KR101486080B1 - Method of Data Transmission using Multiple Antenna - Google Patents

Abstract

According to an aspect of the present invention, there is provided a data transmission method using multiple antennas. The method includes transmitting a first symbol corresponding to the structured bit among code blocks divided by a structured bit and a parity bit through a first transmission antenna, and transmitting a symbol corresponding to the structured bit, And transmitting the corresponding second symbol through the second transmission antenna. The data is divided into a structural bit and a parity bit, differentiated according to the channel state, and transmitted through different transmission antennas, thereby realizing an easy implementation and further improved data transmission performance.

Multiple antenna, STC, space-time code, code block, systematic, parity, HARQ

Description

TECHNICAL FIELD [0001] The present invention relates to a data transmission method using multiple antennas,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a data transmission method using multiple antennas.

There has been an explosion of demand for wireless data services in recent years. And the evolution from wireless voice services to wireless data services is demanding a gradual increase in wireless capacity. This demand motivates wireless service providers and wireless equipment manufacturers to seek to improve the data rate of wireless systems and to engage in vast research.

A wireless channel has many problems such as path loss, shadowing, fading, noise, limited bandwidth, terminal power limit, and interference between different users. ≪ / RTI > These limitations make the wireless channel similar to a narrow pipe that hampers the fast flow of data and make 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 mobility issues associated with resource allocation, rapidly changing physical channels, portability, and the provision of security and privacy. Design.

When the transmission channel experiences a deep fading, it is difficult for the receiver to determine the transmitted signal if another version or replica of the transmitted signal is not separately transmitted. 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 wireless channels. This diversity can maximize data transmission capacity or data transmission reliability. A system that implements diversity using multiple transmit antennas and multiple receive antennas is referred to as a Multiple Input Multiple Output (MIMO) system. The MIMO system is also referred to as a multiple antenna system.

Thus, a transmitter has N transmit antennas, and a receiver has M receive antennas. Space-Time Coding (STC) can control which data is transmitted from each of the N transmit antennas. The transmitter's space-time encoding function processes the data to be transmitted and generates unique information to be transmitted on the N transmit antennas. Each of the M receive antennas receives signals transmitted from each of the N transmit antennas. The receiver's space-time decoding function combines the information sent from the N transmit antennas to generate data.

STC can be typically 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). The scheme of another embodiment is to transmit different data from different N transmit antennas, and redundancy in the STTD scheme is avoided. This is called Vertical-Bell Laboratories Layered Space Time (V-BLAST) technique.

The STTD scheme is effective for increasing the diversity gain, but it is inefficient because duplication is essential. The V-BLAST scheme improves system throughput for systems that are capable of sufficient diversity. If a certain threshold diversity is achieved in the BLAST system, the data rate increases theoretically in proportion to the number of transmit and receive antennas, while the additional spatial diversity in the STTD system does not significantly affect the data rate.

A hybrid automatic repeat request (HARQ) scheme is used as an error compensation scheme for ensuring reliability of communication. The HARQ system checks whether data received by the physical layer includes an error that can not be decoded and requests retransmission when an error occurs, thereby improving performance. In the HARQ scheme, if an error is not detected in the received data, the receiver transmits an ACK (acknowledgment) signal as a response signal and notifies the transmitter of the success of reception. When an error is detected in the received data, the receiver sends a negative acknowledgment (NACK) signal to the transmitter to notify the error detection. The transmitter can retransmit the data when the NACK signal is received.

The mode of HARQ can be divided into chase combining and incremental redundancy (IR). Chase combining is a method of obtaining a signal-to-noise ratio (SNR) gain by combining error-detected data with retransmitted data without discarding the data. The IR is a method of incrementally transmitting additional redundant information to retransmitted data to reduce the burden of retransmission and obtain coding gain.

Much research has been done by those skilled in the art about HARQ. However, HARQ has not been studied in the transmission using multiple antennas. This is due in part to the fact that signals transmitted from different antennas in the space-time channel overlap each other, making it difficult to improve the transmitted signal with HARQ. On the other hand, even if HARQ can be used, the orthogonality of the equal channel may be broken due to the time latency between the initial transmission and the retransmission of the data packet, and performance degradation may be caused. From this point of view, there is a need for a data transmission method using multiple antennas that can improve data retransmission performance.

