KR20090089505A - Method of data transmission using multiple antenna - Google Patents

Abstract

A data communications method using a multiple antenna which transmits parity bit data is provided to improve data transmission performance by transmitting data through different transmission antenna according to a channel state. A code block which is composed of a system bit and parity bit is transmitted through a first transmitting antenna(140). A second symbol corresponding to the parity bit is transmitted through the second transmission antenna. The re-transmission request about the code block is received. The first and the second symbol is retransmitted through the first or the second transmission antenna.

Description

Data transmission method using multiple antennas {Method of Data Transmission using Multiple Antenna}

The present invention relates to wireless communication, and more particularly, to a data transmission method using multiple antennas.

Recently, there has been an explosive increase in demand for wireless data services. And the evolution from wireless voice services to wireless data services requires a gradual increase in wireless capacity. This demand encourages wireless service providers and wireless equipment manufacturers to seek improvements in data rates for wireless systems, and motivates massive research.

The wireless channel has various problems such as path loss, shadowing, fading, noise, limited bandwidth, power limitation of the terminal, and interference between different users. Suffers. This limitation makes the wireless channel look like a narrow pipe that hinders the fast flow of data and makes it difficult to design an efficient bandwidth for wireless communication that provides high speed data transmission. Other challenges in the design of wireless systems include resource allocation, mobility issues related to rapidly changing physical channels, portability, and providing security and privacy. Include design.

When a transmission channel undergoes deep fading, the receiver is difficult to determine the transmitted signal unless another version or replica of the transmitted signal is transmitted separately. The resources corresponding to these different versions or copies are called diversity and are one of the most important factors contributing to reliable transmission over the radio channel. By using such diversity, data transmission capacity or data transmission reliability can be maximized. A system that implements diversity using multiple transmission antennas and multiple reception antennas is called a multiple input multiple output (MIMO) system. The MIMO system is also called a multiple antenna system.

Thus, the transmitter has N transmit antennas and the receiver has M receive antennas. Space-Time Coding (hereinafter referred to as STC) may control what data is transmitted from each of the N transmit antennas. The space-time encoding function of the transmitter processes the data to be transmitted and generates unique information to transmit in the N transmit antennas. Each of the M receive antennas receives signals transmitted from each of the N transmit antennas. The space-time decoding function of the receiver combines the information sent from the N transmit antennas to generate data.

STC can typically be implemented using one of several MIMO techniques. The technique of one embodiment encodes the same data in different formats for different transmit antennas. That is, the same data is transmitted in different formats at each of the N transmit antennas. This is called space-time transmit diversity (STTD). Another technique is to transmit different data from different N transmit antennas, and redundancy in the STTD scheme is avoided. This is called a vertical-bell laboratories layered space time (V-BLAST) technique.

The STTD technique is effective for increasing diversity gain, but there is an inefficiency because redundancy is necessary. The V-BLAST technique improves system throughput for systems that are capable of sufficient diversity. If any threshold diversity is achieved in a BLAST system, the data rate theoretically increases in proportion to the number of transmit / receive antennas, while in STTD systems the additional spatial diversity does not significantly affect the data rate.

An error compensation scheme for securing communication reliability is a hybrid automatic repeat request (HARQ) scheme. The HARQ system improves performance by checking whether data received by the physical layer includes an error that cannot be decoded, and requesting retransmission when an error occurs. In the HARQ scheme, if an error is not detected in the received data, the receiver transmits an acknowledgment (ACK) signal as a response signal to inform the transmitter of the reception success. When an error is detected in the received data, the receiver transmits a negative-acknowledgement (NACK) signal as a response signal to inform the transmitter of the error detection. The transmitter may retransmit data when the NACK signal is received.

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.

Much research has been done by those skilled in the art regarding HARQ. However, HARQ has not been studied in the transmission using multiple antennas. This is partly due to the fact that signals transmitted from different antennas in the space-time channel overlap each other, which makes it difficult to improve the transmitted signal with HARQ. On the other hand, even if HARQ can be used, due to the time delay between the initial transmission and retransmission of the data packet (orthogonality) of the equivalent channel may be broken, causing performance degradation. In this respect, there is a need for a data transmission method using multiple antennas that can improve data retransmission performance.

