Adaptive HARQ Target BLER for Wireless Throughput
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Solution Overview
Problem
Traditional Hybrid Automatic Repeat Request (HARQ) systems in wireless communications often fail to utilize the full capacity of HARQ retransmissions, especially under varying channel conditions, leading to suboptimal throughput.
Innovation Solution
The system dynamically adjusts the target block error rate (BLER) and modulation and coding scheme (MCS) based on real-time channel conditions to maximize throughput, allowing successful decoding on later transmission iterations and utilizing more aggressive MCS, thereby optimizing HARQ retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ systems target successful reception on the first transmission iteration, then reliability is improved, but throughput is reduced
Solution Approach 1:
The patent applies dynamics by making the target block error rate adaptive rather than static. The system dynamically adjusts the target BLER based on channel conditions, allowing it to vary between transmissions. This enables the system to sometimes target first-transmission success (for reliability) and sometimes accept higher error rates with retransmissions (for throughput), resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent changes the parameter of target block error rate from a fixed value to a variable parameter that adapts to channel conditions. By adjusting this parameter based on whether channel conditions are good or poor, the system can optimize for either reliability or throughput depending on the situation, thereby resolving the contradiction between these two opposing objectives.
2Productivity
If aggressive modulation and coding schemes are used, then throughput is improved, but error rate increases
Solution Approach 1:
The system dynamically selects modulation and coding schemes based on channel conditions and the adaptive target BLER. When channel conditions are good and target BLER is low, more aggressive MCS can be used. When channel conditions are poor or target BLER is adjusted upward, less aggressive MCS is selected. This dynamic adaptation resolves the contradiction by allowing aggressive MCS to be used selectively rather than always.
Solution Approach 2:
The patent performs preliminary determination of the target block error rate based on channel conditions before selecting the modulation and coding scheme. This preliminary action allows the system to pre-determine the appropriate level of aggressiveness for the MCS, ensuring that aggressive schemes are only selected when the adaptive target BLER permits, thereby resolving the contradiction between throughput and error rate.
3Productivity
If HARQ retransmissions are utilized more aggressively, then throughput is improved, but system complexity increases
Solution Approach 1:
The patent changes the target block error rate parameter to resolve the contradiction. By adjusting this single parameter based on channel conditions, the system can implicitly control the aggressiveness of HARQ retransmissions without needing to reconfigure multiple HARQ parameters. This simplifies the overall system complexity while still enabling aggressive HARQ utilization when beneficial for throughput.
Data Source
AI summary
Systems and methods are disclosed for improving throughput in a wireless system utilizing Hybrid Automatic Repeat Request (HARQ) retransmission. In general, prior to a HARQ-enabled transmission, one or more channel conditions for a corresponding transmit channel are obtained. Based on the one or more channel conditions, a set of target block error rates for the HARQ-enabled transmission are determined. In one embodiment, the set of target block error rates maximize throughput for the transmit channel utilizing HARQ retransmission. In another embodiment, the set of target block error rates optimize throughput and one or more additional parameters for the transmit channel utilizing HARQ retransmission.