• Title/Summary/Keyword: Phase Diversity

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Analysis of Phase Noise Effects in OFDM Transmit Diversity Systems (OFDM 송신 다이버시티 시스템에서의 위상잡음 영향 분석)

  • Lee, Jong-Gil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.2
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    • pp.243-249
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    • 2006
  • In this paper, the phase noise effects of OFDM transmission diversity systems were analyzed. Since OFDM communication system is very sensitive to phase noise, the system performance may degrade seriously due to the increase of subcarrier interferences and system noise. Therefore, The phase noise model was suggested and its distribution and power were varied to investigate the effects of phase noise on the system performance. The degree of the system performance degradation depends on the specific diversity structures of transmission systems. Here, the performances of OFDM systems with two and three antennas transmission diversity were analyzed and compared with that of systems without transmission diversity as the phase noise characteristics varied.

Analysis of Phase Noise Effects in OFDM Systems Using Transceiver Diversity (송수신 다이버시티를 적용한 다중 반송파 시스템에서의 위상잡음 영향 분석)

  • Lee, Jong-Gil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.2
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    • pp.280-286
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    • 2007
  • In this paper, the phase noise effects of OFDM transceiver diversity systems were analyzed. Since OFDM communication system is very sensitive to phase noise, the system performance may degrade seriously due to the increase of subcarrier interferences and system noise. Therefore, the phase noise model was suggested and its distribution and power were varied to investigate the effects of phase noise on the system performance. The degree of the system performance degradation depends on the specific diversity structures of transceiver systems. Here, the performances of OFDM systems with two antennas transceiver diversity were analyzed and compared with that of systems with only transmission diversity and without diversity as the phase noise characteristics varied.

The Combined Tx. Diversity of STBC Tx. Diversity and Balanced Tx. Diversity (STBC 송신 다이버시티와 균등 송신 다이버시티가 결합된 송신 다이버시티)

  • Chun, Kwang-Ho;Min, Seung-Hyun;Liu, Lijun;Lim, Myoung-Seob
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.2A
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    • pp.183-190
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    • 2008
  • The balanced Tx diversity with same data on two antennas can have better or lower performance than STBC Tx diversity, depending on the difference between each phase of two channels when the received signal is processed with MRRC. Therefore, using the feedback information based on the phase estimation in each channels, the better scheme of the balanced Tx diversity and STBC Tx diversity can be selected. However, when the phase condition changes during the transmission as the selected Tx. diversity scheme, the decoded bit can be erroneous because the previously estimated phase and newly estimated phase is different. In this case, the receiver should request the re-transmission of the just received signal to the transmitter part. Through computer simulation, it is shown that the combined scheme of the balanced Tx diversity and STBC Tx. diversity has better performance than STBC Tx diversity.

New Evaluation on Maximum Ratio Diversity Reception for the Detection of Signals over Correlated Nakagami Fading Channels

  • Hong Wan-Pyo;Kim Chang-Hwan
    • Journal of information and communication convergence engineering
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    • v.2 no.3
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    • pp.145-148
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    • 2004
  • The performances of M-ary signals using L-branch maximum ratio combining (MRC) diversity reception in correlated Nakagami fading channels are derived theoretically. The coherent reception of M-ary differential phase shift keying (MDPSK), phase shift keying (MPSK), and quadrature amplitude modulation (MQAM) is considered. It is assumed that the fading parameters in each diversity branch are identical. The general formula for evaluating symbol error rate (SER) of M-ary signals in the independent branch diversity system is presented using the integral-form expressions.

Improving the Capture-range Problem in Phase-diversity Phase Retrieval for Laser-wavefront Measurement Using Geometrical-optics Initial Estimates

  • Li, Li Jie;Jing, Wen Bo;Shen, Wen;Weng, Yue;Huang, Bing Kun;Feng, Xuan
    • Current Optics and Photonics
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    • v.6 no.5
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    • pp.473-478
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    • 2022
  • To overcome the capture-range problem in phase-diversity phase retrieval (PDPR), a geometrical-optics initial-estimate method is proposed to avoid a local minimum and to improve the accuracy of laser-wavefront measurement. We calculate the low-order aberrations through the geometrical-optics model, which is based on the two spot images in the propagation path of the laser, and provide it as a starting guess for the PDPR algorithm. Simulations show that this improves the accuracy of wavefront recovery by 62.17% compared to other initial values, and the iteration time with our method is reduced by 28.96%. That is, this approach can solve the capture-range problem.

