한국정보통신학회논문지 (Journal of the Korea Institute of Information and Communication Engineering)

  • 제22권12호
  • /
  • Pages.1684-1690
  • /
  • 2018
  • /
  • 2234-4772(pISSN)
  • /
  • 2288-4165(eISSN)
한국정보통신학회 (The Korea Institute of Information and Commucation Engineering)
권호 표지
DOI QR코드

DOI QR Code

근접한 이중대역 신호에 대한 디지털 전치왜곡 기법

Digital Predistortion for Closely Spaced Dual-Band Signals

  • Jeong, Eui-Rim (Department of Information and Communication Engineering, Hanbat National University) ;
  • Oh, Joo-Hyun (Research Center of Communication and Electronic Warfare, LIG Nex1) ;
  • Kim, Do-Kyoung (Research Center of Communication and Electronic Warfare, LIG Nex1)
  • 투고 : 2018.10.25
  • 심사 : 2018.11.05
  • 발행 : 2018.12.31
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

근접한 이중대역 신호에 대한 새로운 디지털 전치왜곡 기법을 제안한다. 본 논문에서 고려하는 시스템은 이중대역 신호를 한 개의 전력증폭기로 증폭하는 송신기이다. 이 경우 전력증폭기 출력신호는 두 대역 신호의 교차변조 및 상호변조에 의해 왜곡이 발생한다. 특히 두 대역이 가까울 때에는 각 대역에서 상호변조에 의해 발행한 스펙트럼이 서로 겹칠 수 있고 이는 전치왜곡 성능을 저하시킨다. 이러한 문제를 해결하기 위해서 제안하는 기법은 먼저 전력증폭기 특성을 추정하고 이렇게 추정한 전력증폭기 특성을 바탕으로 전치왜곡 계수를 추출한다. 이러한 두 단계를 통해 전치왜곡 계수를 구하면 근접한 이중대역 신호에 대해서도 서로 간섭 없이 전치왜곡이 동작할 수 있다. 제안하는 기법은 컴퓨터 모의실험을 통해 검증하는데, 모의실험 결과에 따르면 제안하는 기법이 기존의 이중대역 전치왜곡 방법보다 우수한 성능을 보인다.

A new digital pre-distortion (DPD) technique for closely spaced dual-band signals is proposed. In the system under consideration, dual-band signals are amplified by a single broadband power amplifier (PA) at a transmitter. The PA output is distorted by cross-modulation between the two bands as well as their own inter-modulation distortion. Especially, if the two bands are placed in close proximity to each other, their spectral regrowths due to in-band intermodulation overlap with each other, which degrades DPD performance. To solve this problem, we propose a new DPD technique where the dual-band PA characteristics are estimated first, and then the DPD parameters are obtained from the estimated PA characteristics. By finding the DPD parameters through two steps, pre-distortion can perform well for the closely-spaced dual band signals. The proposed technique is verified through computer simulation. Simulation result shows that the proposed method performs better than the conventional method for closely-spaced dual band signals.

키워드

HOJBC0_2018_v22n12_1684_f0001.png 이미지

Fig. 1 architecture of proposed DPD for closely spaced dual-band signals

HOJBC0_2018_v22n12_1684_f0002.png 이미지

Fig. 2 DPD coefficient extraction from identified PA characteristics

HOJBC0_2018_v22n12_1684_f0003.png 이미지

Fig. 3 Memory PA model for simulation

HOJBC0_2018_v22n12_1684_f0004.png 이미지

Fig. 4 Spectrums of feedback signal and identified PA output for Band1(up) and Band2(down).

HOJBC0_2018_v22n12_1684_f0005.png 이미지

Fig. 5 PA output spectrum after applying DPD.