An object of the present invention is to provide a data transmission method using multiple antennas.

According to an aspect of the present invention, a data transmission method using multiple antennas is provided. Transmitting a first symbol corresponding to the structural bit from a code block including a structural bit and a parity bit through a first transmitting antenna, and a symbol corresponding to the structural bit And transmitting a second symbol corresponding to the parity bit through a second transmit antenna.

According to another aspect of the present invention, there is provided a data transmission method using HARQ in a multi-antenna system. Dividing a code block into structural bits and parity bits, transmitting the structural bits through a first transmit antenna, transmitting the parity bits through a second transmit antenna, and receiving a retransmission request for the code block. And space-time encoding the structural bits and the parity bits and retransmitting them through the first and second transmit antennas.

In transmitting data using HARQ in a multi-antenna system, data is divided into structural bits and parity bits, and the data are differentiated according to channel conditions and transmitted through different transmission antennas, thereby achieving easy data implementation and improved data transmission performance. Can be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like numbers refer to like elements throughout.

1 is a block diagram illustrating a wireless communication system. Wireless communication systems are widely deployed to provide various communication services such as voice and packet data.

Referring to FIG. 1, a wireless communication system includes a user equipment (UE) 10 and a base station 20 (BS). The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device. The base station 20 generally refers to a fixed station that communicates with the terminal 10, and in other terms, such as a Node-B, a Base Transceiver System, or an Access Point. Can be called. One or more cells may exist in one base station 20.

Hereinafter, downlink (DL) means communication from the base station 20 to the terminal 10, and uplink (UL) means communication from the terminal 10 to the base station 20. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20.

The wireless communication system may be an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) based system. OFDM uses multiple orthogonal subcarriers. OFDM uses orthogonality between inverse fast fourier transforms (IFFTs) and fast fourier transforms (FFTs). At the transmitter, data is transmitted by performing an IFFT. The receiver performs FFT on the received signal to recover the original data. The transmitter uses an IFFT to combine multiple subcarriers, and the receiver uses a corresponding FFT to separate multiple subcarriers.

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

Referring to FIG. 2, 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 (CRC attachment). . The information block may be referred to as a Protocol Data Unit (PDU) of Medium Access Control (MAC). The MAC PDU is a data unit transmitted from the upper layer MAC layer to the physical layer when a layer that performs HARQ is called a physical layer.

The transport block to which the CRC is added is segmented into an appropriate size for channel coding (Code block segmentation). The divided block is called a code block. A code block is a data block of a certain size for performing channel coding. Code blocks may have the same size, and a plurality of code blocks may have different sizes.

An encoder performs channel encoding on a code block and outputs coded bits. The encoder can apply a turbo code, which is one of the error correction codes. The turbo code generates structural bits and parity bits in bit units from an input code block. In this case, it is assumed that one structural block S and two parity blocks P1 and P2 are output assuming a 1/3 code rate. A structural block is a set of structural bits, and a parity block is a set of parity bits. The error correction code is not limited to a turbo code, but the technical idea of the present invention can be applied to a low density parity check code (LDPC) or other convolutional codes.

One HARQ function is performed on a transport block basis. The HARQ processor performs an HARQ mode (chase combined or IR) and an HARQ scheme (adaptive HARQ or non-adaptive HARQ) in accordance with the retransmission environment in order to retransmit an errored packet.

The channel interleaver performs interleaving on channel coded code blocks to reduce the effects of burst errors that occur as they are transmitted over a wireless channel. A physical resource mapper converts the interleaved encoded bits into data symbols and maps them to subbursts in the data area. The channel interleaver may perform interleaving on the structural block S and each of the two parity blocks P1 and P2.

3 is a block diagram illustrating an example of a data transmission method in STC. The data bits transmitted here are converted into symbols through mapping. Hereinafter, retransmission means retransmission in performing HARQ.

