Good Peak-to-average Power Ratio Reduction Performance Research Articles

Comparison of PAPR Reduction Using ABC-FF Algorithm and OGWO in MIMO-OFDM

In the transmitted signal, the high peak-to-average power ratio (PAPR) is the real disadvantage of multiple input, multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Among different PAPR reduction techniques, selected mapping (SLM) is a famous strategy that accomplishes good PAPR reduction performance without signal distortion. Likewise, Partial transmit sequence (PTS) is additionally solitary of the successful techniques to decrease the PAPR in OFDM. Though, result an optimal segment issue in PTS system is measured to exist a critical concern. To progress the existing PAPR reduction techniques, we have incorporated ideal SLM and PTS based PAPR reduction strategy in parallel. By utilizing, the OGWO algorithm; the transmit succession was chosen with least PAPR above all communication antennas. The proposed PAPR reduction approach is applied independently on each transmitted antenna, and so the PAPR can be extremely reduced. Moreover, the OGWO optimization based PAPR reduction technique will provide better performance and it was been promoted as an uncomplicated way for PAPR reduction. The proposed approach will be analyzed with ABC-FF Algorithm PAPR reduction scheme to show the effectiveness

A modified Hadamard based SLM without side information for PAPR reduction in OFDM systems

High peak-to-average power ratio (PAPR) is a concern in orthogonal frequency division multiplexing (OFDM) systems. Hadamard based selected mapping (HSLM) which uses Hadamard code as the phase sequence in selected mapping (SLM) is an attractive technique to reduce PAPR. But it requires sending side information (SI) to the receiver for each data block, and this results in a reduction in bandwidth efficiency. In this paper, we proposed a modified PAPR reduction method called semi-Hadamard based selected mapping (semi-HSLM) to decouple the phase information matrix into a phase rotation matrix for PAPR reduction and a SI matrix for side information hiding. We proposed a semi-hadamard matrix generation method to generate the phase rotation matrix, and designed a cyclic shift matrix as the SI matrix. Compared with the traditional HSLM, the semi-HSLM saves half of the phase storage and achieves good PAPR reduction performance.

PAPR Reduction in OFDM Systems Using Modified SLM with Different Phase Sequences

High Peak-to-average power ratio (PAPR) is one of the main issues in multicarrier modulation systems. PAPR is mainly caused due to the summation of various signals having high amplitude values. Several PAPR reduction techniques were employed, out of which Selective Mapping (SLM) proved to be one of the most effective schemes. Some drawbacks in SLM technique are high computational complexity and phase search complexity. Selection of phase sequences in SLM plays a major role in the reduction of PAPR as well as the computational complexity. Modified SLM was introduced to reduce computational complexity in SLM technique. In this paper, we apply various phase sequences such as Riemann, Centering, Centered Riemann and New Centered to Modified SLM technique and their effect on PAPR reduction are analyzed. From the simulation results, it can be inferred that the modified SLM with New Centered scheme achieves a significant PAPR reduction of the range 8.3–9.3 dB with respect to Conventional OFDM and 3–5.5 dB with respect to Conventional SLM technique. The Modified SLM-New Centered scheme is most suitable for 64-QAM applications as it provides good PAPR reduction performance at lower computational complexity.

Peak Average Power Ratio Reduction Technique For Better Performance With Multi Input Multi Output

In the transmitted signal, the high peak-to-average power ratio (PAPR) is the real disadvantage of multiple input, multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Among different PAPR reduction techniques, selected mapping (SLM) is a famous strategy that accomplishes good PAPR reduction performance without signal distortion. Likewise, Partial transmit sequence (PTS) is additionally solitary of the successful techniques to decrease the PAPR in OFDM. Though, result an optimal segment issue in PTS system is measured to exist a critical concern. To progress the existing PAPR reduction techniques, we have incorporated ideal SLM and PTS based PAPR reduction strategy in parallel. By utilizing, the OGWO algorithm; the transmit succession was chosen with least PAPR above all communication antennas. The proposed PAPR reduction approach is applied independently on each transmitted antenna, and so the PAPR can be extremely reduced. Moreover, the OGWO optimization based PAPR reduction technique will provide better performance and it was been promoted as an uncomplicated way for PAPR reduction. The proposed approach will be analyzed with various novel PAPR reduction schemes to show the effectiveness.