SUMMARY OF THE INVENTION The present invention provides a method of transmitting data using multiple antennas.

According to an aspect of the present invention, there is provided a data transmission method using multiple antennas. Transmitting a first symbol corresponding to the structured bit among a code block composed of a systematic bit and a parity bit through a first transmission antenna and transmitting a symbol corresponding to the structured bit, And transmitting a second symbol corresponding to the parity bit through a second transmission antenna.

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

In a multi-antenna system, when data is transmitted using HARQ, data is divided into structural bits and parity bits, differentiated according to channel conditions, and transmitted through different transmission antennas, thereby achieving an improved implementation of data transmission performance .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals designate like elements throughout the specification.

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

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

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 the downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In the 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 utilizes the orthogonality property between IFFT (inverse fast Fourier transform) and FFT (fast Fourier transform). In the transmitter, data is transmitted by performing IFFT. The receiver performs an 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 a diagram illustrating an example of processing of an information block for performing HARQ.

Referring to FIG. 2, all or a part of an information block is sent to a transport block for transmission to a physical layer, and a CRC (error detection code) is added to one transport block (CRC attachment) . The information block may be called PDU (Protocol Data Unit) of MAC (Medium Access Control). The MAC PDU is a data unit transmitted from the MAC layer, which is the upper layer, to the physical layer when a layer for performing HARQ is referred to as a physical layer.

The transport block to which the CRC is added is divided into a code block segmentation for channel coding. The divided blocks are called code blocks. The code block is a data block of a predetermined size for performing channel encoding. The code blocks may have the same size, and the plurality of code blocks may have different sizes.

An encoder performs channel coding on a code block and outputs coded bits. The encoder can apply turbo code, one of the error correction codes. The turbo code generates a systematic bit and a parity bit on a bit-by-bit basis from an input code block. Here, it is assumed that a systematic block S and two parity blocks P1 and P2 are output assuming a 1/3 code rate. A structured block is a set of structured bits, and a parity block is a set of parity bits. The error correction code is not limited to the turbo code, and the technical idea of the present invention can be applied to low density parity check code (LDPC) or other convolution codes.

One HARQ function is performed in units of transport blocks. The HARQ processor performs an HARQ mode (chase combining or IR) and an HARQ method (adaptive HARQ or non-adaptive HARQ) according to a retransmission environment in order to retransmit a packet in which an error has occurred.

The channel interleaver interleaves the channel-encoded code blocks to reduce the effect of burst errors that occur as they are transmitted on the wireless channel. A physical resource mapper converts the interleaved coded bits into data symbols and maps the coded bits to subburs of the data area. The channel interleaver may perform interleaving for each of the structural block S and the two parity blocks P1 and P2.

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

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

For convenience of explanation, retransmission will be interpreted on a symbol-by-symbol basis. However, one of ordinary skill in the art will recognize that retransmission is retransmission of a corresponding group of symbols to all or a portion of a transmitted data packet. It is assumed that the receiver includes a STC decoder, which provides BLAST decoding to decode the transmitted symbols at each transmission time.

And informs the transmitter of the failure (NACK) if the receiver fails to decode the symbols S ₁ and S ₂ transmitted at the initial transmission time. 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 time. Here, S ₁ ^* and S ₂ ^* are complex conjugates of S ₁ and S ₂ , respectively.

At this time, bits corresponding to the symbols S ₁ and S ₂ of the first transmission time and bits corresponding to the symbols S ₂ ^* and S ₁ of the first retransmission time are transmitted to the receiver through Chase Combiner) to recover the original data by obtaining gain in terms of the received energy of the original data or the signal-to-noise ratio (SNR).

If the receiver fails to decode the symbols S ₁ and S ₂ transmitted at the initial transmission time also by the symbols -S ₂ ^* and S ₁ received during the first retransmission time, the receiver notifies the retransmission of the code block Request from the transmitter. The transmitter that receives the retransmission request responds by transmitting symbols S ₁ and S ₂ through the first transmission antenna and the second transmission antenna, respectively, during the second retransmission time. As described above, the symbols S ₂ ^* and S ₁ are transmitted during the odd-numbered retransmission time, and the symbols S ₁ and S ₂ are transmitted during the retransmission time corresponding to the even-numbered retransmission time.

