• Title/Summary/Keyword: peak-to-average power ratio

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A Mapped Mc-OFDM Cooperative Communications System to Reduce PAPR and Improve Data Reliability (데이터 신뢰성 향상과 PAPR 감소를 위한 매핑된 Mc-OFDM 협력 통신 시스템)

  • Hwang, Yun-Kyeong;Kong, Hyung-Yun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.11
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    • pp.1254-1261
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    • 2007
  • Mc-OFDM(Multi code-Orthogonal Frequency Division Multiplexing) modulation has been developed for high-speed data transmission over wireless channels. However, this system suffers critical problem from relatively high PAPR(Peak to Average Power Ratio). To reduce PAPR, we suggest a new technique, called Mapping using (N+1)PSK and demonstrate the performance of mapped Mc-OFDM system. On the other side, in OFDM system, each sub-carrier experiences different fading, thus some sub-carriers may be completely lost because of deep fade. To solve a above mention problem, we propose cooperative communications that improve the reliability of sub-carriers through spatial diversity.

PAPR Reduction Improvement for WHT-based OFDM System using Data Grouping Technique (왈시-하다마다 변환과 DGT 기술을 이용한 OFDM 시스템의 PAPR 감소 및 BER성능향상을 위한 연구)

  • Kong Hyung-Yun;Khuong Ho Van;Nam Doo-Hee
    • The KIPS Transactions:PartC
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    • v.12C no.4 s.100
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    • pp.511-518
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    • 2005
  • The conventional OFDM (Orthogonal Frequency Division Multiplexing) modulation can be combined with WHT (Walsh-Hadamard Transform) to reduce PAPR (Peak-to-Average Power Ratio) and improve BER (Bit Error Rate) performance. However, this WHT-based OFDM system still suffers a relatively high PAPR. Therefore, we suggest a new technique, called DGT (Data Grouping Technique) and design an OFDM system employing it and WHT to further decrease PAPR without the BER performance degradation. h salient property of DGT is the independence of the side information which is inherently a principal drawback of the well-known PAPR reduction techniques for OFDM system as well as WHT-based OFDM. The simulation programs have been also performed to verify the validity of the proposed system.

Performance Analysis of Combining Method for PAR Reduction in OFDM (OFDM에서 PAR을 제거하기 위한 혼합방법의 성능 해석)

  • 김병주;변건식
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.11a
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    • pp.163-166
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    • 2002
  • OFDM should be used for the fourth generation communication for high speed communication. Because of high spectral efficiency and high tolerance to fading channel, OFDM is applied to many high speed wire and wirless communication such as DAB(Digital Audio Broudcast), DVB(Digital Video Broadcast), IMT 2000 etc. Inter-modulation, however, is derived from PAR(Peak to Average Power Ratio) of OFDM signals. The paper describes PTS(Partial Transmit Sequence) and SLM(Select Mapping) of an existing methods which can reduce PAR. And then the document introduces the new method that is called "Combine PAR method". The method proposed in this paper is to combine PTS and SLM. As a result of the simulation, Combine PAR method is better than the existing methods.g methods.

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위성 WiBro 신호전송 및 보상기법

  • Lee, Byeong-Seop
    • TTA Journal
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    • s.109
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    • pp.56-63
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    • 2007
  • 위성을 이용하여 초고속 이동체를 대상으로 한 WiBro 서비스를 제공하는데 있어서 OFDM(Orthogonal Frequency Division Multiplexing) 신호의 특징인 과대한PAR(Peak To Average Power Ratio)로 인한 위성중계기에서의 비선형 간섭신호 분석과 이를 극복할 수 있는 변조방식에 대하여 논하고 아울러 시속 300Km가 넘는 초고속 이동체에서 OFDM 신호를 송, 수신하는 경우 Doppler 주파수 편이에 따른 WiBro 수신성능 열화를 분석하고 이를 효과적으로 극복할 수 있는 새로운 방법을 제안한다.

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An Orthogonal Phase-Superimposed Peak-to-Average Power Ratio Reduction Technique

  • Han, Tae-Young;Kim, Nam;Choi, Jung-Hun;Lee, Jae-Hwan
    • Journal of electromagnetic engineering and science
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    • v.7 no.4
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    • pp.169-174
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    • 2007
  • This paper presents a method of superimposing the rotation phases over the pilot and data symbols in order to reduce the peak-to-average power ratio(PAPR) in orthogonal frequency division multiplexing(OFDM). The phases of the rotation vector are added to those of the pilot symbols and those of the data symbols by interlaying them between any two pilot symbols. The receiver restores the data symbols by utilizing the channel estimation of the pilot symbols. Therefore, the bandwidth efficiency is improved by not using the subcarriers that are assigned for the reduction of the PAPR. Also, the enormous increase of the bit error rate which would be caused by incorrectly receiving the side information, i.e. the phases of the rotation vector, is prevented. The simulation results of the bit error rate performance for the BPSK are given using the COST-207 channel model.

