KR20130113986A - Method and apparatus for transmitting and receiving channel state information in downlink coordinated system - Google Patents

Abstract

PURPOSE: A CSI (channel state information) transceiving method in down link coordinated system and an apparatus thereof can generate aggregated CSI corresponding to a first CSI-RS (CSI-reference signal) and a second CSI-RI. CONSTITUTION: A transceiver (1010) receives a first CSI-RS corresponding to a first TP (transmission point). The transceiver receives a second CSI-RS corresponding to a second TP. A control unit (1040) generates aggregated CSI corresponding to the first CSI-RS and the second CSI-RS. The transceiver transmits the generated aggregated CSI. The control unit generates the aggregated CSI by using a transmission timing at which the aggregated CSI is transmitted. [Reference numerals] (1010) Transceiver unit; (1020) Channel estimation unit; (1030) Feedback generation unit; (1040) Control unit

Description

Method and apparatus for transmitting and receiving channel state information in downlink coordinated system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING CHANNEL STATE INFORMATION IN DOWNLINK COORDINATED SYSTEM}

The present invention relates to a method and apparatus for transmitting and receiving channel state information (CSI) in a Coordinated Multi-Point (CoMP) communication system.

The communication system includes a downlink (DL) and an uplink (UL). A downlink is a connection that transmits signals from one or more transmission points (TP) to user equipment (UE). The uplink is a connection for transmitting signals from one or more UEs to one or more reception points (RPs). A UE is usually also referred to as a terminal or a mobile station. The UE may be fixed or mobile. The UE may comprise, for example, a wireless device, a cellular telephone, a personal computer device. The TP or RP is typically a fixed station. TP and RP may be implemented as one integrated device, and a device incorporating TP and RP may be referred to as a base station. The base station may also be referred to as a base transceiver system (BTS), a node B, an enhanced Node B (eNB), an access point (AP)

The communication system supports the transmission of several signal types including data signals, control signals and reference signals. The data signal carries information content. The control signal enables proper processing of the data signals. The reference signal is also referred to as a pilot. The reference signal enables coherent demodulation of the data or control signals. When the reference signal is transmitted, channel state information (CSI) corresponding to an estimate of the channel medium may be generated based on the reference signal.

The UL data information is transmitted through a Physical Uplink Shared CHannel (PUSCH). Uplink Control Information (UCI) is a physical uplink control channel (PUCCH), except that the UE has a PUSCH transmission and the UE can transmit at least some UCIs along with the data information on the PUSCH. Control CHannel. The UCI includes ACK (acknowledgment) information associated with the use of a Hybrid Automatic Repeat reQuest (HARQ) process. The HARQ-ACK is responsive to the reception of transmission blocks (TB) by the UE in the downlink (DL) of the communication system, which corresponds to the signal transmission from the Node B to the UE.

DL TBs are transmitted on a physical downlink shared channel (PDSCH). The UCI may also include a channel quality indicator (CQI), a precoding matrix indicator (PMI), or a rank indicator (RI). The CQI, PMI, and RI may together be referred to as channel state information (CSI). The CQI provides the Node B with a measure of the signal-to-interference and noise ratio (SINR) experienced by the UE over subbands or over the entire operating DL bandwidth (BW; Bandwidth). This measure is typically in the form of the best modulation and coding scheme (MCS) that a preset BLER (BLER) can be achieved for transmission of TBs. The Node B may be notified via the PMI / RI how to combine signaling transmissions from the UE to Node B antennas in accordance with a Multiple-Input Multiple-Output (MIMO) scheme. The UE may transmit the UCI over the PUCCH separately from the data information. Alternatively, the UE may transmit the UCI along with the data information via the PUSCH.

The DL data information is transmitted via the PDSCH. The DL Control Information (DCI) may be used for a DL CSI feedback request to UEs, Scheduling Assignments (SAs) for PUSCH transmissions from UEs, or PDSCH receipts by UEs (DL < / RTI > SAs). SAs are carried in DCI formats transmitted via respective Physical Downlink Control Channels (PDCCHs). In addition to the SAs, the PDCCHs may carry a DCI that is common to all UEs, or common to a group of UEs.

1 shows a resource structure of LTE-A. The downlink transmission of LTE and LTE-A is performed in units of subframes in the time domain and in units of RBs in the frequency domain. The subframe is equal to 1 msec of the transmission period, but the RB is equal to 180 kHz of the transmission bandwidth composed of 12 subcarriers. As shown in FIG. 7, the system bandwidth of LTE-A is composed of a plurality of RBs in the frequency domain and a plurality of subframes in the time domain.

A number of different signals are transmitted for releases of LTE-A release 10 and releases 10 and later. For the downlink, the following reference signals are transmitted:

1. Cell specific reference signal (CRS): used for initial system access, paging, PDSCH demodulation, channel measurement, handover, etc.

2. Demodulation reference signal (DMRS): Used for demodulation of PDSCH.

3. Channel status information reference signal (CSI-RS): used for channel measurement

In addition to the reference signals, the zero power CSI-RS may be applied to the LTE-A release 10. The zero power CSI-RS may occur at the same time and frequency resources as the CSI-RS, but may differ from the CSI-RS in that no signal is transmitted on the REs that are subject to the zero power CSI-RS. have. The purpose of the zero power CSI-RS is to transmit on the resources used by adjacent TPs for the CSI-RS transmission of a particular TP and not to generate interference on these CSI-RSs transmitted by neighboring TPs will be.

