Proposed Partial Transmit Sequence Scheme Research Articles

Designing a Novel PTS Method to Reduce Peak to Average Power Ratio in OFDM

Most of the wireless standards used these days, heavily rely on Orthogonal Frequency Division Multiplexing (OFDM). Peak to Average Power Ratio (PAPR) is one of the known key acknowledged confines of OFDM. Reduced PAPR at OFDM transmitter helps power amplifier to operate in stable mode and reduction in complexity of digital to analog converter (DAC). Several PAPR reduction techniques have been evolved from different principles such as signal scrambling techniques, such as Partial Transmit Sequence (PTS), signal distortion techniques such as Clipping, etc. Reducing PAPR degrades bit error rate (BER) or computational complexity. PTS is one of the best methods of PAPR reduction. There is large scope of betterment of PTS to get a best PAPR reduction technique. In this paper we have concentrated on PTS scheme by exploring PTS and its variants evolved over a period of time. We proposed a novel PTS with best performance balancing PAPR and BER performance. Design and development of scheme is done using a graphical programming environment LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench) and real time environment validation is done with software defined radio – NIUSRP2922, which is National Instruments Universal Software Radio Peripheral. The paper has three sections in first section, Introduction, the OFDM fundamentals and PAPR are defined in design perspective, in second section conventional and proposed PTS schemes have been explained. The third section consists of result and conclusion.

New PTS Schemes With Adaptive Selection Methods of Dominant Time-Domain Samples in OFDM Systems

In orthogonal frequency division multiplexing (OFDM) systems, high peak-to-average power ratio (PAPR) of OFDM signals is one of the most important problems. As a solution to the PAPR problem in OFDM systems, the partial transmit sequence (PTS) is a fairly suitable scheme due to its PAPR reduction performance and distortionless characteristic. However, high computational complexity is a serious problem in the PTS scheme. In this paper, in an effort to reduce its computational complexity, new PTS schemes are proposed using dominant time-domain samples of OFDM signals. Although the proposed PTS schemes use dominant time-domain samples in a manner similar to several existing low-complexity PTS schemes, we propose more efficient selection methods for dominant time-domain samples. The proposed PTS schemes lower the computational complexity compared to the conventional PTS schemes while achieving the optimal PAPR reduction performance.

New PTS Schemes for PAPR Reduction of OFDM Signals Without Side Information

In this paper, two partial transmit sequence (PTS) schemes without side information (SI) are proposed for reducing peak-to-average power ratio of orthogonal frequency division multiplexing signals. The proposed schemes do not transmit SI identifying a rotating vector because identifiable phase offset is applied to the elements of each rotating vector. To extract SI from the received signal and recover the data sequence, the maximum likelihood (ML) detector is used. This ML detector exploits the Euclidean distance between the given signal constellation and the signal constellation rotated by the phase offset. By doing pairwise error probability (PEP) analysis, it is investigated how to choose good phase offsets for embedding SI. Also, the performance degradation caused by SI detection failure is analyzed based on PEP. Finally, through numerical analysis, it is shown that the BER performance of the proposed PTS schemes is not degraded compared with the conventional PTS with perfect SI.

Low-complexity PTS PAPR reduction scheme for UFMC systems

In this study, a low-computational-complexity partial transmit sequence (PTS) is proposed for reducing peak-to-average power ratios (PAPRs) of universal filtered multi-carriers (UFMCs). First, we analyze the differences in PAPR between a UFMC system and an orthogonal frequency division multiplexing system. Second, we characterize the threshold of the minimum peak power of the UFMC symbol and delete the candidate signal samples with power values below the threshold. This allows for a reduction in the number of time-domain samples that are multiplied by the corresponding phase-rotating vectors; in addition, it can be used for estimating the PAPR. Third, considering the relationship between the phase-weighting sequences, the computational complexity of the candidate signals is simplified. Numerical results show that the proposed PTS scheme achieves nearly the same PAPR reduction as that achieved by the conventional PTS scheme; meanwhile, it has considerably low computational complexity when the probability, $$\beta $$ , of the maximum peak power being more than the possible minimum peak power is greater than or equal to 0.5.

Low-Complexity PTS Schemes Using Dominant Time-Domain Samples in OFDM Systems

Partial transmit sequence (PTS) is a probabilistic peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) signals, but it requires an exhaustive search for the one with the minimum PAPR over all alternative OFDM signal vectors. In order to reduce such computational complexity, it was proposed that the PAPR value of each alternative OFDM signal vector is approximately estimated by using dominant time-domain samples selected based on a simple metric. In this paper, two new effective metrics for selecting dominant time-domain samples are proposed for low-complexity PTS scheme. For further lowering the computational complexity, two low-complexity PTS schemes are proposed by sorting the dominant time-domain samples in decreasing order of their metric values. Simulation results confirm that compared with the conventional PTS scheme, the proposed PTS schemes show identical PAPR reduction performance with substantially reduced computational complexity.

