KR20080093319A - Method of controlling sounding signal transmission in broadband wireless access system - Google Patents

Abstract

A method for controlling transmission of a sounding signal in a broadband wireless access system is provided to efficiently control transmission of the sounding signal transmitted from a terminal for channel estimation at a base station, and to prevent power consumption caused by transmission of unnecessary sounding signals and to enhance a beam forming gain if necessary by controlling a beam forming update operation or a channel estimation procedure via a network. A method for controlling transmission of a sounding signal in a broadband wireless access system includes the following several steps. A BS(Base Station) sends a sounding signal transmission command to a terminal via an uplink map on a frame(S11). The terminal sends a sounding signal according to control information related to the sounding signal transmission included in the sounding signal transmission command via a sounding area on an uplink subframe allocated by the BS(S12). The BS estimates a downlink channel state with respect to the terminal by using the sounding signal received from the terminal, controls a multi-antenna for data transmission according to the estimated channel state, and sends downlink data for the terminal via the multi-antenna(S13). The steps S12 and S13 are repeated according to a sounding signal transmission cycle(S14-S16). The terminal sends sounding control information to the BS in case that it determines that a sounding signal transmission scheme has to be changed according to situations while sending the sounding signal according to the control information transmitted from the BS(S17). The BS allows the terminal to stop sending the sounding signal via the uplink sounding command in case that the BS determines that a current beam forming gain need not be changed(S18). The BS sends downlink data to the terminal via the multi-antenna which is set for having a beam forming gain determined according to the sounding signal finally sent by the terminal(S19-S21).

Description

Method of controlling sounding signal transmission in broadband wireless access system

1 is a process flow diagram according to an embodiment of the present invention.

2 shows an uplink and downlink frame structure for explaining an embodiment of the present invention.

3 illustrates an example of a structure of a feedback header according to an embodiment of the present invention.

4 illustrates another example of a feedback header structure according to an embodiment of the present invention.

5 is a process flow diagram according to another embodiment of the present invention.

The present invention relates to a broadband wireless access system, and more particularly, to a sounding signal transmission control method in a broadband wireless access system.

In a communication system, an antenna refers to a port to which RF (Radio Frequency) energy is transmitted, from which a signal is transmitted from the transmitter to the outside or a signal is received from the outside to the receiver. In the 3rd and 4th generation wireless communication systems, not only voice calls but also multimedia data including image and video data must be transmitted and received with high reliability. In order to provide multimedia services, it is required to occupy much wider bandwidth per subscriber than the present, and the allocated frequency of the entire system is limited, so the communication capacity is inevitably reduced. One of the technologies that can solve this problem is the smart antenna technology.

Smart antenna system refers to an intelligent antenna system that can automatically change the radiation beam pattern in response to a given channel environment. An antenna element in which a plurality of adaptive array antenna elements are arranged in a linear, planar or circular form It is based on a beam forming technique that adaptively combines the transmitted or received signals from these devices. With smart antenna systems, both capacity and communication reliability can be achieved by providing optimal wireless access by eliminating interference and noise without altering the overall structure of the system, including network and signal formats. In other words, the smart antenna system is a technology that can reduce the interference signal, thereby increasing the communication capacity and quality by setting the optimal beam to each subscriber in the cell of the wireless communication system. The smart antenna system is an integrated system in which an RF device modem and a beam forming module are integrated, and is recognized as a core technology of the next generation wireless communication system.

The smart antenna system according to the prior art has the following configuration and function.

1) Antenna Array: It is composed of multiple antennas to generate the desired antenna beam pattern. As the number of antennas increases, the beam pattern is narrowed and performance is improved. However, 4 to 12 are usually used in consideration of system complexity.

2) RF Transciver: It is used equally to the number of array antennas and consists of up / down converter RF / IF module for RF input / output signals inputted from each array antenna.

3) Beamformer: A module that performs beamforming in the desired user direction, where various adaptive algorithms are used to calculate weight vectors for beamforming.

