KR20110013313A - Method and apparatus of transmitting feedback in wireless communication system - Google Patents

Abstract

PURPOSE: A feedback transmission method in wireless communication system and an apparatus thereof are provided to measure the feedback information such as CQI(Channel Quality Indictor) accurately by feedback of sub band index. CONSTITUTION: At least one sub band is selected out of a plurality of sub bands comprising the sub bands group(S100). The feedback information measured for the one sub band is transmitted(S110). The feedback information comprises the index of the sub band. The sub band is selected in consideration of the frequency partition or the resource mapping of the plurality of sub bands.

Description

Feedback transmission method and device in wireless communication system {METHOD AND APPARATUS OF TRANSMITTING FEEDBACK IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting feedback in a wireless communication system.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16e standard is the sixth standard for the International Mobile Telecommunications (IMT-2000) in the ITU-Radiocommunication Sector (ITU-R) under the International Telecommunication Union (ITU) in 2007. It was adopted under the name OFDMA TDD '. ITU-R is preparing the IMT-Advanced system as the next generation 4G mobile communication standard after IMT-2000. The IEEE 802.16 Working Group (WG) decided to implement the IEEE 802.16m project in late 2006 with the aim of creating an amendment specification for the existing IEEE 802.16e as a standard for IMT-Advanced systems. As can be seen from the above objectives, the IEEE 802.16m standard implies two aspects: the past continuity of modification of the IEEE 802.16e standard and the future continuity of the specification for next generation IMT-Advanced systems. Therefore, the IEEE 802.16m standard is required to satisfy all the advanced requirements for the IMT-Advanced system while maintaining compatibility with the Mobile WiMAX system based on the IEEE 802.16e standard.

Multiple input multiple output (MIMO) may be considered as a technology for supporting reliable high speed data service. MIMO technology uses multiple transmit antennas and multiple receive antennas to improve data transmission and reception efficiency. MIMO techniques include spatial multiplexing, transmit diversity, beamforming, and the like. The MIMO channel matrix according to the number of receive antennas and the number of transmit antennas may be decomposed into a plurality of independent channels. Each independent channel is called a layer or stream. The number of layers is called rank.

The terminal may transmit the feedback through the uplink. The feedback may include channel information necessary for data transmission. The base station may schedule radio resources using the feedback received from the terminal and transmit data. The closed loop method is a method of transmitting data by compensating channel information included in feedback from a terminal, and the open loop method is performed by compensating data without compensating channel information included in feedback from a terminal. It is a transmission method. The feedback may not be transmitted in the open loop manner, and even when transmitted, the base station may not use the channel information included in the feedback. In general, in a wireless communication system, the open loop method may be applied in a channel environment for a terminal moving at high speed, and the closed loop method may be applied in a channel environment for a terminal moving at a low speed. Since the channel for the mobile terminal moving at a high speed is difficult to trust the channel information including the feedback, the open loop scheme is applied. Since the channel environment for the mobile station moving at a low speed is relatively small, the channel information including the feedback is reliable and less sensitive to delay, so that the closed loop method can be applied.

The uplink control channel can carry various kinds of feedback information. The feedback information may include channel quality indicator (CQI), MIMO feedback, acknowledgment / non-acknowledgement (ACK / NACK), uplink synchronization signal, bandwidth request, and the like. The feedback information may be transmitted in various combinations according to a channel environment or a predetermined configuration. In addition, feedback information for the entire bandwidth may be measured and fed back, or feedback information for some subbands of the bandwidth may be measured and fed back. When feedback information for some subbands is measured, the indexes of the corresponding subbands may also be fed back.

There is no specific method for feeding back a subband index in an IEEE 802.16m system. Therefore, a method for efficiently feeding back the subband index needs to be proposed.

An object of the present invention is to provide a method and apparatus for transmitting feedback in a wireless communication system.

In one aspect, a method for transmitting feedback in a wireless communication system is provided. The feedback transmission method includes selecting at least one subband among a plurality of subbands constituting a subband set, and transmitting feedback information measured for the at least one subband, wherein the feedback The information includes an index of the at least one subband, and the at least one subband is selected in consideration of a frequency partition or resource mapping of the plurality of subbands. The at least one subband is selected from the entire set of subbands, and the at least one subband may belong to the selected specific frequency partition. The information on the specific frequency partition may be signaled by a feedback allocation Advanced-MAP (A-MAP) Information Element (IE), or the specific frequency partition may be selected by the terminal. Information on the specific frequency partition may be fed back to the base station by primary fast feedback channel (PFBCH) encoding type 1. The at least one subband may be selected from a set of subbands belonging to a specific frequency partition. The at least one subband is selected from the entire subband set, and the at least one subband may belong to a subband set mapped to a CLRU (Contiguous Logical Resource Unit). The at least one subband may be selected from a set of subbands mapped to the CLRU. The feedback information may be transmitted to a base station through a primary fast feedback channel (PFBCH) or a secondary fast feedback channel (SFBCH).

In another aspect, an apparatus for transmitting feedback in a wireless communication system is provided. The apparatus for transmitting feedback transmits an RF unit for transmitting feedback information measured for at least one subband, and the at least one subband from among a plurality of subbands constituting a subband set. Wherein the feedback information includes an index of the at least one subband, wherein the at least one subband is selected in consideration of a frequency partition or resource mapping of the plurality of subbands. The at least one subband is selected from the entire subband set, and the at least one subband may belong to the selected specific frequency partition. The at least one subband may be selected from a set of subbands belonging to a specific frequency partition. Alternatively, the at least one subband may be selected from the entire subband set, and the at least one subband may belong to a subband set mapped to the CLRU. The at least one subband may be selected from a set of subbands mapped to the CLRU. The feedback information may be transmitted to the base station through PFBCH or SFBCH.

By feedbacking the subband index in consideration of the bandwidth, the transmit power level of the frequency partition, and the resource mapping of the subbands, feedback information such as channel quality indictor (CQI) can be accurately measured and efficiently. The subband index can be fed back.

1 shows a wireless communication system.
2 shows an example of a frame structure.
3 shows an example of an uplink resource structure.
4 shows an example of a method of dividing an entire frequency band into a plurality of frequency partitions.
5 shows an example of a cellular system in which the FFR technique is used.
6 shows an example of a subband partitioning process.
7 is an exemplary diagram illustrating a frequency band.
8 shows an example of an uplink resource used for PFBCH.
9 is a block diagram illustrating a process of mapping feedback information to a PFBCH.
10 is a block diagram illustrating a process in which feedback information is mapped to SFBCH.
11 is an embodiment of a proposed feedback transmission method.
12 is a block diagram illustrating a base station and a terminal in which an embodiment of the present invention is implemented.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), or the like. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using Evolved-UMTS Terrestrial Radio Access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted. LTE-A (Advanced) is the evolution of 3GPP LTE.

For clarity, the following description focuses on IEEE 802.16m, but the technical spirit of the present invention is not limited thereto.

1 illustrates a wireless communication system.

The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides a communication service for a particular geographic area (generally called a cell) 15a, 15b, 15c. The cell may again be divided into multiple regions (referred to as sectors). The UE 12 may be fixed or mobile, and may have a mobile station (MS), a mobile terminal (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a PDA ( Other terms may be referred to as a personal digital assistant, a wireless modem, a handheld device, etc. The base station 11 generally refers to a fixed station that communicates with the terminal 12. It may be called other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point.

