WO2018216922A1

WO2018216922A1 - Multi-user transmission method in wireless lan system and device therefor

Info

Publication number: WO2018216922A1
Application number: PCT/KR2018/005150
Authority: WO
Inventors: 윤선웅; 김진민; 박성진; 최진수
Original assignee: 엘지전자 주식회사
Priority date: 2017-05-26
Filing date: 2018-05-03
Publication date: 2018-11-29

Abstract

A method by which a first station (STA) performs multi-user transmission for multiple second STAs in a wireless LAN system comprises: determining the maximum number of single carrier (SC) symbol blocks among the number of SC symbol blocks for a low density parity check (LDPC) coded bit for each user; and transmitting, to the multiple second STAs, a signal in which a pad bit for each user, determined on the basis of the maximum number of SC symbol blocks and the LDPC coded bit for each user, are concatenated.

Description

Multi-user transmission method in wireless LAN system and apparatus therefor

The following description is about a multi-user transmission method of a station and a device therefor in a WLAN system.

The standard for WLAN technology is being developed as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b are described in 2.4. Using unlicensed band at GHz or 5 GHz, IEEE 802.11b provides a transmission rate of 11 Mbps and IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE 802.11g applies orthogonal frequency-division multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n applies multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission rate of 300 Mbps for four spatial streams. IEEE 802.11n supports channel bandwidths up to 40 MHz, in this case providing a transmission rate of 600 Mbps.

The WLAN standard uses a maximum of 160MHz bandwidth, supports eight spatial streams, and supports IEEE 802.11ax standard through an IEEE 802.11ac standard supporting a speed of up to 1Gbit / s.

Meanwhile, IEEE 802.11ad defines performance enhancement for ultra-high throughput in the 60 GHz band, and IEEE 802.11ay for channel bonding and MIMO technology is introduced for the first time in the IEEE 802.11ad system.

The present invention proposes a method for performing multi-user transmission by a station operating in a single carrier mode and an apparatus therefor.

In one aspect of the present invention for solving the above problems, in a wireless LAN (WLAN) system, a first station (STA) in a multi-user (MU) transmission method for a plurality of second STA Determining a maximum number of SC symbol blocks among the number of single carrier symbol blocks for low density parity check (LDPC) coded bits for each user; And transmitting to the plurality of second STAs a signal in which pad bits for each user and LDPC coded bits for each user are determined based on the maximum number of SC symbol blocks. We propose a multi-user transmission method.

In the above configuration, the number of SC symbol blocks for each user includes the LDPC codeword length for each user, the total number of lDPC codewords for each user, the number of consecutive 2.16 GHz channels through which the signal is transmitted, and the SC symbol blocks. It may be determined based on the number of symbols and the number of coded bits per symbol for all spatial streams for each user.

In addition, the LDPC coded bit for each user may be generated by concatenating each user's data pad bit and each user's data bit determined based on the total number of LDPC codeweeds for each user.

In this case, the first STA may correspond to a personal basic service set central point / access point (PCP / AP).

The signal may also be transmitted through a channel aggregated 2.16 GHz + 2.16 GHz channel or a 4.32 GHz + 4.32 GHz channel.

In another aspect of the present invention for solving the above problems, a station apparatus for transmitting a signal in a WLAN system, having one or more RF (Radio Frequency) chain, and a plurality of other station apparatus A transceiver configured to transmit and receive a signal; And a processor connected to the transceiver, the processor configured to process a signal transmitted / received with the plurality of other station devices, wherein the processor comprises: low density parity check (LDPC) coded bits for each user Determining a maximum number of SC symbol blocks among the number of SC (Single Carrier) symbol blocks; And transmitting a signal concatenated with each user pad bit and each user LDPC coded bit determined based on the maximum number of SC symbol blocks to the plurality of other station devices. Propose station equipment.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

Through the above configuration, the station operating in the SC mode according to the present invention can perform multi-user transmission.

In particular, according to the present invention, for multi-user Physical Protocol Data Unit (PPDU) transmission, all the user's PPDUs can be aligned in time dimension.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings appended hereto are for the purpose of providing an understanding of the present invention and for illustrating various embodiments of the present invention and for describing the principles of the present invention in conjunction with the description thereof.

1 is a diagram illustrating an example of a configuration of a WLAN system.

2 is a diagram illustrating another example of a configuration of a WLAN system.

3 is a diagram for describing a channel in a 60 GHz band for explaining a channel bonding operation according to an embodiment of the present invention.

