UMTS Air Interface Voice/Data Capacity - Part 1: Reverse Link Analysis
01 January 2001
Universal Mobile Telecommunication System (UMTS) is a 3rd generation wireless communication system based on Wideband CDMA (WCDMA) technologies. Compared to the 2nd Generation (2G) systems, UMTS can offer much larger capacity for voice service and support high-speed data for internet access and multimedia services. In this paper, we evaluate the air interface capacity for voice, data, integrated voice and data services in UMTS. We present our analytical and simulation models for the reverse link only. The analysis on the forward link will be presented in a sequential paper. In our analytical mode, we consider different varying factors in a CDMA system, such as the interference level, power control errors, soft handoff, required signal-to-interference ratio for different rates, etc. We propose a new approach to model the intercell interference. We use different approximation methods to calculate capacity based on voice and/or data traffic loading. Finally, we derive the Erlang capacity expression for a single type of traffic and mixed types of traffic as well. We also developed a static system level simulator to evaluate capacity and coverage for UMTS. We compare our analytical results with simulations and show that our analytical approach has a very good match with simulations.