KR20100103315A - Method and apparatus for transmitting/receiving feedback inforamtion in a communication system using a plurality of antennas - Google Patents

Abstract

PURPOSE: A method and a device for transmitting/receiving feedback information in a communication system using a plurality of antennas are provided to use a common feedback channel way and can reduce the feedback frequency resource used in a multicast transmission, thereby largely improving the performance according to the increase of the number of user terminal in corresponding cell. CONSTITUTION: Data packet is received from a base station(210) through a down link multicast transmission channel. The data packet is decoded and whether decoding of the data packet is successful or not is checked. If the decoding of the data packet is failed after checking the result, it generates NACK signal which shows failure of decoding the data packet by using series of the same numbers with the antenna numbers. The NACK signal is transmitted to the base station through a common feedback channel. The generated series each has orthogonality between each other, and comprises a sequence signal.

Description

TECHNICAL AND APPARATUS FOR TRANSMITTING / RECEIVING FEEDBACK INFORAMTION IN A COMMUNICATION SYSTEM USING A PLURALITY OF ANTENNAS

The present invention relates to a method and apparatus for transmitting and receiving feedback information in a communication system using a plurality of antennas.

Recently, as a demand for a service for transmitting the same multimedia data packet to a plurality of user terminals increases, communication broadcast convergence technologies and services bringing advantages and ameliorating disadvantages of communication networks and broadcasting networks have been attracting attention. Techniques for improving the efficiency of broadcasting and multicast transmission in the communication network include multimedia broadcast and multicast service (MBMS), which is being standardized in 3rd generation partnership project (3GPP), and MBS (standardization, which is being standardized, in IEEE 802.16). multicast and broadcast service).

The MBMS is a service for transmitting the same data packet to multiple user terminals at the same time. That is, multiple user terminals using MBMS simultaneously receive the same data packet through one link. This MBMS scheme is similar to the CBS (cell broadcast service) scheme. However, the CBS scheme is a low-speed message-based service, whereas the MBMS scheme is a service aimed at high-speed multimedia data packet transmission based on IP multicast transmission. Therefore, the MBMS scheme can increase the efficiency of resource usage, and the user terminal using the MBMS scheme can use multimedia services at low cost.

The MBMS scheme is divided into a multi-cell and a single-cell basis.

First, in the multi-cell based MBMS scheme, a plurality of base stations transmit the same data packet based on a single frequency network (SFN). Thereafter, the user terminals may soft combine the data packets received from the plurality of base stations to obtain a macro diversity gain. Due to this feature, the multi-cell based MBMS scheme is advantageous for data type transmission of a broadcast type using only downlink. On the other hand, it is difficult to guarantee the quality of service (QoS) for each user terminal. Therefore, the multi-cell based MBMS scheme is not well used for transmitting different multicast data packets for each region.

On the other hand, a single cell based MBMS scheme that can compensate for the shortcomings of the multi-cell based MBMS scheme, that is, guarantee QoS of individual user terminals, has emerged. The single cell based MBMS scheme guarantees QoS of each of the user terminals included in the multicast group through application of Hybrid Automatic Retransmit ReQuest (H-ARQ). To this end, the base station should receive feedback information for each user terminal included in the multicast group. The feedback information is an ACK / NACK signal indicating whether decoding of a multicast data packet from the base station is successful. Accordingly, a feedback channel is required for user terminals included in the multicast group to transmit the feedback information to the base station.

As a method of allocating a feedback channel, an individual allocation method for allocating an ACK / NACK channel for unicast transmission for each terminal and on-off keying (OOK) are called OOK. A common feedback channel method using a modulation scheme may be considered. In the common feedback channel scheme, user terminals in a group share one feedback channel. Therefore, no matter how many user terminals increase, the required feedback channel resources do not increase.

In general, since the ACK signal is determined to be an off signal of the NACK signal in the OOK method, it is not transmitted separately.

