Uplink Packet Delay Optimization in Cooperative Relay Networks
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Solution Overview
Problem
In relay-enabled cellular networks, packet delay in the uplink transmission is increased due to error checking procedures and lack of cooperative communication among relay nodes, leading to quality degradation in real-time applications and increased latency in non-real-time services.
Innovation Solution
The implementation of novel uplink Hybrid Automatic Repeat Request (HARQ) schemes for single-hop/multi-hop cooperative communication links, where relay nodes transmit packets even with errors and measure channel quality to adjust transmission power or weighting, enabling end-to-end HARQ mechanisms between user equipment and eNBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relay nodes perform error checking procedures before forwarding packets, then packet transmission reliability is improved, but packet delay increases
Solution Approach 1:
The relay node performs partial error checking (CRC check) without waiting for complete error-free verification before forwarding. It forwards the packet with attached channel quality measurement even if errors are detected, allowing the destination to perform error correction using cooperative diversity, thus reducing delay while maintaining reliability
Solution Approach 2:
The relay node performs preliminary actions by measuring channel quality and attaching this information to the packet before forwarding. It also proactively forwards packets with errors rather than waiting for retransmission, enabling the destination to prepare for potential error correction in advance
2Loss of time
If relay nodes transmit packets with errors to reduce delay, then packet delay is reduced, but transmission reliability deteriorates
Solution Approach 1:
The relay node attaches channel quality measurements (feedback information) to the forwarded packet. This feedback enables the destination node to adaptively combine multiple received versions of the packet with appropriate weighting based on channel conditions, thereby maintaining high reliability even when forwarding packets with errors
Solution Approach 2:
The system uses excessive error correction capability by allowing packets with errors to be forwarded and relying on the destination's cooperative diversity combining and error correction mechanisms to recover the original data, thus achieving both low delay and high reliability
3Reliability
If relay nodes perform demodulation and decoding operations, then link quality is improved, but processing time and complexity increase
Solution Approach 1:
The relay node performs partial processing (demodulation and channel quality measurement) but skips the time-consuming decoding operation. It forwards the packet with attached measurement information, allowing the destination to perform the final decoding, thus improving link quality awareness without incurring full processing time penalty
Solution Approach 2:
The processing tasks are segmented between relay node and destination node. The relay node handles demodulation and channel measurement, while the destination node performs decoding and final error correction. This segmentation allows the relay to quickly prepare packets for forwarding without the overhead of complete processing
Data Source
AI summary
A method for communication in a wireless network is provided. The method includes a relay node receiving a data packet and determining whether to transmit the packet without performing error checking.