Adaptive Codebook Beamforming for Mobility Robustness
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Solution Overview
Problem
Existing wireless communication systems face challenges in providing directional transmission to mobile devices in motion, especially in scenarios where narrow beamforming is required, due to increased complexity and feedback overhead with a large number of antennas, and vulnerability to user mobility and channel variations.
Innovation Solution
The implementation of adaptive codebooks generated based on matrix products of sequences of complex exponentials and base codebooks, with configurable broadening factors, allows for beam-width adjustment and selection based on mobile velocity measurements, enabling efficient directional transmissions by selecting appropriate codewords for antenna arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If narrow beamforming is used to provide directional transmission to mobile devices, then beamforming gain and transmission efficiency are improved, but the system becomes more vulnerable to user mobility and channel variations
Solution Approach 1:
The patent applies dynamics by making the codebook adaptive rather than static. The codebook is generated dynamically based on current channel conditions and mobility measurements, allowing the beamforming system to adjust its characteristics in real-time. This enables the system to maintain narrow beamforming gain when conditions are stable while transitioning to broader beams when mobility increases, thus resolving the contradiction between beamforming gain and robustness.
Solution Approach 2:
The patent changes the parameter of beamwidth by generating codebooks with different broadening factors. The base codebook is modified by applying complex exponential sequences with configurable broadening factors to create adaptive codebooks with varying beamwidths. This allows the system to select appropriate beamwidth parameters based on mobility conditions, achieving both narrow beams for gain and wider beams for robustness as needed.
2Power
If a large number of antennas are used to enhance directional transmission capability, then beamforming performance is improved, but codebook overhead and system complexity increase
Solution Approach 1:
The patent segments the codebook generation process into modular components: a base codebook and adaptive transformations using complex exponential sequences. This segmentation allows the system to handle large antenna arrays by breaking down the codebook into manageable parts that can be generated efficiently. The segmented approach reduces overall codebook overhead while maintaining the ability to support large numbers of antennas for enhanced directional transmission.
Solution Approach 2:
The patent uses dynamic codebook generation where the adaptive codebook is created on-the-fly based on current channel conditions rather than using a fixed, exhaustive codebook. This dynamic approach significantly reduces codebook overhead by only generating the necessary codebook entries for current conditions, while still supporting large antenna arrays for high-performance beamforming.
3Reliability
If adaptive codebooks with configurable broadening factors are implemented, then robustness against mobility is improved, but codebook generation complexity increases
Solution Approach 1:
The patent replaces complex mechanical or exhaustive search-based codebook generation with a mathematical transformation approach using complex exponential sequences. This substitution allows for efficient generation of adaptive codebooks with configurable broadening factors through closed-form mathematical operations rather than exhaustive searches or complex iterative procedures, thus reducing generation complexity while maintaining robustness.
Solution Approach 2:
The patent simplifies codebook generation by parameterizing the broadening factor that controls beamwidth. By changing this single parameter in the complex exponential sequence, the system can generate codebooks with different robustness characteristics without redesigning the entire codebook structure. This parameter-based approach reduces generation complexity while providing flexible adaptation to mobility conditions.
Data Source
AI summary
Embodiments of an Evolved Node-B (eNB), User Equipment (UE) and methods for communication are generally described herein. The eNB may generate a plurality of adaptive codebooks based on a base codebook. Each adaptive codebook may be generated for a different beam-width for directional transmissions by an antenna array. The adaptive codebooks may be generated based at least partly on matrix products of a first matrix based at least partly on a configurable broadening factor and a second matrix that includes codewords of the base codebook. A predetermined plurality of broadening factor values may be used in the first matrix to produce the different beam-widths for the adaptive codebooks.