desired error-correction performance. For example, the puncturing mechanism can be useful when the data rate of the transmission is higher than the channel capacity, as it allows the data to be transmitted more efficiently over the channel. However, LPDC performance degradation issues arise when a so- called over-puncturing condition is triggered. In addition, the maximum payload size of the next-generation WiFi standards will increase significantly compared with 802.1 In. Hence, new and improved balancing mechanisms are desired.

[0021] The following description is presented to enable one of ordinary skill in the art to make and use the invention and to incorporate it in the context of particular applications. Various modifications, as well as a variety of uses in different applications, will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments presented but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0022] In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.

[0023] The reader’s attention is directed to all papers and documents which are filed concurrently with this specification, and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification, (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent, orsimilar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0024] Furthermore, any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. Section 112, Paragraph 6. In particular, the use of “step of’ or “act of’ in the Claims herein is not intended to invoke the provisions of 35 U.S.C. 112, Paragraph 6.

[0025] Please note, if used, the labels left, right, front, back, top, bottom, forward, reverse, clockwise, and counterclockwise have been used for convenience purposes only and are not intended to imply any particular fixed direction. Instead, they are used to reflect relative locations and / or directions between various portions of an object.

[0026] Various embodiments of the present invention are implemented for WiFi communication devices. As an example, a WiFi communication device may include, but is not limited to, an antenna, a radio transceiver, a digital signal processor, and a network interface controller. The antenna is responsible for transmitting and receiving the wireless signal. The radio transceiver is responsible for converting the data from the device into a radio signal, and then transmitting it over the airwaves. The radio transceiver is also responsible for receiving incoming radio signals and converting them back into a digital format that can be understood by the device. The digital signal processor is implemented for encoding and decoding the data that is sent and received over the network. The network interface controller is configured for connecting the device to the WiFi network, and for managing the flow of data between the device and the network. As an example, various WiFi communication devices including payload balancing mechanisms are described in further detail below.

[0027] Figure l is a simplified block diagram illustrating a wireless communication device for performing payload balancing operations according to embodiments of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of the ordinary skills in art would recognize many variations, alternatives, and modifications. A transmitter device 100 in a simplified block diagram, as shown in FIG. 1. The transmitter device 100 includes a functional data unit rate-matching module 120, in accordance with certain aspects of the present disclosure, configured to match a number of OFDM symbols to LPDC encoded payload size and implemented as a portion of a network entity with a wireless channel 150. The network entity has a data source 110, which may comprise a database, data storage, a sensor collecting data, or a web app.

[0028] In an embodiment, rate-matching module 120 receives a message from the data source 110. The message may contain a piece of information expressed in a sequence of digital data intended for a receiving device (or destination). Rate-matching module 120 includes an encoder 122 that encodes the message using a suitable modulation and coding scheme (MCS) depending on the configuration defined by the specific network entity. For example, low-density paritycheck (LDPC) codes are one type of MCS that can be used for error correction in communication systems. LDPC codes can provide a high level of error correction performance and are used in a variety of wireless communication systems. After encoding, the message is illustrated in one or more data units each containing a total number of encoded bits. Each data unit often is referred to as a physical layer protocol data unit or PPDU. Each PPDU can accommodate a total number of Navbits encoded bits distributed in multiple sections, like, a preamble section, a header section, and a symbol section. The preamble section typically contains a known sequence of bits that is used by the receiver to synchronize with the transmitter and identify the start of the data transmission. The header section typically contains information about the data being transmitted, such as the destination address, the length of the data, and any error-correction coding information. The symbol section of the PPDU includes multiple Orthogonal Frequency Division Multiplexing (OFDM) symbols carrying LDPC codewords containing the actual data being transmitted.

