Effect of timing adjust algorithms on Iub link capacity for voice traffic in W-CDMA systems

The goal of the timing adjust algorithm in UMTS networks is to adjust the arrival times of downlink frames from the RNC (radio network controller) to the node B so that the frames arrive within a predefined time window before the scheduled transmission time of the frame. The algorithm provides feedback from the node B to the RNC, causing a delay or an advance of the next transmitted frame based on the arrival time of the current frame. We present a study of the effect of the timing adjust algorithms in UMTS networks on the Iub link capacity for voice traffic. Through simulation, we present estimates of call carrying capacities and statistical multiplexing gain on Iub links of different capacities. We also present an analytical framework to explain the impact of the timing adjust algorithm on the statistics of Iub delay for voice traffic.