KR20080021494A - System and method of multi-user multiple transmitting and receiving antenna communications - Google Patents

Abstract

A multi-user multi-transceiving antenna system and a method are provided to enable plural receivers to generate feedback information by extracting channel states of grouped antennas connected with a transmitter and to send the generated information, thereby decreasing feedback capacities. When plural pilot signals are received from a transmitter(100), a receiver(200) generates feedback information by measuring quality of channels through which the plural pilot signals are transmitted, and transmits the generated feedback information to the transmitter(100). When the generated feedback information is received, the transmitter(100) analyzes the received feedback information to schedule streams transmitted to the receiver(200). The transmitter(100) consists of a controller(110), a feedback information processor(140), a coding and modulating unit(120) and a multi-outputting unit(130), and the receivers(200) comprises a quality measuring unit(210), a detecting unit(220), a multi-receiving unit(230) and a decoding modulator(240).

Description

MULTI-USER MULTI-USER MULTIPLE TRANSMITTING AND RECEIVING ANTENNA COMMUNICATIONS}

The present invention relates to a MIMO system, and more particularly, to a multi-user MIMO system and method for scheduling streams transmitted from a transmitter to one or more receivers, that is, multiple users.

In general, in third generation wireless mobile communications such as wideband code division multiple access (WCDMA), high-rate data transmission supports wireless multimedia services. High Speed Downlink Packet Access (HSDPA) is a packet-transfer 3G system that improves WCDMA and supports 10Mbps transmission speed. It also includes various enhancement techniques such as Adaptive Modulation and Coding (AMC), Hybrid Automatic Repeat Request (HARQ), fast cell selection (FCS), and multi-input multiple-output (MIMO) antenna processing.

The MIMO technology increases the spectral efficiency by increasing the data rate through the transmitter / receiver multiple antenna processing without increasing the frequency of use. In the MIMO system considering the actual mobile communication environment, an algorithm for scheduling a user is important. While Single-User MIMO focuses on increasing point-to-point link capacity, Spatial Division Multiple Access (SDMA) scheduling in Multiple-User MIMO (MIMO). Emphasis is placed on improving system transmission capacity. Single-user MIMO can also be used for user scheduling, but its performance is not as good as that of the multi-user method due to the limitation that only one user supports in the space axis.

In the multi-user MIMO, an efficient user scheduling scheme considering various transmission mode support and uplink feedback signaling usage optimization is required to obtain optimal performance.

Accordingly, in view of the foregoing, the present invention transmits different pilot signals to receivers for each antenna included in the transmitter, and the receiver generates feedback information for each stream group determined through the pilot signals received for each antenna. Upon transmission to the transmitter, the transmitter analyzes the received feedback information and proposes a MIMO system and method for scheduling a stream transmitted to receivers to various users in various modes.

In addition, the present invention provides an active transport stream group which is additional information necessary for flexible single-user mode and multi-user channel quality value of a stream group index selected by a receiver, information required for multi-user mode base station scheduling, and a corresponding stream group. It provides a receiver for generating feedback information including a rank and a single user channel quality value according to this group number designation. When generating a multi-user channel quality value and generating a single user channel quality value, the same receiver or different receivers may be assumed depending on the receiver situation. For example, a linear receiver may be assumed when generating multi-user channel quality values, and an advanced receiver such as SIC or modified ML may be assumed when generating a single user channel quality value.

In addition, when the feedback information is received from a plurality of receivers, the present invention provides a transmitter that analyzes the received feedback information and schedules a stream transmitted to the receiver in various modes to multiple users.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention.

In a preferred embodiment according to the present invention, when a plurality of pilot signals are received from a transmitter, the receiver determines the quality of the channels through which the plurality of pilot signals are transmitted, generates feedback information, and transmits the generated feedback information to the transmitter. And, when the generated feedback information is received, and analyzes it to provide a MIMO system consisting of a transmitter for scheduling the stream transmitted to the receiver in a variety of modes.

In a preferred embodiment of the present invention, a process of transmitting a pilot signal to a receiver for each antenna included in the transmitter, a process for generating feedback information through the pilot signal received for each stream group, and the transmitter When a plurality of feedback information is received from a plurality of receivers, the received feedback information is analyzed and transmitted to a user having the highest channel quality among the analyzed feedback information by scheduling a stream in a multi-user mode or a flexible single-user mode. Provided is a stream scheduling method in a MIMO system.

In addition, according to an embodiment of the present invention, a feedback is generated by using a multiple output unit for transmitting a pilot signal for each of a plurality of antennas to a plurality of receivers, and a pilot signal received by the transmitter for each group antenna from the plurality of receivers. When the information is received, a transmitter for scheduling a stream in a MIMO system comprising a feedback information processor for determining a scheduling method of the stream, and a control unit for controlling the transmission of the stream to the receiver using the determined scheduling method.

In addition, in a preferred embodiment according to the present invention, the index of the stream group and the maximum quality value of the stream group having the maximum channel quality required for multi-user mode scheduling using a pilot signal received from a plurality of group antennas included in the transmitter. Multiplying the channel quality of the remaining group antennas except for the group antennas having the maximum quality value and the single user support additional support for the single user mode without overlapping the feedback content for the multi-user mode. And generating feedback information by varying the number (rank) information of the streams transmitted according to the quality values of the residual group antennas measured by the multiple methods, and transmitting the generated feedback information to the transmitter. Feedback of receivers in a MIMO system Provide a production method.