The base station receiving the feedback information, at least one of the user terminals belonging to the multicast group other than the success of decoding the multicast data packet for each user terminal does not succeed in decoding the data packet. Only concern. That is, the base station needs to know whether there is at least one user terminal that has transmitted the NACK signal in the multicast group. Therefore, each user terminal does not transmit an ACK signal when decoding succeeds, but only a NACK signal when decoding fails. In this case, the base station synthesizes NACK signals received from the user terminals through the common feedback channel by using a OOK modulation scheme. The signal synthesized through the OOK modulation technique is used to determine the existence of a user terminal that transmits a NACK signal using an energy detection technique.

As described above, the common feedback channel scheme does not allocate a feedback channel for each user terminal, and by using one common feedback channel using the OOK modulation scheme, no additional resources are generated as the number of user terminals increases. In addition, as the number of user terminals increases, the energy of the synthesized signal increases, so that the miss detection of the signal decreases. Accordingly, the common feedback channel scheme is more efficient than the individual allocation technique as the number of user terminals in the multicast group increases.

When a user terminal having a plurality of antennas is used in a common feedback channel scheme, the number of paths according to the plurality of antennas increases. As a result, the independence of the channel response may be increased, resulting in performance improvement.

However, the degree of performance improvement is insignificant. Therefore, there is a need for a common feedback channel that can result in greater performance when multiple antennas are applied.

The present invention proposes a method and apparatus for transmitting and receiving feedback information in a communication system using a plurality of antennas.

The present invention proposes a method and apparatus for generating feedback information of a user terminal using a plurality of antennas in the form of a sequence having orthogonal characteristics for each of the plurality of antennas.

The present invention provides a method and apparatus for generating feedback information of a user terminal using a plurality of antennas in a sequence form having an orthogonal characteristic for each of the plurality of antennas and transmitting the sequence form feedback information through a common feedback channel. do.

According to an aspect of the present invention, there is provided a method for transmitting feedback information by a user terminal using at least two antennas in a communication system, the method comprising: receiving a data packet from a base station through a downlink multicast transmission channel; Decoding the data packet, checking whether the data packet has been successfully decoded; and when the decoding of the data packet fails as a result of the checking, the number of NACK signals indicating failure of decoding of the data packet is equal to the number of antennas. And generating the NACK signal to the base station through a common feedback channel. Each of the generated sequences has orthogonality to each other and includes a sequence signal. .

According to another aspect of the present invention, there is provided a method of transmitting data packets to a plurality of user terminals through a downlink multicast transmission channel, and at least one user terminal receiving the data packets among the user terminals. Receiving feedback information indicating whether the decoding of the data packet is successful through a common feedback channel, and detecting a sequence signal corresponding to each of at least two antennas included in the at least one user terminal from the feedback information. And calculating a total energy of the detected sequence signals, comparing the total energy with a threshold, and when the total energy exceeds the threshold as a result of the comparison, the feedback information is a NACK signal. And the feedback information is the same as that of the antennas. And a number of sequences, each of which is orthogonal to each other and comprises a sequence signal.

An apparatus according to an embodiment of the present invention is a device for transmitting feedback information in a communication system including a user terminal using at least two antennas for transmitting feedback information, and transmitting from a base station through a downlink multicast transmission channel. Receiving a decoded data packet, decoding the data packet, confirming whether the decoding of the data packet is successful, and if the decoding of the data packet fails as a result of the checking, the NACK signal indicating that the decoding of the data packet has failed. A user terminal generating using the same number of antennas as the number of antennas and transmitting the NACK signal to the base station through a common feedback channel; Each of the generated sequences is orthogonal to each other and includes a sequence signal.

Another apparatus according to an embodiment of the present invention, in the apparatus for receiving feedback information in a communication system, transmits a data packet to a plurality of user terminals through a downlink multicast transmission channel, and the data among the user terminals. Receive feedback information indicating whether the decoding of the data packet is successful from the at least one user terminal receiving the packet through a common feedback channel, each of the at least two antennas provided by the at least one user terminal from the feedback information Detects a sequence signal corresponding to a; calculates total energy of the detected sequence signals; compares the total energy with a threshold; and when the total energy exceeds the threshold as a result of the comparison, the feedback information A base station for determining that is a NACK signal; The feedback information includes the same number of sequences as the antennas, each of which is orthogonal to each other and includes a sequence signal.