2 is a configuration diagram of resources in an LTE or LTE-A system. Referring to FIG. 8, locations of resources used for transmission of different reference signals, PDSCH, zero power CSI-RS, and control channels are shown. It should be noted that Figure 8 is for a single RB in the frequency domain and for a single subframe in the time domain. For each subframe, there may be a plurality of RBs, and the signals may be transmitted on a plurality of RBs in a manner similar to that shown in Fig. The resources marked with alphabets A, B, C, D, E, F, G, H, I and J in Figure 8 correspond to locations where the transmission to the CSI- RS has four antenna ports . For example, for four REs marked 'A', a CSI-RS with four antenna ports may be transmitted. A CSI-RS with two antenna ports can be transmitted over the resources obtained by limiting the resources for the CSI-RS with four antenna ports to two. Additionally, a CSI-RS with eight antenna ports can be transmitted over the resources obtained by combining two resources for the CSI-RS with four antenna ports. The zero power CSI-RS may be applied to resources for the CSI-RS with four antenna ports.

In the downlink transmission mode 9 of 3GPP LTE-A Release 10, the UEs measure the CSI-RS transmitted by the eNB and transmit the RI (Rank Indicator), PMI (Precoding Matrix Indicator) and CQI (Channel Quality Indicator) And generates and / or feeds downlink channel state information (CSI). Each of the RI, PMI, and CQI is reported at its individual timing indicated by the eNB. For CSI feedback, the PMI is calculated based on the most recently reported RI, but the CQI is calculated assuming the most recently reported RI and PMI.

Improving cell area and information throughput is a key goal in communication systems. Coordinated Multi-Point (CoMP) transmission / reception is an important technology for achieving this purpose. CoMP operation is based on the fact that the UE may reliably receive (DL CoMP) signals from a set of multiple TPs and may reliably transmit (UL CoMP) signals to a set of RPs when the UE is in the cell edge region. Depends. DL CoMP schemes may include more complex schemes that require accurate and detailed channel information, such as co-transmissions from multiple TPs, from simple schemes of interference avoidance, such as coordinated scheduling. UL CoMP schemes may also include more complex schemes in which received signal characteristics at multiple RPs and generated interference are considered from simple schemes in which PUSCH scheduling is performed considering a single RP.

One embodiment of the present specification is to solve the above-described problems, and an object thereof is to provide an efficient CSI feedback method and apparatus in a CoMP system.

According to an embodiment of the present disclosure, a method of transmitting channel state information (CSI) of a terminal receiving a joint transmission (JT) from a first transmission point (TP) and a second TP may include: Receiving a first channel state information reference signal (CSI-RS) corresponding to the first TP, receiving a second CSI-RS corresponding to the second TP, the first CSI-RS and the first The method may include generating an aggregated CSI corresponding to the 2 CSI-RSs and transmitting the generated aggregated CSI. Generating an aggregated CSI corresponding to the first CSI-RS and the second CSI-RS may include generating the aggregated CSI using a transmission timing at which the aggregated CSI is transmitted.

A terminal that receives a joint transmission (JT) from a first transmission point (TP) and a second TP according to an embodiment of the present disclosure may include a first CSI-RS (corresponding to the first TP). A transceiver for receiving a Channel State Information Reference Signal and receiving a second CSI-RS corresponding to the second TP, and an aggregated CSI corresponding to the first CSI-RS and the second CSI-RS; It may include a control unit for generating channel state information (Channel State Information). The transceiver unit may transmit the generated sum CSI. The controller may generate the summed CSI using the transmission timing at which the summed CSI is transmitted.

According to an embodiment of the present disclosure, a method of receiving channel state information (CSI) of an upper device includes transmitting a first channel state information reference signal (CSI-RS), and transmitting the first CSI-RS from a terminal. Receiving an aggregated CSI comprising an aggregated CQI associated with an, obtaining a phase difference value corresponding to the received timing of the aggregated CSI, and scheduling using the aggregated CQI and the phase difference value; It may include.

An upper apparatus that receives channel state information (CSI) according to an embodiment of the present disclosure transmits a first channel state information reference signal (CSI-RS), and transmits a first CSI-RS to the first CSI-RS from a terminal. A transceiver for receiving an aggregated CSI including an associated aggregated CQI, and a controller for acquiring a phase difference value using the reception timing of the aggregated CSI and scheduling the aggregated CQI and the phase difference value. can do.

According to an embodiment of the present disclosure, an efficient CSI transmission / reception method and apparatus may be provided in a CoMP system.

1 shows a resource structure of LTE-A.
2 is a configuration diagram of resources in an LTE or LTE-A system.
3 is a structural diagram of a mobile communication system using CoMP.
4 is a diagram illustrating the location of CSI-RS resources of a terminal according to an embodiment of the present invention.
5 illustrates CSI feedback information and timing for two CSI-RS resources according to the first embodiment.
6 is a block diagram of a terminal (UE) according to an embodiment of the present invention.
7 is a block diagram of a base station (eNB) according to an embodiment of the present invention.
8 is a flowchart of a CSI feedback process according to an embodiment of the present invention.
9 is a flowchart illustrating a CSI reception process of a base station and other higher level devices according to an embodiment of the present invention.

In order to support DL CoMP in LTE-A system, new CSI feedback for various CoMP schemes should be introduced. Conventional CSI feedback schemes consider only one transmission point (TP) and one CSI-RS for channel measurement and CSI feedback reporting. Therefore, it is difficult to support CoMP schemes from a plurality of transmission points utilizing a plurality of CSI-RSs in the conventional CSI feedback scheme. For this reason, new CSI feedback (or CSI feedback for corresponding CSI-RS configurations) for multiple TPs is needed to support DL CoMP schemes. Feedback for CoMP schemes can be summarized as follows.

