RAKE Receiver Combining Weights Using Cross-Correlation Statistics
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Solution Overview
Problem
Traditional RAKE receivers in DS-CDMA wireless communication systems face challenges in optimizing RAKE combining weights, which affects signal-to-noise ratio (SNR) due to limitations in accounting for channel estimation errors and noise correlations across multiple signal paths.
Innovation Solution
A method and apparatus for generating RAKE receiver combining weights by determining channel coefficient statistics, channel estimation error statistics, and noise statistics across RAKE fingers, and computing weights based on these statistics to improve the SNR by accounting for correlations and covariances, thereby enhancing the RAKE combining process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RAKE receivers use simple combining weights based only on channel estimates, then the device complexity is reduced, but the signal-to-noise ratio performance deteriorates due to failure to account for channel estimation errors and noise correlations
Solution Approach 1:
The patent changes the parameters used in combining weight computation from simple channel estimates to comprehensive statistics including channel coefficient statistics, channel estimation error statistics, and noise statistics. This parameter expansion enables better SNR performance by accounting for correlations and covariances that were previously ignored.
Solution Approach 2:
The patent introduces combining statistics as an intermediary layer between channel estimation and combining weight computation. These statistics (covariances and correlations) act as mediators that capture the relationships between multiple signal paths, enabling optimal combining without requiring direct complex computation between all channel parameters.
2Reliability
If RAKE receivers account for channel estimation errors and noise correlations across multiple signal paths, then the signal-to-noise ratio is improved, but the computational complexity increases
Solution Approach 1:
The patent segments the combining weight computation into distinct statistical components: channel coefficient statistics, channel estimation error statistics, and noise statistics. Each component is computed and processed separately, then integrated to form the final combining weights. This segmentation manages complexity by breaking down the overall computation into manageable parts.
Solution Approach 2:
The patent performs preliminary computation of combining statistics (covariances and correlations) before the actual combining weight determination. By pre-computing these statistical parameters from the channel estimates and received signals, the system prepares optimized parameters in advance, reducing the computational burden during the critical combining operation.
Data Source
AI summary
A RAKE receiver circuit generates combining weights based on channel estimates and combining statistics that comprise channel coefficient statistics, noise statistics, and channel estimation error statistics. Together, these statistics incorporate the relationships in noise and channel estimation across two or more RAKE fingers, and thus improve combining weight generation. Exemplary determination of statistics comprises channel coefficient cross-correlations, noise cross-correlations, and channel estimation error cross-correlations. Determination of the statistics can be varied based on, for example, the assumption of default or nominal signal models. Further, statistics determination can be configured for different receive and transmit diversity scenarios, wherein combining statistics can be determined on a per diversity signal basis, or jointly for two or more diversity signals, or in a mixed separate/joint method wherein one or more statistics are determined on a per signal basis and one or more statistics are determined across the signals.