KR100889863B1 - Data retransmission method for mobile communication system - Google Patents

Abstract

The present invention relates to a data retransmission method of a mobile communication system. In particular, in a mobile communication system using a plurality of antennas, another diversity gain between antennas is changed by changing the positions of symbols transmitted to the plurality of antennas when retransmission occurs. The purpose is to improve the call quality by obtaining. In the mobile communication system for transmitting and receiving signals using a plurality of antennas, a first step of determining whether there is a retransmission request from the receiving side while transmitting symbols to the plurality of antennas, and the receiving side If there is a retransmission request from the process, the process of dividing the retransmission symbol into the even and odd symbols, the position of the even symbol transmitted by multiple antennas, and the position of the odd symbol transmitted by multiple antennas It is characterized by performing a second step consisting of a process of transmitting sequentially to different from each other.

Description

Data retransmission method of mobile communication system {DATA RETRANSMISSION METHOD FOR MOBILE COMMUNICATION SYSTEM}

1 is a table showing a symbol transmitted to each antenna of the prior art.

2 is a table showing a symbol retransmitted to each antenna in the first embodiment of the present invention;

3 is a table showing symbols retransmitted to each antenna in the second embodiment of the present invention;

4 is a table showing symbols retransmitted to each antenna in the third embodiment of the present invention;

The present invention relates to a mobile communication system, and more particularly, to a data retransmission method in a mobile communication system using a plurality of transmit antennas and a plurality of receive antennas.

Currently, the Space Time Transmit Diversity (STTD) scheme is adopted as an open-loop transmit diversity scheme within the Third Generation Partnership Project (3GPP).

The STTD method is a technique for obtaining diversity effects through space-time coding that extends a channel coding technique mainly applied on a time axis into a space.

Since the STTD method does not require a feedback signal, there is no merit of performance change depending on the speed, and it is applicable to all downlink physical channels except the SCH of WCDMA.

Conventional STTD is configured to use both antennas to obtain not only temporal diversity gain but also spatial diversity gain through space-time simple coding between symbols transmitted on the two antennas.

In the prior art, a space-time coding block is provided for coding between symbols transmitted by two antennas.                         

The operating principle of the conventional STTD technology is shown in the table of FIG.

That is, according to the conventional STTD technology, as shown in FIG. 1, STTD encoding of a symbol to be transmitted is performed through two antennas (Antenna 0, 1) according to a time t (t + T) order. Where T is a symbol period.

Signals transmitted to each antenna 0,1 pass through different independent channels.

If it is assumed that the channel at time t and the channel at time t + T are the same, the signal received at the receiving antenna stage is expressed by Equation 1 below.

,

은 각각 송신 안테나(Antenna 0,1)과 수신 안테나 간의 채널을 의미하며,

,

은 수신단에서의 복소 잡음을 의미한다. here,

,

Denote channels between the transmitting antennas (Antenna 0, 1) and the receiving antennas, respectively.

,

Means complex noise at the receiver.

However, each channel can be estimated as a pilot signal.

Therefore, the received signal can obtain the same value as the maximum ratio combining method (MRC) of the reception diversity, and can estimate the transmitted symbol as shown in Equation 2 below.

On the other hand, as the data transmission technology has been introduced to the packet data retransmission technique, a technique using a correction code and a technique for requesting retransmission by detecting an error as a method for securing the reliability of the data transmission.

The technique using the correction code is a method of using a surplus code called a self-correction code method to detect and recover an error of the number of bits within the surplus bit by itself. There is a method of determining whether there is an error by repeatedly transmitting the same data two or more times and then correcting it when an error occurs.

The technique for detecting the error and requesting retransmission is called a retransmission feedback method. In this method, the receiver sends information received from the sender back to the sender to determine whether there is an error and then retransmits the error. A simple information feedback method and an automatic repeat request (ARQ) method in which the receiving side checks whether there is an error in the data transmitted from the transmitting side, informs the transmitting side whether an error has occurred, and resends the data in which the transmitting side has an error have.

As an error detection code method for checking whether an error of data received from a transmitter is transmitted from a receiver, a parity check method of determining whether an error is performed using an extra bit of 1 bit as a check bit, and a CRC code in blocks In addition, there is a cyclic redundancy check method for transmitting.

In addition, the automatic repeat request (ARQ) scheme includes a stop-and-wait ARQ, a continuous ARQ, an adaptive ARQ, and the like.                         

