A Novel ZCS-Clipping Precoding Technique for PAPR Reduction using DCT-OFDM in Vehicular Channels

Abstract

IEEE 802.11p defines an international standard for wireless access in vehicular environments. It is normally designed for operating at high user mobility. Thus, decreasing the signal bandwidth to 10 MHz in IEEE 802.11p makes the communication more efficient for the vehicular channel. Furthermore, the Orthogonal Frequency Division Multiplexing (OFDM) methodology is commonly used to mitigate the Inter-Symbol Interference (ISI) occurred over a wireless channel. However, the OFDM suffers from certain drawbacks including higher system complexity due to the generation of the peak to average ratio (PAPR). The objective of this study is to reduce the high PAPR resulted from adapting the OFDM system to vehicular networks. In this paper, we propose a novel precoding Zadoff-Chu Sequence (ZCS) combined with the Clipping technique for PAPR reduction in OFDM based on the Discrete Cosine Transform (DCT). The proposed technique which is based on precoding the constellation symbols of the vehicular channels with DCT succeeds to decrease the PAPR ratio up to 4dB for 64 subcarriers.

Controlling High PAPR in Vehicular OFDM-MIMO using Downlink Optimization Model under DCT Transform

“…In the proposed model, the ZCS pre-coding technique is deployed to reshape the IDCT matrix row and reform the constellation symbols before the channel propagation step [34]. The main advantages of ZCS is its ability to provide constant amplitude for the output signal with optimum correlation properties as well as reduce the cost and complexity of output signal [35,36]. Thus, the peak power of the transmitted signal can be under control.…”

“…Then, they are converted from serial to parallel form using the serial-toparallel (S/P) converter in order to be sent through the roadside antennas. At this moment, the resulted sequence is defined as The DCT/IDCT transform is employed in this model [22,36,38]. Similar to other transformation methods, the DCT relies on a sum of cosine function that is fluctuating at different frequencies to define a finite sequence of data points.…”