TWI444000B - Method and apparatus for transmitting feedback request and method and apparatus for receiving feedback request in wireless communication system - Google Patents

Description

Method and device for transmitting feedback request in wireless communication system and method and device for receiving feedback request

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

The IEEE (American Institute of Electrical and Electronics Engineers) 802.16e standard was rewritten in 2007 as the name "WMAN-OFDMATDD" as an ITU-R (ITU-Radio communication sector) attached to the ITU (International Telecommunication Union). ITU-Radio Communications Division's IMT (International Mobile Telecommunication)-2000 sixth standard. ITU-R prepares an IMT advanced system as the next generation 4G mobile communication standard after IMT-2000. The IEEE 802.16WG (Working Group) has decided to launch an 802.16m project with the goal of generating the current IEEE 802.16e revised standard as the standard for IMT advanced systems in the late 2006. As can be noted from this purpose, the 802.16m standard relates to the continuity of the past 802.16e standard and the continuity of future next-generation IMT advanced systems. Therefore, the 802.16m standard is required to meet the advanced needs for advanced IMT systems while maintaining compatibility with mobile WiMAX systems based on the 802.16e standard.

A MIMO (Multiple Input Multiple Output) can be considered as a technology for supporting a reliable high speed data service. MIMO technology improves data transmission and reception efficiency by using multiple transmission antennas and multiple receive antennas. MIMO technology includes spatial multiplexing, transmit diversity, beamforming, or the like. The MIMO channel matrix is detachable into a plurality of independent channels according to one of the receiving antenna and the number of transmitted antennas. Each individual channel is called a layer or stream. The number of layers is called rank.

A user equipment (UE) can transmit feedback through the uplink. The feedback can include channel information required for data transmission. A base station (BS) can schedule radio frequency resources and transmit data by using feedback received from the UE. A closed loop scheme transmits data by compensating channel information included in the feedback from the UE, and an open loop scheme does not compensate for channel information included in the feedback from the UE. The feedback may not be transmitted in the open loop scheme, and if so, the BS may not be able to use the channel information included in the feedback. In general, in a wireless communication system, an open loop scheme can be applied to a one-channel environment for a UE moving at high speed; and a closed loop scheme can be applied to a one-channel environment, which is used for one UE moving at low speed. Since the channel for the UE moving at high speed is severely changed, and the channel information included in the feedback is unreliable, an open loop scheme is used. The channel environment for UEs moving at low speeds does not change substantially, so the channel information included in the feedback is reliable and less susceptible to delays, so a closed loop scheme can be used.

The BS transmits a feedback request, and the UE transmits the appropriate feedback information to the BS by using the control information included in the feedback request. For example, in IEEE 802.16, the BS transmits a feedback request called a Feedback Polling A-MAP IE. This feedback request is generally transmitted by a limited number of bits. However, it is possible that the conventional feedback polling A-MAP IE specified in IEEE 802.16 may include the number of bits exceeding the limited number of bits.

Therefore, there is a need for a method and apparatus for reducing the administrative burden when a BS transmits a feedback request without exceeding the limit number of bits.

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

According to an aspect of the present invention, a method for transmitting a feedback request in a wireless communication system is provided, the method comprising: transmitting feedback request control information to a user equipment (UE), wherein the feedback request control information includes a MIMO (Multiple Input Multiple Output) feedback bit map indicating at least one MIMO feedback mode to be applied to the UE and a common parameter, and the common parameter includes jointly requesting the UE to generate feedback information according to the at least one MIMO feedback mode One of the parameters.

When the channel state information based on the primary band is transmitted in the MIMO feedback mode, the common parameter may indicate a parameter that is the number of secondary bands used to generate the channel state information.

When the MIMO feedback mode is a closed loop feedback mode, the common parameters may include parameters indicating a codebook for selecting one of the PMIs to be fed back by the UE.

The feedback request control information can be unicast to the UE.

The MIMO feedback bit map can be composed of 8 bits.

The feedback request control information may include a 16-bit cyclic redundancy check (CRC).

According to another aspect of the present invention, a method for receiving a feedback request from a user equipment (UE) in a wireless communication system, the method comprising: receiving feedback request control from a base station (BS) And controlling the information transmission feedback information to the BS based on the feedback request, wherein the feedback request control information includes a MIMO (Multiple Input Multiple Output) feedback bit map indicating at least one MIMO feedback mode to be applied to the UE and one a common parameter, and the common parameter includes a parameter that jointly requests the UE to generate feedback information according to the at least one MIMO feedback mode.

When the channel state information based on the primary band is transmitted in the MIMO feedback mode, the common parameter may indicate a parameter that is the number of secondary bands used to generate the channel state information.

When the MIMO feedback mode is a closed loop feedback mode, the common parameters may include parameters indicating a codebook for selecting one of the PMIs to be fed back by the UE.

The feedback request control information can be unicast from the BS to the UE.

The MIMO feedback bit map can be composed of 8 bits.

The feedback request control information may include a 16-bit cyclic redundancy check (CRC).

According to still another aspect of the present invention, there is provided an apparatus for transmitting a feedback request in a wireless communication system, the apparatus comprising: an RF unit configured to transmit and receive a radio signal; and a process Connected to the RF unit, wherein the processor generates feedback request control information, and the feedback request control information includes a MIMO (Multiple Input Multiple Output) feedback bit map indicating at least one MIMO feedback mode to be applied to the UE And a common parameter, and the common parameter includes a parameter that jointly requests the UE to generate feedback information according to the at least one MIMO feedback mode.