[0029] Rate-matching is a process used in communication systems to adjust the data rate of an LDPC-encoded data unit to match the available bandwidth or other resources. In an LDPC- encoded data unit, the rate-matching process would typically be performed on the symbol portion of the data unit. Rate-matching module 120 of FIG. 1 includes a rate-matching with puncturing module 124 to ensure that the LDPC encoded data unit can be transmitted efficiently and with a high level of error-correction performance. In particular, the rate-matching with puncturing module 124 performs a trimming operation to puncture out a certain number of NpUnc bits so that the size of the encoded LDPC codeword is trimmed. By removing the NpUnc punctured bits from the encoded data the amount of redundant information added by the LDPC code is adjusted to match the available bandwidth or other resources. Yet, removing NpUnc punctured bits from the encoded data unit leads to a reduction in data rate, resulting in a certain degree of degradation of the performance of LDPC coding. In certain situations, the overpuncturing issue needs to be avoided in wireless communication to maintain a high level of error-correction performance.

[0030] Figure 2 is a simplified block diagram illustrating a mechanism to avoid overpuncturing. This diagram is merely an example, which should not unduly limit the scope of theclaims. One of the ordinary skills in art would recognize many variations, alternatives, and modifications. To the left of FIG. 2, it shows a graphical illustration of an LDPC encoded data unit PPDU containing a head section (the preamble section is not shown) followed by a symbol section. The symbol section contains multiple OFDM symbols being used to carry the LDPC encoded bits (e.g., each symbol carries an LDPC codeword) and the last one is used to carry only a first quarter of OFDM symbol to give a total number of Navbitsencoded bits. When over-puncturing conditions are triggered, it means puncturing exceeds a threshold such that the performance of LDPC is degraded too much. The rate-matching mechanism would facilitate adding a quarter of OFDM symbol on top of the Navbitsto accommodate the encoded LDPC codewords such that over-puncturing will not happen. To the right of FIG. 2, one more quarter of symbol is added on top of the previous first quarter of symbol; it shows two quarters of symbol taking the last symbol space. In this way, the total number Navbitsof bits becomes larger and the PPDU can accommodate more encoded bits, hopefully retaining rate-matching in LDPC coding.

[0031] In order to detect whether over-puncturing conditions are triggered, rate-matching module 120 of FIG. 1 includes an over-puncturing checker 126 to evaluate existing coding parameters such as the payload size associated with the data unit, and available bandwidth such as the resource unit size associated with the wireless communication link in which the transmitter device 100 is stationed. A common rule to define the over-puncturing conditions is to check whether the following equation (Eq. 1) is true: ^punc > 0.1 D ^Nsbrt < 1.2 Npunc > 0.3true,where NpUnc is total number of bits punctured in the data unit, New is total number of bits in a codeword, LLDPC is a length of a low-density parity check (LDPC) codebook, R is the code rate for the wireless communication link, Nshrt is a number of bits each quarter of symbol can accommodate. (Eq. l) has two conditions. If over-puncturing checker 126 evaluates (Eq.l) and determines either of the two conditions be true, the over-puncturing is triggered.

[0032] Referring to FIG. 1, rate-matching module 120 includes a quarter-symbol adder 128 configured to add one quarter of symbol on top of the Navbits at a location of the last symbol (see FIG. 2) to accommodate more encoded LDPC codewords. The issue is after (Eq.1) is triggered and a quarter of OFDM symbol is added, (Eq.1) is still being triggered as there still are many payload / MCS / RU tuples fall into the over-puncturing situation. Yet, unlike traditionally only one quarter of symbol is added which may not be enough to fully solve theover-puncturing issue, quarter-symbol adder 128 in an embodiment of the present invention is configured to add each quarter of OFDM symbol recursively by following a routine below:Initializing a new rate-matching parameter, number of quarters of OFDM symbol added, as n quater Symbol = 0;While (Eq. l) is TRUEAdd a quarter of OFDM symbol on top of Navbitsn quater Symbol = n quater Symbol + 1; re-calculate NpUnc and evaluate (Eq. 1);If (Eq. 1) is falseRecord n quater Symbol;Break;ElseContinue.End

