PERFORMANCE COMPARISION OF PILOT-BASED CHANNEL ESTIMATION METHOD IN OFDM SYSTEM OVER FADING CHANNEL

Abstract

Wireless channel is unknown and inclined to time dispersion, which causes inter symbol interference (ISI) and fading. OFDM is one of the most capable core technologies in the fourth generation of wireless communication systems. OFDM has the advantage over the conventional single-carrier modulation schemes when the channel is frequency-selective fading and widely used in current wireless networks. In this thesis work the performance of two pilot-based channel estimation algorithms; namely, least square (LS) and Minimum Mean Square Error (MMSE) with corresponding channel interpolation technique is investigated for digital communication systems. Channel estimation is a technique that can be used to design a channel in a particular surrounding based on known train symbols which is inserted in the input of transmitter end and tested at the receiver end. This thesis performs , analysis of channel estimation algorithms based on bit error rate (BER) and signal to noise ratio (SNR) minimizing the error distance between the transmitted and received data. To estimate the channel coefficients; The MATLAB plot can perform for QAM, 16QAM, and 64QAM constellations. For different international telecommunication union (ITU) channel models Such as, the portable outdoor (PO), portable indoor (PI), Rural Area six path (RA6), Typical Urban six path (TU6), and Rayleigh channel models. Typical urban channel model has better at higher order modulation. From the MATLAB results, LS and MMSE algorithms are compared based on their pilot ratio and channel length. LS estimation has better at high SNR value compared to MMSE estimation.