4 is a diagram illustrating a basic method of performing channel bonding in a WLAN system.

5 is a view for explaining the configuration of the beacon interval.

6 is a diagram for explaining a physical configuration of an existing radio frame.

7 and 8 are views for explaining the configuration of the header field of the radio frame of FIG.

9 illustrates a PPDU structure applicable to the present invention.

10 is a diagram schematically illustrating a PPDU structure applicable to the present invention.

11 is a flowchart illustrating a method in which a PCP / AP performs MU transmission according to an embodiment of the present invention.

12 is a view for explaining an apparatus for implementing the method as described above.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention.

There may be various mobile communication systems to which the present invention is applied. Hereinafter, the WLAN system will be described in detail as an example of the mobile communication system.

1. One. 무선랜(Wireless LAN, Wireless LAN, WLANWLAN ) 시스템) system

1.1. WLAN System General

1 is a diagram illustrating an example of a configuration of a WLAN system.

As shown in FIG. 1, the WLAN system includes one or more basic service sets (BSSs). A BSS is a set of stations (STAs) that can successfully synchronize and communicate with each other.

An STA is a logical entity that includes a medium access control (MAC) and a physical layer interface to a wireless medium. The STA is an access point (AP) and a non-AP STA (Non-AP Station). Include. The portable terminal operated by the user among the STAs is a non-AP STA, and when referred to simply as an STA, it may also refer to a non-AP STA. A non-AP STA may be a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, or a mobile subscriber. It may also be called another name such as a mobile subscriber unit.

The AP is an entity that provides an associated station (STA) coupled to the AP to access a distribution system (DS) through a wireless medium. The AP may be called a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), a personal basic service set central point / access point (PCP / AP), or a site controller.

BSS can be divided into infrastructure BSS and Independent BSS (IBSS).

The BBS shown in FIG. 1 is an IBSS. The IBSS means a BSS that does not include an AP. Since the IBSS does not include an AP, access to the DS is not allowed, thereby forming a self-contained network.

The BSS shown in FIG. 2 is an infrastructure BSS. Infrastructure BSS includes one or more STAs and APs. In the infrastructure BSS, communication between non-AP STAs is performed via an AP. However, when a direct link is established between non-AP STAs, direct communication between non-AP STAs is also possible.

As shown in FIG. 2, a plurality of infrastructure BSSs may be interconnected through a DS. A plurality of BSSs connected through a DS is called an extended service set (ESS). STAs included in the ESS may communicate with each other, and a non-AP STA may move from one BSS to another BSS while communicating seamlessly within the same ESS.

The DS is a mechanism for connecting a plurality of APs. The DS is not necessarily a network, and there is no limitation on the form if it can provide a predetermined distribution service. For example, the DS may be a wireless network such as a mesh network or a physical structure that connects APs to each other.

Based on the above, the channel bonding method in the WLAN system will be described.

1.2. Channel in WLAN system Bonding

As shown in FIG. 3, four channels may be configured in the 60 GHz band, and a general channel bandwidth may be 2.16 GHz. The ISM bands available from 60 GHz (57 GHz to 66 GHz) may be defined differently in different countries. In general, channel 2 of the channels shown in FIG. 3 may be used in all regions and may be used as a default channel.

Channels

2 and 3 can be used in most of the designations except Australia, which can be used for channel bonding. However, a channel used for channel bonding may vary, and the present invention is not limited to a specific channel.

The example of FIG. 4 illustrates the operation of 40 MHz channel bonding by combining two 20 MHz channels in an IEEE 802.11n system. For IEEE 802.11ac systems, 40/80/160 MHz channel bonding will be possible.

The two exemplary channels of FIG. 4 include a primary channel and a secondary channel, so that the STA may examine the channel state in a CSMA / CA manner for the primary channel of the two channels. If the secondary channel is idle for a predetermined time (e.g. PIFS) at the time when the primary channel idles for a constant backoff interval and the backoff count becomes zero, the STA is assigned to the primary channel and Auxiliary channels can be combined to transmit data.

However, when channel bonding is performed based on contention as illustrated in FIG. 4, channel bonding may be performed only when the auxiliary channel is idle for a predetermined time at the time when the backoff count for the primary channel expires. Therefore, the use of channel bonding is very limited, and it is difficult to flexibly respond to the media situation.