4) RF Calibration: Minor differences in the characteristics of each array antenna element in a multi-channel receiver and errors in amplitude and phase between RF channel transceivers can cause degradation of the beamformer's performance. Therefore, it is necessary to compensate for the characteristic difference of each antenna element and to correct the amplitude and phase difference of the RF channel transceiver between array antennas.

In the smart antenna system used in the wireless communication system according to the prior art, the base station estimates the channel state for each terminal based on a reference signal transmitted from each terminal, and the beamforming gain based on the estimated channel state (beamforming gain) is calculated. The base station forms an antenna beam for each terminal by applying the calculated beamforming gain and transmits downlink data through the base station. An example of the reference signal may be a sounding signal used in a broadband wireless access system.

As described above, the symmetry between the uplink and the downlink is assumed, and the base station estimates the state of the downlink channel from the reference signal transmitted by each terminal through the uplink, and accordingly, the antenna beam for each terminal is estimated. Form. By the way, it may be reasonable to assume that the channel states of the uplink and the downlink are symmetrical, but the interference state is not that the uplink and the downlink are symmetrical. Accordingly, the base station can estimate the downlink channel state based on the uplink reference signal transmitted from the terminal using uplink downlink symmetry, but cannot accurately estimate the interference state. In particular, in a channel environment in which the amount of interference varies greatly, the terminal may determine the overall downlink channel state more accurately than the base station.

According to the prior art as described above, it is difficult for the base station to accurately determine the downlink channel state, and beamforming according to the incorrectly estimated channel state may not guarantee an optimal result. In addition, even if the terminal does not perform any control operation related to beamforming other than transmitting the reference signal to the base station periodically or once at the command of the base station, and thus does not need to update the beamforming gain. If the power of the terminal is wasted by periodically transmitting the reference signal or if the beamforming gain update is required through the reference signal transmission, the reference signal cannot be transmitted without the command of the base station, thereby failing to obtain the required beamforming gain.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a method that can enable the efficient application of the smart antenna technique used in the wireless communication system.

Another object of the present invention is to provide a method for allowing a terminal to control a beamforming gain update operation of a base station by adapting to a change in a wireless environment.

Still another object of the present invention is to provide a method for controlling transmission of a sounding signal transmitted from a terminal for channel estimation at a base station.

In one aspect of the present invention, a sounding signal transmission control method according to the present invention, in the terminal of a broadband wireless access system using multiple antennas to transmit the sounding signal (sounding signal) used by the base station to control the multiple antennas A control method comprising: receiving first control information related to transmission of a sounding signal from the base station, transmitting a sounding signal according to the first control information to the base station, and sounding to the base station And transmitting second control information related to signal transmission, and transmitting a sounding signal to the base station according to the second control information.

As another aspect of the present invention, the sounding signal transmission control method according to the present invention, in a terminal of a broadband wireless access system using multiple antennas in a method for controlling the transmission of the sounding signal used to control the multiple antennas by the base station Receiving a first control information associated with the transmission of a sounding signal from the base station, transmitting a sounding signal according to the first control information to the base station, and stopping the sounding signal transmission to the base station Transmitting second control information requesting a signal; and receiving downlink data transmitted through multiple antennas controlled by the base station based on a sounding signal transmitted according to the first control information. do.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention, a method for controlling the transmission of the sounding signal used by the base station to control the multiple antennas in a terminal of a broadband wireless access system using multiple antennas Receiving downlink data transmitted through the multi-antenna from the base station, transmitting the control information associated with the transmission of the sounding signal to the base station, the sounding signal according to the control information to the base station And transmitting downlink data transmitted through the multiple antennas controlled based on the sounding signal at the base station.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention is a method for controlling the transmission of sounding signals used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas. Transmitting first control information related to transmission of a sounding signal to a specific terminal; receiving a sounding signal transmitted according to the first control information from the terminal; and transmitting a sounding signal from the terminal. And receiving second control information related to the control signal and receiving a sounding signal transmitted according to the second control information from the terminal.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention, a method for controlling the transmission of the sounding signal used to control the multiple antennas in the base station in the terminal of the broadband wireless access system using multiple antennas The method of claim 1, further comprising: transmitting first control information related to transmission of a sounding signal to a specific terminal, receiving a sounding signal transmitted according to the first control information from the terminal, and a sounding signal from the terminal Receiving second control information requesting to stop transmission and transmitting downlink data transmitted through the multiple antennas controlled based on the sounding signal transmitted according to the first control information to the terminal; It can be configured to include.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention is a method for controlling the transmission of sounding signals used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas. Transmitting downlink data to the terminal through multiple antennas; receiving control information related to transmission of a sounding signal from the terminal; and transmitting a sounding signal transmitted according to the control information from the terminal. And transmitting downlink data to the terminal through the multiple antennas controlled based on the sounding signal.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention, a method for controlling the transmission of the sounding signal used by the base station to control the multiple antennas in a terminal of a broadband wireless access system using multiple antennas Receiving a first control information associated with the transmission of the sounding signal from the base station, transmitting a sounding signal according to the first control information to the base station, and the sounding signal to the base station Transmitting second control information related to transmission, receiving third control information related to transmission of a sounding signal including contents of the second control information from the base station, and performing the third control to the base station. And transmitting the sounding signal according to the information.

