WO2012152145A1

WO2012152145A1 - Method and device for feeding back channel information

Info

Publication number: WO2012152145A1
Application number: PCT/CN2012/073109
Authority: WO
Inventors: 姜静; 郁光辉; 孙云锋
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-05-12
Filing date: 2012-03-27
Publication date: 2012-11-15
Also published as: CN102780544A

Abstract

Disclosed in the present invention is a method for feeding back channel information, the method comprises: quantifying the precoding matrix index (PMI) of a main cell channel according to a fixed bit; according to the relative channel quality of each cooperative cell, determining a PMI bit of each cooperative cell channel and quantifying the PMI of each cooperative cell channel; feeding back the quantified PMI of the main cell channel and of each cooperative cell channel to a main-cell base station; wherein, the relative channel quality indicates the quantization difference between the channel quality of the cooperative cell and the channel quality of the main cell. The invention also discloses a device for feeding back the channel information, which realizes the adaptive quantization of the channel information of the cooperative cell, thereby, the feedback quantity of the channel information can be controlled based on the actual needs. While the channel information feedback of multiple cells is achieved in a coordinated multi-point transmission and reception (CoMP) system, the feedback quantity and the system overhead can be reduced, and the resource can be saved.

Description

Channel information feedback method and device

The present invention relates to a CoMP (Coordinated Multi-Point transmission/reception) technology, and in particular, to a channel information feedback method and apparatus. Background technique

At present, the channel information feedback method of the single cell is: the user equipment (UE, User Equipment) quantizes the channel information of the cell into a channel quality indicator (CQI, channel quality index) and a precoding matrix indication (PMI, according to fixed bits). Precoding Matrix Index ), and feedback to the base station.

CoMP technology can effectively suppress interference between UEs through inter-cell cooperation processing, which can effectively improve the frequency utilization of the system. The primary cell in the CoMP system and the coordinated cell of the primary cell provide services to the UE. When the number of antennas increases and the cooperation of the multiple cells cooperates, the UE needs to simultaneously feed back the channel information of the primary cell and the coordinated cell. Channel information, as such, the amount of feedback is much higher than in the case of a single cell. Based on the above reasons, applying the existing single-cell channel information feedback method to the CoMP system will inevitably lead to a large amount of channel information feedback, which will cause a large system overhead and affect the system running speed and resource waste. Therefore, it is necessary to propose a suitable CoMP system. And a method capable of effectively feeding back channel information of multiple cells to a UE. Summary of the invention

In view of this, the main object of the present invention is to provide a channel information feedback method and apparatus, which can effectively feedback channel information of multiple cells of a CoMP system to a UE and reduce feedback amount.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

The present invention provides a channel information feedback method, and the method includes: Obtaining the PMI of the primary cell channel according to the fixed bit quantization; determining the PMI bit of each coordinated cell channel according to the relative channel quality of each coordinated cell and quantizing the PMI of each coordinated cell channel;

The PMI of the primary cell channel and the PMI of each coordinated cell channel are fed back to the primary cell base station;

The relative channel quality indicates a quantized difference between a channel quality of the coordinated cell and a channel quality of the primary cell.

In the above solution, the PMI of the primary cell channel is quantized according to fixed bits, and the PMI of the primary cell channel is obtained according to a fixed 4-bit quantization.

In the above solution, the method further includes: determining a relative channel quality level of each coordinated cell according to an SNR difference or a CQI difference between the primary cell and each coordinated cell.

In the foregoing solution, the determining, according to the SNR difference between the primary cell and each coordinated cell, the relative channel quality of each coordinated cell, according to: a SNR difference between the primary cell and each coordinated cell, and a preset SNR. The difference threshold is used to determine a relative channel quality level of each coordinated cell; or, according to a SNR difference between the primary cell and each coordinated cell, a relative channel quality level of each coordinated cell is calculated according to a preset algorithm.

