KR20100134024A

KR20100134024A - Method for performing a harq in a radio communication system

Info

Publication number: KR20100134024A
Application number: KR1020107022662A
Authority: KR
Inventors: 박형호
Original assignee: 엘지전자 주식회사
Priority date: 2008-06-16
Filing date: 2009-06-16
Publication date: 2010-12-22
Also published as: WO2009154394A3; KR101140091B1; WO2009154394A2

Abstract

PURPOSE: In the wireless telecommunications system, the HARQ implementing method reduces the control signal overhead for being proceed the HARQ process by reducing the waste of the resources allocated for HARQ. CONSTITUTION: The base station and terminal hold in common the HARQ timing(S100). The HARQ timing implies the ACK/NACK transmission time and/or data retransmission point of time. The base station transmits data with the terminal(S110). The terminal transmits the ACK/NACK with the base station(S120).

Description

How to perform HARQ in wireless communication system {METHOD FOR PERFORMING A HARQ IN A RADIO COMMUNICATION SYSTEM}

The present invention relates to wireless communication, and more particularly, to a method for performing a hybrid automatic repeat request (HARQ) in a wireless communication system.

Error compensation techniques for securing communication reliability include a forward error correction (FEC) scheme and an automatic repeat request (ARQ) scheme. In the FEC scheme, an error at the receiver is corrected by adding an extra error correction code to the information bits. In the ARQ scheme, errors are corrected through data retransmission, and there are a stop and wait (SAW), a go-back-N (GBN), and a selective repeat (SR) scheme. The SAW method is a method of transmitting the next frame after checking whether the transmitted frame is correctly received. The GBN method transmits N consecutive frames and retransmits all frames transmitted after the frame in which an error occurs if transmission is not successful. The SR method selectively retransmits only a frame in which an error occurs.

The FEC method has a short time delay and does not require information to be exchanged between the transmitter and the receiver, but has a disadvantage in that the system efficiency is poor in a good channel environment. ARQ method can improve the transmission reliability, but it has the disadvantage of incurring time delay and inferior system efficiency in poor channel environment. To solve these shortcomings, a hybrid automatic repeat request (HARQ) method combining FEC and ARQ is proposed. According to the HARQ method, whether the data received by the physical layer includes an error that cannot be decoded, and when an error occurs, retransmission is requested to improve performance.

The HARQ-type receiver basically attempts error correction on received data and determines whether to retransmit using an error detection code. The error detection code may use a cyclic redundancy check (CRC). When the CRC detection process detects an error in the received data, the receiver sends a non-acknowledgement (NACK) signal to the transmitter. The transmitter receiving the NACK signal transmits appropriate retransmission data according to the HARQ mode. The receiver receiving the retransmitted data improves the reception performance by combining and decoding the previous data and the retransmitted data.

The mode of HARQ may be classified into chase combining and incremental redundancy (IR). Chase combining is a method of obtaining a signal-to-noise ratio (SNR) gain by combining with retransmitted data without discarding the data where an error is detected. IR is a method in which additional redundant information is incrementally transmitted to retransmitted data, thereby reducing the burden of retransmission and obtaining a coding gain.

HARQ may be classified into adaptive HARQ and non-adaptive HARQ according to transmission attributes such as resource allocation, modulation technique, transport block size, and the like. Adaptive HARQ is a method in which transmission attributes used for retransmission are changed in whole or in part compared to initial transmission according to a change in channel conditions. Non-adaptive HARQ is a method of continuously using the transmission attribute used for the initial transmission regardless of the change in channel conditions.

HARQ may be classified into synchronous HARQ and asynchronous HARQ according to data retransmission timing. According to the synchronous HARQ, the base station and the terminal knows the data retransmission time point (implicit). According to the asynchronous HARQ, since resources are allocated at random times for data retransmission, separate signaling for data retransmission is required.

An acknowledgment / non-acknowledgement (ACK / NACK) transmission time and a data retransmission time point may vary according to a ratio of a downlink region and an uplink region in a frame and a processing delay of a terminal / base station. Therefore, it is necessary to set the ACK / NACK transmission time and data retransmission time according to each case.

