Selected Mapping Scheme Research Articles

A novel SLM scheme for peak-to-average power ratio reduction in WOLA-OFDM system

This paper addresses high peak-to-average power ratio (PAPR) issue in the recently invented weighted overlap and add-orthogonal frequency division multiplexing (WOLA-OFDM) system. The selective mapping (SLM), one of the most widely used PAPR reduction schemes in OFDM-based multicarrier transmission strategies, can be used to reduce the PAPR of WOLA-OFDM signals. However, the overlapping of symbol extensions in the WOLA-OFDM transmitter considerably deteriorates the performance of SLM. To overcome this problem, we have developed an efficient SLM scheme named dual symbol optimization-SLM (DSO-SLM) for the WOLA-OFDM system. In this new scheme, instead of reducing the PAPR of adjacent symbols separately as in conventional SLM, each symbol is evaluated together with its overlapping predecessor symbol while searching for the optimal transmission signal with minimized PAPR. With the usage of DSO procedure, it becomes possible to enhance the performance of conventional SLM in the WOLA-OFDM system.

Selective Mapping scheme based on Modified Forest Optimization Algorithm for PAPR reduction in FBMC system

Filter Bank Multicarrier(FBMC)is considered as one of the most standardized waveform for fifth generation (5G) mobile communication system application FBMC endures lot of nonlinear effects which occurs because of high Peak Average Power Ratio (PAPR). High value of PAPR due to the large dynamic range of multicarrier signal is one of the most significant issues in FBMC multicarrier based modulation technique. This paper presents one investigated PAPR reduction technique named as Selected Mapping (SLM) to minimize high PAPR by utilizing the complex signal divide into real and imaginary parts and then select minimum PAPR signal based on Modified Forest Optimization Algorithm (MFOA)to achieve good PAPR which can maintain the FBMC based system performance with a required Bit Error Rate (BER). The associated method was produced with the aim of optimize the phase factors so that the phase rotation operation is accomplished to minimize PAPR by fixing the MFOA into the conventional SLM. The simulation results demonstrate that the proposed technique gives better performance in terms of BER and PAPR compared to other SLM based optimization techniques.

Low-complexity selective mapping technique for PAPR reduction in downlink power domain OFDM-NOMA

To support ultra-massive connectivity, non-orthogonal multiple access (NOMA) techniques are expected to be used in 6G instead of conventional orthogonal multiple access (OMA) techniques. Furthermore, given that orthogonal frequency division multiplexing (OFDM) was used by 4G and 5G, NOMA is expected to be combined with OFDM to mitigate frequency selectivity in multipath channels. However, after passing through nonlinear high power amplifiers (HPAs), OFDM-NOMA has reportedly suffered from nonlinear distortion due to the high peak-to-average power ratio (PAPR) problem, thus reducing users’ achievable data rates, sum rate capacity, and users’ bit error rate after going through nonlinear HPAs. Many PAPR reduction techniques have been introduced in the literature; however, high PAPR reduction gain comes at the expense of computational complexity. In this paper, a novel selective mapping (SLM) scheme for PAPR reduction in OFDM-NOMA systems is proposed. By utilizing the structure of the OFDM-NOMA transmitter, the proposed SLM scheme achieves the same performance as that of the conventional SLM scheme while requiring less computational complexity.

Selective Mapping Scheme for Universal Filtered Multicarrier

The next step in mobile communication technology, known as 5G, is set to go live in a number of countries in the near future. New wireless applications have high data rates and mobility requirements, which have posed a challenge to mobile communication technology researchers and designers. 5G systems could benefit from the Universal Filtered Multicarrier (UFMC). UFMC is an alternate waveform to orthogonal frequency-division multiplexing (OFDM), in filtering process is performed for a sub-band of subcarriers rather than the entire band of subcarriers Inter Carrier Interference (ICI) between neighbouring users is reduced via the sub-band filtering process, which reduces out-of-band emissions. However, the UFMC system has a high Peak-to-Average Power Ratio (PAPR), which limits its capabilities. Metaheuristic optimization based Selective mapping (SLM) is used in this paper to optimise the UFMC-PAPR. Based on the cognitive behaviour of crows, the research study suggests an innovative metaheuristic optimization known as Crow Search Algorithm (CSA) for SLM optimization. Compared to the standard UFMC, SLM-UFMC system, and SLM-UFMC with conventional metaheuristic optimization techniques, the suggested technique significantly reduces PAPR. For the UFMC system, the suggested approach has a very low Bit Error Rate (BER).