Accordingly, an aspect of the present invention proposes a method in which an AP transmits scheduling information to STAs to perform access on a scheduling basis. Meanwhile, another aspect of the present invention proposes a method of performing channel access based on the above-described scheduling or on a contention-based basis independently of the above-described scheduling. In addition, another aspect of the present invention proposes a method for performing communication through a spatial sharing technique based on beamforming.

1.3. Beacons Configure interval

5 is a view for explaining the configuration of the beacon interval.

In an 11ad based DMG BSS system, the time of the medium may be divided into beacon intervals. Lower periods within the beacon interval may be referred to as an access period. Different connection intervals within one beacon interval may have different access rules. The information about the access interval may be transmitted to the non-AP STA or the non-PCP by an AP or a personal basic service set control point (PCP).

As shown in FIG. 5, one beacon interval may include one beacon header interval (BHI) and one data transfer interval (DTI). As shown in FIG. 4, the BHI may include a Beacon Transmission Interval (BTI), an Association Beamforming Training (A-BFT), and an Announcement Transmission Interval (ATI).

The BTI means a section in which one or more DMG beacon frames can be transmitted. A-BFT refers to a section in which beamforming training is performed by an STA that transmits a DMG beacon frame during a preceding BTI. ATI means a request-response based management access interval between PCP / AP and non-PCP / non-AP STA.

Meanwhile, as shown in FIG. 5, one or more Content Based Access Period (CBAP) and one or more Service Periods (SPs) may be allocated as data transfer intervals (DTIs). Although FIG. 5 shows an example in which two CBAPs and two SPs are allocated, this is merely an example and need not be limited thereto.

Hereinafter, the physical layer configuration in the WLAN system to which the present invention is applied will be described in detail.

1.4. Physical Layer Configuration

In the WLAN system according to an embodiment of the present invention, it is assumed that three different modulation modes may be provided.

PHYPHY	MCSMCS	NoteNote
Control PHYControl PHY	00
Single carrier PHY(SC PHY)Single carrier PHY (SC PHY)	1, ..., 1225, ..., 311, ..., 1225, ..., 31	(low power SC PHY)(low power SC PHY)
OFDM PHYOFDM PHY	13, ..., 2413, ..., 24

Such modulation modes can be used to meet different requirements (eg, high throughput or stability). Depending on your system, only some of these modes may be supported.

It is assumed that all DMG (Directional Multi-Gigabit) physical layers commonly include fields as shown in FIG. 6. However, there may be a difference in the method of defining individual fields and the modulation / coding method used according to each mode.

As shown in FIG. 6, the preamble of the radio frame may include a Short Training Field (STF) and a Channel Estimation (CE). In addition, the radio frame may include a header and a data field as a payload and optionally a training field for beamforming.

Specifically, FIG. 7 illustrates a case in which a single carrier (SC) mode is used. In the SC mode, a header indicates information indicating an initial value of scrambling, a modulation and coding scheme (MCS), information indicating a length of data, and additional information. Information indicating the presence of a physical protocol data unit (PPDU), packet type, training length, aggregation, beam training request, last RSSI (Received Signal Strength Indicator), truncation, header check sequence (HCS), etc. Information may include In addition, as shown in FIG. 7, the header has 4 bits of reserved bits, which may be used in the following description.

8 illustrates a specific configuration of a header when the OFDM mode is applied. The OFDM header includes information indicating an initial value of scrambling, an MCS, information indicating a length of data, information indicating whether an additional PPDU exists, packet type, training length, aggregation, beam training request, last RSSI, truncation, and HCS. (Header Check Sequence) may be included. In addition, as shown in FIG. 8, the header has 2 bits of reserved bits, and in the following description, such reserved bits may be utilized as in the case of FIG.

As described above, the IEEE 802.11ay system is considering introducing channel bonding and MIMO technology for the first time in the existing 11ad system. To implement channel bonding and MIMO in 11ay, a new PPDU structure is needed. That is, the existing 11ad PPDU structure has limitations in supporting legacy terminals and implementing channel bonding and MIMO.

To this end, a new field for the 11ay terminal may be defined after the legacy preamble and the legacy header field for supporting the legacy terminal. Here, channel bonding and MIMO may be supported through the newly defined field.

9 illustrates a PPDU structure according to one preferred embodiment of the present invention. In FIG. 9, the horizontal axis may correspond to the time domain and the vertical axis may correspond to the frequency domain.

When two or more channels are bonded, a frequency band (eg, 400 MHz band) of a predetermined size may exist between frequency bands (eg, 1.83 GHz) used in each channel. In the mixed mode, legacy preambles (legacy STFs, legacy: CEs) are transmitted as duplicates through each channel. In an embodiment of the present invention, a new STF and a legacy ST can be simultaneously transmitted through a 400 MHz band between each channel. Gap filling of the CE field may be considered.