1. The plurality of CSI reports for the plurality of TPs may have at least some of the features indicated as 1-1 to 1-4 below.

1-1. The base station allocates a plurality of CSI-RS resources for CSI reporting to the terminal.

1-2. Each CSI-RS resource is used by the UE to measure the downlink channel from a specific TP.

1-2-1. According to an embodiment of the present invention, the case where one CSI-RS corresponds to multiple TPs is not excluded.

1-3. A set of a plurality of CSI-RS resources (or corresponding TPs) allocated to a terminal for CSI reporting is called a "CoMP measurement set".

1-4. The base station may allocate a mode and a transmission timing for each feedback corresponding to each CSI-RS to the terminal.

2. Additional feedback on dynamic transmission point selection and dynamic blanking (DS / DB) can be applied. In this case, the system may have at least some of the features indicated by 2-1 and 2-2 below.

2-1. Some TPs (eg, Macro Node B) may perform an operation (eg, zero power transfer) to turn off their data transmissions to help receive downlink data from UEs connected to other TPs.

2-2. The terminal may perform additional feedback reflecting an interference situation when specific TPs turn data transmission on and off (for example, zero power transmission).

3. Additional feedback on joint transmission (JT) may be applied. The joint transmission may have the features of at least some of the features indicated below in 3-1 and 3-2.

3-1. A plurality of TPs may simultaneously transmit data for one UE.

3-2. In order for a plurality of TPs to perform JT, the UE needs to perform additional feedback reflecting the JT situation.

3 is a structural diagram of a mobile communication system using CoMP. In the embodiment referring to FIG. 3, it is assumed that a cellular mobile communication system includes three cells. In addition, the term 'cell' as used herein refers to a data transmission area that a specific transmission point (TP) can serve, and each transmission point is the same cell identifier (cell-ID) as the macro base station in the macro area. It may be a remote radio head (RRH) having a). Alternatively, each transmission point may be a macro cell or a pico cell having a different cell identifier.

The central control unit 330 is a device capable of transmitting and receiving data with the terminals 301, 302, 311, and 321 and processing the transmitted and received data. Here, when each transmission point is an RRH having the same cell identifier as the macro base station, the macro base station may be referred to as a central control unit. In addition, when each transmission point is a macro cell or a pico cell having a different cell identifier, a device that integrates and manages each cell may be referred to as a central control device.

Referring to FIG. 3, the cellular mobile communication system transmits CoMP from at least one cell 300, 310, 320, terminals 301, 311, 321 receiving data from the closest cell and cells 300, 310, 320. It includes a terminal 302 receiving. The terminals 301, 311, and 321 receiving data from the nearest cell estimate the channel using the CSI-RS for the cell in which they are located, and transmit the related feedback to the central control apparatus 330. However, the terminal 302 receiving data from the three cells 300, 310, and 320 through the CoMP method should estimate the channels from all three cells 300, 310, and 320. Accordingly, the central control apparatus 330 allocates three CSI-RS resources corresponding to each cell 300, 310, and 320 to the terminal 302 for channel estimation performed by the terminal 302. A method of allocating CSI-RS resources to the terminal 302 by the central control apparatus 330 described above will be described with reference to FIG. 4.

4 is a diagram illustrating a location of a CSI-RS resource transmitted from a base station to a terminal according to an embodiment of the present invention.

Referring to FIG. 4, the central controller 330 estimates each channel from three cells 300, 310, and 320 by the terminal 302 receiving CoMP transmission, and estimates channels for control information and system information. Three CSI-RSs are allocated to each of the resources 401, 402, and 403 so that the CSI-RSs are transmitted using the corresponding resources. That is, the location of the resource to which the CSI-RS for channel estimation of the cell 300 is allocated is a reference number 401, and the location of the resource to which the CSI-RS for channel estimation of the cell 310 is allocated is a reference number (402). The location of the resource to which the CSI-RS for channel estimation of the cell 320 is allocated is 403. As described above, a set including a resource to which at least one CSI-RS transmitted for channel estimation of a CoMP terminal is allocated or a set including cells corresponding to the CSI-RS resource is referred to as a CoMP measurement set. It is called.

The central control unit 330 can also allocate additional resources used to measure interference to the terminal 302 to support the DS / DB technology. The amount of data per hour that the terminal 302 can receive is affected by the magnitude of the interference as well as the signal strength. Accordingly, the central control unit 330 may separately allocate an interference measurement resource (IMR) for measuring the interference by the terminal for accurate interference measurement of the terminal. The base station may assign one IMR to one terminal 302 to allow the terminal 302 to measure the amount of interference commonly applied to signal components for all CSI-RSs in the measurement set, or one terminal 302 A plurality of IMRs may be allocated to the terminal 302 so that the terminal 302 may measure interference for zero power transmission conditions and general transmission conditions of the interference TPs. Referring to FIG. 4, the terminal 302 measures signals from three cells 301, 311, and 321 using three allocated CSI-RS resources 401, 402, and 403. The terminal 302 may measure interference generated when receiving signals from three cells by using the resource 410 which is an allocated IMR. At this time, the base station or the central control unit 330 may control the signal transmission of the neighbor cells at the resource location 410 so that the interference to the terminal 302 with respect to the resource 410 can be well reflected.

The CSI report for the CoMP may be transmitted separately from the data information in the PUCCH, or with the data information in the PUSCH. Therefore, it is necessary to provide CSI reports for CoMP through PUSCH and PUCCH, respectively.

