PAPR analysis in OTFS using the centre phase sequence matrix based PTS method

Orthogonal frequency division multiplexing (OFDM) is the advanced transmission scheme utilized in 4G. Nevertheless, it has several shortcomings like guard band, peak-to-average power ratio (PAPR), high power consumption, incapable to accommodate various other devices (an IOT application). Hence, OFDM cannot be considered in 5G due to the several disadvantages mentioned above. Filter bank multi-carrier (FBMC) is believed to be one of the most promising technologies which can be used in 5G. FBMC and OFDM are multi-carrier system. It is obvious that it agonizes from PAPR which hamper the efficiency of the system. The conventional peak reduction methods utilized in OFDM cannot be used in FBMC due to the overlapping structure of FBMC. In this work, a novel selective mapping (SLM) and partial transmit sequence (PTS) PAPR reduction technique is suggested for FBMC. The proposed techniques are implemented by using an elementary successive optimization technique that upsurge the PAPR performance and ensure the design difficulty is taken low. PAPR and bit error rate (BER) parameters are analyzed and simulated for the proposed and conventional PAPR reduction techniques. The simulation results show that the SLM and PTS accomplished an excellent PAPR reduction up to 2.8 and 4.8 dB as compared to other peak power minimization techniques.

In this study, the Peak-to-Average Power Ratio (PAPR) and Bit Error Rate (BER) performance in Orthogonal Time Frequency Space (OTFS) modulation with Non-Orthogonal Multiple Access (NOMA) over Rayleigh fading channels were investigated. Simulations with 256-QAM and 512-QAM modulation schemes on 256 subcarriers evaluated several PAPR reduction techniques, including the Vandermonde matrix-based Partial Transmit Sequence with Companding (Vm-PTS+Companding), Vm-SLM+Companding, conventional PTS, Selective Mapping (SLM), Companding, and Clipping & Filtering (C&F). The proposed Vm-PTS+Companding achieves up to 9dB PAPR reduction for 256-QAM and 8.9dB for 512-QAM at a Complementary Cumulative Distribution Function (CCDF) of [Formula: see text], outperforming existing methods. Under a [Formula: see text] channel estimation error, the PAPR performance degrades, yet the proposed scheme maintains a 2.9-9.9dB gain over conventional approaches. BER analysis showed Signal-to-Noise Ratio (SNR) improvements of 3.5-13.7dB in ideal channels and up to 16dB under error conditions. Power Spectral Density (PSD) evaluation further confirmed the reduced spectral leakage, with the method achieving a level of [Formula: see text]dB. These results demonstrate that Vm-PTS+Companding effectively optimizes both the PAPR and BER in OTFS-NOMA systems, supporting high data rates in error-prone wireless environments.

In this paper, we propose a new PAPR reduction by using a partial transmit sequences (PTS) method with coded side information (SI) technique. These methods are used in an orthogonal frequency division multiplexing (OFDM) system. The OFDM employs orthogonal sub-carriers for data modulation. These sub-carriers unexpectedly present a large peak to average power ratio (PAPR) in some cases. In order to reduce PAPR, the sequence of input data is partitioned into disjoint sub-block of PTS. If number of sub-block increases, high efficiency of PAPR reduction can be obtained. However, a quite large calculation cost must be demanded and thus it is impossible to obtain the optimum PTS. In the proposed method, we introduce a coded side information technique assuming the pseudo-optimum condition into the PTS. The total calculation cost becomes drastically reduced and side information bits for recovering original data in demodulation. In simulation results, the proposed method demonstrated the improvement of PAPR and bit error rate (BER) performance.

