On blind estimation with reduced complexity in CSS-OFDM systems

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) signals suffer from high PAPR (Peak to Average Power Ratio). Cyclic shifted sequences (CSS) was proposed as a solution to high PAPR. CSS reduces PAPR stochastically by giving some independent cyclic shifts to the time-domain signals of clusters. In CSS, however, we must transmit side information (SI) regarding the cyclic shift. Although a blind method to estimate SI at the receiver was also proposed, its computational complexity increases as not only the number of subcarriers but also the degree of multi-level modulation increases. In the present paper, to conquer this drawback, we consider decreasing the number of subcarriers used for estimating SI. This paper shows that we achieve almost the same bit error rate as the conventional scheme with half the number of subcarriers under a certain condition. We also study the relationship between the number of subcarriers per cluster and estimation accuracy.