The UE belongs to one cell, and the cell to which the UE belongs is called a serving cell. A base station that provides a communication service for a serving cell is called a serving BS. Since the wireless communication system is a cellular system, there are other cells adjacent to the serving cell. Another cell adjacent to the serving cell is called a neighbor cell. A base station that provides communication service for a neighbor cell is called a neighbor BS. The serving cell and the neighbor cell are relatively determined based on the terminal.

This technique can be used for downlink or uplink. In general, downlink means communication from the base station 11 to the terminal 12, and uplink means communication from the terminal 12 to the base station 11. In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11.

2 shows an example of a frame structure.

Referring to FIG. 2, a superframe (SF) includes a superframe header (SFH) and four frames (frames, F0, F1, F2, and F3). Each frame in the superframe may have the same length. The size of each superframe is 20ms and the size of each frame is illustrated as 5ms, but is not limited thereto. The length of the superframe, the number of frames included in the superframe, the number of subframes included in the frame, and the like may be variously changed. The number of subframes included in the frame may be variously changed according to the channel bandwidth and the length of the cyclic prefix (CP).

One frame includes a plurality of subframes (subframe, SF0, SF1, SF2, SF3, SF4, SF5, SF6, SF7). Each subframe may be used for uplink or downlink transmission. One subframe includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols or an orthogonal frequency division multiple access (OFDMA) in a time domain, and includes a plurality of subcarriers in the frequency domain. do. The OFDM symbol is used to represent one symbol period, and may be called another name such as an OFDMA symbol or an SC-FDMA symbol according to a multiple access scheme. The subframe may be composed of 5, 6, 7 or 9 OFDMA symbols, but this is only an example and the number of OFDMA symbols included in the subframe is not limited. The number of OFDMA symbols included in the subframe may be variously changed according to the channel bandwidth and the length of the CP. A type of a subframe may be defined according to the number of OFDMA symbols included in the subframe. For example, the type-1 subframe may be defined to include 6 OFDMA symbols, the type-2 subframe includes 7 OFDMA symbols, the type-3 subframe includes 5 OFDMA symbols, and the type-4 subframe includes 9 OFDMA symbols. have. One frame may include subframes of the same type. Alternatively, one frame may include different types of subframes. That is, the number of OFDMA symbols included in each subframe in one frame may be the same or different. Alternatively, the number of OFDMA symbols of at least one subframe in one frame may be different from the number of OFDMA symbols of the remaining subframes in the frame.

A time division duplex (TDD) scheme or a frequency division duplex (FDD) scheme may be applied to the frame. In the TDD scheme, each subframe is used for uplink transmission or downlink transmission at different times at the same frequency. That is, subframes in a frame of the TDD scheme are classified into an uplink subframe and a downlink subframe in the time domain. The switching point refers to a point where the transmission direction is changed from the uplink region to the downlink region or from the downlink region to the uplink region. In the TDD scheme, the switching point may have two switching points in each frame. In the FDD scheme, each subframe is used for uplink transmission or downlink transmission at different frequencies at the same time. That is, subframes in the frame of the FDD scheme are divided into an uplink subframe and a downlink subframe in the frequency domain. Uplink transmission and downlink transmission occupy different frequency bands and may be simultaneously performed.

The SFH may carry essential system parameters and system configuration information. The SFH may be located in the first subframe in the superframe. SFH may occupy the last five OFDMA symbols of the first subframe. The superframe header may be classified into primary SFH (P-SFH) and secondary SFH (S-SFH; secondary-SFH). P-SFH and S-SFH may be transmitted every superframe. S-SFH may be transmitted in two consecutive superframes. Information transmitted to the S-SFH can be divided into three subpackets (S-SFH SP1, S-SFH SP2, S-SFH SP3). Each subpacket may be transmitted periodically with a different period. The importance of information transmitted through S-SFH SP1, S-SFH SP2, and S-SFH SP3 may be different from each other. S-SFH SP1 may be transmitted in the shortest period, and S-SFH SP3 may be transmitted in the longest period. S-SFH SP1 contains information about network re-entry. S-SFH SP2 includes information about initial network entry and network discovery. S-SFH SP3 contains the remaining important system information.

3 shows an example of an uplink resource structure.

Each uplink subframe may be divided into at least one frequency partition. In FIG. 3, a subframe is divided into two frequency partitions FP1 and FP2 as an example, but the number of frequency partitions in the subframe is not limited thereto. The number of frequency partitions may be up to four. Each frequency partition consists of at least one Physical Resource Unit (PRU) over the entire OFDMA available within a subframe. Each frequency partition may also include contiguous / localized and / or distributed PRUs. Each frequency partition may be used for other purposes, such as fractional frequency reuse (FFR). In FIG. 3, the second frequency partition FP2 includes both continuous resource allocation and distributed resource allocation. 'Sc' means a subcarrier.

The PRU is a basic physical unit for resource allocation and includes Psc consecutive subcarriers and Nsym consecutive OFDMA symbols. Psc may be 18. Nsym may be equal to the number of OFDMA symbols included in one subframe. Therefore, Nsym may be determined according to the type of the subframe. For example, when one subframe consists of 6 OFDMA symbols, the PRU may be defined with 18 subcarriers and 6 OFDMA symbols.

 A Logical Resource Unit (LRU) is a basic logical unit for distributed and continuous resource allocation, and includes Psc subcarriers and Nsym OFDMA symbols. The size of the LRU for transmission of the control channel is equal to the size of the LRU for data transmission. Multiple users may share one control LRU. The LRU may also include a pilot. Thus, the appropriate number of subcarriers in one LRU depends on the number of assigned pilots and the presence of control channels.

Distributed Logical Resource Units (DLRUs) may be used to obtain frequency diversity gains. The DLRU includes subcarrier groups distributed in one frequency partition. The size of the DLRU is equal to the size of the PRU. The minimum unit forming the DLRU is a tile, and the size of an uplink tile is 6 subcarriers * Nsym OFDMA symbols. N _sym may vary depending on the subframe type.

Contiguous Logical Resource Units (CLRUs) may be used to obtain frequency selective scheduling gains. The CLRU includes a group of contiguous subcarriers. The size of the CLRU is equal to the size of the PRU.

Meanwhile, in a cellular system in which multi-cells exist, a fractional frequency reuse (FFR) technique may be used. The FFR technique divides an entire frequency band into a plurality of frequency partitions (FPs) and allocates a frequency partition to each cell. Different frequency partitions may be allocated between adjacent cells through the FFR scheme, and the same frequency partition may be allocated between distant cells. Accordingly, inter-cell interference (ICI) may be reduced, and performance of a cell edge terminal may be improved.

4 shows an example of a method of dividing an entire frequency band into a plurality of frequency partitions.

Referring to FIG. 4, the entire frequency band is divided into a first frequency partition FP0, a second frequency partition FP1, a third frequency partition FP2, and a fourth frequency partition FP3. Each frequency partition may be divided logically and / or physically from the entire frequency band.

5 shows an example of a cellular system in which the FFR technique is used.

Referring to FIG. 5, each cell is divided into an inner cell and a cell edge. In addition, each cell is divided into three sectors. The entire frequency band is divided into four frequency partitions FP0, FP1, FP2, and FP3.