In addition, in the preferred embodiment according to the present invention, the index of the stream group having the maximum channel quality for the multi-user mode and the maximum quality value of the stream group are obtained by using a pilot signal received from a plurality of group antennas provided in the transmitter. A quality measurer to extract, a detector to detect channel quality for an additional single user mode required for a single user mode not included in the feedback in multiple ways, a multiple receiver to multi-receive multiple streams transmitted from the detector, The present invention provides an apparatus for generating feedback information of a receiver in a MIMO system including a decoding and demodulation unit for decoding and demodulating the multiple received streams.

As described above, according to the present invention, a plurality of receivers extract the channel state of the group antenna connected to the transmitter to generate feedback information, and then transmit the information to the transmitter, thereby reducing the feedback capacity than when feeding back the channel state of each antenna. It works.

In addition, the transmitter is configured to receive the channel status from a plurality of receivers, so that the stream to be transmitted to the receiver can be selectively scheduled and transmitted to different users for each antenna group, thereby increasing transmission capacity.

In addition, the feedback information according to the present invention is equal to the size of the feedback information applied to each conventional single user or multiple users. Therefore, there is an effect that can support both single-user and multi-user mode without increasing the size of the feedback information. In addition, since the feedback information includes a rank value indicating a beamforming mode or a reception interference cancellation mode, the feedback information may be adaptively used in a channel situation when operating in a single user mode.

Hereinafter, a multi-user multi-antenna system and method according to the present invention will be described with reference to the drawings.

1 is a view showing the structure of a multi-user MIMO transmission and reception system according to an embodiment of the present invention.

As shown, a multi-user multi-antenna system according to an embodiment of the present invention consists of a transmitter (eg, a base station) and a plurality of receivers (eg, a terminal). The transmitter 100 includes a plurality of antennas, and the provided antennas may be grouped into a predetermined number (for example, two) as shown. Streams transmitted and received between the transmitter and the receiver may be performed through grouped antennas. Multiple-user Multiple antenna system refers to transmitting data or streams to multiple receivers through multiple antennas at a specific time. That is, the stream may be transmitted to multiple receivers (sometimes referred to as 'multi-user transmission') through the antenna of the transmitter 100 at a particular time, or only one receiver may be transmitted at a particular time (this is called Sometimes referred to as 'single user transfer'). As such, in order to transmit a stream to multiple receivers or a single receiver using multiple antennas provided in the transmitter, such as channel quality, throughput, capacity, performance, etc. You need to know the information. Then, the transmitter transmits the stream through the identified information (i.e., a method of transmitting to a single or multiple receivers using the multi-group antenna of the transmitter (multi-user method) or one of the transmitters using one group antenna). Determine how to send to the receiver (single user method). The group antenna includes a column group or an antenna beam group using a precoding matrix. As described above, in order for the transmitter 100 to select a transmission method, the plurality of receivers 200 and 300 first analyze and extract information about the transmitter and the channel formed therein and transmit the information to the transmitter. Transmitter 100 determines the multi-user mode or single-user mode through this information received from multiple receivers 200, 300. As a result, when the transmission method is selected, the overall network throughput or performance may be improved by the transmitter scheduling and transmitting the stream to the receiver.

2 is a block diagram of a transmitter and a receiver in a multi-user MIMO transmission and reception system according to an embodiment of the present invention.

As shown, the MIMO transceiving system according to the embodiment of the present invention is composed of a transmitter (for example, a base station) and a plurality of receivers (for example, terminals), but FIG. 2 is provided to clarify the gist of the present invention. Only one receiver is shown.

The transmitter 100 precodes streams (eg, user stream # 1, user stream # 2, ....) received from a plurality of transmitting users, and streams according to the processing result of the feedback information processor 140. And a group antenna having the best channel information, throughput, capacity, or performance from the plurality of receivers, for determining whether to transmit the data in a single user mode or a multi-user mode. A feedback information processor 140 for processing feedback information including an index, a quality value corresponding to the highest capacity, a rank, and a quality value for supporting a mode corresponding to the selected link; When the transmission method is determined through the control unit 110, a coding and modulation unit 120 for coding and performing modulation for each stream and coding and modulation are performed through the coding and modulation unit 120. It is composed of multiple output unit 130 for outputting a stream multiplexed (multiplexed) through a plurality of antennas.

In addition, the receiver 200 uses channel quality information (CQI) of a plurality of antennas connected to the transmitter 100 through a wireless channel using zero forcing (ZF) or minimum mean square error (MMSE) and And / or extracts a Signal to Interference Noise Ratio (SINR) and measures the maximum quality value (e.g., ESN value) and the index of the antenna corresponding to the wireless channel of the maximum ESN through the extracted CQI and / or SINR. An additional quality value that is connected to a quality measuring unit 210 and a plurality of antennas and supports a rank r and a mode corresponding to the rank using Successive Interference Cancellation (SIC) or Beamforming (BF). (E.g., Remain-ESN), determine whether to receive the stream from multiple transmitters at the transmitter or through only one antenna over the maximum ESN, and stream through multiple antennas at the receiver. If the performance is better, the additional quality value to support the mode corresponding to the selected rank, the detector 220 for detecting the rank (r), and the multiple receiver 230 for receiving multiple streams from the multiple antennas And a decoding demodulator 240 for decoding and demodulating the received stream.