Referring to FIG. 3, the transmitter includes two transmit antennas (first and second transmit antennas), and symbols S ₁ , S ₂ , -S ₂ ^* ,... Suppose that is sent to. It is also assumed that the symbols are distributed to the two transmit antennas by a specific pattern. During the first transmission period symbol S ₁ is transmitted at the first transmit antenna and at the same time symbol S ₂ is transmitted at the second transmit antenna.

For convenience of explanation, retransmission is interpreted on a symbol-by-symbol basis. However, one of ordinary skill in the art will appreciate that retransmission is retransmission of a group of symbols corresponding to all or part of the data packet being transmitted. Herein, it is assumed that the receiver includes an STC decoder, and the STC decoder provides BLAST decoding for decoding symbols transmitted at every transmission time.

If the receiver fails to decode the symbols S ₁ and S ₂ transmitted at the initial transmission time, the receiver informs the transmitter of the failure (NACK). That is, the receiver requests retransmission to the transmitter. The transmitter receiving the retransmission responds by simply transmitting symbols -S ₂ ^* and S ₁ through the first transmit antenna and the second transmit antenna, respectively, during the first retransmission period. Here, S ₁ ^* and S ₂ ^* are complex conjugates of S ₁ and S ₂ , respectively.

In this case, bits corresponding to the symbols S ₁ and S ₂ of the initial transmission period and bits corresponding to the symbols S ₂ ^* and S ₁ of the first retransmission period are trace coupling means (Chase) of the receiver. Combiner) to recover the original data by gaining in terms of the received energy of the original data or the received signal-to-noise ratio (SNR).

If the receiver fails to decode the symbols S ₁ and S ₂ transmitted at the initial transmission time even with the symbols -S ₂ ^* and S ₁ received during the first retransmission time, the receiver indicates retransmission of the code block. Request to the transmitter. The transmitter receiving the retransmission request responds by transmitting symbols S ₁ and S ₂ through the first transmit antenna and the second transmit antenna, respectively, during the second retransmission period. As described above, the symbols S ₂ ^* and S ₁ are transmitted during the odd-numbered retransmission period, and the symbols S ₁ and S ₂ are transmitted during the even-numbered retransmission period, thereby increasing the probability of data restoration.

4 is a block diagram illustrating another example of a data transmission method in STC.

Referring to FIG. 4, the transmitter includes three transmit antennas (first to third transmit antennas), and symbols S ₁ , S ₂ , S ₃ , -S ₂ ^* , S ₃ ^* ,. Assume that it is transmitted to the receiver through two transmit antennas. During the initial transmission period, symbol S ₁ is transmitted at the first transmit antenna and at the same time symbol S ₂ is transmitted at the second transmit antenna, while symbol S ₃ is transmitted at the third transmit antenna.

The symbol S _{1 ,} S ₂ transmitted by the receiver at the initial transmission time And if the decoding of S ₃ fails, the receiver requests the transmitter to retransmit the code block. For the retransmission request, the transmitter simply sends symbols -S ₂ ^* , S ₁ during the first retransmission period. And S ₃ ^* through the first transmit antenna, the second transmit antenna, and the third transmit antenna, respectively. On the other hand, if the transmitter fails to decode the data despite the retransmission of the symbol during the first retransmission period, the transmitter transmits symbols S _{1 and} S ₂ during the second retransmission period. And S ₃ by transmitting through the first transmit antenna, the second transmit antenna, and the third transmit antenna, respectively.

As such, during the retransmission period corresponding to the odd numbered symbols _, symbols S _{1 and} S ₂ transmitted during the initial transmission period. And S ₃ , and the symbol -S ₂ ^* , S ₁ during the even retransmission period. And S ₃ ^* . Space-time coded redundancy designed to be orthogonal is retransmitted in the first and second transmit antennas, and conjugate redundancy is retransmitted in the third transmit antenna.

5 is a block diagram illustrating a data transmission method in an STC according to an embodiment of the present invention.