The technical problem to be solved by the present invention is to provide a method of performing HARQ.

In a wireless communication system according to an aspect of the present invention, a method of performing HARQ of a terminal may include receiving data from a base station and performing ACK / NACK on the data at a point in time passed from the time point at which the data is transmitted from the base station. And transmitting to the base station, wherein information about the predetermined period of time is shared between the base station and the terminal.

The information on the predetermined period may include at least one of the predetermined period and information for determining the predetermined period.

The information for determining the predetermined period includes at least one of a ratio of an uplink region and a downlink region in a time division duplex (TDD) frame, a processing delay of the terminal, a processing delay of the base station, and a time point at which the data is transmitted from the base station. There may be at least one.

The method may further include receiving a control signal including information about the predetermined period from the base station.

The control signal may be transmitted through a super frame header.

The predetermined period according to the ratio of the uplink region and the downlink region in the TDD frame and the time point at which the data is transmitted may be as shown in the table below.

The predetermined period according to the ratio of the uplink region and the downlink region in the TDD frame and the time point at which the data is transmitted may be as shown in the following table.

In a wireless communication system according to an aspect of the present invention, a method for performing HARQ of a base station includes transmitting data to a terminal, receiving a non-acknowledgement (NACK) signal for the data transmission from the terminal, and transmitting the NACK signal. And retransmitting the data to the terminal at a time after a predetermined period of time has passed, wherein information about the predetermined period is shared between the base station and the terminal.

The predetermined period of time may be determined based on at least one of a ratio of an uplink region and a downlink region in a TDD frame, a processing delay of the terminal, a processing delay of the base station, and a time point at which the data is transmitted from the base station.

A terminal according to an aspect of the present invention includes a radio frequency (RF) unit and a processor connected to the RF unit, wherein the processor receives data from a base station, and a predetermined period from a time point at which the data is transmitted from the base station The ACK / NACK for the data is transmitted to the base station at the last time, and the information about the predetermined period is shared between the base station and the terminal.

An efficient method of performing HARQ may be provided. The waste of resources allocated for HARQ can be reduced. In addition, it is possible to reduce the control signal overhead for performing the HARQ process, it is possible to reduce the time delay (latency) according to the HARQ process.

1 shows a wireless communication system.
2 shows an example of a frame structure.
3 is an exemplary diagram illustrating processing of an information block for performing HARQ.
4 shows an example of a redundancy version of an encoded packet.
5 shows data transmission using HARQ.
6 is a flowchart illustrating a method of performing HARQ according to an embodiment of the present invention.
7 illustrates HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 4: 4.
8 and 9 illustrate HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 5: 3.
10 illustrates HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3.
11 shows HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3.
12 illustrates HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3.
13 and 14 illustrate HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 6: 2.
15 to 18 illustrate HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 6: 2.
19 shows HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 6: 2.
20 is a block diagram illustrating a transmitter and a receiver for transmitting and receiving data using a method of performing HARQ according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16e (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), or the like. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. IEEE 802.16m is an evolution from IEEE 802.16e.

For clarity, the following description focuses on IEEE 802.16m, but the technical spirit of the present invention is not limited thereto.

1 shows a wireless communication system.

Referring to FIG. 1, a wireless communication system includes at least one base station 20 (BS). Each base station 20 provides a communication service for a particular geographic area (generally called a cell). The cell may again be divided into multiple regions (referred to as sectors). The user equipment (UE) 10 may be fixed or mobile, and may include a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), It may be called other terms such as a wireless modem and a handheld device. The base station 20 generally refers to a fixed station communicating with the terminal 10, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point. have.

Hereinafter, downlink (DL) means communication from the base station to the terminal, and uplink (UL) means communication from the terminal to the base station. In downlink, a transmitter may be part of a base station and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal and a receiver may be part of a base station.

2 shows an example of a frame structure.

