Performance of an FH Multilevel FSK for Mobile Radio in an Interference Environment

This paper considers a frequency-hopped multilevel frequency shift keying (FH-MFSK) spread-spectrum communication system applied to cellular mobile radiotelephony. We present a mobile-to-base transmission model that allows us to study system impairments, such as interference from nonsynchronous users and adjacent frequency channels in the presence of matched tuned receiver filters. For interceli interference, the usual Gaussian approximation is used, but the variance calculation takes into account shadow fading. Power control in the mobiles, a mean path loss exponent of -3.5 and fast Rayleigh and slow Iognormal fading have been assumed. We have obtained results with mobile-to-base communication of 32 kbits/s per user in a 20 MHz (one-way) bandwidth. In an isolated cell system a bit error probability less than 10^-3can be maintained with up to 110 simultaneous users for practical average SNR ratio of 25 dB. The presence of intercell interference degrades the bit error probability enormously, and clustering of cells is required for controlling interference.