Browsing by Author "Ismail, Moses"

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    Improvement of the throughput of arq protocols in rayleigh fading environments
    (University of Dar Es Salaam, 2013) Ismail, Moses
    Throughput is an essential quantity for wireless data communication systems and there is always a need to ensure that a system throughput is made as high as possible. Although throughput depends on a number of variables, error probability being dictated by the environment through which the signal propagates on its way to destination has stood out as the most determinant. In Rayleigh fading environments the error probability is very high that it significantly affects the throughput of communication systems operating over such environments. Using the Stop and Wait (SW) Automatic Repeat Query/Request (ARQ) scheme, this dissertation has analyzed the throughput improvement scheme for a communication system operating in Rayleigh fading environment and which uses diversity and Forward Error Correction (FEC) as the fading mitigation measures. Results show that diversity improves throughput significantly. For example, at SNR of 17dB, diversity order two and three improved throughput to 3982 bps (42%) and 3982 bps (48%) respectively from 2808 bps for a fading channel without diversity. When FEC was used throughput improved to 4114 bps (46.5%) and 4589 bps (63.4%) for one error and two errors correction respectively, from 2808 bps when no error was corrected. When FEC and diversity were used together throughput improved further to 4826 bps when diversity order two was used along with one error correcting code. In this case, it has been clearly shown that diversity and FEC improve throughput.