Improved Tone Reservation PAPR Reduction Algorithm in NC-OFDM/OQAM System

Non-continuous orthogonal frequency division multiplexing with offset quadrature amplitude modulation (NC-OFDM/OQAM) is often referred to overcome the issues associated with spectrum distribution. The corresponding peak to average power ratio (PAPR) emerged as a difficult task for the hardware implementation which seriously restricts the practicability of NC-OFDM/OQAM. To solve this problem, an improved PAPR reduction algorithm based on the tone reservation technique is proposed. According to the results of spectrum sensing, the bands are divided into two categories based on whether or not there are primary users (PU). Secondary users (SU) choose different sub-carrier numbers and amplitudes of the reserved sub-carriers in those bands separately. There by, SU get a substantial PAPR reduction while avoiding the interference to the PU and increasing the spectrum utilization efficiency. Theoretical analysis and simulation results show that the proposed algorithm supports a good PAPR reduction performance and efficient use of spectrum as well.

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.

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.

PAPR Analysis of Class-III SLM Scheme Based on Variance of Correlation of Alternative OFDM Signal Sequences

Selected mapping (SLM) is a well-known peak-to-average power ratio (PAPR) reduction technique for orthogonal frequency division multiplexing (OFDM) systems. Recently, a low-complexity SLM scheme, called Class-III SLM scheme, was proposed, which performs only one inverse fast Fourier transform (IFFT) to generate alternative OFDM signal sequences. By randomly selecting the cyclic shift and rotation values, Class-III SLM scheme can generate up to $N^{3}$ alternative OFDM signal sequences, where $N$ is the IFFT size. However, all $N^{3} $ alternative OFDM signal sequences do not achieve good PAPR reduction performances. Therefore, an efficient selection method of good rotation and cyclic shift values is needed, which results in good PAPR reduction performance.

Partial phase weighting selected mapping scheme for peak‐to‐average power ratio reduction in orthogonal frequency division multiplexing system

As one of the most attractive schemes, selected mapping (SLM) provides an effective solution for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) system. However, in conventional SLM (CSLM), the large number of inverse fast Fourier transform (IFFT) operations are required for achieving the satisfactory PAPR reduction performance, which results in the large computational complexity. In this study, a partial phase weighting SLM (PPW-SLM) for PAPR reduction in OFDM system is proposed. In the proposed PPW-SLM, partial phase weighting method and the properties of IFFT are employed for simplifying the calculations of IFFTs and obtaining good PAPR reduction performance. Theoretical analysis and simulation results show that, compared with CSLM, the proposed PPW-SLM can obtain a significant computational complexity reduction in similar PAPR reduction performance.

PTS Method with Combined Partitioning Schemes for Improved PAPR Reduction in OFDM System

Although orthogonal frequency division multiplexing (OFDM) is an efficient wireless transmission system, it suffers from a crucial drawback namely high peak-to-average power ratio (PAPR) that limits transmitter power efficiency. Thus, different PAPR reduction algorithms have been introduced. Partial transmit sequence (PTS) is the most attractive solution which can provide good PAPR reduction performance without distortion. In any PTS system, partitioning of the OFDM frame into disjoint sub-blocks is a significant step. Out of the existing partitioning techniques, adjacent partitioning (AP) is a fairly simple partitioning scheme achieving efficient PAPR reduction performance. This paper presents an enhanced PTS approach that combines two PTS partitioning schemes, adjacent and interleaved partitioning, in order to effectively reduce the PAPR of OFDM systems. With an aim of determining the effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with the enhanced PTS scheme.