When the channel state information based on the primary frequency band is transmitted in the MIMO feedback mode, the common parameter may indicate a parameter as the number of secondary frequency bands used to generate the target of the channel state information.

When the MIMO feedback mode is a closed loop feedback mode, the common parameters may include parameters indicating a codebook for selecting one of the PMIs to be fed back by the UE.

According to an exemplary embodiment of the present invention, the management burden of the feedback request transmitted by a BS can be reduced, and the feedback request can be maintained within a limited number of bits specified in the system.

The following techniques can be used in various wireless communication systems, such as CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC- FDMA (single carrier-frequency division multiple access) and the like. CDMA can be implemented as one of the radio frequency technologies such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA can be implemented as a radio frequency technology such as GSM (Global System for Mobile Communications) / GPRS (General Packet Radio Service) / EDGE (GSM Evolution Enhanced Data Rate). OFDMA can be implemented as a radio frequency technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, E-UTRA (Evolved UTRA), and the like. IEEE 802.16m is an upgrade of IEEE 802.16e that provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of the UMTS (Universal Mobile Telecommunications System). 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) using E-UTRA, which uses OFDMA for the downlink and SC-FDMA for the uplink. LTE-A (Advanced) is an upgrade of 3GPP LTE.

In order to clarify the explanation, this document will mainly be based on IEEE 802.16m, but the technical concept of the present invention is not limited thereto.

Figure 1 illustrates a wireless communication system.

Referring to FIG. 1, the wireless communication system 10 includes at least one base station (BS) 11. Each BS 11 provides a communication service to a specific geographic area (commonly referred to as cells) 15a, 15b, and 15c. Each of the cells can be divided into a plurality of regions (sectors). A User Equipment (UE) 12 may be fixed or mobile and may be referred to by other terms such as a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), Wireless components, personal digital assistants (PDAs), wireless data sets, handheld components, and more. BS 11 generally refers to a fixed station that communicates with UE 12 and may be referred to by other terms such as evolved Node B (eNB), Base Transceiver System (BTS), Access Point (AP), and the like.

A UE belongs to a cell, and the cell to which the UE belongs is called a serving cell. A BS that provides a communication service to a serving cell is called a serving BS. A wireless communication system is a cellular system so that it can have a different cell adjacent to the service unit. The different cells that are contiguous with the service unit are called a neighboring cell. A BS that provides a communication service to neighboring cells is called a neighboring BS. The serving cell and the neighboring cell are relatively determined based on the UE.

Techniques can be used for the downlink or uplink. In general, the downlink refers to communication from the BS 11 to the UE 12, and the uplink refers to communication from the UE 12 to the BS 11. In the downlink, a transmitter can be part of the BS 11 and a receiver can be part of the UE 12. In the uplink, a transmitter can be part of the UE 12 and a receiver can be part of the BS 11.

Figure 2 illustrates an example of a hyperframe structure.

Referring to FIG. 2, a hyperframe (SF) includes a hyperframe header (SFH) and four frames (F0, F1, F2, and F3). The lengths of the individual frames in the frame can be equal. It has been shown that each hyperframe has a size of 20 ms and each frame has a size of 5 ms, but the invention is not limited thereto. The length of the hyperframe, the number of frames included in the hyperframe, and the number of sub-frames included in each frame are variably changed. The number of subframes included in each frame can be variably changed according to the channel bandwidth and the length of a cyclic preamble (CP).

The frame includes a plurality of subframes SF0, SF1, SF2, SF3, SF4, SF5, SF6 and SF7. Each subframe can be used for an uplink or downlink transmission. The primary frame includes a plurality of OFDM (Orthogonal Frequency Division Multiplexing) symbols or OFDMA (Orthogonal Frequency Division Multiple Access) symbols in a time domain, and includes a plurality of secondary carriers in a frequency domain. The OFDM symbol is expressed in one symbol period and may be referred to by other terms according to a multiple access scheme, such as an OFDMA symbol, an SC-FDMA symbol, and the like. The one-time frame may include five, six, seven or nine OFDM symbols, but this is merely illustrative and the number of OFDM symbols included in the primary frame is not limited thereto. The number of OFDM symbols included in the primary frame can be variably changed according to a channel bandwidth and a CP length. The type of the frame can be defined according to the number of OFDMA symbols included in the frame. For example, a type 1 subframe can be defined to include six OFDMA symbols, a type 2 subframe can be defined to include seven OFDMA symbols, and a type 3 subframe can be defined to include five OFDMA symbols. And a type 4 subframe can be defined to include nine OFDMA symbols. A frame can include the same type of subframe. Alternatively, the frame may include different types of subframes. That is, the number of OFDMA symbols included in each subframe of a frame may be the same or different. Alternatively, the number of OFDMA symbols of at least one frame in a frame may be different from the number of OFDM symbols included in other remaining frames in the frame.

