Influência do regime de alocação de usuários no desempenho de um sistema CDMA.

Abstract

Mobile radio systems comprise an increasing and diversified market. First generation networks, with a large number of subscribers, were deployed up to the end of the eighties and used frequency division multiple access (FDMA). The second generation, using digital systems, has been standardized and launched to increase the capacity, number of subscribers and quality of service. Some of those systems use time division multiple access (TDMA) and other code division multiple access (CDMA). The CDMA system, differently from the analog and other digital systems, has its capacity limited by the number of active users in the system, or by multiple access interference. This interference is composed of noise, other users sharing the same frequency and jamming. The objective of this work is to analyze the influence of the number of active users in the average probability of error of a CDMA system. Using this approach one expects to design mobile cellular systems in a more consistent and optimized way, avoiding the deployment of excessive radio-base stations in a certain area. This work considers a statistical allocation of users, using Queueing Theory, in order to compute the error rates and compare with the usual procedures for the design of mobile communications systems.