GPRS Link Adaptation via Block Error Rate Metrics
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Solution Overview
Problem
Link adaptation in General Packet Radio Service (GPRS) networks often neglects the debilitating effects of high block error rates on higher layer protocols, leading to inefficient airlink performance and user experience issues due to variable delay and resource wastage.
Innovation Solution
A link adaptation methodology that determines the appropriate coding scheme based on measurements of block error rates and conditional channel quality metrics, such as bit error rate, to select the strongest coding scheme that balances throughput and error rate, thereby mitigating the impact of high block error rates on higher layer protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If link adaptation selects coding scheme based on maximizing throughput alone, then airlink efficiency is improved, but block error rates increase causing retransmissions and protocol performance degradation
Solution Approach 1:
The patent changes the selection criteria parameter from throughput-only to a composite metric that includes both throughput and block error rate. The link adaptation algorithm now selects coding schemes by evaluating both parameters simultaneously, preventing the degradation of protocol performance while maintaining high airlink efficiency.
2Speed
If high rate coding schemes (e.g., CS-4) are used to maximize throughput, then data transmission speed is improved, but error correction capability deteriorates leading to undetected or uncorrected errors
Solution Approach 1:
The patent implements dynamic coding scheme selection that adapts to current channel conditions. Instead of using a fixed high-rate coding scheme, the system dynamically adjusts the coding scheme based on real-time measurements of block error rates and channel quality, switching between strong error correction (CS-1) and high speed (CS-4) as needed.
Solution Approach 2:
The patent introduces feedback mechanisms where the system monitors block error rates and channel quality metrics, then uses this feedback to adjust coding scheme selection. This closed-loop approach ensures that high-rate schemes are only used when channel conditions permit, preventing error accumulation while maximizing throughput when possible.
Data Source
AI summary
In one embodiment of the method of adaptively selecting an airlink coding scheme in a telecommunications network, a coding scheme operating region is determined based on a currently used coding scheme and measurements representative of a block error rate. A block error coding scheme is determined based on the determined coding scheme operating region. In another embodiment of the method of adaptively selecting an airlink coding scheme in a telecommunications network, a first coding scheme is determined based on measurements representative of one or more conditional channel quality metrics, and a second coding scheme is determined based on measurements representative of a block error rate. One of the first and second coding schemes is selected as the coding scheme.