With the advent of 5G communications, the demand for high data rates and improved spectral efficiency has necessitated the exploration of advanced modulation techniques. Orthogonal Frequency Division Multiplexing (OFDM) and Universal Filtered Multi-Carrier (UFMC) are two prominent modulation schemes for 5G systems. However, both OFDM and UFMC suffer from a high Peak-to-Average Power Ratio (PAPR), leading to signal distortion and inefficient power amplification. The Partial Transmit Sequence (PTS) approach is a promising strategy to minimize PAPR in OFDM and is applied to UFMC to minimize PAPR in UFMC and is known as scrambled UFMC (S-UFMC). PTS, however, involves an extensive search to identify the best phase factors that increase computational complexity. The artificial bee colony algorithm is proposed to reduce the computational complexity S-UFMC and OFDM. A novel modulation scheme, amplitude phase shift keying (APSK), is used instead of quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) in S-UFMC and OFDM, which has better performance than conventional modulation schemes. In this research, OFDM, PTS OFDM, UFMC and S-UFMC are compared and it is found that the proposed scrambled UFMC with APSK modulation using ABC algorithm performs better than OFDM and UFMC in terms of PAPR, spectral efficiency and computational complexity.

This study presents a detailed performance evaluation of the proposed free space optical-orthogonal frequency division multiplexing (FSO-OFDM) system compared with conventional schemes such as orthogonal frequency division multiplexing (OFDM), filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and universal filtered multi-carrier (UFMC) under diverse optical channel conditions. Bit error rate (BER) results in Rayleigh fading channels indicate that the proposed method attains a BER of 10 −3 at only 6.2 dB Signal-to-Noise Ratio (SNR), yielding gains of 7.6 dB, 6.2 dB, 5.3 dB, and 3.4 dB over OFDM, FBMC, NOMA, and UFMC, respectively. In Rician fading channels, the same BER is achieved at just 5.4 dB SNR, with improvements of 7.2 dB, 5.8 dB, 4.8 dB, and 3.0 dB compared to the respective schemes. Peak-to-average power ratio (PAPR) analysis at a complementary cumulative distribution function (CCDF) of 10 −3 shows a value of 10.8 dB for the proposed system, reducing nonlinear distortions and improving amplifier efficiency. Capacity analysis confirms a peak of 300 units at 50 dB SNR, surpassing all competitors. Power spectral density (PSD) results reveal sidelobe suppression beyond −200 dBW/MHz, with significant out-of-band emission reductions. Overall, FSO-OFDM offers superior robustness, spectral efficiency, and throughput for high-capacity optical communication systems.

In this paper, a novel scheme of the weighted distortion-to-signal ratio (WDSR) based partial transmit sequence (PTS) is proposed to enhance the bit error rate (BER) performance in nonlinear distorted orthogonal frequency-division multiplexing (OFDM) systems, and its key idea is to employ the WDSR metric to predict the nonlinear distortion caused by high power amplifier (HPA). Furthermore, several alternative signals can be generated by the PTS technique, and the signal with the minimum WDSR is selected as the transmitted OFDM signal. Since the WDSR metric predicts the nonlinear distortion of OFDM systems, the BER performance of nonlinear distorted OFDM systems can be significantly improved. Simulation results show that the proposed WDSR-PTS scheme offers better BER performance than the conventional peak-to-average power ratio (PAPR) based PTS scheme.

In this paper, a novel cyclic constellation mapping method (CCM) is proposed to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. By properly choosing the move parameter, this method can obtain a considerable PAPR performance. Moreover, in order to demodulate the signal correctly at the receiver side, a pilot-aided estimation method is also introduced. Simulation results show that the proposed method achieves a better PAPR and bit-error rate (BER) performance than the conventional partial transmit sequences (PTS) while maintaining low computational complexity.

Orthogonal frequency division multiplexing (OFDM) based non-orthogonal multiple access (NOMA) systems can considerably increase the attainable data rate and spectral efficiency in novel communication systems. High peak-to-average power ratio (PAPR) is one of the main issues in OFDM-based systems. It makes high-power amplifier (HPA) work in the non-linear region and degrades system performance. Partial Transmit Sequences (PTS) based methods are one of the prominent schemes to reduce the PAPR value. However, they have high computational complexity, and they mostly degrade the system’s Bit Error Rate (BER) performance. In this paper, a low complexity PTS-based method, utilizing the dummy sequence insertion (DSI) technique and cyclic shift sequence (CSS) PTS, is proposed to overcome the previous limitations. Using numerical simulations, we will demonstrate that the proposed method outperforms similar ones in terms of PAPR reduction and BER performance with less computational complexity.

