• Title/Summary/Keyword: Orthogonal modulation

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Performance of OFDM M-ary QAM System in the presence of Carrier Frequency Offset (반송파 주파수 옵셋에 따른 OFDM M-ary QAM 시스템의 성능 분석)

  • 계선형;유형석;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1024-1031
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    • 1999
  • In order to transmit high-speed wide band signals efficiently in multipath fading environments, M-ary QAM signalling combined with OFDM transmission technique is applied. In this paper, the effect of synchronization error caused by carrier frequency offset and SER(Symbol Error Rate) performance of OFDM-16QAM and OFDM-64QAM are theoretically analyzed. Our result shows that as the number of sub-carrier in OFDM system increases the frequency-offset caused inter-channel interference(ICI) increases significantly, and that an error floor occurs even at high SNR of OFDM system. For OFDM-64QAM, the error floor occurs at SER=1$\times$10-7 when a normalized frequency-offset is 0.001, in which the SNR degradation is much greater than that of OFDM-16QAM. From this study the maximum allowable frequency-offset of OFDM-16QAM and OFDM-64QAM systems can be determined to meet the specific SER requirement.

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Design and Performance Evaluation of M×M MIMO Transmission in ESPAR Antenna (ESPAR 안테나에서 M×M MIMO 송신방식의 설계와 성능 평가)

  • Bok, Junyeong;Lee, Seung Hwan;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.12
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    • pp.1061-1068
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    • 2013
  • In this paper, we propose a $M{\times}M$ beam-space multiple input multiple output (BS-MIMO) system using electronically steerable parasitic array radiator (ESPAR) antenna. Conventional MIMO method required multiple RF chains because it map the transmission signals onto multiple antennas. So, conventional MIMO system has high cost for design and high energy consumption at RF circuit. Also, It is difficult to use MIMO system in battery based mobile terminals with limited physical area. In order to solve these problems, BS-MIMO technique which map the data signal onto bases in beam space domain was proposed using ESPAR antenna with single RF chain. This paper, we design and analyze the performance of extended $M{\times}M$ BS-MIMO technique. Simulation results show that the proposed BS-MIMO system has similar BER performance compare to conventional MIMO scheme. Therefore, BS-MIMO system with single RF chain will has a low RF power consumption and low cost for RF hardware design as compared with conventional MIMO technique with multiple RF chains.

Performance Analysis on DMB System with PAPR Reduction Techniques (PAPR 저감기법을 적용한 DMB 시스템의 성능분석)

  • 정영호;함영권;김환우
    • Journal of Broadcast Engineering
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    • v.8 no.3
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    • pp.238-249
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    • 2003
  • Eureka 147 DAB system based on the orthogonal frequency division multiplexing (OFDM) was adopted as the transmission scheme for terrestrial digital multimedia broadcasting (DMB) system in Korea. The OFDM has several advantages comparing to the single carrier modulation. However, its high Peak-to-average power ratio (PAPR) increases the complexity of the D/A and A/D converters and reduces the efficiency of the high power amplifier To reduce the high PAPR of OFDM, various techniques such as clipping, peak windowing, companding, selected mapping (SLM), Partial transmit sequences (PTS), etc. have been proposed. In this paper, we propose modified configurations of SLM and PTS for effective implementation and evaluate the performance on the PAPR reduction of DMB system. The simulation results show that the modified SLM (MSLM) has merits in reducing the amount of computation and hardware complexity due to the reduction of the number of vector $P^{(U)}$, while satisfying the same performance and maintaining the same required bits (RB) for side information. With the same amount of computation and the same RB, the modified PTS (MPTS) is also shown to be better than PTS in the performance of PAPR reduction.