Hereinafter, referring to FIG. 2, operations of a transmitter and a receiver in a multi-user MIMO transceiving system according to an embodiment of the present invention will be described.

The operation of the transmitter 100 is as follows.

The control unit 110 included in the transmitter 100 transmits a pilot signal through a plurality of antennas to determine whether a multi-user service or a single user service is performed on streams transmitted from a plurality of transmitting users. Send them. The pilot signal may be a different signal for each antenna provided in the transmitter. Each of the receivers receiving the different pilot signals measures and detects the channel quality for each group antenna determined through a technique such as ZF, MMSE, BF, and SIC, and measures the measured and detected feedback information of the transmitter 100. Feedback to the feedback information processor 140. The feedback information includes an index of the group antenna having the highest capacity, a quality value corresponding to the highest capacity, a rank value indicating a transmission antenna selection (rank = 1) or a reception interference cancellation mode (rank = 2), and a selected rank. Contains additional quality values to support the mode in question.

The index of the maximum group antenna represents the index of the group antenna having the best channel state, performance, and throughput of the channel where the receiver and the transmitter are wirelessly connected. The quality corresponding to the highest capacity represents the channel quality or performance of the best antenna. The rank indicates the value of which method is better performing when the stream is received via only one group antenna (single user method) and when receiving via multiple group antennas (multi user method).

The additional quality value (eg, Remain-ESN) is divided into two types. First, the group antenna having the maximum ESN is excluded by the SIC scheme, and the second group is the ESN of the other group antennas. Second, the maximum ESN is turned off by the BF (Beamforming) technique, and the measured ESN of the remaining group antennas is obtained. In other words, in the first method, the rank is '2', and in the second method, the rank is '1'.

The feedback information processor 140 selects an antenna having the highest channel quality among the analyzed feedback information by analyzing feedback information received from a plurality of receivers. Then, it is determined whether to transmit the stream to the receiver through the single user mode or the multi-user mode to transmit to the control unit 110. The controller 110 may select a precoding function, modulation, and coding. The controller 110 controls the transmitter to transmit a stream input from a plurality of transmitting users according to the information received from the feedback information processor 140 to a plurality of receivers in a single user transmission method or a multi-user transmission method. Perform the procedure to

As such, when the transmission mode is determined under the control of the controller 110, the coding and modulation unit 120 performs encoding and modulation processes on the streams input from the transmitting users, respectively.

The multiple output unit 130 including a plurality of multiplexers and a plurality of transmit antennas for each multiplexer transmits the stream on which the encoding and modulation processes are performed to the receiver through the multiple antennas at the same power. In this case, the transmitter may be configured by grouping a plurality of antennas. In addition, the receiver may also be equipped with multiple antennas.

The operation of the receiver 200 is as follows.

The receiver 200 receives the quality of each channel through different pilot signals received through the respective wireless channels from the transmitter 100, zero forcing (ZF), minimum mean squared error (MMSE), and BF ( Measurement is performed using beamforming and / or successful interference cancellation (SIC) techniques. The index of the group antenna having the highest capacity among the determined antenna groups of the transmitter, the quality value corresponding to the highest capacity, a rank value indicating a transmission antenna selection or a reception interference cancellation mode, and a mode corresponding to the selected rank are supported. Send feedback information including the additional quality value for the transmitter.

In more detail, the quality measuring unit 210 provided in the receiver 200 measures different pilot signals received by a plurality of antennas by using a zero forcing (ZF) or an MMSE technique. Then, it is analyzed whether the quality of the signal transmitted from which antenna of the transmitter 100 is good or which antenna state is connected to which antenna is good. The measurement includes an index of the group antenna having the highest capacity and a quality value corresponding to the capacity of the group antenna. The measured information is transmitted to the detector 220 as described above.

The detector 220 detects the rank and the additional quality value (Remain-ESN) based on the BF technique, the SIC technique, and the information received from the quality measurer 210. The rank is divided into ranks indicating transmission antenna selection (rank = 1) or reception interference cancellation mode (rank = 2). When the four pieces of information are detected, the receiver 200 performs a mode change for receiving a stream in a single user mode or a multi-user mode. When the detected four pieces of information (i.e., the index of the group antenna having the highest capacity, the quality value corresponding to the group antenna, the rank, and an additional quality value for supporting the mode corresponding to the rank) are detected, the receiver The detected feedback information is used to switch to the single user mode for receiving the stream in the BF method or the multi-user mode for receiving in the SIC method. The quality measuring unit 210 feeds back the detected four pieces of information to the feedback information processing unit 140 of the transmitter 100.

After the four pieces of information are transmitted, when the stream is received from the transmitter 100, the multiple receiver 230 provided in the receiver 200 demultiplexes the streams received from the plurality of antennas. The demodulation and decoding processes are performed respectively. After this process, the received stream is stored in the receiver or finally displayed to the user through the application layer (Application Layer).

Hereinafter, an equation for extracting feedback information from a receiver in a multi-user MIMO transmission / reception system according to an embodiment of the present invention will be described with reference to FIG. 2.

