Alamouti Coding and Beamforming for MAS Coverage
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Solution Overview
Problem
Multiple Antenna Systems (MAS) face limitations in achieving uniform Bit Error Rate (BER) across different directions due to limited and fixed antenna patterns, resulting in suboptimal full coverage performance for common channels in wireless communication systems.
Innovation Solution
The implementation of Alamouti coding to form two branches of common channel symbols, followed by the selection of uncorrelated weight vectors for beamforming, which generates spatial diversity and ensures equal signal quality in all directions by superimposing the signals from these branches on each antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple complementary weight vectors are used in turn in successive timeslots, then full cell/sector coverage is realized, but the antenna patterns are fixed and the average values of antenna gains are not equal, causing big differences in BER in each direction
Solution Approach 1:
The patent applies dynamics by making the weight vectors changeable rather than fixed. Specifically, the weight vectors are adjusted based on the actual channel state information, allowing the beamforming weights to adapt dynamically to different channel conditions and directions, thereby achieving uniform signal quality across all directions while maintaining full coverage
Solution Approach 2:
The patent changes the parameters of the weight vectors based on channel state information. By adjusting the weight vector parameters (amplitude and phase) according to actual channel conditions, the system optimizes the antenna gain distribution to achieve equal average values across different directions, resolving the BER uniformity issue
2Device complexity
If fixed weight vectors are used for beamforming, then the system complexity is reduced, but the BER performance varies significantly in different directions
Solution Approach 1:
The patent implements feedback by using channel state information to adjust the weight vectors. The system receives feedback about the channel conditions and uses this information to optimize the beamforming weights, ensuring uniform BER performance across different directions while managing system complexity through efficient feedback utilization
Data Source
AI summary
A method and apparatus for transmitting signals in a Multiple Antennas System (MAS) are disclosed. The method includes performing Alamouti coding on each group of common channel symbols to form two branches; selecting different weight vectors for different branches to perform beamforming, obtaining transmitting signals of each branch on each antenna, where beam modes corresponding to different weight vectors are uncorrelated and the peak-to-average power ratio of angle dimension of the two beam modes are lower than a preset threshold; and superimposing the transmitting signals of these two branches on each antenna, and transmitting the superimposed signals. In the present invention, the Alamouti coding is introduced, and a spatial diversity gain is generated by using the independence of two virtual channels. Thus, the performance of the MAS in full coverage is enhanced.