Swapped SLM scheme for reducing PAPR of OFDM systems

The selected mapping (SLM) scheme is a competent method for reducing the high peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. One drawback of the conventional SLM (C-SLM) scheme is the high computational complexity. To reduce the complexity of C-SLM, the real and imaginary parts of the OFDM signals are treated separately. The even and odd sequences of the real and imaginary parts are obtained using the Fourier transform properties. More candidates are generated by the different combination of all the sub-sequences. The proposed scheme has a lower computational complexity using only M inverse fast Fourier transform (IFFT) operations to generate M4 candidates. The simulation results show that the proposed scheme achieves good PAPR reduction performance and also reduces the computational complexity significantly compared with the C-SLM scheme.

Peak-to-Average Power Ratio Reduction of OFDM Signals by Applying Low Complexity SLM and Clipping Hybrid Scheme

This paper presents performance analysis of Peak to Average Power Ratio (PAPR) Reduction techniques in Orthogonal Frequency Division Multiplexing (OFDM) System such as Clipping, Partial Transmit Sequence (PTS), Selective Mapping (SLM) and SLM with Clipping (Hybrid Scheme) .Complementary Cumulative Distribution Function (CCDF) is calculated for each technique with different number of sub carriers in order to analyze PAPR reduction performance and also compared with pure OFDM signal. According to our simulation results, SLM with clipping (Hybrid) technique has good PAPR reduction performance than other conventional methods, with less computational complexity.

A New Low-Complexity PTS Scheme Based on Successive Local Search Using Sequences

A new partial transmit sequence (PTS) scheme with low computational complexity is proposed, where two search steps are taken to find a subset of phase rotating vectors showing good peak-to-average power ratio (PAPR) reduction performance. In the first step, sequences with low correlation are used as phase rotating vectors for PTS scheme, which are called the initial phase vectors. In the second step, local search is performed based on the initial phase vectors to find additional phase rotating vectors which show good PAPR reduction performance. Numerical analysis shows that the proposed PTS scheme achieves better PAPR reduction performance with significantly reduced computational complexity than the existing low-complexity PTS schemes.

Selected basis for PAR reduction in multi-user downlink scenarios using lattice-reduction-aided precoding

The application of OFDM within a multi-user downlink scenario is considered. Thereby, two problems occur. First, due to OFDM, the transmit signal exhibits a large peak-to-average power ratio (PAR). Second, the multi-user interferences have to be equalized (or precoded) at the transmitter side. In this article, we address combined precoding and PAR reduction. As precoding schemes sorted Tomlinson-Harashima precoding (sTHP) and its lattice-reduction-aided variant (LRA-THP) are considered. In order to reduce the PAR, we review the scheme selected sorting (SLS), which is a combined approach of PAR reduction and precoding with sTHP. Based on this idea, the novel PAR reduction scheme selected basis (SLB) is introduced which combines PAR reduction with the precoding approach LRA-THP. It can be shown that SLB achieves very good PAR reduction performance and hardly influences the error performance. Both schemes, SLB and SLS, are compared with simplified selected mapping (sSLM), the only PAR reduction scheme from the SLM family, which can be applied in multi-user downlink scenarios. The comparison is done on the basis that the respective schemes exhibit the same computational complexity. In terms of PAR reduction performance, it turns out that sSLM outperforms SLS, whereas the performance of sSLM and SLB is similar. Noteworthy, the great benefit of SLB or SLS is that no side information has to be communicated to the receiver as it is necessary with sSLM. Moreover, using SLB, full diversity error rate performance is possible with only low-PAR transmit signals.