As described above, one basic feedback scheme for a plurality of CSI-RS resources includes a Per-CSI-RS-resource (per CSI-RS resource) for reporting channel status separately for the plurality of CSI-RS resources. ) Would be feedback. UEs measure respective CSI-RS resources for each of the plurality of TPs to generate and feed back CSI. The CSI is separate for some or all of the configured CSI-RS resources when performing per-CSI-RS-resource feedback. For example, if the CoMP measurement set for the UE is {CSI-RS-1, CSI-RS-2}, then the central control unit will convey the RRC information to the UE to generate CSI feedback for two separate feedback configurations. . An example thereof is provided below:

<Example 1>

_1.First feedback configuration of UE: (mode 1-1, N _pd = 10, N _{OFFSET, CQI} = 0, M _RI = 2, N _{OFFSET, RI} = -1, CSI-RS-1)

2. Second feedback configuration of UE: (mode 1-1, N _pd = 10, N _{OFFSET, CQI} = 2, M _RI = 2, N _{OFFSET, RI} = -1, CSI-RS-2)

In Example 1, mode 1-1 implies that the corresponding CSI feedback includes RI and wideband CQI / PMI. The reporting timing of the wideband CQI / PMI is subframes satisfying (10 × n _f + flo (n _s / 2) -N _{OFFSET, CQI} ) modN _pd = 0. Here, n _f is a system frame number, and n _s = {0, 1, ..., 19} is a slot index in a frame. N _{OFFSET, CQI} is the corresponding wideband CQI / PMI report offset in subframes, and N _pd is the wideband CQI / PMI period in subframes. The reporting interval of the RI report is an integer multiple (M _RI times) of the broadband CQI / PMI period N _pd (in subframe units). floor (x) is a function that returns the largest integer less than or equal to x. That is, report instances for _RI are subframes that satisfy (10 × n _f + flo (n _s / 2) -N _{OFFSET, CQI} ) mod (N _pd × M _RI ) = 0. Reporting Offset for RI N _{OFFSET, RI} takes values from the set {0, -1, ...,-(N _P -1)}. If the RI and the broadband CQI / PMI conflict, the broadband CQI / PMI is dropped.

5 illustrates CSI feedback information and timing for two CSI-RS resources according to the first embodiment. Each feedback for two different CSI-RSs is independently fed back according to the set timing.

If JT is considered, additional CSI for joint transmission from multiple TPs may be supported in addition to Per-CSI-RS-resource feedback. That is, if the CSI-RS resource allocated to the UE includes CSI-RS resources for a plurality of TPs, the UE feeds back individual CSIs for all configured CSI-RS resources, while providing phase differences between the TPs and And / or may additionally report CSI for a collection of CSI-RS resources, such as aggregated CQI for situations where JT is applied.

For example, a CoMP measurement set for a UE corresponding to TP-1 and TP-2 having N ₁ and N ₂ antenna ports, respectively, is {CSI-RS-1, CSI-RS-2} and corresponding two CSIs. Assume that the individual CSI determined for the -RSs has the characteristics indicated by 1 to 3 as follows:

1. The CQI determined for TP-1 is CQI-1 and the CQI determined for TP-2 is CQI-2

2. Rank is determined by r for both TP-1 and TP-2

3. Precoding matrices are P ₁ and P ₂ for TP-1 and TP-2, respectively

로 주어진다는 가정하에 생성될 수 있다. 여기서 θ는 M의 크기를 가지는 단위 복소수 집합

의 원소들 중 하나이다. θ는 JT에 참여하는 두 TP 사이의 위상 차이를 반영한다. 여기서 언급된 θ가 어느 TP를 기준으로 계산된 것인지가 문제될 수 있다. 예를 들어 기지국은 위상 θ가 어떠한 기준 지점으로부터 계산된 값인지를 지시하는 정보를 단말에게 제공할 수 있다. 예를 들어 기지국은 기준 지점에 상응하는 특정 CSI-RS에 대한 피드백 인덱스 또는 CSI-RS(또는 TP)의 인덱스를 단말에게 통보해 줄 수 있다. 이 경우 RRC 전송 또는 PDCCH 가 사용될 수도 있다. 변형 예에 따르면 기지국은 가장 작은 인덱스를 가지는 피드백 또는 CSI-RS(또는 TP)를 기준으로 다른 TP들의 위상 차이를 고려할 수도 있다. 상기 예시에서는 TP-1이 기준 지점으로 설정되어 θ는 TP-2의 TP-1에 대한 위상차를 나타내는 값이다. 이 경우 단말은 위상 차를 θ로 가정하고 프리코딩 매트릭스가

인 것으로 가정한 합산 CQI를 생성한다.Here, P ₁ and P ₂ have sizes of N ₁ × r and N ₂ × r, respectively, and each PMI is determined as a value corresponding to the precoding matrices P ₁ and P ₂ . If additional feedback for JT is considered, the UE should additionally generate and report the aggregated CQI indicating the channel state in the JT situation in which TP-1 and TP-2 simultaneously transmit data. For example, the sum of the CQIs for the JT situations of TP-1 and TP-2 is equal to r, the common rank value determined for the individual TPs, and of size (N ₁ + N ₂ ) × r for the JT situation. The precoding matrix

Can be generated under the assumption that Where θ is a unit complex set with M

Is one of the elements of. θ reflects the phase difference between the two TPs participating in JT. It may be questioned based on which TP the θ mentioned here is calculated based on. For example, the base station can provide the terminal with information indicating that the phase θ is a value calculated from which reference point. For example, the base station may inform the terminal of the feedback index or the index of the CSI-RS (or TP) for the specific CSI-RS corresponding to the reference point. In this case, RRC transmission or PDCCH may be used. According to a modification, the base station may consider the phase difference of other TPs based on feedback having the smallest index or CSI-RS (or TP). In the above example, TP-1 is set as a reference point, and θ is a value representing a phase difference with respect to TP-1 of TP-2. In this case, the terminal assumes that the phase difference is θ, and the precoding matrix is

Generate a summed CQI that is assumed to be.

