IP-based transport of voice traffic in the UMTS radio access network: Analytical study and empirical validation

In this paper, we investigate the IP protocol as a transport option for the user traffic in the UMTS Terrestrial Radio Access Network (UTRAN), where stringent delay bounds are to be met for both real-time and non real-time traffic. We focus on real-time voice traffic and present an analytical model for the multiplexing and transport of voice channels in the UTRAN using IP. The novelty of our model is that it analytically includes and quantifies the performance of the timer used in multiplexing arriving Frame Protocol (FP) frames into larger IP packets. We then validate our work through empirical results on a test-bed emulating the UTRAN transport functionalities. We show the trade-offs between performance, in terms of delay and link utilization, and quantify optimal values for the timer as well as the number of FP frames per IP packet for a given output link capacity.