In the stop-standby ARQ method, when a transmitting block transmits one data block, the receiving side determines whether there is an error in the receiving block and transmits a retransmission request signal (hereinafter referred to as NACK) when an error occurs. If not, the reception acknowledgment signal (hereinafter referred to as ACK) is transmitted to the transmitting side. When the transmitting side receives the ACK signal from the receiving side, the next block is transmitted. If there is no response, it is a simple way to retransmit the block. This method has a disadvantage in that communication efficiency is lowered because the receiver must wait for a response each time a block is transmitted.

The continuous ARQ scheme is to compensate for the shortcomings of the stop-standby ARQ scheme. When the NACK signal is transmitted from a receiver and a plurality of data blocks are transmitted, Go-Back retransmits all subsequent blocks from the block receiving the NACK signal. There is a NARQ scheme and a selective repeat ARQ scheme of retransmitting only a block receiving a NACK signal.

The adaptive ARQ scheme is a technique for dynamically changing a block length in order to increase transmission efficiency. The adaptive ARQ scheme transmits an error occurrence rate from a receiving side to a transmitting side and adjusts an appropriate block length at the transmitting side. Technique.

The transmission efficiency of the adaptive ARQ scheme is best among the stop-standby ARQ, continuous ARQ, and adaptive ARQ schemes briefly described above.

The above-described automatic repeat request (ARQ) scheme can be equally applied to a wireless packet communication system.

There are a variety of methods available for automatic repeat request (ARQ).

In a simple manner, a method of transmitting an ACK or NACK signal to a transmitter according to whether the receiver receives data correctly and determining whether to retransmit the data can be applied.

The ACK or NACk signal may be defined as a 1-bit signal.

In this method, when the receiving side transmits an 1-bit ACK signal (for example, "1"), the transmitting side determines that the transmitted packet is correctly received. In contrast, the receiving side transmits a NACK signal (for example, "-1"). When transmitting, the sender determines that the reception of the packet has failed and retransmits the corresponding data packet.

However, although the prior art uses diversity in time and diversity in space, since retransmission does not consider symbol positions between antennas, call quality may be degraded due to estimation error of a transmission symbol when fading occurs. There is a disadvantage.

Therefore, in the mobile communication system using a plurality of antennas in order to improve the disadvantages of the prior art, in order to obtain another diversity gain between antennas by changing the position of symbols transmitted to the plurality of antennas when retransmission occurs. It is an object of the present invention to provide a data retransmission method of a mobile communication system invented to improve call quality.                         

That is, the present invention is to improve the call quality by improving the estimation performance of the transmission symbols by obtaining the diversity for another antenna by changing the position of the symbols transmitted from the two antennas when retransmission occurs will be.
The present invention is characterized in that in the mobile communication system using the HARQ scheme to achieve the above object, when using the STTD, the position of the symbol to be retransmitted to a plurality of antennas are transmitted in space every time retransmission occurs. .
In addition, the present invention in the mobile communication system using the HARQ scheme to achieve the above object, when using the STTD, the position of the symbol to be retransmitted to a plurality of antennas each time a retransmission occurs in one symbol period in time It transmits by changing.
In addition, in the mobile communication system using the HARQ scheme in order to achieve the above object, when the STTD scheme is used, whenever the retransmission occurs, the encoding position of the symbol to be transmitted to a plurality of antennas are changed to retransmit the encoded symbol. Characterized in that.