PAPR Reduction of Multicarrier Faster-Than-Nyquist Signals With Partial Transmit Sequence

Multicarrier faster-than-Nyquist (MFTN) signaling is a spectral efficient transmission scheme for future communication systems. Similar as general multicarrier signals, the high peak-to-average power ratio (PAPR) is also one of the main drawbacks of MFTN signals. Unfortunately, the PAPR problem in MFTN signaling system has rarely been considered in the literatures. In this paper, we investigate the PAPR reduction for MFTN signals. First, we derive an inverse fast Fourier transform (IFFT)-based implementation of the MFTN transmitter. Based on which, a novel partial transmit sequence (PTS) scheme is proposed for the PAPR reduction of MFTN signals. The proposed PTS scheme relies on a two-stage optimization of the phase weighting factors for the parallel IFFT blocks as well as the phase weighting factors for the information symbols before the summation operation. It is shown that the proposed scheme substantially outperforms the direct employment of conventional Nyquist multicarrier transmission systems-based PTS scheme and also robust to the overlap-add operation introduced by pulse shaping.

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.

Implementation of a Low Complexity Peak-to-Average Power Ratio Reduction Scheme on Field Programmable Gate Array

Orthogonal frequency division multiplexing systems suffer from one main drawback which is a high peak-to-average power ratio (PAPR) that leads to power efficiency degradation and when feed to a power amplifier operating in the nonlinear region yields adjacent channel interference and inferior bit error rate performance. There are many methods to overcome this drawback, one example of which is partial transmit sequence (PTS). Here implementation of a proposed PTS on field programmable gate array platform to show the feasibility of the PAPR reduction scheme is carried out. It has been shown that the proposed PTS scheme is significantly simpler as compared to the conventional methods and integration of this scheme with digital pre-distortion technique improves the system efficiency, suppressed out-of-band distortion and hence, prolong battery life. The simulations have been carried out with QPSK modulation and inverse fast Fourier transform with 512 subcarriers. The implementation results show in average 21 % reduction in hardware resource and almost 18 % conservation in total power consumption by applying the new PTS scheme while its PAPR performance remains comparable to the conventional PTS method.

Peak‐to‐average power ratio reduction in Alamouti multi‐input–multi‐output orthogonal frequency division multiplexing systems without side information using phase offset based‐partial transmit sequence scheme

In this study, a novel phase offset-based partial transmit sequence (PTS) scheme is proposed to reduce the peak-to-average power ratio (PAPR) in Alamouti coded multi-input-multi-output orthogonal frequency division multiplexing systems, and its key idea is that different phase rotation sequences are multiplied by their corresponding phase offsets at the transmitter. Moreover, a minimum Euclidean distance decoder is proposed to recover the phase rotation sequences at the receiver. The theoretical analysis and simulation results show that the proposed PTS scheme could offer good performances of both the bit error rate and the PAPR reduction without transmitting the side information, resulting in the increase of the data rate.

AN EFFICIENT METHOD FOR PAPR REDUCTION IN OFDM SYSTEMS WITH REDUCED COMPLEXITY

Orthogonal Frequency Division Multiplexing (OFDM), widely used in digital wireless communication, has a major drawback of high Peak to Average Power Ratio (PAPR). A reduced complexity partial transmit sequence (PTS) scheme has been proposed to solve high peak to average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) system. In the proposed PTS scheme, a function is generated by summing the power of time domain samples at time ‘n’ in each sub blocks, known as “Hn”.Only those samples, having Hn greater than or equal to a preset threshold value (αT) are used for peak power calculation during the process of selecting a candidate signal with the lowest PAPR for transmission. As compared to conventional PTS scheme, the proposed scheme achieves almost the same PAPR reduction performance with much lower 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.

Efficient PAPR reduction scheme for satellite MC-CDMA systems

Multicarrier code-division multiple access (MC-CDMA) is one of the most promising techniques to provide future broadband mobile satellite services. However, the high peak-to-average power ratio (PAPR) in MC-CDMA causes significant signal distortion, and this problem is even more serious in satellite systems. An efficient partial transmit sequence (PTS) scheme is proposed to reduce PAPR in a satellite MC-CDMA system. A new phase factor optimisation algorithm is used to reduce the complexity of the conventional PTS scheme. After analysing various performance characteristics of MC-CDMA in the presence of nonlinear distortion from a high-power amplifier, extensive performance simulation results are provided of various PTS schemes for satellite MC-CDMA systems. The simulation results reveal that the proposed PTS scheme reduces the PAPR by about 0.3 dB, coupled with a 25% reduced complexity, compared with the conventional scheme.