Here, a method of determining θ, which is a value reflecting a phase difference between the TPs in a situation in which the UE generates a specific summed CQI and performs feedback, is considered. In the present embodiment, the terminal determines θ value for calculating the sum CQI in consideration of at least one of the following two factors.

1.Time at which feedback of the aggregated CQI is performed (timing)

2. Frequency domain corresponding to feedback of the sum CQI

Table 1 shows an example of the phase difference θ between the TPs determined according to the feedback timing of the wideband summation CQI, which is the CSI information for the entire downlink frequency band (wideband) used by the terminal.

Feedback timing 1 ^st report 2 ^nd report 3 ^rd report ... M ^th report (M + 1) ^th report ... Phase difference θ between TPs

...

...

중에서 (s₁+i mod M) 번째 원소로 가정하고 광대역 합산 CQI를 생성하는 것이다. 다시 말해, 본 예시에서 θ는 보고 타이밍에 따라 미리 결정된 주기적 방법으로 그 값이 결정된다. 여기서 θ의 시작 값 s₁은 0, 1 또는 기타 고정된 값일 수도 있고 RRC 방식으로 기지국이 단말에게 별도로 설정한 값이 될 수도 있다. M 또한 단말/기지국에게 알려진 고정된 값이거나, 기지국이 단말에게 RRC 또는 기타의 방법으로 통지한 값이 될 수 있다.In the method of determining θ shown in Table 1, when the UE reports the wideband sum CQI for the i th time, the UE sets a value of M possible values of θ.

It is assumed that the (s ₁ + i mod M) th element is to generate a broadband aggregated CQI. In other words, in the present example, θ is determined in a predetermined periodic method according to the reporting timing. Here, the starting value s ₁ of θ may be 0, 1, or other fixed value, or may be a value separately set by the base station to the terminal by the RRC method. M may also be a fixed value known to the terminal / base station or a value notified by the base station to the terminal by RRC or other means.

In the above-described embodiment, the criterion of the first report does not necessarily mean only the first report after the UE accesses the base station, and a randomly determined time point may be the time point of the first report. In the following other embodiments of the present specification, a randomly determined time point may be the time point of the first report.

중에서 f(s₁+i) 번째 원소로 가정하고 광대역 합산 CQI를 생성하는 것이다. 여기서 f(x)는 0 이상 M-1 미만의 정수를 출력하는 의사 랜덤 수열 또는 이에 상응하는 함수 값이다. 또는, f(x)는 0 이상 M-1 미만의 정수를 출력하는 다른 종류의 함수가 될 수도 있다. 표 1의 실시 예 또한 f(x) = (s₁+x mod M)인 경우의 예이다. 기지국과 단말은 f(x)의 계산을 위해 필요한 동일한 정보를 공유한다. 즉 해당 방법에서도 시작 값 s₁은 0, 1 또는 기타 고정된 값일 수도 있고 RRC 방식으로 기지국이 단말에게 별도로 설정한 값이 될 수도 있다. M 또한 단말/기지국에게 알려진 고정된 값이거나, 기지국이 단말에게 RRC 또는 기타의 방법으로 통지한 값이 될 수 있다.Another θ determination method according to a modified example includes a set of M values in which the UE can determine θ values.

It is assumed that the f (s ₁ + i) th element is to generate a broadband aggregated CQI. Where f (x) is a pseudo-random sequence that outputs an integer greater than 0 and less than M-1, or a corresponding function value. Alternatively, f (x) may be another kind of function that outputs an integer of 0 or more and less than M-1. The embodiment of Table 1 is also an example in the case of f (x) = (s ₁ + x mod M). The base station and the terminal share the same information necessary for the calculation of f (x). That is, even in the method, the start value s ₁ may be 0, 1, or other fixed value, or may be a value separately set by the base station to the terminal by the RRC method. M may also be a fixed value known to the terminal / base station or a value notified by the base station to the terminal by RRC or other means.

Table 2 divides the downlink frequency band used by the terminal into subbands, respectively.

An example of a method of determining a phase difference θ value between the TPs according to a corresponding subband index and feedback timing of a subband summation CQI in a situation of generating and reporting separate CSI information.

1 ^st report 2 ^nd report 3 ^rd report ... M ^th report (M + 1) ^th report ... subband 1

...

... subband 2

...

... subband 3

...

... ... ... ... ... ... ... ... ... subband L

...

...

중에서 (s _l +i mod M) 번째 원소로 가정하고 광대역 합산 CQI를 생성한다. 다시 말해, 본 예시에서 θ는 보고 타이밍 및 서브밴드 인덱스에 대하여 미리 결정된 주기적 방법으로 그 값이 결정된다. 여기서 각 서브밴드에 해당하는 θ의 시작 값 s₁, s₂, ..., s_L(표 2의 첫 번째 열)은 모두 0 또는 1로 고정된 값일 수도 있고 RRC 방식으로 기지국이 단말에게 별도로 설정한 값이 될 수도 있다. 변형 예에 따르면, 시작 값 s₁, s₂, ..., s_L은 다음 방법 1 또는 방법 2와 같은 서로 다른 값으로 설정 될 수도 있다:That is, according to Table 2, for the case in which the UE reports the sum CQI for the l- th subband as the i- th, the UE sets a set of M possible values of θ.

