• ETRI Journal
• /
• v.40 no.6
• /
• pp.699-713
• /
• 2018

Orthogonal frequency division multiplexing (OFDM) has been the overwhelmingly prevalent choice for high-data-rate systems due to its superior advantages compared with other modulation techniques. In contrast, a high peak-to-average-power ratio (PAPR) is considered the fundamental obstacle in OFDM systems since it drives the system to suffer from in-band distortion and out-of-band radiation. The partial transmit sequence (PTS) technique is viewed as one of several strategies that have been suggested to diminish the high PAPR trend. The PTS relies upon dividing an input data sequence into a number of subblocks. Hence, three common types of the subblock segmentation methods have been adopted - interleaving (IL-PTS), adjacent (Ad-PTS), and pseudorandom (PR-PTS). In this study, a new type of subblock division scheme is proposed to improve the PAPR reduction capacity with a low computational complexity. The results indicate that the proposed scheme can enhance the PAPR reduction performance better than the IL-PTS and Ad-PTS schemes. Additionally, the computational complexity of the proposed scheme is lower than that of the PR-PTS and Ad-PTS schemes.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10c
• /
• pp.319-321
• /
• 2001

ADSL에서 사용되고 있는 DMT(Discrete Multitone)는 Multicarrier Modulation 기법으로 선로의 특성을 고려하여 고속의 bit-rate를 얻을 수 있다. 그러나 이러한 Multicarrier 신호의 문제점은 바로 높은 PAR(Peak-to-Average Ratio)로, 이 값을 줄이기 위해 여러 가지 기법이 사용되고 있다. 본 논문에서는 현재 PAR을 줄이기 위해 사용되고 있는 여러 기법에 대해서 설명하고, 그 기법들 중에서 PTS(Partial Transmit Sequence)를 개선한 새로운 알고리즘을 제시하여 성능평가를 통해 낮은 복잡도의 계산으로 PTS와 유사한 성능을 보임을 살펴본다.

• ETRI Journal
• /
• v.39 no.6
• /
• pp.782-793
• /
• 2017

This paper 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 signal in wireless communication systems. Search complexity is very high in the traditional PTS scheme because it involves an extensive random search over all combinations of allowed phase vectors, and it increases exponentially with the number of phase vectors. In this paper, a suboptimal metaheuristic algorithm for phase optimization based on an improved harmony search (IHS) is applied to explore the optimal combination of phase vectors that provides improved performance compared with existing evolutionary algorithms such as the harmony search algorithm and firefly algorithm. IHS enhances the accuracy and convergence rate of the conventional algorithms with very few parameters to adjust. Simulation results show that an improved harmony search-based PTS algorithm can achieve a significant reduction in PAPR using a simple network structure compared with conventional algorithms.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.10
• /
• pp.1-9
• /
• 1999

In this paper, a subblock partition scheme for reduction of computational complexity in partial transmit sequence which reduces the peak-to-average power ratio in orthogonal frequency division multiplexing (OFDM) is proposed. In this scheme, complex signals are assigned into partial subbands randomly and signals in a partial subband are duplicated and concatenated repetitively to make a subblock. By modulation of active subbands which have almost interleaved pattern, computational complexity can be reduced. As results of computer simulation, the proposed shows almost same peak to average power ratio reduction performance as compared to the conventional one. However, computational complexity required to transmit a partial transmit sequence OFDM symbol has been reduced extensively.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.6
• /
• pp.2201-2216
• /
• 2015

Peak to average power ratio (PAPR) is one of the main imperfections in the broadband communication systems with multiple carriers. In this paper, a new crest factor reduction (CFR) scheme based on interleaved phase sequence called Dummy Sequence Insertion Enhanced Partial Transmit Sequence (DSI-EPTS) is proposed which effectively reduces the PAPR while at the same time keeps the total complexity low. Moreover, the prototype of the proposed scheme in field programmable gate array (FPGA) is demonstrated. In DSI-EPTS scheme, a new matrix of phase sequence is defined which leads to a significant reduction in hardware complexity due to its less searching operation to extract the optimum phase sequence. The obtained results show comparable performance with slight difference due to the FPGA constraints. The results show 5 dB reduction in PAPR by applying the DSI-EPTS scheme with low complexity and low power consumption.

