Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Performance of route diversity with associated enabling algorithm

A potential benefit of multi-standard capability is the inherent diversity, owing to the independence of the communication channels associated with the different standards. Transmission of the same information across two radio channels enables correct reception in the presence of a single channel fade. The occurrence of two simultaneous channel fades is much less frequent than a single channel fade, and so this approach reduces the probability of packet loss at the expense of additional redundancy in the transmission process.

This concept has been investigated in WP6, by considering data packet transmission from a single user, across a point-to-point wireless communications link subject to multipath fading. Variable sized data packets are segmented into smaller sub-packets of an appropriate size for transmission across the communications link, with duplicate copies of each sub-packet placed in two separate queues for transmission over two independent standards. The throughput and delay performance of the proposed approach has been evaluated with stop-and-wait and go-back-N automatic repeat request (ARQ) protocols over Rayleigh channels.

Simulation results show that despite the 50% reduction in maximum useful capacity, the two-branch diversity system can offer a higher level of useful throughput for large data packet transmissions, when the probability of a transmission encountering a fade becomes significant. This is primarily due to the reduced regularity of packet retransmission owing to the much lower probability of two simultaneous channel fades compared with a single channel fade. The most significant performance enhancements are observed in the worst-case delay performance, with the two-channel system able to meet much tighter delay constraints. The greatest benefit is observed with go-back-N ARQ, as the redundancy and additional delay associated with each retransmission is much greater than with stop-and-wait ARQ.

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University of York
Heslington -
YO1 5DD York
United Kingdom
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