Space-Time Filter Weights Using QR Decomposition
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Solution Overview
Problem
Current Global System for Mobile (GSM) cellular systems face challenges in addressing co-channel interference (CCI) on the mobile station side and meeting Downlink Advanced Receiver Performance (DARP) requirements, with existing solutions either providing incomplete interference cancellation or increased complexity.
Innovation Solution
A multi-channel, space-time filter circuit that jointly estimates space-time filter weights and channel impulse responses using QR decomposition, combined with a multi-channel matched filter circuit, which can switch between standard and matched filter modes based on interference levels, to effectively cancel co-channel interference and improve receiver performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If joint demodulation with maximum likelihood estimation is used to achieve optimal performance, then receiver performance is improved, but computational complexity increases significantly
Solution Approach 1:
The patent changes the parameter of channel estimation by using reduced-rank approximation instead of full-rank maximum likelihood estimation. This transforms the computational problem from O(N^3) to O(N^2) complexity while maintaining acceptable performance, directly resolving the contradiction between optimal performance and computational complexity
Solution Approach 2:
The patent uses simpler, computationally cheaper estimation methods (reduced-rank approximation) that can be rapidly computed and updated, replacing the need for complex, computationally expensive maximum likelihood estimation while achieving sufficient performance for practical applications
2Object-affected harmful factors
If single-channel space-time filtering is used to reduce interference, then interference cancellation is improved, but multi-channel interference cancellation capability deteriorates
Solution Approach 1:
The patent designs a space-time filter that processes multiple channels simultaneously through joint demodulation, making the filter universal across different channels. The filter weights are computed to handle multi-channel interference while maintaining the ability to process each channel's signal, thus improving both interference cancellation and multi-channel capability
3Device complexity
If conventional matched filters are used for simplicity, then device complexity is reduced, but interference cancellation performance deteriorates
Solution Approach 1:
The patent introduces adaptive space-time filtering where filter weights are dynamically computed based on channel conditions and interference characteristics. Unlike static conventional matched filters, the adaptive filter adjusts its parameters to optimize interference cancellation performance while maintaining manageable complexity through structured weight computation
Data Source
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AI summary
A wireless communications device may include a wireless transmitter and a wireless receiver. The wireless receiver may include a filter for reducing co-channel interference and may include a multi-channel, space-time filter circuit that filters n signal parts that have been split from a communications signal by jointly estimating space-time filter weights and multi-channel impulse responses (CIRs) based upon QR and eigenvalue decompositions. The filter may further include a multi-channel, matched filter circuit that receives multi-channel signals from the multi-channel, space-time filter circuit and has a filter response that is provided by a channel impulse response estimation from the space-time filter circuit.