Quantitative analyses and evaluation of various modulation techniques in effect of varying SNR and cyclic prefix over WiMAX environment

Wireless networks are generally less efficient and unpredictable compared to wired networks, which make quality of service (QoS) provisioning a bigger challenge for wireless communications. The evergreen demand for fast delivery of large volumes of data is one of the challenging task for wireless communication technology. WiMAX (Worldwide Interoperability for Microwave Access) is a wireless broadband solution that offers a rich set of features with a lot of flexibility in terms of deployment options and potential service offerings. Its main objective is to provide quality with cost effectiveness. But Delivering QoS is more challenging for mobile broadband than for fixed. The time variability and unpredictability of the channel become more acute, and complication arises from the need to hand over sessions from one cell to another as the user moves across their coverage boundaries. The wireless medium has limited bandwidth, higher packet error rate, and higher packet overheads that altogether limit the capacity of the network to offer guaranteed QoS.in this paper, we provide an overview of the cyclic prefixes (Conventional/ Turbo) and service classes that are the key functions in the MAC common part sub layer. In this thesis work, the effect of varying SNR and channel encoding is examined on to analyze and evaluate the performance of different digital modulation schemes namely BPSK, QPSK and QAM under different coging rates [1/2, 2/3, 3/4]. The impact of SNR [5, 10, 15, 20, 25] and cyclic prefixes [1/4, 1/8, 1/16, 1/32] on the performance of these said OFDMA’s digital modulation schemes under coding rate [1/2, 2/3, ¾] is observed under NS2 simulator.