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.

Low complexity partition-recombined SLM scheme for reducing PAPR in coherent optical OFDM systems

High peak-to-average power ratio (PAPR) remains the main challenge of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. Selective mapping (SLM) is a well-known effective PAPR reduction technique, but it suffers from high computational complexity. To reduce the PAPR of OFDM signals, a low-complexity, partition-recombined SLM (PRSLM) scheme is proposed. The PRSLM scheme can generate more candidate signals than that of the conventional-original SLM (COSLM) scheme. The real and imaginary components of time-domain symbols are first partitioned, and then recombined to generate new candidate signals, which reduces computational complexity significantly. A 40-GBaud single-polarization CO-OFDM transmission system is set up to evaluate the performance of the PRSLM scheme. Simulation results show that the proposed scheme achieves 61.9% reduction in complex multiplication complexity, and 60.3% reduction in addition complexity compared with the COSLM scheme when the FFT size is 128. Furthermore, the proposed scheme achieves a similar PAPR reduction performance to the COSLM scheme without bit error rate degradation. In a nutshell, the PRSLM scheme improves noise tolerance and implementation efficiency of high-speed optical communication as well as alleviates nonlinear impairments.

Analysis of Peak to Average Power in the 5G NOMA-FBMC Waveform

Objectives: In this work, we investigate suitable techniques to reduce the Peak to Average Power Ratio (PAPR) for advanced modulation schemes in order to obtain better performance than current or commonly used modulation schemes for Fourth Generation (4G) and Fifth Generation (5G). Methods: The proposed scheme incorporates a combination of Selective Mapping (SLM) and Partial Transmission Scheme (PTS) and thereby efficiently minimizes the PAPR and the complexity of the framework. Further, it is seen that the proposed algorithm is crucial to achieving better spectral and power characteristics compared with the existing waveforms. Findings: The comparative results of the bit error rate (BER) and PAPR of the advanced SLM-PTS when applied to the OFDM, FBMC, NOMA, and NOMA-FBMC structures are shown, and it is found that the power and complexity are significantly decreased in the advanced waveforms, which makes the proposed algorithm efficient for the advanced waveforms. Novelty: A natural motivation for future modulation schemes is to harmoniously merge the newer modulation technique, Filter Bank Multi Carrier (FBMC), with the Non-Orthogonal Multiple Access (NOMA) framework. This has led to a recent modulation paradigm called FBMC-NOMA, wherein the NOMA power domain principle is applied to a group of FMBC modulated signals. The proposed SLM-PTS-based NOMA-FBMC structure efficiently enhances the throughput and PAPR performance for 5G and beyond 5G systems. Keywords: PAPR; FBMC; SLM; PTS; NOMA

A Construction Method of Phase Sequences for the Selected Mapping Scheme

In this paper, a construction method of phase sequences is proposed for the selected mapping (SLM) scheme. Three principles are applied to the construction process: periodicity, binary (±1), and maximization of the minimum Hamming distance between different sequences. Using the first and second principle, except the original frequency signal, the calculation process of other candidate time signals can be simplified as the linear addition of some intermediate signals, which are obtained in the inverse fast Fourier transform (IFFT) operation of the original frequency signal. Using the third principle, greater differences can be generated between different candidate signals, which is helpful to improve the peak-to-average power ratio (PAPR) reduction performance. Theoretical analysis and simulation results show that, with the help of new phase sequences, the SLM scheme can effectively reduce the computational complexity, while it shows almost the same performance of PAPR reduction as that of the traditional SLM scheme, whose phase sequences are from the odd row vectors in the Hadamard matrix.

