Reverse-link capacity of power-controlled CDMA systems with beamforming

In this paper, reverse-link capacity, in terms of user capacity and Erlang capacity, of a direct-sequence code-division multiple-access (DS-CDMA) system with the use of beamforming is investigated. Signal-to-interference ratio (SIR)-based power control is assumed and both transmit and receive beamforming are considered. Instead of using tedious iterative methods to evaluate user capacity, a simple closed-form capacity expression with respect to antenna gains, a target SIR, and the CDMA processing gain is derived. Numerical results indicate significant capacity improvement with beamforming. The impact of the estimation errors of arrival angles on the capacity is examined. The joint use of a RAKE receiver and beamforming is investigated and the capacity expression for CDMA systems with multiclass services is also derived.