The first frequency partition FP0 is allocated inside the cell. Each sector of the cell edge is allocated any one of the second frequency partition FP1 to the fourth frequency partition FP3. In this case, different frequency partitions are allocated between adjacent cells. Hereinafter, the assigned frequency partition is referred to as an active frequency partition, and the unassigned frequency partition is referred to as an inactive frequency partition. For example, when the second frequency partition FP1 is allocated, the second frequency partition is an active frequency partition, and the third frequency partition FP2 and the fourth frequency partition FP3 become inactive frequency partitions.

The frequency reuse factor (FRF) may be defined as how many cells (or sectors) the entire frequency band can be divided into. In this case, the frequency reuse coefficient inside the cell may be 1, and the frequency reuse coefficient of each sector at the cell edge may be 3.

When a plurality of cells exists, uplink resources may be mapped through a process such as subband partitioning, miniband permutation, frequency partitioning, and the like.

6 shows an example of a subband partitioning process. 10 illustrates a subband partitioning process when the bandwidth is 10 MHz.

A plurality of PRUs are allocated to subbands (SBs) and minibands (MBs). The subband contains N1 contiguous PRUs, and the miniband contains N2 contiguous PRUs. N1 = 4 and N2 = 1. Subbands are suitable for frequency selective resource allocation because contiguous PRUs are allocated in the frequency domain. Minibands are suitable for frequency-distributed resource allocation and can be permuted in the frequency domain.

이며, PRU의 총 개수 N_PRU=L_SB+L_MB이다. The number of subbands may be represented by K _SB . The number of PRUs allocated to a subband may be represented by L _SB , and L _SB = N1 * K _SB . K _SB can vary with bandwidth. K _SB may be determined by an uplink subband allocation count (USAC). The length of the USAC may be 3 to 5 bits, and may be broadcast through SFH. The remaining PRUs allocated to the subbands are allocated to the minibands. The number of minibands can be represented by K _MB . The number of PRUs allocated to the miniband may be represented by L _MB , where L _MB = N2 * K _MB . Maximum number of subbands that can be formed in a resource zone

The total number of PRUs is N _PRU = L _SB + L _MB .

The plurality of PRUs are divided into subbands and minibands and rearranged in subband PRUs (PRU _SBs ) and miniband PRUs (PRU _MBs ). The PRUs in the PRU _SB are each indexed to any of 0-(L _SB -1), and the PRUs in the PRU _MB are each indexed to either 0-(L _MB -1). In addition, the PRU _MB is mapped to a permutation PRU (PPRU _MB ) in the miniband permutation process. In the frequency partitioning process, PRUs of the PRU _SB and the PPRU _MB are allocated to at least one frequency partition.

7 is an exemplary diagram illustrating a frequency band.

The entire frequency band is divided into a plurality of subbands. In 'SBn' representing a subband, n represents an index of each subband. In FIG. 7, the total bandwidth is divided into 12 subbands. However, this is not a limitation and the entire band may be divided into 12 or less subbands.

Meanwhile, the Best-M scheme means selecting M specific subbands from among a plurality of subbands. For example, M subbands having the best channel state can be selected. The best band means the selected M subbands. The remaining band is the remaining subbands except the best band among the entire bands. For example, in FIG. 7, subbands 3, 6, and 11 are selected as best bands in a Best-3 manner.

Hereinafter, a control channel for transmitting a control signal or a feedback signal will be described. The control channel may be used for transmitting various kinds of control signals for communication between the base station and the terminal. Hereinafter, the control channel described may be applied to an uplink control channel and a downlink control channel.

The control channel may be designed in consideration of the following points.

(1) The plurality of tiles included in the control channel may be distributed to the time domain or the frequency domain to obtain frequency diversity gain. For example, given that the DLRU includes three tiles consisting of six consecutive subcarriers on six OFDM symbols, the control channel may include three tiles and each tile may be distributed in the frequency domain or the time domain. have. Alternatively, the control channel may include at least one tile, and the tile may include a plurality of mini tiles so that the plurality of mini tiles may be distributed in a frequency domain or a time domain. For example, the minitile may be composed of (OFDM symbol × subcarrier) = 6 × 6, 3 × 6, 2 × 6, 1 × 6, 6 × 3, 6 × 2, 6 × 1, and the like. Assuming that a control channel including a tile of a PUSC structure of (OFDM symbol × subcarrier) = 3x4 of IEEE 802.16e and a control channel including a mini tile are multiplexed by frequency division multiplexing (FDM), (OFDM symbol × subcarrier) = 6 × 2, 6 × 1 and the like. Considering only the control channel including the mini-tiles, the mini-tiles may consist of (OFDM symbols × subcarriers) = 6 × 2, 3 × 6, 2 × 6, 1 × 6, and the like.

(2) In order to support a high speed terminal, the number of OFDM symbols constituting the control channel should be configured to the minimum. For example, in order to support a terminal moving at 350 km / h, the number of OFDM symbols constituting the control channel is appropriately three or less.

(3) The transmission power per symbol of the terminal is limited, and in order to increase the transmission power per symbol of the terminal, the larger the number of OFDM symbols constituting the control channel is, the more advantageous. Therefore, the number of appropriate OFDM symbols should be determined in consideration of the transmission power per symbol of the fast terminal of (2) and the terminal of (3).

(4) For coherent detection, pilot subcarriers for channel estimation should be distributed evenly in the time domain or frequency domain. Coherent detection is a method of obtaining data on a data subcarrier after performing channel estimation using a pilot. For power boosting of the pilot subcarriers, the number of pilots per OFDM symbol of the control channel must be the same to maintain the same transmit power per symbol.

(5) For non-coherent detection, the control signal should be composed or spread of orthogonal code / sequence or semi-orthogonal code / sequence.

The uplink control channel includes a fast feedback channel (FFBCH), a HARQ feedback channel (HFBCH), a hybrid automatic repeat request feedback channel (HFBCH), a ranging channel, a bandwidth request channel (BRCH), and the like. It may include. Information such as CQI, MIMO feedback, ACK / NACK, uplink synchronization signal, bandwidth request, etc. may be transmitted by the uplink control channel. The FFBCH, HFBCH, ranging channel, BRCH, etc. may be located anywhere in an uplink subframe or frame.

The uplink control channel may be allocated through downlink control information transmitted through the downlink from the base station. The downlink control information may be broadcast to all terminals or transmitted to a unicast service for each terminal. The above-described P-SFH or S-SFH is a broadcast downlink control signal, and a plurality of A-MAP IEs (Advanced-MAP Information Elements) may be defined as basic elements of unicast service control.

A feedback allocation A-MAP IE for dynamically allocating or releasing a feedback channel among the plurality of A-MAP IEs may be transmitted to the terminal. Feedback Allocation Feedback channels that can be allocated or released by the A-MAP IE include PFBCH and SFBCH. When a feedback channel already allocated to a downlink carrier exists and a new feedback channel is allocated to the corresponding downlink carrier, the original feedback channel may be automatically released.

Table 1 is an example of a feedback allocation A-MAP IE for allocation of a feedback channel.

