Optimum parameters for maximum throughput of FHMA system with multilevel FSK

Abstract

The authors optimize system parameters including modulation order M, diversity order L, and traffic density lambda to maximize the throughput of frequency-hopping-multiple-access networks with multilevel frequency-shift keying. It is shown that optimal lambda is close to ln 2 with the exception that optimal lambda = 1 for the erasures coding channel with M = 2. For the erasures coding channel, optimum L is also derived, and for the hard-decision coding channel, optimum L is numerically searched. For the region of M < 64, the erasures coding channel achieves higher throughput than the hard-decision coding channel, and for the region of M > 64, the hard-decision coding channel achieves slightly higher throughput than the erasures coding channel. While the maximum throughput for the hard-decision coding channel monotonously increases as M increases, the maximum throughput for the erasures coding channel shows a local increase at M = 2, and it is significantly higher than that for the hard-decision coding channel with M = 2. Tradeoffs between system parameters to achieve the maximum throughput under a fixed bandwidth constraint are also presented. It is shown that the optimal set for (M, L, N (= number of available frequencies)) is approximately (G, log(2) G, G) for both coding channels, where G is the total system bandwidth expansion normalized by bit rate.