Design, fabrication, and evaluation of RF module in compliance with the IEEE 802.11a standard for 5GHz-band Wireless-LAN applications (IEEE 802.11a 규격을 만족하는 5GHz 대역 무선 랜용 RF 모듈의 설계, 제작과 성능 평가)

  • 권도훈;김영일;이성수;박현철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.3C
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    • pp.248-255
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    • 2002
  • An RF module in compliance with the IEEE 802.11a standard has been designed and its performance has been measured. Conventional heterodyne architecture with 580MHz intermediate frequency has been realized. Measurement results show that the receiver has a low Noise Figure of 5dB, the maximum gain of 70dB, and dynamic range as wide as 61dB. Also, the SAW filter used for channel selection in the IF section allowed minimum inter-channel interference. in addition to satisfying the RF output power requirement, the transmitter features its output P1dB as high as 34dBm so that the high peak-to-average ratio of the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme can be handled with minimum nonlinear distortion. The output P1dB of 34dBm of the transmitter corresponds to back-off powers of 18dB and 11dB with respect to the output power for the low and the middle frequency bands, respectively.

On Design and Performance Analysis of Asymmetric 2PAM: 5G Network NOMA Perspective (비대칭 2PAM의 설계와 성능 분석: 5G 네트워크의 비직교 다중 접속 관점에서)

  • Chung, Kyuhyuk
    • Journal of Convergence for Information Technology
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    • v.10 no.10
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    • pp.24-31
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    • 2020
  • In non-orthogonal multiple access (NOMA), the degraded performance of the weaker channel gain user is a problem. In this paper, we propose the asymmetric binary pulse amplitude modulation (2PAM), to improve the bit-error rate (BER) performance of the weaker channel user in NOMA with the tolerable BER loss of the stronger channel user. First, we design the asymmetric 2PAM, calculate the total allocated power, and derive the closed-form expression for the BER of the proposed scheme. Then it is shown that the BER of the weaker channel user improves, with the small BER loss of the stronger channel user. The superiority of the proposed scheme is also validated by demonstating that the signal-to-noise ratio (SNR) gain of the weaker channel user is about 10 dB, with the SNR loss of 3 dB of the stronger channel user. In result, the asymmetric 2PAM could be considered in NOMA of 5G systems. As a direction of the future research, it would be meaningful to analyze the achievable data rate for the propsed scheme.

The Comparison of Filter Performance in UFMC systems (UFMC 시스템에서 필터성능 비교)

  • Lee, Kyuseop;Choi, Ginkyu
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.6
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    • pp.89-95
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    • 2017
  • UFMC is known as a candidate for the 5G wireless communication system because it is robust against ICI and better performs in asynchronous situation than OFDM. In the UFMC system, the filtering is performed for each subband so the performance of the filter is very important. The Dolph-Chebyshev filter has been used in conventional UFMC system because of its small out-of-band radiation. However it has distortion in the sub-band and skirt characteristics is not good enough. Therefore, it is necessary to study a new type of UFMC filter which reduces the distortion in the subband and has sharp skirt characteristics. In this paper we analyze the effect of filter frequency response in UFMC system and suggest the wavelet based type of filter that substitutes the Dolph-ChebyShev filter used in the conventional UFMC system. The simulation results show that wavelet filter has better BER performance in multipath fading channels than conventional filters.

Performance Analysis of OFDM M-ary QAM System with One Tap Equalizer in Rummler Fading Channel (룸머 페이딩 환경 하에서 단일 탭 등화기를 사용한 OFDM M-ary QAM 시스템의 성능 분석)

  • 심재옥;김언곤
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.2
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    • pp.175-180
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    • 2002
  • In this paper, the system performace with the convolution rode using a Viterbi decoding and the one tap LMS(Least Meam Square) equalizer applied to the OFDM(Orthogonal Frequency Division Multiplexing) system, is analyzed through computer simulation. DMRS(Digital Microwave Radio System)is modeled as Rummler fading channel. In Simulation result, we known that the coding system improved about 3.6dB~10.5dB when BER is 10 $^3$and b is 0.1~0.2 in case of 16QAM(Qurdrature Amplitude Modulation). Also, we known that was improved about 19.7dB when the b is 0.1 and was demanded about 10.5dB when the b is 0.2 in case of 64QAM. we known that the soft decision improved about 2~0.9dB when the b is 0.1~0.2 in case of 16QAM and about 3.3~7.8dB in case of 64QAM. In the equalizer system, efficiency improved from the case of that Eb/No is more than 13dB.