Syntax Size in bits Description / Notes Feedback-Allocation-MAP_IE () { - - A-MAP IE Type [4] Feedback Allocation A-MAP IE = 0b0010 Channel Index Variable Feedback channel index within the UL fast feedback control resource region Short-term Feedback Period (p) [3] A feedback is transmitted on the FBCH every 2 ^p frames Long-term Feedback Period (q) [2] A long-term feedback is transmitted on the FBCH every 2 ^q short-term feedback opportunity
If q = 0b00, long-term feedback is not used. Frame offset [3] The AMS starts reporting at the frame of which the number has the same 3 LSB as the specified frame offset. If the current frame is specified, the AMS should start reporting in eight frames Allocation Duration (d) [3] A FBCH is transmitted on the FBCH channels indexed by Channel Index for 8 * 2 ^d frames. If d = 0b000, the FBCH is deallocated. If d = 0b111, the AMS should report until the ABS command for the AMS to stop. ACK Allocation Flag [One] Indicate if one ACK channel is allocated If (ACK Allocation Flag == 0b1) { HFA [3] HARQ feedback channel allocation for Feedback Channel De-allocation confirmation } MaxMt Variable
[1-2]
Variable number of bits-depends on number of transmit antenna Nt
If Nt = 2 (SU-MIMO and MU-MIMO):
0b0: 1, 0b1: 2
If Nt = 4 (SU-MIMO and MU-MIMO):
0b00: 1, 0b01: 2, 0b10: 3, 0b11: 4
If Nt = 8 (SU-MIMO):
0b000: 1, 0b001: 2, 0b011: 4, 0b111: 8
If Nt = 8: (MU-MIMO):
0b00: 1, 0b01: 2, 0b10: 3, 0b11: 4 MFM [3] MIMO Feedback Mode as defined in Table 691 If (MFM = 2, 3, 5, 6) { Feedback Format [2] } If (MFM = 0,1,4,7) {    FPI [2] Frequency partition indication: ABS indicate AMS to send wideband CQI and STC rate of the frequency partition and reuse factor in the future:
0b00: Frequency partition index 0
0b01: Frequency partition index 1
0b10: Frequency partition index 2
0b11: Frequency partition index 3 } If (MFM = 0,1 & Long-term Feedback Period! = 0b00) { Long term FPI [2] Frequency partition indication: ABS indicate AMS to send wideband CQI and STC rate for the second frequency partition using long term feedback:
0b00: Frequency partition index 0
0b01: Frequency partition index 1
0b10: Frequency partition index 2
0b11: Frequency partition index 3 } If (MFM == 3,4,6,7) { CL SU and MU MIMO CM [2] Codebook Feedback Mode and Codebook Coordination Enable
0b00: standard with CCE disabled
0b01: adaptive with CCE disabled
0b10: differential with CCE disabled
0b11: standard with CCE enabled CS [One] Codebook subset } If (MFM = 0, 1, 5) { Measurement Method Indication [One] 0b0: Use the midamble for CQI measurements
0b1: Use pilots in OL region with MaxMt streams for CQI measurements } Padding Variable Padding to reach byte boundary MCRC [16] 16 bit CRC masked by Station ID } - -

Feedback definition of Table 1 Definition of each field constituting A-MAP IE is as follows.

Channel index: Defines an index on an uplink resource of a feedback channel through which a terminal transmits feedback information. At this time, a one-to-one correspondence between the corresponding terminal and the channel index is formed. That is, the feedback channels allocated to each terminal do not overlap each other.

Short-term feedback period: Defines a period in which the short-term feedback information that changes relatively frequently according to the channel environment is transmitted among the feedback information. The short-term feedback information may include a CQI, a precoding matrix indicator (PMI), and the like. Short-term feedback information is transmitted every 2 ^p frames by the short-term feedback period.

Long-term feedback period: Defines a period during which long-term feedback information that does not change frequently among feedback information is transmitted. The long term feedback information may include a subband index, a MIMO feedback mode, and the like. Long-term feedback information is transmitted every 2 ^q frames by the long-term feedback period. When q = 0, the long-term feedback information is not transmitted.

Allocation duration: Defines an allocation period of a feedback channel, and the feedback channel is allocated by 8 * 2 ^d frames when the value of the field indicating the allocation period is ^d . When d = 0b000, the feedback channel is released, and when d = 0b111, the feedback channel persists until a release command is received from the base station.

ACK allocation flag: This is a field for allocation of an ACK channel through which a message confirming release of a feedback channel is transmitted. When d = 0b000 indicating the allocation period, the value of the ACK allocation flag becomes 0b1. Even when d = 0b000, when the channel index of the newly allocated feedback channel is the same as the channel index of the released feedback channel, the ACK allocation flag. The value of is set to 0b1.

-MFM: Defines a MIMO feedback mode, which can be defined by Table 2 to be described later.

Feedback format: When transmitting feedback information through a feedback channel, a feedback format index may be defined, and the type of feedback information transmitted may be indicated. Feedback formats according to different MIMO feedback modes may be defined by Tables 3 to 7 described below.

Frequency Partition Indication (FPI): Indicates information of a frequency partition measuring feedback information to be transmitted in a short feedback period. When the number of frequency partitions is one, the FPI field may not exist.

Long term FPI: indicates information of another frequency partition measuring feedback information to be transmitted in a long feedback period. The long-term FPI field does not exist when the number of frequency partitions is one, and is implicitly signaled by the FPI field when the number of frequency partitions is two. Indicates the maximum number of users that have been created.

CM (Codebook Mode): indicates a codebook feedback mode.

Measurement method indication: indicates a midamble or pilot for CQI measurement.

The MIMO feedback mode may support each MNIMO transmission. When the base station allocates a feedback channel, it informs the terminal of the MIMO feedback mode, and the terminal transmits feedback information accordingly. Table 2 shows an example of the MIMO feedback mode and thus the supported MIMO transmission modes.

Feedback Mode Description Feedback contents Type of RU Supported MIMO transmission mode Mode 0 OL SU MIMO SFBC / SM (Diversity) 1. STC Rate
2. Wideband CQI
Diversity (DRU, Mini-band based CRU) MIMO mode 0 and MIMO mode 1.
Flexible adaptation between the two modes
STC Rate = 1: SFBC CQI
STC Rate 2: SM CQI
In DRU: Mt = 2 for SM.In Miniband based CRU: Mt> = 2 for SM Mode 1 OL SUMIMO SM (Diversity)
1. STC Rate
2. Wideband CQI Diversity (Mini-band based CRU) MIMO mode 1 Mode 2 OL SUMIMO SM (localized) 1. STC Rate
2. Subband CQI
3. Subband Selection Localized (Subband based CRU, Mini-band based CRU) MIMO mode 1 Mode 3 CL SU MIMO (localized) 1. STC Rate
2. Subband CQI
3. Subband PMI
4.Subband selection
[5. Wideband PMI]
6. Wideband correlation Matrix Localized (Subband based CRU, Mini-band based CRU) MIMO mode 2 Mode 4 CL SU MIMO (Diversity) 1. Wideband CQI
[2. Wideband PMI]
3. Wideband correlation matrix Diversity (Mini-band based CRU) MIMO mode 2 (Mt = 1) Mode 5 OL MU MIMO (localized)
1.Subband CQI
2. Subband Selection
3.Stream indicator Localized (Subband based CRU, Mini-band based CRU) MIMO mode 3
Mode 6 CL MU MIMO (localized) 1.Subband CQI
2. Subband PMI
3. Subband Selection
[4. Wideband PMI]
5. Wideband correlation matrix Localized (Subband based CRU, Mini-band based CRU) MIMO mode 4
Mode 7 CL MU MIMO (Diversity) 1. Wideband CQI
[2. Wideband PMI]
3. Wideband correlation matrix Diversity (Mini-band based CRU) MIMO mode 4

Referring to Table 2, the supported MIMO transmission modes are different for each MIMO feedback mode. For example, MIMO feedback mode 0 is an Open Loop-Single User (OL-SU) MIMO Environment Space-Frequency Block Code (SFBC) within diversity permutation. ) And the application of spatial multiplexing (SM). The UE measures wideband CQI for SFBC and SM, and reports the CQI and STC (Space Time Coding) rate to the base station. MIMO feedback mode 3 supports a closed loop-single user (CL-SU) MIMO environment within localized permutation for frequency selective scheduling. MIMO feedback mode 5 supports an Open Loop-Multi User (OL-MU) MIMO environment within localized permutation for frequency selective scheduling. MIMO feedback mode 7 supports a closed loop-multi user (CL-MU) MIMO environment within diversity permutation using wideband beamforming.

