Semi-Analytical Methodology for Assessing CDMA Forward Link Erlang Capacity

Evaluation of forward link Erlang capacity for CDMA systems has been a troublesome issue since (1) CDMA systems do not have hard limitation in traffic channels due to resource partitioning such as frequency reuse, time slot multiplexing, etc., and (2) CDMA systems allow soft handoff which makes the computation on per call or per sector basis difficult. Traditional ways to obtain the forward Erlang capacity can be too time-consuming by large scale simulations or not sufficiently accurate by table-lookup with weighted averaged number of users per cell. This paper presents a semi-analytical methodology to evaluate the Erlang capacity by iterative assessment of conditional probability distribution of traffic loading through all possible scenarios. Necessary statistics such as soft handoff and power consumption based or geometry are obtained via deployment-based simulation. A numerical evaluation is performed on the newly proposed CDMA2000 system to demonstrate the methodology.