Erlang capacity of a CDMA cellular system with multirate sources

The capacity in a CDMA system is defined as the maximum offered traffic load that satisfies the admission criterion 99% of the time. In this paper, the capacity is calculated using a novel approach that can accommodate different traffic sources with variable transmission bit rates. In this approach, each source is modelled using a continuous-time Markov process. The Markov processes for all sources are superimposed to obtain another Markov process which is then used to yield the capacity or blocking probability. The analysis is done for networks with both homogeneous (one class) and heterogeneous (multiple classes) traffic sources. Imperfection in power control is also considered. We show that the proposed model can capture the traffic burstiness and hence yields more realistic results.