A base station according to an embodiment of the present invention, in a base station receiving feedback information in a communication system, transmits a data packet to a plurality of user terminals through a downlink multicast transmission channel through a common feedback channel, and the user terminal Receiving feedback information indicating whether the decoding of the data packet is successful from at least one user terminal having received the data packet, and from each of the at least two antennas included in the at least one user terminal from the feedback information After detecting a corresponding sequence signal, calculating total energy of the detected sequence signals, comparing the total energy with a threshold, and if the total energy exceeds the threshold as a result of the comparison, the feedback information is And a base station for determining that it is a NACK signal and Is each of the sequence, contains the sequence of the same number as the antennas having orthogonality to each other, and a signal sequence.

The present invention can reduce the feedback frequency resources used in the multicast transmission by using the common feedback channel scheme, and the performance can be greatly improved as the number of user terminals in the cell increases. In addition, due to an increase in signal transmission paths and fading for each path due to a user terminal using a plurality of antennas, a certain performance improvement may be expected. Since the user terminal transmits the NACK signal in the form of orthogonal sequences for each antenna, the base station increases the success rate of receiving feedback information, thereby reducing the number of retransmissions, thereby enabling efficient frequency operation as a whole.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

Hereinafter, the present invention proposes a method and apparatus for transmitting feedback information to a base station through a common feedback channel by user terminals each having a plurality of antennas in multicast transmission based on a common feedback channel scheme. Herein, it is assumed that the number of antennas of each of the user terminals is the same.

According to the present invention, when the feedback information is a NACK signal, the NACK signal is generated in a sequence form corresponding to the number of antennas of the user terminals. At this time, the sequence generated for each antenna number is orthogonal to each other. If the feedback information is an ACK signal, no signal is transmitted to the base station.

1 is a block diagram of a transmission resource block of a common feedback channel according to an embodiment of the present invention.

Referring to FIG. 1, a transmission resource of a common feedback channel includes a total of N blocks in a two-dimensional area including a frequency axis and a time axis, and each block includes a total of M subblocks.

)과 두 번째 안테나를 통해서 송신되는 제2수열(

)은 하기 <수학식1>과 같이 표현된다.As an example, assume that each of the user terminals has two antennas. The feedback information of the user terminals is represented by two sequences corresponding to the two antennas. At this time, the two sequences are orthogonal to each other. That is, the first sequence transmitted through the first antenna (

) And the second sequence transmitted through the second antenna (

) Is expressed by Equation 1 below.

으로 표현되고, 상기 제1수열과 직교하는 제2수열은

으로 표현된다.For example, assuming that the total sample number M is '8', the first sequence is

Represented by, the second sequence orthogonal to the first sequence is

.

2 is a signal flowchart of a common feedback channel operated between at least one user terminal and a base station according to an embodiment of the present invention. Here, a description will be given on the assumption that the at least one user terminal is provided with two antennas, but other cases are also possible.

Referring to FIG. 2, in step 101, the base station transmits the same data packet to user terminals located in a cell through a downlink multicast transmission channel.

In step 102, the user terminals receiving the same data packet decode the received same data packet. In step 103, any of the user terminals checks whether the received same data packet has been previously received and successfully decoded. This is because, if the received same packet is a retransmitted data packet, if it was previously received and the decoding succeeded, it is not necessary to decode again and determine whether the success is successful. For example, assume that the same data packet received is a data packet that was previously received and successfully decoded. In this case, it is assumed that the same data packet is decoded again without undergoing the checking step of step 103. In this case, an ACK signal indicating the successful decoding of the same data packet has already been transmitted to the base station. However, if the decoding performed again fails, a situation occurs in which the NACK signal for the same data packet received is retransmitted to the base station. Therefore, the overall throughput may be lowered due to the above situation, and thus, a check step of 103 is required.

