Hybrid error control techniques to improve data communication performance for noisy channels have been extensively studied. However, a growing concern in communication system design is the impact of delay due to retransmissions and/or delay-prone technologies on system performance. Previous analyses have not considered various delay aspects of a hybrid error control system. Efficient error control techniques which are able to provide improved coding gain and throughput by promptly matching the error correction coding capability with the changing channel conditions have yet to be developed and investigated.
In this thesis, delay-related performance characteristics are investigated for asynchronous time division multiplexing links. Two different methods based on an imbedded Markov chain model are developed and applied to the system with a noisy feedback channel, yielding analytical expressions for the buffer occupancy and the block delay. A recursive expression for packet loss probability for systems with a finite transmitter buffer is obtained.
The concept of delay-limited error control coding is introduced for real-time communications. Performance improvement by truncation of a type-II hybrid-ARQ protocol with one retransmission is investigated in detail. It is shown that the truncated protocol has a bounded delay and bounded queue length under typical communication traffic conditions. The error performance of the truncated protocol is further analyzed for various mobile fading channels.
Matched-rate hybrid error control coding for both adaptive and non-adaptive cases is also studied. A new adaptive error control protocol using Reed-Solomon codes is proposed. The protocol uses novel feedback transmissions to achieve faster estimation of channel states. Numerical optimization is carried out by introducing overall throughput and modified throughput as efficiency criteria. Based on channel bit error rate measurement, optimum overall throughput is obtained with minimum implementation complexity.
Our general conclusions are: (1) Both delay and packet loss can be greatly reduced by incorporating a Reed-Solomon code into the data-link protocol for noisy channels. (2) The truncated hybrid error control protocol can provide coding gain improvement and reduced delay over the conventional (untruncated) protocol. (3) Throughput efficiency of a type-I or type-II hybrid-ARQ protocol can be significantly improved by using the proposed matched-rate error control techniques. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/9609 |
| Date | 05 July 2018 |
| Creators | Yang, Qing |
| Contributors | Bhargava, Vijay K. |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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