WO2011085679A1

WO2011085679A1 - Method and system for indicating additional pre-coding matrix index

Info

Publication number: WO2011085679A1
Application number: PCT/CN2011/070201
Authority: WO
Inventors: 李儒岳; 徐俊; 陈艺戬; 郁光辉; 戴博; 张峻峰
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-01-12
Filing date: 2011-01-12
Publication date: 2011-07-21
Also published as: CN101771505B; CN101771505A

Abstract

A method and system for indicating an additional pre-coding matrix index are provided in this invention. The method includes the following steps: a User Equipment (UE) determines the type of an additional pre-coding matrix index, and carries the indication information for indicating the type of the additional pre-coding matrix index in the uplink control information, and sends it to the Enhanced Node B (eNB); or, the eNB determines the type of the additional pre-coding matrix index, and carries the indication information for indicating the type of the additional pre-coding matrix index in the downlink control information or the high layer configuration signaling, and sends it to the UE. Wherein, the additional pre-coding matrix index is the Best-Companion Index (BCI) or the Worst-Companion Index (WCI). With this invention, not only the performance of the multi-user MIMO or Coordinated Multiple Point transmission (CoMP) is improved, but also the eNode B can realize the multi-user MIMO or Coordinated Multiple Point transmission (CoMP) more easily.

Description

Method and system for indicating additional precoding matrix index

Technical field

The present invention relates to the field of communications, and in particular, to an additional method and system for indicating a precoding matrix index.

Background technique

In the Long Term Evolution (LTE) system, the information reflecting the state of the downlink physical channel (CSI: Channel State Information) has three forms: CQI: Channels quality indication, Precoding matrix. Indication (PMI: Pre-coding Matrix Indicator) and rank indication (RI: Rank Indicator).

CQI is an indicator to measure the quality of downlink channels. In the 36-213 protocol, CQI is represented by integer values from 0 to 15, which respectively represent different CQI levels. Different CQIs correspond to their respective modulation modes and coding rate (MCS), which are divided into 16 cases and can be used. 4 bits of information to represent.

PMI refers to user equipment (UE: User only) in closed-loop spatial multiplexing.

Equipment) Tells the base station (eNB: eNode B) what precoding matrix should be used to precode the Physical Downlink Shared Channel (PDSCH) channel addressed to the UE based on the measured channel quality. The feedback granularity of the PMI can be that the entire bandwidth is fed back to a PMI, or the PMI can be fed back according to the subband.

The RI is used to describe the number of spatially independent channels, corresponding to the rank of the channel response matrix. In the open-loop spatial multiplexing and closed-loop spatial multiplexing mode, the UE needs to feed back RI information, and other modes do not need to feed back RI information. The rank of the channel matrix corresponds to the number of layers.

The rank of the matrix may have two determination methods, one is the rank of the channel determined based on the maximum capacity criterion of the single user (SU), and is mainly used for single-user multiple input multiple output (MIMO: Multiple Input Multiple Output); The size of the RI is determined based on the relative value of the feature values. In fact, there are other ways to determine the rank, depending on the specific usage scenario.

In the LTE system, the feedback of the CQI, the PMI, or the RI may be periodic feedback or non-periodic feedback. The specific feedback is shown in Table 2: Table 2 Uplink physical channels corresponding to periodic feedback and aperiodic feedback

The CQI, the PMI, or the RI of the periodic feedback on the physical uplink control channel (PUCCH: Physical Uplink Control Channel) is in the format 2/2a. /2b (PUCCH format2/2a/2b) transmission, if the UE needs to transmit data, the CQI, PMI or RI is transmitted in the Physical Uplink Shared Channel (PUSCH); For the non-periodic feedback CQI, PMI Or RI, only transmitted on the PUSCH.

In the LTE system, the payload CQI, PMI, or RI payload size transmitted on the PUCCH channel is different in different transmission modes, but the maximum payload is 11 bits. For periodic feedback, first use the Reed-Muller (20, A) to encode the M (M<=11) bit CQI, PMI or RI, and then modulate the encoded bits to PUCCH format 2/2a/2b. The form of transmission.

