Fast Retransmission Indicator Bypasses HARQ Processing Latency
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Solution Overview
Problem
Existing LTE systems face challenges in reducing packet data latency and improving radio resource efficiency due to the delays in uplink HARQ retransmission processes, particularly in scenarios requiring fast and efficient retransmissions.
Innovation Solution
Implementing a Fast Retransmission Indicator (FRI) to trigger retransmissions using the same redundancy version and transmission parameters as the previous transmission, thereby bypassing the need for reprocessing blocks in the transmission chain, allowing for faster retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HARQ retransmission process is used, then transmission reliability is ensured through proper acknowledgment and retransmission, but packet data latency increases due to processing delays in the retransmission chain
Solution Approach 1:
The patent applies preliminary action by pre-processing and buffering data packets at the UE before actual transmission. When a retransmission is triggered by FRI, the pre-processed packet is immediately transmitted without going through the complete reprocessing chain, thus reducing latency while maintaining reliability through the buffered ready-to-send packet
Solution Approach 2:
The patent extracts the time-consuming reprocessing blocks from the fast retransmission path. By identifying and removing unnecessary processing steps for retransmissions (triggered by FRI), the system achieves faster retransmission while the extracted processing is performed only for initial transmissions, thus resolving the contradiction between speed and reliability
2Manufacturing precision
If complete reprocessing is performed for each retransmission, then transmission accuracy is improved, but processing time and system latency increase
Solution Approach 1:
The patent applies partial action by performing complete processing only for initial transmissions and partial processing for retransmissions. When FRI triggers a retransmission, the UE transmits the buffered packet with minimal processing, achieving sufficient accuracy for retransmission without the full processing overhead, thus reducing processing time while maintaining adequate transmission accuracy
3Loss of time
If fast retransmission is implemented by bypassing processing blocks, then latency is reduced, but transmission reliability may be compromised
Solution Approach 1:
The patent ensures reliability in fast retransmission by performing preliminary actions during initial transmission - the UE pre-processes the packet, performs coding, and buffers it in readiness. This preliminary preparation ensures that when FRI triggers a fast retransmission, the buffered packet is already in a reliable, transmission-ready state, eliminating the reliability compromise that would otherwise result from bypassing processing blocks
Data Source
AI summary
The invention relates to an improved transmission protocol for uplink data packet transmission in a communication system. A receiver of a user equipment receives a Fast Retransmission Indicator, referred to as FRI. The FRI indicates whether or not a base station requests a retransmission of a previously transmitted data packet. A transmitter of the user equipment retransmits the data packet using the same redundancy version as already used for the previous transmission of the data packet.