A Study on PAR Improvement of OFDM system using SLM-PTS Combine Method and ETD-Turbo Code (SLM-PTS 결합기법 및 ETD-Turbo부호를 적용한 OFDM 시스템에서의 PAR 개선에 관한 연구)

  • Sung Tae-Kyung;Kim Dong-Seek;Cho Hyung-Rae
    • Journal of Navigation and Port Research
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    • v.29 no.8 s.104
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    • pp.755-761
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    • 2005
  • In this paper, we propose a high-speed adaptive PTS method which eliminates high PAR (Peak-to-Average Power Ratio) and we compare the proposed method with other conventional methods. In addition, we have designed a combined type SLM-PTS scheme to reduce PAR and evaluate the performance. The system used for evaluating PAR performance can be constructed as COFDM (Coded Orthogonal Frequency Division Multiplexing) applying ETD(Enhabced Time Diversity)-Turbo coding scheme. All the analyses in this paper are focused on the system characteristics according to IFFT's point and modulation method and the performance evaluation are based on the PAR reduction rates. As a result, the SLM-PTS combination method reveals good PAR reduction rate and remarkable reduction in the amount of calculations. Especially, in the case of combine-3 scheme, we can achieve approximately $3.7\~3.9$ dB PAR reduction on a basis of 10-5 BER level. Moreover, we can eliminate the side information in COFDM system because of its adaptive characteristics in evaluating PAR reduction rate, so that the additional errors can be omitted.

Reduction of Structural and Computational Complexity in IMD Reduction Method of the PTS-based OFDM Communication System (PTS 방식의 OFDM 통신 시스템에서 IMD 저감 기법의 복잡도와 계산량 저감)

  • Kim, Seon-Ae;Lee, Il-Jin;Baek, Gwang-Hoon;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.8A
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    • pp.583-591
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    • 2009
  • OFDM(orthogonal frequency division multiplexing) signal with high PAPR(peak to average power ratio) produces the nonlinear distortion and/or decreases down the power efficiency of HPA(high power amplifier). So, the IMD(inter-modulation distortion) reduction method was proposed to reduce the nonlinear distortion, which shows better BER(bit error rate) performance than the PAPR reduction methods. However, IMD reduction method has inherent problem which system complexity and processing time increases because the FFT(fast Fourier transform) processor is added in transmitter and decision criterion of IMD reduction method is computed in frequency domain,. In this paper, therefore, we propose a new IMD reduction method to reduce the computational complexity and structure of IMD computation. And we apply this proposed method into OFDM system using PTS(partial transmit sequence) scheme and compare the computational complexity between conventional and proposed IMD reduction method. This method can reduce the system size and computational complexity. Also, the proposed has almost same BER performance with the conventional IMD reduction method.

PAPR Reduction Method Using SLM-based WHT and DSI (SLM 기반 Walsh Hadamard 변환 및 DSI 기법을 이용한 PAPR 저감 기법)

  • Kim Sang-Woo;Kim Namil;Ryu Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.11 s.102
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    • pp.1147-1154
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    • 2005
  • In this paper, we propose some PAPR(Peak to Average Power Ratio) reduction methods using WHT(Walsh Hadamard Transform) to reduce high PAPR generated in OFDM system because of multi carrier modulation. These proposed methods are the methods which has additional PAPR reduction performance without a loss of bandwidth efficiency and a large increment of calculation complexity than common PAPR reduction methods by combining the WHT with some common methods. In this paper, we propose two PAPR reduction methods made by combining a SLM(Selective Mapping) and DSI(Dummy Sequence Insertion) with a WHT. From simulation result, we can find that the PAPR reduction methods using a WHT can get about 1 dB additional PAPR reduction performance than common PAPR reduction methods; they are SLM and DSI. And, because our proposed methods have not only PAPR reduction effect, but also frequency diversity effect, more stabile data transmission is possible in nonlinear HPA and multipath fading channel.