A TDD (Time Division Duplex) scheme or an FDD (Frequency Division Duplex) scheme can be applied to a frame. In the TDD scheme, each frame is used for an uplink transmission or a downlink transmission at a different time at the same frequency. That is, the subframe in a frame according to the TDD scheme is divided into an uplink subframe and a downlink subframe in a time domain. A switching point represents a point at which a transmission direction is changed from an uplink to a downlink or from an uplink to an uplink, and the number of switching points in each frame according to the TDD scheme Can be 2. In the FDD scheme, the respective subframes are used for an uplink transmission or a downlink transmission at the same time according to different frequencies. That is, the subframe according to one of the FDD schemes is divided into an uplink subframe and a downlink subframe in a frequency domain. Uplink transmissions and downlink transmissions can occupy different frequency bands and can be performed simultaneously.

A Hyper Frame Header (SFH) can carry a basic system parameter and a system configuration information. The SFH can be positioned in the first frame of the frame. The SFH can occupy the last five OFDMA symbols of the first frame. The SFH can be classified into a primary SFH (P-SFH) and a primary SFH (S-SFH). P-SFH and S-SFH can be transmitted at each superframe. The S-SFH can be transmitted in two connected subframes. The information transmitted in the S-SFH can be divided into three sub-packets of S-SFH SP1, S-SFH SP 2 and S-SFH SP 3. Each packet can be transmitted periodically by different cycles. The importance of information transmitted over S-SFH SP1, S-SFH SP 2 and S-SFH SP 3 can be different, and S-SFH SP1 can be used for the shortest period transmission, while S-SFH SP3 can be used for the longest period transmission. S-SFH SP1 includes information about network re-entry. S-SPH SP2 includes information about an initial network entry and a network discovery. S-SPH SP3 includes other remaining important system information. Figure 3 illustrates an example of an uplink resource structure.

Each uplink subframe can be divided into at least one frequency partition (FP). Figure 3 shows the case where the primary frame is divided into two frequency partitions FP 1 and FP 2, but the number of frequency partitions in the secondary frame is not limited. The number of frequency partitions can be up to 4. Each frequency partition includes at least one physical resource unit (PRU) on the entire OFDMA symbol available in the primary frame. Additionally, each frequency partition may include a connected/region and/or a distributed PRU. Each frequency partition can be used as a different use, such as a fractional frequency reuse (FFR). In FIG. 3, the second frequency partition FP2 includes a continuous resource configuration and a distributed resource configuration. "Sc" refers to the secondary carrier.

The PRU is a basic physical unit used for resource configuration, including the number of Pscs of the connected secondary bearers and the number of Nsyms of the connected OFDMA symbols. Psc can be 18. Nsym can be equal to the number of OFDMA symbols included in the primary frame. Therefore, Nsym can be determined according to the type of the frame. For example, when a subframe includes six OFDMA symbols, the PRU can be defined to include 18 subframes and 6 OFDMA symbols.

A logical resource unit (LRU) is a basic logical unit for a distributed and continuous resource configuration, and includes the number of Pscs of the secondary bearers and the number of Nsyms of the OFDMA symbols. The size of the LRU used for transmission of a control channel is equal to the size of the LRU for a data transmission. A plurality of users can share a control LRU. Additionally, the LRU can include a pilot. Therefore, the appropriate number of secondary carriers in an LRU depends on the number of configured pilots and the presence of a control channel.

A distributed logical resource unit (DLRU) can be used to obtain a frequency diversity gain. The DLRU includes a group of distributed secondary bearers in a frequency partition. The size of the DLRU is equal to the size of a PRU. The smallest unit tile used to form a DLRU, and the size of an uplink tile is 6 times the carrier multiplied by the NsymOFDMA symbol. Nsym can vary depending on the type of frame.

A Connected Logical Resource Unit (CLRU) can be used to obtain a frequency selective scheduling gain. The CLRU includes a group of connected secondary carriers. The size of the CLRU is equal to the size of a PRU.

Hereinafter, a control channel for transmitting a control signal or a feedback signal will now be described. A control channel can be used to transfer various types of control signals for communication between a base station (BS) and a user equipment (UE). A control channel described below can be applied to an uplink control channel and a downlink control channel.

Consider the following points to design the control channel.

(1) A plurality of micro-bricks included in a control channel may be distributed to a time domain or a frequency domain to obtain a frequency diversity gain. For example, when considering that a DLRU includes three micro-branches (each comprising six consecutive secondary carriers on six OFDM symbols), the control channel includes three micro-bricks and the individual micro-bricks can be distributed to the frequency or time domain. In addition, the control channel may include at least one micro-brick, one micro-brick may include a plurality of mini micro-bricks, and the mini micro-bricks may be distributed to the frequency domain or the time domain. For example, mini micro bricks can be configured as (OFDM symbol x times carrier) = 6x6, 3x6, 2x6, 1x6, 6x3, 6x2, 6x1 and the like. When it is assumed that one of the micro-bricks having one PUSC structure of IEEE 802.16e (OFDM symbol x times carrier) = 3x4 is controlled by a FDM (frequency division multiplexing) scheme, the mini micro brick can be Configured as (OFDM symbol x times carrier) = 6x2, 6x1 or the like. The mini micro brick can be configured to be (OFDM symbol x times carrier) = 6x2, 3x6, 2x6, 1x6 or the like only when considering a control channel including mini micro bricks.

(2) In order to support a high speed UE, the number of OFDM symbols constituting a control channel must be minimized. For example, three or fewer OFDM symbols constituting a control channel suitably support a UE at a movement of 350 km/h.

