Adaptive frequency-hopping for TDMA/CDMA

This work considers asynchronous DS-CDMA systems with RAKE receivers and one stage of parallel interference cancellation. A general method based on the concept of spherically symmetric signals, is presented for the evaluation of the average probability of error of uncoded time-division multiple-access/code-division multiple-access (TDMA/CDMA) with and without slow-frequency-hopping signals, over a multipath Rayleigh fading channel (which models indoor and outdoor vehicular radio propagation). We analyse QPSK modulation with coherent demodulation and multipath (frequency) diversity by maximal ratio combining (MRC). Power-control, adaptive slow-frequency-hopping (SFH) and parallel interference cancellation are employed for improving the bit error rate (BER) performance. It is found that the scheme with SFH is always superior, and interference cancellation provides the highest BER improvement