In the foregoing solution, the determining, according to a CQI difference between the primary cell and each coordinated cell, determining a relative channel quality of each coordinated cell, according to: a CQI difference between the primary cell and each coordinated cell, and a preset Determining a relative channel quality level of each coordinated cell according to a CQI difference level and a relative channel quality level; or calculating a relative channel of each coordinated cell according to a preset algorithm according to a CQI difference between the primary cell and each coordinated cell quality level.

In the foregoing solution, the determining, according to the relative channel quality of each coordinated cell, the PMI bit of each coordinated cell channel, is: corresponding to a PMI bit from a preset relative channel quality level according to a relative channel quality level of each coordinated cell. The PMI bit of each cooperative cell channel is queried in the relationship table. In the above solution, the determining, according to the relative channel quality of each coordinated cell, the PMI bit of each coordinated cell channel, including:

The relative channel quality level of the coordinated cell is divided into four levels, and the relative channel quality levels respectively correspond to PMI bits of the coordinated cell channel are 1, 2, 3, and 4, and each relative channel quality level is established between each PMI bit. - the corresponding relationship table;

According to the relative channel quality level of each coordinated cell, the PMI bit of each coordinated cell channel is queried from the relationship table between the established relative channel quality level and each coordinated cell channel PMI bit.

In the above solution, the method further includes: obtaining CQI of the primary cell by using fixed bit quantization, and obtaining CQI of each coordinated cell by using fixed bit quantization, and feeding back the quantized CQI of the primary cell and the CQI of each coordinated cell to Primary cell base station.

In the above solution, the CQI of the primary cell is obtained by using fixed bit quantization, and the CQI of the primary cell is obtained by using 4-bit quantization.

In the above solution, the CQI of each coordinated cell is obtained by using fixed bit quantization, and the CQI of each coordinated cell is quantized by using any fixed bit smaller than 4 bits.

In the above solution, the CQI of each coordinated cell is obtained by using fixed bit quantization, and the CQI of each coordinated cell is obtained by using 2-bit quantization.

The present invention also provides a channel information feedback device, where the device includes: a quantization unit and a feedback unit, where

a quantization unit, configured to quantize a PMI of the primary cell channel according to a fixed bit; and, for determining a PMI bit of each coordinated cell channel according to a relative channel quality of each coordinated cell, and obtaining a PMI of each coordinated cell channel;

And a feedback unit, configured to feed back a PMI of the primary cell channel and a PMI of each coordinated cell channel quantized by the quantization unit to the primary cell base station.

In the above solution, the apparatus further includes: a determining unit, configured to determine a relative channel quality level of each coordinated cell according to an SNR difference value or a CQI difference value between the primary cell and each coordinated cell; The quantization unit is further configured to query, according to a relative channel quality level of each coordinated cell determined by the determining unit, a PMI bit of each coordinated cell channel from a preset correspondence table of relative channel quality levels and PMI bits.

In the above solution, the quantization unit is further configured to obtain a CQI of the primary cell by using fixed bit quantization, and obtain a CQI of the coordinated cell by using fixed bit quantization;

The feedback unit is further configured to feed back the CQI of the primary cell and the CQI of each coordinated cell obtained by the quantization unit to the primary cell base station.

The channel information feedback method and device provided by the present invention determines the PMI bits of each coordinated cell channel according to the relative channel quality of each coordinated cell, and quantizes the PMI of each coordinated cell channel, thereby implementing adaptive quantization of the coordinated cell channel information, thereby The feedback amount of the channel information can be controlled according to actual needs, and the feedback of the cell information of the multiple channels of the CoMP system can be effectively reduced, and the feedback amount and system overhead can be effectively reduced, thereby saving resources.

