Journal of the Institute of Electronics and Information Engineers (전자공학회논문지)

The Institute of Electronics and Information Engineers (대한전자공학회)
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Estimation of I/Q Imbalance Parameters for Repeater using Direct Conversion RF with Low Pass Filter Mismatch

저역 통과 필터 불일치를 포함한 직접 변환 RF 중계기의 I/Q 불균형 파라미터 추정

  • Yun, Seonhui (LIG Nex1) ;
  • Lee, Kyuyong (A2U Information & Communications Technology) ;
  • Ahn, Jaemin (Department of Information Communications Engineering, Chungnam National University)
  • Received : 2014.10.02
  • Accepted : 2015.02.03
  • Published : 2015.02.25
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Abstract

In this paper, we studied the method for analyzing and estimating the parameters that induce I/Q imbalance in the repeater using direct conversion RF. In repeater, amplitude, phase, and filter mismatch are generated in the receiving-end which converts RF signal to baseband signal. And amplitude and phase mismatch are generated in the transmitting-end which converts baseband signal to RF signal. Accordingly, we modeled the parameters that cause I/Q imbalance in the structure of the repeater in order, and proposed a feedback test structure from the transmitting-end to the receiving-end for estimating the corresponding parameters. By comparing the test transmitting signal and received signal, it is possible to estimate the I/Q imbalance parameters which occurred from mixed components of real and imaginary part. And it was confirmed that I/Q imbalance phenomenon has been properly compensated with estimated parameters at the direct conversion RF repeater.

본 논문에서는 직접 변환 방식을 사용하는 RF 중계기에서 I/Q 불균형을 유발하는 파라미터를 분석하고 이를 추정하기 위한 방법에 대하여 연구하였다. 중계기에서는 RF 신호를 기저 대역으로 변환하는 수신단에서 실수부와 허수부의 진폭, 위상 불일치 및 필터 불일치가 발생하며 기저 대역 신호를 RF 신호로 변환하는 송신단에서 진폭과 위상의 불일치가 발생하게 된다. 이에 따라 중계기 구조에서 I/Q 불균형이 발생하는 요소를 순서대로 모델링 하고, 해당 파라미터를 추정하기 위한 송신단에서 수신단으로의 피드백 시험 구조를 제안하였다. 시험 송신 신호와 수신 신호의 비교를 통해 각 실수부와 허수부 신호 성분이 섞이면서 발생한 I/Q 불균형 요소를 추정할 수 있음을 기술하였으며, 추정한 파라미터를 이용하여 직접 변환 RF 중계기에서 I/Q 불균형 현상이 적절히 보상되었음을 확인하였다.

Keywords

References

  1. Telecommunications Technology Association, (2014, Sep. 29). Repeater [Online]. Available: http://word.tta.or.kr/terms/terms.jsp.
  2. Seongjae Lee et al., "ICS(Interference Cancellation System) in Wireless Repeater Using Complex Singed Singed LMS Algorithm," J. IEEK, vol. 48.TC, no. 10, pp. 53-59, Oct. 2011.
  3. Asad A. Abidi, "Direct-Conversion Radio Transceivers for Digital Communications," IEEE J. Solid-State Circuits, vol. 30, no. 12, pp. 1399-1410, Dec. 1995. https://doi.org/10.1109/4.482187
  4. B. Razavi, RF Microelectronics, Prentice Hall, NJ, 1988.
  5. Younghwan Jin et al., "Additional Diversity Gain in OFDM Systems under the Influence of IQ Imbalances," J. KICS, vol. 31, no. 12A, pp. 1205-1212, Dec. 2006.
  6. James K. Cavers and Maria W. Liao, "Adaptive Compensation for Imbalance and Offset Losses in Direct Conversion Transceivers," IEEE Trans. Veh. Technol., vol. 42, no. 4, pp. 581-588, Nov. 1993. https://doi.org/10.1109/25.260752
  7. Alireza Tarighat et al., "Compensation Schemes and Performance Analysis of IQ Imbalances in OFDM Receivers," IEEE Trans. Signal Process., vol. 53, no. 8, pp. 3257-3267, Aug. 2005. https://doi.org/10.1109/TSP.2005.851156
  8. Andreas Schuchert et al., "A Novel IQ Imblance Compensation Scheme for the Reception of OFDM Signals," IEEE Trans. Consum. Electron., vol. 47, no. 3. pp. 313-318, Aug. 2001. https://doi.org/10.1109/30.964115
  9. Yun-Jeong Song et al., "A Joint Scheme for AGC and I/Q Imbalance Compensation at QPSK Demodulator," J. IEEK, vol. 41.IE, no. 3, pp. 53-60, Sep. 2004.
  10. Hyung Chul Park, "A Quantitative Analysis of I/Q Regeneration and I/Q Mismatch in Multi-Port Junction-based Direct Receivers," J. IEIE, vol. 49, no. 9, pp. 145-153, Sep. 2012.
  11. Kenneth M. Gainey and James Arthur Proctor, Jr., "IQ Imbalance Compensation in Interference Cancellation Repeter using a Zero-IF Radio Architecture," U.S. Patent 12/940,697, May 10, 2012.
  12. Seonhui Yun and Jaemin Ahn, "I/Q Imbalance Compensation Method for the Direct Conversion Receiver with Low Pass Filter Mismatch," J. IEIE, vol. 51, no. 11, pp. 2401-2408, Nov. 2014.