Multiple Incremental Redundancy Retransmission Code Rate Adaptation
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in retransmission schemes, particularly in adapting code rates to achieve optimal spectral efficiency and throughput, due to limitations in channel state information feedback and retransmission strategies, leading to suboptimal performance and increased latency.
Innovation Solution
A multiple incremental redundancy retransmission scheme is implemented, where the transmitter device initially sends a message with an overestimated code rate, and upon feedback indicating decoding failures, subsequent retransmissions include incrementally fewer bits to lower the effective code rate, allowing dynamic adaptation based on feedback to approach the optimal code rate for the channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed code rate is used in initial transmission, then transmission simplicity is maintained, but spectral efficiency deteriorates due to inability to adapt to actual channel conditions
Solution Approach 1:
The code rate is made dynamic through incremental redundancy retransmissions. The transmitter sends additional parity bits in subsequent transmissions based on feedback about decoding success, allowing the effective code rate to adapt from an initial overestimated value to a final optimal value that matches channel conditions.
Solution Approach 2:
The code rate parameter is changed incrementally across multiple transmissions. Each retransmission adds redundancy bits to modify the effective code rate, transitioning from an initial code rate that assumes worse channel conditions to a final code rate optimized for actual channel quality.
2Reliability
If retransmissions are sent to ensure decoding success, then reliability is improved, but latency increases due to multiple transmission rounds
Solution Approach 1:
The system implements feedback-based retransmission where the receiver sends ACK/NACK signals to indicate decoding success or failure. This feedback mechanism allows the transmitter to send retransmissions only when necessary, improving reliability while minimizing unnecessary delays from excessive retransmissions.
Solution Approach 2:
The initial transmission uses an overestimated code rate (excessive redundancy) to ensure decoding success under worst-case assumptions. Subsequent retransmissions progressively reduce redundancy as feedback confirms successful decoding, eliminating excessive actions and reducing latency.
3Productivity
If channel state information feedback is enhanced for accurate code rate selection, then spectral efficiency is improved, but system complexity and overhead increase
Solution Approach 1:
The system uses simple ACK/NACK feedback from the receiver to automatically determine when retransmissions are needed and what code rate to use. This self-service mechanism allows accurate code rate adaptation without requiring complex channel state information feedback or sophisticated transmitter-side channel estimation.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a transmitter device may transmit, to a receiver device, an initial message associated with a communication using a first code rate. The transmitter device may receive, from the receiver device, first feedback information indicating that the communication was not successfully decoded by the receiver device. The transmitter device may transmit, to the receiver device based at least in part on the reception of the first feedback information, one or more retransmissions associated with the communication including a first retransmission, wherein the first retransmission includes a first number of bits to lower an effective code rate of the communication to a second code rate. The transmitter device may receive, from the receiver device, second feedback information indicating that the communication was successfully decoded by the receiver device. Numerous other aspects are described.