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

4, symbols S ₁ , S ₂ , S ₃ , -S ₂ ^* , S ₃ ^* , and so on include three transmit antennas (first to third transmit antennas) Lt; RTI ID = 0.0 > Tx < / RTI > transmit antennas. During the initial transmission period, a symbol S ₁ is transmitted on the first transmission antenna, while a symbol S ₂ is transmitted on the second transmission antenna, while a symbol S ₃ is transmitted on the third transmission antenna.

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

As described above, during the retransmission period corresponding to the odd-numbered bits, the symbols S _{1 ,} S ₂ And S ₃ , and during the retransmission period corresponding to the even-numbered bits, symbols -S ₂ ^* , S ₁ And S ₃ ^* . Space-time coded redundancy designed to have orthogonality is retransmitted in the first and second transmission antennas, and congestion redundancy is retransmitted in the third transmission antenna.

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

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

The unit of data to be transmitted or retransmitted can be interpreted in units of a structural bit and a parity bit, but will be interpreted on a symbol-by-symbol basis for convenience of explanation. However, one of ordinary skill in the art will recognize that retransmission is retransmission of a corresponding group of symbols to all or a portion of a transmitted data packet.

During the initial transmission period, a symbol S ₁ ^S corresponding to a structured bit is transmitted from the first transmission antenna, and at the same time, a symbol S ₂ ^P corresponding to a parity bit is transmitted from the second transmission antenna. And informs the transmitter of the failure if the receiver fails to decode symbols S ₁ ^S and S ₂ ^P transmitted at the initial transmission time. 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 *} through the first transmission antenna and the second transmission antenna, respectively, during the first retransmission time.

If the receiver fails to decode the symbols S ₁ ^S and S ₂ ^P transmitted at the initial transmission time also by the symbols -S ₂ ^{P *} and S ₁ ^{S *} received during the first retransmission time, . In response, the transmitter responds by retransmitting symbols S ₁ ^S and S ₂ ^P through the first transmit antenna and the second transmit antenna, respectively, during a second retransmission time. S ₂ ^{P *} and S ₁ ^{S *} are transmitted during the retransmission period corresponding to the odd number and S ₁ ^S and S ₂ ^P are transmitted during the retransmission period corresponding to the even number, Can be increased.

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

In this manner, the symbol corresponding to the structured bit and the symbol corresponding to the parity bit are separated and transmitted from different antennas, thereby improving the HARQ performance in the STC.

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

Referring to FIG. 6, the transmitter includes two transmit antennas (first and second transmit antennas). Table 1 shows symbol combinations transmitted at each transmission timing in each of the transmission antennas. Let A be the symbol transmitted from the first transmission antenna and B be the symbol transmitted from the second transmission antenna. Let {A, B} represent symbol combinations transmitted from the respective transmission antennas at each transmission time.

First transmission time The first retransmission time Second Retransmission Timing Third Retransmission Timing The first transmission antenna S ₁ ^S -S ₂ ^{P *} S ₁ ^P -S ₂ ^{S *} The second transmission 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 Tx antenna is relatively good from the first transmission time to the third retransmission time. At the initial transmission time, 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 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. And transmits a symbol corresponding to a parity bit through a first transmission antenna having a relatively good channel state as compared with the symbol combination {S ₁ ^S , S ₂ ^P } transmitted at the initial transmission time, combining gain. That is, the symbols corresponding to the structured bits and the transmit antennas transmitting the symbols corresponding to the parity bits may be exchanged 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 illustrating a data transmission method in an STC according to another example of the present invention.

Referring to FIG. 7, the transmitter includes three transmission antennas (first through third transmission antennas). Table 2 shows symbol combinations transmitted at each transmission timing in each of the transmission antennas. Hereinafter, a symbol transmitted through the first transmission antenna will be referred to as A, a symbol transmitted through the second transmission antenna will be referred to as B, and a symbol transmitted through the third transmission antenna will be referred to as C, Symbol combinations are denoted by {A, B, C}.

First transmission time The first retransmission time Second Retransmission Timing The first transmission antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^S The second transmission antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S Third transmission antenna S ₃ ^P S ₃ ^{P *} S ₃ ^P

Referring to Table 2, it is assumed that the channel states of the first and second transmission antennas are relatively superior to the channel state 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 } considering the channel state of each transmission 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 notifies the transmitter thereof.