In this case, as shown in FIG. 9, the PPDU structure according to the present invention transmits ay STF, ay CE, ay header B, and payload in a broadband manner after legacy preamble, legacy header, and ay header A. Has a form. Therefore, the ay header, ay Payload field, and the like transmitted after the header field may be transmitted through channels used for bonding. Hereinafter, the ay header may be referred to as an enhanced directional multi-gigabit (EDMG) header to distinguish the ay header from the legacy header, and the name may be used interchangeably.

For example, a total of six or eight channels (each 2.16 GHz) may exist in 11ay, and a single STA may bond and transmit up to four channels. Thus, the ay header and ay Payload may be transmitted through 2.16 GHz, 4.32 GHz, 6.48 GHz, 8.64 GHz bandwidth.

Alternatively, the PPDU format when repeatedly transmitting the legacy preamble without performing the gap-filling as described above may also be considered.

In this case, ay STF, ay CE, and ay header B are replaced by a legacy preamble, legacy header, and ay header A without a GF-Filling and thus without the GF-STF and GF-CE fields shown by dotted lines in FIG. 8. It has a form of transmission.

10 is a diagram schematically illustrating a PPDU structure applicable to the present invention. Briefly summarizing the above-described PPDU format can be represented as shown in FIG.

As shown in FIG. 10, the PPDU format applicable to the 11ay system includes L-STF, L-CE, L-Header, EDMG-Header-A, EDMG-STF, EDMG-CEF, EDMG-Header-B, Data, It may include a TRN field, which may be selectively included according to the type of the PPDU (eg, SU PPDU, MU PPDU, etc.).

Here, a portion including the L-STF, L-CE, and L-header fields may be referred to as a non-EDMG portion, and the remaining portion may be referred to as an EDMG region. In addition, the L-STF, L-CE, L-Header, and EDMG-Header-A fields may be called pre-EDMG modulated fields, and the rest may be called EDMG modulated fields.

The (legacy) preamble portion of the PPDU includes packet detection, automatic gain control (AGC), frequency offset estimation, synchronization, modulation (SC or OFDM) indication, and channel measurement. (channel estimation) can be used. The format of the preamble may be common for the OFDM packet and the SC packet. In this case, the preamble may include a Short Training Field (STF) and a Channel Estimation (CE) field located after the STF field. (The preamble is the part of the PPDU that is used for packet detection, AGC, frequency offset estimation, synchronization, indication of modulation (SC or OFDM) and channel estimation.The format of the preamble is common to both OFDM packets and SC packets .The preamble is composed of two parts: the Short Training field and the Channel Estimation field.)

1.5. Low Density Parity Check (LDPC) Encoding

The LDPC encoding procedure consists of a plurality of steps: deciding the number of shortening / repetition bits in every codeword, shortening itself, Coding of each word, and repetition of bits.

A) First, the total number of data pad bits N _{DATA_PAD} using the number N _CW of LDPC _codework is calculated based on the following equation.

In the above equation, L _CW represents the length of the LDPC codeword, and the value may be set to 624 for the code rate R = 7/8 and to 672 for another code rate. Length indicates the length of PSDU (Physical Layer Convergence Procedure) Service Data Unit (PLCP) defined in the header field and may be defined in octet units. ρ has a value of 1 or 2 as a repetition factor, and R represents a code rate. N _CWmin is a value defined according to zero filling for a DMG (Directional Multi Gigabit) SC mode Beam Refinement Protocol (BRP) packet and may be defined as shown in the following table.

The scrambled PSDU is concatenated with N _{DATA_PAD} zeros. The configurations are scrambled using a continuation of the scrambler sequence that scrambled the PSDU input bits.

B) The procedure for converting the scrambled PSDU data into LDPC codewords is based on a repetition factor.

1) ρ is 1 and the code rate is not 7/8

i) The scrambler's output stream has the mth data word

sign

Broken into bit-sized blocks. Wherein the m value is less than or equal to N _CW .

ii) codeword

In each data word to generate

Parity bit

Is added.

