A Performance Analaysis of BPSK OFDM System by Novel Based Haar Wavelet

Abstract

orthogonal frequency division multiplexing (OFDM) is the most popular modulation technique in modern wireless communication systems. Even though there are many advantages of OFDM, it has two main drawbacks: High peak-to-average power ratio (PAPR) and frequency offset. In this paper the issue of PAPR in OFDM is discussed. Due to the large number of subcarriers used, OFDM systems have a large dynamic signal range with a very high peak-to-average-power ratio (PAPR) which makes OFDM sensitive to nonlinear effects. This paper proposes a novel Haar-Wavelet based BPSK OFDM system. The Haar Wavelet transformation decomposes the data symbol sequence like half of the data symbols are zeros and the rest are √2 or -√2 and we can have the PAPR reduced by 3dB at most, compared with the conventional OFDM system. In this paper we propose a novel decoding algorithm for the proposed OFDM system, derive the bit error rate performance in theory. We compare cumulative distribution function for PAPR for the proposed OFDM v/s conventional OFDM and finally we compare the BER performance of our proposed OFDM system with the conventional one.KEYWORDS: Peak-to-average power ratio(PAPR); Bit error rate(BER); Haar Wavelet; Orthogonal frequency division multiplexing(OFDM); I.INTRODUCTIONAfter more than thirty years of research and developments carried out in different places, orthogonal frequency division multiplexing (OFDM) has been widely implemented in high speed digital communications. Due to the recent advancements in digital signal processing (DSP) and very large scale integrated circuits (VLSI) technologies, the initial obstacles of OFDM implementations do not exist anymore. Mean-while, the use of Fast Fourier transform (FFT) algorithms has eliminated arrays of sinusoidal generators and coherent demodulation required in parallel data systems and made the implementation of the technology cost effective. In recent years OFDM has gained a lot of interest in diverse communication applications. This has been due to its favorable properties like high spectral efficiency and robustness to channel fading. Recently OFDM has become the technique of choice for many broadband applications, such as asymmetric digital subscriber line (ADSL) modems, digital audio broadcasting (DAB)[1], digital video broadcasting(DVB)[2] and wireless local area networks (WLAN) systems (IEEE 802.11a [3], IEEE 802.11g [4]. In the conventional serial data transmission system, the information symbols are transmitted sequentially where each symbol occupies the entire available spectrum bandwidth. But in the OFDM system, the information is converted to N parallel sub channels and sent at lower rates using frequency division multiplexing. The subcarrier frequency spacing is selected carefully such that each subcarrier is located on the other sub-carrier zero crossing points. This implies that there is overlapping among the subcarriers but will not interfere with each other, if they are sampled at the subcarrier frequencies. This means that all subcarriers are orth...