For 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 combination of symbols transmitted in the first and second transmission antennas corresponds to a structured bit, and is a space-time coded redundancy symbol combination for a symbol combination at a previous transmission time. On the other hand, the symbol transmitted from the third transmission antenna corresponds to a parity bit, and 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. At the odd-numbered retransmission times, the same symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} , S ₃ ^{P *} } is transmitted.

For the reception failure, the transmitter transmits a symbol combination {S ₁ ^S , S ₂ ^S , S ₃ ^P } at the second retransmission time. That is, the symbol combination transmitted at the second retransmission time is the same as the symbol combination transmitted at the initial transmission time. S ₁ ^S , S ₂ ^S , S ₃ ^P }, which are the same symbol combination, are transmitted at even-numbered retransmission times.

In this way, considering the channel state information for each transmission antenna fed back from the receiver, the transmitter transmits symbol combinations {S ₁ ^S , S ₂ ^S } corresponding to the structured bits through the two transmission antennas, And transmits a symbol S ₃ ^P corresponding to a parity bit through one transmit antenna with a relatively inferior channel state. Meanwhile, a space time coded redundancy symbol combination {-S ₂ ^{S *} , S ₁ ^{S *} } of the symbols corresponding to the structured bits is transmitted through the two transmission antennas having relatively good channel states 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 transmission antenna with a relatively inferior channel state.

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

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

First transmission time The first retransmission time Second Retransmission Timing Third Retransmission Timing The first transmission antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^P S ₁ ^{P *} The second transmission antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S -S ₃ ^{S *} Third transmission antenna S ₃ ^P S ₃ ^{P *} S ₃ ^S S ₂ ^{S *}

Referring to Table 3, it is assumed that the channel states of the first and second transmission antennas are relatively superior to the channel state of the third transmission antenna from the initial transmission time to the third retransmission time. The transmitter transmits symbols corresponding to the parity bits in the third transmission antenna having the relatively inferior channel state when transmitting the spatially multiplexed symbols at the initial transmission time and transmits the symbols corresponding to the first and second And transmits symbols corresponding to the structured bits in the transmission antenna.

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

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

Referring to FIG. 9, the transmitter includes four transmission antennas (first through fourth transmission antennas). Table 4 shows symbol combinations transmitted at each transmission timing in each transmission antenna.

First transmission time The first retransmission time Second Retransmission Timing The first transmission antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^S The second transmission antenna S ₂ ^S S ₁ ^{S *} S ₂ ^S Third transmission antenna S ₃ ^P -S ₄ ^{P *} S ₃ ^P Fourth transmission antenna S ₄ ^P S ₃ ^{P *} S ₄ ^P

Referring to Table 4, 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 first transmission time to the second retransmission time.

At the initial transmission time, the transmitter transmits a symbol combination {S ₁ ^S , S ₂ ^S } corresponding to the structured bits through the first and second transmission antennas with relatively good channel states in consideration of the channel state information, And transmits symbol combinations {S ₃ ^P , S ₄ ^P } corresponding to parity bits through relatively inferior third and fourth transmit antennas.

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

At the second retransmission time, the transmitter transmits a symbol combination {S ₁ ^S , S ₂ ^S } corresponding to the structured bits through the first and second transmission antennas, and transmits a symbol combination {S ₁ ^S , S ₂ ^S } Symbol combination {S ₃ ^P , S ₄ ^P }.

The same symbol combination as the first retransmission time is transmitted at the third retransmission time, and the same symbol combination as the second retransmission time is transmitted at the fourth retransmission time. That is, in the odd retransmission time, the same symbol combination as the first retransmission time is transmitted, and in the even-numbered retransmission time, the same symbol combination as the first transmission time is transmitted. That is, two retransmissions including the initial transmission are repeated one cycle at a time.

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

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

First transmission time The first retransmission time Second Retransmission Timing Third Retransmission Timing The first transmission antenna S ₁ ^S -S ₂ ^{S *} S ₁ ^P -S ₂ ^{P *} The second transmission antenna S ₂ ^S S ₁ ^{S *} S ₂ ^P S ₁ ^{P *} Third transmission antenna S ₃ ^P -S ₄ ^{P *} S ₃ ^S -S ₄ ^{S *} Fourth transmission 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 structured bits through the first and second transmission antennas with a relatively good channel state at the initial transmission time and the first retransmission time. HARQ combining gain is improved by transmitting symbols corresponding to a parity bit through first and second transmission antennas having a relatively good channel state at a second retransmission time and a third retransmission time.