The FFBCH carries feedback of CQI and / or MIMO information, and may be divided into two types, a primary fast feedback channel (PFBCH) and a secondary fast feedback channel (SFBCH). The PFBCH carries 4 to 6 bits of information and provides wideband CQI and / or MIMO feedback. The SFBCH carries from 24 bits of information and provides narrowband CQI and / or MIMO feedback. SFBCH can support more control information bits using a higher code rate. PFBCH supports non-coherent detection using no pilot, and SFBCH supports coherent detection using pilot. The fast feedback channel starts at a predetermined position, and the size of the fast feedback channel may be defined by a downlink control signal. The fast feedback channel may be allocated periodically. The number of fast feedback channels allocated to the terminal, which is the base station, may be one or less.

The feedback format defines the type of feedback information transmitted by the fast feedback channel. The feedback format may be defined differently according to the MIMO feedback mode. That is, feedback information may be configured differently according to the MIMO feedback mode, and a period in which the corresponding feedback information is transmitted may also be set.

Table 3 is an example of a feedback format when the MIMO feedback mode is any one of 0, 1, 4, and 7.

MFM FBCH # reports Feedback Fields Size in bits Description / Notes 0 PFBCH 2 Short Wideband CQI and STC rate N / A Joint encoding of CQI and STC rate
Encoding type 0 Long Wideband CQI and STC rate N / A Joint encoding of CQI and STC rate
Encoding type 0
Long term FPI for FFR One PFBCH 2 Short Wideband CQI and STC rate N / A Joint encoding of CQI and STC rate
Encoding type 0 Long Wideband CQI and STC rate N / A Joint encoding of CQI and STC rate
Encoding type 0
Long term FPI for FFR 4 PFBCH 2 Short Wideband CQI N / A STC rate = 1
Encoding type 0 Long Wideband PMI N / A PMI for rank 1
Encoding type 2 7 PFBCH 2 Short Wideband CQI N / A STC rate = 1
Encoding type 0 Long Wideband PMI N / A PMI for rank 1
Encoding type 2

When the MIMO feedback mode is any one of 0, 1, 4, or 7, feedback information of the entire broadband is transmitted. At this time, PFBCH is used as a feedback channel for carrying feedback information. The wideband CQI and STC rate may be transmitted every frame without the long term feedback information, or the wideband PMI may be transmitted as the long term feedback information.

Table 4 is an example of a feedback format when the MIMO feedback mode is 2.

Feedback Format FBCH # reports Feedback Fields Size in bits Description / Notes 0 (M = 1) PFBCH 2 Short Subband CQI and STC rate (rate = 1 and 2) N / A Joint encoding of CQI and STC rate with PFBCH
PFBCH encoding Type 0 Long Subband index N / A PFBCH encoding Type 1 1 (M = 1) SFBCH One Subband index
Subband CQI
STC ratePFBCH indicator 3, 4, or 5
4
1-31 Subband index for 5, 10, or 20 MHz
Support of STC rate 1 to 8 2 (M = 3) SFBCH 2 Short Subband avg CQI differential CQI 42 (3 = 6 Subband index for 5, 10, or 20 MHz Long Subband index Wideband STC ratePFBCH indicator 5, 8 or 111-31 3 (M = 5) SFBCH 2 Short Subband avg CQI differential CQI 42 (5 = 10 Long Subband index Wideband STC ratePFBCH indicator 3, 10, or 161-31

MIMO feedback mode 2 supports open loop MIMO, where narrowband feedback information is transmitted. That is, feedback information may be measured in one, three or five subbands (M in Table 4) selected and transmitted on the PFBCH or SFBCH. The feedback information is transmitted through the PFBCH when M = 1, and through the SFBCH when M = 3 or 5. The CQI in the subband selected as the short term feedback information is transmitted, and the subband index is transmitted as the long term feedback information.

Table 5 is an example of a feedback format when the MIMO feedback mode is three.

Feedback Format FBCH # reports Feedback Fields Size in bits Description / Notes 0 (M = 1) PFBCH 3 Short Subband CQI N / A PFBCH encoding Type 0 Short Subband PMI N / A PFBCH encoding Type 2 Long Subband index N / A PFBCH encoding Type 1 One
(M = 2) SFBCH 2 Short Subband differential CQISubband PMI 2 (2 (3 ~ 6) (2 Subband index for 5, 10, or 20 MHz Long Subband index Wideband STC rate Subband avg CQIPFBCH indicator 4, 7 or 91 ~ 34
One 2
(M = 3) SFBCH 2 Short Subband differential CQIsubband PMI 2 (3 (3 ~ 6) (3 Long Subband index
Wideband STC rate Subband avg CQIPFBCH indicator 5, 8 or 111-341 3
(M = 4) SFBCH 2 Short Subband differential CQISubband PMI 2 (4 (3-4) (4 Long Subband index
Wideband STC rate Subband avg CQIPFBCH indicator 4, 9 or 141 ~ 341

MIMO feedback mode 3 supports closed-loop MIMO, and narrowband feedback information is transmitted as in MIMO feedback mode 2. In this case, the PMI in the selected subband may be transmitted together with the CQI in the selected subband.

Table 6 shows an example of a feedback format when the MIMO feedback mode is five.

Feedback Format FBCH # Reports Feedback Fields Size in bits Description / Notes 0 (M = 1) SFBCH One Short Subband indexSubband CQI
Stream Index
PFBCH indicator 3, 4, or 5
4
1 ~ 2
One Subband index for 5, 10, or 20 MHz 1 (M = 2) SFBCH 2 Short Subband avg_CQISubband differential CQIStream Index 42 (2 = 4 (1 ~ 2) (2 Long Subband index
PFBCH indicator 4, 7, or 9
One Subband index for 5, 10, or 20 MHz 2 (M = 3) SFBCH 2 Short Subband avg_CQISubband differential CQIStream Index 42 (3 = 63 ((1 ~ 2) Long Subband index
PFBCH indicator 5, 8, or 11
One Subband index for 5, 10, or 20 MHz 3 (M = 5) SFBCH 3 Short Subband avg_CQISubband differential CQIStream Index 42 (5 = 10 (1 ~ 2) (5 Long Subband index
PFBCH indicator 3, 10, or 16
One Subband index for 5, 10, or 20 MHz

Table 7 shows an example of a feedback format when the MIMO feedback mode is 6.