The LTE-A (Long Term Evolution Advanced), which is the evolution standard of LTE, needs to support a larger system bandwidth (up to 100 MHz) and needs to improve the average frequency efficiency and the frequency efficiency of the cell edge users. To this end, the LTE-A system introduces many new technologies: (1) Downstream high-order MIMO, the LTE system supports up to 4 antenna transmissions in the downlink, and the introduction of high-order MIMO enables the LTE-A system to support up to 8 antennas in the downlink. Then, the dimension of the channel state matrix is increased; (2) CoMP (Coordinated multiple point transmission), which is a cooperative transmission using multiple cell transmit antennas, then the UE may need to feed back channel state information of multiple cells. .

In LTE-A, several companies have proposed to improve the performance of single-cell multi-user MIMO and multi-cell MIMO (CoMP) by enhancing the feedback to the UE. Compared to Release 8 (LTE standard), UE feedback requires an additional report of the precoding matrix index (ie, additional PMI). Additional PMIs may take two forms, one is BCI (best-companion PMI) and the other is WCI (wors-companion PMI). The BCI is preferably accompanied by a precoding matrix index, or preferably paired with a precoding matrix index, which refers to information on how to reduce intra-cell or inter-cell interference to the best. When the eNB implements multi-user MIMO UE pairing on the same time and frequency resources, based on this additional information, the UE can observe lower intra-cell interference.

WCI (wors-companion PMI) is the worst companion precoding matrix index, or the worst paired precoding matrix index, which refers to how to generate intra-cell or inter-cell interference to the maximum information. That is, WCI indicates that it should be avoided. The worst case.

The following is an example to illustrate BCI and WCI, but does not exclude other forms. It is assumed that the eNB has =8 transmit antennas, and the UE also has N _R =8 antennas. At this time, the size of the channel matrix H _k measured by the resource UE at a certain time is 8*8, if the channel correlation matrix is matched! ^! ^ The disjunction of the language can be obtained as follows:

Here, H _k is the channel matrix of the Kth UE, its size is ^, Ν _τ is the number of eNB transmit antennas, N _R is! ^The number of receiving antennas, _Vl ... ν _Ντ is! The eigenvector of I^H _k , v _{; the} size is N _r xl, i = l, -, N _T , | | ² , ..., | | ² is the eigenvalue of the channel correlation matrix 3⁄4H _k , where N _r = 8, N _R = 8. In addition, the _V1 ... ^ constitutes a right-hand matrix of the SVD decomposition of the channel matrix H _k .

As shown in Fig. 1, if | _σι | ² , |σ ₂ | ^{2 is} significantly larger than |σ ₃ | ² , |σ ₄ | ² and | _σι | ² , |σ ₂ | ² , |σ ₃ | ² , |σ ₄ | ^{2 is} significantly larger than |σ ₅ | ² , |σ ₆ | ² , |σ ₇ | ² , |σ ₈ | ² (small), then the first and second eigenvector spaces are used to transmit signals, which can be called The signal ΡΜΙ; the third and fourth eigenvector spaces constitute the worst pairing ΡΜΙ; the fifth to eight eigenvector spaces constitute the best pairing ΡΜΙ. It should be noted that the division and identification of the signals PMI, BCI and WCI are not limited to the described embodiments, in general they are determined by the UE according to specific criteria.

At the transmitting end (eNB) using multiple antennas, we can take spatial multiplexing to improve the transmission rate, that is, transmit different data at different antenna positions on the same time-frequency resource at the transmitting end, at the receiving end (UE). Also using multiple antennas, we can put all antennas in the case of a single user Resources are allocated to the same user. This transmission form is called SU-MIMO (single-user MIMO). In addition, we can allocate resources of different antenna spaces to different users in the case of multiple users. This transmission form is called MU-MIMO. User MIMO).

In the LTE-A system, multi-user MIMO and multi-point cooperative transmission CoMP are required for downlink. When there are few UEs, if the report of adding additional PMI is BCI report, it will be difficult to achieve pairing, so the report of adding additional PMI should be WCI report; when there are more UEs, it is easier to achieve pairing and add extra If the PMI report is a BCI report, MU-MIMO or CoMP can achieve better performance. In addition, at high signal-to-noise ratios, interference plays a decisive role because of the small noise. If additional PMI reports are added, BCI reports can better suppress interference and improve MU-MIMO or CoMP. Performance, so the report of adding additional PMI should be BCI report; at low SNR, because the noise is very large, the impact of interference size is not large. If the report of adding additional PMI is WCI report, although it can be increased a little Interference, but can better achieve pairing between users. In addition, for low rank cases, it is better to add additional PMI reports if WCI reports; for high rank cases, adding additional PMI reports is better if BCI reports.

