Combined downlink power control and joint multicode receivers for downlink transmissions in high speed UMTS

Abstract

In this paper, we propose to combine the gains of a downlink power control and a joint multicode detection, for a HSDPA link. We propose an algorithm, which controls both the transmitted code powers and the joint multicode receiver filter coefficients. The proposed algorithm is iterative. At each iteration, first, the receiver filter coefficients of the multicode user are updated to reduce the inter-code interferences and then, the transmitted code powers are updated. So that, each spreading code of the multicode scheme creates the minimum possible interference to others while satisfying the quality of service requirement. This algorithm has as main goals to decrease inter-code interference and to increase the system capacity. Simulation is used to show the convergence of the proposed algorithm to a fixed point power vector where the multicode user satisfies its signal-to-interference ratio (SIR) target on each code