A Study on the Phase Diversity and Optimal I/Q Signal Combining Methods on a UHF RFID Receiver (UHF RFID 수신기의 위상 다이버시티 및 최적 I/Q 신호 결합 방법에 관한 연구)

  • Jang, Byung-Jun;Song, Ho-Jun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.4
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    • pp.442-450
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    • 2008
  • In this paper, the phase diverisity in a direct-conversion receiver for a UHF RFID reader is analyzed and the optimal I/Q signal combining methods is presented with respect to tag modulation. At first, fading characteristics of a single channel receiver is shown to prove the importance of phase diversity due to the phase relationship between the backscattered signal and the local oscillator. And the optimal signal combining methods are presented in order to overcome the signal power reduction due to phase diversity. In case of ASK, the power combining method is presented for the optimal I/Q combining. And the arctangent and principal component combining methods using covariance matrix of I and Q channels are presented for the optimal I/Q combining in case of PSK. In order to analyze the performance of suggested methods, the selection diversity and the optimal combining methods are compared. According to analysis and simulation results, the optimal combining methods have a maximum 3 dB SNR enhancement than selection diversity.

Comparisons on Diversity Techniques for SC-FDE Systems (SC-FDE 시스템에서의 다이버시티 기술 비교)

  • Rim, Min-Joong;Kim, Hong-Seog
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10A
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    • pp.964-971
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    • 2008
  • This paper compares the performances of cyclic delay diversity and phase rolling techniques for SC-FDE(Single Carrier with Frequency Domain Equalization) systems with multiple transmit antennas assuming time-flat and frequency-flat channels. In OFDM(Orthogonal Frequency Division Multiplexing) systems generation of time varying channels using phase rolling can result in performance gains comparable to those of frequency-selective channels made by cyclic delay diversity However, in SC-FDE systems making time-selective channels may produce better results than creation of frequency-selective channels.

A Simple If In-Phase Combiner and Its Performance for Point-to-Point Radio Relay System with Space Diversity

  • Suh Kyoung-Whoan
    • Journal of electromagnetic engineering and science
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    • v.5 no.1
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    • pp.1-7
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    • 2005
  • The implementation of a simple analog in-phase combiner is presented for a high capacity radio relay system with space diversity. It provides good performance in terms of simple hardware and easy control, and measured results are in good agreement with simulated ones. To suggest practical applications, signatures with/without diversity are measured for STM-1 signal of 64-QAM radio relay system combined with a 13-tap equalizer, and they provided more than 25 dB fade depth at 10$^{-3}$ BER under the frequency selective fading condition.

Performance Analysis of DS-CDMA System of Phase Estimation Error for Mobile Satellite Wireless Communication Channel (이동위성 무선통신 채널에서 위상추정 에러가 있는 DS-CDMA 시스템의 성능 해석)

  • Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.11 no.2
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    • pp.170-176
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    • 2007
  • In this paper, we improve performance for system when the carrier recovery signal is not perfect in the multipath mobile wireless communication fast fading channel based on DS-CDMA system. In the case, we use the phase estimation, diversity and adaptive FEC code technique in order to overcome this carrier phase error and mobile wireless fading. As a results in DS-CDMA system, we know that the appropriate use of diversity and adaptive FEC code technique reduced considerably performance degradation due to phase error.

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Analysis of Phase Noise Effects in Transceiver Diversity Systems (송수신 다이버시티 시스템에서의 위상잡음 영향 분석)

  • Lee Seung-Ryong;Lee Jong-Gil
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2006.05a
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    • pp.643-646
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    • 2006
  • The popularity of OFDM systems is being increased because of high speed data transmission capability and the spectral efficiency characteristics. However, since OFDM systems are very sensitive to the phase noise, The interference among subcarriers and the total system noise can be increased seriously due to the degree of phase noise effects which can cause the orthogonality problems. Therefore, these phase noise effects were analyzed using the phase noise model by varying its parameters. Especially in this paper, The degree of system performance degradation was investigated for the OFDM systems applying the relatively simple transmit and receiver diversity.

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