First, as shown in Figure 1, the MIMO system according to the present invention is composed of a transmitter and two receivers consisting of two group antennas. As such, the signals transmitted and received through the antennas provided in the transmitter and the receiver may be represented by Equation 1 below.

Y (t) = H * X (t) + n (t)

In Equation 1, Y (t) denotes a signal received by the receiver at 't' time, and 'H' denotes a matrix representing the downward characteristic of the channel. In addition, X (t) represents the signal input to the transmitter, n (t) represents the noise generated due to the characteristics of the radio channel during stream transmission.

For example, assuming that the number of antennas is two from the transmitter and two receivers, the signals 'Y = {y1, y2}' respectively received at the 't' time are expressed as Equation 2 below.

In Equation 2, 'h' represents a channel to which a transmitter and a receiver are wirelessly connected. That is, 'h12' represents channel quality information (CQI) or effective signal-to-interference noise ratio (ESN) of a channel for transmitting user data input to the transmitter to the receiver '1' through the antenna '2'. Each 'h' is grouped into a plurality of antennas.

In this way, in order to group the antennas of the transmitter, the following Equations 3 and 4 are used.

은 전송 안테나 'm'의 CQI이고,

과

는 실제 처리량 성능과 Shannon 커패시티사이의 성능 차이이다. In Equation 3, and Equation 4

Is the CQI of the transmit antenna 'm',

and

Is the difference in performance between actual throughput performance and Shannon capacity.

), 상기 최고의 용량에 해당되는 품질 값(

), 랭크(r), 선택한 랭크에 해당되는 모드를 지원하기 위한 추가 품질 값(

)과 같은 피드백 정보를 추출 및 분석한다. As such, when a stream or pilot signal is received through a plurality of antennas, each receiver receives an index of the group antenna having the highest capacity.

), The quality value corresponding to the highest dose (

), Rank (r), and additional quality values to support the mode corresponding to the selected rank (

Extract and analyze feedback information.

는

로서 그룹 안테나가 2개일 경우 최대 CQI 값을 나타내고,

는 상기 최대 CQI 값을 갖는 그룹의 인덱스 정보를 나타낸다. 또한

는 선택한 랭크에 해당되는 모드를 지원하기 위해서 추가로 요구되는 품질 값을 나타내고, 'r'은 BF 방법과 SIC 방법을 통해서 파악된 채널 품질에 따라 스트림을 단일 사용자 모드 또는 다중 사용자 모드로의 수신을 나타내는 계수이다. remind

Is

As two group antennas, it represents the maximum CQI value.

Represents index information of the group having the maximum CQI value. Also

Indicates additionally required quality values to support the mode corresponding to the selected rank, and 'r' indicates that the stream can be received in single-user mode or multi-user mode depending on the channel quality determined by the BF and SIC methods. Coefficients to indicate.

The following process represents an equation for obtaining the feedback information as described above.

First, each receiver measures a CQI for each antenna of a transmitter connected to itself and a wireless channel. The CQI can be obtained through Equation 5 below.

Each receiver may measure channel quality of each antenna by using Equation 5 above.

는 각 수신기에서 처음 디코딩되어야 하며,

는 랭크 즉, 'r'에 관계된다. Also,

Must be decoded first on each receiver,

Is related to the rank, ie, 'r'.

는 다음 <수학식 6>으로 표현될 수 있다. therefore,

Can be expressed as Equation 6 below.

이다. In Equation 6 above

to be.

는 빔포밍 전송(beamforming transmission, BF)의 수신된 SINR로서, 'm=1,2'인 경우 다음 <수학식 7>과 같이 표현된다. Through Equation 6 above

Is the received SINR of the beamforming transmission (BF), and when 'm = 1,2' is expressed by Equation 7 below.

는 빔포밍 전송에 적용되는 전송 안테나 'm'의 CQI를 나타내며, 다음 <수학식 8>로 표현된다 In Equation 7 above

Denotes the CQI of the transmit antenna 'm' applied to beamforming transmission, and is represented by Equation 8 below.

이다. 또한,

는 그룹 SIC 수신의 수신된 SINR로서 'm=1,2'인 경우 다음 <수학식 9>로서 표현된다. In Equation 8 above

to be. Also,

Is the received SINR of the group SIC reception, where m = 1,2, is represented by:

는 SIC 처리로 다른 그룹에 속한 전송 신호들을 삭제한 후, 전송 안테나 'm'의 CQI 값을 나타내며, 다음 <수학식 10>로서 표현된다. In Equation 9 above

Denotes the CQI value of the transmission antenna 'm' after deleting transmission signals belonging to another group by SIC processing, and is represented by Equation 10 below.

'을 결정할 수 있다. By comparing the difference between the throughput of the BF method and the SIC method using the above-described equations,

Can be determined.

By inferring Equation 6, the throughput in the case of the BF scheme and the maximum throughput in the case of the SIC scheme can be obtained.

)과 SIC 전송의 최대 처리량(R_GSIC)은 아래 <수학식 11>로 표현할 수 있다. The maximum throughput of the BF transmission (

) And the maximum throughput of the SIC transmission (R _GSIC ) can be expressed by Equation 11 below.

이

보가 크면,

은 1이고, 그렇지 않으면,

은 2이다.That is, in Equation 11

this

If the beam is big,

Is 1, otherwise,

Is 2.