Referring to FIG. 2, a superframe includes a superframe header and four frames (frames, F0, F1, F2, and F3). The size of each superframe is 20ms and the size of each frame is illustrated as 5ms, but is not limited thereto. The superframe header (SFH) may be disposed in the first subframe of the superframe and a common control channel may be allocated. The common control channel is a channel used for transmitting control information that can be commonly used by all terminals in a cell, such as information on frames or system information of a superframe. SFH is multiplexed by A-MAP (Advanced MAP) and TDM (Time Division Multiplexing). SFH is divided into P-SFH (Primary SFH) and S-SFH (Secondary SFH). A-MAP carries unicast service control information. Unicast service control information includes user specific control information and non-user service control information. The user specific control information is divided into assignment information, HARQ feedback information, and power control information, which may be transmitted in the allocation A-MAP, the HARQ feedback A-MAP, and the power control A-MAP, respectively.

One frame includes eight subframes (Subframe, SF0, SF1, SF2, SF3, SF4, SF5, SF6, SF7). Each subframe may be used for uplink or downlink transmission. The subframe may consist of 6 or 7 OFDM symbols, but this is only an example. Some of the OFDM symbols constituting the subframe may be idle symbols. Time division duplexing (TDD) or frequency division duplexing (FDD) may be applied to the frame. In TDD, each subframe is used in uplink or downlink at different times at the same frequency. That is, subframes in the TDD frame are divided into an uplink subframe and a downlink subframe in the time domain. In FDD, each subframe is used in uplink or downlink on different frequencies at the same time. That is, subframes in the FDD frame are divided into an uplink subframe and a downlink subframe in the frequency domain. Uplink transmission and downlink transmission occupy different frequency bands and may be simultaneously performed.

The subframe includes at least one frequency partition. The frequency partition is composed of at least one Physical Resource Unit (PRU). The frequency partitions may include Localized PRUs and / or Distributed PRUs. Frequency partitioning may be used for other purposes such as Fractional Frequency Reuse (FFR) or Multicast and Broadcast Services (MBS).

A PRU is defined as a basic physical unit for resource allocation that includes a plurality of consecutive OFDM symbols and a plurality of consecutive subcarriers. The number of OFDM symbols included in the PRU may be equal to the number of OFDM symbols included in one subframe. For example, when one subframe consists of 6 OFDM symbols, the PRU may be defined with 18 subcarriers and 6 OFDM symbols. Logical Resource Units (LRUs) are basic logical units for distributed resource allocation and localized resource allocation. The LRU is defined by a plurality of OFDM symbols and a plurality of subcarriers and includes pilots used in a PRU. Thus, the appropriate number of subcarriers in one LRU depends on the number of pilots assigned.

Logical Distributed Resource Units (DRUs) may be used to obtain frequency diversity gain. The DRU includes subcarrier groups distributed in one frequency partition. The size of the DRU is equal to the size of the PRU. The smallest unit that forms a DRU is one subcarrier.

Logical Contiguous Resource Units (CRUs) may be used to obtain frequency selective scheduling gains. The CRU includes a local subcarrier group. The size of the CRU is equal to the size of the PRU.

3 is an exemplary diagram illustrating processing of an information block for performing HARQ.

Referring to FIG. 3, all or part of an information block is sent to a transport block for transmission to a physical layer, and one transport block is appended with a CRC, which is an error detection code. This is called a CRC attachment. The information block may be referred to as a Protocol Data Unit (PDU) of Medium Access Control (MAC). When a layer that performs HARQ is called a physical layer, a MAC PDU is a data unit transmitted from the upper layer MAC layer to the physical layer.

The transport block appended with the CRC is divided into appropriate sizes for channel encoding. This is called code block segmentation. The divided block is called a code block. An encoder performs channel encoding on a code block and outputs an encoded packet. The encoder can apply a turbo code, which is one of the error correction codes. The turbo code is a structural code that includes information bits as structural bits. In the case of turbo codes with a code rate of 1/3, two parity bits are allocated to one structural bit. However, the technical concept of the present invention can be applied to an LDPC (low density parity check code) or other convolutional codes as well as the error correction code.