(3) There is a limitation in the transmission power of each symbol of a UE, and in order to increase the transmission power of each symbol of the UE, a larger number of OFDM symbols constituting a control channel is advantageous. Therefore, the appropriate number of OFDM symbols must be determined in consideration of the transmission power of each symbol of the high-speed UE of (2) and the transmission power of each symbol of the UE of (3).

(4) For coherent detection, the pilot sub-carriers used for one-channel evaluation must be evenly distributed to the time or frequency domain. Coherent detection is a method of obtaining data included in a data secondary carrier after evaluation by using a pilot implementation channel. To increase the power of the pilot secondary carrier, the number of pilots per OFDM symbol of the control channel must be equal to equally maintain the transmission power of each symbol.

(5) As for a non-coherent detection, the control signal must consist of an orthogonal code/sequence or a half orthogonal code/sequence, or can be expanded.

The uplink control channel may include an FFBCH (Fast Feedback Channel), a HARQ feedback channel (HFBCH; a hybrid automatic repeat request feedback channel), a metric channel, a BRCH (Bandwidth Request Channel), and the like. Information such as a CQI, a MIMO feedback, an ACK/NACK, an uplink synchronization signal, a bandwidth request, and the like can be transmitted via the uplink control channel. The FFBCH, HFBCH, metric channel, BRCH, and the like can be located in any area of the uplink subframe or frame.

The uplink control channel can be configured through downlink control information transmitted from the downlink of the BS. The downlink control information may be broadcast to each UE or may be transmitted to each UE through a unicast service. The aforementioned P-SFH or S-SFH is a broadcast downlink control signal, and a plurality of A-MAP IEs (Advanced MAP Information Elements) can be defined as an essential element for controlling a unicast service.

Figure 4 illustrates the process of signaling between a BS and a UE in accordance with an exemplary embodiment of the present invention.

Referring to FIG. 4, the BS requests feedback from the UE (S100). In order to schedule the MIMO feedback transmission of the UE, the BS may transmit one of the plurality of A-MAP IEs to the polling A-MAP IE to the UE. That is, the BS can request MIMO feedback (hereinafter referred to as "feedback") by transmitting a feedback polling A-MAP IE to the UE. In this case, the BS may unicast the feedback polling A-MAP IE to the UE. Then, the UE may transmit the feedback information to the BS according to the content of the feedback polling A-MAP IE by using a MAC control message or a MAC signaling header (S200).

Table 1 is an example of a conventional feedback polling A-MAP IE.

The respective fields (parameters) constituting the feedback polling A-MAP IE in Table 1 are defined as follows.

-Polling_sub_type: It indicates an uplink resource configuration or de-configuration, or a feedback modal configuration or de-configuration. "Polling_sub_type" can be composed of one bit and is set to 0 or 1. When "Polling_sub_type" is set to 0, a dedicated uplink (UL) configuration is included in the feedback polling A-MAP IE. The dedicated uplink configuration can be used to transmit feedback information in a feedback transmission frame defined in the Feedback Polling A-MAP IE. When "Polling_sub_type" is set to 1, the feedback polling A-MAP IE does not include a dedicated UL configuration. In this case, the UE may transmit the feedback information by using a dedicated UL configuration specified in a previous feedback polling A-MAP IE. That is, the BS may inform the UE whether to configure uplink resources through a current feedback polling A-MAP IE or whether to perform feedback by using the uplink resources configured in the previous feedback polling A-MAP IE.

-Allocation Duration(d): This indicates a valid interval for configuration. The configuration is valid for 2 ^(d-1) hyperframes starting from the hyperframe defined by the configuration association. When the "d" value is 0, it indicates that the feedback is deconfigured, so a previous scheduled feedback header transmission is released. When the "d" value is a binary number "111" (i.e., 7) indicating the feedback configuration, the previous schedule feedback header transmission is valid until a release command is received from the BS.

- Resource Index: This identifies the resource index for a previously assigned contiguous resource that has been deconfigured.

-HFA: It configures a HARQ feedback channel to confirm a successful reception of the polling A-MAP IE.

-I _sizeOffset : This indicates an offset value used to calculate a burst size index.

- MEF: It informs about the MIMO encoder format used for one uplink feedback transmission. Non-adaptive precoding can be used by the UE.

- LongTTI Indicator: This indicates the number of AAI subframes that are expanded by the configuration resource.

-HFA: This is an index used for a HARQ feedback configuration.

-ACID: It is a HARQ channel identifier.

-MFM_allocation_index: It consists of 2 bits, and when it is "0b00", it indicates that MFM0 has a measurement method indication=0. MFM stands for MIMO feedback mode, which can be referred to Table 2 (to be described). When it is "0b01", it indicates that MFM 3 has all sub-bands. When it is "0b10", it indicates that MFM 6 has all sub-bands, and when it is "0b11", MFM is polling A. -MAP IE is defined, where polling_subtype=1.

-Period: It indicates a short period of feedback (p-frame) and a long period (q-frame). When q is greater than 0, the feedback information according to a MIMO feedback mode indicated in an MFM_allocation_index is configured with a short period, and a correlation matrix is configured with a long period.

- MIMO_feedback_IE_type: It indicates whether it is a single BS MIMO feedback request or a multiple BS MIMO feedback request.

- MFM_bitmap: It consists of 8 bits and indicates a MIMO Feedback Mode (MFM).

MaxMt: It indicates a maximum rank or a reference rank (if multi-user MIMO) for feedback (if single-user MIMO).