In addition, after acquiring the channel information fed back by the UE, the primary cell base station may further determine the relative channel quality of the coordinated cell channel according to the acquired channel information, so as to better understand the current channel quality condition. DRAWINGS

1 is a schematic diagram of a scenario of a CoMP system;

2 is a schematic diagram of a scenario of another CoMP system;

3 is a flowchart of implementing a channel information feedback method according to the present invention;

FIG. 4 is a schematic structural diagram of a channel information feedback apparatus according to the present invention. detailed description

The CoMP system has the following two characteristics: First, the number of cooperative base stations changes dynamically; Second, each base station has different path loss to the UE, so that the energy of each base station to reach the UE is different, and the channel of the primary cell generally has higher energy. . The CoMP system shown in Figures 1 and 2 includes The two base stations and the UE, the UE can measure the channel information of each base station to itself and feed back to each base station. In the CoMP system shown in FIG. 1, the UE is close to the base station of the primary cell, and is far away from the base station of the coordinated cell. The channel quality of the coordinated cell is lower than the channel quality of the primary cell. In the CoMP system shown in FIG. 2, the UE is at the edge of the primary cell, and the distance between the UE and the base station of the primary cell is similar to the distance between the base station of the coordinated cell. At this time, the channel quality of the coordinated cell will be close to the channel quality of the primary cell.

The basic idea of the present invention is: the UE uses fixed bit quantization for the primary cell channel information, and the coordinated cell channel information is quantized according to its relative channel quality, where the relative channel quality refers to the coordinated cell channel quality and the primary cell channel quality. Quantizing the difference, that is, allocating different bits according to the energy of the base station to the UE, so that not only the dynamic change of the number of coordinated base stations of the CoMP system but also the different energy of each base station to reach the UE can be utilized, and the multiple cells can be greatly reduced. The amount of feedback when channel information is fed back, the present invention can be applied to various scenarios such as joint transmission and cooperative beamforming of CoMP, and both channel direction quantization and precoding vector quantization can be employed.

Referring to FIG. 3, the channel information feedback method of the present invention may further include: Step 101: Quantify a PMI of a primary cell channel according to a fixed bit (bit), and determine a channel of each coordinated cell according to a relative channel quality of each coordinated cell. PMI bits are quantized to obtain a PMI of each coordinated cell channel;

Here, the relative channel quality represents a quantized difference between a channel quality of the coordinated cell and a channel quality of the primary cell.

Step 102: Feed back the quantized PMI of the primary cell channel and the PMI of each coordinated cell channel to the primary cell base station.

Specifically, the PMI of the primary cell channel can be quantized according to a fixed 4-bit quantization according to the existing channel information feedback protocol.

Here, step 101 may further include: according to a signal to noise ratio between the primary cell and each coordinated cell (SNR) difference or CQI difference, determining the relative channel quality level of each coordinated cell. Specifically, determining a relative channel quality of each coordinated cell according to an SNR difference between the primary cell and each coordinated cell; or determining a relative channel quality of each coordinated cell according to a CQI difference between the primary cell and each coordinated cell. .

In practical applications, determining the PMI bit of each coordinated cell channel can be implemented in the following two ways:

First, measuring the SNR of the primary cell and the SNR of each coordinated cell, determining the relative channel quality level of each coordinated cell according to the SNR difference between the primary cell and each coordinated cell, and then according to the relative channel quality level of each coordinated cell, Querying PMI bits of each coordinated cell channel from a preset correspondence table of relative channel quality levels and PMI bits;

Specifically, determining a relative channel quality level of each coordinated cell according to a SNR difference between the primary cell and each coordinated cell and a preset SNR difference threshold, and corresponding to a PMI bit according to a preset relative channel quality level. Determining a PMI bit of each coordinated cell channel; or, according to a SNR difference between the primary cell and each coordinated cell, calculating a relative channel quality level of each coordinated cell according to a preset algorithm, and according to a preset relative channel quality level Corresponding to the PMI bit, the PMI bit of each coordinated d, zone channel is determined.

