Dual power control based decoding of coded and power-controlled DS/CDMA downlink signals

In this paper, we show that the traditional decoding approach employing the pilot channel based maximal ratio combining and the Viterbi or iterative decoding cannot achieve the optimal error rate performance for downlink DS/CDMA signals when a fast power control technique is applied together with a convolutional or turbo coding. Then, as an efficient method to realize a nearly optimal decoding, we propose a dual power control (DPC) technique, where the downlink power control command generated by the mobile station is used not only to adjust the base station power in the transmitter side but also to readjust the decoder input symbol power in the receiver side. Numerical results show that the DPC technique applied to the IMT-2000 W-CDMA system can improve the signal-to-interference ratio by about 0.4 dB for the block error rate of 10^-2 at the cost of a simple power re-adjustment operation.