Diversity order optimization of multiuser multicarrier wireless systems in Nakagami fading channel

We evaluate the optimal diversity order that minimizing the bit error rate (BER) performance for a class of coded multicarrier (MC) systems over Nakagami fading channels. Diversity order optimization is performed based on the BER performance evaluated by the Gaussian approximation. This can be achieved by either applying an exclusive allocation scheme which users do not interfere with each other, or with the largest available diversity order, similar to that reported in D. Goeckel and W. Stark (1999, 2000) for Rayleigh fading channel. We then proposed new mathematical functions that relate the switching thresholds for selection of optimal diversity order (for minimum BER) to the Nakagami fading severity parameter m, signal to interference-plus-noise ratio and the degree of synchronization Ψ among users. The proposed analytical functions are useful for system designers in setting appropriate switching thresholds and analyzing system performance.