Feedback Format FBCH # reports Feedback Fields Size in bits Description / Notes 0 (M = 1) PFBCH 3 Short Subband CQI N / A PFBCH encoding Type 0 Short Subband PMI N / A PFBCH encoding Type 2 Long Subband index N / A PFBCH encoding Type 1 1 (M = 2) SFBCH 2 Short Subband avg_CQISubband differential CQIStream Index 42 (2 = 4 (1 ~ 2) (2 Long Subband index
PFBCH indicator 4, 7, or 9
One Subband index for 5, 10, or 20 MHz 2 (M = 3) SFBCH 2 Short Subband avg_CQISubband differential CQIStream Index 42 (3 = 63 ((1 ~ 2) Long Subband index
PFBCH indicator 5, 8, or 11
One Subband index for 5, 10, or 20 MHz 3 (M = 5) SFBCH 3 Short Subband avg_CQISubband differential CQIStream Index 42 (5 = 10 (1 ~ 2) (5 Long Subband index
PFBCH indicator 3, 10, or 16
One Subband index for 5, 10, or 20 MHz

8 shows an example of an uplink resource used for PFBCH. The PFBCH may include three distributed uplink feedback mini tiles (FMTs). The FMT may be defined as two consecutive subcarriers and six OFDM symbols. One resource unit including 18 subcarriers and 6 OFDM symbols may include 3 FFBCHs.

9 is a block diagram illustrating a process of mapping feedback information to a PFBCH. In step S50, the PFBCH sequence is generated using the PFBCH payload. The PFBCH sequence may be selected from a predetermined set of PFBCH sequences. Table 8 is an example of a PFBCH sequence set.

Index Sequence Index Sequence 0 111111111111 32 101011001001 One 101111010110 33 111011100000 2 011010111101 34 001110001011 3 001010010100 35 011110100010 4 101010101010 36 100111111010 5 111010000011 37 110111010011 6 001111101000 38 000010111000 7 011111000001 39 010010010001 8 110011001100 40 111110011100 9 100011100101 41 101110110101 10 010110001110 42 011011011110 11 000110100111 43 001011110111 12 100110011001 44 101010011111 13 110110110000 45 111010110110 14 000011011011 46 001111011101 15 010011110010 47 011111110100 16 101011111100 48 111111001010 17 111011010101 49 101111100011 18 001110111110 50 011010001000 19 011110010111 51 001010100001 20 111110101001 52 110010101111 21 101110000000 53 100010000110 22 011011101011 54 010111101101 23 001011000010 55 000111000100 24 100111001111 56 100110101100 25 110111100110 57 110110000101 26 000010001101 58 000011101110 27 010010100100 59 010011000111 28 110010011010 60 110011111001 29 100010110011 61 100011010000 30 010111011000 62 010110111011 31 000111110001 63 000110010010

In step S51, the generated PFBCH sequence is modulated and repeated, and is mapped to the uplink PFBCH symbol s [k]. In this case, 0 of the PFBCH sequence may be mapped to 1 and 1 may be mapped to -1. In step S52, the uplink PFBCH symbol s [k] is mapped to a subcarrier of FMT.

Four encoding types may be defined in the transmission of the PFBCH. Feedback Allocation An encoding type corresponding to the MIMO feedback mode and feedback format defined in the A-MAP IE may be used. An index value of 6 bits corresponding to the padback information defined in each encoding type may be transmitted through the PFBCH.

Table 9 is an example of PFBCH encoding type 0.

Index Content (Value) Description / Notes 0 STC rate = 1, MCS = 0000 One STC rate = 1, MCS = 0001 2 STC rate = 1, MCS = 0010 3 STC rate = 1, MCS = 0011 4 STC rate = 1, MCS = 0100 5 STC rate = 1, MCS = 0101 6 STC rate = 1, MCS = 0110 7 STC rate = 1, MCS = 0111 8 STC rate = 1, MCS = 1000 9 STC rate = 1, MCS = 1001 10 STC rate = 1, MCS = 1010 11 STC rate = 1, MCS = 1011 12 STC rate = 1, MCS = 1100 13 STC rate = 1, MCS = 1101 14 STC rate = 1, MCS = 1110 15 STC rate = 1, MCS = 1111 16 STC rate = 2, MCS = 0000 17 STC rate = 2, MCS = 0001 18 STC rate = 2, MCS = 0010 19 STC rate = 2, MCS = 0011 20 STC rate = 2, MCS = 0100 21 STC rate = 2, MCS = 0101 22 STC rate = 2, MCS = 0110 23 STC rate = 2, MCS = 0111 24 STC rate = 2, MCS = 1000 25 STC rate = 2, MCS = 1001 26 STC rate = 2, MCS = 1010 27 STC rate = 2, MCS = 1011 28 STC rate = 2, MCS = 1100 29 STC rate = 2, MCS = 1101 30 STC rate = 2, MCS = 1110 31 STC rate = 2, MCS = 1111 32 STC rate = 3, MCS = 0100 33 STC rate = 3, MCS = 0101 34 STC rate = 3, MCS = 0110 35 STC rate = 3, MCS = 0111 36 STC rate = 3, MCS = 1000 37 STC rate = 3, MCS = 1001 38 STC rate = 3, MCS = 1010 39 STC rate = 3, MCS = 1011 40 STC rate = 3, MCS = 1100 41 STC rate = 3, MCS = 1101 42 STC rate = 3, MCS = 1110 43 STC rate = 3, MCS = 1111 44 STC rate = 4, MCS = 1000 45 STC rate = 4, MCS = 1001 46 STC rate = 4, MCS = 1010 47 STC rate = 4, MCS = 1011 48 STC rate = 4, MCS = 1100 49 STC rate = 4, MCS = 1101 50 STC rate = 4, MCS = 1110 51 STC rate = 4, MCS = 1111 52 Reserved 53 Reserved 54 Reserved 55 Event-driven Indicator (EDI) for Buffer management (80% full) Event-driven for buffer management 56 Event-driven Indicator (EDI) for Buffer management (full) 57 Event-driven Indicator (EDI) for request for switching MFM Indicate request to switch MIMO feedback Mode between distributed and localized allocations 58 Event driven indicator (EDI) for frequency partition 0 indication (reuse-1) AMS informs ABS about the frequency partition index (for MIMO feedback modes 0,1,4,7) 59 Event driven indicator (EDI) for frequency partition 1 indication (reuse-3) 60 Event driven indicator (EDI) for frequency partition 2 indication (reuse-3) 61 Event driven indicator (EDI) for frequency partition 3 indication (reuse-3) 62 Event-driven Indicator (EDI) for Bandwidth Request Indicator (sequence 1) Event-driven Indicator for Bandwidth request
63 Event-driven Indicator (EDI) for Bandwidth Request Indicator (sequence 2)

According to Table 9, PFBCH encoding type 0 indicates the STC rate and Modulation and Coding Scheme (MCS) level of the measured channel.

Table 10 is an example of PFBCH encoding type 1.