As another aspect of the present invention, a sounding signal transmission control method according to the present invention is a method for controlling the transmission of sounding signals used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas. Transmitting first control information related to transmission of a sounding signal to a specific terminal; receiving a sounding signal transmitted according to the first control information from the terminal; and transmitting a sounding signal from the terminal. Receiving second control information associated with the second control information; transmitting third control information related to a sounding signal including content of the second control information to the terminal; and according to the third control information from the terminal. And receiving the transmitted sounding signal.

As another aspect of the present invention, the feedback header structure according to the present invention is a feedback used to control the transmission of sounding signals used by a base station to control multiple antennas in a terminal of a broadband wireless access system using multiple antennas. In the header structure, at least one first field indicating that the feedback header includes sounding control information for controlling transmission of the sounding signal, and at least one second including the sounding control information. It may be configured to include a field.

The construction, operation and other features of the present invention will be readily understood by the embodiments of the present invention described below with reference to the accompanying drawings. The embodiments described below are embodiments in which the technical features of the present invention are applied to a broadband wireless access system, and the matters not described in this document are "IEEE Standard for Local and" which is a technical standard for a broadband wireless access system. metropolitan area networks, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems, Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, 28 February 2006.

1 is a flowchart illustrating a procedure according to an embodiment of the present invention, Figure 2 illustrates an uplink and downlink frame structure for explaining an embodiment of the present invention.

Referring to FIGS. 1 and 2, a base station (BS) transmits a UL_sounding_command_IE to a mobile station (MS) through an uplink map (UL-MAP) on a frame to transmit a sounding signal or sounding waverform. ) Send a transfer command [S11]. The UL_sounding_command_IE includes control information related to sounding signal transmission by the terminal. The control information may include a transmission period of a sounding signal, a number of symbols by sounding signal transmission, a terminal discrimination method, a transmission power allocation method of sounding signals, a subchannel allocation method for sounding transmission, and the like. Other details related to sounding signal transmission may be referred to 8.4.6.2.7.1 (Channel Sounding) section of page 547 in the technical standard document of the broadband wireless access system, and in particular, an example of the data format of the UL_sounding_command_IE. See Table 315d.

The uplink map on the frame of FIG. 2 includes PAPR_Reduction_Safty_Sounding_Zone_Allocation_IE. The PAPR_Reduction_Safty_Sounding_Zone_Allocation_IE includes an indicator indicating whether to include a sounding zone for transmitting a sounding signal by the terminal within an uplink subframe among the corresponding frames and allocation information indicating the location of the sounding zone. . The sounding region is a time-frequency region in which the terminal transmits a sounding signal, and is configured by one or more symbols on a time axis and one or more subchannels on a frequency axis. Therefore, the sounding region allocation information may be represented by a symbol offset, a subchannel offset, a number of symbols, and a number of subchannels. The sounding region is usually located at the end of the uplink subframe (see FIG. 2). An example of the data format of the PAPR_Reduction_Safty_Sounding_Zone_Allocation_IE may refer to Table 289 in the technical standard document of the broadband wireless access system.

