Journal of Advanced Navigation Technology (한국항행학회논문지)

The Korean Navigation Institute (한국항행학회)
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PAPR Improvement of OFDM-CQAM System Through Optimum Position Impulse Insertion Scheme in Frequency Domain

주파수영역 최적 위치 임펄스 삽입기법에 의한 OFDM-CQAM 시스템의 PAPR 개선

  • Kwak, Jae-Min (Division of Navigational Information System, Mokpo National Maritime University)
  • 곽재민 (목포해양대 항해정보시스템학부)
  • Received : 2019.05.08
  • Accepted : 2019.06.25
  • Published : 2019.06.30
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Abstract

OFDM is popular digital communication method due to its immunity to multipath fading and capability of high speed data transmission, but it has disadvantage of high PAPR in transmission signal when many subcarrier modulated signal are added to the same phase. When frequency domain high amplitude impulse is inserted before IFFT in OFDM transmitter, the PAPR of OFDM signal in tme domain can be effectively reduced. In this paper, the degree of PAPR improvement of OFDM communication system with CQAM subcarrier modulation is analysed by adopting impulse insertion technique before IFFT of transmitter. Furthermore, it is verified that additional PAPR performance improvement can be obtained by finding optimum position of impulse insertion for maximizing PAPR reduction. Through computer simulation, the degree of PAPR improvement according to amplitude and position of inserted impulse is superior to conventional technique in OFDM-CQAM system.

OFDM (orthogonal frequency division multiplexing)은 다중경로 페이딩에 강하고 고속전송이 가능하다는 장점으로 널리 사용되고 있는 디지털 통신방식이나, 여러 부반송파 변조신호가 동위상으로 겹쳐지면서 송신신호의 PAPR (peak to average power ratio)이 높아진다는 단점을 가지고 있다. 송신단의 IFFT (inverse fast Fourier transform) 이전에 주파수 영역에서 높은 크기의 임펄스를 삽입하면, 쌍대성 특성으로 인해 시간영역의 OFDM 신호의 PAPR 감소 효과를 가져올 수 있다. 본 논문에서는 CQAM (cross quadrature amplitude modulation) 방식을 채용하는 OFDM 통신시스템에서 송신단의 IFFT 이전에 임펄스를 삽입함으로서 개선되는 PAPR 성능을 분석한다. 또한 PAPR을 최소화시킬 수 있는 최적의 임펄스 삽입위치 찾아내고 이를 적용하였을 경우의 PAPR 개선효과를 검증한다. 컴퓨터 시뮬레이션을 통해 주파수영역에서 삽입되는 임펄스 크기와 위치에 따라 OFDM-CQAM 시스템의 PAPR 개선효과가 기존 방식에 비해 우수함을 확인한다.

Keywords

References

  1. K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE and WiMAX, 2nd ed. West Sussex:UK, Wiley, 2008.
  2. L. Yang, Y. M. Siu, K. K. Soo, S. W. Leung, S. Q. Li, " Low-complexity PAPR reduction technique for OFDM systems using modified widely linear SLM Scheme," International Journal of Electronics and Communications, Vol. 66, No. 12, pp. 1006-1010, Dec. 2012. https://doi.org/10.1016/j.aeue.2012.05.003
  3. C. L. Zhao, D. Q. Liu, X. B. Sun, T. Jiang, “Deepen spectrum notch and reduce PAPR in OFDM systems via combining subcarriers precoding with tone reservation,” The Journal of China Universities of Post Telecommunications, Vol. 18, No. 3, pp. 80-84, June 2011. https://doi.org/10.1016/S1005-8885(10)60067-2
  4. Abdulrahman Ikram Siddiq, “PAPR reduction in OFDM systems using peak insertion,” International Journal of Electronics and Communications, Vol. 69, No. 2, pp. 573-578, Feb. 2015. https://doi.org/10.1016/j.aeue.2014.11.009
  5. J. Armstrong, "Peak-to-average power reduction for OFDM by repeated clipping and frequency domain filtering," IEEE Electronics Letters, Vol. 38, No. 5, pp. 246-247, Feb. 2002. https://doi.org/10.1049/el:20020175
  6. H. Ochiai and H. Imai, "Performance analysis of deliberately clipped OFDM signals", IEEE Trans. on Communications, Vol. 50, No. 1, pp. 89-101, Jan. 2002. https://doi.org/10.1109/26.975762
  7. A. E. Jones, T. A. Wilkinson and S. K. Barton, "Block coding scheme for reduction of peak to mean envelope power ratio of multicarrier transmission schemes", Electronics Letters, Vol. 30, No. 25, pp. 2098-2099, Dec. 1994. https://doi.org/10.1049/el:19941423
  8. S. H. Muller and J. B. Huber, "OFDM with reduced peak to average power ratio by optimum combination of partial transmit sequences," Electronics Letters, Vol. 33, No. 5, pp. 368-369, Feb. 1997. https://doi.org/10.1049/el:19970266
  9. M. Chauhan, and A. Chobe "PAPR Reduction in OFDM system using tone reservation technique," IJCTEE, Vol. 2, No. 4, pp. 57- 60, Aug. 2012.
  10. M. Petermann, D. Wubben and K. Kammeyer "Joint constellation extension and tone reservation for PAPR reduction in adaptive OFDM systems," IEEE 10th Workshop on Signal Processing Advances in Wireless Communications, pp. 439-443, June 2009.
  11. A. Ghassemi and T. A. Gulliver, “Partial selective mapping OFDM with low complexity IFFTs,” IEEE Communication Letters, Vol. 12, No. 1, pp. 4-6, Jan. 2008. https://doi.org/10.1109/LCOMM.2008.071397
  12. J. G. Smith, "Odd-bit quadrature amplitude-shift keying," IEEE Trans. Commun., Vol.23, No. 3, pp. 385-389, Mar. 1975. https://doi.org/10.1109/TCOM.1975.1092806
  13. J. M. Kwak, "EVM based SNR estimation performance in cross QAM using selected constellation points," Journal of Advanced Navigation Technology, Vol. 16, No. 3, pp. 426-432, June 2012. https://doi.org/10.12673/jkoni.2012.16.3.426