Site independent diversity transmit power control for inter-cell site diversity in W-CDMA forward link
Akihito Morimoto, Kenichi Higuchi, Mamoru Sawahashi · 2002
This paper proposes a new fast transmit power control algorithm for forward link inter-cell site diversity, called site independent diversity transmit power control (hereafter SIDTPC) and compares the effect of decreasing the total transmit signal energy per bit-to-background noise power spectrum density ratio (E/sub b//N/sub 0/) of all cell sites for three methods: SIDTPC, site selection diversity transit power control (SSDT), and conventional TPC during inter-cell site diversity (hereafter CTPC) in the W-CDMA forward link. The SIDTPC method differs from SSDT in that each cell site transmits a dedicated physical channel (DPCH) with different transmit power, which is adaptively weighted according to the path loss between each cell site and a mobile station (MS), that is to say, with larger (smaller) transmit power for the cell having the smaller (larger) path loss, resulting in a decreased total transmit power similar to the SSDT method, while maintaining a superior feature which enables SIDTPC to be less sensitive to the reception errors of the control bits sent via the reverse link. Simulation results demonstrated that when the traffic ratio of voice service to data service is 1:1, the required total average transmit E/sub b//N/sub 0/, at the average block error rate (BLER) of 10/sup -2/ for 50% of MSs using the SIDTPC method is decreased by approximately 0.4 (0.5) dB and 2.0 (0.2) dB compared to those with the CTPC and SSDT methods, respectively, for Doppler frequency, f/sub D/, of 5 (80) Hz.