A plurality of terminals may transmit a sounding signal to the base station through the sounding area. There are two methods for transmitting a sounding signal by a plurality of terminals through one sounding area. First, a plurality of terminals transmit a sounding signal using the entire band included in the sounding region, that is, the entire subcarriers, but the phase difference of the sounding signals transmitted for each terminal allows the base station to distinguish each terminal. Cyclic shift separability. At this time, the phase difference to be applied to each terminal, the base station informs each terminal through the UL_sounding_command_IE. Secondly, each terminal transmits a sounding signal using subcarriers allocated so as not to overlap each other without using the entire subcarriers in the sounding region (decimation separability). For example, the i-th terminal may transmit a sounding signal in every (10n + m) th subchannel, and n and m may be differently allocated to each terminal. n, m informs each terminal of the base station through UL_sounding_command_IE.

The terminal transmits a sounding signal according to the information included in the UL_sounding_command_IE and the PAPR_Reduction_Safty_Sounding_Zone_Allocation_IE [S12]. That is, the sounding signal is transmitted according to the control information related to the sounding signal transmission included in the UL_sounding_command_IE through the sounding region ('A' of FIG. 2) on the uplink subframe allocated by the base station. For example, when a sounding signal transmission period and a transmission power allocation method are included in the control information related to the sounding signal transmission, the terminal transmits a sounding signal to the base station according to the corresponding transmission power allocation method for each period. do.

The base station estimates a downlink channel state for the terminal using the sounding signal received from the terminal, and controls downlink data for the terminal by controlling multiple antennas for data transmission according to the estimated channel state. Send [S13]. For example, the base station calculates a beamforming gain using the sounding signal received from the terminal, generates a beam by applying the calculated beamforming gain to the multiple transmit antenna, and then uses the beam. And transmits downlink data for the terminal.

Steps S12 and S13 are repeatedly performed according to the sounding signal transmission period [S14 to S16].

If the terminal determines that it is necessary to change the transmission method of the sounding signal according to the situation while transmitting the sounding signal according to the control information transmitted from the base station [S17]. For example, if it is determined that it is sufficient to maintain the current beamforming gain according to the channel condition, the base station may be requested to stop the transmission of the sounding signal through the sounding control information. Alternatively, it may be requested to change any information included in the UL_sounding_command_IE, such as a transmission period or transmission power of a sounding signal.

In the embodiment of FIG. 1, the terminal transmits the sounding control information through a feedback header. 3 illustrates an example of a structure of a feedback header according to an embodiment of the present invention, and shows a 'Feedback content' field when 'Feedback type = 0000' indicating MIMO mode feedback in a feedback header. Modified to transmit the sounding control information.

In FIG. 3, a 'Feedback Type' field is a field indicating feedback contents to be delivered to the base station through the feedback header. For example, when the 'Feedback Type' field is set to '0000,' It indicates that downlink channel measurement (CQI) and information related to MIMO mode or sounding control information are transmitted. The details are shown in Table 1 below.

Feedback Type (binary) Feedback contents Descriptions 0000 MIMO feedback type (3bits) + feedback payload (6bits) CQI, MIMO feedback and UL sounding feedback. The definitions of MIMO feedback type (3bits) and the corresponding feedback payload (6bits) are the same as that defined in Table 302b and subclasses 8.4.5.4.10.4, 8.4.5.4.10.5, 8.4.5.4.10.6, 8.4.5.4. 10.7, 8.4.5.4.10.8, 8.4.5.4.10.9, 8.4.5.4.10.10 for the Enhanced Fast-feedback channel. If MIMO feedback type = 0b110 (UL sounding), feedback payload consists of periodicity (3 bits), Include additional feedback (2bits), and Num sounding symbols (3bits) defined in Table 315d.