PAPR Reduction in Optical OFDM Using Lexicographical Permutations With Low Complexity

Efficient utilization of the spectrum, increased resilience to inter-symbol interference (ISI) and simpler channel equalization are becoming important considerations in the design of wireless communication systems including visible light communication (VLC) systems. In this regard, orthogonal frequency division multiplexing (OFDM) has become a preferred modulation technique in wireless communication systems design. However, one of its major challenges is the high peak-to-average power ratio that leads to major inefficiencies. Symbol position permutation (SPP) is a distortion-less technique that achieves substantial PAPR reduction without BER degradation. However, the existing works focus on PAPR reduction using SPP for the radio frequency (RF) OFDM and the use of this technique in optical OFDM is not properly investigated. Therefore, in this paper, we present a new PAPR reduction technique based on lexicographical permutations called lexicographical symbol position permutation (LSPP) for PAPR reduction in direct current optical OFDM (DCO-OFDM). The proposed scheme is less complex than the conventional selective mapping (CSLM) scheme since there is no multiplication of the phase sequences with the DCO OFDM symbol to generate the candidate signals. We further introduce a new way of reducing the complexity by introducing a threshold PAPR and demonstrate that the complexity in terms of inverse fast Fourier transform (IFFT) operations can be reduced substantially depending on the selected threshold and the number of candidate signals.

Precoded SLM and PTS Scheme for Reduced PAPR in OFDM for Wireless Communications

Orthogonal Frequency Division Multiplexing (OFDM) contribute high data rates in current as well as future wireless communication systems but it aches from high Peak to Average Power Ratio (PAPR). But this high PAPR makes the High-Power Amplifier (HPA) complex which increases the cost of it and leads to the drawbacks like Inter Carrier Interference (ICI) and rise in out of band radiation. Even though many techniques are there to decrease the complexity of HPA by reducing the PAPR, Selected Mapping (SLM) and the Partial Transmit Sequence (PTS) provides less PAPR with low complexity. In this paper, both PTS and SLM are combined with Discrete Sine Transform (DST) and their PAPR and efficiencies are also compared with OFDM signal. The proposed hybrid DST-PTS and DST-SLM provides less PAPR compared to OFDM, SLM and PTS techniques with low complexity. Also, the bit error rate for DST-SLM and DST-PTS techniques are compared for different values of SNR. In future wireless communication systems, these proposed techniques can be used as they provide less bit error rate and less PAPR with low complexity

PAPR-Degraded Secure OFDM-WDM-PON Based on Chaotic Set-Partitioned SLM

This letter proposes and experimentally demonstrates an orthogonal frequency division multiplexing wavelength division multiplexing passive optical network (OFDM-WDM-PON) system based on novel chaotic set-partitioned selective mapping (SP-SLM) scheme. With the implementation of a three-dimensional chaotic system, peak-to-average power ratio (PAPR) reduction and chaotic encryption are simultaneously realized on the process of OFDM signal modulation, so as to enhance the system performance in the presence of PAPR, bit error rate (BER), fiber nonlinear tolerance and security. The experimental results show that, when compared with original OFDM signal, the OFDM signal with SP-SLM can achieve 4 dB PAPR reduction at the complementary cumulative distribution function value of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-4}$ </tex-math></inline-formula> , as well as a 1.1 dB gain in receiver sensitivity at a BER of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-3}$ </tex-math></inline-formula> . For fiber nonlinear tolerance, the optimal launch fiber power of OFDM signal with SP-SLM is 10 dBm, which is better than 9 dBm of original OFDM signal under the same received optical power of −16 dBm. Furthermore, the key space of the proposed scheme can reach up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{98}$ </tex-math></inline-formula> , which is large enough to effectively protect against illegal attackers.

Secure OFDM with Peak-to-Average Power Ratio Reduction Using the Spectral Phase of Chaotic Signals.

In this paper, a new physical layer security technique is proposed for Orthogonal Frequency Division Multiplexing (OFDM) communication systems. The security is achieved by modifying the OFDM symbols using the phase information of chaos in the frequency spectrum. In addition, this scheme reduces the Peak to Average Power Ratio (PAPR), which is one of the major drawbacks of OFDM. The Selected Mapping (SLM) technique for PAPR reduction is employed to exploit the random characteristics of chaotic sequences. The reduction with this algorithm is shown to be similar to that of other SLM schemes, but it has lower computational complexity and side information does not have to be sent to the receiver. The security of this technique stems from the noise like behavior of chaotic sequences and their dependence on the initial conditions of the chaotic generator (which are used as the key). Even a slight difference in the initial conditions will result in a different phase sequence, which prevents an eavesdropper from recovering the transmitted OFDM symbols.

