Diversity Signal Alignment in Communication Receivers
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Solution Overview
Problem
Diversity-based communication receivers face challenges in symbol alignment due to delay variations and sampling phase mismatches, leading to less-than-optimum results in interference cancellation and receiver performance, especially in GSM/EDGE networks where co-channel interference is significant.
Innovation Solution
A method for symbol alignment in communication receivers that involves generating diversity sample sets, hypothesizing relative symbol alignments, and jointly determining the preferred synchronization position and alignment by evaluating correlation responses to maximize correlation with a known training sequence, thereby improving computational efficiency and receiver performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If diversity signals are assumed to be naturally symbol aligned, then processing complexity is reduced, but receiver performance deteriorates due to misalignment from delay variations and sampling phase mismatches
Solution Approach 1:
The patent applies parameter changes by adjusting the relative symbol alignment between diversity signals based on evaluated metrics. Instead of assuming fixed natural alignment, the system dynamically modifies alignment parameters to optimize receiver performance while managing computational complexity through selective evaluation of alignment hypotheses.
2Reliability
If multiple receiver antennas are used to provide diversity signals, then receiver performance improves, but device size and cost increase
Solution Approach 1:
The patent uses copying by creating virtual diversity signals through over-sampling the received signal at multiple phases. Instead of requiring multiple physical antennas, the system generates multiple diversity sample sets from a single antenna by sampling at different phases, thereby achieving diversity reception without increasing device size.
3Reliability
If over-sampling is used to create diversity signals, then interference cancellation performance improves, but symbol misalignment increases due to sampling phase mismatches
Solution Approach 1:
The patent implements feedback by evaluating the alignment of diversity signals and using the evaluation results to adjust subsequent processing. The system calculates metrics based on hypothesized alignments, uses these evaluations to determine optimal alignment, and applies corrections to improve both interference cancellation and symbol alignment accuracy.
4Reliability
If joint determination of symbol alignment and synchronization position is performed, then receiver performance improves, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the joint determination problem into separate evaluation stages. The system first evaluates relative symbol alignment based on hypothesized alignments, then determines synchronization position based on the alignment evaluation results. This segmented approach reduces computational complexity compared to exhaustive joint optimization while maintaining performance benefits.
Data Source
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AI summary
Methods and apparatus taught herein provide for symbol alignment between diversity signals in a communication receiver. A method of symbol aligning diversity signals in a communication receiver comprises generating diversity sample sets for a received signal and hypothesizing two or more relative symbol alignments for the diversity sample sets. The method further includes jointly determining a preferred relative symbol alignment and a preferred synchronization position for the diversity sample sets by evaluating a function that is dependent on relative symbol alignment and synchronization position according to the hypothesized relative symbol alignments and a number of candidate synchronization positions.