Create a wideband summed CQI, assuming the ( s _l + i mod M ) th element. In other words, in this example, θ is determined in a predetermined periodic manner with respect to the report timing and the subband index. Here, the starting values s ₁ , s ₂ , ..., s _L (the first column of Table 2) corresponding to each subband may be fixed values of 0 or 1, or the base station is separately provided to the terminal by the RRC method. It can also be a set value. According to a variant, the starting values s ₁ , s ₂ , ..., s _L may be set to different values such as the following method 1 or method 2:

Method 1: s _l = (l-1), l = 1,2, ..., L

Method 2:

According to a modification, the base station may deliver all of the starting values s ₁ , s ₂ ,..., S _L to the terminal using an RRC signal or other communication method.

중에서 f(s_l+i) 번째 원소로 가정하고 서브밴드 합산 CQI를 생성한다. 여기서 f(x)는 0 이상 M-1 미만의 값을 출력하는 의사 랜덤 수열 또는 이에 상응하는 함수 값이다. 또는, f(x)는 0 이상 M-1 미만의 정수를 출력하는 다른 종류의 함수가 될 수도 있다. 표 2의 실시 예 또한 f(x) = (s_l+x mod M)인 경우의 예이다. 기지국과 단말은 f(x)의 계산을 위해 필요한 동일한 정보를 공유한다. 이 경우에도 각 서브밴드의 θ의 시작 값 s₁, s₂, ..., s_L은 모두 0, 1 또는 기타 고정된 값일 수도 있고 RRC 방식으로 기지국이 단말에게 별도로 설정한 값이 될 수도 있다. M 또한 단말/기지국에게 알려진 고정된 값이거나, 기지국이 단말에게 RRC 또는 기타의 방법으로 통지한 값이 될 수 있다. L은 서브밴드 인덱스의 개수이다. 또 다른 변형 예에 따르면, 시작 값 s ₁, s ₂, ..., s _L 는 다음 방법 1 또는 방법 2에 따라 다른 값으로 설정 될 수도 있다:According to another modification, when the UE reports the sum CQI for the l-th subband as the i-th, a set of M possible values of corresponding θ values

The subband summed CQI is generated based on the f (s _l + i) th element. Where f (x) is a pseudo-random sequence that outputs a value between 0 and less than M-1, or a corresponding function value. Alternatively, f (x) may be another kind of function that outputs an integer of 0 or more and less than M-1. The embodiment of Table 2 is also an example in the case of f (x) = (s _l + x mod M). The base station and the terminal share the same information necessary for the calculation of f (x). Even in this case, the start values s ₁ , s ₂ , ..., s _L of each subband θ may be 0, 1 or other fixed values, or may be values set separately by the base station to the UE by the RRC method. . M may also be a fixed value known to the terminal / base station or a value notified by the base station to the terminal by RRC or other means. L is the number of subband indices. According to another variant, the starting values s ₁ , s ₂ , ..., s _L may be set to different values according to the following method 1 or method 2:

Method 1: s _l = (l-1), l = 1,2, ..., L

Method 2:

According to a modification, the base station may deliver all of the starting values s ₁ , s ₂ ,..., S _L to the terminal using an RRC signal or other communication method.

로 결정된다는 가정을 기반으로 하고 있다. 하지만 본 발명은 이에 한정하지 않는다. 즉, 두 개의 서로 다른 TP인 TP-1과 TP-2에 대하여 결정된 각 TP의 랭크 값이 각각 r ₁과 r₂로 서로 다르게 결정된 상황에서도 상기 TP 사이의 위상 차이를 반영하는 값인 θ를 결정하여 사용하는 방법을 고려할 수 있다. In the above-described embodiment, a precoding matrix used for JT is used when the rank values for each TP determined for two different TPs are equal to r .

Is based on the assumption that However, the present invention is not limited thereto. That is, even when the rank value of each TP determined for two different TPs, TP-1 and TP-2, is determined differently as r ₁ and r ₂ , respectively, θ is determined to reflect a phase difference between the TPs. You can consider how to use it.

Taking into account the situation that the rank value of each TP is determined differently as r ₁ and r ₂ , respectively, the CoMP measurement set for the UE corresponding to TP-1 and TP-2 having N ₁ and N ₂ antenna ports is set to {CSI Assume that the individual CSI determined with respect to the corresponding two CSI-RSs and RS-1, CSI-RS-2} has the characteristics indicated by the following 1-3.

1. The CQI determined for TP-1 is CQI-1 and the CQI determined for TP-2 is CQI-2

2. The rank is set differently with r ₁ for TP- ₁ and r ₂ for TP-2.

3. Precoding matrices are P ₁ and P ₂ for TP-1 and TP-2, respectively

Here, P ₁ and P ₂ have sizes of N ₁ × r ₁ and N ₂ × r ₂ , respectively, and each PMI is determined to a value corresponding to the precoding matrices P ₁ and P ₂ . If the additional CQI is considered as additional feedback for JT, then the combined CQI for the JT situation of TP-1 and TP-2 is r _JT = max (r ₁ , r, where the rank in the JT situation is greater than the rank for the individual TP. ₂ ) and can be generated under the assumption that the (N ₁ + N ₂ ) × r _JT sized precoding matrix for the JT situation is determined in the manner indicated by the following 1-2.

