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Feedback method for channel state information

A technology for channel state information and channel conditions, applied in space transmit diversity, digital transmission systems, electrical components, etc., can solve problems such as large system errors, increased PMI index feedback overhead, resource occupation, etc., to improve bit error rate performance , the effect of reducing feedback overhead and reducing the size of the codebook

Inactive Publication Date: 2014-11-12
BEIJING SAMSUNG TELECOM R&D CENT +1
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AI Technical Summary

Problems solved by technology

[0003] The codebook is pre-designed. In order to ensure the precoding performance, the codebook size required for codebook-based precoding increases with the number of antennas, and the feedback overhead of the PMI index also gradually increases, thus occupying resources used for data transfer, which in turn reduces system performance
At the same time, for the new transmission mode for large-scale antennas and the supporting new double-layer (or single-layer) codebook scheme, considering the maximum payload of the PUCCH channel, it may not be possible to allocate the required resources for the transmission of the PMI index, thus reducing the The accuracy of precoding matrix selection is affected, which affects system performance
[0004] In addition, most of the existing precoding operations are based on the premise of the correct feedback of the PMI index
However, in practical systems, the UE feeds back the PMI to the base station through the uplink, which is susceptible to noise during transmission
If the PMI index is not assigned properly, even a small transmission error (such as 1 bit error) may cause a large system error

Method used

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Embodiment 1

[0038] It is assumed that the currently used standard codebook is a two-layer codebook, wherein the first layer codebook is a Kerdock codebook, and the second layer codebook is a perturbation based on Discrete Fourier (DFT). The first layer codebook is the main codebook, and the second layer codebook is the auxiliary codebook. For this double-layer codebook, it contains more precoding matrices than the single-layer codebook, and the number of PMI bits to be fed back also increases accordingly. In order to balance the performance and overhead of the system, sub-sampling is performed on the double-layer codebook , to reduce the size of the codebook.

[0039]When sub-sampling is performed specifically, sub-sampling may be performed on any layer of the codebook in the two-layer codebook, or sub-sampling may be performed on both layers at the same time. Considering the impact of codebook sub-sampling on system performance, preferably, sub-sampling can only be performed on the code...

Embodiment 2

[0069] Assume that a two-layer codebook is currently used: it belongs to the discrete Fourier (DFT) two-layer codebook, and is aimed at a uniform rectangular array (URA) 8×4 layout of 32 single-polarized antenna elements (see figure 2 ), considering the unreliability of the uplink feedback channel, the codebook rearrangement mechanism under the channel feedback error is carried out on the double-layer codebook.

[0070] The expression of the first layer codebook precoding matrix is ​​as follows:

[0071] W 1 ( i 1 ) = D g x x ⊗ D g y y , g x = 0,1 , . . . , G ...

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Abstract

The invention discloses a feedback method for channel state information. The feedback method includes the steps that UE receives a mode which is configured by a base station and used for reporting the channel station information (CSI); the UE measures a base station signal and interference, determines a rank, pre-coding matrixes and CQI used for downlink transmission under the current channel condition and obtains PMIs for instructing the pre-coding matrix according to the pre-coding matrixes; the UE reports the rank, the PMIs and the CQI in the uplink direction. A codebook used for feeding back the CSI is a sub-codebook of a standard codebook, and the higher the correlation between any two codes in the codebook is, the smaller the code distance between the two corresponding PMIs is. The feedback method can be applied to improving the transmission performance of a system.

Description

technical field [0001] The present application relates to the technical field of wireless mobile communication, and in particular to a channel state information (CSI) feedback method. Background technique [0002] In a multiple-input multiple-output (MIMO) system, in order to perform precoding at the transmitting end to improve system transmission performance, the transmitting end needs to know channel state information (CSI), which usually requires the receiving end to feed back the CSI. However, the bandwidth of the PUCCH channel used to carry the CSI feedback is limited, so the current common way is to design a codebook for precoding and save it at the transmitting end and the receiving end. The codebook includes many codewords, ie, precoding matrices. When performing CSI feedback, the receiving end determines the adopted precoding matrix by feeding back a precoding matrix indicator (PMI) index to the transmitting end. [0003] The codebook is pre-designed. In order to ...

Claims

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Application Information

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IPC IPC(8): H04L1/00H04B7/04
Inventor 粟欣曾捷方娜燕容丽萍孙程君李迎阳
Owner BEIJING SAMSUNG TELECOM R&D CENT
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