On the capacity of OFDMA 802.16 systems

In this paper, we calculate analytically the capacity of an OFDMA 802.16 system. We consider a multi-cell network and obtain the expected number of collisions for an arbitrary number of users in each interfering cell. We next obtain, for different SNR ratios corresponding to different modulation schemes, the probability of QoS degradation when collision occurs between subcarriers of two cells. We eventually calculate analytically, for a multi-service system, the proportion of symbols with poor QoS in steady-state under a given offered load. Our numerical applications show, for both adaptive and elastic traffics, how to evaluate the performance of a WiMAX system, and how to choose a modulation scheme that insures a good QoS.