As a result of the checking in step 103, if the same data packet has been previously received and successfully decoded, in step 108, the arbitrary user terminal waits to receive the next data packet. In this case, the arbitrary user terminal does not transmit ACK separately.

If the received same data packet has not been successfully received and decoded before, as a result of the checking in step 103, the arbitrary user terminal performs decoding of the received same data packet in step 104, and then the success thereof is determined. Determine whether or not. If the result of the determination is successful, the flow proceeds to step 108.

If the determination fails, in step 105, the arbitrary user terminal transmits a NACK signal for decoding the received same data packet to the base station through the common feedback channel. In this case, the NACK signal is transmitted in a form of orthogonal to each other through each of the two antennas provided by the user terminal.

In step 106, the base station monitors the common feedback channel, receives a NACK signal, and proceeds to step 107. In step 107, the base station measures an energy value of the received NACK signal through an energy detection method, and proceeds to step 109. In step 109, the base station compares whether the measured energy value of the NACK signal exceeds a threshold. If the result of the comparison does not exceed the threshold value of the energy value of the measured NACK signal, the process proceeds to step 120. In step 120, the base station determines that the NACK signal received in step 106 is an ACK signal. That is, it is determined that none of the user terminals that have received the data packet have transmitted a NACK signal, and proceeds to step 122.

In step 122, the base station prepares to transmit the next data packet.

As a result of the comparison, when the measured energy value of the NACK signal exceeds the threshold, in step 110, the base station determines that there is a user terminal that has transmitted the NACK signal among the user terminals, and the number of times of receiving the NACK signal Count and proceed to step 111. In step 111, the base station compares whether the number of reception of the counted NACK signal exceeds the number of restricted NACK signals. As a result of the comparison, when the number of reception of the counted NACK signal does not exceed the number of limited NACK signals, in step 112, the base station prepares to retransmit the same data packet transmitted in step 101.

If the number of reception of the counted NACK signal exceeds the number of the limited NACK signal as a result of the comparison, in step 121, the base station determines that the same data packet transmitted in step 110 has failed and proceeds to step 122 . This is because the base station receives the NACK signal of the data packet continuously transmitted when the reception state with any user terminal is not good, so as to prevent a situation in which the overall throughput falls.

3 is a structural diagram of a user terminal and a base station using two antennas according to an embodiment of the present invention.

Referring to FIG. 3, the user terminal 200 includes a receiver 201, a controller 202, a decoder 203, a NACK signal generator 204, and sequence generators 205-1 and 205-2. And two antennas 206-1 and 206-2.

The receiver 201 receives a data packet transmitted from the base station 210 through a downlink multicast transmission channel and delivers the data packet to the decoding unit 203. In this case, the data packet is equally received by a plurality of user terminals including the user terminal 200 through the downlink multicast transmission channel.

The decoding unit 203 decodes the received data packet and then transmits whether the decoding is successful to the NACK signal generation unit 204.

The controller 202 checks whether the received data packet has been previously received and decoded successfully. If the test result has not been successfully decoded, the controller 202 controls the NACK signal generator 204 to generate a NACK signal. If the inspection result has been successfully decoded, the controller 202 controls the receiver 201 to wait for reception of the next data packet.

The NACK signal generator 204 outputs a NACK signal to each of the sequence generators 205-1 and 205-2 when the controller 202 controls to generate the NACK signal. Each of the sequence generators 205-1 and 205-2 generates the input NACK signal as an orthogonal sequence, for example, two sequences consisting of two elements, [1 1] and [1 -1]. Transmit to the base station through each antenna 206-1,206-2. The sequence indicates a signal type transmitted only when a NACK signal is generated in the common feedback channel.

The base station 210 determines the reception antenna 211, the correlators 212-1 and 212-2, the squarers 214-1 and 214-2 of the absolute value, the adder 216 and the NACK / ACK determination. Part 218 is included.

The base station 210 receives feedback information on whether the decoding of the data packet is successful from user terminals that transmit the data packet.

The base station 200 receives feedback information transmitted from the user terminal 200 through the receiving antenna 211 and transmits the feedback information to the correlators 212-1 and 212-2. In this case, the NACK signal transmitted from the user terminal 200 is received in a form in which a sequence signal [1 1] and a sequence signal [1 -1] are combined.

