Performance of CSMA protocols in fading mobile radio environments

A previous publication on application of CSMA protocols in mobile radio data networks by Jabbar and Gardiner (1987) has treated the non-persist protocol in ideally fade-free channels. The present paper reports an extension of this earlier research to cover one-persist and p-persist protocols in simulated fading conditions as encountered by moving terminals in multipath radio propagation environments. The simulation technique employed follows the general method of earlier work based on a purpose-built discrete event simulator written in FORTRAN 77. Results focus on message delay and channel throughput in a channel assumed to support 20 kbits/sec transmission at 850 MHz carrying packets of 1000 bits length. Non-persist CSMA in a fade-free environment is compared with the same protocol operating under fading conditions. For the latter case, urban and motorway type conditions are assumed with average vehicle speeds of 40 mph and 80 mph respectively in a median field strength which gives a 30 dB signal-to-noise ratio at the receiver input