Referring to FIG. 5, the transmitter includes two transmit antennas (first and second transmit antennas). Hereinafter, it is assumed that a symbol corresponding to a systematic bit is S ^S and a symbol corresponding to a parity bit is S ^P. Therefore, it is assumed that a code block is first divided into a structural block and a parity block. The transmitter divides the code block into structural blocks and parity blocks.

Although the unit of data to be transmitted or retransmitted may be interpreted in terms of structural bits and parity bits, it will be interpreted on a symbol-by-symbol basis for convenience of description. However, one of ordinary skill in the art will appreciate that retransmission is retransmission of a group of symbols corresponding to all or part of the data packet being transmitted.

During the initial transmission period, a symbol S ₁ ^S corresponding to a structural bit is transmitted from the first transmit antenna, and at the same time, a symbol S ₂ ^P corresponding to a parity bit is transmitted from the second transmit antenna. If the receiver fails to decode the symbols S ₁ ^S and S ₂ ^P transmitted during the initial transmission, the failure is notified to the transmitter. That is, the receiver requests retransmission to the transmitter. The transmitter receiving the retransmission responds by transmitting symbols -S ₂ ^{P *} and S ₁ ^{S *} via the first transmit antenna and the second transmit antenna, respectively, during the first retransmission period.

If the receiver fails to decode the symbols S ₁ ^S and S ₂ ^P transmitted at the initial transmission time even by the symbols -S ₂ ^{P *} and S ₁ ^{S *} received during the first retransmission period, the transmitter indicates the failure. To tell. In response to this, the transmitter responds by retransmitting symbols S ₁ ^S and S ₂ ^P through the first transmission antenna and the second transmission antenna, respectively, during the second retransmission period. In this way, the symbols -S ₂ ^{P *} and S ₁ ^{S *} are transmitted during the odd-numbered retransmission period, and the symbols S ₁ ^S and S ₂ ^P are transmitted during the even-numbered retransmission period. Can increase the probability of restoration.

Meanwhile, a method of determining which transmit antenna to transmit a symbol corresponding to a structural bit and a symbol corresponding to a parity bit is as follows. As an example, it is possible to determine which symbol to transmit to which transmit antenna using the channel state information of the first and second transmit antennas fed back from the receiver. That is, a symbol corresponding to a structural bit may be transmitted from a transmission antenna having a relatively good channel state among the first and second transmission antennas, and a symbol corresponding to a parity bit may be transmitted from a transmission antenna having a relatively poor channel state. Alternatively, a symbol corresponding to a parity bit may be transmitted from a transmission antenna having a relatively good channel state, and a symbol corresponding to a structural bit may be transmitted from a transmission antenna having a relatively poor channel state.

As described above, HARQ performance in the STC can be improved by separating symbols corresponding to structural bits and symbols corresponding to parity bits and transmitting them from different antennas.

6 is a block diagram illustrating a data transmission method in an STC according to another embodiment of the present invention.

Referring to FIG. 6, the transmitter includes two transmit antennas (first and second transmit antennas). Table 1 shows the symbol combinations transmitted at each transmission antenna. Hereinafter, if a symbol transmitted from the first transmission antenna is A and a symbol transmitted from the second transmission antenna is B, a symbol combination transmitted from each transmission antenna will be represented as {A, B} every transmission period.

First time to send First resend time Second retransmission time Third retransmission time First transmitting antenna S ₁ ^S -S ₂ ^{P *} S ₁ ^P -S ₂ ^{S *} Second transmitting antenna S ₂ ^P S ₁ ^{S *} S ₂ ^S S ₁ ^{P *}

Referring to Table 1, it is assumed that the channel state of the first transmitting antenna is relatively excellent from the initial transmission time to the third retransmission time. At the time of initial transmission, the transmitter transmits the symbol combination {S ₁ ^S , S ₂ ^P }. If the receiver fails to receive the symbol combination {S ₁ ^S , S ₂ ^P }, the transmitter transmits the symbol combination {-S ₂ ^{P *} , S ₁ ^{S *} } at the first retransmission time. The symbol combination {S ₁ ^S , S ₂ ^P } and the symbol combination {-S ₂ ^{P *} , S ₁ ^{S *} } maintain orthogonality with each other, and the symbol combination {-S ₂ ^{P *} , S ₁ ^{S *} } Corresponds to the space-time coded redundancy of the symbol combination {S ₁ ^S , S ₂ ^P }.