NC-OFDM 기반 통신 시스템에서 효율적인 Comb Type Pilot 배치 방식과 PAPR 저감 기법

NC-OFDM(Non-Contiguous Orthogonal Frequency Division Multiplexing) 기반의 무선 통신 시스템은 많은 부반송파의 수로 인해 높은 PAPR(Peak-to-Average Power Ratio)을 갖는다. Comb type pilot은 시변 채널 추정에 있어서 block type pilot보다 낮은 계산 복잡도를 가지며 더 효율적이다. 그러나 CAZAC(Constant Amplitude Zero Auto-Correlation) 행렬 변환이 뛰어난 PAPR 저감 효과를 보임에도 불구하고, comb type pilot이 데이터 심볼에 삽입되게 되면 PAPR이 다시 증가하는 문제가 있다. 따라서, 본 논문에서는 이러한 comb type pilot 배치로 인해 증가된 PAPR을 개선하기 위해 추가적으로 새로운 방식의 SLM(Selective Mapping)을 적용하였다. 또한, 본 논문에서 사용된 새로운 방식의 SLM 기법은 일반적인 SLM 기법과 달리, SLM의 선택 정보를 전송하기 위한 추가적인 대역폭을 사용하지 않음으로써 대역 효율을 높인다. 따라서, 본 논문에서 제안된 시스템은 제한된 주파수 대역을 이용하여 고효율의 데이터 전송을 얻을 수 있다. Because of a large number of subcarriers, the high PAPR(Peak-to-Average Power Ratio) is the major drawback of NC-OFDM system used for wireless communication system. Comb type pilot assignment is more efficient and lower computational complexity for the channel estimation than the block type pilot. However, even if the CAZAC(Constant Amplitude Zero Autocorrelation) matrix transform is used for the PAPR reduction of the data symbols, PAPR increases when the pilot is inserted in comb type with the data symbols. Therefore, in this paper, we additionally use a new SLM technique in order to lower the PAPR again even in the comb type pilot. Also, a new SLM technique suggested in this paper does not need any additional bandwidth for sending selection information for SLM. This combined method has good PAPR reduction performance and efficient data transmission.

Performance Analysis of the Clipping Scheme with SLM Technique for PAPR Reduction of OFDM Signals in Fading Channels

Since one of major problems of OFDM-based systems is high peak-to-average-power ratio (PAPR) of its transmitted signal, many PAPR reduction techniques and combined schemes with individual techniques have recently been developed. Among various techniques, the clipping technique has been widely used as a practical scheme owing to its low computational complexity and simplicity in implementation, while the selected mapping (SLM) technique is known to provide good PAPR reduction performance without signal distortion. Generally, the combined scheme of two PAPR reduction techniques, which are the clipping and the SLM, is expected to provide the enhanced performance of PAPR reduction, because the clipping noise of combined scheme would be less than that of single clipping technique, when the SLM technique is employed before clipping. However, the performance of clipping scheme with SLM technique has not been evaluated for practical systems over fading channels. In this paper, the performance of the clipping scheme with the SLM technique is theoretically analyzed and compared with simulation results over fading channels. The performance of combined scheme is analyzed with various clipping ratios, phase sets for SLM, and modulation schemes over flat and frequency selective fading channels. In addition, the effects of the clipping at the receiver and the oversampling on the BER performance are discussed. Based on the results of analysis, therefore, one can design the effective clipping scheme with the SLM technique for the PAPR reduction of OFDM-based systems.

Combination of selected mapping and statistical redistribution method for reducing peak to average power ratio in OFDM systems

