This paper tackles the challenging task of developing a simple and accurate analytical model for performance evaluation of WiMAX networks. The need for accurate and fast-computing tools is of primary importance to face complex and exhaustive dimensioning issues for this promising access technology. In this paper, we present a generic Markovian model developed for three usual scheduling policies (slot sharing fairness, throughput fairness and opportunistic scheduling) that provides closed-form expressions for all the required performance parameters instantaneously. We also present and evaluate the performance of a fourth policy, called throttling policy, that limits the maximum user throughput and makes use of the Maximum Sustained Traffic Rate (MSTR) parameter foreseen by the standard. At last, we extend these studies to multi-profile traffic patterns. The proposed models are compared in depth with realistic simulations that show their accuracy and robustness regarding the different modeling assumptions. Finally, the speed of our analytical tools allows us to carry on dimensioning studies that require several thousands of evaluations, which would not be tractable with any simulation tool.