Providing VoIP Service over TD-SCDMA HSDPA

Providing voice over IP (VoIP) service in wireless networks is especially challenge for the tight delay requirement and the small voice packet. This paper addresses the unique issues when providing VoIP in TD-SCDMA HSDPA (time duplex division-synchronous code division multiple access high speed downlink packet access) systems. The impact of smart antenna was analyzed, which results in relative small gain of AMC (adaptive modulation and coding). An optimized scheduling and multiplexing scheme combining both time- and code-multiplexing was proposed. The VoIP performance is investigated via simulation. Results are obtained for different scheduling and multiplexing strategies, different AMC and hybrid ARQ (hybrid automatic retransmission request) settings. It was shown that the capacity of VoIP is significant higher than that of dedicated channel bearing voice.