2) If ρ is 1 and the code rate is 7/8, 48 bits are punctured from the parity bits of the rate 13/16 parity bits (48 bits are punctured from the parity bits of the rate 13/16 parity bits). .

i) The scrambler's output stream has the mth data word

Is broken into blocks of 546 bits. Wherein the m value is less than or equal to N _CW .

ii) codeword

126 parity bits in each data word to generate

Is added. The codeword

The first 48 parity bits

By removing from

Is generated as:

3) ρ is 2

i)

Is a sequence of 2L _Z length

Each codeword to produce

The data bits of

Concatenated with zeros.

ii) LDPC codeword

Parity bit

Is created by generating Here, H represents a parity matrix for rate 1/2 LDPC coding defined in 'Common LDPC Parity Matrices'.

iii) Sequence with XOR operation applied by PN (Pseudo Noise) sequence generated from Linear Feedback Shift Register (LFSR) used for data scrambling as defined in 'Scrambler'

Is replaced by L _Z +1 to 336 th bits of the codeword c. The LFSR is initialized with a vector of all values 1 and reinitialized to the same vector after every codewrod. Alternatively, the zero bits (e.g., L _Z +1 to 336 th bits of codeword c) are word repetition to which an XOR operation is applied by a PN sequence generated from LFSR used for MCS 1 scrambling. Replaced. In this case, the LFSR is initialized to an initial seed value (initial seed value) of all 1, and reinitialized to the same seed after every codeword.

C) the codewords are coded bits stream

Alternately (one after the other) to create a.

D) The number of symbol blocks N _BLKS and the number of symbol block padding bits N _{BLK_PAD} are calculated based on the following equation.

In the above equation, N _CBPB represents the number of coding bits per symbol block.

E) The coded bit stream is concatenated with N _{BLK_PAD} zeros. The configurations are scrambled by a continuation of the scrambler sequence that scrambled PSDU input bits.

1.6. LDPC encoding for SISO transmissions

For LDPC encoding for SISO transmission, the above-mentioned A)-C) of LDPC encoding are applied. In this case, it is assumed that L _CW is 624, 672, may be a _{1344-bit, L CW = 672, R =} 7/8 B.1 of LDPC encoding the above-described case of the code rate) encoding process may be used.

The number of SC symbol block N _BLSK and the number N of symbols _{BLK_PAD} block padding bit may be calculated based on the following equation.

In the above equation, N _CBPB represents the number of coding bits per block transmitted over the 2.16 GHz channel, and N _CB represents the number of consecutive 2.16 GHz channels that make up the signal bandwidth of the EDMG PPDU. At this time, N _CB may have a value of 1 to 4.

The values of N _CBPB for different types of GI (Guard Interval) are defined as shown in the following table. The coded bit stream is concatenated with N _{BLK_PAD} zeros. The configurations are scrambled by a continuation of the scrambler sequence that scrambled PSDU input bits.

1.7. LDPC encoding for MIMO transmissions

PSDU encoding procedure for MIMO transmission may be defined as follows.

The number of data pad bits N _{DATA_PAD} and the number of LDPC codewords per i th spatial stream N _CW i _SS may be calculated based on the following equation.

In the above equation, L _CW has a value of 672 or 1344 as an LDPC codeword length, and Length represents a length of a PSDU (Physical Layer Convergence Procedure) Service Data Unit (PLCP) defined (in octets) in a header field. ρ _i represents the repetition factor for the i-th spatial stream and R _i represents the code rate for the i-th spatial stream. N _{CBPS i} denotes the number of coded bits per symbol for the i-th spatial stream, and N _SS denotes the total number of spatial streams.

Bits distribution over the spatial streams

Bits distribution over the spatial streams is performed on the group basis with the number of bits in the group for i-th stream equal to

). The dispersion is performed in a round robin manner. That is, the first group of bits comes to the first stream and the second group of bits comes to the second stream. The procedure is repeated when it reaches the maximum number N of the _SS stream (The procedure is repeated when the maximum number of streams N _SS is reached).

The procedure of converting the scrambled PSDU data into an LDPC codeword is based on the above-described steps B) and C). B.1) Encoding procedure may be used for codes L _CW = 672 and R = 7/8.

The number of symbol blocks N _BLKS and the number of symbol block padding bits per i-th spatial stream N _{BLK_PAD iSS} are calculated based on the following equation.

In the above equation, N _SPB represents the number of symbols per block (or constellation points) transmitted over a 2.16 GHz channel. The value of N _SPB for different types of GI (Guard Interval) is defined as shown in the following table.

Coded bits for the i-th spatial stream are concatenated with N _{DATA_PAD iSS} zeros. The configurations are scrambled using a continuation of the scrambler sequence that scrambled the PSDU input bits. The padding bits of the first spatial stream are scrambled first, and the padding bits of the second spatial stream are scrambled second.