For example, four SNR difference thresholds may be set, such as a first SNR difference threshold, a second SNR difference threshold, a third SNR difference threshold, and a fourth SNR difference threshold, if the obtained SNR difference is at the first Between the SNR difference threshold and the second SNR difference threshold, determining that the relative channel quality level of the coordinated cell is 1, and then using the PMI bit corresponding to the relative channel quality level 1 to obtain the PMI of the coordinated cell channel, if the obtained The SNR difference is between the second SNR difference threshold and the third SNR difference threshold, and then determining that the relative channel quality level of the coordinated cell is 2, and the PMI bit corresponding to the relative channel quality level 2 is used to obtain the coordinated cell channel. PMI.

Second, the SNR of the primary cell and the SNR of each coordinated cell are measured, and according to the mapping relationship between the signal-to-noise ratio and the CQI, the CQI of the primary cell and the CQI of each coordinated cell are obtained, and then according to Determining the relative channel quality of each coordinated cell according to the CQI difference between the primary cell and each coordinated cell; and finally, according to the relative channel quality level of each coordinated cell, from the correspondence table between the preset relative channel quality level and the PMI bit Query the PMI bits of each coordinated cell channel.

Specifically, determining a relative channel quality level of each coordinated cell according to a CQI difference value between the primary cell and each coordinated cell, and a preset CQI difference level and a relative channel quality level correspondence, and according to a preset relative channel The correspondence between the quality level and the PMI bit determines the PMI bit of each coordinated cell channel.

Or, according to the CQI difference between the primary cell and each coordinated cell, calculate a relative channel quality level of each coordinated cell according to a preset algorithm, and determine each collaboration according to a preset correspondence between the relative channel quality level and the PMI bit. d. PMI bit of the zone channel.

According to the existing channel information feedback protocol, the PMI of the primary cell channel is quantized by 4 bits. In order to be compatible with the existing channel information feedback protocol, the PMI of each coordinated cell channel needs to be quantized by using 1-4 bits, correspondingly, The relative channel quality of each coordinated cell is divided into four levels, each level of the relative channel quality corresponds to one PMI bit, and the relative channel quality levels respectively correspond to PMI bits of the coordinated cell channel are 1, 2, 3, 4, and are established. Corresponding relationship table between the relative channel quality level and the PMI bit, for example, a correspondence relationship as shown in Table 1 can be established.

Table 1

In this way, the PMI bits of each coordinated cell channel can be queried from the established correspondence table between the relative channel quality level and the PMI bits of each coordinated cell according to the relative channel quality level of each coordinated cell.

For example, the CQI may be divided into four levels, and each CQI level corresponds to a relative channel quality level, and a correspondence table between the CQI level and the relative channel quality level is established, according to the association. Determining the CQI difference between the cell channel and the primary cell, determining the CQI level of the coordinated cell, and querying the relative channel quality level corresponding to the determined CQI level from the correspondence table between the CQI level and the relative channel quality level, thereby obtaining cooperation The relative channel quality of the cell.

For another example, the relative channel quality level Δ of the coordinated cell can be calculated according to the formula (1) by the CQI difference ACQ' of the coordinated cell and the primary cell.

^Δ = L ^A CQI / 4" (丄) where L ′′ is rounded down, ^Δ∞ι ≡ { 0, ... , 15 }, thus, there are AG { 0, 1 , 2, 3 }.

The relative channel quality level Δ is calculated by using the above formula (1), and the accuracy of Δ is increased, especially when the CQI of the primary cell and the CQI of the coordinated cell are not much different, but it is in the case of two CQI levels respectively. In the following, it is more suitable to determine the relative channel quality of the coordinated cell by using Equation (1).

In an actual application, the foregoing method may further include: obtaining a CQL of the primary cell by using fixed bit quantization, and obtaining a CQI of each coordinated cell by using fixed bit quantization, and feeding back the quantized CQI of the primary cell and the CQI of each coordinated cell to the primary cell. Base station.

The process of feeding back the channel information is implemented by the UE. Specifically, the CQI of the primary cell can be obtained by 4-bit quantization, and the CQI of each coordinated cell can be quantized by using any fixed bit smaller than 4 bits. For example, the CQI of each coordinated cell can be obtained by 2-bit quantization.

