Adaptive Equalizer Tap Pruning for Changing Wireless Channels
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Solution Overview
Problem
Existing channel equalization methods in wireless communication systems face challenges in efficiently updating coefficients to match changing channel conditions, leading to suboptimal performance due to fixed equalizer lengths and dynamic channel characteristics.
Innovation Solution
The implementation of a baseband processing module that employs frequency domain equalization techniques, including MMSE weight calculation and tap ordering, to generate and update equalizer coefficients dynamically, allowing for improved adaptation to changing channel conditions through the use of multiple RF front ends and diversity paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed length equalizer is used, then device complexity is reduced, but equalization accuracy deteriorates due to mismatch with changing channel conditions
Solution Approach 1:
The patent implements dynamic equalizer length adjustment by continuously monitoring channel impulse response and adapting the equalizer length to match the actual channel characteristics. This allows the equalizer to transition from a fixed structure to a dynamic one that adapts to changing channel conditions, resolving the contradiction between fixed structure simplicity and adaptive performance accuracy.
Solution Approach 2:
The patent changes the parameter of equalizer length from a fixed value to a dynamically adjustable parameter based on channel conditions. By monitoring channel impulse response and adjusting the equalizer length parameter accordingly, the system achieves both computational efficiency (when channel is simple) and equalization accuracy (when channel is complex).
2Reliability
If equalizer coefficients are continually updated, then equalization performance is improved, but processing time and complexity increase
Solution Approach 1:
The patent implements periodic updating of equalizer coefficients based on channel condition changes rather than continuous updating. By detecting significant channel variations and triggering coefficient updates only when necessary, the system maintains equalization performance while reducing unnecessary processing time and computational overhead.
Solution Approach 2:
The system performs self-adjustment by automatically detecting channel condition changes and triggering coefficient updates only when performance degradation is detected. This self-service mechanism reduces processing time by avoiding unnecessary updates while maintaining reliability through adaptive response to actual channel conditions.
Data Source
AI summary
A baseband processing module of a Radio Frequency receiver produces time domain equalizer coefficients and calculates a power threshold based upon a total power of a plurality of taps of the time domain equalizer coefficients. The baseband processing module then performs a plurality of iterations, during each of which it identifies at least one minimum power tap and determines a total power figure based upon zeroing the at least one minimum power tap. When the total power figure compares favorably to the power threshold, the baseband processing module modifies the plurality of taps by zeroing the at least one minimum power tap and continuing iterating. When the total power figure compares unfavorably to the power threshold, the baseband processing module ceases iterating without modifying the plurality of taps by zeroing the at least one minimum power tap and then produces modified time domain equalizer coefficients.