The present invention is applied to a mobile communication system. However, the present invention is not limited thereto and may be applied to all communication systems to which the technical spirit of the present invention is applied.
In order to achieve the object of the present invention, the configuration and technical means of the present invention are as follows. That is, a data retransmission method of a mobile communication system that transmits and receives signals using two antennas, the method comprising: transmitting a first symbol through a first antenna and transmitting a second symbol through a second antenna; Retransmitting the second symbol through the first antenna and retransmitting the first symbol through the second antenna when retransmitting the first symbol and the second symbol for a first time period; It features.
Preferably, retransmitting the first symbol through the first antenna and retransmitting the second symbol through the second antenna when retransmitting the first symbol and the second symbol for a second time; It characterized in that it further comprises.
Preferably, the first time is a time when the first symbol and the second symbol to be retransmitted are odd-retransmitted.
Preferably, the second time is a time when the retransmitted first symbol and the second symbol are retransmitted evenly.
Preferably, the method may further include determining whether a request for retransmission of the transmitted first and second symbols is received from a receiving side.
The method may further include determining whether the first symbol and the second symbol to be retransmitted are even-numbered or odd-numbered retransmissions.
A data retransmission method of a mobile communication system according to the present invention is a data retransmission method of a mobile communication system that transmits and receives a signal using two antennas, when a request for retransmission of symbols transmitted from a receiver is transmitted, retransmission is performed to an antenna. A method of retransmitting by changing positions of symbols to be performed for each of the two antennas,
In the case of a first retransmission, transmitting a second symbol via a first antenna and transmitting a first symbol via a second antenna; In case of a second retransmission, the method may include transmitting the first symbol through the first antenna and transmitting the second symbol through the second antenna.
A data retransmission method of a mobile communication system according to the present invention includes a method of retransmitting a data using a plurality of antennas, the method comprising: transmitting symbols to the plurality of antennas; And changing and repositioning symbols to be retransmitted to the plurality of antennas.
The method may further include determining whether there is a request for retransmission of the transmitted symbols from a receiver.
Preferably, the method may further include determining whether the symbols to be retransmitted are even (even) or odd (odd).
Preferably, the symbols to be retransmitted are odd.
Preferably, the positions of the symbols to be retransmitted are transmitted for each of the plurality of antennas.
Preferably, the transmission positions of the symbols to be retransmitted are transmitted in time.
Preferably, the encoding order of the symbols to be retransmitted is changed and the encoded symbols are transmitted.
Preferably, the symbols to be retransmitted are characterized in that the transmission using the Space Time Transmit Diversity (STTD) scheme.
Preferably, the transmission position of the symbols to be retransmitted is transmitted by changing the symbol period.
Preferably, the symbols to be retransmitted is characterized in that the transmission using a hybrid automatic repeat reQuest (HARQ) scheme.
In addition, according to an embodiment of the present invention, a data retransmission method of a mobile communication system according to the present invention is a data retransmission method of a mobile communication system that transmits and receives a signal using a plurality of antennas. Transmitting them; And changing and transmitting positions of symbols to be retransmitted to the plurality of antennas for each of the plurality of antennas, wherein the symbols to be retransmitted are odd.
In addition, according to an embodiment of the present invention, a data retransmission method of a mobile communication system according to the present invention is a data retransmission method of a mobile communication system that transmits and receives signals using two antennas, and includes a first antenna through a first antenna. Transmitting one symbol;
Transmitting a second symbol via a second antenna; Retransmitting the second symbol via the first antenna; And retransmitting the first symbol through the second antenna, wherein the retransmitted first symbol and the second symbol are an odd number of times.

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Hereinafter, the present invention will be described in detail with reference to the drawings.

In the embodiments of the present invention, a detailed description of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

In the embodiment of the present invention will be described for the case of applying a hybrid ARQ (hybrid ARQ) method.                     

HARQ is an incremental redundancy method that combines forward error correction (FEC) and ARQ (auto retransmission).

Typically, the HARQ scheme uses convolution codes used for forward error correction (FEC) in combination with the ARQ scheme.

The configuration for the embodiment of the present invention is generally the same as the prior art, but since HARQ (mixed automatic retransmission) is assumed, a circuit block responsible for HARQ is included in the transmitting end.

Since an embodiment of the present invention assumes a mobile communication system using the HARQ scheme, when retransmission of a symbol is required from a receiver when using a STTD, two antennas are changed by changing positions of symbols to be retransmitted by two antennas in a circuit block for HARQ. Independence between the two antennas is used to obtain the diversity gain between the two antennas.

The operation and the effect of the embodiment of the present invention configured as described above will be described with reference to the tables of FIGS.

The first embodiment of the present invention is to retransmit by changing the position of the symbol to be retransmitted to each antenna as shown in the table of FIG.

That is, in case of retransmission, the first embodiment of the present invention transmits the STTD encoded symbol in the same manner as the prior art for the first transmission and the even-numbered retransmission, and the position of the symbol transmitted by the two antennas for the odd-numbered retransmission. In other words, the independence between the two antennas is used.

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하며 홀수번째 전송시 각각의 안테나(Antenna 0,1)로 전송될 심볼의 위치를 도2(a)와는 반대로 도2(b)와 같이 바꾸어 시간(t) 동안 심볼(

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하는 것이다. In other words, in the first embodiment of the present invention, when retransmission occurs, the symbol < RTI ID = 0.0 > (i) < / RTI >

) (

) And the symbol (for time t + T)

) (

In the odd-numbered transmission, the symbol position to be transmitted to each antenna (Antenna 0, 1) is changed as shown in FIG. 2 (b) as opposed to FIG.