One HARQ function is performed in units of transport blocks. The HARQ processor performs an HARQ mode (chase combined or IR) and an HARQ scheme (adaptive HARQ or non-adaptive HARQ) suitable for a retransmission environment in order to retransmit an errored packet.

The channel interleaver disperses transmission errors according to channels by mixing encoded packets bit by bit. A physical resource mapper converts interleaved encoded packets into data symbols and maps them to the data region.

4 shows an example of a redundancy version of an encoded packet.

Referring to FIG. 4, an entire bit string of an encoded packet is called a mother codeword, and a mother code generated by applying a turbo code has structural bits having a bit string having the same length as a code block. And at least one parity bit associated with it. When the mother code rate is 1 / R _m and the size of the code block into the encoder is N _EP , the length of the mother code is Rm N _EP . If the encoder uses a Convolutional Turbo Code (CTC) with a double binary (duo-binary) structure, N _EP is the number of bits input to the CTC turbo encoder, which is defined as the size of the encoded packet. Is a parameter. When the size of the internal interleaver of the CTC turbo encoder is N, N _EP = 2 × N. If the mother coding rate is 1/3, the mother code includes one structural bit and two parity bits.

In HARQ in incremental redundancy (IR) mode, a mother code is divided into a plurality of bit string blocks and transmitted in units of bit string blocks. The size of the bit string block may be determined according to the modulation technique applied, resource allocation, and the like. The modulation technique may be determined in various ways, such as binary-phase shift keying (BPSK), quadrature-phase shift keying (QPSK), 16 quadrature amplitude modulation (QAM), and 64 QAM. The bit string block is indicated by a redundancy version (RV). For example, the first bitstream block containing structural bits is RV 0, the second bitstream block contiguous to the first bitstream block is RV 1, and the third bitstream block contiguous to the second bitstream block is RV. The fourth bit string block subsequent to the second and third bit string blocks is indicated by RV 3. At this time, if successive bit string blocks exceed the length of the mother code, the excess portion is cyclically transmitted.

Although the sizes of the bit string blocks of different RVs are the same, the size of the bit string blocks of each RV may be determined differently. For example, in non-adaptive HARQ, the bit string blocks of each RV may be set to the same size, and in adaptive HARQ, the bit string blocks of different RVs may be set to different sizes. One bit string block may be mapped and transmitted in one subframe, and bit string blocks of different RVs may be mapped and transmitted in different subframes.

5 shows data transmission using HARQ.

Referring to FIG. 5, data transmission is performed in units of transmission time interval (TTI). TTI is a transmission time of an encoded packet over an air interface, and the encoded packet is generated at the physical layer. The time from when the transmitter Tx transmits data to the time immediately before receiving the ACK / NACK signal for the data transmission from the receiver Rx and retransmitting the data is called a round trip time (RTT). The RTT includes a processing delay, which is a time required for data processing at the transmitter Tx and the receiver Rx.

In the HARQ process, the ACK / NACK transmission time and the data retransmission time may vary according to the ratio of uplink and downlink in a time division duplex (TDD) frame and processing delay of the terminal / base station. When several HARQ processes are performed between the base station and the terminal, it is necessary to set the HARQ timing to minimize the wasted time resources without overlapping each other in the time domain. Hereinafter, a method of performing HARQ for this will be described. For convenience of explanation, it will be described based on the TDD frame. However, the present invention is not limited thereto, and the technical spirit of the present invention may be extended to the FDD frame.

6 is a flowchart illustrating a method of performing HARQ according to an embodiment of the present invention. For convenience of description, a case in which the base station transmits downlink data to the terminal is illustrated, but is not limited thereto. Even when the terminal transmits uplink data to the base station, the technical idea of the present invention can be applied.

Referring to FIG. 6, the base station and the terminal share HARQ timing (S100). HARQ timing means ACK / NACK transmission time and / or data retransmission time. The ACK / NACK transmission time point may be represented as a time taken from the data transmission time point to the ACK / NACK transmission time, and may be expressed as an ACK channel delay. The data retransmission time point may be represented as a time taken to retransmit data from an initial transmission time point or a time taken to retransmit data from an ACK / NACK transmission time point, and may be expressed as a retransmission channel delay. The ACK channel delay and / or retransmission channel delay may be in subframe units.

