The wireless communications evolved considerably in the last few years. This fact encouraged the deployment of several systems or cellular networks in multi technological environment. Worldwide Interoperability for Microwave Access (WiMax) is an emerging standard for next generation wireless communication system with high data rate and broacoverage. In this paper, we present the simulation of a digital communication system based on the specifications of IEEE 802.16d standard (WiMax) in order to evaluate the performance of this system. WiMax standard allows a good transmission, considering relatively high SNRs using RS-CC channel encoder. Considering the UTTCM encoder with iterative decoding, the aim is to decrease the SNR (reduce the transmission power) and thus improve the performance of the transmission system. This work focuses on the performance comparison of the standard WiMax system and WiMax system using UTTCM as channel coding. The simulation results have shown that, with lower decoding complexity, the UTTCM-based WiMax system achieved better performance