The transmitter transmits the symbol combination {S ₁ ^P , S ₂ ^S } at the second retransmission time. Combined gain for parity bits by transmitting a symbol corresponding to a parity bit through a first transmit antenna having a relatively good channel state compared to the symbol combination {S ₁ ^S , S ₂ ^P } transmitted at the initial transmission time ( combining gain). That is, the transmission antenna for transmitting the symbol corresponding to the structural bit and the symbol corresponding to the parity bit may be interchanged according to the order of the retransmission period. The transmitter transmits the symbol combination {-S ₂ ^{S *} , S ₁ ^{P *} } at the third retransmission time.

7 is a block diagram showing a data transmission method in the STC according to another embodiment of the present invention.

Referring to FIG. 7, the transmitter includes three transmit antennas (first to third transmit antennas). Table 2 shows the symbol combinations transmitted at each transmission antenna. Hereinafter, a symbol transmitted from the first transmit antenna is called A, a symbol transmitted from the second transmit antenna is referred to as B, and a symbol transmitted from the third transmit antenna is referred to as C, and is transmitted from each transmit antenna at every transmission time. The symbol combination is represented as {A, B, C}.

First time to send First resend time Second retransmission time First transmitting antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^S Second transmitting antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S Third transmit antenna S ₃ ^P S ₃ ^{P *} S ₃ ^P

Referring to Table 2, it is assumed that the channel state of the first and second transmission antennas is relatively superior to that of the third transmission antenna from the initial transmission time to the second retransmission time. The transmitter transmits the symbol combination {S ₁ ^S , S ₂ ^S , S ₃ ^P } in consideration of the channel state of each transmitting antenna fed back from the receiver. If the receiver fails to receive the symbol combination {S ₁ ^S , S ₂ ^S , S ₃ ^P }, it informs the transmitter.

In response to the reception failure, the transmitter transmits a symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} , S ₃ ^{P *} } at the first retransmission time. That is, the symbol combinations transmitted by the first and second transmission antennas correspond to structural bits, which are space-time coded redundancy symbol combinations with respect to symbol combinations of previous transmission periods. On the other hand, the symbol transmitted from the third transmit antenna corresponds to a parity bit, which is a conjugate redundancy symbol combination. If the receiver fails to receive the symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} , S ₃ ^{P *} }, it informs the transmitter. During odd-numbered retransmissions, the same symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} , S ₃ ^{P *} } is transmitted.

In response to the reception failure, the transmitter transmits a symbol combination {S ₁ ^S , S ₂ ^S , S ₃ ^P } at a second retransmission time. That is, the symbol combination transmitted at the second retransmission time is the same as the symbol combination transmitted at the first transmission time. During even-numbered retransmissions, the same symbol combination {S ₁ ^S , S ₂ ^S , S ₃ ^P } is transmitted.

In this way, the transmitter considers the channel state information of each transmit antenna fed back from the receiver, and thus, a symbol combination corresponding to a structural bit through two transmit antennas having a relatively good channel state at the time of initial transmission {S ₁ ^S , S ₂ ^S } The symbol S ₃ ^P corresponding to the parity bit is transmitted through one transmitting antenna having a relatively inferior channel state. Meanwhile, a space time coded redundancy symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} } of symbols corresponding to structural bits is obtained through two transmitting antennas having a relatively good channel state at the first retransmission time. And transmits S ₃ ^{P *} , which is a conjugate redundancy symbol of a symbol corresponding to a parity bit, through one transmit antenna having a relatively inferior channel state.

