PERFORMANCE ANALYSIS OF FIXED AND MOBILE WIMAX SYSTEMS

Abstract

The common feature of the next generation of wireless communications technologies (or 4G ) will be the convergence of different wireless networks with multimedia services such as speech, audio, video, image, Internet services, and data at high data rates and with high mobility, high capacity and high QoS. There are many techniques that fulfill these requirements. One of the most important technique is Orthogonal Frequency Division Multiplexing (OFDM) . OFDM has recently gained a lot of attention and is a potential candidate for 4G wireless systems because it promises data rates up to one Gbps or less under stationary conditions and up to about 100 Mbps under vehicular conditions and it has robustness against multipath fading channels effects. A variation of OFDM is Multi-Carrier Code Division Multiple Access (MC-CDMA) which is an OFDM technique where the individual data symbols are spread using a spreading code in the frequency domain. The spreading code associated with MC-CDMA provides multiple access technique as well as interference suppression. WiMAX (Worldwide Interoperability for Microwave Access) is OFDM-based technology that supports point to multi-point (PMP) Broadband Wireless Access (BWA) for the next generation radio access. Main application (fixed and mobile) of WiMAX today is for MAN/WAN base stations and link stations. It delivers the maximum range (50 km) and higher data rates (up to 75 Mbps) than Wi-Fi. WiMAX has been implemented depending on IEEE 802.16 standard which was designed by Institute of Electrical and Electronic Engineers (IEEE). This thesis aims to analyze and simulate a MC-CDMA system to be used in WiMAX instead of OFDM system. A MATLAB code had been written to simulate both Fixed WiMAX (IEEE 802.16d) and Mobile WiMAX (IEEE 802.16e). The analysis part includes a comparison between them in performance evaluation. The simulation results include the performance analysis based on bit error rate (BER) versus bit energy to noise rate (Eb/No ) plots and spectral efficiency of different modulation and channel coding schemes according to the standard IEEE 802.16. The results show that MC-CDMA outperforms OFDM in WiMAX system and enhances the performance more when spreading factor increases.