1.7. EDMG PHY entity

The EDMG STA may transmit and receive PPDUs that comply with mandatory PHY specifications.

For this purpose, the EDMG PHY is basically based on the DMG PHY. In addition, the EDMG PHY additionally supports space-time streams, downlink multi-user (MU) transmission, and multiple channel widths. The maximum number of spatial streams per STA is eight. MU PPDU transmission supports up to 8 STAs. For 2.16 + 2.16 GHz or 4.32 + 4.32 GHz transmissions, the maximum number of spatial streams in each channel is four.

EDMG STA supports the following features.

EDMG format (transmit and receive)

2.16 GHz and 4.32 GHz consecutive channel widths

-Single spatial stream (send and receive) within all supported channel widths

Non-EDMG duplicate formation transmission

In addition, the EDMG STA may support the following features.

2 or more spatial streams (transmit and receive) using SC modulation or OFDM modulation

EDMG MU PPDUs (transmit and receive) using SC modulation or OFDM modulation

-2.16 + 2.16 GHz channel width

4.32 + 4.32 GHz channel width

6.48 GHz channel width

8.64 GHz channel width

A 64-point non-uniform constellation

Channel-wise DL FDMA. That is, the EDMG PCP or EDMG AP may simultaneously transmit (signal) to multiple EDMG STAs to which different channels are assigned.

2. 본 발명에 적용 가능한 실시예2. Examples applicable to the present invention

As described above, the 802.11ay system to which the present invention is applicable supports DL FDMA on a channel basis and supports a combined channel 2.16 + 2.16 GHz or 4.32 + 4.32 GHz. Accordingly, the EDMG PCP / AP may perform channel unit DL MU FDMA in a channel aggregation situation.

Thus, the present invention will be described in detail a method for transmitting a signal transmitted for each user when the PCP / AP, DL MU FDMA transmission in SC mode in the 2.16 + 2.16 GHz or 4.32 + 4.32 GHz channel combination. More specifically, in the following description, a signal transmission method including LDPC encoding of data bits to be transmitted by the PCP / AP for each user (or STA) and SC symbol block padding method after LDPC encoding will be described in detail.

Hereinafter, the described configuration can be equally applied to the MU-MIMO situation.

In the 802.11ay system to which the present invention is applicable, up to two users can be allocated as the channel-based DL FMDA is supported. Thus, in case of 2.16 GHz + 2.16 GHz channelization, each user occupies a 2.16 GHz channel, and in case of 4.32 GHz + 4.32 GHz channelization, each user may occupy a 4.32 GHz channel. In this case, the PCP / AP may transmit signals through up to four spatial streams for each user (or for each channel).

2.1. If each user is a MIMO transmission

In this case, each parameter may be defined as follows.

L _{CW_u} : Indicates the length of the LDPC codeword of each user and may have one of 624,672, 1248, and 1344.

N _u : represents the number of users and can have a value of 1 or 2.

u: Represents a user index and may have a value of 1 or 2 as an example.

N _{ss, u} : _Represents the number of spatial streams in each user (each channel) and may have a value of 1 to 4.

N _{CW iss, u} : Codeword number of i th spatial stream of u th user

Length _u : Length of PSDU of uth user defined in header field (in octet)

ρρ _{iss, u} : Represents a repetition factor of the i-th spatial stream of the u-th user and may have a value of 1 or 2.

R _{iss, u} : represents the code rate of the i-th spatial stream of the u-th user, and may have one of 1/2, 5/8, 3/4, 13/16, and 7/8.

N _{CBPS iss, u} : _Represents the number of coded bits per symbol (constellation point) of the i-th spatial stream of the u-th user, and may have one of 1, 2, 4, and 6.

N _{CB, u} : represents the channel bonding factor (or the number of 2.16 GHz channels) of each user. For example, N _{CB, u} = 1 for 2.16 GHz + 2.16 GHz, and N _{CB, u} = 2 for 4.32 GHz + 4.32 GHz.

N _{BLKS, u} : Number of SC symbol blocks by user

N _SPB : Indicates the number of symbols per block (constellation point), the value may be different according to the GI. For example, N _SPB = 480 for Short GI, N _SPB = 448 for Normal GI, and N _SPB = 384 for Long GI.

In this case, padding may be performed on data of each user for LDPC encoding. This is because, in order to perform LDPC encoding, data of each user must be adjusted in units of LDPC code word length.