Index Content (Value) Description / Notes 0 Subband index 0 Subband index for Best-1 subband One Subband index 1 2 Subband index 2 3 Subband index 3 4 Subband index 4 5 Subband index 5 6 Subband index 6 7 Subband index 7 8 Subband index 8 9 Subband index 9 10 Subband index 10 11 Subband index 11 12 Reserved Reserved … … 54 Reserved 55 Event-driven Indicator (EDI) for Buffer management (80% full) Event-driven for buffer management 56 Event-driven Indicator (EDI) for Buffer management (full) 57 Event-driven Indicator (EDI) for request for switching MFM Indicate request to switch MIMO feedback Mode between distributed and localized allocations 58 Event driven indicator (EDI) for frequency partition 0 indication (reuse-1) AMS informs ABS about the frequency partition index (for MIMO feedback modes 0,1,4,7) 59 Event driven indicator (EDI) for frequency partition 1 indication (reuse-3) 60 Event driven indicator (EDI) for frequency partition 2 indication (reuse-3) 61 Event driven indicator (EDI) for frequency partition 3 indication (reuse-3) 62 Event-driven Indicator (EDI) for Bandwidth Request Indicator (sequence 1) Event-driven Indicator for Bandwidth request
63 Event-driven Indicator (EDI) for Bandwidth Request Indicator (sequence 2)

By Table 10, PFBCH encoding type 1 indicates the index of the Best-1 subband to measure the narrowband CQI.

PFBCH encoding type 2 is used for PMI reporting.

10 is a block diagram illustrating a process in which feedback information is mapped to SFBCH. In step S60, the SFBCH payload is channel coded via a convolutional code. In this case, the coding process may vary according to the length of the payload. In step S61, quadrature phase shift keying (QPSK) modulation is performed on the channel coded symbol. In step S62, the modulation symbol and the pilot sequence are combined to form one symbol sequence. The symbol sequence is mapped to a subcarrier of the FMT.

On the other hand, when feeding back the measurement result for the selected subband (Best-M) rather than the entire band, the index of the selected subband is fed back together. At least one subband is selected from a predetermined set of subbands, and a measurement result and a subband index of the corresponding subband are fed back. When constructing the subband set or feeding back the subband index, the following matters need to be considered.

1) The number of subbands included in the bandwidth varies according to the bandwidth. Six 5MHz bandwidths, 12 10MHz bandwidths, and 24 subbands each have a 20MHz bandwidth. Therefore, if the same number of subband indexes are fed back regardless of the bandwidth, the size of the subband set varies depending on the bandwidth. On the contrary, if the size of the subband set is fixed, the number of subband indexes fed back varies.

2) Since the subband includes four consecutive CLRUs, feedback information for the subband consisting of CLRUs needs to be fed back.

3) When bandwidth is divided into a plurality of frequency partitions, transmission power applied to each frequency partition may be different. Therefore, frequency partitions should be considered when selecting subbands or determining subband sets.

Accordingly, the present invention proposes a method for constructing a subband set or feeding back a subband index in view of the above.

11 is an embodiment of a proposed feedback transmission method.

In step S100, the terminal selects at least one subband from among a plurality of subbands constituting the subband set. In step S120, the terminal transmits the feedback information measured for the at least one subband to the base station. In this case, the feedback information includes the at least one subband index. In addition, the at least one subband may be selected in consideration of a frequency partition or resource mapping of the plurality of subbands.

In configuring a subband set, one subband may configure one subband set. Thus, the 5 MHz bandwidth includes 6 subbands, the 10 MHz bandwidth 12, and the 20 MHz bandwidth 24 subband sets, respectively. When the subband index is fed back through PFBCH, PFBCH encoding type 1 is used. Since the current PFBCH encoding type 1 is configured to select one of 12 subbands, a set of 24 subbands included in the 20 MHz bandwidth To support the PFBCH encoding type 1 may be newly configured as shown in Table 11.

Index Content (Value) 0 Subband index 0 One Subband index 1 2 Subband index 2 3 Subband index 3 4 Subband index 4 5 Subband index 5 6 Subband index 6 7 Subband index 7 8 Subband index 8 9 Subband index 9 10 Subband index 10 11 Subband index 11 12 Subband index 12 13 Subband index 13 14 Subband index 14 15 Subband index 15 16 Subband index 16 17 Subband index 17 18 Subband index 18 19 Subband index 19 20 Subband index 20 21 Subband index 21 22 Subband index 22 23 Subband index 23 24 ...

For the 5 MHz bandwidth, sequences from 0 to 5 can be used in Table 11. Similarly, a sequence of 0 to 11 can be used in a 10 MHz bandwidth, and a sequence of 0 to 23 can be used in a 20 MHz bandwidth. The UE selects one subband from among 6, 12 or 24 sequences corresponding to the bandwidth of the system, measures feedback information in the corresponding subband, and feeds it back with the corresponding subband index.

개의 비트를 이용할 수 있다. 예를 들어 S=24, M=3일 때 선택 가능한 서브밴드의 조합은

이다. 2024개의 서브밴드 조합은 11비트로 표현할 수 있고, 이를 이용하여 선택된 서브밴드 인덱스를 피드백 할 수 있다. 다만, 이때 대역폭 및 선택된 서브밴드의 개수에 따라서 필요한 비트의 수가 달라진다.If the number of subbands selected for measuring the feedback information is one or more, the subband index and the measured feedback information may be fed back through the SFBCH. In this case, the subband index may be fed back using a bitmap method. This requires as many bits as the number of subbands. That is, a bit corresponding to the selected subband among the number of bits of the subband set may be allocated to '', and a bit corresponding to the unselected subband may be allocated as ''. For example, assuming that 1, 3, and 7 subbands are selected in the 10 MHz bandwidth, a bit sequence of 12 '' in length is fed back through the SFBCH. Alternatively, in order to reduce signaling overhead, a sequence indicating a combination of selectable subbands in a subband set may be used in order. That is, when the number of subband sets is S and the number of selected subbands is M, as many as _{S M M} combinations are possible and all possible subband combinations can be represented.

Bits are available. For example, when S = 24 and M = 3, the combination of subbands that can be selected is

to be. A combination of 2024 subbands can be represented by 11 bits and can be used to feed back a selected subband index. However, the number of bits required depends on the bandwidth and the number of selected subbands.

Alternatively, all bandwidths may be configured to have the same number of subband sets regardless of the bandwidth. Therefore, the number of subbands included in one subband set varies depending on the bandwidth. For example, if the total number of subband sets is 12, one subband set includes 0.5 subbands at 5 MHz bandwidth, one subband at 10 MHz bandwidth, and two subbands at 20 MHz bandwidth. . The UE measures the feedback information and selects at least one of the configured subband sets to feed back the feedback information measured for the corresponding subband set. However, when one subband set includes two subbands in a 20 MHz bandwidth, feedback information may not be accurately measured if two corresponding subbands belong to different frequency partitions. Accordingly, in the case of the 20 MHz bandwidth, like the 10 MHz bandwidth, one subband set includes one subband, but a subband may be selected only from 12 subband sets out of 24 subband sets. Since feedback information of adjacent subbands in a frequency partition having the same transmit power level may have a similar value, the subband set is composed of only subband sets having an odd or even index among the subband sets, thereby forming the entire subband. You can configure the number of sets to 12. Alternatively, feedback on subband sets of even indexes or subband sets of odd indexes may be alternately transmitted on the time axis.

