Effects of Spectral Null Codes on PAPR and BER Performance in OFDM Systems

Abstract

Spectral null codes has a wide range of applications, and it has been shown that the Power Spectral Density (PSD) of messages in Orthogonal Frequency Division Multiplexing (OFDM) systems can be shaped to have nulls at designed frequencies. Peak to average power ratio (PAPR) is a common problem with OFDM, resulting in power intensive and more expensive modulators which are not suitable for modern mobile devices with limited battery life. The use of PAPR reduction techniques in OFDM is crucial in order to make it compatible with modern devices. We investigate the effect of spectral null codes on the performance of the OFDM system. In particular we focus on the bit error rate performance (BER) and the PAPR performance. We show that the use of spectral null codes has no negative impact on either the BER or PAPR performance, as expected. We conclude that the spectral null coding technique may be used to shape the PSD in OFDM systems without causing any significant negative impact on performance.