The correlators 212-1 and 212-2 detect the sequence signal [1 1] and the sequence signal [1-1] from the received sequence signal, respectively, to obtain the absolute squarers 214-1 and 214-2. Will output

를 상기 NACK/ACK 판단부(218)로 출력한다.The absolute squarers 214-1 and 214-2 square the absolute values of the input sequence signals to detect energy and output the energy to the adder 216. The adder 216 sums the input energy values and synthesizes the energy values.

Is output to the NACK / ACK determination unit 218.

는 하기 <수학식2>와 같이 계산된다.Specifically, the squares of the absolute values 214-1 and 214-2 and the adder 216 are obtained through the operation.

Is calculated as in Equation 2 below.

은 n번째 블록의 m번째 수신 신호를 나타내고,

은 상기 안테나(206-1)를 통해서 송신되는 수열의 엘리먼트를 나타내고,

은 상기 안테나(206-21)를 통해서 송신되는 수열의 엘리먼트를 나타낸다.Occupation,

Denotes the mth received signal of the nth block,

Represents an element of a sequence transmitted through the antenna 206-1,

Denotes a sequence of elements transmitted via the antennas 206-21.

개인 경우, 상기

는 하기 <수학식3>과 같이 계산된다.Antenna count of user terminal

If personal

Is calculated as in Equation 3 below.

를 임계값

와 비교한다. 상기 비교 결과는 하기 <수학식 4>와 같이 판단된다. Then, the NACK / ACK determination unit 218 is the

Threshold

Compare with The comparison result is determined as in Equation 4 below.

가 상기

를 초과할 경우, 상기 기지국은 상기 사용자 단말로부터 수신한 피드백 정보가 NACK 신호라 판단한다. 또한, 상기 비교 결과, 상기

가 상기

이하일 경우, 상기 사용자 단말로부터 수신한 피드백 정보가 ACK 신호라 판단한다.That is, the comparison result, the

Remind

When exceeding, the base station determines that the feedback information received from the user terminal is a NACK signal. In addition, as a result of the comparison,

Remind

In the following case, it is determined that the feedback information received from the user terminal is an ACK signal.

에 따라 사용자 단말이 송신한 피드백 정보 수신에 대한 오류 검출(miss detection)과 거짓 알람(false alarm)의 발생 확률이 달라진다. 상기 오류 검출은 상기 피드백 정보가 NACK 신호였으나 ACK 신호로 잘못 판단하는 경우 사용되며, 상기 거짓 알람은 상기 피드백 정보가 ACK 신호였으나 NACK 신호로 잘못 판단하는 경우 사용된다.The threshold

Accordingly, the probability of occurrence of error detection and false alarm for receiving feedback information transmitted from the user terminal varies. The error detection is used when the feedback information is a NACK signal but is incorrectly determined as an ACK signal. The false alarm is used when the feedback information is an ACK signal but is incorrectly determined as a NACK signal.

은 상기 거짓 알람을 기준으로 결정한다. 이 경우, 채널의 SNR(Signal to Noise Ratio) 환경과 상관없이 임계값이 일정하면, 상기 거짓 알람의 발생 확률 역시 일정하다. 따라서 목표값을 만족하는 거짓 알람의 발생 확률 값에 해당하는 에너지값을 임계값으로 지정하고, 그에 따라 에너지 검출을 수행하면 각 SNR 환경에 따른 차등적인 오류 검출의 발생 확률을 구할 수 있다.Generally, the threshold

Is determined based on the false alarm. In this case, if the threshold is constant regardless of the signal to noise ratio (SNR) environment of the channel, the probability of occurrence of the false alarm is also constant. Therefore, if the energy value corresponding to the occurrence probability value of the false alarm satisfying the target value is designated as the threshold value, and the energy detection is performed accordingly, the probability of occurrence of differential error detection according to each SNR environment can be obtained.

을 결정한다.The threshold value is considered in consideration of a probability of occurrence of each of the error detection and the false alarm.