Although STC has been mainly described as a multi-antenna technique, other techniques such as space-frequency block code (SFBC), frequency-switched transmit diversity (FSTD), and frequency-switched transmit diversity 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, symbols transmitted on two adjacent subcarriers and two transmit antennas can be given by Equation (1).

N _t1 ¹ is a symbol transmitted through the first sub-carrier in the first transmission antenna, N _t1 ² is a symbol transmitted through the second sub-carrier in the first transmission antenna, N _t2 ¹ is a symbol transmitted through the first sub- And N _t2 ² is a symbol transmitted through the second sub-carrier in the second transmission 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 transmission antennas. In STBC, N _t1 ¹ is a symbol transmitted through a first time slot in a first transmission antenna, N _t1 ² is a symbol transmitted through a second time slot in a first transmission antenna, N _t2 ¹ is a symbol transmitted through a first transmission antenna, A symbol transmitted through a time slot, and N _t2 ² is a symbol transmitted through a second time slot in a second transmission antenna.

In the case of the SFBC for the four transmit antennas, the following Equation 2 can be given.

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 technical idea of the present invention can be applied to various SFBC techniques and the number of various transmission antennas.

The frequency-switched transmit diversity (FSTD) for the two transmit antennas can be given by Equation 3 below.

Here, N _t1 ¹ is a symbol transmitted through the first sub-carrier in the first transmission antenna, N _t1 ² is a symbol transmitted through the second sub-carrier in the first transmission antenna, N _t2 ¹ is transmitted through the first sub- And N _t2 ² is a symbol transmitted through the second sub-carrier in the second transmission 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.

The frequency-switched transmit diversity (FSTD) for the four transmit antennas can be given by Equation (4).

Here, N _ti ^j is a symbol transmitted to the i-th transmit antenna and the j-th subcarrier (i = 1, 2, 3, 4, j = 1, 2, 3, 4). Since S ₁ and S ₂ are symbols corresponding to the structured 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.

SFBC and FSTD are combined for four transmit antennas, the following Equation 5 can be given.

Here, N _ti ^j is a symbol transmitted to the i-th transmit antenna and the j-th subcarrier (i = 1, 2, 3, 4, j = 1, 2, 3, 4). Since S ₁ and S ₂ are symbols corresponding to the structured 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 exemplary embodiment of the present invention.

11, the terminal 10 includes a control unit 110, a data processor 120, a transmit / receiver circuitry 130, multiple antennas , 140, and a user interface circuitry (150).

The transmission / reception circuit 130 transmits a radio frequency signal, which is divided into a symbol corresponding to a structured bit and a symbol corresponding to a parity bit, from one or more base stations 20 through the multiple antennas 140 . Preferably, a low noise amplifier and filter (not shown in FIG. 11) cooperate with each other to remove and then amplify broadband interference from the signal to be processed. A digitization circuitry, not shown in FIG. 11, digitizes the received signal into a baseband signal, which is one or more digital streams.

The data processing unit 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 operations, which will be described later. The data processing unit 120 is generally implemented by one or more digital signal processors (DSPs) and application specific integrated circuits (ASICs).

For transmission of a signal, the data processing unit 120 receives digitized data representing speech data, data, or control information to be encoded from the control unit 110 for transmission. The coded data is input to the transmission / reception circuit 130, and is used by a 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 conveys the modulated carrier to the multiple antenna 140. [ The multiple antennas 140 and the transceiver circuit 130 provide spatial diversity.

Meanwhile, the terminal 10 can receive and process all signals of any multi-antenna scheme in MIMO. For example, the transmission / reception circuit 130 may be an MMSE reception circuit.

All of the above-described 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 or the like coded to perform the above functions. The design, development and implementation of the above code will be apparent to those skilled in the art based on the description of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, it is intended that the present invention covers all embodiments falling within the scope of the following claims, rather than being limited to the above-described embodiments.

1 is a block diagram illustrating a wireless communication system.

