Cross-Layer Rate Aware Network Coding for Wireless Communication Systems

Fiona Vi Nguyen

Abstract


Network Coding (NC) is a relatively new research area that has been demonstrated to improve network performance by utilising the concept of packet combinations to increase data throughput. The aim of this project is to reduce the delivery time (in seconds) of messages to wireless users using instantly decodable network coding (IDNC) with physical layer rate awareness. Previous work involving IDNC systems focused on optimising parameters from an upper layer network perspective and reduced physical layer influences to simple erasure channel probabilities. This simplification is an unrealistic representation of empirical channel conditions. These conditions result in different transmission rates between a base station (BS) and the users in a network. Adapting a cross layer NC scheme, which considers the heterogeneity of transmission rates, is a more realistic approach to the problem. This is currently a very limited area of research. The project was divided into three phases, each phase comprising of the following stages: theoretical scoping, algorithm development, simulation, and analysis. Phase 1 was the development of a point-to-multipoint rate adapted IDNC system utilising a single-layer maximum weighted clique selection policy. Phase 2 was the implementation of a rate adapted multi-layer scheme based on the concept of prioritising decisive users who will most likely extend the overall completion time. Phase 3 was the application of the best performing algorithm to a multipoint-to-multipoint situation involving two coordinated base stations. Phase 1 results showed the proposed algorithm’s mean completion time improved by approximately 71.76% (for several users and packets) when compared to an equivalent simple selection scheme which did not combine packets for transmission. Phase 2 results found that the multi-layer rate aware scheme performed 10.22% worse than the Phase 1’s single-layer scheme. Phase 3 was the application of the single-layer scheme to a Multi-Base Station (MBS) scenario which saw an improvement 50.34% when compared to a scheme which did not combine packets. The development of an effective rate adapted single-layer heuristic solution (applied to a MBS scenario as well) is the major contribution to the research area.

Keywords


Network Coding; Rate Aware; Cross-Layer

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