Partial Transmit Sequence Research Articles

A Comparative Analysis of WiMax System with Partial Transmit Sequence (PTS) and Low Complexity PTS

A Comparative Analysis of WiMax System with Partial Transmit Sequence (PTS) and Low Complexity PTS

On the Shift Value Set of Cyclic Shifted Sequences for PAPR Reduction in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) signals have high peak-to-average power ratio (PAPR), which causes distortion when OFDM signal passes through a nonlinear high power amplifier. A partial transmit sequence (PTS) scheme is one of the typical PAPR reduction methods. A cyclic shifted sequences (CSSs) scheme is evolved from the PTS scheme to improve the PAPR reduction performance, where OFDM signal subsequences are cyclically shifted and combined to generate alternative OFDM signal sequences. The shift value (SV) sets in the CSS scheme should be carefully selected because those are closely related to the PAPR reduction performance of the CSS scheme. In this letter, we propose some criteria to select the good SV sets and verify its validness through simulations.

Low‐complexity PTS schemes using OFDM signal rotation and pre‐exclusion of phase rotating vectors

Partial transmit sequence (PTS), a well-known peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) systems, has been actively investigated to reduce its high computational complexity. Ku et al. proposed a selection method of dominant time-domain samples and by only using the selected samples, the PAPR of each alternative OFDM signal vector is calculated. This method clearly reduces the computational complexity but it is crucial to select proper time-domain samples to achieve acceptable PAPR reduction performance. In this study, a new selection method of dominant time-domain samples is proposed based on rotating samples of inverse fast Fourier transformed (IFFTed) subblocks to the local area on which the corresponding sample of the IFFTed first subblock is located. Moreover, pre-exclusion of phase rotating vectors based on the above time-domain sample rotation is proposed to further reduce the computational complexity. Numerical results confirm that the proposed PTS schemes substantially reduce the computational complexity with negligible degradation of PAPR reduction performance.

Partial Transmit Sequence Based Cuckoo Search Optimization for Peak-to-Average Power Ratio Reduction in Orthogonal Frequency Division Multiplexing Systems

Partial Transmit Sequence Based Cuckoo Search Optimization for Peak-to-Average Power Ratio Reduction in Orthogonal Frequency Division Multiplexing Systems

A novel generalized oppositional biogeography-based optimization algorithm: application to peak to average power ratio reduction in OFDM systems

Abstract A major drawback of orthogonal frequency division multiplexing (OFDM) signals is the high value of peak to average power ratio (PAPR). Partial transmit sequences (PTS) is a popular PAPR reduction method with good PAPR reduction performance, but its search complexity is high. In this paper, in order to reduce PTS search complexity we propose a new technique based on biogeography-based optimization (BBO). More specifically, we present a new Generalized Oppositional Biogeography Based Optimization (GOBBO) algorithm which is enhanced with Oppositional Based Learning (OBL) techniques. We apply both the original BBO and the new Generalized Oppositional BBO (GOBBO) to the PTS problem. The GOBBO-PTS method is compared with other PTS schemes for PAPR reduction found in the literature. The simulation results show that GOBBO and BBO are in general highly efficient in producing significant PAPR reduction and reducing the PTS search complexity.

Performance Analysis of PAPR Reduction in 4×4 Spatially Multiplexed MIMO-OFDM System using SLM and Optimum-PTS Techniques

Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising candidate for 4G high-data-rate broadband wireless communications. However, MIMO-OFDM inherited the problem of high Peak-to-Average Power Ratio (PAPR) from OFDM which leads to in-band distortion, undesired spectral spreading, low power efficiency and increases the cost of the RF power amplifier. Many PAPR reduction techniques were developed in last two decades to reduce the PAPR of OFDM, among them Partial Transmit Sequence (PTS) and Selected Mapping (SLM) are the important ones. This paper proposes two PAPR reduction technique; SLM and Optimum -PTS for reducing the PAPR and does performance comparison of these two techniques on the basis of reduction in PAPR level, BER and the number of redundant bits required. It shows that the use of Optimum-PTS technique with QPSK modulation comprising of 128 subcarriers provides better PAPR reduction and good BER as compared to SLM.

