Analysis of Optimum Technique for PAPR Reduction in UFMC System

Abstract

The fifth Generation of communication has to support many applications like the Internet of Everything (IoE) and Machine Type Communication (MTC). The proposed universal filtered multi-carrier (UFMC) technique is one of the best techniques for fifth-generation (5G) communication. UFMC is expected to achieve low latency, robustness against synchronization errors and frequency offset, short-packet burst support, and reduce out-of-band (OoB) radiation that leads to higher spectral efficiency. Although the UFMC system offers many advantages as mentioned before, being a multicarrier transmission technology, it suffers from a high peak-to-average power ratio (PAPR), which degrades the efficiency of the High-Power Amplifier (HPA) and makes the UFMC transmitter inefficient. Therefore, an optimum PAPR reduction technique to reduce the high PAPR of the UFMC system has to be proposed. The proposed technique is a hybrid technique that consists of a combination of Generalized Chirp-Like (GCL) precoding and Selective-Mapping techniques (SLM). A comparative analysis of the performance of Generalized Chirp-Like precoding methods, SLM, and hybrid methods are by CCDF of the PAPR and the bit error rate (BER) and simulation results show that proposed SLM based GCL UFMC outperform the conventional techniques

Introduction

I. INTRODUCTION

Like 4G LTE, the fifth Generation is also Orthogonal Frequency Division Multiplexing based and will operate based on the same mobile networking principles. However, the recent 5G technology has to manipulate a distinct group of users with various demands. OFDM is one of the best choices but in addition to the PAPR problem, it is sensitive to offsets both time and frequency. The high PAPR problem causes serious issues like spectral efficiency loss. Due to low Out-of-Band (OOB) emission FBMC (Filter Bank MultiCarrier) and UFMC (Universal Filter MultiCarrier) has more spectral efficiency compared to OFDM. Among them, UFMC is better than FBMC due to its short-packet burst support. UFMC is the generalization of both OFDM and UFMC. Instead of filtering a full-band like OFDM and each subcarrier like FBMC, UFMC divides a full band into sub-band and filter each sub-band (group of sub-carriers). Like OFDM and FBMC, UFMC is less complex and has good spectral efficiency. When compared with FBMC, filter length is reduced in UFMC due to its grouping of sub-carriers. Even UFMC has different advantages, it also has high PAPR which is the major drawback.

There are several techniques were used to solve the PAPR issue. But only a few for UFMC are available in the literature. In [1], the clipping technique is used. Clipping is a plain technique to reduce PAPR but while transmitting the signal it gives rise to clipping noise and in-band and Out-of-Band (OoB) interference, which results in performance degradation. To reduce clipping noise in [2], they introduce filtering after clipping. But clipping followed by filtering cause some peak regrowth. Introduces distortions in the transmitted signal which reflects system BER. To overcome the peak regrowth in [3] enlipping is added after filtering (clipping-filtering-clipping). But, clipping based enlipping will cause an increase in average power, which will degrade IBO performance which will lead to overall system performance degradation.              

In [4], the Companding technique is used to reduce PAPR. It is easy and less complex. It has two types: Mu-law companding and A-law companding.The Companding transform introduces some distortion and increases receiver noise. PTS (Partial Transmit Sequence) is used in [5] in which the main data block is split up into sub-blocks. The PAPR of the combination is minimized by rotating the subcarriers in each sub-block with the same phase factor. But PTS reduces PAPR with some complexity and spectral efficiency loss. In [6], SLM is used to reduce PAPR. Here it has two approaches: E-SLM and P-SLM. The disadvantage is that it requires side information which causes the spectral efficiency loss. In [7], the Non-Linear Companding Technique is combined with the precoding technique to reduce PAPR.

The hybrid technique shows the best result for PAPR reduction than others but the NLCT technique is difficult to implement. In this paper, an efficient SLM technique is combined with the GCL precoding technique to reduce the PAPR for UFMC. The proposed technique outrun the existing techniques. The rest of this paper is organized as follows; Section II presents the UFMC system model and a brief explanation about PAPR. Section III explains the proposed scheme. Simulation results are provided in Section IV and finally, section V concludes the paper.

Conclusion

In this paper, to reduce the PAPR of the UFMC system a proposed hybrid PAPR reduction technique is used, which is an optimum technique. A comparative analysis of GCL precoding, Selective mapping, and SLM-based GCL precoding is implemented. The analysis proved that the hybrid technique improves PAPR reduction compared to a normal UFMC system. The proposed SLM-GCL- UFMC scheme performance was meticulously explored by using MATLAB simulations. Numerical results have shown that the proposed scheme outruns the precoding-based UFMC scheme, standard UFMC scheme, and standard OFDM, respectively. Furthermore, the proposed system utilizes linear precoding and SLM phase rotations to reduce the PAPR, which improves the robustness of the proposed scheme in fading multipath environment. Additionally, the proposed method improves the efficiency of the transmitter without any kind of power increase. As future work, the proposed SLM-based GCL precoded UFMC needs to be analysed to improve both the PAPR and BER characteristics of UFMC systems on a frequency selective channel.

References

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Copyright

Copyright © 2023 Rathna. R, Pushpalatha. V, Bhagyaveni. M. A . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.