UMTS air interface voice/data capacity-part 1: reverse link analysis

For pt.2 see ibid., p.2730-4. Universal Mobile Telecommunication System (UMTS) can offer large voice capacity for voice service and support high-speed data for Internet access and multimedia services. We evaluate the air interface capacity for voice, data and integrated voice and data services in UMTS. We present our analytical and simulation models for the reverse link only; the forward link analysis is presented in part 2. In our analytical model, different varying factors in a CDMA system are considered, 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 inter-cell interference under multiple cell condition. Furthermore, we apply different approximation methods to calculate the capacity based on voice and/or data traffic loading. Finally, we derive close form expressions of Erlang capacity for a single type of traffic and mixed types of traffic. We also develop a static system level simulator to evaluate capacity and coverage for UMTS. By comparing our analytical results with simulations, we show that our analytical approach has a very good match with simulations.