In Table 1, when the 'Feedback type' is set to '0000' in the prior art, it indicates that the feedback content included in the feedback header is CQI or MIMO mode related information. In an embodiment of the present invention, the 'Feedback type' is' When set to '0000', the feedback content included in the feedback header indicates CQI / MIMO mode related information or sounding control information. For detailed information related to each other feedback type and the feedback content thereof, refer to Table 7i of the technical standard document of the broadband wireless access system.

The 'MIMO mode feedback' field is a field for specifically indicating the feedback content included in the feedback header among the CQI / MIMO mode related information or sounding control information when the 'Feedback Type' field is set to '0000'. . Table 2 describes the feedback contents according to the 'MIMO mode feedback' field setting value.

Syntax Size Notes MIMO mode feedback 3 bits 0b000 = Fast DL measurement / MIMO mode and permutation feedback 0b001 = Fast DL measurement / Antenna grouping 0b010 = Fast DL measurement / Antenna selection 0b011 = Quantized precoding weight feedback 0b100 = Index to precoding matrix in codebook 0b101 = Channel Matrix Information 0b110 = UL sounding REQ (Sounding control information) 0b111 = Reserved

In Table 2, when the 'MIMO mode feedback' field is set to '110', it means that the feedback header includes sounding control information as the feedback content, and when it is set to the remaining '000' to '101', CQI / MIMO This means that mode-related information is included.

In other words, in the embodiment of FIG. 3, when the 'Feedback Type' field is set to '0000' and the 'MIMO mode feedback' field is set to '110', the sounding control information as feedback content in the feedback header. Will be included. However, the embodiment of FIG. 3 is merely for convenience of understanding and may be modified in various ways to include the sounding control information using a conventional feedback header.

In FIG. 3, the 'Periodicity' field, the 'Include additional feedback' field, and the 'Num sounding symbols' field are fields including information that may be included in the sounding control information. However, even in this case, the information included in the three fields is only an example of configuring the sounding control information. If necessary, one of the three fields may not be included or other information may be included. Table 3 is for explaining the details of the three fields.

Syntax Size Descriptions Periodicity 3bits 0b000 = single command, not periodic, or terminate periodicity 0b001-0b111 repeat sounding once per r frames, where r = 2 ^ (n-1), where n is the decimal equivalent of the periodicity field. Include additional feedback 2 bits 0b00 = No additional feedback 0b01 = include channel coefficients (see 8.4.6.2.7.3) 0b10 = include received pilot coefficients 0b11 = include feedback message Num sounding symbols 3bits total number of sounding symbols being allocated, from 1 (0b000) to 2 ^ 3 = 8 (0b111)

In Table 3, the 'Periodicity' field includes information related to a transmission period of a sounding signal. For example, when set to '000', it may mean that the terminal requests to transmit a sounding signal to the base station aperiodically or singly (one time). As shown in FIG. 1, when the UE periodically transmits a sounding signal, the terminal stops transmitting the periodic sounding signal when the 'Periodicity' field is set to '000' and transmitted. When set to '001' to '111', it may indicate that the terminal transmits a sounding signal every 2 ^ (n-1) frames by changing a sounding signal transmission period. In this case, n is a decimal representation value of the setting value of the 'Periodicity' field.

The 'Include additional feedback' field is a field for informing whether the terminal additionally transmits other information that the terminal may transmit to inform the base station of channel information in addition to sounding signal transmission. When the terminal transmits the additional information to the base station, the base station may be used to determine the channel state by combining the information obtained from the received sounding signal and the additionally received information. For example, when the 'Include additional feedback' field is set to '00', this may indicate that only a sounding signal is to be transmitted without additional feedback. In this case, the sounding signal is a simple waveform in which no information is carried, and the base station receives the sounding signal and acquires necessary information by using physical characteristics of the received signal. For example, the base station receives a sounding signal and calculates a phase difference for each waveform arriving at each array antenna, or a plurality of base stations each receive a sounding signal of the same terminal to obtain a beamforming gain by a triangulation method. Can be calculated

When the 'Include additional feedback' field is set to '01', it indicates that the channel coefficients calculated by the terminal are additionally transmitted through the assigned sounding area. It may indicate that pilot coefficients will be transmitted. In this case, the information representing the channel coefficients and the pilot coefficients may be transmitted to the base station by being carried in a sounding signal by a modulation method.

