KR101084127B1 - Automatic Retransmission Request Supporting Method in ODDMA Wireless Access System - Google Patents

Abstract

According to the present invention, when a multi-antenna system is used in an OFDMA radio access system supporting a hybrid auto retransmission reQest (HARQ) scheme, a signal is transmitted by multiple antennas through the same uplink or downlink data burst. The present invention relates to an automatic retransmission request support method in an OFDMA wireless access system that can reduce overhead caused by retransmission even when there is no transmission error. An automatic retransmission request support method in an OFDMA radio access system according to the present invention is a data burst to which a multi-antenna system is applied in an orthogonal frequency division multiplexing access (OFDMA) radio access system supporting a hybrid auto retransmission request (HARQ) scheme. allocating a transmission channel of an ACK / NACK signal for the data burst by the number of layers allocated to the data burst; And checking a transmission error of data received for each layer allocated to the data burst on a receiver side, and transmitting an ACK or NACK signal through a transmission channel of the allocated ACK / NACK signal.

OFDMA, data burst, HARQ, layer, overhead

Description

Method for supporting automatic retransmission request in OPDMA radio access system {Method of supporting HARQ in OFDMA radio access system}

1A to 1C are diagrams for explaining characteristics according to types of ARQ schemes.

2 to 5 are diagrams for explaining the characteristics according to the type of HARQ scheme.

6 shows a conceptual configuration of an OFDM scheme demodulator.

7 shows the configuration of a data frame in a conventional OFDMA wireless communication system.

8 shows the configuration of a data frame for allocating HARQ bursts in the prior art.

9 is a diagram for explaining a method of allocating an HARQ signal zone in a HARQ MAP message in the prior art.

10 is a view for explaining the encoding method for each layer in the prior art.

11 illustrates an example of a data frame in an OFDMA radio access system according to a preferred embodiment of the present invention.

12 is an exemplary diagram illustrating an allocation sequence of an ACK / NACK transport channel according to a preferred embodiment of the present invention.

FIG. 13 shows an example of a scheme of allocating the ACK / NACK transmission channel in an uplink ACK signal zone and a downlink ACK signal zone in another preferred embodiment of the present invention.

FIG. 14 illustrates an example of a scheme of allocating the ACK / NACK transmission channel in an uplink ACK signal zone and a downlink ACK signal zone according to another preferred embodiment of the present invention.

FIG. 15 shows an example of a method of allocating the ACK / NACK transmission channel in an uplink ACK signal zone and a downlink ACK signal zone by mixing a conventional scheme and a scheme according to the present invention in another preferred embodiment of the present invention. It is shown.

The present invention relates to an OFDMA radio access system. More specifically, the present invention provides a signal by multiple antennas through the same uplink or downlink data burst when a multiple antenna system is used in an OFDMA radio access system that supports a hybrid auto retransmission reQest (HARQ) scheme. The present invention relates to a method for supporting automatic retransmission request in an OFDMA radio access system that can reduce overhead caused by retransmission even when there is no transmission error in transmission.

The ARQ (Automatic Repeat Request) is a response message indicating whether the receiver correctly received the data after receiving the data transmitted from the transmitter in the communication system. There are three types of ARQ schemes as shown in FIGS. 1A to 1C.

FIG. 1A illustrates a 'stop-and-wait' ARQ scheme in which a receiver waits for an ACK or NACK message after transmitting data and then sends new data or retransmits. FIG. 1B is a 'go-back-N' ARQ scheme in which a transmitter continuously transmits data regardless of a response from a receiver, and retransmits it sequentially after receiving a NACK signal, and selects the 'Selective' shown in FIG. -repeat 'ARQ keeps sending data as well, and retransmits only the data that received the NACK signal.

HARQ (Hybrid ARQ) requires a higher data rate (2 Mbps, 10 Mbps or more) in a packet transmission communication system, and has a higher coding rate and a higher order modulation method (Rc = 5/6). , 3/4, Mod = 16-QAM, 64-QAM). As a larger error occurs on the channel, this technique is proposed as a way to solve this problem.

