Joint Space-Time Filtering for GSM Co-Channel Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Global System for Mobile (GSM) cellular systems face challenges in addressing co-channel interference (CCI) on the mobile station side while meeting the requirements of Downlink Advanced Receiver Performance (DARP) standardized by the Third Generation Partnership Project (3GPP, with existing solutions not providing sufficient performance in interference cancellation and channel impulse response estimation.
Innovation Solution
A Joint Space-Time Optimum Filter (JSTOF) based receiver is introduced, which includes a multi-channel, space-time filter circuit that jointly estimates space-time filter weights and channel impulse responses, and a multi-channel matched filter circuit, capable of adaptive interference cancellation and channel impulse response estimation, using a virtual antenna array and auto-switching between JSTOF and conventional filters based on interference levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single channel filters are used for interference cancellation, then device complexity is reduced, but interference cancellation performance and channel impulse response estimation accuracy deteriorate
Solution Approach 1:
The patent transitions from single-channel filtering to multi-channel space-time filtering by introducing multiple antenna elements and temporal processing dimensions. The joint space-time filter processes signals across multiple spatial channels and time delays simultaneously, achieving superior interference cancellation and channel estimation performance by utilizing the additional spatial and temporal dimensions available in MIMO systems.
Solution Approach 2:
The patent merges the interference cancellation function and channel impulse response estimation function into a single joint optimization framework. Instead of treating these as separate processing stages, the joint space-time filter simultaneously performs both functions by optimizing a unified cost function that considers both interference suppression and channel estimation accuracy, leading to improved overall system performance.
2Measurement precision
If joint space-time filtering is implemented for both interference cancellation and channel estimation, then estimation accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent segments the joint space-time filtering problem into manageable computational components by utilizing the structured properties of the received signal model. The filter decomposes the complex joint estimation task into operations on correlation matrices and signal subspaces, enabling efficient computation through matrix factorization techniques that exploit the inherent structure rather than treating the problem as a general high-dimensional optimization.
Solution Approach 2:
The patent changes the parameter representation and optimization approach by formulating the joint filter design in terms of correlation matrices and eigenvalue decompositions rather than direct optimization of filter coefficients. This parameter transformation converts a computationally intensive problem into one that can be solved efficiently using standard linear algebra operations, reducing the computational burden while maintaining estimation accuracy.
Data Source
Figure 1
Figure 2
Figure 2A
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). 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.