8 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

Referring to FIG. 8, the transmitter includes three transmit antennas (first to third transmit antennas). Table 3 shows the symbol combinations transmitted at each transmission antenna.

First time to send First retransmission time Second retransmission time Third retransmission time First transmitting antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^P S ₁ ^{P *} Second transmitting antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S -S ₃ ^{S *} Third transmit antenna S ₃ ^P S ₃ ^{P *} S ₃ ^S S ₂ ^{S *}

Referring to Table 3, it is assumed that the channel state of the first and second transmission antennas is relatively superior to that of the third transmission antenna from the initial transmission time to the third retransmission time. The transmitter transmits symbols corresponding to parity bits in a third transmit antenna in which the channel state is relatively inferior when transmitting the spatial multiplexed symbols at the first transmission time, and the first and second channels having a relatively good channel state. The transmit antenna transmits a symbol corresponding to a structural bit.

Then, at the first retransmission time, the transmitter obtains retransmission gain for the structural bits by using orthogonality formed by the first and second transmit antennas having a relatively good channel condition, and then the second and third At the time of retransmission, the symbols corresponding to the parity bits are transmitted through the first and second transmission antennas having excellent channel conditions, thereby improving reliability of the parity bits. Three retransmissions, including the initial transmission period, are repeated one cycle.

9 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

Referring to FIG. 9, the transmitter includes four transmit antennas (first to fourth transmit antennas). Table 4 shows the symbol combinations transmitted at each transmission time in each of the transmitting antennas.

First time to send First resend time Second retransmission time First transmitting antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^S Second transmitting antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S Third transmit antenna S ₃ ^P -S ₄ ^{P *} S ₃ ^P Fourth transmitting antenna S ₄ ^P S ₃ ^{P *} S ₄ ^P

Referring to Table 4, it is assumed that the channel state of the first and second transmission antennas is relatively superior to that of the third and fourth transmission antennas from the initial transmission time to the second retransmission time.

In the initial transmission period, the transmitter transmits a symbol combination {S ₁ ^S , S ₂ ^S } corresponding to a structural bit through the first and second transmission antennas having a relatively good channel state in consideration of the channel state information. The symbol combination {S ₃ ^P , S ₄ ^P } corresponding to the parity bit is transmitted through the relatively inferior third and fourth transmit antennas.

At the first retransmission time, the transmitter transmits the symbol combination {Space time coded redundancy of the symbol combination {S ₁ ^S , S ₂ ^S } corresponding to the structural bit through the first and second transmit antennas { -S ₂ ^{S *} , S ₁ ^{S *} }, and symbol combination {-S which is space time coded redundancy of the symbol corresponding to the parity bit through the third and fourth transmit antennas Send ₄ ^{P *} , S ₃ ^{P *} }.

At the second retransmission time, the transmitter transmits the symbol combination {S ₁ ^S , S ₂ ^S } corresponding to the structural bits through the first and second transmit antennas, and corresponds to the parity bits through the third and fourth transmit antennas. Send symbol combination {S ₃ ^P , S ₄ ^P }.

At the third retransmission time, the same symbol combination as the first retransmission time is transmitted, and at the fourth retransmission time, the same symbol combination as the second retransmission time is transmitted. That is, at the odd retransmission time, the same symbol combination as the first retransmission time is transmitted, and at the even retransmission time, the same symbol combination is transmitted at the same time as the first retransmission time, and this is repeated sequentially each time. That is, two retransmissions including the initial transmission are repeated one cycle.

10 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

Referring to FIG. 10, the transmitter includes four transmit antennas (first to fourth transmit antennas). Table 5 shows the symbol combinations transmitted at each transmission antenna in each of the transmitting antennas.