The ARQ method discards the data in which an error occurs during transmission, but the HARQ method applies FEC (Forward Error Correction) by storing the error data in a buffer and combining it with retransmitted information. That is, the HARQ method may be regarded as a method of combining FEC and ARQ. HARQ can be classified into four types as follows.

The first method is a Type I HARQ method as shown in FIG. 2, where data always detects forward error correction (FEC) in addition to an error detection code. If an error still exists in the packet, request retransmission. The erroneous packet is discarded and the retransmitted packet is used with the same FEC code.

The second Type II HARQ scheme shown in FIG. 3 is called an IR ARQ (Incremental Redundancy ARQ), and combines redundancy bits that are stored in a buffer without being discarded in error and retransmitted. When retransmitting, only the parity bits except the data bits are retransmitted. The parity bit to be retransmitted is different for every retransmission.

The third Type III HARQ scheme is a special case of Type II as shown in FIG. Each packet is self-decodable. Retransmission consists of a packet containing both an error part and data and is retransmitted. This method allows more accurate decoding than Type II, but is disadvantageous in terms of coding gain.

Finally, as shown in FIG. 5, the 'Type I with soft combining' method is a type I function, in which a function of storing data first transmitted from a receiving side and combining the retransmitted data with a metric is added. Also called metric combining or chase combining. This scheme is advantageous in terms of SINR, and the parity bits of retransmitted data always use the same one.

Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiplexing Access (OFDMA) is an active method for high-speed data transmission in wired and wireless channels. In the OFDM method, since a plurality of carriers having mutual orthogonality are used, frequency utilization efficiency is increased, and a process of modulating and demodulating the plurality of carriers at the transceiver stage is performed by performing an Inverse Discrete Fourier Transform (IDFT) and a Discrete Fourier Transform (DFT), respectively. The same result can be achieved at high speed using Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT).

The principle of OFDM divides a high speed data stream into a plurality of low speed data streams and transmits them simultaneously using a plurality of subcarriers, thereby increasing symbol duration to multi-path delay spread. It is to reduce relative dispersion in the time domain. Transmission of data by the OFDM scheme is based on transmission symbols.

Modulation and demodulation in the OFDM scheme can be processed collectively for all subcarriers using a Discrete Fourier Transform (DFT), so it is not necessary to design a demodulator for each individual subcarrier.

6 shows a conceptual configuration of an OFDM modulator. As shown in Fig. 6, the serially input data streams are converted into parallel data streams as many as subcarriers, and each parallel data stream is inverse discrete Fourier transform. Inverse Fast Fourier Transform (IFFT) is used for high speed data processing. The inverse discrete Fourier transformed data is converted back into serial data and transmitted through frequency conversion, and the receiving side receives the signal and demodulates the reverse process.                         

Resources in mobile communication systems are frequency channels, that is, frequency bands, and the methodology for efficiently allocating and using finite frequency bands among users is multiple access, and UL (downlink) and DL (downlink) in bidirectional communication. The linking methodology that distinguishes links is called multiplexing. Wireless multiple access and multiplexing is a platform technology that is the most basic technology of wireless transmission technology for efficiently using limited frequency resources, and is determined according to allocated frequency band, number of users, transmission rate, mobility, cell structure, and wireless environment.

Orthogonal Frequency Division Multiplexing (OFDM) is a type of multicarrier transmission / modulation (MCM) scheme that uses multiple carriers, in which input data is parallelized by the number of carriers and data is transmitted on each carrier. to be. OFDM has emerged as a candidate for a powerful radio transmission technology that satisfies the requirements of 4G mobile communication, and can be divided into OFDM-FDMA, OFDM-TDMA, and OFDM-CDMA according to a user's multiple access scheme. Each method has its advantages and disadvantages, and there are techniques to make up for the disadvantages.