또는

로 가정If r ₁ is greater than r ₂ , the precoding matrix is

or

Assumption

또는

로 가정If r ₁ is less than r ₂ , the precoding matrix is

or

Assumption

Where B _{N × r} is one of the following matrices:

1.N matrix of size N × r

2. Specific N × r precoding matrix as defined in the LTE standard

In the assumption of the precoding matrix for the JT, the θ value represents a phase difference between TPs determined according to the feedback timing and / or subband index value by the method described in the above embodiments.

According to another embodiment, in a situation where the rank value of each TP is determined differently as r ₁ and r ₂ , respectively, the sum of the CQIs for the JT situations of TP-1 and TP-2 is the rank for the individual TPs. It can be generated on the assumption that r _JT = max (r ₁ , r ₂ ), which is the smallest of ranks, and that the precoding matrix of size (N ₁ + N ₂ ) × r _JT for the JT situation is determined by the following method. :

로 가정If r ₁ is greater than r ₂ , the precoding matrix is

Assumption

으로 가정If r ₁ is less than r ₂ , the precoding matrix is

Home

[P] _{N x r} is an _{N x r} matrix determined by selecting and selecting r columns from the M columns of the N x M size matrix P with respect to M values larger than r. The method of selecting and selecting the r columns is a specific selection method shared between the base station and the terminal. Here, in the assumption of the precoding matrix for the JT, the θ value represents a phase difference between TPs determined according to the feedback timing and / or subband index value by the method described in the embodiments.

6 is a block diagram of a terminal (UE) according to an embodiment of the present invention.

The UE includes a transceiver 1010, a channel estimator 1020, a feedback generator 1030, and a controller 1040. The transceiver 1010 transmits and receives control information, data, or reference signals with the eNB, and in particular, the transceiver 1010 receives the CSI-RS and also transmits the CSI feedback including the summed CQI for the JT between the TPs. Used to The channel estimator 1020 measures CSI-RS ports allocated to the UE. The feedback generator 1030 generates CSI feedback including the summed CQI in consideration of individual CSI feedback for the plurality of TPs and phase differences for JT between the TPs based on the measurements from the channel estimator 1020. do. All of the above operations are controlled by the control unit 1040. [ The controller 1040 controls the components of the UE to generate and transmit the aggregated CQI in any one or more of the embodiments mentioned herein.

7 is a block diagram of a base station (eNB) according to an embodiment of the present invention.

The eNB includes a controller 1110, a transceiver 1120, and a resource allocator 1130. The transceiver 1120 transmits and receives control information, data, or reference signals with the eNB. In particular, the transceiver 1120 transmits the CSI-RS and receives the CSI feedback including the summed CQI considering the phase difference of the JT between the TPs. The resource allocator 1130 allocates CSI-RS configurations to the UEs and schedules data resources to the UEs based on the CSI feedbacks from the UEs. All of the above operations are controlled by the controller 1110. The controller 1110 controls the components of the eNB to transmit the CSI-RS and receive the aggregated CQI in any one or more of the embodiments mentioned herein.

8 is a flowchart of a CSI feedback process according to an embodiment of the present invention.

Referring to FIG. 8, in step 1210, the feedback generator 1030 checks rank values of a plurality of TPs related to JT and determines a rank value to be used for JT. In this regard, it has been described in the above embodiments. Step 1210 may be omitted if the rank values of all TPs are to always be generated equal.

In operation 1220, the feedback generator 1030 determines a phase difference between the plurality of TPs by calculating a phase difference according to Table 1 or Table 2 and feedback timing and / or subband indexes related thereto. So that a precoding matrix corresponding to the phase difference is also determined.

In operation 1230, the feedback generator 1030 obtains a sum CQI under the assumption that the precoding matrix determined in operation 1220 is used.

In operation 1240, the feedback generator 1030 generates a CSI including at least some of the acquired RI, PMI, and CQI, and the transceiver 1010 transmits the corresponding CSI. Depending on the embodiment, some of the PMIs for RI, JT for JT may be omitted from the CSI. CSI containing a sum CQI is called a sum CSI. According to a modification, the aggregated CSI may further include information about the aggregated PMI and / or information about the aggregated RIs obtained according to any one or more of the above-described embodiments.

9 is a flowchart illustrating a CSI reception process of a base station and other higher level devices according to an embodiment of the present invention.

In step 910, the transceiver 1120 of the base station transmits the CSI-RS to the terminal. As described above, the resource location of the CSI-RS may be preset by the resource allocator 1130.

In step 920, the transceiver 1120 receives a CSI including the sum CQI from the terminal. The resource location of the sum CQI may be set in advance by the resource allocator 1130 as described above.

In operation 930, the controller 1110 extracts a phase value corresponding to the sum CQI. The controller 1110 extracts a phase value or a phase value indicator corresponding to the sum CQI by using the CSI transmission timing and / or the subband index in any one or more of the above-described embodiments.

In operation 940, the controller 1110 schedules the sum using the CQI and the corresponding phase value. For example, the controller 1110 may select a phase value (optimum phase value) corresponding to the best CQI among several summed CQIs including the summed CQIs previously received and schedule the corresponding terminal using the phase value. . Alternatively, the controller 1110 may first select / consider a phase value corresponding to an excellent CQI to determine a phase value to be applied to the corresponding terminal and schedule the corresponding terminal accordingly.

According to a modification, only a process of selecting a phase value may be performed by an upper apparatus of the base station, for example, the central control apparatus 330. In this case, the base station transmits the summed CQI and the corresponding phase value (which may be replaced with information necessary to obtain other phase values) among the summed CSI to the central control unit 330, and the central control unit uses the phase value. It may also inform the base station by selecting.

