Reduction of Peak to Average Power Ratio using Selective Mapping Technique of an OFDM Signal: An Analysis

Orthogonal Frequency Division Multiplexing (OFDM) is a optimistic and very popular modulation technique in multicarrier domain which is quite promising regarding the issues of interferences present in next generation mobile communication systems. It deployed in the area where high data rate and low latency required while efficiency will be as better as possible. The critical problem in OFDM system is maintaining low PAPR (peak to average power ratio) because it reduces the performance of system. There are several techniques which are used to overcome problem of high PAPR in OFDM modulation system. One of the techniques is Selective Mapping (SLM) which comes in distortion less criteria. In this paper analysis of PAPR reduction of an OFDM system for distortion less transmission criterion is shown. We have also used some mathematical equations to calculate and simulate its performance. It’s also shown that SLM method grants the user a better PAPR reduction while having high complex circuitry

Enhancement of Selective Mapping Technique for Peak-To-Average Power Ratio Reduction in OFDM using Normalized Hilbert Matrix

Orthogonal Frequency Division Multiplexing (OFDM) is good multicarrier transmission system used for broadband wireless communication systems owing to it is numerous benefits such as high bandwidth efficiency, high transmission rate, and robustness against multi path problem. However, one of the hitches of OFDM high Peak-to-Average Power Ratio (PAPR) of the transmitted signal, which results in signal distortion and reduced power amplifier efficiency. Selective Mapping (SLM) is attractive distortion less method for PAPR reduction. The performance of this technique in reducing the PAPR is largely affected by the magnitude of phase rotation vectors. It also requires to  transmit the selected phase rotation vectors that produce the signal with the lowest PAPR to the receiver end for the recovery of the original data. In this paper, two normalization procedures in conjunction with the Hilbert matrix are used to obtain phase rotation vectors for the SLM technique to further reduce the PAPR value. The reduction of PAPR is desirable in order to have a better power efficiency of the amplifier. The simulation results demonstrated that the enhanced SLM technique using normalized Hilbert matrix achieved a better PAPR reduction compared to SLM using Hilbert matrix without normalization with 14.0%, and 14.0%  percentage improvement. Another benefit of this method is that the matrix can be generated at the receiver end to obtain the data signal, thus eliminating the transmission of side information with the original data

A Low-Complexity SLM PAPR Reduction Scheme for OFDMA

In orthogonal frequency division multiplexing (OFDM) systems, selected mapping (SLM) techniques are widely used to minimize the peak to average power ratio (PAPR). The candidate signals are generated in the time domain by linearly mixing the original time-domain transmitted signal with numerous cyclic shift equivalents to reduce the amount of Inverse Fast Fourier Transform (IFFT) operations in typical SLM systems. The weighting factors and number of cyclic shifts, on the other hand, should be carefully chosen to guarantee that the elements of the appropriate frequency domain phase rotation vectors are of equal magnitude. A low-complexity expression is chosen from among these options to create the proposed low-complexity scheme, which only requires one IFFT. In comparison to the existing SLM technique, the new SLM scheme achieves equivalent PAPR reduction performance with significantly less computing complexity. MATLAB tool is used for simulating the proposed work

A Low-Complexity SLM PAPR Reduction Scheme for OFDMA

In orthogonal frequency division multiplexing (OFDM) systems, selected mapping (SLM) techniques are widely used to minimize the peak to average power ratio (PAPR). The candidate signals are generated in the time domain by linearly mixing the original time-domain transmitted signal with numerous cyclic shift equivalents to reduce the amount of Inverse Fast Fourier Transform (IFFT) operations in typical SLM systems. The weighting factors and number of cyclic shifts, on the other hand, should be carefully chosen to guarantee that the elements of the appropriate frequency domain phase rotation vectors are of equal magnitude. A low-complexity expression is chosen from among these options to create the proposed low-complexity scheme, which only requires one IFFT. In comparison to the existing SLM technique, the new SLM scheme achieves equivalent PAPR reduction performance with significantly less computing complexity. MATLAB tool is used for simulating the proposed work

Comparison of Various Peak To Average Power Reduction Techniques

In this paper we study various peak to average power reduction techniques and find the advantages and disadvantages of these techniques.The main disadvantage is high PAPR in transmission for high-speed transmission due to its spectrum efficiency and channel robustness. OFDM signals are mostly responsible for the problem of PAPR Keywords: High power amplifier (HPA), peak-to-average power ratio (PAPR

Reduksi Peak-To-Average Power Ratio Pada Sistem STBC MIMO-OFDM Dengan Metode Selected Mapping Dan Partial Transmit Sequence

Teknik OFDM merupakan teknik multicarrier yang mengefisienkan bandwidth. Penggunaan teknik OFDM dapat mengatasi multipath fading dan intersymbol interference (ISI). Namun demikian, OFDM mempunyai dua kelemahan, salah satunya adalah peak-to-average power ratio (PAPR) yang tinggi. PAPR yang tinggi akan menyebabkan distorsi nonlinear pada high power amplifier (HPA) karena HPA membatasi keluaran dengan nilai tertentu dan mengurangi efisiensi daya amplifier. Oleh karena itu, PAPR yang tinggi harus direduksi. Metode reduksi PAPR yang diajukan adalah dengan menggunakan metode Selected Mapping (SLM) dan Partial Transmit Sequence (PTS). Kedua metode ini memiliki kekurangan dalam hal kompleksitas multiplikasi dan penjumlahan dan adanya bit side information yang harus dikirimkan ke receiver. Oleh karena itu, penulis mengajukan pengembangan dari metode tersebut dengan memodifikasi faktor rotasi fasa menjadi pattern konversi terdefinisi yang lebih adaptif pada SLM, dan mengurangi iterasi pembangkitan faktor rotasi fasa pada metode PTS dengan pendefinisian faktor rotasi fasa yang terbatas. Hasil simulasi dengan 1000 simbol OFDM menunjukkan bahwa kemampuan reduksi PAPR pada metode m-SLM dan m-PTS mendekati kemampuan reduksi metode konvensional. Bit error rate (BER) yang dihasilkan juga mengalami perbaikan dibandingkan BER tanpa reduksi. m-SLM secara keseluruhan mengungguli kinerja dari m-PTS, baik pada nilai reduksi PAPR maupun pada perbaikan BER

Low Complex PAPR Reduction Schemes for OFDM Systems

In this thesis, three low-complex PAPR reduction schemes for OFDM systems are proposed. All the proposed schemes can be considered as modi ed versions of the conventional SLM scheme, which can signi cantly reduce high PAPR of OFDM signals with no distortion. In the rst proposed scheme, a new set of the candidate sequences is generated by partial phase weighting in the time domain and the combination of sub-blocks by applying IFFT properties. In the second scheme which is based on a combination of SLM and PTS, a simple phase optimization technique is introduced. The third scheme forms di erent 16-QAM signals from 2 QPSK signals. Also, the circular convolution part in TPPW-SLM, which is also a part of Class-III SLM, is applied