First time to send First resend time Second retransmission time Third retransmission time First transmitting antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^P -S ₂ ^{P *} Second transmitting antenna S ₂ ^S S ₁ ^{S *} S ₂ ^P S ₁ ^{P *} Third transmit antenna S ₃ ^P -S ₄ ^{P *} S ₃ ^S -S ₄ ^{S *} Fourth transmitting antenna S ₄ ^P S ₃ ^{P *} S ₄ ^S S ₃ ^{S *}

Referring to Table 5, it is assumed that the channel states of the first and second transmission antennas are relatively superior to the channel states of the third and fourth transmission antennas from the initial transmission time to the third retransmission time. HARQ combining gain is improved through STC subpacket combining of the structural bits through the first and second transmit antennas having relatively good channel conditions in the initial transmission time and the first retransmission time. HARQ combining gain is improved by transmitting symbols corresponding to the parity bits through the first and second transmit antennas having a relatively good channel state at the second retransmission time and the third retransmission time.

So far, STC has been described as a multi-antenna technique, but other techniques such as space-frequency block code (SFBC), frequency-switched transmit diversity (FST), frequency-switched transmit diversity (FST), etc. Various techniques can be applied to the present invention. Hereinafter, an example in which a technique other than STC is applied to the present invention will be described.

In the case of a space-frequency block code (SFBC) for two transmit antennas, a symbol transmitted to two adjacent subcarriers and two transmit antennas may be given by Equation 1 below.

N _t1 ¹ is a symbol transmitted on the first subcarrier in the first transmit antenna, N _t1 ² is a symbol transmitted on the second subcarrier in the first transmit antenna, and N _t2 ¹ is a symbol transmitted on the first subcarrier in the second transmit antenna. , N _t2 ² is a symbol transmitted on the second subcarrier in the second transmit antenna. Where S ₁ is because the symbol corresponding to the structural bits S ₁ and S ₁ is ^S, S ₂ is because the symbol corresponding to the parity bits is S ₂ S ₂ ^P.

Equation 1 can be easily extended to a space-time block code (STBC) for two transmit antennas. For STBC, N _t1 ¹ is a symbol transmitted over the first timeslot at the first transmit antenna, N _t1 ² is a symbol transmitted over the second timeslot at the first transmit antenna, and N _t2 ¹ is the ^first at the second transmit antenna The symbol transmitted through the timeslot, N _t2 ² , becomes the symbol transmitted through the second timeslot in the second transmit antenna.

In the case of SFBC for the four transmit antennas can be given by the following equation (2).

Where S ₁ is because the symbol corresponding to the structural bits S ₁ and S ₁ is ^S, S ₂ is because the symbol corresponding to the parity bits is S ₂ S ₂ ^P. The present invention is not limited to the above-described example, and the technical spirit of the present invention can be applied to various numbers of transmission antennas and various SFBC techniques.

Frequency-switched transmit diversity (FSTD) for two transmit antennas may be given by Equation 3 below.

Here, N _t1 ¹ is a symbol transmitted on the first subcarrier in the first transmission antenna, N _t1 ² is a symbol transmitted on the second subcarrier in the first transmission antenna, and N _t2 ¹ is transmitted on the first subcarrier in the second transmission antenna. The symbol N _t2 ² is a symbol transmitted on the second subcarrier in the second transmit antenna. Where S ₁ is because the symbol corresponding to the structural bits S ₁ and S ₁ is ^S, S ₂ is because the symbol corresponding to the parity bits is S ₂ S ₂ ^P.

Frequency-switched transmit diversity (FSTD) for four transmit antennas may be given by Equation 4 below.

Here, N _ti ^j is a symbol transmitted on the i th transmit antenna and the j th subcarrier (i = 1, 2, 3, 4, j = 1, 2, 3, 4). Meanwhile, since S ₁ and S ₂ are symbols corresponding to structural bits, S ₁ is S ₁ ^S and S ₂ is S ₂ ^S. Since S ₃ and S ₄ are symbols corresponding to parity bits, S ₃ is S ₃ ^P and S ₄ is S ₄ ^P.

When SFBC and FSTD are combined for four transmission antennas, the following Equation 5 may be given.

