In this paper, we study the capacity of broadband wireless OFDMA-based WiMAX systems, in the presence of both constant-bit-rate streaming traffic as well as elastic one, under a dynamic configuration wherein users come to the system and leave it after a finite duration. This duration is function of the resources they obtain for the case of elastic flows; it is not for voice ones. Using Markovian analysis, we calculate several performance measures, such as the blocking probability and mean transfer time, using exact and approximate, quasi-stationary-based, solutions. We eventually show numerically the performance of such a system under different admission figures.