OPTIMUM TRANSMISSION RANGES IN MULTIHOP PACKET RADIO NETWORKS IN THE PRESENCE OF FADING

The evaluation of optimum transmission ranges in a packet radio networ k in a fading and shadowing environment is considered. It is shown tha t the optimal probability of transmission of each user is independent of the system model and is P-0 similar or equal to 0.271. The optimum range should be chosen so that on the average there are chi(G/b)(2/eta ) terminals closer to the transmitter than the receiver, where G is th e spread spectrum processing gain, b is the outage Signal-to-Noise Rat io threshold, eta is the power loss factor and chi depends on the syst em parameters and the propagation model The performance index is given in terms of the optimal normalized expected progress per slot, given by theta(G/b)(1/eta), where theta is proportional to the square root o f chi. A comparison with the results obtained by using deterministic p ropagation models shows, for typical values of fading and shadowing pa rameters, a reduction up to 40% of the performance index.