• Title, Summary, Keyword: OFDM System

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Performance Comparison of the OFDM/SFH and OFDM/DS Systems in the Jamming Channel (OFDM/SFH와 OFDM/DS 시스템의 Jamming 채널에서 성능비교)

  • 박종현;김상우;유흥균;이상태
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1149-1155
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    • 2003
  • OFDM/SFH(orthogonal frequency division multiplexing/slow frequency hopping) system is the combination of OFDM communication system with frequency hopping(FH) method and OFDM/DS(orthogonal frequency division multiplexing/direct sequence) system combines the OFDM communication system with direct sequence(DS) method in terms of PN(pseudo noise) sequence. These two systems are also can be used for anti-jamming. In this study we analyze performances of OFDM/SFH system and OFDM/DS system with the equal information rate in partial band jamming and tone jamming channel. We find BER(bit error rate) in the variation of JFR(jamming fractional ratio) and JSR(jamming to signal power ratio) of the partial band jamming. Also, BER is found in the several JSR of the single tone or multi tone jamming. OFDM/DS system shows better performance than OFDM/SFH system in partial band jamming environment. OFDM/DS system has about 2.5 ㏈ SNR(signal to noise power ratio) gains than OFDM/SFH system when JFR=4/16 and JSR=0 ㏈ to meet BER=10$\^$-3/. However, OFDM/SFH system has about 3 ㏈ SNR gains than OFDM/DS system at single tone jamming of JSR=5 ㏈. In multi tone jamming, performance of OFDM/SFH system is considerably degraded than OFDM/DS system.

Comparison of Time and Frequency Resources of DFT-s-OFDM Systems Using the Zero-Tail and Unique Word (Zero Tail과 Unique Word를 사용하는 DFT-s-OFDM 시스템들의 시간과 주파수 자원 비교)

  • Kim, Byeongjae;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.12
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    • pp.1715-1720
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    • 2016
  • In the upcoming 5-generation mobile communication system, various techniques for improving the power efficiency and spectral efficiency have been proposed. 5G mobile communication system also have been studied a lot of multi-carrier-based modulation techniques like the 4G mobile communication system. In this paper, we analyzed the conventional system structure of the Zero-tail DFT-s-OFDM and UW (Unique Word) -DFT-s-OFDM system based on DFT-s-OFDM system in these techniques. UW and zero are added and used each system, and CP is removed. the result of quality of systems for simulation, OOB(Out of Band) power of Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM use the less time resource as long as CP length, also both systems are reduced about 11dB than DFT-s-OFDM system. In these result, Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM system are more effective than DFT-s-OFDM system.

Comparison Study of Long-haul 100-Gb/s DDO-OFDM and CO-OFDM WDM Systems

  • Liu, Ling;Xiao, Shilin;Bi, Meihua;Zhang, Lu
    • Journal of the Optical Society of Korea
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    • v.20 no.5
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    • pp.557-562
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    • 2016
  • In this paper, for the first time, the transmission performances of long-haul 100-Gb/s direct detection optical OFDM (DDO-OFDM) and coherent optical OFDM (CO-OFDM) wavelength division multiplexing (WDM) systems are compared by simulation. It provides specific guides for system parameter selection to get a high-performance and cost-effective OFDM WDM system. Specifically, the comparison involves three aspects: launched power is investigated to achieve better system performance; laser linewidth is numerically investigated to choose cost-effective laser; system dispersion tolerances with different laser linewidths are analyzed to further reveal the advantages and disadvantages of these two detecting methods, direct detection and coherent detection, in long-haul OFDM WDM system.

Performance Comparison of SFBC/SFTC-OFDM Systems Under MB-OFDM Interference (MB-OFDM UWB 신호 간섭하에서 SFBC/SFTC-OFDM 시스템들의 성능 비교)

  • Kim, Kyung-Seok;Song, Chang-Kun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10A
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    • pp.968-975
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    • 2006
  • Research about the mode of MIMO that can get a coding benefit at the same time with a diversity benefit using a multiple antenna at the fading channel for a high-speed data transmission have been processed actively But the analysis about the interference of UWB system comes not to consist yet. So this paper analyzed the performance of the interference of UWB system to SFBC-OFDM and SFTC-OFDM system that applied a space block code which has a space diversity characteristic to OFDM system at MIMO channel. We shelved the performance that SFTC-OFDM system is robuster than SFBC-OFDM system under MB-OFDM UWB Interference.

OFDM/OQAM-IOTA System (OFDM/OQAM-IOTA 시스템)

  • Zhou, Xiao;Heo, Joo;Chang, KyungHi
    • The Journal of Advanced Navigation Technology
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    • v.8 no.2
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    • pp.120-128
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    • 2004
  • Although conventional OFDM/QAM modulation scheme using guard interval is robust to channel induced ISI (Inter-Symbol Interference) in time-domain, it is very sensitive to ICI (Inter-Carrier Interference) due to doppler effect in frequency domain. OFDM/OQAM-IOTA modulation scheme utilizes IOTA (Isotropic Orthogonal Transform Algorithm) filter that has orthogonality in time and frequency domain so that it is robust to delay spread and doppler effect. OFDM/OQAM-IOTA system can increase bandwidth effeciency since it does not use guard interval. In this paper, we show the structure of OFDM/OQAM-IOTA and perfect channel estimation scheme for OFDM/OQAM-IOTA system. We also compare OFDM/OQAM-IOTA system and OFDM/QAM system in AWGN and 1-path Rayleigh fading channel. Simulation results show that OFDM/OQAM system outperforms OFDM/QAM system.

