Quality of service of Internet applications over the UMTS radio interface

The continuing evolution of exponential growth of the Internet market and growing demand of data services in fixed networks is also expected for mobile users. Universal Mobile Telecommunications System (UMTS) as the 3rd generation mobile system is designed to provide high bit data rates to the user. The mobile Internet access will play a key role to ensure success of UMTS introduction. Typical Internet applications are running on a Transmission Control Protocol/Internet Protocol (TCP/IP) stack which should ensure a reliable end-to-end communication in systems with limited quality of service guarantee. In contrast, most protocols of radio access systems will grant traffic contracts. This raises the question if the benefits of TCP might be a drawback for the overall performance of the radio interface with its own quality of service management mechanisms. The aim of this paper is to examine the interaction between TCP and the UMTS Radio Link Control (RLC) protocol. Of special concern is the interaction of TCP retransmissions with the RLC Automatic Repeat Request (ARQ) mechanisms. Simulations have been performed to evaluate the performance of the implemented protocol stack with and without TCP. Simulation results of quality of service parameters like delay and packet throughput depict the performance of mobile Internet access over UMTS.