Evaluation de la capacite en Erlangs d'un reseau CDMA non-homogene pour le lien montant.

摘要

The current IS-95[4] standard of cellular telecommunication, and the future CDMA 2000[5] standard both use spectral spreading as modulation and multiple access means. A CDMA network is interference-limited rather than bandwidth-limited, and the Erlang Capacity is calculated according to the probability of blocking by the network, i.e. the probability that a new mobile is denied access to the network. The traditional approaches to calculate the capacity of such a network were either deterministic or assumed a uniform geographical distribution of the mobiles.;In this thesis, various approaches are presented making it analytically possible to obtain an evaluation of the Erlang capacity of the network. A probabilistic approach was adopted to model the various parameters involved. The computations are based on the first two moments of the various random variables according to two basic distinct approximations: namely Normal and Lognormal. A criterion on the blocking probability has been found to yield the best results, allowing to choose between the normal and lognormal approximations.;A systematic comparison of the performance of the network under various modeling conditions and an analysis of the sensitivity of the capacity with respect to various parameters has been carried out. The geographical distribution of the mobiles, the precision of the power-control scheme, the influence of the other cells in the network as well as the propagation conditions were taken into account and their influence on the capacity analyzed. Finally, a formula yielding the cellular capacity of a heterogeneous network is introduced.