[0033] In the embodiment, quarter-symbol adder 128 keeps adding quarters of symbol (i.e., multiple quarters of OFDM symbol can be added) until the end so (Eq. 1) is no longer satisfied. Therefore, the over-puncturing issue would be eliminated for sure by rate-matching module 120. In contrast, existing systems do not do anything after adding just one quarter of symbol when there are many conditions triggered (Eq. 1). The information of the final recorded number of quarters of OFDM symbol added, n quater Symbol, will be indicated in the preamble section of the PPDU and sent to a receiver by the transmitter 100 that implements rate-matching module 120. The receiver received this data unit and then can correctly derive the ratematching parameters used for LDPC decoding.

[0034] During the evaluation, it was found that n quater Symbol used in the example shown above can be quite large (such as 68, which needs ceil(log2(68)) = 7 bits to indicate it in the preamble. In another embodiment, quarter- symbol adder 128 is configured to add one larger quantity of quarters of symbol first then add one quarter of symbol recursively so that a smaller number of n quater Symbol is required to reduce signaling overhead. Specifically, quartersymbol adder 128 performs its operation by following the routine below:Initializing a new parameter, the number of “quarters of OFDM symbol added”, as n quater Symbol = 0;Define the “number of quarters of OFDM symbol incremental step size” as n quater step (>= 1);While (Eq. l) is TRUEAdd n quater step quarters of OFDM symbol on top of Navbitsn quater Symbol = n quater Symbol + 1; re-calculate NpUnc and evaluate (Eq. 1); If (Eq. 1) is falseRecord n quater Symbol;Break;ElseContinue.End

[0035] In the embodiment, the n quater step can either be predefined or configurable and indicated together with n quater Symbol in the preamble of the data unit to be sent to a receiver. Therefore, the transmitter 100 that implements rate-matching module 120 can add more quarters of OFDM symbol to get out of the over-puncturing evaluation loop faster such that a smaller number of n quater Symbol is required.

[0036] In yet another embodiment, adding either one quarter of OFDM symbol or multiple quarters of OFDM symbol depends on the resource unit (RU) size associated with the wireless communication link (or wireless channel bandwidth and other resources). Quarter- symbol adder 128 is configured to evaluate the RU size of the wireless communication link thereof by comparing the RU size to a predetermined size. For example, a 242-tone is predetermined RU size. If the RU size > 242-tone, it is considered to be a larger RU size and quarter- symbol adder 128 then add one quarter of OFDM symbol. If the RU size < 242-tone, quarter- symbol adder 128 then add n quater step quarters of OFDM symbol. In other words, quarter-symbol adder 128 performs its operation of adding different sizes of quarters depending on RU size by following the routine below:While (Eq.l) is TRUE If RU size >=242Add a quarter of OFDM symbol on top of NavbitsElseAdd n quater step quarters of OFDM symbol on top of Navbitsendn quater Symbol = n quater Symbol + 1; re-calculate NpUnc and evaluate (Eq. 1); If (Eq. 1) is falseRecord n quater Symbol;Break;ElseContinue.End

[0037] In all embodiments, quarter- symbol adder 128 is configured to insert the quarter of symbol to a location at the edge of the last symbol. While completion of adding one quarter symbol moves the edge of the last symbol to next quarter symbol location which would be the location for inserting one more quarter of symbol if the adding operation continues as needed. Similarly, as a larger quantity of n quater step quarters of symbol are added, the edge of a new last symbol may be moved further over several full symbols or optionally plus some quarters of symbol in the new last symbol. Still, any newly added quarter of symbol will then be inserted into the newly established edge location of the new last symbol.

