Wireless Receiver Impairment Covariance Estimation
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently suppressing interference due to complex signal processing requirements, particularly in calculating impairment covariance matrices, which leads to performance degradation and computational inefficiencies, especially in dual Rake/G-Rake operations and highly dispersive channels.
Innovation Solution
The method involves using path delay information from a path searcher module to determine receiver processing delays, generating net channel coefficients, and regenerating them at arbitrary delays using medium channel coefficients, allowing for a more extensive grid of fingers for interference computation and reducing noise in channel estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques are used to calculate impairment covariance matrices with grid-like finger placement, then interference suppression can be achieved, but device complexity and computational complexity increase significantly
Solution Approach 1:
The patent extracts the essential function of interference suppression from the complex grid-like finger structure. By using a reduced set of fingers with selectively activated elements based on channel conditions, it separates the interference cancellation function from the exhaustive grid search approach, achieving similar performance with fewer resources.
Solution Approach 2:
The patent segments the interference suppression task into two phases: a training phase where impairment covariance matrices are estimated using available fingers, and a data phase where precomputed combining weights are applied. This segmentation eliminates the need for continuous complex computations during data reception, reducing overall device complexity.
2Reliability
If a sufficient number of fingers are allocated for interference suppression calculations, then interference cancellation performance improves, but productivity decreases due to computational overhead
Solution Approach 1:
The patent performs impairment covariance matrix estimation and combining weight computation in advance during a training phase before actual data reception. This preliminary action allows the system to prepare interference suppression parameters beforehand, so that during data processing, only simple weight application is needed, significantly improving productivity.
Solution Approach 2:
The patent computes impairment covariance matrices for a limited set of delay values rather than all possible grid points. By calculating matrices only for delays corresponding to actual multipath components detected in the channel, it performs partial computation that is sufficient for interference suppression without the excessive computational burden of exhaustive grid search.
3Ease of operation
If channel estimates are used to compute interference matrices, then interference suppression can be performed, but measurement precision decreases due to noisy estimates
Solution Approach 1:
The patent performs impairment covariance matrix estimation during a training phase when known training sequences are available, rather than relying solely on channel estimates during data reception. This preliminary estimation uses reliable training data to compute accurate covariance matrices, avoiding the noise contamination that would result from using noisy channel estimates during actual data processing.
4Adaptability or versatility
If dual Rake/G-Rake operation is implemented, then versatility improves for different channel conditions, but device complexity increases
Solution Approach 1:
The patent designs a unified receiver architecture that can operate in both Rake mode and G-Rake mode depending on channel conditions. The same finger structure and impairment covariance estimation mechanism serve both operating modes, eliminating the need for separate dedicated hardware for each mode and reducing overall device complexity while maintaining versatility.
Data Source
AI summary
Path delay information generated by a path searcher module of a wireless receiver is used to generate net channel coefficients for use in suppressing interference from a received signal. According to one embodiment, interference is suppressed from a signal transmitted over a communication channel including transmit and receive pulse shaping filters and a radio channel by generating net channel coefficients for the communication channel at processing delays such as G-Rake finger delays or chip equalizer tap delays. Medium channel coefficients are generated for the radio channel at estimated path delays as a function of the net channel coefficients. The net channel coefficients are regenerated at arbitrary delays as a function of the medium channel coefficients and an impairment covariance estimate is generated based at least in part on the regenerated net channel coefficients.