.

First, when the probability of occurrence of the false alarm is determined as a constant value, the threshold is determined as a value that satisfies the probability of occurrence of the false alarm calculated as in Equation 5 below.

는 상기 거짓 알람의 발생 확률을 나타내고, N은 공용 피드백 채널의 전송 자원의 블록 개수를 나타내고, M은 상기 블록에 포함되는 서브 블록의 수를 나타내고,

는 NACK 신호를 나타내는 수열의 샘플 에너지 즉,

를 나타내고,

은 잡음 신호의 I 축 또는 Q 축의 평균 전력을 나타낸다.here,

Represents a probability of occurrence of the false alarm, N represents the number of blocks of transmission resources of the common feedback channel, M represents the number of sub-blocks included in the block,

Is the sample energy of the sequence representing the NACK signal,

Lt; / RTI &gt;

Represents the average power of the I or Q axis of the noise signal.

Second, when determining the occurrence probability of the error detection based on a target SNR value, it is determined to a value that satisfies the occurrence probability of the error detection calculated as shown in Equation 6 below.

이고,

은 사용자 단말의 동작을 보장해야 하는 최소 SNR 값을 나타낸다.here,

ego,

Represents a minimum SNR value that should guarantee the operation of the user terminal.

을 결정한다.As described above, the present invention provides the threshold value that satisfies Equation (5) or (Equation 6).

.

4A and 4B are structural diagrams of a user terminal and a base station using four antennas according to an exemplary embodiment of the present invention.

Referring to FIG. 4A, the user terminal 300 includes a receiver 301, a controller 302, a decoder 303, a NACK signal generator 304, and sequence generators 305-1 to 305-. 4) and four antennas 306-1 to 306-4. Since the remaining components of the user terminal 300 except for the sequence generators 305-1 to 305-4 operate in the same manner as described with reference to FIG. 3, a detailed description thereof will be omitted.

The NACK signal generator 304 outputs a NACK signal to each of the sequence generators 305-1 to 305-4 when the controller 302 controls the NACK signal to be generated. Each of the sequence generators 305-1 to 305-4 is orthogonal to one another, for example, [11111111], [1111-1-1-1-1], and [11-1-111-1-1] And [1-11-11-11-11-1], that is, a signal is generated in four sequences consisting of eight elements and transmitted to the base station through each of the antennas 306-1 to 306-4. That is, as the number of antennas increases compared to FIG. 2, a sequence corresponding to the number of antennas is transmitted to the base station 310. The sequence indicates the type of signal used in the common feedback channel.

Referring to FIG. 4B, the base station 310 includes a reception antenna 311, correlators 312-1 to 312-4, absolute squarers 314-1 to 314-4, and an adder ( 316 and the NACK / ACK determination unit 318.

The base station 310 receives feedback information on whether the decoding of the data packet is successful from user terminals that transmit the data packet. The base station 310 receives feedback information transmitted from the user terminal 300 through the reception antenna 311 and transmits the feedback information to the correlators 312-1 to 312-4. At this time, the NACK signal transmitted from the user terminal 300 is a sequence signal [11111111] and [1111-1-1-1-1], [11-1-111-1-1] and [1-11- 11-11-1] is received in a combined form.

The correlators 312-1 to 312-4 each include a sequence signal [11111111], a sequence signal [1111-1-1-1-1], and a sequence signal [11-1] from the received sequence signal. -111-1-1] and a sequence signal [1-11-11-11-1] are detected and output to the absolute squarers 314-1 to 314-2.

를 상기 NACK/ACK 판단부(318)로 출력한다. 구체적으로, 상기 절대값의 제곱기들(314-1~314-4)과 상기 가산기(316)의 동작을 통해서 획득되는

는 상기 <수학식3>을 사용하여 계산된다. 이후, 상기 NACK/ACK 판단부(318)는 상기

를 임계값

와 비교한다. 상기 비교 결과, 상기

가 상기

를 초과할 경우, 상기 사용자 단말로부터 수신한 피드백 정보가 NACK 신호라 판단한다. 또한, 상기 비교 결과, 상기

가 상기

이하일 경우, 상기 사용자 단말로부터 수신한 피드백 정보가 ACK 신호라 판단한다.The absolute squarers 314-1 to 314-4 each square the absolute value of the input sequence signal to detect energy and output the energy to the adder 316. The adder 316 sums the input energy values and combines the energy values.