Num_best_subbands: This indicates the number of optimal sub-bands that are fed back according to a feedback mode.

Codebook_coordination: This indicates searching for a PMI (Predecode Matrix Index) from those codebook elements.

-Codebook_subset: It indicates whether the PMI is reported from a basic codebook (or a converted basic codebook) or from a codebook subset (or a converted codebook subset).

-Measurement Method Indication: It indicates the intermediate code used for CQI measurement (when the value of Measurement Method Indication is 0b0) or pilot (when the value of Measurement Method Indication is 0b1).

Table 2 below shows an example of a MIMO feedback mode (MFM) and thus a supported MIMO transmission mode.

Referring to Table 2, the supported MIMO transmission modes differ according to the respective MIMO feedback modes. For example, a MIMO feedback mode 0 supports one of OL-SU (Open Loop-Single User) MIMO environments SFBC (Spatial Frequency Block Code) and SM (Spatial Multiplex) in a diversity arrangement. The UE measures a wideband CQI for SFBC and SM, and reports a CQI and STC (spatial time coding) rate to the BS.

A MIMO feedback mode 1 is used for an OL-SU CDR (conjugate data repetition) having an IF STC rate of 1/2 in the diversity arrangement.

A MIMO feedback mode 2 is used for OL-SU SM of one frequency selection schedule in an area arrangement. An STC rate indicates the number of preferred MIMO streams for one of the SMs. The primary band CQI corresponds to a selected rank.

A MIMO feedback mode 3 supports a CL-SU (closed loop single user) MIMO environment for a frequency selection schedule in a regional arrangement.

A MIMO feedback mode 4 is used for CL-SU MIMO using wide beamforming. The UE feeds back a wideband CQI. The UE estimates a wideband CQI based on a short-term or long-term precoding of the BS based on a feedback period. The BS obtains channel status information through feedback of a correlation matrix or feedback of a broadband PMI.

A MIMO feedback mode 5 supports an OL-SU (Open Loop Multiple User) MIMO environment for a frequency selection schedule in an area arrangement.

A MIMO feedback mode 6 supports a CL-MU (Closed Loop Multiple User) MIMO for a frequency selection schedule in a regional arrangement. The UE selects the primary frequency band and feeds back a corresponding CQI and primary frequency band PMI. The primary band CQI refers to a CQI of an optimal PMI in the primary band. To estimate a PMI in a primary band, a rank 1 codebook (or a subset of the codebook) is used.

A MIMO feedback mode 7 uses wideband beamforming to support one of the CL-MU MIMO environments in a diversity arrangement.

When the BS transmits the aforementioned feedback polling A-MAP IE to the UE, it includes a CRC (Cyclic Redundancy Check) therein. The CRC can be composed of 16 bits, and the UE can detect an error through the CRC. When the feedback polling A-MAP IE is configured to include CRC bits, the most bits that can be transmitted by the BS can be limited. For example, in IEEE 602.16m, the feedback polling A-MAP IE must be configured to no more than 56 bits.

However, the aforementioned conventional feedback polling A-MAP IE has the following problems.

1. When "Polling_sub_type" is 0 (ie, 0b0) and includes 16 CRC bits, it is more than 56 bits (in detail, it is transmitted by 58 bits).

2. When "Polling_sub_type" is 1 (ie, 0b1), depending on how a "MFM_bitmap" is set in the case of a single BS MIMO feedback request, it may exceed 56 bits. Therefore, there is a need to reduce a configuration method of polling the management burden of the A-MAP IE.

First, when "Polling_sub_type" is 0, the following four methods can be considered.

The first method: delete the MEF field (parameter).

The MEF field indicates one of the MIMO encoder formats for an uplink feedback transmission and can be composed of 2 bits. SFBC (Spatial Frequency Block Code), Vertical Coding, CSM (Cooperative Spatial Multiplex Conversion) or the like is expressed in terms of MEF field values. When "Polling_sub_type" is 0, the MEF field can be excluded to SFBC only or one antenna transmission by limiting a MIMO encoder format for an uplink feedback transmission. In this way, the total number of feedback polling A-MAP IE bits may meet the 56-bit limit.

The second method: reduce the number of bits in the MEF field and reduce the resource index to 10 bits.

The MEF field consists of 2 bits, and when the value is 2, it indicates a CSM with TNS=2, Mt=1 and SI=1, and when the value is 3, it indicates that one has TNS=2, Mt CSM with =1 and SI=2. Here, the TNS (the total number of streams) is the total number of streams used in one of the LRUs of the CSM, and the Mt is the number of streams in a transmission according to Nt (the number of BS transmission antennas), and the SI is used for the CSM. A first pilot index. In this case, the MEF field can be reduced to 1 bit by excluding the CSM option. In addition, the resource index field can be reduced to 10 bits to meet the limit of the total number of feedback polling A-MAP IE bits to 56 bits.

The third method: only use "Polling_sub_type" for resource configuration.

According to this method, the "MFM_allocation_index" field, the "MaxMt" field, and the "Period" field can be removed, so the total number of feedback polling A-MAP IE bits can be limited to 56 bits.

The fourth method: remove the "MaxMt" field and modify the "MFM_allocation_index" field and the "Period" field.

Table 3 below shows an example of the modification of the "MFM_allocation_index" field and "Period" in the fourth method.