Performance Evaluation of Multi-Phased MC-CD74A System for transmitting the High Rate Data (고속데이터 전송을 위한 Multi-Phased MC-CDMA 시스템의 제안 및 성능 분석)

  • 안철용;안치훈;김동구;류승문
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.12B
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    • pp.1637-1647
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    • 2001
  • Multi-Code CDMA (MC-CDMA) can not only be integrated easily with a conventional system, but also achieve good spectral efficiency and high processing gain. However, it suffers from high value of peak-to-average power ratio (PAPR). In this paper, we propose the Multi-Phase CDMA (MP-CDMA) system that can provide variable rate service and is not susceptible to the non-linear characteristics of amplifier. The clipping is introduced between at the output of multi-code modulator and at the input of MPSK modulator in order to improve the performance of MPSK chip demodulator and reduce the system complexity, The system performances are compared for the different Number of codes and different clipping levels, respectively. The optimum clipping level is also evaluated for the different number of codes in both, AWGN and frequency flat fading channel.

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Adaptive P-SLM Method with New Phase Sequence for PAPR Reduction of MIMO-OFDM Systems (MIMO-OFDM 시스템의 PAPR 감소를 위한 새로운 위상시퀀스의 적응형 P-SLM기법)

  • Yoo, Eun-Ji;Byun, Youn-Shik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.3C
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    • pp.149-156
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    • 2011
  • MIMO-OFDM(Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) has been spotlighted as a solution of high-quality service for next generation's wireless communications. However, like OFDM, one of main problems of MIMO-OFDM is the high PAPR(Peak-to-Average Power Ratio). In this paper, an adaptive P-SLM(Partitioned-SeLetive Mapping) based on new phase sequence is proposed to reduce PAPR. The proposed method has better performance and lower complexity than conventional method due to the use of periodic multiplication and adaptability by fixed critical PAPR value. Simulation results show that the proposed method has better performance and lower complexity than conventional method.

Degradation of OFDM Signal Performance by Chromatic Dispersion in a Several 10 Gbit/s Mobile Front-haul Link (수 10 Gbit/s 모바일 프론트홀 링크에서 색분산에 의한 OFDM 신호 전송성능 열화 분석)

  • Won, Yong-Yuk;Seo, Dongsun
    • Journal of IKEEE
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    • v.20 no.1
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    • pp.26-30
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    • 2016
  • In this paper, an inter-orthogonal frequency division multiplexing (OFDM) sub-carrier distortion due to fiber chromatic dispersion is investigated. The fiber chromatic dispersion induces phase difference among OFDM sub-carriers, resulting in non-symmetric peak to average power ratio (PAPR) inducing inter-OFDM distortion. Experiments to confirm the fiber dispersion are performed in a direct-detection optical front-haul link. Quadrature phase shift keying (QPSK) encoded OFDM symbols at 25 Gbit/s are transmitted over 100 km fiber and the resulting error vector magnitude (EVM) of 40 % is observed.

A Parallel Combinatory OFDM System with Weighted Phase Subcarriers

  • Zheng, Hui;Shrestha, Robin;Hwang, Jae-Ho;Kim, Jae-Mong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.1
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    • pp.322-340
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    • 2012
  • Orthogonal Frequency Division Multiplexing (OFDM) is usually regarded as a spectral efficient multicarrier modulation technique, yet it suffers from a high peak-to-average power ratio (PAPR) problem. Among all the existing PAPR reduction techniques in OFDM systems, side information based PAPR reduction techniques such as partial transmit sequence (PTS) and selective mapping (SLM) schemes, have attracted the most attention. However, the transmission of side information results in somewhat spectral loss and this does not significantly improve the bit error rate (BER) performance. Parallel combinatory (PC) OFDM yields higher spectral efficiency (SE) and better BER performance on Gaussian channels,while is a little but not obvious PAPR improvement over the ordinary OFDM system. This investigation aimed to design a 'perfect' OFDM system. We introduce the side information to rotate the subcarrier phases of our novel PC-OFDM system structure, and call this new system the SIPC(Side information based Parallel Combinatory)-OFDM system. The proposed system achieves better PAPR and SE performance. In addition, considering the tradeoff of system parameters, the proposed system also has the properties of a higher BER.

A Study on PAPR Reduction and Compensation for In-Band Distortion in OFDM Systems (OFDM 시스템에서 PAPR의 감소와 대역 내 왜곡 보정에 관한 연구)

  • Kim, Wan-Tae;Yoo, Sun-Yong;Cho, Sung-Jun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.5
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    • pp.912-920
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    • 2008
  • OFDM (Orthogonal Frequency Division Multiplexing) system is robust to frequency selective fading and narrowband interference in high-speed data communications. However, an OFDM signal consists of a number of independently modulated subcarriers, which can give a large PAPR (Peak-to-Average Power Ratio) when added up coherently. In this paper, we apply clipping and filtering to solve the PAPR problem and compensate the inband compensation using calculated EVM (Error Vector Magnitude). The proposed method can reduce the PAPR and inband distortion. From the results, we analyze the PAPR reducing efficiency and EVM, BER performance of proposed algorithm in the wireless communication system.