Erlang capacity of voice/data CDMA systems with service requirements of blocking probability and delay constraint

In this paper, we investigate the Erlang capacity of a CDMA system supporting voice and data services with service requirements of blocking probability and delay. We define the delay confidence defined as the probability that a new data call is accepted within the maximum tolerable delay without being blocked. In this case, the Erlang capacity is confined not only by the required blocking probability of voice call but also by the required delay confidence of data call. For the performance analysis, we develop a two-dimensional Markov model, and we derive the CDF of delay and subsequent relation for the delay requirement. Further we present a numerical procedure to analyze the Erlang capacity under a given blocking probability and delay confidence. As a result, it is necessary to make a balance between the Erlang capacity with respect to the blocking probability of voice call and that with respect to the delay confidence of data call so as to accommodate the more Erlang capacity.