Cross QAM Symbol Mapping for BER-Based Reliability Classification
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Solution Overview
Problem
The GERAN Evolution system requires an efficient method for symbol mapping in cross M-QAM modulation schemes to improve performance and reliability, particularly in allocating priority data based on bit error rates during transmission.
Innovation Solution
A method and apparatus that classify symbol positions by reliability into higher, medium, and lower categories based on average bit error rates, prioritizing higher-reliability positions for higher-priority symbols, and utilize a cross QAM modulator to rearrange coding symbols accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cross M-QAM modulation scheme is used to increase frequency efficiency, then data transmission capacity is improved, but bit error rate performance deteriorates due to higher order modulation vulnerability
Solution Approach 1:
The patent applies local quality by differentiating the treatment of bit positions within symbols. Different bit positions (e.g., I-component vs Q-component bits) are assigned different reliability weights based on their error susceptibility. The mapping algorithm selectively places more reliable coded bits in positions less prone to errors, thereby optimizing overall system reliability while maintaining high-order modulation benefits
Solution Approach 2:
The patent implements preliminary action by performing bit reliability analysis and position classification before the actual symbol mapping process. The system pre-calculates which bit positions in the constellation diagram are more vulnerable to errors and pre-determines the mapping strategy accordingly, allowing the turbo coder to allocate protection bits strategically before transmission
2Productivity
If higher order modulation (32-QAM, 128-QAM) is adopted to improve spectral efficiency, then data rate is increased, but signal susceptibility to noise and interference worsens
Solution Approach 1:
The patent changes the parameter of bit mapping strategy based on modulation order. For higher order modulations like 32-QAM and 128-QAM, the system adjusts the reliability weighting parameters and mapping patterns to account for increased noise susceptibility. This dynamic parameter adjustment allows the system to optimize performance for each specific modulation scheme while mitigating their inherent vulnerability to noise
3Device complexity
If conventional symbol mapping is used without reliability-based classification, then system complexity is low, but turbo coding gain is not maximized
Solution Approach 1:
The patent applies segmentation by dividing the symbol bit positions into distinct reliability categories (e.g., high-reliability positions and low-reliability positions). This segmentation allows the turbo coding algorithm to treat different bit positions differently, allocating protection bits strategically to maximize coding gain while maintaining manageable system complexity through structured classification
Data Source
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AI summary
A method for determining a bit pattern of a symbol in a wireless communication system using a cross modulation scheme. The method includes generating symbols with the cross modulation scheme, classifying positions of coding symbols by reliabilities of at least 3 classes according to an average bit error rate BER(ave) of symbols generated with the cross modulation scheme and a bit error rate BER based on transmission positions of the coding symbols in a modulation symbol during transmission of a packet with the cross modulation scheme, and determining a bit pattern such that higher-priority symbols are inserted into higher-reliability positions.