In this paper, we propose a genetic-simulated annealing algorithm (GSAA) with partial transmit sequence (PTS) technique (GSAA-PTS) to reduce the peak-to-average power ratio (PAPR) for orthogonal frequency division multiplexing (OFDM) system. Genetic algorithm based PTS method (GA-PTS) is a novel and suboptimal PAPR reduction approach, which has lower computational load than original PTS method. However, researchers still focus on how to improve the PAPR performance. The proposed method GSAA-PTS takes the advantages of genetic algorithm and simulated annealing algorithm to search the best phase factors of PTS. In this method, we initialize the population firstly, and then selection, crossover and mutation are used to generate the new population, finally using the simulated annealing algorithm to update each chromosome in the population. The simulation results show that the better performance of PAPR have been achieved by adopting GSAA-PTS scheme.

High Peak-to-Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) signal is one of the limitations to the transmission performance of optical OFDM system. In this paper, we propose a novel hybrid PAPR reduction technique called Hadamard Transform Combined with Partial transmit sequence (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and Partial Transmit Sequence (PTS), to improve the performance of the optical OFDM system in terms of PAPR and Bit Error Rate (BER). Simulation results show that the HTCP scheme has better performance with regard to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

In this paper, the partial transmit sequence (PTS) technique known as one of the most efficient peak to average power ratio (PAPR) reduction schemes is applied to the recently proposed fifth generation (5G) waveform candidate called universal filtered multicarrier (UFMC) for PAPR reduction process. Thanks to our way of application in which the PTS technique is employed before the process of subdividing the bandwidth into the number of sub-bands, the PAPR minimization is carried out in a very simple and efficient manner. In the simulations, the PAPR reduction performance of the PTS technique is analyzed for different search numbers (SNs). In addition, the effect of PTS on the power spectral density (PSD) and bit error rate (BER) performance of the UFMC system employing solid state power amplifier (SSPA) as a high power amplifier (HPA) is investigated for different input back off (IBO) and smoothness coefficient $(p)$ values.

Channel capacity and Peak Average to Power Ratio (PAPR) are essential elements in offering dependable communication through wireless medium in wireless communication system. The rating of an amplifier in an Orthogonal Frequency Division Multiplexing (OFDM) system, as well as prospective future candidates of 5G systems such as Filter Bank Multicarrier (FBMC) and Universal Filtered Multicarrier (UFMC), affected by a high peak to average power ratio. The demand for channel capacity fluctuates due to the growing number of wireless network users. This paper recommended a low PAPR FBMC method, showing excellent performance in terms of PAPR reduction gain, overhead computation complexity and overhead SI compared to the current PAPR reduction scheme. In order to further increase the reduction in PAPR we have developed four variants of FBMC waveforms for DFT expansion, ITSM and the selected with the smallest peak capacity. In order to further reduce the PAPR rate of DFT expansion we have produced four different versions. After implementation of the proposed algorithm, the PAPR of the FBMC method has been considerably reduced. Following use of DFT propagation and ITSM conditioning, PAPR was decreased by 25 percent. The side data, which is persistent with traditional PAPR reduction techniques like cutting, partial transmission series, and selective mapping, is also disabled. The proposed device improves the transmitters' lifetime and efficiency through waveform accuracy. The study begun was planned to reduce the limitations of contending waveforms in order to create a resourceful communication system.