PAPR reduction using genetic algorithm in lifting-based wavelet packet modulation systems

Wavelet packet modulation (WPM) is a potential candidate in wireless communication systems by virtue of its exibility and modular implementation capability. However, WPM suffers from high peak-to-average power ratio (PAPR), which results in signal distortion when a high-power amplier is employed at the transmitter. The partial transmit sequence (PTS) is an attractive PAPR reduction method, but its computational complexity is high. In this paper, we propose a PTS based on the genetic algorithm (GA) scheme (GA-PTS) to reduce the computational complexity of the PTS in the lifting-based WPM (LBWPM) systems. Simulation results show that the proposed GA-PTS scheme provides signicant improvement in PAPR reduction while maintaining a low computational load. The cumulative distribution function performance of the LBWPM system is better than the performance of the classical WPM.

Hybrid PAPR Reduction Scheme for FBMC/OQAM Systems Based on Multi Data Block PTS and TR Methods

The filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is being studied by many researchers as a key enabler for the fifth-generation air interface. In this paper, a hybrid peak-to-average power ratio (PAPR) reduction scheme is proposed for FBMC/OQAM signals by utilizing multi data block partial transmit sequence (PTS) and tone reservation (TR). In the hybrid PTS-TR scheme, the data blocks signal is divided into several segments, and the number of data blocks in each segment is determined by the overlapping factor. In each segment, we select the optimal data block to transmit and jointly consider the adjacent overlapped data block to achieve minimum signal power. Then, the peak reduction tones are utilized to cancel the peaks of the segment FBMC/OQAM signals. Simulation results and analysis show that the proposed hybrid PTS-TR scheme could provide better PAPR reduction than conventional PTS and TR schemes in FBMC/OQAM systems. Furthermore, we propose another multi data block hybrid PTS-TR scheme by exploiting the adjacent multi overlapped data blocks, called as the multi hybrid (M-hybrid) scheme. Simulation results show that the M-hybrid scheme can achieve about 0.2-dB PAPR performance better than the hybrid PTS-TR scheme.

An Enhanced Partial Transmit Sequence Segmentation Schemes to Reduce the PAPR in OFDM Systems

Although the orthogonal frequency division multiplexing system (OFDM) is widely used in high-speed data rate wire and wireless environment, the peak-to- average-power-ratio (PAPR) is one of its major obstacles for the real applications. The high PAPR value leads some devices of the OFDM system such as power amplifiers and analog to digital converters to work out of band of these devices. Thus the system efficiency is degraded. Many techniques have been proposed to overcome the high PAPR in OFDM systems such as partial transmit sequences (PTS), selected mapping and interleaving technique. PTS is considered as one of the effective PAPR reduction methods; this scheme depends on segmentation of the input data into several subblocks and then combined again. The three well-known segmentation schemes are pseudo-random, adjacent and interleaving; each scheme has PAPR reduction performance, and computational complexity differs from one to another. In this paper, five types of segmentation schemes are proposed to improve the PAPR reduction execution including sine and cosine shape as well as hybrid interleaving and adjacent schemes in new approaches. From the simulation results, the proposed methods can achieve PAPR reduction performance greater than that of the adjacent and interleaving partition schemes, without increasing the computational complexity of the system. Moreover, the enhanced schemes can realize better PAPR performance with any number of subcarriers.

Peak-to-Average Power Ratio Reduction based Varied Phase for MIMO-OFDM Systems

One of the severe drawbacks of orthogonal fre-quency division multiplexing (OFDM) is high Peak-to-Average Power Ratio (PAPR) of transmitted OFDM signals. During modulation the sub-carriers are added together with same phase which increases the value of PAPR, leading to more interference and limits power efficiency of High Power Amplifier (HPA), it’s requires power amplifier’s (PAs) with large linear oper-ating ranges but such PAs are difficult to design and costly to manufacture. Therefore, to reduce PAPR various methods have been proposed. As a promising scheme, partial transmit sequences (PTS) provides an effective solution for PAPR reduction of OFDM signals. In this paper, we propose a PAPR reduction method for an OFDM system with variation of phases based on PTS schemes and Solid State Power Amplifiers (SSPA) of Saleh model in conjunction with digital predistortion (DPD), in order to improve the performance in terms of PAPR, the HPA linearity and for the sake of mitigating the in-band distortion and the spectrum regrowth. The simulation results show that the proposed algorithm can not only reduces the PAPR significantly, but also improves the out-of-band radiation and decreases the computational complexity.

