Selective H-ARQ Retransmission for Multi-Hop VoIP Delay
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Solution Overview
Problem
In wireless relay networks, the conventional Hybrid Automatic Repeat Request (H-ARQ) protocol introduces significant delay due to retransmissions, which is particularly problematic for delay-sensitive services like VoIP, as it can exceed stringent delay requirements and degrade service quality.
Innovation Solution
Limiting retransmissions to the first link between the mobile node and the relay node, while using more robust link adaptation and routing techniques on subsequent links to ensure reliable communication, thereby reducing overall delay and enhancing service quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If H-ARQ retransmissions are applied on each hop in multi-hop relay networks, then communication reliability is improved, but transmission delay increases significantly
Solution Approach 1:
The patent segments the multi-hop communication path into distinct hops, and applies different error handling strategies to each segment. Specifically, H-ARQ is applied selectively on certain hops while other hops use alternative error handling mechanisms, thereby reducing the cumulative delay impact while maintaining overall reliability.
Solution Approach 2:
The patent implements local quality by applying H-ARQ retransmissions only on specific hops where it is most beneficial, rather than uniformly across all hops. This selective application optimizes the balance between reliability and delay by concentrating retransmission resources on critical link segments.
2Reliability
If H-ARQ retransmissions are used on multiple hops, then packet delivery reliability is enhanced, but end-to-end delay accumulates and exceeds service requirements
Solution Approach 1:
The patent applies partial action by implementing H-ARQ on only a subset of hops rather than all hops. This partial application is sufficient to achieve the required packet delivery reliability while avoiding the excessive delay that would result from applying retransmissions on every hop in the multi-hop path.
Solution Approach 2:
The patent changes the parameter of retransmission application from a uniform across-all-hops approach to a selective per-hop approach. By modifying which hops receive H-ARQ treatment, the system achieves the desired reliability while controlling the end-to-end delay within service requirements.
3Reliability
If conventional H-ARQ protocol is applied in relay networks, then error control is improved, but delay-sensitive services like VoIP cannot meet stringent delay requirements
Solution Approach 1:
The patent segments the error control mechanism by applying H-ARQ selectively on specific hops rather than uniformly across the entire communication path. This segmentation allows delay-sensitive services to maintain adequate error control on critical hops while avoiding excessive delay accumulation that would degrade service quality.
Solution Approach 2:
The patent implements local quality by tailoring the error control strategy to specific hop characteristics. H-ARQ is applied on hops where it provides the most benefit for maintaining service quality, while other hops use alternative error handling approaches that introduce minimal delay, thereby preserving overall service quality for delay-sensitive applications.
Data Source
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AI summary
Minimization of delay due to automatic repeat requests in a multi-hop communication system can be accomplished to optimize the performance of delay-constrained applications such as voice over internet protocol (VoIP). The protocol described with relation to such embodiments can reduce the possible retransmissions to the first hop (the hop connecting a mobile node to a relay node). Thus, certain embodiments of the present invention can protect the most error-prone link while reducing the overall delay experienced by the user.