Advanced SLM scheme based on discrete forest optimization algorithm for PAPR minimization in UFMC waveform

Inherent multicarrier transmission mechanism of the universal filtered multicarrier (UFMC) waveform engenders the problem of high peak-to-average power ratio (PAPR). Since it is impossible for a nonlinear high power amplifier (HPA) to execute a distortionless amplification unless the PAPR of transmission signal is below an acceptable level, eliminating the aforementioned PAPR drawback in UFMC waveform is so critical for smooth communication. With this in mind, we developed a new selective mapping (SLM) scheme based on discrete forest optimization algorithm (DFOA) for the UFMC waveform. The related scheme was created by embedding the DFOA into the conventional SLM with the intention of optimizing the values of phase factors by which the phase rotation process is carried out in frequency domain to reduce the PAPR of eventual time domain signal attained from the SLM output. It is confirmed via the simulations that, remarkable PAPR improvements are achieved through the DFOA-SLM scheme in the UFMC signal thanks to the DFOA-supported search for the optimal sequence of phase factors instead of classical random search strategy inherent in the conventional SLM method.

Selected‐Mapping Peak‐to‐Average Power Reduction Method with Orthogonal Pilot Sequences in Underwater Acoustic OFDM System Without Side Information

A novel Selected-mapping (SLM) Peak-to-average power ratio (PAPR) reduction scheme requires no Side information (SI) in Underwater acoustic (UWA) OFDM system is proposed. In the proposed scheme, every distinct phase sequence is represented by a unique Orthogonal comb pilot sequence (OPS), and the orthogonal properties of the OPSs are used to distinguish the index of phase sequences at the receiver. Therefore, the proposed scheme does not need to reserve bits for transmitting SI, so that the data rate can be raised. Simulation results show that the PAPR reduction performance has almost 0.5dB gains comparing to the Conventional SLM (C-SLM) scheme and the Bit error ratio (BER) performance is approximately the same as the SLM scheme with perfect SI. Field experimental results also demonstrate that the proposed scheme can differentiate phase sequences, therefore significantly enhance the quality of the UWA OFDM communication system.

PAPR reduction using selective mapping scheme in universal filtered multicarrier waveform

In this paper, the selective mapping (SLM) technique possessing the powerful and distortionless peak to average power ratio (PAPR) reduction capability was employed in universal filtered multicarrier (UFMC) waveform that is considered as one of the most promising fifth generation (5G) waveform candidates in order to provide a solution to the PAPR issue encountered in the related waveform. Owing to our SLM-based PAPR reduction implementation performed by employing the SLM scheme between the quadrate amplitude modulation (QAM) mapping and bandwidth-subdivision operations at the transmitter side, successful PAPR reduction results were achieved in a straightforward and effective manner. In the simulations, the effect of the related way of SLM application on alleviating the PAPR and spectral leakages of the UFMC signal amplified via the solid state power amplifier (SSPA) was investigated for various number of phase factor combinations. Besides, the impact of SLM on the bit error rate (BER) of the UFMC waveform was analyzed for varied values of SSPA parameters called smoothness (p) and input back off (IBO) controlling the linearity and operation point of the SSPA, respectively.

A SLM Scheme for PAPR Reduction in Polar Coded OFDM-IM Systems Without Using Side Information

In the present article, we propose a novel selected mapping (SLM) scheme based on a Polar coding technique for peak to average power ratio (PAPR) reduction in orthogonal frequency division multiplexing with index modulation (OFDM-IM) systems. The proposed scheme by utilizing random frozen bits in polar codes generates different number of candidate sequences. Then the candidate sequence with the smallest PAPR is selected for transmission. The proposed scheme can be considered as one block in an OFDM-IM system that performs both PAPR reduction and error correction. For a fair comparison, the performance of an OFDM-IM system based on the proposed scheme is compared with a system that carries out the same operations with two separate blocks where a Polar encoder is cascaded with the one for PAPR reduction (such as conventional SLM or PTS), and a Polar coded OFDM-IM system without any PAPR reduction scheme. Moreover, based on our proposed SLM scheme, a novel receiver without using side information (SI) is proposed. This SI free receiver is based on the successive cancellation list (SCL) polar decoding scheme. Simulation results show that as the Polar code can bring both error correction and PAPR reduction capabilities by using our proposed scheme. Also, the proposed SI free receiver can achieve similar bit error rate (BER) performance as that of the ideal case in both additive Gaussian white noise (AWGN) and frequency selective channels.