Hybrid PAPR Reduction Scheme with Partial Transmit Sequence and Tone Reservation for FBMC/OQAM

Hybrid PAPR Reduction Scheme with Partial Transmit Sequence and Tone Reservation for FBMC/OQAM

PAPR and PICR Reduction of OFDM Signals with Clipping Noise-based Tone Injection Scheme

Orthogonal frequency-division multiplexing (OFDM) suffers from a high peak-to-average power ratio (PAPR). Tone injection (TI) extends the original constellation to several equivalent points so that these extra freedom degrees can be exploited for the PAPR reduction. However, optimal TI requires an exhaustive search over all possible constellations, which is a hard discrete optimization problem. To address this problem, a novel TI scheme that uses the clipping noise to find the optimal equivalent outer ring extended constellations (ECs) and hexagonal constellations (HCs) is proposed. By minimizing the mean rounding error of the clipping noise and possible equivalent constellations, the proposed scheme can easily determine the size and position of the optimal equivalent constellations. Second, a new TI scheme is also introduced to reduce the nonlinear distortion in the presence of a power amplifier (PA). This scheme takes the root-mean-square peak-interference-to-carrier-ratio (RMS-PICR) reduction as the target to obtain a better bit error rate (BER) performance. Simulation results show that, to achieve a considerable system performance, the proposed TI schemes only need 18 fast Fourier transforms (FFTs), whereas other TI and partial transmit sequence (PTS) schemes need hundreds of FFTs.

Peak-to-average power ratio reduction using backtracking search optimization algorithm in OFDM systems

A peak-to-average power ratio (PAPR) reduction method for an orthogonal frequency division multiplexing (OFDM) system based on a combination of a partial transmit sequence (PTS) scheme with the backtracking search optimization algorithm (BSA) is proposed. The PTS scheme shows good PAPR reduction performance; however, it requires a complex computation to search the set of optimum phase factors, especially for high-speed data transmissions. To minimize the complexity of the search for optimum phase factors, the PTS scheme is combined with the BSA. The BSA is a new and efficient population-based evolutionary search algorithm for real-valued optimization problems. A set of simulations is conducted for the PAPR reduction performance and computational complexity comparisons of the BSA-PTS scheme with different PTS schemes. Simulation results indicate that the BSA-PTS scheme yields an effective PAPR reduction performance with low computational complexity.

On the Comparative Performance Analysis of PAPR Reduction Techniques in OFDM System

Selected Mapping (SLM) and Partial Transmit Sequence (PTS) are two very well-known Peak-to-average Power Ratio (PAPR) reduction techniques for Orthogonal Frequency Division Multiplexing (OFDM) systems. Both these schemes show good PAPR reduction capabilities. However, for any PAPR reduction technique, the nature of spectral occupancy and the associated computational complexity also need to be taken into account when the overall performance is considered. In this paper, our goal is to perform a comparative performance analysis of SLM and PTS techniques by considering these three parameters, i.e. PAPR reduction, computational overhead and spectral compactness. For this, we at first look for the optimum values in terms of number of sequences in SLM and no. of sub-blocks in PTS. And then based on this finding, we perform performance analysis. Our finding shows that, PTS outperforms SLM when compared on the parameters mentioned above. Finally, to explore the feasibility of further improvement, we apply Walsh-Hadamard Transform to PTS scheme and show that it further reduces PAPR and improves spectral compactness.

Peak to average power ratio reduction in OFDM system using hybrid technique

There are many benefits of utilizing OFDM like robustness and high spectral efficiency against ISI but still there are some disadvantages. The main problem that arises in OFDM systems is high PAPR. There are many techniques available for reduction of PAPR like tone reservation (TR), clipping and filtering, partial transmit sequence (PTS), active constellation scheme, interleaving and selected mapping (SLM). Clipping and filtering are the easiest techniques but they are not suitable when large number of sub-carriers are present. The most common techniques used for PAPR reduction are PTS and SLM. PTS and SLM algorithms have achieved good performance in PAPR reduction. A new method is proposed in this paper which is hybrid combination of PTS and SLM and this method has also reduced the PAPR from 6 to 5. The results are compared with the already available techniques and this method achieves better results.