Of these, OFDM-FDMA (OFDMA) is suitable for 4G macro / micro cellular infrastructure, with no intra-cell interference, high frequency reuse efficiency, and excellent adaptive modulation and granularity. In addition, in order to make up for the shortcomings of OFDM-FDMA, a diversity frequency hopping technique, a multiple antenna technique, and a strong encoding technique can be used to increase diversity and reduce the influence of inter-cell interference. The OFDMA method can efficiently allocate resources by allocating the number of subcarriers differently according to the transmission rate required by each user, and there is no need to initialize using a preamble before receiving data for each user like OFDM-TDMA. This increases transmission efficiency. In particular, the OFDMA method is suitable for a large number of subcarriers (that is, a large FFT size), and thus is effectively applied to a wireless communication system having a large area cell with a relatively large time delay spread. . In addition, the frequency-hopping OFDMA method overcomes the case where subcarriers are left in deep fading in a wireless channel or subcarrier interference by other users, thereby improving frequency diversity effect and improving interference average effect. Used to get FIG. 6 illustrates an OFDMA scheme in which a grid allocated in the frequency domain is frequency-hopped according to time slots.

7 shows the configuration of a data frame in a conventional OFDMA wireless communication system. In FIG. 7, the horizontal axis represents the time axis in symbol units, and the vertical axis represents the frequency axis in subchannel units. The subchannel means a bundle of a plurality of subcarriers. Specifically, in the OFDMA physical layer, active carriers are divided into groups and transmitted to different receivers for each group. The group of carriers transmitted to such a receiver is called a subchannel. In this case, carriers constituting each subchannel may be adjacent to each other or spaced at equal intervals.

The slot assigned to each user is defined by a data region in two-dimensional space, as shown in FIG. 7, which is a set of contiguous subchannels assigned by bursts. . In OFDMA, one data area is shown as a rectangle determined by time coordinates and subchannel coordinates, as shown in FIG. Such a data area may be allocated to an uplink of a specific user or a base station may transmit the data area to a specific user in downlink.

In the prior art of the OFDM / OFDMA wireless communication system, the base station allocates a data area to be transmitted through DL-MAP (DL-MAP) when there is data to be transmitted to the terminal. The UE receives data through the allocated area (DL bursts # 1 to # 5 in FIG. 7).

In FIG. 7, a downlink subframe starts with a preamble used for synchronization and equalization in a physical layer, and then a broadcast form for defining positions and uses of bursts allocated to downlink and uplink. The structure of the entire frame is defined through a DL MAP (DL-MAP) message and an UL MAP (UL-MAP) message.

The DL-MAP message defines the usage allocated per burst for the downlink interval in the burst mode physical layer, and the UL-MAP message defines the usage of the burst allocated for the uplink interval. Information element (IE) constituting DL-MAP is based on Downlink Interval Usage Code (DIUC), Connection ID (CID), and location information (subchannel offset, symbol offset, number of subchannels, number of symbols) of burst. Downlink traffic intervals are divided at the user end. On the other hand, the information elements constituting the UL-MAP message is determined by the Uplink Interval Usage Code (UIUC) for each CID (Connection ID), the location of the interval is defined by the 'duration'. Here, the use of each section is determined according to the UIUC value used in the UL-MAP, and each section starts at a point separated from the previous IE starting point by the 'duration' defined in the UL-MAP IE.

Downlink Channel Descriptor (DCD) messages and Uplink Channel Descriptor (UCD) messages are physical layer-related parameters to be applied in burst periods allocated to downlink and uplink, respectively, such as modulation type and FEC code type. It includes. In addition, it defines the necessary parameters (for example, K, R values of the R-S Code, etc.) according to various types of forward error correction codes. Such parameters are given by a burst profile defined for each Uplink Interval Usage Code (UIUC) and Downlink Interval Usage Code (DIUC) in UCD and DCD, respectively.

In the OFDMA communication system, the burst allocation scheme may be classified into a general MAP scheme and an HARQ scheme according to whether or not the HARQ scheme is supported.

In the downlink, a burst allocation scheme in a general MAP teaches a rectangular shape consisting of a time axis and a frequency axis, as shown in FIG. That is, it teaches the start symbol number (symbol offset), the start subchannel number (subchannel offset), the number of symbols used and the number of subchannels (No. OFDMA symbols, No. Subchannels) used. Uplink uses a method of assigning the symbol axis in sequence so that the burst of uplink can be allocated by only teaching the number of symbols used.

