PMI Codebook Selection for Flexible LTE Precoding
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Solution Overview
Problem
Current 3GPP LTE systems lack flexible configuration and utilization of PMI (Precoding Matrix Index) according to transmission channel conditions, limiting the effectiveness of precoding in 8-antenna configurations.
Innovation Solution
A method and apparatus that allow user equipment (UE) to select and transmit a precoding matrix from a codebook set tailored to the transmission channel's capability, enabling the base station to search and perform precoding using an identical locally stored codebook set, thereby achieving flexible PMI configuration and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-size codebook set is used for PMI transmission, then the system structure is simple, but the system cannot achieve flexible configuration according to transmission channel conditions
Solution Approach 1:
The codebook set size is made dynamic rather than fixed. The base station configures different大小的 codebook sets (first codebook set with larger size, second codebook set with smaller size) and dynamically selects which codebook set to use based on transmission channel conditions, UE capability, and service requirements, enabling flexible adaptation without permanent system complexity
Solution Approach 2:
The system changes the parameter of codebook set size based on different conditions. By adjusting the codebook set size parameter according to channel quality, UE capability, and service type, the system achieves flexible PMI configuration while maintaining manageable complexity through conditional parameter selection
2Measurement precision
If a larger codebook set is used, then precoding accuracy is improved, but the transmission channel capability requirements increase
Solution Approach 1:
The system applies partial action by selecting appropriate codebook set sizes based on actual needs. Instead of always using the largest codebook set for maximum accuracy, the system uses a smaller second codebook set when channel conditions or UE capability don't require high precision, and only employs the larger first codebook set when necessary, avoiding excessive PMI information transmission
Solution Approach 2:
Different codebook set sizes are applied to different transmission scenarios based on local conditions. The system configures first codebook sets for scenarios requiring high precoding accuracy (good channel conditions, capable UEs) and second codebook sets for scenarios where accuracy requirements are lower, optimizing the balance between precision and information volume for each local context
3Measurement precision
If PMI transmission capacity is increased, then precoding matrix selection precision is improved, but the transmission channel load increases
Solution Approach 1:
The system dynamically adjusts PMI transmission capacity requirements by selecting between different codebook set sizes. When high precision is needed and channel conditions permit, the system uses larger codebook sets with more PMI bits. When precision requirements are lower or channel conditions are poor, it switches to smaller codebook sets, dynamically optimizing the precision-efficiency tradeoff based on real-time conditions
Data Source
AI summary
A method and an apparatus for sending a Precoding Matrix Index (PMI) and performing precoding are provided in the embodiments of the present invention. The method for sending the PMI comprises the following steps: a user equipment acquires the transmission channel capability of carrying the PMI; according to the transmission channel capability of carrying the PMI, the precoding matrices are selected from a locally-stored first codebook set to form a second codebook set; a first precoding matrix is selected from the second codebook set; an index corresponding to the first precoding matrix is sent to a base station over the transmission channel so as to make the base station can find out the first precoding matrix according to the index and precode the data according to the first precoding matrix. The embodiments of the present invention can realize the flexible configuration and use of the PMI.