The HARQ timing may vary depending on a ratio of a downlink region to an uplink region (hereinafter, referred to as a DL / UL ratio), a processing delay between a base station and a terminal, and a data transmission time point. The DL / UL ratio may be various ratios such as 4: 4, 5: 3, 6: 2, and the like. The processing delay is the time taken to decode the received message. Accordingly, in downlink data transmission, a terminal receiving data from a base station can transmit ACK / NACK at least from the time point at which the processing delay of the terminal has passed. In addition, the base station receiving the NACK from the terminal can retransmit the data at least from the time point of the processing delay of the base station. The processing delay of the base station and the terminal may be the same or different.

As an example of a method of sharing HARQ timing, the base station and the terminal implicitly imply a relationship between the DL / UL ratio, the processing delay of the base station and the terminal, and the time of ACK / NACK transmission and / or data retransmission according to the data transmission time. Share, the base station can inform the terminal of the DL / UL ratio, processing delay between the base station and the terminal and the data transmission time. As another example of a method of sharing HARQ timing, the base station may directly inform the terminal of an ACK / NACK transmission time and / or a data retransmission time. In addition, the base station and the terminal may share HARQ timing according to various embodiments.

At this time, the base station may inform the terminal of the DL / UL ratio, the processing delay between the base station and the terminal and the data transmission time, or the ACK / NACK transmission time and / or the data retransmission time to the terminal through a control channel or a broadcast channel. have. The control channel may be located in the super frame header.

The base station transmits data to the terminal (S110), the terminal transmits ACK / NACK to the base station (S120). In this case, the terminal may transmit ACK / NACK according to the HARQ timing shared with the base station in step S100. If data retransmission is necessary, the base station may retransmit the data according to the HARQ timing shared with the terminal in step S100 (S130).

As such, ACK / NACK transmission and data retransmission of each HARQ process are performed at a predetermined time point. Accordingly, all channels allocated for HARQ can be used without waste.

Hereinafter, an embodiment of HARQ timing will be described. Embodiments described in the present specification are merely exemplary and are not limited thereto. For convenience of description, the description is based on the TDD frame, but this may also be applied to the FDD frame. In addition, although the case of transmitting data in the downlink is illustrated, the technical idea of the present invention can be applied to the case of transmitting data in the uplink.

7 illustrates HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 4: 4. It is assumed that each of the terminal and the base station has a processing delay of at least 3 subframes. If one subframe is assumed to be 1 TTI, the processing delay of each of the terminal and the base station is 3 TTI.

Referring to FIG. 7, SF (subframes) 0 to SF 3 are downlink subframes and SF 4 to SF 7 are uplink subframes in each frame.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 4 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 0 of frame n + 1. Accordingly, RTT is 8 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 1. Accordingly, RTT is 8 subframes.

In the third HARQ channel, data is transmitted in downlink through SF 2 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 1. Accordingly, RTT is 8 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 1. Accordingly, RTT is 8 subframes.

When the processing delay of the base station is 3 subframes and the processing delay of the terminal is 2 subframes or the processing delay of the base station is 2 subframes and the processing delay of the terminal is 3 subframes, the HARQ timing pattern may be the same as 8.

8 and 9 illustrate HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 5: 3. It is assumed that each of the terminal and the base station has a processing delay of at least 3 subframes. If one subframe is assumed to be 1 TTI, the processing delay of each of the terminal and the base station is 3 TTI.

8 and 9, in each frame, SF 0 through SF 4 are downlink subframes, and SF 5 through SF 7 are uplink subframes.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 1. Accordingly, RTT is 9 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 1. Accordingly, RTT is 9 subframes.

In the third HARQ channel, data is transmitted in downlink through SF 2 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 1. Accordingly, RTT is 9 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 1. Accordingly, RTT is 9 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n + 1. Since the processing delay of the terminal is three subframes, it takes three subframes for the terminal to decode the data received from the base station. Accordingly, a time point three subframes from SF 5 of the frame n + 1 is SF 0 of the frame n + 1, and the preceding uplink subframe is SF 5 of the frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 2. Accordingly, the RTT is 13 subframes.