When the 'Include additional feedback' field is set to '11', this may indicate that a feedback message is additionally transmitted. That is, it indicates that additional information is additionally transmitted by transmitting a separate feedback message by using a separate resource in addition to the allocated sounding area.

The 'Num sounding symbols' field is a field indicating the number of symbols (wireless section resources) used by the terminal to transmit a sounding signal.

4 illustrates an example of a structure of a feedback header according to an embodiment of the present invention, in which a value of a 'Feedback type' field for transmitting sounding control information through a feedback header is newly defined. That is, in the structure of the conventional feedback header, the 'Feedback type' field is defined from '0000' to '1101' (see Table 7i in the technical standard document of the broadband wireless access system), as shown in Table 4 below. Likewise, any one of '1111' to '1111' values which are not defined yet may be selected and used for the purpose of sounding control information according to an embodiment of the present invention. In the example of FIG. 4, '1110' is used. In other words, when the 'Feedback type' field is set to '1110', it means that the feedback content included in the feedback header is related to the sounding control information.

Feedback Type (binary) Feedback contents Descriptions 1110 UL sounding REQ: periodicity (3 bits) + Include additional feedback (2bits) + Num sounding symbols (3bits) The definitions of periodicity (3 bits), Include additional feedback (2bits), and Num sounding symbols (3bits) are the same as that defined in Table 315d. 1111 Reserved for future use -

In FIG. 4, the sounding control information is included in a 'Periodicity' field, an 'Include additional feedback' field, and a 'Num sounding symbols' field. For detailed description of the three fields, refer to Table 2 and a description thereof.

In the feedback header structure of FIGS. 3 and 4, a portion of which feedback content may be included is 16 bits. However, if the information to be included as the feedback content exceeds 16 bits, the feedback content may be further added to the CID field. That is, the feedback content of up to 32 bits can be included without including the CID in the feedback header. Therefore, in the embodiments of FIGS. 3 and 4, the 'Periodicity' field, the 'Include additional feedback' field, and the 'Num sounding symbols' field are included only as examples for transmitting sounding control information. Accordingly, various forms of sounding control information may be configured by using the entire 32 bits.

Referring back to FIG. 1, the procedure after the terminal transmits the sounding control information to the base station may vary depending on the content of the sounding control information. For example, when the terminal determines that it is not necessary to change the current beamforming gain, and requests to stop transmitting the sounding signal through the sounding control information, the base station transmits a sounding signal to the terminal through UL_sounding_command_IE. Can be stopped [S18]. Thereafter, the base station transmits downlink data to the terminal through multiple antennas configured to have a beamforming gain determined according to a sounding signal last transmitted by the terminal [S19 to S21].

As another example, when the terminal requests the base station to change the transmission period of the sounding signal through the sounding control information, the base station reflects the sounding signal transmission period requested by the terminal through the UL_sounding_command_IE to the terminal Transmit control information for signal transmission. Furthermore, the UL_sounding_command_IE may further include content of the sounding control information received from the terminal. If the base station does not allow sounding control information received from the terminal, the base station may transmit control information related to sounding signal transmission different from the sounding control information to the terminal through the UL_sounding_command_IE. .

Thereafter, the terminal periodically transmits a sounding signal to the base station according to the control information, and the base station calculates a beamforming gain using the sounding signal received from the terminal and sets the multiple antennas accordingly. Downlink data is transmitted to the terminal. In FIG. 2, the portion 'B' means a data burst in which downlink data is transmitted for the terminal. The terminal can determine the location of the data burst transmitted to the user through the downlink map DL_MAP included in the downlink subframe. If the information indicating that the additional information is included in the 'Include additional feedback' field of the feedback header transmitted by the terminal, the base station uses the sounding signal received from the terminal and the additional information to the beamforming gain Calculate.