8 shows a data frame according to HARQ MAP. Unlike the general MAP, the HARQ MAP uses a scheme in which uplink and downlink are sequentially assigned to subchannel axes. HARQ MAP only tells the length of the burst. This method allocates bursts sequentially, as shown in FIG. The start position of the burst is the position where the previous burst ended and occupies radio resources by the length allocated from the start position. The method described below relates to a method of assigning bursts cumulatively along the frequency axis, and the method of assigning bursts along the time axis also follows the same principle.

In addition, in the HARQ MAP, the MAP message may be divided into several pieces (see FIG. 8: HARQ MAP # 1, # 2, ..., #N) so that each MAP message may have any burst information. For example, MAP message # 1 may include burst # 1, MAP message # 2 may include burst # 2, and MAP message # 3 may include information of bursts # 3 to # 5.

As described above, HARQ MAP is used to support HARQ in an OFDMA system. HARQ MAP has a HARQ MAP pointer IE in the DL MAP, and when the HARQ MAP location is known, the HARQ MAP uses a method of sequentially assigning bursts to downlink subchannel axes in the HARQ MAP. The start position of the burst is the position where the previous burst ended and occupies radio resources by the length allocated from the start position. The same applies to the uplink.

In addition to the HARQ MAP, control information should be informed. Table 1 shows the data format of the HARQ control IE for informing the control information.

Syntax Size (bits) Notes HARQ_Control_IE () {   Prefix One 0 = Temporary disable HARQ
1 = enable HARQ   If (Prefix == 1) {     AI_SN One HARQ ID Seq. No     SPID 2 Subpacket ID     ACID 4 HARQ CH ID   } else {      reserved 3 Shall be set to zero   } }

The control information includes AI_SN, SPID, SCID, etc., AI_SN is toggled to '0' and '1' when the burst is successfully transmitted on the same ARQ channel, and transmits the new burst or the previous burst. This value indicates whether to retransmit. Four types of redundancy bits are provided for each data bit included in each burst for HARQ transmission. The SPID is a value for selecting a different redundancy bit for each retransmission, and the SCID is an HARQ channel ID.

The ACK / NACK signal is indicated to the ACK signal region of the uplink whether the transmitted data burst has been successfully received. If the UE receives the burst in the i-th frame, the ACK / NACK signal is sent to the uplink ACK signal region of the (i + j) -th frame. The j value is sent by UCD. A method of allocating an ACK signal zone includes a method of allocating an ACK signal zone for each HARQ MAP message in uplink and a method in which two or more HARQ MAP messages use one ACK signal zone among multiple HARQ MAP messages in a frame. There is this.

A method of determining a HARQ ACK region of a frame as one and informing slots of an ACK / NACK signal of a burst indicated by a HARQ MAP message in order will be described in detail.

9 is a diagram for explaining a method of allocating an HARQ signal zone in a HARQ MAP message. ACK to allocate ACK signal zone in HARQ MAP message Four pieces of information (OFDMA Symbol offset, Subchannel offset, No. OFDMA Symbols, No. Subchannels) of a signal zone are allocated to the uplink. Each terminal sequentially inputs an ACK / NACK signal of whether each burst has been successfully received into an ACK signal region (Fig. 9) allocated to uplink. The start position of the ACK / NACK signal is the next position of the previously received ACK / NACK information. The order of the ACK.NACK signal follows the downlink burst order in the HARQ MAP message. That is, ACK / NACK signals in the uplink HARQ ACK region which are already allocated in the order of bursts # 1, # 2, # 3, and # 4 are also assigned to bursts as # 1, # 2, # 3, and # 4. Will be sent in the corresponding order.