In the sixth HARQ channel, data is transmitted in downlink through SF 0 of frame n + 1 and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 2. Accordingly, the RTT is 10 subframes.

10 illustrates HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3. It is assumed that the base station has a processing delay of at least 3 subframes, and the terminal has a processing delay of at least 2 subframes. If one subframe is assumed to be 1 TTI, the processing delay of the base station is 3 TTI and the processing delay of the terminal is 2 TTI.

Referring to FIG. 10, in each frame, SF 0 through SF 4 are downlink subframes, and SF 5 through SF 7 are uplink subframes.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 0 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the third HARQ channel, data is transmitted in downlink through SF 2 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 54 of frame n + 2. Accordingly, the RTT is 16 subframes.

11 shows HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3. It is assumed that the base station has a processing delay of at least 2 subframes, and the terminal has a processing delay of at least 3 subframes. Assuming one subframe is 1 TTI, the processing delay of the base station is 2 TTIs, and the processing delay of the terminal is 3 TTIs.

Referring to FIG. 11, in each frame, SF 0 through SF 4 are downlink subframes, and SF 5 through SF 7 are uplink subframes.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the third HARQ channel, data is transmitted in downlink through SF 2 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 0 of frame n + 2. Accordingly, the RTT is 13 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 2. Accordingly, the RTT is 13 subframes.

In the seventh HARQ channel, data is transmitted in downlink through SF 1 of frame n + 1 and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 2. Accordingly, the RTT is 10 subframes.

12 illustrates HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 5: 3. It is assumed that the base station has a processing delay of at least 2 subframes, and the terminal has a processing delay of at least 3 subframes. Assuming one subframe is 1 TTI, the processing delay of the base station is 2 TTIs, and the processing delay of the terminal is 3 TTIs.

Referring to FIG. 12, in each frame, SF 0 through SF 4 are downlink subframes, and SF 5 through SF 7 are uplink subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 or SF 6 of frame n. In order to distribute uplink resources evenly, ACK / NACK may be transmitted through SF 5 or SF 6. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 5 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 2. Accordingly, the RTT is 16 subframes.

13 and 14 illustrate HARQ timing according to an embodiment of the present invention when the DL / UL ratio is 6: 2. It is assumed that each of the terminal and the base station has a processing delay of at least 3 subframes. If one subframe is assumed to be 1 TTI, the processing delay of each of the terminal and the base station is 3 TTI.

13 and 14, in each frame, SF (subframe) 0 to SF 5 are downlink subframes, and SF 6 and SF 7 are uplink subframes.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the third HARQ channel, data is transmitted in downlink through SF 2 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. The ACK / NACK transmission may be transmitted through SF 6 of frame n, which is 3 subframes after the downlink data transmission time. However, in order to distribute resources for ACK / NACK transmission evenly, ACK / NACK is transmitted through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 5 of frame n + 1. Accordingly, the RTT is 10 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 1. Since the processing delay of the terminal is three subframes, it takes three subframes for the terminal to decode the data received from the base station. Therefore, a time point 3 subframes from SF 4 of frame n is SF 0 of frame n + 1, and the most uplink subframe therefrom is SF 6 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 2. Accordingly, RTT is 14 subframes.

In the sixth HARQ channel, data is transmitted in downlink through SF 5 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 1. Since the processing delay of the terminal is three subframes, it takes three subframes for the terminal to decode the data received from the base station. Accordingly, a time point three subframes from SF 5 of frame n becomes SF 1 of frame n + 1, and the most uplink subframe therefrom is SF 6 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 2. Accordingly, RTT is 14 subframes.

In the seventh HARQ channel, data is transmitted in downlink through SF 0 of frame n + 1 and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n + 1. Since the processing delay of the UE is 3 subframes, ACK / NACK may be transmitted through SF 6 of frame n + 1. However, since SF 6 of frame n + 1 is used for ACK / NACK transmission in the fifth HARQ channel and the sixth HARQ channel, ACK / NACK is performed through SF 7 of frame n + 1 to distribute resources evenly. send. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 2. Accordingly, the RTT is 12 subframes.