Referring to Table 3, when the value of the "MFM_allocation_index" field is "0b00", the measurement method indicates that the system 0 and the indication have a MIMO feedback mode (MFM) 0 of "MaxMt" = 1, when the value of the "MFM_allocation_index" field is When "0b01" is selected, the measurement method indicates that the system 0 and the indication have a MIMO feedback mode 0 of "MaxMt" = 2, and when the value of the "MFM_allocation_index" field is "0b10", it indicates a common variation matrix feedback, and When the value of the "MFM_allocation_index" field is "0b11", the MIMO feedback mode is defined when "Polling_sub_type" is 1.

The conventional feedback polling A-MAP IE in Table 1 includes the fields "MFM_allocation_index", "MaxMt", and "Period". When the meaning of the "MFM_allocation_index" field is modified as shown in Table 3, the "MaxMt" field can be removed. In this way, the 56-bit limit of the polling A-MAP IE can be maintained.

Hereinafter, a method of limiting the total number of feedback polling A-MAP IE bits to 56 bits or less when the value of the "Polling_sub_type" field is 1 will be described.

When the value of the "Polling_sub_type" field is 1 and "MIMO_feedback_IE_type" is 0 (ie, it means a feedback configuration for single-base station MIMO operation), the total number of feedback polling A-MAP IE bits is based on "MFM_bitmap" The setting may exceed 56 bits. For example, suppose the value of the "MFM_bitmap" field is "00110010". In addition, it is assumed that a first bit in the bit stream is LSB#0 and the last bit LSB#7. That is, the case where the MIMO feedback modes 2, 3, and 6 are indicated by "MFM_bitmap". Referring to Table 1, including the CRC in the conventional feedback polling A-MAP IE, the total number of transmitted bits is 61 bits, more than 56 bits (MFM2 requires 5 bits, MFM3 requires 6 bits, and MFM6 needs Six bits, and in this case, the "MaxMt" and "Num_best_subbands" fields are included in each MFM).

In an effort to overcome this problem, a method for classifying and using parameters (referred to as common parameters) that can be used together for at least one MIMO feedback mode in the parameters for the respective MIMO feedback modes can be considered. state. The common parameters may be parameters that are typically required for the UE to generate feedback information in a plurality of MIMO feedback modalities.

Figure 5 is a flow diagram illustrating the process of configuring a feedback polling A-MAP IE in accordance with an exemplary embodiment of the present invention.

Referring to Fig. 5, when "Polling_sub_type" is 1 (S50) and "MIM_feedback_IE_type" is 0 (S51), the BS uses the common parameter (field) for mutually different MIMO feedback modes (S53). When the common parameters are used in combination by a plurality of MFMs instead of being separately included according to the respective MFMs, the total number of feedback polling A-MAP IE bits can be reduced.

Table 4 below shows an example of the classification of common parameters that can be used in conjunction with MIMO feedback modalities.

In Table 4, a "Num_best_subbands" parameter (or field) is included in both MFMs 2, 3, 5, and 6. That is, when the MIMO feedback mode requests channel state information based on the sub-band, the "Num_best_subbands" parameter may be a parameter indicating a number of sub-bands as a target of channel state information generation.

When the MIMO feedback mode is a closed loop feedback mode, a "Codebook_cordination" parameter and a "Codebook_subset" parameter may be a parameter indicating a codebook for selecting a PMI to be fed back by the UE.

According to the example in Table 4, the total number of common parameter bits commonly used for a plurality of MIMO feedback modes may be 9 bits. In this case, the total number of feedback polling A-MAP IE bits is 53 bits (MFM1 can be used only in the OL area, and in this case, "MaxMt" and a measurement method have been determined, so it may not Notify the "Measurement Method Indication" parameter).

Table 5 below shows an example of one configuration of the feedback polling A-MAP IE when the parameters commonly used for the plurality of MFMs as described in Table 4 above are used and the fourth method is used.

Regarding Table 5, when LSB#0, LSB#2, or LSB#3 in the "MFM_bitmap" parameter is 1 (that is, in the case of a single-user MIMO with MFM0, MFM2, or MFM3), feedback polling A- The number of MAP IE bits can be reduced by using the "MaxMt" parameter together. In addition, when the LSB#2, LSB#3, LSB#5, or LSB# 6 in the "MFM_bitmap" parameter is 1 (that is, in the case of the primary band mode with MFM2, MFM3, MFM5, or MFM6), the feedback wheel The number of A-MAP IE bits can be reduced by using the "Num_best_subbands" parameter together. In addition, when LSB#3, LSB#4, LSB#6, or LSB#7 in the "MFM_bitmap" parameter is 1 (that is, in the case of a closed loop feedback mode with MFM3, MFM4, MFM6, or MFM7), The number of feedback polling A-MAP IE bits can be reduced by using the "Code_coordination" and "Codebook_subset" parameters together.

In the example of Table 5, all the parameters of Table 4 and the fourth method are applied for the sake of convenience, but the present invention is not limited thereto. That is, only some of the parameters of Table 4 (for example, "Num_best_subband", "Code_coordination", and "Codebook_subset" can be used as common parameters.

In the following, another example of keeping the total number of feedback polling A-MAP IE bits 56 bits will now be described. For example, the "MaxMt" parameter can be used in common depending on whether the MIMO mode using the MFM is OL MU-MIMO or CL MU-MIMO. That is, by using the common characteristics of the MFM indicated by "MFM_bitmap", the MFMs having the common characteristics collectively use the "MaxMt" parameter instead of including the "MaxMt" parameter separately in all the MFMs.