At this point, it will be appreciated that the combinations of blocks and flowchart illustrations in the process flow diagrams may be performed by computer program instructions. Since these computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, those instructions executed through the processor of the computer or other programmable data processing equipment may be described in flow chart block (s). It creates a means to perform the functions. These computer program instructions may also be stored in a computer usable or computer readable memory capable of directing a computer or other programmable data processing apparatus to implement the functionality in a particular manner so that the computer usable or computer readable memory The instructions stored in the block diagram (s) are also capable of producing manufacturing items containing instruction means for performing the functions described in the flowchart block (s). Computer program instructions may also be stored on a computer or other programmable data processing equipment so that a series of operating steps may be performed on a computer or other programmable data processing equipment to create a computer- It is also possible for the instructions to perform the processing equipment to provide steps for executing the functions described in the flowchart block (s).

In addition, each block may represent a portion of a module, segment, or code that includes one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative implementations, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may actually be executed substantially concurrently, or the blocks may sometimes be performed in reverse order according to the corresponding function.

Herein, the term &quot; part &quot; used in the present embodiment means a hardware component such as software or an FPGA or an ASIC, and 'part' performs certain roles. However, 'part' is not meant to be limited to software or hardware. &Quot; to &quot; may be configured to reside on an addressable storage medium and may be configured to play one or more processors. Thus, by way of example, 'parts' may refer to components such as software components, object-oriented software components, class components and task components, and processes, functions, , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and components may be further combined with a smaller number of components and components or further components and components. In addition, the components and components may be implemented to play back one or more CPUs in a device or a secure multimedia card.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

On the other hand, the present specification and the drawings have been described with respect to the preferred embodiments of the present invention, although specific terms are used, it is merely used in a general sense to easily explain the technical details of the present invention and help the understanding of the invention, It is not intended to limit the scope of the invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims (14)

In the method for transmitting channel state information (CSI) of a terminal that receives a joint transmission (JT) from a first transmission point (TP) and a second TP,
Receiving a first channel state information reference signal (CSI-RS) corresponding to the first TP;
Receiving a second CSI-RS corresponding to the second TP;
Generating an aggregated CSI corresponding to the first CSI-RS and the second CSI-RS; And
Transmitting the generated sum CSI;
Generating an aggregated CSI corresponding to the first CSI-RS and the second CSI-RS may include:
Generating the aggregate CSI using the transmission timing at which the aggregate CSI is transmitted. The method of claim 1,
Generating the summed CSI using the transmission timing at which the summed CSI is transmitted,
Generating the summed CSI using the transmission timing at which the summed CSI is transmitted and the subband indicator used by the terminal. The method of claim 1,
Generating the summed CSI using the transmission timing at which the summed CSI is transmitted,
Obtaining a phase difference between the first TP and the second TP using a transmission timing at which the aggregated CSI is transmitted;
Generating a summed CQI using the obtained phase difference and the received first CSI-RS and the second CSI-RS; And
Generating a summed CSI comprising the summed CQI. The method of claim 3,
The generating of the summation CSI using the transmission timing at which the summation CSI is transmitted may include a summation precoding matirix identifier using the acquired phase difference and the received first and second CSI-RSs. )
Generating a summed CSI including the summed CQI comprises generating a summed CSI comprising the summed CQI and the summed PMI. A terminal for receiving a joint transmission (JT;) from a first transmission point (TP) and a second TP,
A transceiver for receiving a first channel state information reference signal (CSI-RS) corresponding to the first TP and a second CSI-RS corresponding to the second TP; And
And a controller configured to generate aggregated CSI (Channel State Information) corresponding to the first CSI-RS and the second CSI-RS.
The transceiver unit transmits the generated sum CSI,
The control unit is characterized in that for generating the sum CSI by using the transmission timing that the sum CSI is transmitted. The method of claim 5,
And the control unit generates the aggregate CSI by using a transmission timing at which the aggregate CSI is transmitted and a subband indicator used by the terminal. The method of claim 5,
The control unit obtains a phase difference between the first TP and the second TP using a transmission timing at which the aggregated CSI is transmitted, and obtains the obtained phase difference and the received first CSI-RS and the second CSI. Generating a summed CQI using the RS and generating a summed CSI including the summed CQI. The method of claim 7, wherein
The controller generates a summation precoding matirix identifier (PMI) using the obtained phase difference and the received first CSI-RS and the second CSI-RS, and generates a summation CSI including the summation CQI. The step of generating a summing CSI including the summing CQI and the summing PMI. In the channel state information (CSI) receiving method of a higher level device,
Transmitting a first Channel State Information Reference Signal (CSI-RS);
Receiving an aggregated CSI including an aggregated CQI associated with the first CSI-RS from a terminal;
Obtaining a phase difference value corresponding to the reception timing of the sum CSI; And
And scheduling using the summed CQI and the phase difference value. 10. The method of claim 9,
Scheduling using the summed CQI and the corresponding phase difference value comprises preferentially selecting and scheduling a phase difference value corresponding to a good summed CQI. 10. The method of claim 9,
The scheduling using the summed CQI and the corresponding phase difference value includes selecting and scheduling a phase difference value corresponding to the best summed CQI. In a higher level device receiving channel state information (CSI),
A transceiver for transmitting a first channel state information reference signal (CSI-RS) and receiving an aggregated CSI including an aggregated CQI associated with the first CSI-RS from a terminal; And
And a controller configured to obtain a phase difference value corresponding to the received timing of the sum CSI and to schedule the sum using the sum CQI and the phase difference value. The method of claim 12,
And the control unit preferentially selects and schedules a phase difference value corresponding to a good sum CQI. The method of claim 12,
The controller selects and schedules a phase difference value corresponding to the best sum CQI.

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