Is output to the NACK / ACK determination unit 318. Specifically, the squares of the absolute values 314-1 to 314-4 and the adder 316 are obtained through the operation.

Is calculated using Equation 3 above. Thereafter, the NACK / ACK determination unit 318

Threshold

Compare with As a result of the comparison,

Remind

If exceeds, it is determined that the feedback information received from the user terminal is a NACK signal. In addition, as a result of the comparison,

Remind

In the following case, it is determined that the feedback information received from the user terminal is an ACK signal.

Meanwhile, in the process of transmitting the feedback information, the magnitude of the sequence signal representing the corresponding feedback information is changed by the channel environment. However, the antennas 306-1 to 306-4 may transmit a sequence signal having orthogonality to each other to separate signals of a corresponding sequence from each of the correlators 312-1 to 312-4 that receive the sequence signals. Will be. Therefore, as a result, orthogonality between the sequences can be maintained, and the sequence can be increased by increasing the number of antennas.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the appended claims, but also by the equivalents of the claims.

1 is a diagram of a transmission resource block structure of a common feedback channel according to an embodiment of the present invention;

2 is a signal flow diagram in a common feedback channel operated between at least one user terminal and a base station according to an embodiment of the present invention.

3 is a structural diagram of a user terminal and a base station using two antennas according to an embodiment of the present invention.

4A and 4B are structural diagrams of a user terminal and a base station using four antennas according to an embodiment of the present invention.

Claims (14)

A method for transmitting feedback information by a user terminal using at least two antennas in a communication system, the method comprising: Receiving a data packet from a base station through a downlink multicast transmission channel; Decoding the data packet and checking whether the data packet has been successfully decoded; When the decoding of the data packet fails as a result of the checking, generating a NACK signal indicating failure of decoding of the data packet using the same number of sequences as the number of antennas; Transmitting the NACK signal to the base station through a common feedback channel; Each of the generated sequences has orthogonality to each other and includes a sequence signal. In the communication system, a base station receives feedback information, Transmitting a data packet to a plurality of user terminals through a downlink multicast transmission channel; Receiving feedback information indicating whether the decoding of the data packet is successful from the at least one user terminal having received the data packet among the user terminals through the common feedback channel; Detecting a sequence signal corresponding to each of at least two antennas included in the at least one user terminal from the feedback information; Calculating a total energy of the detected sequence signals and comparing the total energy with a threshold; Determining that the feedback information is a NACK signal when the total energy exceeds the threshold as a result of the comparison; The feedback information includes the same number of sequences as the antennas, and each of the sequences has orthogonality to each other and includes a sequence signal. The method of claim 2, The threshold is determined taking into account the probability of error detection and false alarms; The error detection is generated when feedback information indicating a NACK signal is incorrectly determined as an ACK signal, and the false alarm occurs when feedback information indicating an ACK signal is incorrectly determined as a NACK signal. . The method of claim 3, The threshold value is the number of blocks of transmission resources of the common feedback channel, the number of sub-blocks included in each block, and the average power of the I-axis or Q-axis of the sample energy and noise signal of the sequence representing the NACK signal. And determining a value that satisfies the occurrence probability of the false alarm. The method of claim 4, wherein The threshold value is determined as a value that satisfies the probability of occurrence of the false alarm using the following equation, wherein the probability of occurrence of the false alarm has a predetermined value. &Lt; Equation &

here,

Represents the probability of occurrence of the false alarm,

Is a threshold value, N represents the number of blocks of transmission resources of the common feedback channel, M represents the number of sub-blocks included in the block,

Is the sample energy of the sequences representing the NACK signal, i.e.

