DFT-Based OFDMA System with Phase Modulation for Broadband Communication

Farouk Abduh Kamil Al-Fuhaidy

doi:10.11648/j.ajece.20190301.11

Abstract

This paper proposes, a DFT-based OFDMA with phase modulation (DFT-OFDMA-PM) system. One main advantage of the phase modulated system is the constant envelope (CE) resulted signal, i.e, 0 dB PAPR, the second advantage is the ability to improve the diversity of multipath channels. These advantages have been exploited in the proposed system of this paper. The performance of the proposed system in terms of the bit error rate (BER) is studied and investigated and compared to the previously proposed DCT-OFDMA-PM system and the conventional OFDMA system without PM via computer simulation. The key parameter that affects the performance of the PM systems, the modulation index, is also studied and the optimum value is selected using exhaustive simulation scenarios. Moreover, the PAPR is also simulated for the proposed system and compared to the conventional system. Simulation results show the significant improvement of the proposed system in terms of PAPR and BER when compared to the conventional system. The simulation results for the proposed system show the effectiveness of the proposed system for wireless broadband communications.

Highlights

Wireless digital communication is rapidly expanding, resulting in a demand for wireless systems that are reliable and have a high spectral efficiency [1]
Orthogonal frequency division multiple access (OFDMA) is an attractive technology to deal with the detrimental effects of multipath fading, but it faces several inherent disadvantages such as the high peak-to-average-power ratio (PAPR) and the sensitivity to carrier frequency offsets [2, 3]
We note that the abbreviations DFT-LOFDMA-phase modulation (PM) and DFT-IOFDMA-PM refer to localized and interleaved subcarrier mapping respectively

Summary

Introduction

Wireless digital communication is rapidly expanding, resulting in a demand for wireless systems that are reliable and have a high spectral efficiency [1]. Signals with a high PAPR require highly linear power amplifiers to avoid excessive intermodulation distortion. To achieve this linearity, the amplifiers have to operate with a large backoff from their peak power. These techniques can be classified into two groups, the first one which is called distortion reduction techniques, such as, windowing and clipping [7]. The resulted signal by the PM-based system has a constant envelope (i.e. 0 dB PAPR) which allows the PA to operate near the saturation region, maximizing the power efficiency.

Objectives

Results

Conclusion