The information analyzed by the receiver includes an index of the group antenna having the highest capacity among the instantaneous channel capacities of the antenna groups measured by the receiver, a quality value corresponding to the highest capacity, a rank, and a mode corresponding to the selected rank. Analyze additional quality values. The index of the group antenna having the highest capacity and the quality value corresponding to the highest capacity are analyzed through the MMSE, and the additional quality value for supporting the rank and the mode corresponding to the selected rank is analyzed through the SIC.

Multiple receivers in the transmitter's service area perform this analysis for each stream. In addition, the plurality of transmitters transmits the analyzed four pieces of information (that is, an additional quality value for supporting a mode corresponding to the index of the group antenna having the highest capacity, the quality of the group antenna, the rank, and the rank) to the transmitter. .

The transmitter transmits a stream by maximizing bandwidth to a specific receiver having a good channel condition at a specific time based on such information received from a plurality of receivers, or when there are a plurality of receivers that are higher than a predetermined threshold, Send streams to multiple receivers simultaneously.

3 is a flowchart illustrating a method of transmitting / receiving a stream of a transceiver in a multi-user MIMO system according to an exemplary embodiment of the present invention.

Hereinafter, a method of transmitting and receiving a stream in a transceiver in a multi-user MIMO system according to an embodiment of the present invention will be described in detail with reference to FIG. 3.

First, it is assumed that a transmitter for transmitting a stream to a receiver is provided with a plurality of antennas, and the provided antennas are grouped in predetermined number units (eg, group antenna 1 and group antenna 2) as shown in FIG. 1. do. In addition, although the receiver may be provided with a plurality of antennas, the present invention assumes that there is only one antenna of the receiver in order to clarify the gist of the present invention.

When the transmitter receives a plurality of streams to be transmitted from the user to the receiver, the transmitter (for example, the base station) transmits a pilot signal for each antenna to the plurality of receivers (for example, the terminal) in its service area (S100). , S102). The pilot signal may be a different signal. The pilot signal is transmitted to each receiver for each antenna provided in the transmitter. Each of the receivers receiving the pilot signal receives the pilot signal by the number of antennas of the transmitter. The number of received pilot signals also means the number of channels to which the receiver is wirelessly connected to the transmitter.

The receiver measures the quality (eg, bit rate, SINR, throughput, performance, etc.) of the channel through which the pilot signal is transmitted using the received multiple pilot signals, and the index of the group antenna having the highest capacity among the instantaneous channel capacities and the A quality value (ie, an ESN value) corresponding to the capacity of the group antenna is extracted (S104). Then, a rank value indicating a transmission antenna selection (rank = 1) or a reception interference cancellation mode (rank = 2) and an additional quality value for supporting a mode corresponding to the rank are extracted (S106).

When the feedback information is extracted or calculated through the processes S104 and S106, the receiver switches the reception mode to receive the stream in the single user mode or the multi-user mode (S108). That is, the multi-user mode is to receive a stream from a plurality of antennas provided in the receiver, in which case the rank is '2'. On the other hand, the single-user mode is to receive a stream through the antenna of the highest quality (e.g., ESN) among the group antennas provided in the receiver, in which case the rank is '1'. When the reception mode is switched to the reception mode corresponding to the extracted rank value in step S108, the receiver transmits feedback information including the detected four pieces of information to the transmitter (S110).

When receiving the feedback information, when the feedback information is received from all receivers to which the pilot signal is transmitted in step S102, the transmitter analyzes the received feedback information to determine the quality (eg, bit rate, SINR, throughput, performance or the like) to identify the best channel or, among all terminals, the best channel quality of the current terminal is identified (S114). If the channel having the best quality is identified for each receiver in the process (S114) or the terminal having the best channel quality in all the terminal states, the receiver transmits a stream to each receiver to the identified good channel or the channel. The stream is transmitted to the terminal having the best quality (S116).

As described in step S114, since the transmitter analyzes the feedback information transmitted by the plurality of receivers and transmits the stream, even if the receiver wants to receive the service in the multi-user mode, the stream is transmitted in this multi-user mode. You may not receive it.

4 is a flowchart illustrating a stream scheduling method of a transmitter in a multi-user MIMO system according to an embodiment of the present invention.

Hereinafter, a stream scheduling method of a transmitter in a multi-user MIMO system according to an embodiment of the present invention will be described in detail with reference to FIG. 4.

When multiple streams are input to the transmitter, the receiver transmits a pilot signal to the multiple receivers corresponding to the input multiple streams (S200 and S202). The pilot signal may be different for each antenna provided in the transmitter. The pilot signal is transmitted to a plurality of receivers for each antenna of the transmitter. As such, through the pilot signal transmitted to the plurality of receivers, the plurality of receivers analyzes and extracts the quality of the channel set up with them wirelessly, the group index of the antenna having the maximum quality, the maximum quality value of the antenna, the rank value, and the feedback through the same. Generate information. The receiver feeds back the generated feedback information to the transmitter. The rank is a coefficient that indicates which method is better in terms of throughput, capacity or performance when receiving a stream in multi-user mode or single-user mode. That is, if the rank coefficient is '2', it indicates a multi-user mode method, and if the rank coefficient is '1', it indicates a single user mode. Alternatively, when the rank coefficient is '2', the quality of the remaining group antennas (ie, additional quality values for supporting the mode corresponding to the rank) is measured by the SIC technique, and when the rank coefficient is '1', the BF technique is used. It can be seen that the quality of the residual group antenna is measured through.