Based on the above, the report of adding additional PMI may be either BCI or WCI, and BCI and WCI have different usage scenarios. Although the prior art proposes that the added feedback may be the feedback of the BCI or the WCI, but which entity chooses, how to indicate the selected BCI or WCI is an urgent problem to be solved.

Summary of the invention

It is an object of the present invention to provide an additional method and system for indicating a precoding matrix index to solve the problem of indicating the type of precoding matrix index selected.

In order to solve the above technical problem, the present invention provides an indication method for an additional precoding matrix index, including:

The user equipment (UE) determines an additional precoding matrix index type, and carries indication information indicating an additional precoding matrix index type in the uplink control information, and sends the uplink control information to the base station (eNB); or The eNB determines an additional precoding matrix index type, and carries indication information indicating an additional precoding matrix index type in the downlink control information or the high layer configuration signaling, and sends the downlink control information or the high layer configuration signaling to the UE.

The additional precoding matrix index is a best paired precoding matrix index (BCI) or a worst paired precoding matrix index (WCI).

Preferably, the above method may also have the following features:

The additional precoding matrix index is an index of a quantization matrix, or an index of one or more quantization vectors.

Preferably, the above method may also have the following features:

The indication information is a distinguishing indication information of a BCI or a WCI.

Preferably, the above method may also have the following features:

The uplink control information is channel state information including an additional precoding matrix index.

Preferably, the above method may also have the following features:

The channel state information including the additional precoding matrix index includes:

One or more Precoding Matrix Indicators (PMI), one BCI or WCI discrimination indication information, one or more additional precoding matrix indices, and one or more Channel Quality Indicator Information (CQI).

Preferably, the above method may also have the following features:

The high layer configuration signaling is Radio Resource Control (RRC) signaling.

Preferably, after the step of sending the downlink control information or the high layer configuration signaling to the UE, the method further includes:

The UE learns an additional precoding matrix index type according to the received indication information, and sends channel state information including an additional precoding matrix index to the eNB.

Preferably, the above method may also have the following features:

One or more PMIs, one or more additional precoding matrix indexes, and one or more

CQI. In order to solve the above technical problem, the present invention further provides an indication system for an additional precoding matrix index, including a UE and an eNB.

The UE is configured to: determine an additional precoding matrix index type, and carry indication information indicating an additional precoding matrix index type in the uplink control information, and send the uplink control information to the eNB;

The eNB is configured to learn an additional precoding matrix index type according to the received indication information, where the additional precoding matrix index type is BCI or WCI.

In order to solve the above technical problem, the present invention further provides an indication system for an additional precoding matrix index, including a UE and an eNB.

The eNB is configured to: determine an additional precoding matrix index type, and carry indication information indicating an additional precoding matrix index type in the downlink control information or the high layer configuration signaling, where the downlink control information or the high layer configuration information is Send to the UE;

The UE is configured to learn an additional precoding matrix index type according to the received indication information, where the additional precoding matrix index type is BCI or WCI.

The present invention is suitable for selecting BCI or WCI for feedback in different usage scenarios. By using the present invention, not only the performance of multi-user MIMO or multi-point coordinated transmission CoMP is improved, but also the base station is more likely to implement multi-user MIMO or multi-point cooperation. Transfer CoMP. BRIEF abstract

Figure 1 is a feature space decomposition diagram of an 8-bit 8-received channel matrix;

2 is a flowchart of an indication method of an additional precoding matrix index according to Embodiment 1 of the present invention; FIG. 3 is a feature space decomposition diagram of a 4-band 4 channel matrix;

4 is an uplink control information format including BCI or WCI distinguishing indication information, BCI or WCI;

Figure 5 - The uplink control information format including BCI or WCI. Preferred embodiment of the invention

In the present invention, the precoding matrix index type is indicated in two ways:

method one

The UE determines an additional precoding matrix index type, and carries indication information indicating an additional precoding matrix index type in the uplink control information (UCI), and transmits the indication information to the base station.