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

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

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

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

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

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

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

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

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

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

Claims (8)

A method of transmitting data using a plurality of antennas, Mapping a parity symbol including a structured symbol including a structured bit and a parity bit to each of the plurality of antennas based on first channel state information for each of the plurality of antennas; When a primary retransmission of the structured symbol and the parity symbol is requested from a receiver, based on second channel state information for each of the plurality of antennas, the complex conjugate of the structured symbol and the complex conjugate of the parity symbol are divided into a plurality of A second mapping to each of the antennas to perform a primary retransmission; Wherein when the secondary retransmission of the structured symbol and the parity symbol is requested from the receiver after the primary retransmission, the structured symbol and the parity symbol are transmitted on the basis of the third channel state information for each of the plurality of antennas, A third mapping and third retransmitting to each of the plurality of antennas; And Wherein when the third retransmission of the structured symbol and the parity symbol is requested from the receiver after the second retransmission, the complex conjugate of the structured symbol and the complex conjugate of the structured symbol based on the fourth channel state information for each of the plurality of antennas, Mapping the complex conjugate of the parity symbol to each of the plurality of antennas, and performing a third-order retransmission, Wherein the first mapping maps the structured symbols to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the first channel state information, maps the parity symbols to the remaining antennas, Wherein the second mapping maps the complex conjugate symbol of the parity symbol to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the second channel state information, Map conjugate complex symbols, The third mapping maps the parity symbols to at least one antenna having a relatively good channel state among the plurality of antennas considering the third channel state information, maps the structured symbols to the remaining antennas, The fourth mapping maps the complex conjugate symbol of the structured symbol to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the fourth channel state information, A method of transmitting data using a plurality of antennas mapping complex conjugate symbols. The method according to claim 1, Wherein the second channel state information is determined by the receiver based on the structural symbol and the parity symbol transmitted based on the first mapping, Wherein the third channel state information is determined by the receiver based on the complex conjugate of the structural symbol transmitted based on the second mapping and the complex conjugate of the parity symbol, Wherein the fourth channel state information is determined based on the structural symbols and the parity symbols transmitted based on the third mapping. A transmitter for transmitting data using a plurality of antennas, the transmitter comprising a processor, The processor first maps a structural symbol including a structured bit and a parity symbol including a parity bit to each of the plurality of antennas based on first channel state information for each of the plurality of antennas, When a primary retransmission of the structured symbol and the parity symbol is requested from a receiver, based on second channel state information for each of the plurality of antennas, the complex conjugate of the structured symbol and the complex conjugate of the parity symbol are divided into a plurality of The first mapping is performed for each of the antennas, Wherein when the secondary retransmission of the structured symbol and the parity symbol is requested from the receiver after the primary retransmission, the structured symbol and the parity symbol are transmitted on the basis of the third channel state information for each of the plurality of antennas, Third mapping is performed to each of the plurality of antennas to perform secondary retransmission, Wherein when the third retransmission of the structured symbol and the parity symbol is requested from the receiver after the second retransmission, the complex conjugate of the structured symbol and the complex conjugate of the structured symbol based on the fourth channel state information for each of the plurality of antennas, And a third mapping unit for mapping the complex conjugate of the parity symbol to each of the plurality of antennas to perform a third order retransmission, Wherein the first mapping maps the structured symbols to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the first channel state information, maps the parity symbols to the remaining antennas, Wherein the second mapping maps the complex conjugate symbol of the parity symbol to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the second channel state information, Map conjugate complex symbols, The third mapping maps the parity symbols to at least one antenna having a relatively good channel state among the plurality of antennas considering the third channel state information, maps the structured symbols to the remaining antennas, The fourth mapping maps the complex conjugate symbol of the structured symbol to at least one antenna having a relatively good channel state among the plurality of antennas in consideration of the fourth channel state information, A transmitter that maps complex conjugate symbols. The method of claim 3, Wherein the second channel state information is determined by the receiver based on the structural symbol and the parity symbol transmitted based on the first mapping, Wherein the third channel state information is determined by the receiver based on the complex conjugate of the structural symbol transmitted based on the second mapping and the complex conjugate of the parity symbol, And the fourth channel state information is determined based on the structural symbol and the parity symbol transmitted based on the third mapping. delete delete delete delete

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