As shown in FIG. 9, MAP Message # 1 contains allocation information of bursts # 1 and # 2, MAP Message # 2 contains allocation information for bursts # 3 and # 4, and MAP Message # 3 contains Contains allocation information for bursts # 5, # 6, and # 7. MSS # 1 looks at the information of burst # 1 in the contents of MAP Message # 1 and informs the first slot in the ACK signal region indicated in the HARQ MAP message whether the transmitted data was successfully received. MSS # 2 notifies the next sequence of ACK / NACK signal slots of burst # 1 within the ACK signal region. MSS # 3 calculates the sum of the bursts # 1 and # 2 of MAP Message # 1 to know the location in the HARQ ACK region. In this way, the positions of all HARQ ACK zones can be known sequentially.

In this case, when one UE supports multiple antennas in the downlink burst region and sends data in the same region, or when multiple UEs transmit data in the same region, the CRC does not generate an error for all layers. Only send ACK signal, otherwise NACK signal. Here, the layer refers to a unit of coding of transmitted data, and may have a number from 1 to as many antennas. For example, after coding all the transmitted data and inserting CRC and dividing it by the number of antennas and transmitting through all antennas, the number of layers is one, and the data carried on each antenna is coded and CRC is inserted. When transmitting, the number of layers is equal to the number of antennas (see FIG. 10). The above situation also applies when the terminal transmits the burst in uplink and the base station receives the burst and sends down the ACK signal in the downlink.

In the prior art as described above, the present invention can be simply applied to a non-multi-antenna system. However, in the case of the multi-antenna system, a waste of resources occurs when the conventional technology is used. For example, if two terminals have their own data in burst # 2 (the number of layers is 2), the base station detects that the burst of terminal # 1 did not generate an error, but the burst of terminal # 2 In case of an error, a NACK signal is transmitted to both terminals according to the above-described principles of the prior art. Then both terminals must send data again. As a result, even though the data of the terminal # 1 has been transmitted without error, a waste of resources occurs because it has to be discarded and retransmitted. In the case of downlink, the above-described problem in uplink may be applied as it is.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to transmit when a signal transmission by a plurality of antennas through the same uplink or downlink data burst in a multi-antenna system The present invention provides a method for supporting automatic retransmission request in an OFDMA broadband wireless access system that can reduce overhead caused by retransmission even when there is no error.

Summary of the Invention

The present invention discloses a method for transmitting an ACK or NACK signal for each layer in the case of an uplink or downlink data burst to which the multi-antenna system is applied to solve the above technical problem. . In other words, for uplink or downlink data bursts to which the multi-antenna system is applied, as many ACK / NACK signal transmission channels as the number of layers allocated to the data burst are allocated.

When one terminal supports multiple antennas in the downlink burst region to send data in the same region or when multiple terminals transmit data in the same region, signals of all layers are displayed in the same region but are detected by the receiving side. The signal per layer can be distinguished. The CRC may be checked with respect to the signal of each distinguished layer to determine whether the signal of each layer is in error. The present invention is to transmit a ACK or NACK signal to determine whether the error of each signal known in each layer so that the sender can know each. In order to support this, an allocation of an ACK or NACK channel for each layer is required in order to be able to convey an error of a signal for each layer. The side that transmits the burst through the channels can receive an ACK or NACK signal for each layer, and determine the next transmission method according to the signal. That is, the signal of the NACK layer is retransmitted, and the signal of the ACK layer stops transmitting until other layers receive the ACK signal according to the implementation method of the system to reduce interference with other signals, or waits. You can increase the amount of data by loading other data. As such, in order to use a different transmission method for each layer, control information should be provided for each layer. That is, conventionally, since all layers received ACK or NACK together, control information could be bundled together to give control information. According to the method of the present invention, whether to give a new burst or retransmit the previous burst according to whether each layer receives ACK or NACK. (AI_SN), how many redundancy bits to give (SPID) and the H-ARQ channel ID (SCID) should be determined.

An automatic retransmission request support method in an OFDMA radio access system according to the present invention is a data burst to which a multi-antenna system is applied in an orthogonal frequency division multiplexing access (OFDMA) radio access system supporting a hybrid auto retransmission request (HARQ) scheme. allocating a transmission channel of an ACK / NACK signal for the data burst by the number of layers allocated to the data burst; And checking a transmission error of data received for each layer allocated to the data burst on a receiver side, and transmitting an ACK or NACK signal through a transmission channel of the allocated ACK / NACK signal.