Lt; / RTI &gt;

Is an element of a first sequence of sequences equal to the number of antennas,

Is an element of a second sequence of sequences of the same number as the number of antennas,

Represents the average power of the I or Q axis of the noise signal. The method of claim 3, The threshold value is a feedback information receiving method of a base station, characterized in that the value is determined to satisfy the probability of occurrence of the error detection using a minimum SNR that should ensure the operation of each of the at least one user terminal. The method of claim 6, The threshold value, the feedback information receiving method of the base station, characterized in that determined based on the target SNR value using the following equation, to satisfy the probability of occurrence of the error detection. &Lt; Equation &

here,

Is the probability of occurrence of the error detection, Is the threshold,

ego,

Is the sample energy of the sequences representing the NACK signal, M is

Is Gaussian noise, M is the number of subblocks of each block constituting the transmission resource of the common feedback channel,

Represents a minimum SNR value that should guarantee the operation of each of the at least one user terminal. An apparatus for transmitting feedback information in a communication system including a user terminal using at least two antennas for transmitting feedback information, the apparatus comprising: Receiving a data packet transmitted from a base station through a downlink multicast transmission channel, decoding the data packet, confirming whether the decoding of the data packet is successful, and if the decoding of the data packet fails as a result of the checking, the data A user terminal generating a NACK signal indicating failure of decoding of a packet by using the same number of sequences as the number of antennas, and transmitting the NACK signal to the base station through a common feedback channel; Each of the generated sequences is orthogonal to each other and includes a sequence signal. An apparatus for receiving feedback information in a communication system, Feedback information indicating whether the decoding of the data packet is successful from at least one user terminal that transmits a data packet to a plurality of user terminals through a downlink multicast transmission channel and receives the data packet among the user terminals. Is received through a common feedback channel, detects a sequence signal corresponding to each of at least two antennas provided by the at least one user terminal from the feedback information, calculates the total energy of the detected sequence signals, and then A base station for comparing a total energy with a threshold, and determining that the feedback information is a NACK signal when the total energy exceeds the threshold as a result of the comparison; And the feedback information includes the same number of sequences as the antennas, and each of the sequences has orthogonality to each other and includes a sequence signal. 10. The method of claim 9, The threshold is determined in consideration of the probability of error detection and false alarms. The error detection is generated when feedback information indicating a NACK signal is incorrectly determined as an ACK signal, and the false alarm is generated when feedback information indicating an ACK signal is incorrectly determined as a NACK signal. . The method of claim 10, The threshold may include a number of blocks of transmission resources of the common feedback channel, a number of subblocks included in each block, a sample energy of sequences representing the NACK signal, and an average power of I or Q axes of a noise signal. And the feedback information is determined as a value that satisfies the occurrence probability of the false alarm. The method of claim 11, The threshold value is determined as a value that satisfies the probability of occurrence of the false alarm using the following equation, wherein the probability of occurrence of the false alarm has a predetermined predetermined value. &Lt; Equation &

here,

Represents the probability of occurrence of the false alarm,

Is a threshold value, N represents the number of blocks of transmission resources of the common feedback channel, M represents the number of sub-blocks included in the block,

Is the sample energy of the sequence of samples representing the NACK signal,

Lt; / RTI &gt;

Is an element of a first sequence of sequences equal to the number of antennas,

Is an element of a second sequence of sequences of the same number as the number of antennas,

Is the average power of the I or Q axis of the noise signal. 10. The method of claim 9, And the threshold value is determined as a value that satisfies the probability of occurrence of the error detection using a minimum SNR value that should guarantee the operation of the user terminal. The method of claim 13, And the threshold value is determined as a value that satisfies the probability of occurrence of the error detection, which is determined based on a target SNR value using the following equation. &Lt; Equation &

here,

Is the probability of occurrence of the error detection,

Is the threshold,

ego,

Represents the sample energy of the sequence representing the NACK signal, and M is

Is Gaussian noise, M is the number of subblocks of each block constituting the transmission resource of the common feedback channel,

Represents a minimum SNR value that should guarantee the operation of each of the at least one user terminal.

Images