5 is a process flow diagram according to another embodiment of the present invention. In the embodiment of FIG. 5, the terminal requests transmission of the sounding signal to the base station according to a change in channel condition while the base station transmits downlink data to have a constant beamforming gain without receiving the sounding signal from the terminal. One example.

Referring to FIG. 5, the base station transmits downlink data to the terminal by setting multiple antennas to have a constant beamforming gain [S51 ~ S52]. The terminal, when determined to be necessary, transmits sounding control information to the base station to request transmission of a sounding signal [S53]. The sounding control information may be included in a feedback header. The structure of the feedback header including the sounding control information may be based on the example of FIG. 3 or 4. That is, the terminal includes feedback control information such as information related to a sounding signal transmission period, indication information on whether additional information is included, number of symbols for sounding signal transmission, and the like in the feedback header as shown in FIG. 3 or 4. The transmission of the sounding signal can be requested by transmitting to the base station. Details of the feedback header and sounding control information may be referred to the parts described through the embodiment of FIG. 1.

The base station configures and transmits a UL_sounding_command_IE according to sounding control information received from the terminal, and transmits control information for sounding signal transmission to the terminal [S54]. The terminal transmits a sounding signal to the base station according to the control information included in the UL_sounding_command_IE [S55]. The base station calculates a beamforming gain using the sounding signal received from the terminal, and transmits downlink data for the terminal by applying the calculated beamforming gain to the multi-transmission antenna [S56]. Transmission of the sounding signal by the terminal and downlink data transmission by the base station may be repeated periodically [S57 ~ S59].

The terminology used herein may be replaced with other terms having the same meaning. For example, a terminal may be replaced with a mobile terminal, a communication terminal, a user equipment or a device, and the like, and a base station may be replaced with a term such as a fixed station. In the above detailed description, the process of performing communication between the terminal and the base station has been described mainly for the convenience of description of the present invention and its embodiments. However, the base station is used to mean a device representing the network. The specific operation described above may be performed by a network node or an entity.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

According to the present invention has the following effects.

First, it is possible to efficiently apply the smart antenna technique used in the wireless communication system.

Second, the terminal may control the beamforming gain update operation of the base station by adapting to a change in the wireless environment.

Third, it is possible to efficiently control the transmission of the sounding signal transmitted from the terminal for channel estimation at the base station.

Fourth, it is possible to control the beamforming update operation or the channel estimation process by the network from the viewpoint of the terminal to prevent power consumption due to unnecessary sounding signal transmission, and to improve the beamforming gain as necessary.

Claims (25)