Example

The construction, operation and other features of the present invention will be readily understood by the preferred embodiments of the present invention described below with reference to the accompanying drawings.

FIG. 11 illustrates an example of a data frame in an OFDMA radio access system according to an embodiment of the present invention, and is applied to a base station transmitting data to a plurality of terminals by two layers by applying a multi-antenna system. Is a diagram for explaining an embodiment of a method for allocating an ACK / NACK transmission channel.

In FIG. 11, a base station allocates a DL ACK SIGNAL REGION to a DL subframe and an UL ACK SIGNAL REGION to an UL subframe. Allocate The downlink ACK signal zone is a zone allocated for an ACK or NACK signal transmitted by the base station in response to data transmitted by a plurality of terminals. The uplink ACK signal zone is a zone allocated for an ACK or NACK signal transmitted by the plurality of terminals as a response to data transmitted by the base station.

When the base station transmits data bursts by two layers, the terminals receiving data bursts by the two layers check a transmission error of data transmitted for each layer of the base station (for example, According to the result, if there is no transmission error for each layer, an ACK signal is transmitted, and if there is a transmission error, an NACK signal is transmitted. One ACK / NACK transmission channel is allocated to terminals receiving a data burst transmitted by the base station to one layer. As a result, the number of ACK / NACK transmission channels (#) equal to the number of layers used by the base station to transmit each data burst in the uplink ACK signal region of an uplink subframe for each user equipment (# 1-1, # 1-2, # 2-1, # 2-2, # 3, # 4, ....).

The base station allocates an ACK / NACK transmission channel (# 2-1, # 2-2) for each terminal for data transmission by two layers in the downlink ACK signal region, and assigns one layer. One ACK / NACK transmission channel (# 1, # 3, # 4, ...) is allocated to the UEs. The base station checks a transmission error for data transmitted from the terminal (for example, CRC check), and transmits an ACK signal if there is no transmission error for each layer according to the result, and transmits a NACK signal if there is a transmission error. do.

The ACK / NACK transmission channel may be allocated in the order of time in the uplink ACK signal region and the downlink ACK signal region in order, may be allocated in the order of frequency axis, or may be allocated alternately in the frequency axis and time axis. . Conventionally, half subchannels are used for one ACK or NACK signal and assigned in alternating frequency and time axes, that is, in the order shown in FIG. The half subchannel consists of 24 subcarriers.

13 is an example of another scheme of allocating the ACK / NACK transmission channel in an uplink ACK signal zone and a downlink ACK signal zone. FIG. 13 illustrates an example of separately allocating an uplink or downlink ACK zone for a UE to which a multi-antenna system is applied in an uplink ACK signal zone and a downlink ACK signal zone. That is, for a terminal transmitting data bursts by two layers in a downlink ACK region, the ACK / NACK transmission channel (# 2-1) for the first layer is bursted by one layer. ACK / NACK transmission channel for the terminal for transmitting the same as the ACK / NACK transmission channel for the second layer for the terminal transmitting data burst by the two layers (2-layer) (# 2-2) ) Is a method of allocating a separate ACK region within the downlink ACK region. The same scheme is applied to the UL ACK region. In FIG. 13, the base station transmits HARQ DL burst # 2 by four layers. The separate ACK zone allocated for the second or more layers is preferably allocated after the zone in which the ACK / NACK transport channel for the first layer is allocated.

14 is an example of another scheme of allocating the ACK / NACK transmission channel in an uplink ACK signal zone and a downlink ACK signal zone. FIG. 14 is the same as in the example of FIG. 13 but separately assigns an uplink or a downlink ACK zone for a UE to which a multi-antenna system is applied in the uplink ACK signal zone and the downlink ACK signal zone. An example of allocating a plurality of ACK / NACK transmission channels # 2-2, # 2-3, and # 2-4 for the same data burst to one ACK / NACK transmission channel using a codeword. That is, in the example of FIG. 13, since the range of the uplink ACK region can be unnecessarily enlarged as the number of layers increases, the codeword is used to reduce the range using the codeword.