[0038] Referring to FIG. 1 again, rate-matching module 120 further includes a symbol mapper 129 configured to convert all encoded bits in those OFDM symbols in the data unit to a transmittable form. The symbol mapper 129 maps all input data symbols, after matching the number of input symbols (with punctured bits removed) to all available (including added quarters of symbol) symbol sections of the data unit, to generate a sequence of digital signals. In an OFDM system, a digital signal is divided into multiple subcarrier signals, which are then transmitted simultaneously over different frequency bands. This allows the input data to be transmitted over the different frequency bands. Further, the transmitter device 100 includes Tx chains 140 to modulate, amplify, and otherwise process the digital signals in different frequency bands following a specific modulation scheme. The Tx chains 140 outputs multiple divisional RF signals for transmission through multiple wireless channels 150 to a receiver. Note, all ratematching parameters, such as the number of punctured bits, the number of quarters of OFDM symbol added, the number of n quater step, etc. will be indicated in the data unit and transmitted to the receiver.

[0039] Figure 3 is a simplified flow diagram illustrating a method for performing payload balancing in wireless communication according to embodiments of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of the ordinary skills in art would recognize many variations, alternatives, and modifications. Asshown in FIG. 3, method 300 executes multiple steps to perform payload balancing for LDPC codes in wireless communications. Step 310 of method 300 performs establishing a wireless communication link. Optionally, the wireless communication link is referred to one or more wireless channels with a network entity. The wireless communication link complies with a wireless communication protocol. The network entity includes a device or system that is capable of transmitting or receiving data over a network. Examples of network entities include computers, routers, switches, servers, and other devices that are connected to a network. These entities are the fundamental building blocks of a network, and they are responsible for transmitting, receiving, and processing data in order to facilitate communication between different devices. For example, the wireless communication link is referring one or more WiFi channels configured to transmit / receive wireless signals with 802.11 communication protocol between the network entities in a local area network.

[0040] Step 312 of method 300 includes an operation for determining a code rate for encoding data and transmitting the data through the wireless communication link. The code rate refers to the ratio of the number of information bits to the total number of bits in a transmitted code. A higher code rate indicates that a larger proportion of the transmitted bits are carrying information, while a lower code rate indicates that more of the transmitted bits are used for error correction. In general, a higher code rate provides better error correction performance, but it also results in a lower data rate due to the increased overhead. For a communication system complying with LDPC codes, the code rate is a trade-off between data rate and error correction performance of the LDPC coding.

[0041] In other words, the code rate should be balanced or matched to consider payload size as well as channel resources. Step 314 of method 300 includes calculating a payload size by matching the code rate to a number of data symbols that a data unit can accommodate. Each data symbol is a sequence of encoded bits arranged in a codeword. A specific feature of the method includes that the data symbols comprise orthogonal frequency division multiplexing (OFDM) symbols. Step 316 of method 300 further includes providing a data unit characterized by the payload size. The data unit includes a symbol section containing a header section and a symbol section including a last symbol (section). The symbol section contains space to hold multiple symbols optionally including a quarter of symbol in the last symbol (section). A specific feature of the method includes that the data unit includes a number of low-density parity check (LDPC) encoded bits.

[0042] Optionally, some encoded bits are punctured (removed) from the symbols in order to achieve rate-matching. Rate-matching with puncturing is a technique used in the transmissionof Orthogonal Frequency Division Multiplexing (OFDM) symbols to maintain the orthogonality of the carriers while allowing for a higher data rate. It is a form of rate-matching in which some of the redundancy bits that are added to the data are removed, or "punctured," before transmission, allowing for more data to be transmitted within the same bandwidth. But, the higher-rate transmission using rate-matching with puncturing, especially with over-puncturing issues, is achieved at the expense of reduced error-correction performance.