A method of controlling transmission of a sounding signal used by a base station to control multiple antennas in a terminal of a broadband wireless access system using multiple antennas, the method comprising: Receiving first control information related to transmission of a sounding signal from the base station; Transmitting a sounding signal to the base station according to the first control information; Transmitting second control information related to transmission of a sounding signal to the base station; And And transmitting a sounding signal according to the second control information to the base station. A method of controlling transmission of sounding signals used by a base station to control multiple antennas in a terminal of a broadband wireless access system using multiple antennas, the method comprising: Receiving first control information related to transmission of a sounding signal from the base station; Transmitting a sounding signal to the base station according to the first control information; Transmitting second control information requesting to stop transmitting a sounding signal to the base station; And And receiving, by the base station, downlink data transmitted through multiple antennas controlled based on the sounding signal transmitted according to the first control information. The method according to claim 1 or 2, And receiving third control information related to sounding signal transmission in which the content of the second control information is reflected from the base station. The method of claim 1, And the second control information includes information related to a transmission period of a sounding signal. The method of claim 4, wherein And the second control information further includes indication information indicating whether there is additional information transmitted in addition to the sounding signal. The method of claim 5, And the second control information further includes information related to a radio resource to be used for transmitting a sounding signal. The method according to any one of claims 1 to 6, The second control information is included in the feedback header (feedback header) characterized in that the transmission, sounding signal transmission control method. The method of claim 6, And the information related to the radio resource is a number of symbols to be used for transmitting the sounding signal. A method of controlling transmission of sounding signals used by a base station to control multiple antennas in a terminal of a broadband wireless access system using multiple antennas, the method comprising: Receiving downlink data transmitted through the multiple antennas from the base station; Transmitting control information related to transmission of a sounding signal to the base station; Transmitting a sounding signal to the base station according to the control information; And And receiving downlink data transmitted through the multiple antennas controlled based on the sounding signal at the base station. The method of claim 9, And the control information includes information related to a transmission period of a sounding signal. The method of claim 10, And the control information further includes indication information indicating whether there is additional information transmitted in addition to the sounding signal. The method of claim 11, And the control information further comprises information related to a radio resource to be used for transmitting the sounding signal. The method according to any one of claims 9 to 12, The control information is included in the feedback header, characterized in that the transmission, sounding signal transmission control method. The method of claim 12, And the information related to the radio resource is the number of symbols to be used for transmitting the sounding signal. A method of controlling transmission of a sounding signal used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas, the method comprising: Transmitting first control information related to transmission of a sounding signal to a specific terminal; Receiving a sounding signal transmitted according to the first control information from the terminal; Receiving second control information related to transmission of a sounding signal from the terminal; And Receiving a sounding signal transmitted according to the second control information from the terminal. A method of controlling transmission of sounding signals used to control multiple antennas at a base station in a terminal of a broadband wireless access system using multiple antennas, Transmitting first control information related to transmission of a sounding signal to a specific terminal; Receiving a sounding signal transmitted according to the first control information from the terminal; Receiving second control information for requesting to stop sounding signal transmission from the terminal; And And transmitting downlink data transmitted through the multiple antennas controlled based on the sounding signal transmitted according to the first control information to the terminal. A method of controlling transmission of a sounding signal used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas, the method comprising: Transmitting downlink data through the multiple antennas to the terminal; Receiving control information related to transmission of a sounding signal from the terminal; Transmitting a sounding signal transmitted according to the control information from the terminal; And And transmitting downlink data to the terminal through the controlled multiple antennas based on the sounding signal. A method of controlling transmission of sounding signals used by a base station to control multiple antennas in a terminal of a broadband wireless access system using multiple antennas, the method comprising: Receiving first control information related to transmission of a sounding signal from the base station; Transmitting a sounding signal to the base station according to the first control information; Transmitting second control information related to transmission of a sounding signal to the base station; Receiving third control information related to transmission of a sounding signal including contents of the second control information from the base station; And And transmitting a sounding signal according to the third control information to the base station. A method of controlling transmission of a sounding signal used to control multiple antennas in a base station of a broadband wireless access system using multiple antennas, the method comprising: Transmitting first control information related to transmission of a sounding signal to a specific terminal; Receiving a sounding signal transmitted according to the first control information from the terminal; Receiving second control information related to transmission of a sounding signal from the terminal; Transmitting third control information related to a sounding signal including contents of the second control information to the terminal; And Receiving a sounding signal transmitted according to the third control information from the terminal. In the structure of the feedback header used to control the transmission of the sounding signal used by the base station to control the multiple antenna in the terminal of a broadband wireless access system using multiple antennas, At least one first field indicating that the feedback header includes sounding control information for controlling transmission of the sounding signal; And And at least one second field containing the sounding control information. The method of claim 20, wherein the at least one first field is A 'Feedback type' field indicating that channel quality information (CQI), multiple input / output antenna (MIMO), or sounding control information is included as feedback content included in the feedback header; And a 'MIMO mode feedback' field indicating that sounding control information is included as feedback content included in the feedback header. The method of claim 20, wherein the at least one first field is And a 'Feedback type' field indicating that sounding control information is included as feedback content included in the feedback header. The method of claim 21 or 22, And the at least one second field includes a third field including information related to a transmission period of a sounding signal. The method of claim 23, wherein And the at least one second field further comprises a fourth field including indication information indicating whether there is additional information transmitted in addition to a sounding signal. The method of claim 24, And the at least one second field further comprises a fifth field containing information relating to a radio resource to be used for transmitting a sounding signal.

Images