Tables 2 and 3 illustrate codewords for supporting FIG.

Codeword [Layer 4 Layer 3 Layer 2] Group sets (total 24 subcarriers) C0 [0 0 0] G0 G0 G0 C1 [0 0 1] G4 G7 G2 C2 [0 1 0] G7 G2 G4 C3 [0 1 1] G2 G4 G7 C4 [1 0 0] G1 G3 G5 C5 [1 0 1] G3 G5 G1 C6 [1 1 0] G5 G1 G3 C7 [1 1 1] G6 G6 G6

Group set 8 subcarrier signals to transmit G0 P0, P1, P2, P3, P0, P1, P2, P3 G1 P0, P3, P2, P1, P0, P3, P2, P1 G2 P0, P0, P1, P1, P2, P2, P3, P3 G3 P0, P0, P3, P3, P2, P2, P1, P1 G4 P0, P0, P0, P0, P0, P0, P0, P0 G5 P0, P2, P0, P2, P0, P2, P0, P2 G6 P0, P2, P0, P2, P2, P0, P2, P0 G7 P0, P2, P2, P0, P2, P0, P0, P2

In the transmission of an uplink ACK / NACK signal, as described above, a half subchannel consisting of 24 subcarriers per ACK or NACK signal is used, and codewords such as those shown in Tables 2 and 3 are used. Up to three ACK or NACK signals can be transmitted using 24 subcarriers. Examples of Tables 2 and 3 define codewords for four layers, and can be applied to two or three layers using them. In other words, for data bursts with three layers applied, ignore the layer 4 in Tables 2 and 3, and ignore the layers 4 and 3 for data bursts with the two layers applied. On the other hand, in the case of downlink, when transmitting an ACK / NACK signal using one bit as in the conventional method, the need for using a codeword is reduced.

15 is an example of a scheme of allocating the ACK / NACK transmission channel in an uplink ACK signal region and a downlink ACK signal region by mixing a conventional scheme and a scheme according to the present invention. That is, the ACK zone for the UE using the data burst to which the multi-antenna system is applied is separately allocated in the same manner as in FIG. 13 or FIG. The ACK / NACK transmission channel is allocated to transmit an ACK signal only when no signal is transmitted and to transmit a NACK signal when it is not.

Tables 4 and 5 show the formats of the MIMO compact DL-MAP IE and the MIMO compact UL-MAP IE, respectively, according to an embodiment of the present invention.                     

The conventional information element (IE) cannot support the present invention because control information per layer cannot be set aside. Therefore, whether to give a new burst or retransmit the previous burst depending on whether each layer receives an ACK or NACK in an information message (MIMO Compact DL / UL MAP IE) for supporting HARQ multiple antennas (AI_SN), 4 The number of redundancy bits of the type (SPID) and the control information according to the H-ARQ channel ID (SCID) should be given so that each layer can operate differently. The control information may have a field in an information message (MIMO Compact DL / UL MAP IE) for supporting HARQ multi-antenna directly as needed, and as shown in the embodiment, an information element called 'Control_IE' It can also be used to insert information messages (MIMO Compact DL / UL MAP IE) to support.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

According to the method for supporting automatic retransmission request in an OFDMA radio access system according to the present invention, in the multi-antenna system, an ACK or NACK signal is transmitted for each layer when a signal is transmitted by multiple antennas through the same uplink or downlink data burst. Since the transmission, even if there is no transmission error, the overhead caused by the retransmission must be reduced.