[0043] In the case of over-puncturing being triggered, method 300 includes performing the following operations to achieve payload balancing and avoid over-puncturing in wireless communication. Step 318 is to provide an initial quantity (or a number). Step 320 is to obtain a final quantity by adjusting the initial quantity until an over-puncturing condition is no longer satisfied. Step 322 is to insert the final quantity of quarters of symbol into the last symbol. In a specific embodiment, the initial quantity (number) is 1 provided in step 318. Then 1 quarter of symbol is added to the last symbol and the over-puncturing condition is evaluated. If the overpuncturing condition is still satisfied, the initial number 1 is adjusted to 2. Then one more quarter of symbol (making 2 the total number) is added to the last symbol (which has been added 1 quarter of symbol already). Again, the over-puncturing condition is evaluated. If it is still true, the operation of adding one quarter of symbol to the last symbol is recursively performed. A specific feature of the method includes that the over-puncturing condition is triggered by (Eq. 1), in which either of two inequalities is true. When both inequalities are false, the over-puncturing condition is avoided.

[0044] Alternatively, the initial quantity may be a large value, for example, 10. Step 320 will perform to obtain a final quantity (>10) by adding one more quarter of symbol each time recursively until the over-puncturing condition is false. After all, the final quantity of quarters of symbol are added to the last symbol and the final quantity will be recorded in (the preamble section of) the data unit. A specific feature of step 322 includes determining an insertion location for the final quantity of quarters of symbol as the edge of the last symbol keeps moving up with each quarter of symbol being added. The method ensures the elimination of the overpuncturing issues in the data transmission through the wireless communication link. Method 300 includes step 324 for transmitting the data unit through the wireless communication link after the rate-matching by puncturing redundant bits and adding the final quantity of quarters of symbol in the last symbol (section) of the data unit to avoid over-puncturing.

[0045] Figure 4 is a simplified flow diagram illustrating another method for performing payload balancing in wireless communication according to embodiments of the present invention. This diagram is merely an example, which should not unduly limit the scope of theclaims. One of the ordinary skills in art would recognize many variations, alternatives, and modifications. As shown in FIG. 4, method 400 includes step 412 for establishing a wireless communication link. The wireless communication link may be a WiFi channel in compliance with existing communication protocols. Step 414, method 400 performs one or more operations to determine a code rate for the wireless communication link. Step 416, method 400 performs one or more operations to calculate a payload size by matching the code rate to a number of data symbols. Each data symbol is a sequence of encoded bits arranged in a codeword. A specific feature of the method includes that the data symbols comprise orthogonal frequency division multiplexing (OFDM) symbols. Another specific feature of the method includes that each codeword includes a number of low-density parity check (LDPC) encoded bits.

[0046] Referring to FIG. 4, step 418 of method 400 performs one or mere operations to provide a data unit characterized by the payload size. The data unit includes a header section and a symbol section. The symbol section is configured to hold multiple data symbols including data in the last symbol. The last symbol may hold only a quarter of data symbol.

[0047] Step 420 of method 400 further performs one or more operations to obtain a resource unit size associated with the wireless communication link. Typically, the resource unit size corresponds to the bandwidth available for transmitting LDPC encoded bits with a code rate through a corresponding wireless channel. Therefore, the code rate matching the number of data symbols in the data unit will be balanced through a dependence on the resource unit size. In an embodiment, the rate-matching is specifically associated with redundant bits puncturing operation. Rate-matching with puncturing is a technique used in the transmission of Orthogonal Frequency Division Multiplexing (OFDM) symbols to maintain the orthogonality of the carriers while allowing for a higher data rate. It is a form of rate-matching in which some of the redundancy bits that are added to the data are removed, or "punctured," before transmission, allowing for more data to be transmitted within the same bandwidth. But, the higher-rate transmission using rate-matching with puncturing, especially with over-puncturing issues, is achieved at the expense of reduced error-correction performance. Step 422 of method 400 then performs one or more operations to compare the resource unit size to a predetermined size, which evaluates the resource unit size being a large one or a small one. Based on the evaluation, step 424 of method 400 performs an operation to add a first quarter of symbol to the last symbol for the resource unit size exceeding the predetermined size. In some examples, the predetermined size is 242 tone which distinguishes a larger resource unit or a smaller one.

