Spectrum efficiency optimization in a cellular packet data communication system

A simulation model of multiple co-channel interferers in a cellular communication system, for downlink traffic using non-coherent frequency shift keying modulation, is developed and used to investigate the bit error rate (BER) and block error rate (BKER) of the packet data traffic as a function of the number, n_I, of interferers. It is found that for large n_I the interference signal can be modeled as white Gaussian noise of the same power spectral density (PSD) value. The results are used to determine the spectrum efficiency, E_s, for different system configurations. The optimal value, K _opt of the cluster size is studied. With no fading or very slow Rayleigh fading, K_opt is small, typically less than 4. However, K_opt increases with the Doppler frequency. The use of FEC tends to lower K_opt but does not necessarily improve E _s