Quantized Beamforming for Multi-User Diversity Gain
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Solution Overview
Problem
Existing beam forming methods, such as opportunistic beam forming (OBF), face limitations in achieving multi-user diversity gain when the number of users is small and result in reduced system capacity due to the use of multiple pilots.
Innovation Solution
A beam forming method and apparatus that utilize a quantization preprocessor and a random unitary matrix to select the most suitable mobile terminal for data transmission, improving OBF performance by estimating channel gains and optimizing codeword selection, thereby enhancing system efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opportunistic beam forming (OBF) scheme is used to obtain diversity gain, then multi-user diversity gain increases, but it requires a large number of users to achieve sufficient gain
Solution Approach 1:
The patent changes the parameter of beam formation by introducing a quantization preprocessor that generates multiple candidate beams with different directions and widths. This allows the system to adapt beam parameters dynamically to exploit multi-user diversity even with fewer users, resolving the contradiction between achieving diversity gain and requiring many users
Solution Approach 2:
The system dynamically selects from multiple quantized beam candidates based on real-time channel conditions and user distribution. This dynamic adaptation enables the system to achieve diversity gain by rapidly changing beam directions to track favorable channel conditions, overcoming the limitation of requiring many static users
2Reliability
If multiple pilots are used to improve diversity in pilot selection, then diversity gain increases, but system capacity is lowered
Solution Approach 1:
The patent extracts the essential diversity information from multiple pilots through quantization, retaining only the most significant beam candidates. This extraction approach maintains diversity benefits while reducing the overhead of transmitting and processing multiple full pilots, thereby preserving system capacity
Solution Approach 2:
Instead of using all possible pilots, the system uses a quantized subset of beam candidates that provides sufficient diversity. This partial action approach achieves the necessary diversity gain without the excessive resource consumption of full multiple pilot schemes, maintaining system capacity
Data Source
AI summary
The present invention relates to a method of forming a random beam, and a beam forming apparatus. A quantization preprocessor and a random unitary matrix having a predetermined pattern are used to form a beam on a mobile terminal. A base station forms a beam using a codeword index of a quantization codebook received from a mobile terminal and channel quality information corresponding to the codeword index, and the mobile terminal generates the codeword index and the channel quality information using pilot signals generated by the base station. The number of pilot signals is equal to the number of transmitting antennas. Therefore, a codebook that has been known to both the mobile terminal and the base station is used, and the mobile terminal can select the codeword index for quantization, which makes it possible to selectively give diversity and thus improve the system efficiency.