[0048] A feature of the method includes operations for evaluating an over-puncturing condition; adding a second quarter of symbol upon the over-puncturing condition being true;determining an insertion location for the second quarter of symbol. Again, the over-puncturing condition is set by (Eq. 1). Another feature of the method includes recursively adding one more quarter of symbol once the evaluation of the over-puncturing condition is still satisfied or stopping once the (Eq. 1) is false. Yet another feature of the method includes operations for determining an insertion location for the first quarter of symbol. Usually, the insertion location is selected to be an edge of the last symbol (which may be one quarter of symbol). As the first quarter of symbol is inserted to the edge, the edge of the (new) last symbol becomes the edge of the second quarter of symbol just added. Still, another feature of the method includes that the first quarter of symbol complies with an orthogonal frequency division multiplexing (OFDM) format.

[0049] In an alternative case for a smaller resource unit size, step 426 of method 400 performs an operation to add a predetermined number of quarters of symbol to the last symbol for the resource unit size below the predetermined size. A feature of the method includes evaluating (Eq. 1) after adding the predetermined number of quarters of symbol to the last symbol and stopping if (Eq.l) becomes false. Or, if (Eq. 1) is still satisfied, recursively adding one more quarter of symbol to the last symbol and evaluating (Eq. 1); and stopping until (Eq. 1) is false to avoid the over-puncturing issue in the rate-matching compliant data unit.

[0050] Step 428 of method 400 then performs transmitting the data unit through the wireless communication link with rate-matching payload balance and resource unit size. A feature of the method includes that the wireless communication link can be disposed of in either uplink multiuser multiple-input multiple-output (MU-MIMO) or downlink orthogonal frequency division multiple access (OFDMA). Another feature of the method includes that transmitting the data unit to a receiver also includes transmitting a preamble section of the data unit to the receiver. The preamble section indicates a final number of quarters of symbol added to the last symbol so that the receiver can correctly derive rate-matching parameters for LDPC decoding. As long as a transmitter and a receiver can be inter-operatable, then both of them need to follow standard which includes rate-matching with puncturing mechanism according to the methods of the present invention.

[0051] While the above is a full description of the specific embodiments, various modifications, alternative constructions and equivalents may be used. Therefore, the above description and illustrations should not be taken as limiting the scope of the present invention which is defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for wireless communication, comprising: establishing a wireless communication link with a network entity, the wireless communication link being in compliance with a wireless communication protocol; determining a code rate for the wireless communication link; calculating a payload size by matching the code rate to a number of data symbols; providing a data unit characterized by the payload size, the data unit comprising a header section and a symbol section, the symbol section comprising a last symbol; providing an initial quantity; obtaining a final quantity by adjusting the initial quantity until an overpuncturing condition is no longer satisfied; inserting the final quantity of quarters of symbol to the last symbol; and transmitting the data unit.

2. The method of claim 1 further comprising recursively incrementing the initial quantity.

3. The method of claim 1 further comprising evaluating an equation for the over-puncturing condition to be false.

4. The method of claim 1 further comprising determining an insertion location for the final quantity of quarters of symbol.

5. The method of claim 2 further comprising: evaluating an over-puncturing condition after inserting the initial quantity of quarters of symbol to the last symbol; incrementing the initial quantity by one if the over-puncturing condition is true; inserting one more quarter of symbol on top of the last inserted initial quantity of quarters of symbol; re-evaluating the over-puncturing condition every time after inserting one more quarter of symbol until the final quantity is obtained to get the over-puncturing condition false.

