BER Reduction in OFDM Systems using ZCT Matrix Transform

Abstract

In recent years, Orthogonal Frequency Division Multiplexing (OFDM) is preferred for transmission over a dispersive channel. It is because of its several advantages such as high spectral efficiency, low implementation complexity, less vulnerability to echoes and non–linear distortion. However, it has few limitations such as peakto-average-power ratio (PAPR) and bit error rate (BER), which determines the system’s power efficiency. High PAPR is one of the major drawbacks in OFDM systems, which causes a significant level of signal distortions, when the modulated signals are amplified through high power amplifiers (HPAs). In particularly, high PAPR increases the complexity of Analogue to Digital (A/D) and Digital to Analogue (D/A) converters and also reduces the efficiency of HPAs. A high PAPR and high noise (e.g. AWGN) may significantly distort the signal, resulting in high BER on demodulation of the received signal. Therefore, PAPR & BER reduction is very essential. For this purpose, a Zadoff-Chu matrix Transform (ZCT) based precoding and postcoding techniques are quantitatively evaluated in this paper in terms of its parameters q and r. From the analysis, it is inferred that an optimum selection of q and r can lead to a significant level of reduction in BER.