Hybrid Peak to Average Power Ratio Reduction Technique in QPSK-Based Orthogonal Frequency Division Multiplexing Systems

Abstract

Orthogonal Frequency Division Multiplexing had been chosen to be the main candidate as the air interface for the high data rate transmission systems. Orthogonal Frequency Division Multiplexing offers high spectral efficiency since it makes use of the available bandwidth due to orthogonality subcarriers behaviour. One of the drawbacks of Orthogonal Frequency Division Multiplexing system is the high Peak-to-Average Power Ratio, which decreases the high power amplifier’s efficiency. Many techniques are used to reduce Peak-to-Average Power Ratio such as, clipping, Partial Transmitted Sequence and selected mapping, etc. This paper presents a hybrid technique comprised of Partial Transmitted Sequence and improved clipping technique to reduce high Peak-to-Average Power Ratio. The performance of the proposed technique was compared with different reduction techniques using Matlab/Simulink simulation. The results showed that using Partial Transmitted Sequence only a reduction of 3.4 dB is achieved with 5×10-6 Bit Error Rate, while using the improved clipping technique, a reduction of 0.7 – 4.4 dB is achieved for 0.2– 0.8 weighting factors with 7×10-6 to 2×10-4 Bit Error Rate. Our proposed technique reduces Peak-to-Average Power Ratio and maintains a good Bit Error Rate performance depending on the changing of a weighting factor. For a weighting factor of 0.2 to 0.8, the Peak-to-Average Power Ratio reduction is about 4 – 7 dB in comparison with the desired Orthogonal Frequency Division Multiplexing signal, which is better than the above technique. In addition, the Bit Error Rate does not change when using Partial Transmitted Sequence with the Improved Clipping technique, which represents a good performance for the systems using Orthogonal Frequency Division Multiplexing as an air interface.
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