Sharif Digital Repository

An efficient, easy to implement method for OFDM and DMT Peak to Average Power Ratio (PAPR) reduction is proposed based on constellation extension. A PAPR reduction of more than 5 dB at clip rate of 10-5, is achieved with no rate loss and improved noise margin with low complexity. Various versions of the proposed method have been studied and compared in terms of PAPR reduction, complexity and average power, with each other and earlier methods. © Springer-Verlag Berlin Heidelberg 2002  

In this paper, we introduce a new bound for the peak of the continuous envelope of an OFDM signal based on the maximum of its corresponding oversampled sequence, that is considerably tighter than the recent results presented in [4]. The proposed bound is then used as the basis of our study in two parts. In the first part, we find an upper bound for the regrowth of the peak of the digitally clipped oversampled sequence after discrete to continuous conversion. We also show that for oversampling rates greater than π/√2, the peak regrowth percentage depends only on oversampling rate, regardless of the number of subcarriers. In the second part, we propose new and tight relative error bounds for... 

Orthogonal frequency division multiplexing (OFDM) is one of the widely used multiplexing techniques in wireless communications and especially cognitive radio networks. One of the key challenges of this technique is its high peak to average power ratio (PAPR) of the transmitted signal. This paper, introduces a new approach to PAPR reduction of OFDM signals using harmony search algorithm (HSA) based on the partial transmit sequence (PTS) method. The simulation results demonstrate that the proposed algorithm has better PAPR reduction performance as an accurate and low complexity approach for OFDM systems  

The orthogonal frequency division multiplexing (OFDM) modulation technique is one of the key strategies for multiuser signal transmission especially in smart grids and wind farms. This paper introduces an approach for peak-to-average power ratio (PAPR) reduction of such signals based on novel global harmony search (NGHS) and partial transmit sequence (PTS) schemes. In PTS technique, the data block to be transmitted is partitioned into disjoint subblocks, which are combined using phase factors to minimize PAPR. The PTS requires an exhaustive search over all combinations of allowed phase factors. Therefore, with respect to the fast implementation and simplicity of NGHS technique, we could... 

OFDM is a multicarrier modulation scheme with high bandwidth efficiency and robustness to multipath environment used in high data rate transmission. However, a drawback of this system is the large Peak-to-Average-Power Ratio (PAR) of the transmit signal which makes its straightforward implementation quite costly. PAR in an OFDM based system can be reduced significantly by PTS method for which data recovery requires side information (SI) about the phases used at transmitter. Sending SI, not only reduces the rate, but also increases BER, for any error in SI detection can damage a large amount of transmitted information. By introducing a new phase set, we propose a PTS based method for MPSK...