When the generated feedback information is received from the plurality of receivers, the transmitter analyzes the received feedback information to determine which group antenna indexes have a good channel quality (S204-S206). The process (S206) not only identifies a receiver having a good channel quality but also receives a coefficient having a rank of '2' from a given receiver, considering the channel quality, throughput, performance, etc. of another receiver, The stream may be transmitted in a user manner or vice versa. As such, the reason why the transmitter schedules the stream differently from the receiver's request is because the performance of the overall system or the channel quality of all receivers is taken into account.

For example, if the sum of data rates in a single user mode from a given receiver is greater than the sum of data rates in a multi-user mode, the transmitter sends the stream in single user mode to the given receiver. Alternatively, if the sum of the data rates in the multi-user mode is equal to or greater than the sum of the data rates in the single-user mode, the transmitter transmits the stream to the predetermined receiver in the multi-user mode.

When the transmitter determines the optimal condition for transmitting the stream through the process (S206), the transmitter transmits the stream to the receiver using one or more group antennas (S208).

5 is a flowchart illustrating a method of generating feedback information of a receiver in a multi-user MIMO system according to an embodiment of the present invention.

Hereinafter, a method of generating feedback information of a receiver in a multi-user MIMO system according to an embodiment of the present invention will be described in detail with reference to FIG. 5.

First, in the embodiment of the present invention, it is assumed that two transmitter antennas (Group 1, Group 2).

The feedback information supports the index of the group antenna having the highest quality, the maximum quality value of the group antenna having the maximum quality, the rank and the mode corresponding to the rank among the channels set up wirelessly for each group antenna of the transmitter. Additional quality values to be included.

When the pilot signal is received for each antenna of the transmitter, the receiver measures the quality (ESN 1, ESN 2) or capacity of the channel (ie, the channel set up for each group antenna) on which the pilot signal is received through ZF or MMSE technique. (S302). When the quality or capacity is measured for each group antenna, the index and the maximum quality value (for example, ESN 1) of the group antenna (for example, Group 1) having the maximum capacity or quality are extracted (S304). When the index and quality (eg, ESN 1) are extracted, an additional quality value for measuring a mode corresponding to the selected rank is measured using the SIC technique. Then, after turning off the group antenna corresponding to the ESN1 by using the BF technique, the additional quality value is measured (S306). When ESN 2 is measured by the two methods in the process (S306), the measured data rates (Rsic, Roff) of the two ESN 2 are compared (S308). In step S308, Rsic represents a value of a large data transmission rate among the maximum ESN value of Group 1 and additional quality values excluding Group 1. Roff represents the data rate when the group 1 is trun-offed.

As a result of the comparison in the step (S308), if the Roff is greater than Rsic, a rank value (ie, the rank is '1'), the additional quality value measured after the group antenna 1 is trun-off, the step (S304) In step S312, feedback information including the index of the group antenna having the maximum ESN extracted from and the ESN value of the group antenna having the largest ESN are generated.

If, as a result of the comparison in the step (S308), if the Roff is less than Rsic, the rank value (ie, the rank is '2'), the additional quality value measured using the SIC technique, the quality extracted in the step (S304) For example, the feedback information including the index of the group antenna having the largest ESN and the ESN value of the group antenna having the largest ESN is generated (S314).

When the feedback information is generated in the processes S312 and S314, the receiver switches the stream reception mode to the single user mode or the multi-user mode according to the generated rank value. When the reception mode is switched, the generated feedback information is transmitted to the transmitter.

In the above-described embodiment of the present invention, the content of the maximum number of data uploaded in one cell (ie, relaying cell) (ie, MSx) is balanced. However, the maximum number of terminals, that is, only one terminal, is described. It can also be applied to multiple terminals where the amount of data uploaded at the same time is above a certain threshold.

In addition, although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary and will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a view showing the structure of a multi-user MIMO transceiving system according to an embodiment of the present invention.

2 is a block diagram of a transmitter and a receiver in a multi-user MIMO transmission and reception system according to an embodiment of the present invention.

3 is a flowchart illustrating a method of transmitting / receiving a stream in a transceiver in a multi-user MIMO system according to an embodiment of the present invention.

4 is a flowchart illustrating a stream scheduling method of a transmitter in a multi-user MIMO system according to an embodiment of the present invention.

5 is a flowchart illustrating a method for generating feedback information of a receiver in a multi-user MIMO system according to an embodiment of the present invention.

