International Journal of Electrical and Electronics Research ISSN 2348-6988 (online) Vol. 8, Issue 4, pp: (48-53), Month: October - December 2020, Available at: www.researchpublish.com
REDUCTION OF PAPR IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM USING OPTIMIZATION METHODS 1
K. Phani Rama Krishna, 2Md.Habibulla
1
P V P Siddhartha Institute of Technology,Kanuru,Vijayawada, Andhra Pradesh, India.
2
P V P Siddhartha Institute of Technology,Kanuru,Vijayawada, Andhra Pradesh, India Author email id: kprkrishna007@gmail.com, honeyhabeeb@gmail.com
Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a form of multicarrier modulation Technique. In this System orthogonally placed subcarriers are used to carry the data from transmitter end to receiver end and has found its way to the high speed wireless and mobile communication world. It has excellent immunity against fading and ISI but its major drawback is peak to average power reduction (PAPR) of the transmitted signal. So many methods are proposed to reduce large PAPR. But most of the techniques are complex. In this paper various optimization technique GA, PSO, Hybrid algorithms are proposed to optimize phase factors in PTS technique of OFDM system. The simulation Results of proposed algorithms are compared with OFDM Results. Keywords: GA, OFDM, PSO, PTS, PAPR.
I. INTRODUCTION OFDM is Revolutionary communication Technology because it forms the basis for 4G wireless communication system .It is a special form of multicarrier modulation technique which is particularly suited for transmission of data over a dispersive channel. High data rates are possible in OFDM system as each Individual narrow band channel experiences flat fading, which causes negligible ISI, because of this advantages OFDM widely used in different applications like DAB, DVB, standard Like IEEE 802.11a/g/, Hyperlan2 [1]. But the main drawback Of OFDM system is large PAPR. This large PAPR in OFDM system causes increase in dynamic Range of A to D and D to A convertors used in OFDM system. So it requires higher bit resolution for ADC or DAC, which will increase the total system complexity. More Over at higher Input power levels the high power amplifier (HPA) gets saturation region which is non linear in nature, results intermodulation and out of band components which are undesirable [2]. Several Techniques have proposed to reduce high PAPR in OFDM system like clipping Block Coding, Partial Transmit sequence, Selective mapping. But most of techniques are complex. Among these PTS is most promising one than other. In PTS technique the phase factors can be optimized to get less PAPR using Optimization Algorithms [3-8]. The most well-known Optimization algorithms are particle swarm optimization and genetic algorithm (GA). GA depends on the ideas of natural selection and represents a random search used to solve optimization problems. Particle swarm optimization used to solve non-linear continuous optimization problems. In this paper we combining these two optimization algorithms by mixing the search abilities of both approaches results to be a good algorithm called Hybrid algorithm. In these approaches the output of PSO is cascaded to the input of genetic algorithm. So, two times optimization takes place to get less PAPR in OFDM system. The rest of the paper is organized as follows. In second section we present basic concepts of OFDM system and PAPR, PSO and Genetic algorithm. In third section we introduces hybrid algorithm for solving optimization algorithms. In section four we show the performance results of proposed algorithms are compared with conventional OFDM results.
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