6. The method of claim 1 wherein the data unit comprises a number of low- density parity check (LDPC) encoded bits.

7. The method of claim 1 wherein the data symbols comprise orthogonal frequency division multiplexing (OFDM) symbols.

8. A method for wireless communication, comprising: establishing a wireless communication link with a network entity, the wireless communication link being in compliance with a wireless communication protocol; determining a code rate for the wireless communication link; calculating a payload size by matching the code rate to a number of data symbols; providing a data unit characterized by the payload size, the data unit comprising a header section and a symbol section, the symbol section comprising a last symbol; obtaining a resource unit size associated with the wireless communication link; comparing the resource unit size to a predetermined size; adding a first quarter of symbol to the last symbol for the resource unit size exceeding the predetermined size; adding a predetermined number of quarters of symbol to the last symbol for the resource unit size below the predetermined size; and transmitting the data unit.

9. The method of claim 8 further comprising: evaluating an over-puncturing condition; adding a second quarter of symbol upon the over-puncturing condition being true; and determining an insertion location for the second quarter of symbol.

10. The method of claim 9 further comprising evaluating an equation for the over-puncturing condition, the equation comprising ^punc > 0.1 D ^Nshrt < 1.2 true OR if^punc > 0-3true, wherein NpUnc is total number of bits punctured in the data unit, New is total number of bits in a codeword, LLDPC is a length of a low-density parity check (LDPC) codebook, R is the code rate for the wireless communication link, Nshrt is a number of bits each quarter of symbol can accommodate.

11. The method of claim 8 further comprising determining an insertion location for the first quarter of symbol.

12. The method of claim 8 wherein the first quarter of symbol complies with an orthogonal frequency division multiplexing (OFDM) format.

13. The method of claim 8 wherein the wireless communication link comprises wireless channels used in either uplink multi-user multiple-input multiple-output (MU-MIMO) or downlink orthogonal frequency division multiple access (OFDMA).

14. The method of claim 8 wherein the transmitting the data unit comprises also transmitting a preamble section of the data unit to a receiver, the preamble section indicating a final number of quarters of symbol added to the last symbol, so that the receiver can correctly derive rate-matching parameters for LDPC decoding.

15. A wireless communication device comprising: an encoder configured to generate a data unit comprising a header section and a symbol section, the symbol section being capable of holding multiple input symbols including a last symbol; a rate-matcher comprising a puncturing module configured to puncture a partial group of bits from the multiple input symbols, the rate-matcher being configured to match a number of symbols (with punctured bits being removed) to a code rate for a wireless communication link, to calculate a payload size of the data unit, and to obtain a resource unit size associated with the wireless communication link; an over-puncturing checker configured to compare the resource unit size to a predetermined size; a quarter- symbol adder configured to add a first quarter of symbol to the last symbol for the resource unit size exceeding the predetermined size or add a predetermined number of quarters of symbol to the last symbol for the resource unit size below the predetermined size; and a symbol mapper configured to convert all symbols (with punctured bits being removed) in the data unit to transmittable form.

16. The wireless communication device of claim 15 wherein the quartersymbol adder further is configured to recursively add one or more quarters of symbol to the last symbol until the over-puncturing checker determines that an equation of over-puncturing condition is false.

17. The wireless communication device of claim 15 wherein the overpuncturing checker performs evaluation of an equation of over-puncturing condition, the equation comprising j^punc > 0.1 x Ncwx LLDPCx (1 — R) AND ^Nsfirt< 1.2 true OR if^punc > 0-3 x NcwX LLDPCx (1 — R) is true, wherein NpUnc is total number of bits punctured in the data unit, New is total number of bits in a codeword, LLDPC is a length of a low-density parity check (LDPC) codebook, R is the code rate for the wireless communication link, Nshrt is a number of bits each quarter of symbol can accommodate.

18. The wireless communication device of claim 15 wherein the encoder comprises a low-density parity check (LDPC) encoder to generate a number of LDPC encoded bits in each data unit.

19. The wireless communication device of claim 15 wherein each symbol or a quarter of symbol complies to an orthogonal frequency division multiplexing (OFDM) format.

20. The wireless communication device of claim 15 complies with both uplink multi-user multiple-input multiple-output (MU-MIMO) and downlink orthogonal frequency division multiple access (OFDMA).

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