Claims (38)

Receiving a plurality of pilot signals from a transmitter, measuring the quality of channels through which the plurality of pilot signals are transmitted, generating feedback information, and transmitting the generated feedback information to the transmitter; And When the generated feedback information is received, the multi-user multiple transmit and receive antenna system including a transmitter for analyzing the scheduling and the stream to be transmitted to the receiver. The method of claim 1, wherein the pilot signal The antenna for the transmitter is different from each other, each multi-user multiple transmit and receive antenna system transmitted to the receiver. The method of claim 1, wherein the generated feedback information is At least one of an index of a group antenna having the highest capacity among instantaneous channel capacities of the antenna groups measured by the receiver, a quality of the group antenna, a rank value, and an additional quality value for supporting a mode corresponding to the rank. Multi-user multiple transmit / receive antenna system. The method of claim 1, wherein the transmitter And analyzing feedback information received from a plurality of receivers and transmitting a stream in a single user mode or a multi-user mode through a group antenna having the highest channel quality among the analyzed feedback information. Transmitting a pilot signal to a receiver for each antenna provided in the transmitter; Generating, by the receiver, feedback information through pilot signals received for each determined antenna group; And When the transmitter receives a plurality of feedback information from a plurality of receivers, the transmitter comprises analyzing the received feedback information and scheduling and transmitting the stream in a single user mode or a multi-user mode through a transmission antenna; Stream scheduling method in antenna system. The method of claim 5, wherein the generated feedback information Multiple including at least one of the index of the group antenna having the highest capacity among the instantaneous channel capacity of the antenna groups measured by the receiver, the quality of the group antenna, the rank value and the additional quality value for supporting the mode corresponding to the rank Stream scheduling method in user multiple transmit / receive antenna system. The process of claim 5, wherein the generating of the feedback information is performed. When a pilot signal is received from a plurality of antennas, the capacity is measured for each of the plurality of antennas using the received pilot signal to extract the maximum capacity value, the index of the group antenna having the maximum capacity is extracted, and the transmission is performed. And extracting a rank value indicating an antenna selection or a received interference cancellation mode and extracting an additional quality value for supporting a mode corresponding to the extracted rank. 8. The process of claim 7, wherein extracting the additional quality value Streaming in a multi-user multi-transmit / receive antenna system comprising extracting the quality of the residual group antenna using SIC, turning off the stream having the minimum quality using BF, and extracting the additional quality Scheduling Method. The method of claim 5, wherein the scheduling and transmission of the stream comprises: When a plurality of pieces of feedback information are received from the plurality of receivers, the group antenna index is identified as the receiver having the best channel quality among the plurality of pieces of feedback information, and the stream is determined according to a rank value included in the feedback information. Stream scheduling method in a multi-user multiple transmit / receive antenna system comprising transmitting. The method of claim 5, wherein the transmission process Stream scheduling method in a multi-user multiple transmit and receive antenna system comprising the step of selecting the antenna having the highest quality among the received feedback information. The method of claim 6, wherein the rank is A method for stream scheduling in a multi-user multi-transmit / receive antenna system characterized by indicating transmit antenna selection (rank = 1) or receive interference cancellation mode (rank = 2). Multiple output unit for transmitting a pilot signal to a plurality of receivers for each antenna; A feedback information processor configured to determine a scheduling method of the stream when the receiver receives feedback information generated using the received pilot signal from the plurality of receivers; And Transmitter for scheduling a stream in a multi-user multi-transmit and receive antenna system comprising a control unit for controlling the transmission of the stream to the receiver using the determined scheduling method. The method of claim 12, wherein the received feedback information is The index of the group antenna having the highest channel quality or capacity, the quality of the group antenna having the highest channel quality or capacity, the transmission antenna selection (rank = 1) or the reception interference cancellation mode (rank = 2) A transmitter for scheduling a stream in a multi-user multiple transmit / receive antenna system comprising at least one of a rank value pointing to 2) and an additional quality value for supporting a mode corresponding to the rank. The method of claim 12, wherein the scheduling method A transmitter for scheduling a stream in a multi-user multi-transmit / receive antenna system for scheduling a stream using a single user mode or a multi-user mode according to a value of rank included in the feedback information. The method of claim 14, wherein the scheduling method When the value of the rank is '1', the stream is transmitted to the receiver using the single user mode. When the value of the rank is '2', the multi-user transmits the stream to the receiver using the multi-user mode. A transmitter for scheduling streams in a multiple transmit / receive antenna system. Extracting an index of a group antenna having a maximum channel quality or capacity and a maximum quality value of the group antenna using different pilot signals received from a plurality of antennas provided in a transmitter; Measuring channel quality excluding the group antenna having the maximum quality value by a plurality of methods; Generating feedback information by varying rank information according to the quality values of the group antennas measured by the multiple methods; And Method of generating feedback information of a receiver in a multi-user multiple transmit and receive antenna system comprising the step of transmitting the generated feedback information to the transmitter. The method of claim 16, wherein the multiple methods are After the group antenna having the minimum quality value is turned off using the beamforming (BF) technique, the channel quality of the group antenna is measured, and the channel quality of the group antenna is measured using the successive interference cancellation (SIC) technique. A method for generating feedback information of a receiver in a multi-user multi-reception antenna system comprising a method. 17. The method of claim 16, wherein the channel quality is A method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system including at least one of an efficiency signal to interference noise ratio (ESN), throughput, performance, and channel quality information (CQI). The method of claim 16, wherein the rank information The method for generating feedback information of a receiver in a multi-user multi transmit / receive antenna system, wherein the stream transmitted from the transmitter is information representing one of a single user transmission mode and a multi user transmission mode. The method of claim 16, wherein the generated feedback information is For supporting the index of the group antenna having the highest channel quality or capacity, the quality of the group antenna having the highest channel quality or capacity, the rank value and the mode corresponding to the rank through the pilot signal received for each antenna A method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system including any one or more of additional quality values. The method of claim 20, wherein the rank is A method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system characterized by indicating transmit antenna selection (rank = 1) or receive interference cancellation mode (rank = 2). The multi-user multi transmit / receive antenna system of claim 16, wherein the index of the group antenna with the maximum channel quality and the maximum quality value of the group antenna are measured by Zero Forcing (ZF) or Minimum Mean-Squared Error (MMSE) technique. How to generate feedback information of the receiver. The method of claim 16, wherein the generating process When the feedback information is generated, switching to a stream reception mode according to the rank information, the method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system. 17. The method of claim 16, wherein the channel quality of the group antenna (e.g. m) is