Correspondingly, the present invention further provides a channel information feedback device. As shown in FIG. 4, the device includes: a quantization unit 41 and a feedback unit 42, where the quantization unit 41 is configured to quantize the primary cell channel according to fixed bits. PMI; and, for determining a PMI bit of each coordinated cell channel according to a relative channel quality of each coordinated cell, and quantizing a PMI of each coordinated cell channel; and a feedback unit 42 for feeding back the quantized main by the quantization unit 41 The PMI of the cell channel and the PMI of each coordinated cell channel are given to the primary cell base station.

The device may further include: a determining unit 43, configured to determine, according to a SNR difference value or a channel quality indicator (CQI) difference between the primary cell and each coordinated cell, a phase of each coordinated cell The quantization unit 41 is further configured to query each collaboration from a preset correspondence table of relative channel quality levels and PMI bits according to a relative channel quality level of each coordinated cell determined by the determining unit 43. PMI bit of the cell channel.

Here, the quantization unit 41 may be further configured to: obtain a CQL of the primary cell by using fixed bit quantization, and obtain a CQI of the coordinated cell by using fixed bit quantization; and the feedback unit 42 may further be used to feed back the obtained by the quantization unit. The CQI of the cell and the CQI of each coordinated cell are given to the primary cell base station.

In an actual application, the device for feeding back channel information may be set on the UE, and the channel information is fed back through the specific description of the foregoing method.

Embodiment 1

In this embodiment, the CoMP system includes a UE, a primary cell base station of the UE, and a coordinated cell base station of the UE. In this embodiment, the UE quantizes the channel information according to the specific quantization scheme shown in Table 2 and provides feedback. The specific process is as follows:

First, the UE may estimate the channel matrix H_0 of the primary cell and the channel matrix H_l of the coordinated cell according to the reference signal;

Second, the UE quantizes the channel information of the primary cell and the channel information of the coordinated cell according to the specific quantization scheme shown in Table 2;

Specifically, for the primary cell: In order to be consistent with the Long-Term Evolution (LTE) system, the primary cell channel information including the 4-bit CQI_0 and the 4-bit PMI_0 is quantized according to the channel matrix H_0 of the primary cell.

For the coordinated cell: the SNR of the primary cell and the SNR of the coordinated cell are obtained, and according to the mapping relationship between the SNR and the CQI, the CQI value of the primary cell and the CQI value of the coordinated cell are obtained, and the CQI between the coordinated cell channel and the primary cell channel is obtained. a difference, which in turn determines a relative channel quality level Δ, { 0, 1 , 2, 3 } of the coordinated cell; according to the relative channel quality level difference A, the quantization bit of the PMI_1 of the coordinated cell channel is determined according to the specific quantization scheme shown in Table 2 In this embodiment, Determining the relative channel quality level difference A is 2, and the PMI_1 bit is 2, as shown in Table 2, in this embodiment, the CQI_1 is quantized by 2 bits; then, according to the channel matrix H_l of the coordinated cell, the quantization includes 2 bits. Cooperative cell channel information of CQI_0 and 2bit PMI_1.

Table 2

Finally, the UE will quantize the obtained primary cell channel information including the 4-bit CQI_0 and the 4-bit PMI_0, and the coordinated cell channel information including the 2-bit CQI_0 and the 2-bit PMI_1 to the primary cell base station.

As shown in Table 2, in this embodiment, when the relative channel quality level Δ is 0, the bit that needs feedback is the largest, which is 4 bits. At this time, the channel quality of the coordinated cell is close to the local channel quality, which is of equal importance. As the relative channel quality level difference A becomes larger, the quantized bits become smaller, and the relative channel quality level Δ corresponds to the PMI bit, and when the coordinated cell channel quality is relatively low, it can be quantized with fewer bits. In this way, adaptive quantization based on the relative channel quality not only effectively reduces the amount of feedback, but also when the primary cell base station knows the PMI bit, it can also determine the relative channel quality level A of the current coordinated cell channel, thereby better understanding the current Channel quality status.