Among them, the additional precoding matrix index is BCI or WCI.

The indication information is BCI or WCI distinguishing indication information, and is used to indicate whether the current additional precoding matrix index refers to BCI or WCL.

The additional precoding matrix index is an index of one quantization matrix or an index of one or more quantization vectors.

The UE adds indication information in an uplink control information format, where the uplink control information is channel state information including an additional precoding matrix index.

One or more PMIs, one BCI or WCI distinguishing indication information, one or more additional precoding matrix indexes, and one or more CQIs. The additional precoding matrix index can only be one of the BCI or the WCI, which is consistent with the indication of the BCI or WCI distinguishing indication information carried in the channel state information.

Way two

The base station determines an additional precoding matrix index type, and carries indication information indicating an additional precoding matrix index type in the downlink control information or the high layer configuration signaling, and sends the indication information to the UE.

The additional precoding matrix index is BCI or WCI.

The additional precoding matrix index BCI or WCI is an index of a quantization matrix or an index of one or more quantization vectors.

The base station adds the indication information to the downlink control information, or carries the indication information in the downlink high-level configuration signaling, where the “high-level” usually refers to a layer above the physical layer, and the high-level configuration signaling may be It is Radio Resource Control (RRC) signaling.

The UE learns an additional precoding matrix index type according to the received indication information, and sends channel state information including an additional precoding matrix index to the base station.

(CQI). The additional precoding matrix index may only be one of BCI or WCI, which depends on the indication of the indication information in the downlink control information or the high layer configuration signaling.

The present invention is applicable to a corresponding single-user MIMO (SU-MIMO) system or a multi-user MIMO (MU-MIMO) system or a multi-point cooperative CoMP system.

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Embodiment 1

As shown in FIG. 2, the UE determines an additional precoding matrix index type, which specifically includes the following steps:

S201. The sending end (ie, the base station, the eNB) sends a pilot to the UE, where the UE is used to test the downlink channel status.

S203. The UE estimates a downlink channel according to the received pilot information.

S205. The UE determines an additional precoding matrix index type, that is, determining whether the uplink channel state control information includes a BCI or a WCI.

S207. The UE feeds back uplink channel state control information to the sending end.

The channel state control information fed back by the UE includes: one or more precoding matrix indicators (PMIs), one or more additional precoding matrix indexes, one indication information for distinguishing BCI or WCI, one or more channel qualities. Indication information (CQI);

The sending end knows whether the additional precoding matrix index is BCI or WCI according to the indication information of the BCI or WCI that is fed back by the UE;

S209. The sending end performs scheduling according to channel state information fed back by the UE, and configures channel state information in actual transmission. For example, if the eNB has = 4 transmit antennas, the UE also has N _R = 4 antennas. At this time, on a certain time frequency resource, the size of the channel matrix H _k measured by the UE is 4*4, if the channel is related. The matrix H _k is decomposed and can be obtained as follows:

Η3⁄4 = |σ" ² v _lV f + |σ" ² v ₂ v + |σ" ² v ₃ v + |σ ₄ | ² v ₄ v As shown in Fig. 3, suppose | _σι | ² » |σ ₂ | ² > |σ ₃ | ² , |σ ₄ | ² , |σ ₃ | ² , |σ ₄ | ^{2 is} small, then the first eigenvector space is used to transmit signals, which can be called signal ΡΜΙ; second eigenvector The space constitutes the worst pairing; the third and fourth feature vector spaces constitute the best pairing. It should be noted that the division and identification of the signal ΡΜΙ, BCI and WCI are not limited to the described embodiments, in general they are determined by the UE according to specific criteria.

Here, as shown in FIG. 4, one form of the uplink channel state information includes: a coding matrix indicator (PMI), that is, a quantization vector index; an additional precoding matrix index; that is, two quantizations of v ₃ , Vector index, or v ₃ , a quantization matrix index constituting a matrix; a BCI or WCI distinguishing indication information, when the value is 0, indicating that the additionally added precoding matrix index is a BCI; one or more channel quality indication information CQI;

As shown in Figure 4, the uplink channel status information is another form of obituary:

Encoding matrix indicator (PMI), that is, a quantization vector index; an additional precoding matrix index; that is, a quantization vector index of v ₂ ; a BCI or WCI distinguishing indication information, when the value is 1, indicating an additional pre-increment The coding matrix index is WCI; one or more channel quality indication information CQI.