In addition, when the entire bandwidth is divided into a plurality of frequency partitions, feedback information may be measured only for subbands belonging to a specific frequency partition, and feedback information for M subbands selected from these may be fed back. When the number of total subband sets is S and the number of subband sets belonging to a specific frequency partition is P, the feedback information of M selected subbands of the S total subband sets is measured and the specific frequency partition among them. Feedback information on subbands belonging to the UE may be fed back. Alternatively, feedback information on a set of P subbands may be measured, and feedback information on M selected subbands may be fed back. Selecting M subbands from P subband sets can reduce signaling overhead than selecting M subbands from S subband sets, but the number of transmitted bits also changes as P changes. There is this.

The specific frequency partition in which M subbands are selected may be notified by the base station through a feedback allocation A-MAP IE, or the terminal may directly select a specific frequency partition. When the terminal directly selects a specific frequency partition, it should inform the base station of the selected specific frequency partition using PFBCH encoding type 0 or 1. In this case, indexes 58 to 61 of the PFBCH encoding type 0 or 1 may be used. Table 12 is an example of reconfiguring the FPI field of the feedback allocation A-MAP IE of Table 1 when the base station informs the UE of a specific frequency partition.

If (MFM = 0,1,4,7) {    FPI [2] Frequency partition indication: ABS indicate AMS to send wideband CQI and STC rate of the frequency partition and reuse factor in the future:
0b00: Frequency partition index 0
0b01: Frequency partition index 1
0b10: Frequency partition index 2
0b11: Frequency partition index 3 }

That is, the base station can always inform the terminal through the feedback allocation A-MAP IE information on the frequency partition to be measured regardless of the MIMO feedback mode. The terminal transmits wideband feedback information of the frequency partition or narrowband feedback information including the subband index of the frequency partition according to the information on the transmitted frequency partition. If the subband set includes subbands belonging to frequency partitions other than the frequency partition for which feedback is to be measured, only feedback information of the subbands belonging to the frequency partition for which feedback is to be measured may be fed back. That is, when the same number of subband sets are configured regardless of the bandwidth and one subband set includes two subbands according to a 20 MHz bandwidth, feedback information according to the configuration of frequency partitions to which the two subbands belong, respectively. May be configured differently. For example, if both subbands constituting the subband set belong to a selected specific frequency partition, the UE transmits measured feedback information for both subbands. When only one subband belongs to the selected specific frequency partition, the UE transmits feedback information for one subband belonging to the selected specific frequency partition among feedback information for the measured two subbands. If both subbands do not belong to the selected specific frequency partition, the measured feedback information may not be transmitted.

In addition, the subband may be mapped to a CLRU or DLRU, wherein a subband requiring narrowband feedback information is a subband mapped to CLUR, and wideband feedback information rather than narrowband feedback information for the subband mapped to the DLRU. Measure Accordingly, the feedback information may be measured only for the subbands mapped to the CLRU, and the feedback information for the selected M subbands may be fed back. When the total number of subband sets is S and the number of subband sets mapped to CLRU is G, the feedback information about M selected subbands of the S subband sets is measured and the submaps are mapped to CLRU among them. Feedback information of subbands belonging to the band set may be fed back. Alternatively, the feedback information for the G subband set may be measured and the feedback information for the M selected subbands may be fed back. Selecting M subbands from G subband sets can reduce signaling overhead than selecting M subbands from S subband sets, but the number of transmitted bits also changes as G changes. There is this. If a subband mapped to a CLRU and a subband mapped to a DLRU exist at the same time in a subband set, only feedback information of a subband mapped to a CLRU to measure feedback may be measured and fed back.

Alternatively, the proposed invention may be applied in combination. For example, in selecting a subband among a set of subbands belonging to a specific frequency partition, only a subband mapped to a CLRU may be selected. On the contrary, in selecting a subband among subband sets mapped to the CLRU, only subbands belonging to a specific frequency partition may be selected.

12 is a block diagram illustrating a base station and a terminal in which an embodiment of the present invention is implemented.

The base station 800 includes a processor 810, a memory 820, and a radio frequency unit (RF) 830. Processor 810 implements the proposed functions, processes, and / or methods. Processor 810 processes the feedback assignment A-MAP IE. Layers of the air interface protocol may be implemented by the processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 to transmit and / or receive a radio signal and to transmit the feedback allocation A-MAP IE.

The terminal 900 includes a processor 910, a memory 920, and an RF unit 930. Processor 910 implements the proposed functions, processes, and / or methods. The processor 910 selects the at least one subband from among a plurality of subbands constituting the subband set. The feedback information includes an index of the at least one subband, and the at least one subband may be selected in consideration of a frequency partition or resource mapping of the plurality of subbands. The feedback transmission method proposed by the terminal of FIG. 12 may be implemented. In addition, layers of the air interface protocol may be implemented by the processor 910. The RF unit 930 is connected to the processor 910 to transmit the feedback information measured for the at least one subband. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910.

Processors 810 and 910 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory 820, 920 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. The RF unit 830 and 930 may include a baseband circuit for processing a radio signal. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module may be stored in the memory 820, 920 and executed by the processor 810, 910. The memories 820 and 920 may be inside or outside the processors 810 and 910, and may be connected to the processors 810 and 910 by various well-known means.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (15)

In the feedback transmission method in a wireless communication system,
Select at least one subband from among a plurality of subbands constituting the subband set,
Transmitting feedback information measured for the at least one subband,
The feedback information includes an index of the at least one subband,
The at least one subband is selected in consideration of a frequency partition or resource mapping of the plurality of subbands. The method of claim 1,
The at least one subband is selected from the entire subband set,
And wherein the at least one subband belongs to a selected specific frequency partition. The method of claim 2,
The information on the specific frequency partition is signaled by a feedback allocation Advanced-MAP (A-MAP) Information Element (IE). The method of claim 2,
The specific frequency partition is selected by the terminal, characterized in that the feedback transmission method. The method of claim 4, wherein
And information on the specific frequency partition is fed back to the base station by Primary Fast Feedback Channel (PFBCH) encoding type 1. The method of claim 1,
The at least one subband is selected from a set of subbands belonging to a specific frequency partition. The method of claim 1,
The at least one subband is selected from the entire subband set,
The at least one subband belongs to a subband set mapped to a Contiguous Logical Resource Unit (CLRU). The method of claim 1,
And the at least one subband is selected from a set of subbands mapped to a CLRU. The method of claim 1,
The feedback information is transmitted to the base station through a Primary Fast Feedback Channel (PFBCH) or Second Fast Feedback Channel (SFBCH). A feedback transmission device in a wireless communication system,
An RF unit for transmitting feedback information measured for at least one subband; And
And a processor connected to the RF unit and configured to select the at least one subband from among a plurality of subbands constituting a subband set.
The feedback information includes an index of the at least one subband,
The at least one subband is selected in consideration of a frequency partition or a resource mapping of the plurality of subbands (resource mapping). The method of claim 10,
The at least one subband is selected from the entire subband set,
And the at least one subband belongs to a selected specific frequency partition. The method of claim 10,
And the at least one subband is selected from a set of subbands belonging to a specific frequency partition. The method of claim 10,
The at least one subband is selected from the entire subband set,
And the at least one subband belongs to a subband set mapped to a contiguous logical resource unit (CLRU). The method of claim 10,
And the at least one subband is selected from a set of subbands mapped to a CLRU. The method of claim 10,
And the feedback information is transmitted to a base station through a primary fast feedback channel (PFBCH) or a secondary fast feedback channel (SFBCH).

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