WiMAX OFDM Adaptive Modulation with Broadband Wireless Technology HSDPA

Abstract

This paper works comprises on the analysis of IEEE 802.16 WiMAX standards and the performance analysis of its physical layer using the OFDM adaptive modulation and it uses the concept of cyclic prefix that adds additional bits at the transmitter end. The signal is transmitted through the channel and it is received at the receiver end, then the receiver removes these additional bits in order to minimize the inter symbol interference, to improve the bit error rate and to reduce the power spectrum. An Additive white Gaussian noise (AWGN) channel model is used with Rayleigh fading to resemble the real world scenario. The transmitter and receiver are assumed to be in fixed positions and the channel coding is not used. The transmitted and received signals are considered to in perfect sync with each other in time and frequency. Losses from feeder cables, joints, connectors, jumpers are not taken in consideration. In our research work, we investigated the physical layer performance on the basis of bit error rate, signal to noise ratio, power spectral density and error probability. These parameters are discussed in two different models. The first model is a simple OFDM communication model without the cyclic prefix, while the second model includes cyclic prefix. The study reviewed scientific articles that provide in-depth knowledge that WiMAX provides increased throughput and better protection against multi path propagation and self interference as compared to HSDPA, furthermore, in this paper different aspects of the model were investigated and with MATLAB simulations it has been demonstrated that lower modulation schemes provide better performance in noisy conditions. Higher modulation schemes provide higher data rates, but encounter high BER in noisy and low SNR conditions.