The above specific quantization scheme is only a reference and can be improved according to the actual application. For example, when the relative channel quality level A is 3, that is, when the coordinated cell channel quality is poor, the CQI_1 can be quantized only by lbit. It should be noted that, in this embodiment, the PMI may be either a precoding vector or a channel direction vector, and is related to a specific transmission scheme.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A channel information feedback method, the method comprising:

Obtaining a precoding matrix indication PMI of the primary cell channel according to the fixed bit quantization; determining a PMI bit of each coordinated cell channel according to a relative channel quality of each coordinated cell, and obtaining a PMI of each cooperative cell channel;

The channel information feedback method according to claim 1, wherein the PMI of the primary cell channel is quantized according to the fixed bit, and the PMI of the primary cell channel is obtained according to a fixed 4-bit quantization.

The channel information feedback method according to claim 1, wherein the method further comprises: determining a relative of each coordinated cell according to a SNR difference between the primary cell and each coordinated cell or a CQI difference indicating a channel quality. Channel quality level.

The channel information feedback method according to claim 3, wherein the determining the relative channel quality of each coordinated cell according to the SNR difference between the primary cell and each coordinated cell is: according to the primary cell and each collaboration Determining the relative channel quality level of each coordinated cell by using the SNR difference between the cells and the preset SNR difference threshold; or calculating the cooperation according to a preset algorithm according to the SNR difference between the primary cell and each coordinated cell The relative channel quality level of the cell.

The channel information feedback method according to claim 3, wherein the determining a relative channel quality of each coordinated cell according to a CQI difference between the primary cell and each coordinated cell is: according to the primary cell and each collaboration Determining a relative channel quality level of each coordinated cell by using a CQI difference value between the cells, and a preset CQI difference level and a relative channel quality level correspondence relationship; Or, according to the CQI difference between the primary cell and each coordinated cell, the relative channel quality level of each coordinated cell is calculated according to a preset algorithm.

The channel information feedback method according to claim 4 or 5, wherein the determining, according to the relative channel quality of each coordinated cell, the PMI bit of each coordinated cell channel is: according to the relative channel quality level of each coordinated cell The PMI bit of each coordinated cell channel is queried from a correspondence table of pre-set relative channel quality levels and PMI bits.

The channel information feedback method according to claim 6, wherein the determining the PMI bit of each coordinated cell channel according to the relative channel quality of each coordinated cell includes:

The channel information feedback method according to claim 1, wherein the method further comprises: obtaining a CQI of the primary cell by using fixed bit quantization, and obtaining a CQI of each coordinated cell by using fixed bit quantization, and obtaining the quantized result. The CQI of the primary cell and the CQI of each coordinated cell are fed back to the primary cell base station.

The channel information feedback method according to claim 8, wherein the CQI of the primary cell is obtained by using fixed bit quantization, and the CQI of the primary cell is obtained by using 4-bit quantization.

The channel information feedback method according to claim 9, wherein the CQI of each coordinated cell is obtained by using fixed bit quantization, and the CQI of each coordinated cell is obtained by using any fixed bit quantization of less than 4 bits.

The channel information feedback method according to claim 10, wherein the CQI of each coordinated cell is obtained by using fixed bit quantization, and the CQI of each coordinated cell is obtained by using 2-bit quantization.

12. A channel information feedback device, the device includes: a quantization unit and a feedback unit, where

The channel information feedback device according to claim 12, wherein the device further comprises: a determining unit, configured to determine, according to a SNR difference or a CQI difference between the primary cell and each coordinated cell, each coordinated cell Relative channel quality level;

The quantization unit is further configured to query, according to a relative channel quality level of each coordinated cell determined by the determining unit, a PMI bit of each coordinated cell channel from a preset correspondence table of relative channel quality levels and PMI bits.

14. The channel information feedback apparatus according to claim 12, wherein:

The quantizing unit is further configured to obtain a CQI of the primary cell by using fixed bit quantization, and obtain a CQI of the coordinated cell by using fixed bit quantization;