PAPR reduction of MIMO-OFDM system with reduced computational complexity SLM scheme

Multiple input and multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is a prominent technology for fourth generation mobile radio communication. OFDM is a special case of multi-carrier-modulation (MCM) technique that divides the high data rate input bit streams into large number of lower rate sub streams and each sub stream is transmitted over orthogonal subcarriers. The main advantage of MIMO-OFDM system is the efficient utilization of band width, multipath delay spread tolerance and mitigation of inter symbol interference (ISI) in frequency selective fading channels. However, the main drawback of MIMO-OFDM system is high peak to average power ratio (PAPR) for large number of sub carriers which causes serious degradation in performance. One of the well-known peak to average power ratio (PAPR) reduction schemes for MIMO-OFDM systems is selected mapping (SLM) scheme. In this work computational complexity of MIMO-OFDM system is reduced by adding mapping signal sequences to the OFDM signal sequences. It also increases the PAPR reduction performance of the MIMO-OFDM system.

Effective PAPR reduction in SCFDM‐based massive MIMO system using binary crow search algorithm for visible light communication towards 5G networks

Presently, the single-carrier frequency division multiplexing (SCFDM)-based visible light communication (VLC) system is extensively implemented for secure and high-speed data transmission. However, the effect of additive white Gaussian noise in VLC with white light-emitting diode is high, due to a high peak to average power ratio (PAPR). To address this difficulty in 5G networks, two objectives were carried out in this research article. Initially, selective mapping (SLM) scheme was applied for PAPR reduction, because it considerably selects the effective phase rotation factors that help in the reduction of system complexity. Besides, binary crow search algorithm was used for sub-block partition optimisation in SLM for enhancing the convergence speed of the proposed SCFDM-based VLC system. In the experimental investigation, the proposed SCFDM-based VLC system was analysed in terms of complementary cumulative distribution function, bit error rate and signal-to-noise ratio by varying the equalisation techniques for 5G networks.

A Novel Distributive Population-Based Differential Evolution Algorithm for SLM Scheme to Reduce PAPR in Massive MIMO-OFDM Systems

To achieve the ever rising demand for high data rates with high spectral efficiency, the energy efficient massive Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) will be essential and useful for future wireless communication systems as well as Industrial network applications to reduce the operational costs significantly. But the high Peak to Average Power Ratio (PAPR) in a massive MIMO-OFDM system is identified as a critical issue that causes the non-linear signal distortion and restricts the efficiency of the power amplifier. Among different PAPR reduction schemes, Selected Mapping (SLM) is a distortionless technique and highly attractive due to its simple implementation capability. However, the conventional SLM scheme is inefficient for the massive MIMO-OFDM antenna system for its enormous Side Information (SI) burden and large computational complexity to search the best set of phase factors. In this paper, a Distributive Population based Switching Differential Evolution strategy is incorporated in the SLM scheme which eventually enhances the searching ability. The algorithm is employed in different antenna grouping (homogeneous and heterogeneous) based massive MIMO systems. The antenna grouping concept in the massive MIMO system minimizes the SI burden. The proposed algorithm for SLM techniques outperforms the existing techniques in terms of PAPR, Bit Error Rate, SI burden, energy efficiency and computational complexity.

Combining partial transmit sequences and selective mapping to reduce computational complexity of selective mapping techniques

AbstractBoth selective mapping (SLM) and partial transmit sequences (PTSs) are multiple signal representation (MSR) techniques used to reduce the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Given the same number of candidate signals, SLM is superior to PTS in improving PAPR performance. However, SLM is associated with greater computational complexity, as more inverse discrete Fourier transforms (IDFTs) are required for SLM in comparison with PTS. To address this issue, this study proposes an improved SLM scheme, which divides available subcarriers into two parts, with one part used in PTS and the other in SLM. The proposed method determines whether PTS or SLM is to be used by input signals by setting an adaptive threshold, which can reduce the number of IDFTs accumulated over the implementation of SLM following a large number of OFDM signal transmissions. Statistical analysis of the simulation results show that after a large number of OFDM signals are transmitted, the proposed method not only reduces the number of IDFTs accumulated, but also allows each transmit signal to have PAPR‐reduction performance equivalent to that of conventional SLM schemes.