Wherein, Figure 4†N, M, and K are positive integers greater than or equal to 1.

The UE transmits the above-mentioned channel state information report to the eNB, and the eNB performs processing such as single-user MIMO or multi-user MIMO or CoMP scheduling according to the report. Embodiment 2: determining, by the eNB, an additional precoding matrix index type, including: the eNB determining an additional precoding matrix index type, and carrying, in the downlink control information, indication information indicating an additional precoding matrix index type, and sending the indication information to the UE; The UE learns an additional precoding matrix index type according to the received indication information, and sends channel state information including an additional precoding matrix index to the base station.

The channel state information includes: one or more precoding matrix indicators (PMIs), one or more additional precoding matrix indexes, and one or more channel quality indication information (CQIs). The additional precoding matrix index may only be one of BCI or WCI, which depends on the indication information in the downlink control information. For example, if the eNB has = 4 transmit antennas, the UE also has N _R = 4 antennas. At this time, on a certain time frequency resource, the size of the channel matrix H _k measured by the UE is 4*4, if the channel is related. The matrix H _k is decomposed and can be obtained as follows:

Η3⁄4 = |σ" ² v _lV f + |σ" ² v ₂ v + |σ" ² v ₃ v +

v ₄ v As shown in Fig. 3, suppose | _σι | ² »|σ ₂ | ² >|σ ₃ | ² , |σ ₄ | ² , |σ ₃ | ² , |σ ₄ | ^{2 is} small, then the first The eigenvector space is used to transmit signals, which can be called signal ΡΜΙ; the second eigenvector space constitutes the worst pairing ΡΜΙ; the third and fourth eigenvector spaces constitute the best pairing ΡΜΙ. It should be noted that the division and identification of the signal ΡΜΙ, BCI and WCI are not limited to the described embodiments, in general they are determined by the UE according to specific criteria. Here, as shown in FIG. 5, the distinguishing indication information of the BCI or the WCI in the downlink control information is 0, and one form of the uplink channel state information includes: a coding matrix indicator (PMI), that is, a quantization vector index; additional pre-coding matrix index; i.e., v _3, the two vector quantization index, or v _3, constituting the matrix quantization matrix index; one or more of the CQI channel quality indication information; 5, if the downlink control information The distinguishing indication information of BCI or WCI is 1, and the uplink ^ Channel state information report of another form Gen comprising: coding matrix indicator (PMI), i.e., a vector quantization index; additional pre-coding matrix index; i.e., v a vector quantization index _2; one or more channel quality Indicates the information CQI.

Wherein, in Fig. 5, N, M, and K are positive integers greater than or equal to 1.

The UE transmits the above-mentioned channel state information report to the eNB, and the eNB performs processing such as single-user MIMO or multi-user MIMO or CoMP scheduling according to the report.

Embodiment 3: The eNB determines an additional precoding matrix index type, and performs semi-static configuration on the UE by using configuration signaling, including: the eNB determines an additional precoding matrix index type, and carries it in high layer configuration signaling (RRC signaling). And sending, to the UE, indication information indicating an additional precoding matrix index type; the UE, according to the received indication information, learns an additional precoding matrix index type, and sends channel state information including an additional precoding matrix index to the base station. .

The channel state information includes: one or more precoding matrix indicators (PMIs), one or more additional precoding matrix indexes, and one or more channel quality indication information (CQIs). The additional added precoding matrix index can only be one of BCI or WCI, which depends on the indication information in the high layer configuration signaling. For example, if the eNB has = 4 transmit antennas, the UE also has N _R = 4 antennas. At this time, on a certain time frequency resource, the size of the channel matrix H _k measured by the UE is 4*4, if the channel is related. The matrix H _k is decomposed and can be obtained as follows:

Η3⁄4 = |σ" ² v _lV f + |σ" ² v ₂ v + |σ" ² v ₃ v +

v ₄ v As shown in Fig. 3, assume that | _σι | ² » |σ ₂ | ² > |σ ₃ | ² , |σ ₄ | ² , |σ ₃ | ² , |σ ₄ | ^{2 is} small, then the first The eigenvector space is used to transmit signals, which can be called signal ΡΜΙ; the second eigenvector space constitutes the worst pairing ΡΜΙ; the third and fourth eigenvector spaces constitute the best pairing ΡΜΙ. It should be noted that the division and identification of the signal ΡΜΙ, BCI and WCI are not limited to the embodiments described, in short, they are The criteria are determined. Here, if the indication information added in the downlink configuration signaling is 0, as shown in FIG. 5, one form of the uplink channel state information is:

Coding matrix indicator (the PMI), i.e., a vector quantization index; additional pre-coding matrix index; i.e., v _3, the two vector quantization index, or v _3, constituting the matrix quantization matrix index; one or more channel quality indicator Information CQI;

If the indication information added in the downlink configuration signaling is 1, as shown in FIG. 5, another form of the uplink channel status information is:

Coding matrix indicator (PMI), i.e., a vector quantization index; additional pre-coding matrix index; i.e., v a vector quantization index _2; one or more channel quality indicator CQI.

The indication system of the additional precoding matrix index of the embodiment of the present invention includes a UE and a base station, where the UE is configured to: determine an additional precoding matrix index type, and carry an index for indicating an additional precoding matrix in the uplink control information. The indication information of the type is sent to the base station; the base station is configured to learn an additional precoding matrix index type according to the received indication information. An indication system of an additional precoding matrix index includes a UE and a base station, where the base station is configured to: determine an additional precoding matrix index type, which is carried in the downlink control information or the high layer configuration signaling. The indication information indicating the additional precoding matrix index type is sent to the UE; the UE is configured to learn an additional precoding matrix index type according to the received indication information. In the foregoing embodiment, when the distinguishing indication information of the BCI or the WCI is 0, it indicates that the additionally added precoding matrix index is BCI; when the value is 1, it indicates that the additionally added precoding matrix index is WCI. Of course, when the BCI or WCI distinguishing indication information takes a value of 1, it indicates that the additionally added precoding matrix index is BCI; when the value is 0, it indicates that the additionally added precoding matrix index is WCI. The invention may, of course, be embodied in various other forms and modifications without departing from the spirit and scope of the invention.

Industrial applicability

Compared with the prior art, the present invention not only improves the performance of multi-user MIMO or multi-point coordinated transmission CoMP, but also makes it easier for a base station to implement multi-user MIMO or multi-point cooperative transmission CoMP.

Claims

Claim

1. An indication method for an additional precoding matrix index, comprising:

The user equipment (UE) determines the type of the additional precoding matrix index, and carries the indication information indicating the type of the additional precoding matrix index in the uplink control information, and sends the uplink control information to the base station (eNB); or ,

The eNB determines the type of the additional precoding matrix index, and carries the indication information indicating the type of the additional precoding matrix index in the downlink control information or the high layer configuration signaling, and sends the downlink control information or the high layer configuration signaling to UE;

2. The method of claim 1 wherein

The additional precoding matrix index is an index of a quantization matrix or an index of one or more quantization vectors.

3. The method of claim 1, wherein

The indication information for indicating the type of the additional precoding matrix index is the discrimination indication information of the BCI or the WCI.

4. The method of claim 3, wherein

5. The method of claim 4, wherein

6. The method of claim 1, wherein

The method of claim 1, after the step of transmitting the downlink control information or the high layer configuration signaling to the UE, the method further includes:

8. The method according to claim 7, wherein the channel state information including the additional precoding matrix index comprises:

CQI.

9. An indication system for an additional precoding matrix index, comprising a UE and an eNB, characterized in that

The UE is configured to: determine an additional type of the precoding matrix index, and send the uplink control information to the eNB after the indication information indicating the type of the additional precoding matrix index is carried in the uplink control information;

The eNB is configured to learn an additional type of precoding matrix index according to the received indication information;

The additional precoding matrix index is a best paired precoding matrix index BCI or a worst paired precoding matrix index WCI.

10. An indication system for an additional precoding matrix index, comprising a UE and an eNB, characterized in that

The eNB is configured to: determine an type of the additional precoding matrix index, and after the downlink control information or the high layer configuration signaling carries the indication information indicating the type of the additional precoding matrix index, the downlink control information or The high layer configuration signaling is sent to the UE;

The UE is configured to learn the type of the additional precoding matrix index according to the received indication information;