Outage probability in mobile radio systems

Abstract

Outage probability calculations are presented for the analogue land mobile radio situation where in order to obtain satisfactory radio reception both a sufficient CNR and CIR need to be achieved simultaneously. Such calculations can be used in the design and analysis of mobile radio systems and may be particularly useful for investigating the effects of cochannel interference in cellular systems. The outage probability expressions are derived using previously reported statistical descriptions of mobile radio propagation. Attention is generally focussed on situations where signals suffer Rayleigh fading and/or lognormal shadowing. However calculations for Nakagami-m, Rice and Weibull fading are also considered. The rapid growth in cellular mobile radio systems has stimulated the development of outage probability calculations for multiple interferer situations. Previously, while single interferer situations had been treated exactly, multiple interferers had been treated by approximate methods. In this thesis exact multiple interferer outage probability expressions are presented for the Rayleigh fading and the joint 'fading and shadowing' (Suzuki) situations. Similar expressions, but for more limited cases, are also presented for lognormal and Nakagami-m statistics. Using results from these expressions the accuracies of several approximate outage probability methods are assessed. The exact outage probability expressions for multiple Suzuki interferer situations are closely related to those for multiple Rayleigh interferer situations. Indeed, the exact analytic expressions for Rayleigh statistics form an integral part of the corresponding outage probability expressions for Suzuki statistics. These latter expressions can be readily evaluated using Gauss-Hermite numerical integration. In order to demonstrate the use of such calculations for mobile radio system analysis several theoretical examples are presented. Outage probability calculations for multiple interferer systems which employ diversity reception as a means of improving communications reliability are considered. Similarly, the extension of outage probability concepts to digital systems is briefly outlined.