In the following description, N _{DATA_PAD, u} indicates the number of bits to be padded additionally when LDPC encoding is applied to the u-th user. In other words, N _{DATA_PAD, u} represents the number of padding bits needed to apply LDPC encoding to data of the u th user.

In this case, the padding bit of the first user User 1 and the number of codewords of each stream may be calculated based on the following equation.

Similarly, the padding bits of the second user (User 2) and the number of codewords of each stream may be calculated based on the following equation.

In this case, the PCP / AP may distribute bits into spatial streams for each user. In this case, the bit dispersion may be performed in group units.

The number of group bits of the i th stream of the u th user is

to be. Bit distribution in group units may be performed in a round robin manner. That is, the first group may be allocated to the first stream, the second group may be allocated to the second stream, and the second group may be allocated to the second stream.

Thus, for the first user (user 1)

Bit dispersion is applied to the spatial stream on a group basis, and for the second user (user 2)

Bit distribution to the spatial stream on a group basis may be applied.

Subsequently, the PCP / AP may perform LDPC encoding after bit parsing (or bit distribution) for each stream.

Subsequently, the PCP / AP may perform SC block padding according to an integer multiple of SC symbol blocks for each stream after LDPC coding. In this case, the block padding may be applied based on a user with a large number of SC symbol blocks among users.

In this case, the number of SC symbol blocks for each user may be calculated based on the following equation.

In this case, the number of largest SC symbol blocks for each user may be expressed as in the following equation.

Accordingly, the number of bits N _{BLK_PAD, iss, u to} be padded for each stream of each user may be calculated based on the following equation.

2.2. If each user is an SISO transfer

In this case, the LDPC encoding procedure for each user is 1.5. The LDPC encoding procedure described above in the section may be followed (step A)-step C)).

In this case, L _{CW u} represents the length of the LDPC codeword of each user, and may have one of 624, 672, 248, and 1344. In particular, when L _CW = 672, R = 7/8, 1.5. You can follow the procedure B.1) of the LDPC encoding described above in the section.

Through the above process, the PCP / AP _obtains N _{DATA_PAD, 1} and N _{CW, 1} for the first user (user 1), and N _{DATA_PAD, 2} and N _{CW, 2} for the second user (user 2). Can be obtained.

In this case, N _{CBPB, u} : represents the number of coded bits per block transmitted over the 2.16 GHz channel of each user.

Each symbol mapping, N _{CBPB, u} value for each GI may be defined as shown in the following table.

Subsequently, the PCP / AP may perform SC block padding according to an integer multiple of the number of SC symbol blocks after LDPC coding. In this case, the block padding may be performed based on a user having the largest number of SC symbol blocks among users.

Accordingly, the number of bits N _{BLK_PAD, u} to be padded per stream of each user may be calculated based on the following equation.

In the case of MU-MIMO, padding and block padding for each user may be performed in the same manner as described above.

In particular, in the case of MU-MIMO,

_Assume that N _u represents the number of users and can have a value from 1 to 8, and N _{ss, u} represents the number of spatial streams in each user (each channel) and can have a value from 1 to 4,

The remaining parameters can be equally applied.

First, the PCP / AP determines the maximum number of SC symbol blocks among the number of single carrier symbol blocks for low density parity check (LDPC) coded bits for each user (S1110). In step S1110, the PCP / AP may calculate the number of SC symbol blocks for each user based on Equation 13, and determine the number of double maximum SC symbol blocks based on Equation 14.

Subsequently, the PCP / AP determines the number of symbol block padding bits for each user based on the maximum number of SC symbol blocks (S1120). In step S1120, the PCP / AP may determine the number of symbol block padding bits for each user based on Equation 15.

Subsequently, the PCP / AP transmits a plurality of signals by concatenating a symbol block padding bit (or pad bit) for each user determined based on the maximum number of SC symbol blocks and an LDPC coded bit for each user. Transmit to the second STAs (S1130).

Here, the number of SC symbol blocks for each user includes the length of LDPC codewords for each user, the total number of lDPC codewords for each user, the number of consecutive 2.16 GHz channels through which the signal is transmitted, and the number of symbols per SC symbol block. And the number of coded bits per symbol for all spatial streams for each user. More specifically, the PCP / AP may determine the number of SC symbol blocks for each user based on Equation 10.

More specifically, the PCP / AP may generate LDPC coded bits for each user by concatenating (data) padding bits to data bits for each user in order to fit the LDPC codeword length unit, and performing LDPC encoding on them. have.