Table. 1 Summary of recursive least squares for PA identification

HOJBC0_2018_v22n12_1684_t0001.png 이미지

Table. 2 Improvement of spectral regrowth

HOJBC0_2018_v22n12_1684_t0002.png 이미지

참고문헌

  1. Y. Liu, J. J. Yan, and P. M. Asbeck, "Concurrent dual-band digital predistortion with a single feedback loop," IEEE Transactions on Microwave Theory and Techniques, vol. 63, no. 5, pp. 1556-1568, May 2015. https://doi.org/10.1109/TMTT.2015.2417158
  2. S. A. Bassam, W. Chen, M. Helaoui, and F. M. Ghannouchi, "Transmitter architecture for CA," IEEE Microwave Magazine, vol. 14, no. 5, pp. 78-86, March 2013. https://doi.org/10.1109/MMM.2013.2259399
  3. S. Amin, Z. A. Khan, M. Isaksson, P. Händel, and D. Ronnow, "Concurrent dual-band power amplifier model modification using dual two-tone test," Proceeding of European Microwave Conference, London, UK, pp. 186-189, 2016.
  4. J. Yi, Y. Yang, M. Park, W. Kang, and B. Kim, "Analog predistortion linearizer for high-power RF amplifiers," IEEE Transactions on Microwave Theory and Techniques, vol. 48, no. 12, pp. 2709-2713, Dec. 2000. https://doi.org/10.1109/22.899034
  5. A. Katz, J. Wood, and D. Chokola, "The evolution of PA linearization," IEEE Microwave Magazine, vol. 17, no. 2, pp. 32-40, Feb. 2016. https://doi.org/10.1109/MMM.2015.2498079
  6. X. Feng, B. Feuvrie, A. S. Descamps, and Y. Yang, "Digital predistortion method combining memory polynomial and feed-forward neural network," Electronics Letters, vol. 51, no. 12, pp. 943-945, June 2015. https://doi.org/10.1049/el.2015.0276
  7. S. Choi ; E. -R. Jeong, and Y. H. Lee, "A direct learning structure for adaptive polynomial-based predistortion for power amplifier linearization," 2007 IEEE 65th Vehicular Technology Conference, Dublin, Ireland, pp. 1791-1795, 2007.
  8. J. H. Kim, and R. S. Reddy, "Implementation of Mobile Apps Across Globe and Challenge to Software Engineering," Asia-pacific Journal of Convergent Research Interchange, HSST, vol. 1, no. 3, pp. 1-16, Sept. 2015.
  9. S. -M. Kim, "Nonlinearity detection and compensation in radio over fiber systems using a monitoring channel," Journal of information and communication convergence engineering, vol. 13, no. 3, pp. 167-171, Mar. 2015. https://doi.org/10.6109/jicce.2015.13.3.167
  10. P. Roblin, "Concurrent linearization: The state of the art for modeling and linearization of multiband power amplifiers," IEEE Microwave magazine, vol. 14, no. 7, pp. 75-91, July 2013. https://doi.org/10.1109/MMM.2013.2281297
  11. S. A. Bassam, M. Helaoui, and F. M. Ghannouchi. "2-D digital predistortion (2-D-DPD) architecture for concurrent dual-band transmitters," IEEE Transactions on Microwave Theory and Techniques, vol. 59, no. 10, pp. 2547-2553, Oct. 2011. https://doi.org/10.1109/TMTT.2011.2163802
  12. K. P. Lee, M. S. Yun, B. M. Jeong, and E. R. Jeong, "Digital Predistortion for Concurrent Dual-Band Transmitter Based on a Single Feedback Path," Journal of the Korea Institute of Information and Communication Engineering, vol. 21, no. 3, pp. 499-508, Mar. 2017. https://doi.org/10.6109/jkiice.2017.21.3.499
  13. Y. Liu, "Novel multiband linearization technique for closely-spaced dual-band signals of wide bandwidth," Proceeding of International Microwave Symposium (IMS), Phoenix, AZ, pp. 1-4, 2015.
  14. S. S. Haykin, Adaptive filter theory, 5-th ed. New Jersey, Pearson, 2013.
  15. A. A. M. Saleh, "Frequency-independent and frequency-dependent nonlinear models of TWT amplifiers," IEEE Transactions on communications, vol. 29, no. 11, pp. 1715-1720, Nov. 1981. https://doi.org/10.1109/TCOM.1981.1094911