In the eighth HARQ channel, data is transmitted in downlink through SF 1 of frame n + 1, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n + 1. Since the processing delay of the UE is 3 subframes, ACK / NACK may be transmitted through SF 6 of frame n + 1. However, since SF 6 of frame n + 1 is used for ACK / NACK transmission in the fifth HARQ channel and the sixth HARQ channel, ACK / NACK is performed through SF 7 of frame n + 1 to distribute resources evenly. send. If data retransmission is needed, data retransmission is performed in downlink through SF 5 of frame n + 2. Accordingly, the RTT is 12 subframes.

15 to 18 illustrate HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 6: 2. It is assumed that the base station has a processing delay of at least 2 subframes, and the terminal has a processing delay of at least 3 subframes. Assuming one subframe is 1 TTI, the processing delay of the base station is 2 TTIs, and the processing delay of the terminal is 3 TTIs.

15 to 18, in each frame, SF (subframe) 0 to SF 5 are downlink subframes, and SF 6 and SF 7 are uplink subframes.

In the ninth HARQ channel, data is transmitted in downlink through SF 0 of frame n + 2 and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 2. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 3. Accordingly, RTT is 9 subframes.

In the 10th HARQ channel, data is transmitted in downlink through SF 1 of frame n + 2 and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n + 2. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 3. Accordingly, RTT is 9 subframes.

In the eleventh HARQ channel, data is transmitted in downlink through SF 0 of frame n + 3 and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 3. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 4. Accordingly, RTT is 9 subframes.

In the twelfth HARQ channel, data is transmitted in downlink through SF 3 of frame n + 3, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n + 3. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 4. Accordingly, RTT is 7 subframes.

In the thirteenth HARQ channel, data is transmitted in downlink through SF 4 of frame n + 3, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 4. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 5. Accordingly, the RTT is 13 subframes.

In the 14th HARQ channel, data is transmitted in downlink through SF 5 of frame n + 3 and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 4. If data retransmission is needed, data retransmission is performed in downlink through SF 2 of frame n + 5. Accordingly, the RTT is 13 subframes.

19 shows HARQ timing according to another embodiment of the present invention when the DL / UL ratio is 6: 2. It is assumed that the base station has a processing delay of at least 3 subframes, and the terminal has a processing delay of at least 2 subframes. If one subframe is assumed to be 1 TTI, the processing delay of the base station is 3 TTI and the processing delay of the terminal is 2 TTI.

Referring to FIG. 19, SF (subframes) 0 to SF 5 in each frame are downlink subframes, and SF 6 and SF 7 are uplink subframes.

In the first HARQ channel, data is transmitted in downlink through SF 0 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 0 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the second HARQ channel, data is transmitted in downlink through SF 1 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 1 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fourth HARQ channel, data is transmitted in downlink through SF 3 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. The ACK / NACK transmission may be transmitted through SF 6 of frame n, which is 2 subframes after the downlink data transmission time. However, in order to distribute resources for ACK / NACK transmission evenly, ACK / NACK is transmitted through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 3 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the fifth HARQ channel, data is transmitted in downlink through SF 4 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 7 of frame n. If data retransmission is needed, data retransmission is performed in downlink through SF 4 of frame n + 2. Accordingly, the RTT is 16 subframes.

In the sixth HARQ channel, data is transmitted in downlink through SF 5 of frame n, and ACK / NACK is transmitted for the data in uplink through SF 6 of frame n + 1. If data retransmission is needed, data retransmission is performed in downlink through SF 5 of frame n + 2. Accordingly, the RTT is 16 subframes.

Hereinafter, a table summarizing HARQ timing according to an embodiment of the present invention.