Table 6 below shows an example of the parameters that can be used together to classify, which is used when the "MaxMt" parameter is based on whether the MIMO mode is OL MU-MIMO or CL MU-MIMO.

In this case, the number of parameter bits that may be commonly used is a total of 11 bits, so that the number of feedback polling A-MAP IE bits is 55 bits. Therefore, it does not exceed the limit of 56 bits.

Table 7 below shows an example of the configuration of polling the A-MAP IE bit by using the common parameters of Table 6 and the feedback using the fourth method.

Figure 6 is a schematic block diagram of a BS and a UE according to an exemplary embodiment of the present invention.

The BS 800 includes a processor 810, a memory 820, and an RF (Radio Frequency) unit 830. Processor 810 implements the functions, processes, and/or methods set forth above. The processor 810 generates feedback request control information, such as a feedback polling A-MAP IE, and transmits it to the UE 900 via the RF unit 830. The feedback polling A-MAP IE includes a MIMO feedback bit map indicating at least one MIMO feedback mode and common parameters to be applied to the UE 900. The common parameter may be a common required parameter for the UE 900 to generate feedback information in at least one MIMO feedback mode. Layers of a radio interface interface may be implemented by processor 810. Memory 820 coupled to processor 810 stores various types of information for driving processor 810. The RF unit 830 connected to the processor 810 transmits and/or receives radio signals and transmits a feedback polling A-MAP IE.

The UE 900 includes a processor 910, a memory 920, and an RF unit 930. The RF unit 930 connected to the processor 910 receives the feedback polling A-MAP IE from the BS 800 and transmits a feedback signal. Processor 910 implements the functions, processes, and/or methods set forth above. The processor 910 processes the feedback polling A-MAP IE and generates feedback information. Layers of a radio interface interface may be implemented by processor 910. Memory 920 coupled to processor 910 stores various types of information for driving processor 910.

Processors 810 and 910 can include an ASIC (Application Specific Integrated Circuit), a different set of chips, logic circuitry, and/or an information processing component. The memory (820, 920) may include a ROM (read only memory), a RAM (random access memory), a flash memory, a memory card, a storage medium, and/or other storage elements. RF units 830 and 930 can include a baseband circuit for processing a radio signal. When a specific embodiment is implemented by software, the foregoing scheme may be implemented by a module (process, function, etc.) that performs the aforementioned functions. Modules may be stored in memory 820 and 920 and executed by processors 810 and 910. The memories 820 and 920 can be disposed within or external to the processors 810 and 910 or can be coupled to the processors 810 and 910 via a well-known unit.

In the foregoing exemplary systems, the methods have been described as sequential steps or blocks based on flowcharts, but the invention is not limited to the order of the steps and some of them may differ from the order of the foregoing steps or concurrently. In addition, those skilled in the art will understand that the steps are not excluded but include other steps, or one or more of the steps may be deleted without departing from the scope of the invention.

The present invention may be embodied in a number of forms without departing from the characteristics thereof, and it should be understood that the specific embodiments described above are not limited to the details described above, but should be broadly defined in the scope of the appended claims. All changes and modifications to the measurement and limitation, or the equivalent of such measurement and limitation, are therefore intended to be covered by the accompanying claims.

10. . . Wireless communication system

11. . . Base station/BS

12. . . User equipment/UE

15a. . . Cell

15b. . . Cell

15c. . . Cell

800. . . Base station/BS

810. . . processor

820. . . Memory

830. . . RF (radio frequency) unit

900. . . User equipment/UE

910. . . processor

920. . . Memory

930. . . RF unit

F0. . . Frame

F1. . . Frame

F2. . . Frame

F3. . . Frame

SF. . . Super frame

SFH. . . Super frame header 2

SF0. . . Secondary frame

SF1. . . Secondary frame

SF2. . . Secondary frame

SF3. . . Secondary frame

SF4. . . Secondary frame

SF5. . . Secondary frame

SF6. . . Secondary frame

SF7. . . Secondary frame

S50. . . step

S51. . . step

S52. . . step

Figure 1 illustrates a wireless communication system.

Figure 2 illustrates an example of a hyperframe structure.

Figure 3 illustrates an example of an uplink resource structure.

Figure 4 illustrates a signaling process between a base station (BS) and a user equipment (UE) in accordance with an exemplary embodiment of the present invention.

Figure 5 is a flow diagram illustrating the process of configuring a feedback polling A-MAP IE in accordance with an exemplary embodiment of the present invention.

Figure 6 is a schematic block diagram of a BS and a UE in accordance with an exemplary embodiment of the present invention.

