SVD Space-Time Filtering for Single-Antenna CCI Cancellation
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Solution Overview
Problem
Current Global System for Mobile (GSM) cellular systems face challenges in addressing co-channel interference (CCI) and meeting Downlink Advanced Receiver Performance (DARP) requirements, particularly in scenarios where physical antenna arrays are not available, as existing solutions are inadequate in efficiently canceling interference and providing optimal channel impulse response estimation.
Innovation Solution
A multi-channel, space-time filter circuit is introduced that jointly estimates space-time filter weights and multi-channel impulse responses using singular value decomposition (SVD), coupled with a multi-channel matched filter circuit and an auto-switching mechanism to adapt between standard and interference-canceling modes, enabling effective interference cancellation and channel impulse response estimation even with a single antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single antenna is used, then device complexity is reduced, but interference cancellation capability deteriorates
Solution Approach 1:
The patent creates virtual antenna arrays by copying and processing signal samples at different time instants. Multiple virtual channels are generated from a single physical antenna through temporal sampling and singular value decomposition, enabling interference cancellation without requiring multiple physical antennas.
Solution Approach 2:
The patent transitions from spatial dimension (multiple physical antennas) to temporal dimension (multiple time samples). By processing signals across different time instants and applying SVD in the time domain, the system achieves spatial processing effects using temporal diversity.
2Measurement precision
If joint estimation of filter weights and channel impulse response is performed, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary singular value decomposition on the received signal matrix before channel estimation. This pre-processing step transforms the joint estimation problem into a simpler form where the dominant singular vectors provide initial estimates, reducing the computational burden of subsequent optimization.
Solution Approach 2:
The patent changes the parameter representation by using singular value decomposition to transform the channel estimation problem. Instead of directly estimating channel parameters, the system estimates singular values and vectors, which are then used to derive channel impulse response, simplifying the computational process.
3Device complexity
If standard filter is used when interference level is low, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The patent implements a dynamic switching mechanism that adapts the filter processing mode based on detected interference levels. When interference exceeds a threshold, the system activates the multi-channel SVD-based joint estimation; otherwise, it uses standard filtering, enabling adaptability without constant high complexity operation.
Solution Approach 2:
The system performs self-adaptation by automatically detecting interference conditions and selecting the appropriate processing mode without external control. The interference detection and mode switching are handled autonomously by the receiver, reducing the need for complex external coordination.
Data Source
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AI summary
A filter for reducing co-channel interference within a communications receiver 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 a singular value decomposition (SVD). 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.