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A Study on the ZP-OFDM System Robust to Symbol Timing Offset (심볼 타이밍 옵셋에 강건한 ZP-OFDM 시스템에 관한 연구)

  • Chung, Jae-Pil
    • The Journal of Advanced Navigation Technology
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    • v.15 no.6
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    • pp.1042-1046
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    • 2011
  • In this paper, we analyze the STO (Symbol Timing Offset) problem in conventional ZP-OFDM (Zero Padding-Orthogonal Frequency Division Multiplexing) systems and propose a robust ZP-OFDM system with bi-directional overlap-add scheme to overcome the problem. The proposed ZP-OFDM system is able to preserve the orthogonality between subcarriers and reduce the interference from other ZP-OFDM symbols due to the BOA scheme, which exploits both ZP intervals of the previous and the current ZP-OFDM symbols, even though serious STOs result from inaccurate symbol timing synchronization. Simulation results verify that the proposed ZP-OFDM system is superior to the conventional ZP-OFDM system.

An Analysis of Multiuser Diversity Technology in the MIMO-OFDM System (MIMO-OFDM 시스템에서 다중사용자 다이버시티 기술의 성능분석)

  • Zhang, Ke;Suh, Hee-Jong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.6
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    • pp.1121-1128
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    • 2019
  • In this paper, we introduce the combination of OFDM(Orthogonal Frequency Division Multiplexing) and MIMO(Multiple-Input Multiple-Output) technology, and explain that this combination seems to be very preferable when designing very high-rate wireless mobile systems. The application of OFDM, with the block diagrams of an OFDM modulator and demodulator and a MIMO-OFDM system, are described. The several diversities are studied at the receiver, analyzed the performances of diversity in OFDM-MIMO system and simulated results.

Performance improvement of XCP-OFDM system using cross-handed circular polarization in frequency offset environments (주파수 오프셋 환경에서의 역선회 원편파를 이용한 XCP-OFDM 시스템의 성능 개선)

  • 김병옥
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.1
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    • pp.49-56
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    • 2004
  • An OFDM system using cross-handed circular Polarization(XCP-OFDM) is newly proposed in his paper. The proposed XCP-OFDM system divides the subchannels into a right-handed circular polarization(RHP channel and a left-handed circular polarization(LHCP) channel that alternate each other. Therefore, the overlaps between subcarriers in XCP-OFDM system can be reduced to a great extend compared to the conventional OFDM system. By this reason, it can improve the orthogonality and reduce the inter-channel interference due to frequency offset. In this paper, it can be seen that the proposed XCP-OFDM system shows robust against frequency offset.

Performance Comparison of OFDM Based on Fourier Transform and Wavelet OFDM Based on Wavelet Transform (웨이블릿 변환 기반의 Wavelet-OFDM 시스템과 푸리에 변환 기반의 OFDM 시스템의 성능 비교)

  • Lee, Jungu;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.3
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    • pp.184-191
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    • 2018
  • Orthogonal frequency division multiplexing(OFDM) is a multicarrier modulation(MCM) system that enables high-speed communications using multiple carriers and has advantages of power and spectral efficiency. Therefore, this study aims to complement the existing shortcomings and to design an efficient MCM system. The proposed system uses the inverse discrete wavelet transform(IDWT) operation instead of the inverse fast Fourier transform(IFFT) operation. The bit error rate(BER), spectral efficiency, and peak-to-average power ratio(PAPR) performance were compared with the conventional OFDM system through the OFDM system design based on wavelet transform. Our results showed that the conventional OFDM and Wavelet-OFDM exhibited the same BER performance, and that the Wavelet-OFDM using the discrete Meyer wavelet had the same spectral efficiency as the conventional OFDM. In addition, all systems of Wavelet-OFDM based on various wavelets confirm a PAPR performance lower than that of conventional OFDM.

Design and Performance Evaluation of Adaptive OFDM Communication System Robust to the Narrow-band Interference (협대역 간섭에 강한 적응형 OFDM 통신 시스템 설계와 성능 평가)

  • Jung Rag-Gyu;Kim Sun-Ae;Ryu Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.7
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    • pp.629-637
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    • 2006
  • It is important to design the high-speed communication system in the hostile channel. Due to the frequency diversity, FD-OFDM that can be used for the high-speed communication is more robust to the noise or interference than ordinary OFDM. However, even the FD-OFDM becomes degraded in th ε strong narrow band interference channel. In this paper, we propose an AFD-OFDM system and analyze the communication performances in order to find out the more robust communication system in the hostile channel. So, the AFD-OFDM system can cover the drawback of the FD-OFDM and improve the BER performance than FD-OFDM. From the simulation results, FD-OFDM shows better performance than the ordinary OFDM. Furthermore, AFD-OFDM shows more excellent performance than FD-OFDM in the strong narrow interference channel.