Chaos-Based Partial Transmit Sequence Technique for Physical Layer Security in OFDM-PON

We propose and demonstrate a physical layer security scheme via chaotic partial transmit sequence (PTS) technique in orthogonal frequency-division multiplexing passive optical network (OFDM-PON). A 4-D hyper chaos is employed to generate the chaotic partition information, the chaotic phase weighing factors in PTS as well as the chaotic training sequence for OFDM symbol synchronization, which provides a huge key space to enhance the physical layer confidentiality. Transmission of 8.9-Gb/s 16 quadrature amplitude modulation encrypted OFDM signals is demonstrated over 20-km standard single-mode fiber, which shows reliable robustness against exhaustive attacks. Moreover, the proposed scheme improves the OFDM transmission performance due to the effective reduction of the peak-to-average power ratio of the OFDM signals by chaotic random PTS.

A Modified Shuffled Frog Leaping Algorithm for PAPR Reduction in OFDM Systems

Significant reduction of the peak-to-average power ratio (PAPR) is an implementation challenge in orthogonal frequency division multiplexing (OFDM) systems. One way to reduce PAPR is to apply a set of selected partial transmission sequence (PTS) to the transmit signals. However, PTS selection is a highly complex NP-hard problem and the computational complexity is very high when a large number of subcarriers are used in the OFDM system. In this paper, we propose a new heuristic PTS selection method, the modified chaos clonal shuffled frog leaping algorithm (MCCSFLA). MCCSFLA is inspired by natural clonal selection of a frog colony, it is based on the chaos theory. We also analyze MCCSFLA using the Markov chain theory and prove that the algorithm can converge to the global optimum. Simulation results show that the proposed algorithm achieves better PAPR reduction than using others genetic, quantum evolutionary and selective mapping algorithms. Furthermore, the proposed algorithm converges faster than the genetic and quantum evolutionary algorithms.

A Low‐Complexity PTS Based on Greedy and Genetic Algorithm for OFDM Systems

Partial transmit sequence (PTS) is one of effective technique to reduce high Peak-to-average power ratio (PAPR) in Orthogonal frequency division multiplex- ing (OFDM) system. However, the complexity of Original PTS (O-PTS) increases exponentially with the number of sub-blocks. To reduce the computational complexity while still offering a lower PAPR, a new PTS method is pro- posed to search for suboptimal rotating vectors in this pa- per. In the proposed method, the candidate rotation vec- tors are generated based on greedy and genetic algorithm. We also combine the proposed method and the superim- posed training sequence method to get a further PAPR reduction. The theory and simulations results show that the proposed method can achieve better PAPR reduction and significantly reduce the computational complexity.

Reduction of PAPR in OFDM Signals by using Electromagnetism Optimization Algorithm

Orthogonal Frequency Division Multiplexing grown to be a trendy modulation process inside impressive tempo wirelesscommunications. It is more advantageous over remaining technologies, even though it has some problems also. The high PAPR (Peak toAverage Power Ratio) is the main difficulty which causes non linearity at the receiving end. To reduce the PAPR so many techniques areproposed in previous such as clipping and filtering, SLM, CE, SA, PTS and so on. PTS (Partial Transmit Sequence) is highly successive thananother. In this paper PTS technique is used to reduce the PAPR but there is one problem with PTS technique, it introduces a high amount of complexity. So that to reduce such complexity and get better PAPR we planned to implement a novel based stochastic optimization algorithm which is EM (Electromagnetism-like) algorithm. By using EM get the better PAPR than PTS

A novel TS-EIA-PTS PAPR reduction algorithm for optical OFDM systems

Because the partial transmit sequence (PTS) peak-to-average power ratio (PAPR) reduction technology for optical orthogonal frequency division multiplexing (O-OFDM) systems has higher computational complexity, a novel two-stage enhanced-iterative-algorithm PTS (TS-EIA-PTS) PAPR reduction algorithm with lower computational complexity is proposed in this paper. The simulation results show that the proposed TS-EIA-PTS PAPR reduction algorithm can reduce the computational complexity by 18.47% in the condition of the original signal sequence partitioned into 4 sub-blocks at the remaining stage of n-d=5. Furthermore, it has almost the same PAPR reduction performance and the same bit error rate (BER) performance as the EIA-PTS algorithm, and with the increase of the subcarrier number, the computational complexity can be further reduced. As a result, the proposed TS-EIA-PTS PAPR reduction algorithm is more suitable for the practical O-OFDM systems.