• Proceedings of the KIEE Conference
• /
• 2007.11c
• /
• pp.70-73
• /
• 2007

Many methods have been developed to overcome the PAPR(peak-to-average power ratio) problem. Selective mapping(SLM) partial transmit sequence(PTS), subblock phase weighting(SPW) and gradient descent(GD) are used widely to reduce the PAPR. In this paper, we present a effective PAPR reduction method, decrease the calculation through Radix-2 DIF IFFT procedure and GD method. and can transmit selecting data sequence that satisfy threshold value as one part of proposed method, in case satisfy fixed threshold value, or transmit selecting data sequence with the lower papr operating remained part for performance improvement.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.9C
• /
• pp.914-920
• /
• 2006

In this paper, we introduce a new partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. In the proposed scheme, $2^n$-point inverse fast Fourier transform (IFFT) is divided into two parts. An input symbol sequence is partially transformed using the first l stages of IFFT into an intermediate signal sequence and the intermediate signal sequence is partitioned into a number of intermediate signal subsequences. Then, the remaining n - l stages of IFFT are applied to each of the intermediate signal subsequences and the resulting signal subsequences are summed after being multiplied by each member of a set of W rotating vectors to yield W distinct OFDM signal sequences. The one with the lowest peak to average power ratio (PAPR) among these OFDM signal sequences is selected for transmission. The new PTS OFDM scheme reduces the computational complexity while it shows almost the same performance of PAPR reduction as that of the conventional PTS OFDM scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.7
• /
• pp.685-691
• /
• 2004

In this paper, we propose the hybrid methods of SLM(selected mapping) and predistortion, and PTS(partial transmit sequence) and predistortion to reduce PAPR(peak to average power ratio) and to decrease the nonlinear distortion of the nonlinear HPA(high power amplifier) in the multi-code CDMA(code division multiple access) system. The phase rotation factors are transmitted as side information in PTS and SLM methods play an important role in the BER performance. So, we present the theoretical BER equation when the errors of side information are considered in the multi-code CDMA communication system. Simulation results show that PAPR is reduced and nonlinear distortion is compensated by hybrid methods. Therefore BER performance is enhanced.

• ETRI Journal
• /
• v.43 no.2
• /
• pp.209-220
• /
• 2021

The filtered orthogonal frequency division multiplexing (F-OFDM) system has been recommended as a waveform candidate for fifth-generation (5G) communications. The suppression of out-of-band emission (OOBE) and asynchronous transmission are the distinctive features of the filtering-based waveform frameworks. Meanwhile, the high peak-to-average power ratio (PAPR) is still a challenge for the new waveform candidates. Partial transmit sequence (PTS) is an effective technique for mitigating the trend of high PAPR in multicarrier systems. In this study, the PTS technique is employed to reduce the high PAPR value of an F-OFDM system. Then, this system is compared with the OFDM system. In addition, the other related parameters such as frequency localization, bit error rate (BER), and computational complexity are evaluated and analyzed for both systems with and without PTS. The simulation results indicate that the F-OFDM based on PTS achieves higher levels of PAPR, BER, and OOBE performances compared with OFDM. Moreover, the BER performance of F-OFDM is uninfluenced by the use of the PTS technique.

• The Journal of the Korea Contents Association
• /
• v.6 no.1
• /
• pp.1-7
• /
• 2006

This paper proposes a new method that reduces the complexity of the combined system, which consists of the selective mapping(SLM) and the partial transmit sequence(PTS) in the Orthogonal Frequency Division Multiplexing(OFDM). In order to reduce the Peak-to-Average Power Ratio(PAPR), many techniques have been developed such as SLM and PTS. and their combined systems. However the method that simply combines PTS and SLM to improve the effectiveness of a system increases the complexity of calculation. The scheme employed in this research suggests a system that combines PTS and SLM reducing the complexity via the N($N=2^n$)-point inverse fast Fourier transforms(IFFT), which uses the decimation in time domain not only to improve PAPR but also to reduce the amount of calculation. The proposed method reduces the complexity by multiplying a phase sequence and a subblock index to the data sequences in the middle of IFFT, which yields an optimal sequence with minimal PAPR. The superiority of the proposed method is demonstrated by simulation results and analysis.