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The purpose of this paper is to optimize a wireless link which uses forward error correction (FEC), modulation gain, and for data services, automatic repeat request (ARQ) protocols, with the aim to minimize the bandwidth required. Simulations are used to derive bit error rate values for a range of modulation and FEC code rate parameters. These parameters are optimized to maximize efficiency. We demonstrate that optimal adaptive modulation provides significant efficiency gains. We actually question the use of FEC for a wide (practical) range of signal-to-noise ratios, and demonstrate that in the case of data traffic, optimal adaptive modulation together with ARQ retransmission, in the absence of FEC, provides better efficiency, and/or QoS, than the same system with FEC. Similar results are achieved also for video, where ARQ is not used.
Date of Conference: 28 Sept.-1 Oct. 1999