Orthogonal frequency-division multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. One major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the transmitter’s output signal. The selected mapping (SLM) approach provides good performance for PAPR reduction, but it requires a bank of inverse fast Fourier transforms (IFFTs) to generate a set of candidate transmission signals, and this requirement usually results in high computational complexity. In selected mapping (SLM) method a whole set of candidate signals is generated representing the same information, and then the most favourable signal as regards to PAPR is chosen and transmitted. SLM scheme is one of the initial probabilistic approaches for reducing the PAPR problem, with a goal of making occurrence of the peaks less frequent, not to eliminate the peaks. The scheme can handle any number of subcarriers and drawback associated with the scheme is the overhead of side information that needs to be transmitted to the receiver. This paper studies the problem of peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) system. It introduces a new PAPR reduction method that performs signal processing in the OFDM time domain together with the SLM method. The simple non-linear amplitude pre-distortion process of the proposed method changes the statistical characteristics of the OFDM symbol from Rayleigh distribution into Gaussian like distribution. This change in statistical distribution is accompanied by changes of the peak and average power values and consequently reduces in the PAPR value. For the QPSK OFDM system with 128 sub-carriers, 3dB reduction in PAPR value is achieved. The proposed method shows that SLM with square rooting have higher PAPR reduction compare to the original SLM method. The approach is very flexible and can work with arbitrary number of sub-carries without restriction on the type of modulation applied on them.

Partial Transmit Sequences for Peak-to-Average Power Ratio Reduction of OFDM Signals With the Cross-Entropy Method

This letter considers the use of the partial transmit sequence (PTS) technique to reduce the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. The conventional PTS technique can provide good PAPR reduction performance for OFDM signals; however, it requires an exhaustive search over all combinations of allowed phase factors, resulting in high complexity. In order to reduce the complexity while still improving the PAPR statistics of an OFDM signal, a new method using the cross-entropy (CE) method is proposed to reduce both the PAPR and the computational load. In the proposed CE method, we first define a score or fitness function based on the corresponding PAPR reduction performance. The score function is then translated into a stochastic approximation problem which can be solved effectively. The simulation results show that the performance of the proposed CE method provides almost the same PAPR reduction as that of the conventional exhaustive search algorithm while maintaining low complexity.

Sub-optimum PTS for PAPR reduction of OFDM signals

As an attractive technique for peak-to-average power ratio (PAPR) reduction, partial transmit sequences (PTS) provides good PAPR reduction performance for orthogonal frequency division multiplexing (OFDM) signals. However, optimum PTS (OPTS) requires an exhaustive search over all combinations of allowed phase factors, resulting in the high complexity. Proposed is a sub-optimum partial transmit sequences (sub-OPTS) for PAPR reduction of OFDM signals. In sub-OPTS, both the alternate optimisation and the linear property of inverse discrete Fourier transform are employed. Simulation results show that sub-OPTS can reduce the computational complexity dramatically and achieve almost the same PAPR reduction performance compared to OPTS.

A hybrid PAPR reduction scheme for coded OFDM

We consider schemes for reducing the peak-to-average power ratio (PAPR) in coded orthogonal frequency-division multiplexing (OFDM) systems. We develop a new PAPR reduction technique using the label-inserted encoder of a random-like code and the soft amplitude limiter (SAL). Using this hybrid scheme provides 5.5 dB PAPR reduction in an OFDM system with 128 subcarriers, 4-bit selection and 3 dB clipping. Besides the significant PAPR reduction, the scheme also enjoys other advantages such as small overhead, low complexity, no side information transmission, and little performance loss. Among various random-like codes, the irregular repeat accumulate (IRA) code is the best choice for its simple encoder and capacity achieving performance. The scheme can be directly applied to multiple-input multiple-output (MIMO) OFDM systems. The capacity of the clipped MIMO-OFDM systems is analyzed based on a Gaussian approximation of the clipping noise. We consider an iterative receiver with soft MAP MIMO-OFDM detector. For both single antenna and multiple antenna systems, the encoder part is independent in the hybrid scheme, thus no additional constraint is applied to the IRA code optimization. The IRA codes are designed for the ergodic MIMO-OFDM systems with different PAPR reduction settings, more specifically different clipping ratios, based on the extrinsic information transfer (EXIT) charts. Simulation results show that the hybrid scheme with 3 dB clipping can achieve as good PAPR reduction performance as the simple clipping with 0 dB ratio but incurs much less performance loss at the receiver