S50. . . step

S51. . . step

S52. . . step

Claims (10)

A method for transmitting a feedback request, the method being performed by a base station (BS) in a wireless communication system, the method comprising the steps of: transmitting feedback request control information to a user equipment (user Equipment, UE), wherein the feedback request control information includes a Multi-Input Multi-Output (MIMO) feedback bit map indicating that the eight MIMO feedback modes are to be camped on At least one MIMO feedback modality and common parameters applied to the UE, wherein the eight different MIMO feedback modalities are classified as including four closed loop (CL) MIMO feedback modalities for a closed loop feedback and for An open loop feedback of four open loop (OL) MIMO feedback modalities, and the eight different MIMO feedback modalities are also classified as four subband CQI MIMO feedbacks that request a primary band channel quality indicator (CQI) a modality and four broadband CQI MIMO feedback modalities requesting a wideband CQI, wherein the common parameters are provided to at least two of the eight different MIMO feedback modalities, And wherein when the four CL MIMO feedback indicating at least one of the MIMO feedback mode bit image, such common parameter comprises a precoding matrix index for selecting one to be reserved on the UE by a parameter of a codebook of a (precoding matrix index, PMI), and wherein the common parameter includes an indication when the MIMO feedback bitmap map indicates at least one of the four sub-band CQI MIMO feedback modalities A parameter that is the number of sub-bands used to generate the target of the primary band CQI. The method of claim 1, wherein the feedback request control information is unicast to the UE. The method of claim 1, wherein the MIMO feedback bit map comprises 8 bits. The method of claim 1, wherein the feedback request control information comprises a 16-bit cyclic redundancy check (CRC). A method for receiving a feedback request from a user equipment (UE) in a wireless communication system, the method comprising the steps of: receiving feedback request control information from a base station (BS); and based on the feedback Requesting control information transmission feedback information to the BS, wherein the feedback request control information includes a multiple input multiple output (MIMO) feedback bit map indicating that to be applied to eight different MIMO feedback modes in eight different MIMO feedback modes At least one MIMO feedback modality and common parameters of the UE, wherein the eight different MIMO feedback modalities are classified as including four closed loop (CL) MIMO feedback for a closed loop feedback Modal and four open loop (OL) MIMO feedback modalities for an open loop feedback, and the eight different MIMO feedback modalities are also classified as containing four requests for a primary band channel quality indicator (CQI) a subband CQI MIMO feedback modality and four broadband CQI MIMO feedback modalities requesting a wideband CQI, wherein the common parameters are provided to at least two of the eight different MIMO feedback modalities, And wherein when the MIMO feedback bitmap map indicates at least one of the four CL MIMO feedback modalities, the common parameters include a precoding matrix index (precoding matrix index) for selecting to be fed back by the UE a parameter of a codebook of PMI) and wherein when the MIMO feedback bitmap map indicates at least one of the four sub-band CQI MIMO feedback modalities, the common parameters include an indication for generating once A parameter of the number of sub-bands of the target of the band CQI. The method of claim 5, wherein the feedback request control information is unicast from the BS to the UE. The method of claim 5, wherein the MIMO feedback bit map comprises 8 bits. The method of claim 5, wherein the feedback request control information comprises a 16-bit cyclic redundancy check (CRC). An apparatus for transmitting a feedback request in a wireless communication system, the apparatus comprising: a radio frequency (RF) unit configured to transmit and receive a radio signal; and a processor coupled to the RF unit, wherein the processor is configured to transmit a feedback request Controlling information to a user equipment (UE), wherein the feedback request control information includes a Multi-Input Multi-Output (MIMO) feedback bit map, the MIMO feedback bit map indication is at eight At least one MIMO feedback mode and common parameters to be applied to the UE in different MIMO feedback modes, wherein the eight different MIMO feedback modes are classified as comprising four closed loops for a closed loop feedback ( CL) MIMO feedback mode and four open loop (OL) MIMO feedback modes for an open loop feedback, and the eight different MIMO feedback modes are also classified as containing a request primary band channel quality indicator (CQI) Four sub-band CQI MIMO feedback modalities and four wideband CQI MIMO feedback modalities requesting a wideband CQI, wherein the common parameters are provided to at least the eight different MIMO feedback modalities MIMO feedback modalities, and wherein when the MIMO feedback bitmap map indicates at least one of the four CL MIMO feedback modalities, the common parameters include information regarding a precoding matrix for selecting to be fed back by the UE A parameter of a codebook (precoding matrix index (PMI)), and Wherein the MIMO feedback bit map indicates at least one of the four sub-band CQI MIMO feedback modalities, the common parameters include a parameter indicating a number of sub-bands as a target for generating a primary band CQI. An apparatus for receiving a feedback request in a wireless communication system, the apparatus comprising: a radio frequency (RF) unit configured to transmit and receive a radio signal; and a processor, the processor The processor is coupled to the RF unit, wherein the processor is configured to receive feedback request control information, wherein the feedback request control information comprises a Multi-Input Multi-Output (MIMO) feedback bit map, The MIMO feedback bitmap map indicates at least one MIMO feedback modality and common parameters to be applied to a user equipment (UE) in eight different MIMO feedback modalities, wherein the eight different MIMO feedback modalities are classified To include four closed loop (CL) MIMO feedback modalities for a closed loop feedback and four open loop (OL) MIMO feedback modalities for an open loop feedback, and the eight different MIMO feedback modalities Also classified into four sub-band CQI MIMO feedback modalities that request a primary band channel quality indicator (CQI) and four broadband CQI MIMO feedback modalities that request a wideband CQI, where the common parameters are It is provided to the Department of the eight different At least two MIMO feedback modes in the MIMO feedback mode, and wherein when the MIMO feedback bit map indicates at least one of the four CL MIMO feedback modes, the common parameters are related to selecting for to be fed back a parameter of a codebook of a precoding matrix index (PMI), and wherein when the MIMO feedback bit map indicates at least one of the four subband CQI MIMO feedback modalities, The common parameters include a parameter indicating the number of sub-bands that are the targets for generating the primary band CQI.