) (

) And the symbol (for time t + T)

) (

) Is sent.

The second embodiment of the present invention retransmits by changing the position of a symbol to be retransmitted on time t (t + T) as shown in the table of FIG.

That is, in the second embodiment of the present invention, when retransmission occurs, the symbols to be transmitted to the two antennas (Antenna 0,1) are the same as before the retransmission occurs, but the positions of the symbols to be retransmitted are interchanged with each other in the symbol period.

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하며 홀수번째 전송시 각각의 안테나(Antenna 0,1)로 전송될 심볼의 위치를 도3(b)와 같이 시간(t)(t+T) 상으로 바꾸어 시간(t) 동안 심볼(

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하는 것이다. In other words, in the second embodiment of the present invention, when retransmission occurs, the symbol < RTI ID = 0.0 > (i) < / RTI >

) (

) And the symbol (for time t + T)

) (

) And the position of the symbol to be transmitted to each antenna (Antenna 0,1) during odd-numbered transmission is changed over time (t) (t + T) as shown in FIG.

) (

) And the symbol (for time t + T)

) (

) Is sent.

A third embodiment of the present invention is to change the STTD encoding order for symbols to be retransmitted as shown in the table of FIG.                     

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하며 홀수번째 전송시 각각의 안테나(Antenna 0,1)로 전송될 심볼의 STTD 인코딩 위치를 바꾸어 도4(b)와 같이 시간(t) 동안 심볼(

)(

)을 전송하고 시간(t+T) 동안 심볼(

)(

)을 전송하는 것이다. That is, in the third embodiment of the present invention, when retransmission occurs, the symbol (for each antenna (Antenna 0,1) for the time t as shown in FIG.

) (

) And the symbol (for time t + T)

) (

) And change the STTD encoding position of the symbol to be transmitted to each antenna (Antenna 0,1) in odd-numbered transmissions.

) (

) And the symbol (for time t + T)

) (

) Is sent.

As described in detail above, the present invention uses a plurality of antennas by using independence between a plurality of antennas by changing the position of a symbol to be retransmitted to a plurality of antennas when using STTD in a mobile communication system using the HARQ scheme. Diversity gain between antennas can be obtained.

Accordingly, the present invention has an effect of improving call quality by reproducing a signal by accurately estimating a transmission symbol even when a fading phenomenon occurs.

Claims (12)

In the data retransmission method of a mobile communication system for transmitting and receiving signals using two antennas, Transmitting a first symbol via a first antenna and transmitting a second symbol via a second antenna; When retransmitting the first symbol and the second symbol for a first time, Retransmitting the second symbol through the first antenna and retransmitting the first symbol through the second antenna; When retransmitting the first symbol and the second symbol for a second time, Retransmitting the first symbol through the first antenna and retransmitting the second symbol through the second antenna; The first time is a time at which the first symbol and the second symbol to be retransmitted are odd-retransmitted, The second time is a data retransmission method of the mobile communication system, characterized in that the first symbol and the second symbol is retransmitted evenly (even) times. delete delete delete The method of claim 1, further comprising: determining whether a request for retransmission of the transmitted first and second symbols is received from a receiving side. 6. The method of claim 5, further comprising determining whether the first symbol and the second symbol to be retransmitted are even-numbered or odd-numbered retransmissions. 7. . delete The method of claim 1, wherein the first symbol and the second symbol to be retransmitted are transmitted using a Space Time Transmit Diversity (STTD) scheme. The data retransmission method of claim 5, wherein the transmission position of the symbols to be retransmitted is changed for one symbol period. The method of claim 1, wherein the first symbol and the second symbol to be retransmitted A method for retransmitting data in a mobile communication system, characterized in that it is transmitted using a HARQ (Hybrid Automatic Repeat reQuest) method. In the data retransmission method of a mobile communication system for transmitting and receiving signals using two antennas, When there is a request for retransmission of symbols transmitted from a receiver, a method of retransmitting by changing positions of symbols to be retransmitted to an antenna for each of the two antennas, In the case of a first retransmission, transmitting a second symbol via a first antenna and transmitting a first symbol via a second antenna; In case of a second retransmission, transmitting the first symbol through the first antenna and transmitting a second symbol through the second antenna; The first retransmission is that the transmitting side retransmits the first symbol and the second symbol to the receiving side in odd number (odd), In the second retransmission, the transmitting side retransmits the first symbol and the second symbol evenly to the receiving side. delete

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