Worldwide Interoperability for Microwave Access (WiMAX) (Andrews et al., 2007; and Syes and Mohammed, 2008) is a new wireless technology that provides
high throughput broadband connection over long distances based on IEEE 802.16
wireless MAN air interface standard. The driving force behind the development of the
WiMAX system has been the desire to satisfy the emerging need for high data rate
applications such as voice over IP, video conferencing, interactive gaming, and
multimedia streaming (Nuaymi, 2007; Syes and Mohammed, 2008; and Xing et al., 2008). It is designed to accommodate both fixed and mobile broadband applications.
Comparing WiMAX to Wi-Fi and 3G, the WiMAX has an improved important characteristic,
the throughput capabilities of WiMAX depends on the channel bandwidth used.
Unlike the 3G systems which have fixed channel bandwidth, WiMAX defines a
selectable channel bandwidth from 1.25 MHz to 20 MHz. In WiMAX systems. Much
research has been done for different stages such as coding stage (Changlong, 2007;
and Salmon and Olivier, 2007). Our investigations are focused on studying the
performance of WiMAX using physical layer modeling of the system over Additive White
Gaussian Noise (AWGN) channel and Rayleigh faded channel for all possible digital
modulation schemes supported. Bit Error Rate (BER) performance is compared after
including turbo coding in the system.
The paper first describes the physical layer of the WiMAX, followed by a
description of channel modeling, channel estimation scheme, turbo codes and Maximum
a-posteriori Probability (MAP) decoding. Finally before concluding, the paper
presents the simulation results. |