Such a signal may be transmitted through a channel aggregation 2.16 GHz + 2.16 GHz channel or 4.32 GHz + 4.32 GHz channel.

3. 장치 구성3. Device Configuration

The wireless device 100 of FIG. 12 may correspond to an STA for transmitting the signal described in the above description, and the wireless device 150 may correspond to an STA for receiving the signal described in the above description.

In this case, the station transmitting the signal may correspond to an 11ay terminal or PCP / AP supporting the 11ay system, and the station receiving the signal may correspond to an 11ay terminal or PCP / AP supporting the 11ay system.

Hereinafter, for convenience of description, an STA that transmits a signal is called a transmitting device 100, and an STA that receives a signal is called a receiving device 150.

The transmitter 100 may include a processor 110, a memory 120, and a transceiver 130, and the receiver device 150 may include a processor 160, a memory 170, and a transceiver 180. can do. The

transceiver

130 and 180 may transmit / receive a radio signal and may be executed in a physical layer such as IEEE 802.11 / 3GPP. The

processors

110 and 160 are executed in the physical layer and / or the MAC layer and are connected to the

transceivers

130 and 180.

The

processors

110 and 160 and / or the

transceivers

130 and 180 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. The

memory

120, 170 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage unit. When an embodiment is executed by software, the method described above can be executed as a module (eg, process, function) that performs the functions described above. The module may be stored in the

memories

120 and 170 and may be executed by the

processors

110 and 160. The

memories

120 and 170 may be disposed inside or outside the

processes

110 and 160, and may be connected to the

processes

110 and 160 by well-known means.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will understand that the present invention can be variously modified and changed from the above description. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

As described above, the present invention has been described assuming that it is applied to an IEEE 802.11-based WLAN system, but the present invention is not limited thereto. The present invention can be applied in the same manner to various wireless systems capable of data transmission based on channel bonding.

Claims

A method for transmitting a multi-user (MU) to a plurality of second STAs by a first station (STA) in a WLAN system,

Determining a maximum number of SC symbol blocks among the number of Single Carrier (SC) symbol blocks for Low Density Parity Check (LDPC) coded bits for each user; And

And transmitting to the plurality of second STAs a signal in which a pad bit for each user and an LDPC coded bit for each user are determined based on the maximum number of SC symbol blocks. , Multi-user transmission method.
The method of claim 1,

The number of SC symbol blocks for each user is

LDPC codeword length for each user, total number of lDPC codewords for each user, number of contiguous 2.16 GHz channels through which the signal is transmitted, number of symbols per SC symbol block, and symbol coding for all spatial streams for each user And is determined based on the number of bits that have been counted.
The method of claim 1,

LDPC coded bits for each user,

The data pad bit for each user and the data bit for each user are determined based on the total number of LDPC codes with each user.
The method of claim 1,

The first STA corresponds to a personal basic service set central point / access point (PCP / AP).
The method of claim 1,

The signal is transmitted through a channel aggregation 2.16 GHz + 2.16 GHz channel or 4.32 GHz + 4.32 GHz channel.
In the station apparatus for transmitting a signal in a WLAN system,

A transceiver having one or more RF (Radio Frequency) chains and configured to transmit and receive signals with a plurality of other station devices; And

A processor connected to the transceiver, the processor processing a signal transmitted / received with the plurality of other station devices,

The processor,

Determining a maximum number of SC symbol blocks among the number of Single Carrier (SC) symbol blocks for Low Density Parity Check (LDPC) coded bits for each user; And

And transmit a signal concatenated with each user pad bit and each user LDPC coded bit determined based on the maximum number of SC symbol blocks to the plurality of other station devices. Station devices.
The method of claim 6,

The number of SC symbol blocks for each user is

LDPC codeword length for each user, total number of lDPC codewords for each user, number of contiguous 2.16 GHz channels through which the signal is transmitted, number of symbols per SC symbol block, and symbol coding for all spatial streams for each user The station apparatus is determined based on the number of bits that have been counted.
The method of claim 6,

LDPC coded bits for each user,

The station apparatus is generated by concatenating the data pad bits for each user and the data bits for each user determined based on the total number of LDPC codes with each user.
The method of claim 6,

The station apparatus corresponding to a personal basic service set central point / access point (PCP / AP).
The method of claim 6,

Wherein the signal is transmitted over a channel aggregated 2.16 GHz + 2.16 GHz channel or a 4.32 GHz + 4.32 GHz channel.