The most widely used technique for high-data-rate transmission is orthogonal frequency division multiplexing (OFDM). However, one disadvantage of OFDM systems is that the transmitted signals have a high peak-to-average power ratio (PAPR). High PAPR causes more interference and lower resolution in analogue to digital (A/D) and digital to analogue (D/A) converters. In this paper, Partial Transmit Sequence (PTS) technique using Improved Harmony Search (IHS) algorithm is proposed to solve the high PAPR problem. The PTS technique has a high search complexity because it involves an extensive random search over all possible phase vector combinations, which grows exponentially with the number of phase vectors. IHS improves the accuracy and convergence rate of conventional algorithms while requiring only a few parameters to be adjusted. The modulation method used is Quadrature Phase Shift Keying (QPSK). The performance of PTS and IHS-PTS are analyzed using CCDF graphs with different values of subcarriers and iterations. The PAPR reduction percentage increases more with using IHS-PTS compared to PTS only. To conclude, implementing IHS together with PTS can improve computational complexity in PTS and helps to reduce PAPR values even better in OFDM system.KeywordsImproved Harmony Search (IHS)Orthogonal frequency division multiplexing (OFDM)Peak average power ratio (PAPR)Partial Transmit Sequence (PTS)

Terahertz (THz) integrated sensing and communication (ISAC) is a promising interdisciplinary technology that realizes simultaneously transmitting Terabit-per-second (Tbps) and millimeter-level accurate environment or human activity sensing. However, both communication performance and sensing accuracy are influenced by the Doppler effects, which are especially severe in the THz band. Moreover, peak-to-average power ratio (PAPR) degrades the THz power amplifier (PA) efficiency. In this paper, a discrete Fourier transform spread orthogonal time frequency space (DFT-s-OTFS) system with superimposed pilots is proposed to improve the robustness to Doppler effects and reduce PAPR for THz ISAC. Then, a two-phase sensing parameter estimation algorithm is developed to integrate sensing functionality into the DFT-s-OTFS waveform. Meanwhile, a low-complexity iterative channel estimation and data detection method with a conjugate gradient based equalizer is proposed to recover the data symbols of DFT-s-OTFS. The proposed DFT-s-OTFS waveform can improve the PA efficiency by 10% on average compared to OTFS. Simulation results demonstrate that the proposed two-phase sensing estimation algorithm for THz DFT-s-OTFS systems is able to realize millimeter-level range estimation accuracy and decimeter-per-second-level velocity estimation accuracy. Moreover, the effectiveness of the iterative method for data detection aided by superimposed pilots in DFT-s-OTFS systems is validated by the simulations and the bit error rate performance is not degraded by the Doppler effects.

Orthogonal Frequency Division Multiplexing (OFDM) has several desirable attributes, such as high immunity to inter-symbol interference, robustness with respect to multi-path fading, and ability for high data rates, all of which are making OFDM to be incorporated in wireless standards like IEEE 802.11a/g/n WLAN and ETSI terrestrial broadcasting. However one of the major problems posed by OFDM is its high Peak-to-Average-Power Ratio (PAPR), which seriously limits the power efficiency of the transmitter’s High Power Amplifier (HPA). This is because PAPR forces the HPA to operate beyond its linear range with a consequent nonlinear distortion in the transmitted signal. One of good solutions to mitigate this nonlinear distortion is put a Pre-Distorter before the High Power Amplifier and increase linear dynamic range up to a saturation region (1) (2) (3). However, the main disadvantage of Pre-Distorter technique is that these PD techniques only work in a limited range, that is, up to the saturation region of the amplifier. In this situation, Peak-to-Average Power Ratio (PAPR) reduction techniques which pull down high PAPR of OFDM signal to an acceptable range can be a good complementary solution. Due to practical importance of this, there are various PAPR reduction techniques for OFDM signals (4) (5) (6) (7) (8) (9). Among them, the PTS (Partial Transmit Sequence) technique is very promising because it does not give rise to any signal distortion (9). However, its high complexity makes it difficult to use in a practical system. To solve the complexity problem of the PTS technique, Cimini and Sollenberger proposed an iterative flipping algorithm (10). Even though the iterative flipping algorithm greatly reduces the complexity of the PTS technique, there is still some performance gap between the ordinary PTS and the iterative flipping algorithm. In this chapter, we propose an enhanced version of the iterative flipping algorithm to reduce the performance gap between the iterative flipping algorithm and the ordinary PTS technique. In the proposed algorithm, there is an adjustable parameter to allow a performance/complexity trade-off.