Admission control for maximal throughput in power limited CDMA systems

Power control is a fundamental component of CDMA networks because of the interference that users cause to one another. Consequently, too many users in the system may lead to an overload whereas too few would generate an inefficient use of resources. Previous work by the authors has highlighted some fundamental properties of a CDMA system pertaining to the required power distribution when a particular terminal has reached its power limit. These properties have formed the basis for an admission control scheme which leads to an efficient use of system resources. This paper expands on this scheme and shows that optimal throughput with a fixed number of users can be achieved for a range of received power values and that this range of values is affected by the geometry of the users' location relative to the base station. In addition, there is an optimal number of users and an optimal received power ratio between them that results in maximum throughput. But when the optimal conditions can not be achieved, it is known that equal received power has good performance, and based on this, we design an admission control algorithm.