Table 1 shows an ACK channel delay according to each DL / UL ratio and data transmission time when the processing delay of the UE is 3 subframes. If a subframe in which downlink data transmission occurs is called SF n, a subframe in which ACK / NACK transmission occurs is SF n + k. k is the number in the table. For example, if the DL / UL ratio is 4: 4 and downlink data transmission occurs in SF 0, ACK / NACK transmission may be interpreted as occurring in SF (0 + 4). In addition, when the DL / UL ratio is 6: 2 and downlink data transmission occurs in SF 4, ACK / NACK transmission occurs in SF (4 + 10), that is, in the next frame SF 6 of the frame in which downlink data transmission occurs. It can be interpreted as.

TABLE 1

Table 2 shows an ACK channel delay according to each DL / UL ratio and data transmission time when the processing delay of the UE is 2 subframes.

TABLE 2

20 is a block diagram illustrating a transmitter and a receiver for transmitting and receiving data using a method of performing HARQ according to an embodiment of the present invention.

Referring to FIG. 20, the transmitter 100 includes a HARQ processor 110 and a radio frequency (RF) unit 120, and the receiver 200 includes a HARQ processor 210 and a radio frequency (RF) unit 220. It includes. The RF unit 120 is connected to the HARQ processor 110 to transmit and receive a radio signal, and the RF unit 220 is connected to the HARQ processor 210 to transmit and receive a radio signal. The HARQ processor 210 of the receiver 200 receives data from a base station, and transmits an ACK / NACK for the data to the base station at a point in time passed from the time point at which the data is transmitted from the base station. The HARQ processor 110 of the transmitter 100 transmits data to a terminal, receives a non-acknowledgement (NACK) signal for the data transmission from the terminal, and passes a predetermined period from the time when the NACK signal is transmitted. At this point, the data is retransmitted to the terminal. Information about the predetermined period may be shared between the transmitter and the receiver. In downlink data transmission, a transmitter may be a base station and a receiver may be a terminal.

The present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- , Other electronic units, or a combination thereof. In the software implementation, the module may be implemented as a module that performs the above-described function. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

As mentioned above, preferred embodiments of the present invention have been described in detail, but those skilled in the art to which the present invention pertains should understand the present invention without departing from the spirit and scope of the present invention as defined in the appended claims. It will be appreciated that various modifications or changes can be made. Accordingly, modifications of the embodiments of the present invention will not depart from the scope of the present invention.

Claims

In a method of performing HARQ of a terminal in a wireless communication system,
Receiving data from a base station; and
And transmitting an ACK / NACK for the data to the base station at a time after a predetermined period from the time point at which the data is transmitted from the base station.
The information about the predetermined period is HARQ performing method between the base station and the terminal.

The method of claim 1,
And the information on the predetermined period includes at least one of the predetermined period and information for determining the predetermined period.

The method of claim 2,
The information for determining the predetermined period includes at least one of a ratio of an uplink region and a downlink region in a time division duplex (TDD) frame, a processing delay of the terminal, a processing delay of the base station, and a time point at which the data is transmitted from the base station. HARQ method, characterized in that at least one.

The method of claim 1,
And receiving a control signal including information on the predetermined period from the base station.

The method of claim 4, wherein
And the control signal is transmitted through a super frame header.

The method of claim 1,
The predetermined period according to the ratio of the uplink region and the downlink region in the TDD frame and the time point at which the data is transmitted is as shown in the table below.

In a method of performing HARQ of a base station in a wireless communication system,
Transmitting data to the terminal;
Receiving a non-acknowledgement (NACK) signal for the data transmission from the terminal; And
And retransmitting the data to the terminal at a time after a predetermined period from the time when the NACK signal is transmitted,
The information about the predetermined period is HARQ performing method between the base station and the terminal.

The method of claim 8,
The predetermined period of time is determined based on at least one of a ratio of an uplink region and a downlink region in a TDD frame, a processing delay of the terminal, a processing delay of the base station, and a time point at which the data is transmitted from the base station. HARQ performing method.

RF (Radio Frequency) unit; And
Including a processor connected to the RF unit,
The processor receives data from a base station, and transmits an ACK / NACK for the data to the base station at a point in time after a predetermined period has elapsed from the time point at which the data is transmitted from the base station, wherein the information on the predetermined period is Terminal shared between the base station and the terminal.