8-Antenna MIMO Codebook Design Using Phase Rotation
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Solution Overview
Problem
Existing MIMO codebook designs for LTE-Advanced with 8 antennas lack flexibility and efficiency in selecting vectors and phase rotations, leading to suboptimal system performance and limited configurability for different transmission ranks.
Innovation Solution
A new codebook design for 8 antennas is proposed, using a precoding codebook matrix/vector of length 2L, defined as Wnew = G υ W n 1 s 1 φ m W n 2 s 2, where W n = I - 2 u n u n H u n, with L=4, allowing for phase rotations {1, j, -1, -j} and flexible selection of matrices/vectors, enabling more configurable codebook sizes for varying transmission ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the codebook is extended to cover 8 antennas using existing methods, then the number of antennas increases, but the design flexibility and configurability remain limited
Solution Approach 1:
The codebook for 8 antennas is segmented into multiple codebooks corresponding to different transmission ranks (1 to 8). Each codebook is independently optimized and can be selected based on the actual transmission scenario, providing flexible adaptability while covering 8 antennas
Solution Approach 2:
The codebook design dynamically adapts to different transmission ranks by selecting from multiple codebooks. The effective size of the codebook varies with transmission rank, allowing the system to optimize performance for each specific rank rather than using a fixed-size codebook
2Quantity of substance
If additional 2x2 matrices are added to increase vector selection, then more vectors become available, but the codebook complexity increases
Solution Approach 1:
Instead of adding more matrices, the invention changes the phase rotation parameter from {1, -1} to {1, j, -1, -j}, quadrupling the number of available vectors without increasing codebook complexity. This parameter change in the phase factor provides more vector selection flexibility
3Ease of manufacture
If the codebook size is fixed for all transmission ranks, then implementation is simplified, but performance optimization for different ranks is limited
Solution Approach 1:
The codebook design is made dynamic by providing different codebooks for different transmission ranks. The effective codebook size adapts to the transmission rank, allowing performance optimization for each rank while maintaining a systematic structure that is relatively easy to implement
4Device complexity
If phase rotations are limited to {1, -1}, then the codebook structure is simpler, but fewer vectors can be generated
Solution Approach 1:
The phase rotation parameter is changed from the limited set {1, -1} to the expanded set {1, j, -1, -j}. This parameter change quadruples the number of available phase rotations, thereby generating more vectors without fundamentally changing the codebook structure
Data Source
Figure 1
AI summary
A precoding codebook matrix/vector of length 2L is generated by the selection of two matrices/vectors, each from one of a predetermined set of LxL matrices and multiplying each column of one of the matrices/vectors by a complex coefficient.