PERFORMANCE ANALYSIS OF FREQUENCY-HOPPED SPREAD-SPECTRUM PACKET RADIO NETWORKS PART II: UNSLOTTED MULTIPLE-ACCESS

Abstract

This paper is concerned with the performance analysis of unslotted frequency-hopped spread spectrum packet radio networks with Reed-Solomon forward error control coding. The following different network alternatives are analyzed in a unified manner (i) random/one-coincidence frequency hopping patterns, (ii) one/several code symbols per dwell interval, (iii) independent/dependent packet arrival processes, (iv) fixed/variable length packets. Joint probability generating functions for the pair-wise hit patterns and the effective multiple-access interference vector are determined for the different alternatives. Closed form formulae and expressions for packet capture probabilities are readily obtained from these generating functions. A direct proof is given that in the case of single symbol/dwell packets symbol errors, are asymptotically independent. Numerical results indicate that the unslotted networks outperform the corresponding slotted ones at low to moderate traffic levels, and the difference between the two networks is diminishing when the number of frequency bins is large.