Here, N _ti ^j is a symbol transmitted on the i th transmit antenna and the j th subcarrier (i = 1, 2, 3, 4, j = 1, 2, 3, 4). Meanwhile, since S ₁ and S ₂ are symbols corresponding to structural bits, S ₁ is S ₁ ^S and S ₂ is S ₂ ^S. Since S ₃ and S ₄ are symbols corresponding to parity bits, S ₃ is S ₃ ^P and S ₄ is S ₄ ^P.

11 is a block diagram illustrating a terminal according to an example of the present invention.

Referring to FIG. 11, like the base station 20, the terminal 10 includes a control unit 110, a data processor 120, a transmit / receiver circuitry 130, and multiple antennas. 140, and user interface circuitry 150.

The transmission / reception circuit 130 transmits a radio frequency signal transmitted by dividing a symbol corresponding to a structural bit and a symbol corresponding to a parity bit from one or more base stations 20 through the multi-antenna 140. Receive. Preferably, a low noise amplifier and a filter (not shown in FIG. 11) cooperate with each other to amplify after removing broadband interference from the signal to be processed. Digitization circuitry, not shown in FIG. 11, digitizes the received signal into a baseband signal that is one or more digital streams.

The data processor 120 processes the digitized received signal and extracts information or data bits contained in the received signal. The processing includes demodulation, decoding, and error correction operation, which will be described later. The data processor 120 is generally implemented by one or more Digital Signal Processors (DSPs) and Application Specific Integrated Circuits (ASICs).

In order to transmit a signal, the data processor 120 receives digitized data representing voice data, data, or control information to be encoded from the controller 110 for transmission. The encoded data is input to the transceiver circuit 130 and used by the modulator to modulate a carrier corresponding to a suitable transmission frequency. A power amplifier (not shown) amplifies the modulated carrier to a level suitable for transmission and carries the modulated carrier to the multiple antenna 140. The multiple antenna 140 and the transceiver circuit 130 provide spatial diversity.

Meanwhile, the terminal 10 may receive and process all signals by any multi-antenna technique in MIMO. For example, the transceiver circuit 130 may be an MMSE receiver circuit.

All of the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiments, and the present invention will include all embodiments within the scope of the following claims.

1 is a block diagram illustrating a wireless communication system.

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

3 is a block diagram illustrating an example of a data transmission method in STC.

4 is a block diagram illustrating another example of a data transmission method in STC.

5 is a block diagram illustrating a data transmission method in an STC according to an embodiment of the present invention.

6 is a block diagram illustrating a data transmission method in an STC according to another embodiment of the present invention.

7 is a block diagram showing a data transmission method in the STC according to another embodiment of the present invention.

8 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

9 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

10 is a block diagram showing a data transmission method in an STC according to another embodiment of the present invention.

11 is a block diagram illustrating a terminal according to an example of the present invention.

Claims (8)

In the data transmission method using multiple antennas, Transmitting a first symbol corresponding to the structural bit from a code block including a structural bit and a parity bit through a first transmitting antenna; And And transmitting a symbol corresponding to the structural bit and transmitting a second symbol corresponding to the parity bit through a second transmission antenna. The method of claim 1, And the structural bits and the parity bits are space-time coded. The method of claim 1, Receiving a retransmission request for the codeblock; And Retransmitting the first symbol through the first transmit antenna and retransmitting the second symbol through the first transmit antenna. The method of claim 1, Receiving a retransmission request for the codeblock; And Retransmitting the first symbol through the second transmit antenna and retransmitting the second symbol through the second transmit antenna. The method of claim 4, wherein The channel state of the first transmit antenna is relatively superior to the channel state of the second transmit antenna. The method of claim 5, wherein The channel state is determined based on a signal-to-noise ratio (SNR). In the data transmission method using multiple antennas, Dividing the code block into structural bits and parity bits; Transmitting the structural bits via a first transmit antenna; Transmitting the parity bits via a second transmit antenna; Receiving a retransmission request for the codeblock; And And retransmitting the structural bits and the parity bits through the first and second transmit antennas. The method of claim 7, wherein Wherein the structural bits and the parity bits are retransmitted by HARQ.

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