A Proposed Method to Reduce the BER in Wavelet based OFDM

Abstract

Long term evolution (LTE) selects orthogonal frequency division multiplexing (OFDM) and its single-carrier counterpart SC-FDM as the basic transmission schemes. OFDM is a very interesting approach for high data rate transmission in a Gaussian channel and multipath fading environment that leads to inter symbol interference (ISI). In this paper, a proposed convolutional encoder model is used to improve the error rate performance of OFDM system, by using discrete wavelet transform (DWT) instead of fast Fourier transform (FFT) to reduce ISI. The performance of OFDM based on DWT using M-ary quadrature amplitude modulation (M-QAM) as a modulation scheme to achieve high data rate. The simulation results demonstrate that, the bit error rate (BER) is improved for a proposed convolutional encoder model as compared with the previous work. General Terms LTE, MATLAB simulator

Performance Improvement by using a Concatenated Levels of Encoding in Wavelet based OFDM Systems

“…The results studied for series concatenated encoder/decoder levels at two or more convolutional or hamming encoder/decoder and a combination of hamming and convolutional encoder [14].…”

Improved Interference Cancellation for Downlink Wavelet Based Multi-Carrier CDMA System

“…FFT based MC-CDMA uses the cyclic prefix (CP) to reduce both of the intercarrier interference (ICI) and inter-symbol interference (ISI). The cyclic prefix leads to wasting about 12.5% of the total bandwidth [4]. Elimination of the MAI, the ICI, and the ISI saves the required power for transmission to achieve the desired signal-to-noise ratio (SNR) and to enable transmission over several channels with a limited power [1].…”