In the multi-user multi-transmit and receive antenna system, h is a matrix representing a channel that the group antennas of the transmitter and the receiver is wirelessly connected, I is the index of the antenna group, SNR is the signal-to-noise ratio How to generate feedback information of the receiver. 17. The channel quality of claim 16, wherein the channel quality of the group antenna is

Is calculated as remind

Denotes a rank,

Denotes the quality of the residual group antenna 'm' in the transmission BF scheme,

The method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system, characterized in that the quality of the residual group antenna 'm' is represented by a transmission SIC scheme. The method of claim 25, wherein

Is '1', the channel quality of the group antenna 'm' applied to a single user transmission is

Is calculated by

H is a matrix representing a channel in which the transmitter antennas and the receiver are wirelessly connected in a matrix, I is an index of an antenna group, and SNR is a signal-to-noise ratio receiver. To generate feedback information The method of claim 25, wherein

Is '2', the channel quality of the group antenna m applied to a single user transmission is

Is calculated by

H is a matrix representing a channel in which the transmitter antennas and the receiver are wirelessly connected in a matrix, I is an index of an antenna group, and SNR is a signal-to-noise ratio receiver. To generate feedback information 27. The method of claim 26, wherein the data rate of channel quality of the residual group antenna applied to the single user transmission is

Is calculated by

A method for generating feedback information of a receiver in a multi-user multi-transmit / receive antenna system indicating an index of a group antenna having a maximum channel quality in a transmission BF scheme. The data rate of the channel quality of the residual group antenna to be applied to the multi-user transmission is

Is calculated by

Denotes the index of the group antenna with the highest channel quality,

The method for generating feedback information of a receiver in a multi-user multiple transmit / receive antenna system indicating an index of a group antenna having a maximum channel quality in a transmit GSIC scheme. A quality measuring unit measuring an index of a group antenna having a maximum channel quality or capacity and a maximum capacity of the group antenna by using pilot signals received from a plurality of antennas included in a transmitter; A detector for detecting a rank value indicating a transmission antenna selection or a reception interference cancellation mode and an additional quality value for supporting a mode corresponding to the rank value; A multiple receiver for multiple reception of multiple streams transmitted from the detector; And And a decoding and demodulation unit for decoding and demodulating the multiple received streams. The method of claim 30, wherein the detection unit After the group antenna having the minimum quality value is turned off by using a beamforming (BF) technique, an additional quality is measured to support a mode corresponding to the rank, and the group is processed using a successive interference cancellation (SIC) technique. A receiver for generating feedback information in a multi-user multiple transmit / receive antenna system for measuring channel quality of an antenna. The method of claim 30, wherein the quality measuring unit Feedback information is generated in a multi-user multi-transmit / receive antenna system generating feedback information including the index of the group antenna having the maximum channel quality, the maximum quality value of the group antenna, the additional quality value, and rank information and transmitting the feedback information to the transmitter. To produce the receiver. 31. The method of claim 30, wherein the channel quality of each group antenna (eg m) is

Is calculated by

Denotes a channel in which the group antennas of the transmitter and the receiver are wirelessly connected in a matrix, I is an index of an antenna group, and SNR is a signal-to-noise ratio. receiving set. 31. The method of claim 30, wherein the additional quality is

Is calculated by the above

Denotes a rank,

Denotes the quality of the residual group antenna 'm' in the transmission BF scheme,

The receiver for generating feedback information in a multi-user multi-receive antenna system, characterized in that the quality of the residual group antenna 'm' by the transmission SIC method. 35. The method of claim 34, wherein

Is '1', the channel quality of the group antenna 'm' applied to a single user transmission is

Is calculated by

Is,

Denotes a channel in which the group antennas of the transmitter and the receiver are wirelessly connected in a matrix, I is an index of an antenna group, and SNR is a signal-to-noise ratio for generating feedback information in a multi-user multiple transmit / receive antenna system. receiving set. 35. The method of claim 34, wherein

Is '2', the channel quality of the group antenna 'm' applied in the multi-user mode is

Is calculated by

Where h is a matrix representing a channel in which the transmitter antennas and the receiver are wirelessly connected in a matrix, I is an index of an antenna group, and SNR is a signal-to-noise ratio. Receiver generating information. 36. The method of claim 35, wherein the data rate of channel quality of the residual group antenna applied to the single user transmission is

Is calculated by

The receiver for generating feedback information in a multi-user multi-receive antenna system representing the index of the group antenna having the maximum channel quality in the transmission BF scheme. 37. The method of claim 36, wherein the data rate of channel quality of the residual group antenna applied to the multi-user transmission is

Is calculated by

Denotes the index of the group antenna having the maximum channel quality,

The receiver for generating feedback information in a multi-user multi-receive antenna system indicating the index of the group antenna having the maximum channel quality in the transmission GSIC scheme.

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