Claims (21)

In the method for transmitting packet data in a radio access system supporting multiple antennas (MIMO), Receiving at least one data burst comprising a plurality of data map information elements and a plurality of layer signals; And Transmitting a plurality of acknowledgment (ACK) statuses indicating whether each of the plurality of layer signals has been successfully decoded through an uplink ACK channel; Each of the plurality of layer signals is encoded in a corresponding channel encoder, and a first map information element of the plurality of data map information elements includes control information for each of the plurality of layer signals. The control information for each of the plurality of layer signals includes a HARQ channel identifier, a HARQ identifier sequence number, and a subpacket identifier. A second map information element of the plurality of data map information elements provides information on an area to which the uplink ACK channel is allocated. Each of the plurality of ACK states is allocated to an ACK channel of an uplink data frame associated with the plurality of ACK states, and is indicated through a half subchannel including 24 subcarriers. delete delete delete delete delete delete delete delete delete delete The method of claim 1, The region to which the uplink ACK channel is allocated is A first region allocated to an ACK state for a first layer of the plurality of layer signals; And And a second area allocated to each of the ACK states for at least one layer except the first layer among the plurality of layer signals. The method of claim 1, The region to which the uplink ACK channel is allocated is A first region allocated to an ACK state of a first layer signal of the plurality of layer signals; And And a second area allocated to a codeword indicating an ACK state of a layer signal except the first layer signal among the plurality of layer signals. The method of claim 13, And said 24 subcarriers comprise a combination of three modulation symbol groups, said three modulation symbol groups being selected from group sets G0 to G7 as shown in the following table. Group set 8 subcarrier signals to be transmitted G0 P0, P1, P2, P3, P0, P1, P2, P3 G1 P0, P3, P2, P1, P0, P3, P2, P1 G2 P0, P0, P1, P1, P2, P2, P3, P3 G3 P0, P0, P3, P3, P2, P2, P1, P1 G4 P0, P0, P0, P0, P0, P0, P0, P0 G5 P0, P2, P0, P2, P0, P2, P0, P2 G6 P0, P2, P0, P2, P2, P0, P2, P0 G7 P0, P2, P2, P0, P2, P0, P0, P2. The method of claim 1, And the channel encoder comprises a forward error encoder (FEC). The method of claim 1, The plurality of ACK states are first allocated on the frequency axis within the uplink ACK channel region and then on the time axis. An apparatus for transmitting packet data in a wireless access system supporting multiple antennas (MIMO), A receiving module for receiving at least one data burst including a plurality of data map information elements and a plurality of layer signals; And A transmission module for transmitting a plurality of acknowledgment (ACK) states indicating whether each of the plurality of layer signals has been successfully decoded through an uplink ACK channel; A first map information element of the plurality of data map information elements includes control information for each of the plurality of layer signals. The control information for each of the plurality of layer signals includes a HARQ channel identifier, a HARQ identifier sequence number, and a subpacket identifier. A second map information element of the plurality of data map information elements provides information on an area to which the uplink ACK channel is allocated. Each of the plurality of ACK states is allocated to an ACK channel of an uplink data frame associated with the plurality of ACK states, and is indicated through a half subchannel consisting of 24 subcarriers. The method of claim 17, The region to which the uplink ACK channel is allocated is A first region allocated to an ACK state for a first layer of the plurality of layer signals; And And a second area allocated to each of the ACK states of at least one layer except for the first layer among the plurality of layer signals. The method of claim 17, The region to which the uplink ACK channel is allocated is A first region allocated to an ACK state of a first layer signal of the plurality of layer signals; And And a second area allocated to a codeword indicating an ACK state of a layer signal except the first layer signal among the plurality of layer signals. The method of claim 19, And said 24 subcarriers comprise a combination of three modulation symbol groups, said three modulation symbol groups being selected from group sets G0 to G7 as shown in the following table. Group set 8 subcarrier signals to be transmitted G0 P0, P1, P2, P3, P0, P1, P2, P3 G1 P0, P3, P2, P1, P0, P3, P2, P1 G2 P0, P0, P1, P1, P2, P2, P3, P3 G3 P0, P0, P3, P3, P2, P2, P1, P1 G4 P0, P0, P0, P0, P0, P0, P0, P0 G5 P0, P2, P0, P2, P0, P2, P0, P2 G6 P0, P2, P0, P2, P2, P0, P2, P0 G7 P0, P2, P2, P0, P2, P0, P0, P2. The method of claim 17, The plurality of ACK states are first allocated on a frequency axis in the uplink ACK channel region and then on a time axis.

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