Performance Improvement of OFDM System Using New Scrambling Technique with Precoded Methods

2nd International Conference on Sustainable Engineering Techniques

工业技术（总论）

Abdullah, Muntadher Kadhim^1 ; Ibada, Ali Jawad^1

Computer Technical Engineering Department, College of Technical Engineering, Islamic University, Najaf, Iraq^1

关键词: Bit error rate (BER) performance;    DCT and WHT;    Discrete Cosine Transform(DCT);    Orthogonal frequency division multiplexing systems;    PAPR;    Peak to average power ratio;    Scrambling techniques;    Walsh-Hadamard transform;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/518/4/042028/pdf
DOI  :  10.1088/1757-899X/518/4/042028

学科分类：工业工程学

来源: IOP

【 摘 要 】

One of the challenging issues for Orthogonal Frequency Division Multiplexing (OFDM) system is its high Peak to Average Power Ratio (PAPR). This degrades performance of the system. In this paper, a new scrambling algorithm to reduce PAPR is presented. The new algorithm uses chaos system to generate several Chaos Binary Sequences (CBS) that scrambled with the data symbols to get several sequences. Only one sequence is chosen with smallest PAPR value for transmission. To reduce the PAPR more and improve Bit Error Rate (BER) performance of the new scrambling algorithm, precoded methods are used. Two precoded methods are presented in this work: Discrete Cosine Transform (DCT) and Walsh Hadamard Transform (WHT). Simulation results using MATLAB show that when number of subcarriers is 1024 and number of CBS is 8, the PAPR is approximately equal to 7 db by using new scrambling technique only. While the PAPR is approximately reduced by 1 db when using WHT with new technique. Finally, when using DCT with new technique, the PAPR is approximately reduced by 3.8 db. Also DCT with new technique gives better BER performance than WHT with new technique.