User capacity of a power controlled CDMA system with multiple base stations

Abstract

The user capacity of the uplink of a multiple cell synchronous CDMA system is analyzed along with power and channel allocation. For the most part, attention is focused on the situation when the signature sequences are chosen from an orthogonal sequence set. The user capacity of the system is the maximum number of users per unit processing gain admissible in the system such that each user has its quality of service (QoS) requirement (expressed in terms of its desired signal-to-interference ratio) met. The user capacity depends on the path gains of the users to the base stations and the comparison of the user capacity per unit processing gain with the maximum number of admissible users in a single channel system allows us to describe (in terms of the path gains) scenarios when the user capacity of the system can be increased by having more processing gain. We conclude by conjecturing the user capacity region when the signature sequences are not constrained and the base station estimates the users' symbols with matched filter and linear MMSE receiver structures.