The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
권호 표지

PAPR Reduction Method for the Nonlinear Distortion in the Multicode CDMA System

멀티코드 CDMA 시스템에서 비선형 왜곡에 대처하는 PAPR 저감 기법

  • Kim Sang-Woo (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Kim Namil (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Kim Sun-Ae (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Suh Jae-Won (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Ryu Heung-Cyoon (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University)
  • Published : 2005.12.01
Download PDF
⟨ Previous Next ⟩

Abstract

Multi-code code division multiple access(MC-CDMA) has been proposed for providing the various service rates with different quality of service requirement by assigning multiple codes and increasing the capacity. However, it suffers from the serious problem of high peak to average power ratio(PAPR). So, it requires large input back-off, which causes poor power consumption in high power amplifier(HPA). In this paper, we propose a new method that can reduce PAPR efficiently by constraint codes based on the opposite correlation to the incoming information data in MC-CDMA. PAPR reduction depends on the length and indices of constraint codes in MC-CDMA system. There is a trade-off between PAPR reduction and the length of constraint codes. From the simulation results, we also investigate the BER improvement in AWGN channel with HPA. The simulation results show that BER performance can be similar with linear amplifier in two cases: 1) Using exact constraint codes without input back-off and 2) a few constraint codes with small input back-off.

Multi-code code division multiple access(MC-CDMA) 시스템은 다수의 코드 사용으로 인한 용량의 증가를 통해 다양한 속도, 다양한 품질의 서비스를 제공할 수 있다는 장점을 갖는다 그러나, 여러 개의 코드들이 합쳐지면서 PAPR(Peak to Average Power Ratio)이 크게 증가되므로 비선형 왜곡에 의한 시스템 성능이 크게 저하되고, 이를 위해 HPA(High Power Amplifier)에서 많은 양의 back-off를 해야 하므로 큰 전력 손실이 나타난다. 본 논문에서는 들어오는 정보 데이터에 상응하는, 즉 입력 데이터의 상관 관계에 의한 constraint code의 삽입함으로써 PAPR을 효율적으로 낮출 수 있는 방법을 제안한다. PAPR 저감 효과는 사용된 constraint code의 길이와 index에 의존하며, PAPR 저감 효과와 constraint code의 길이 사이에 trade-off가 존재한다. HPA 및 AWGN 채널을 고려한 시뮬레이션 결과에서, 1) Input back-off 없이 가능한 모든 constraint code를 사용해 신호를 선택한 경우와 2) 약간의 input back-off와 몇 가지 constraint code만을 이용해 신호를 선택한 경우에서, BER성능이 선형 HPA를 사용한 OFDM의 성능과 거의 같게 나타남을 확인할 수 있다.

Keywords

References

  1. T. F. Wong, T. M. Lok, 'Transmitter adaptation in multicode DS-CDMA systems', IEEE J. Select. Areas. Commun., vol. 19, no. 1, pp. 69-82, Jan. 2001 https://doi.org/10.1109/49.909610
  2. I. Chih-Lin, R. D. Gitlin, 'Multi-code CDMA wireless personal communication networks', IEEE ICC, pp. 1060-1064, 1995 https://doi.org/10.1109/ICC.1995.524263
  3. T. Ottoson, 'Precoding for minimization of envelope variations in multicode DS-CDMA systems', Wireless Personal Communications, vol. 13, pp. 57-78, May 2000 https://doi.org/10.1023/A:1008835513858
  4. T. Ottoson, 'Precoding in multicode DS-CDMA systems', Int. Symp. Info. Thy.(Ulm, Germany), IEEE, pp. 351, Jun. 1997 https://doi.org/10.1109/ISIT.1997.613282
  5. T. Ottoson, T. Palenius, 'The impact of using multicode transmission in the WCDMA system', IEEE Vehicular Technology Conference, IEEE, pp. 1550-1554, 1999
  6. K. G. Paterson, 'On codes with low peak-toaverage power ratio for multi code CDMA', IEEE Trans. on Information Theory, vol. 50, no. 3, pp. 550-559, Mar. 2004 https://doi.org/10.1109/TIT.2004.825505
  7. K. G. Paterson, 'On codes with low peak-to-average power ratio for Multi-Code CDMA', Tech. Rep. HPL-2001-115, HP Laboratories, Bristol, UK, 2001
  8. K. Paterson, 'Sequences for OFDM and multi-code CDMA: Two problems in algebraic coding theory', Tech. Rep. HPL-2001-146, HP Laboratories, Bristol, UK, 2001
  9. K. Sathananthan, C. Tellambura, 'Peak-to-average power ratio analysis in multicode CDMA', IEEE Vehicular Technology Conference, IEEE, vol. 1, pp. 500-504, Sep. 2002 https://doi.org/10.1109/VETECF.2002.1040394
  10. N. Guo, L. B. Milstein, 'Uplink performance evaluation of multicode DS-CDMA systems in the presence of nonlinear distortions', IEEE J. Select. Areas. Commun., vol. 18, pp. 1418-1428, Aug. 2000 https://doi.org/10.1109/49.864007
  11. N. Guo, L. B. Milstein, 'The impact of nonlinear amplification on multi-code CDMA systems', IEEE ICC, pp. 1034-1038, 2000 https://doi.org/10.1109/ICC.2000.853655
  12. J. Tellado, J. M. Cioffi, 'Efficient algorithms for reducing PAR in multicarrier systems', IEEE International Symposium on Information Theory, pp. 191, Aug. 1998 https://doi.org/10.1109/ISIT.1998.708789
  13. I. Chih-Lin, G. P. PoHini, L. Ozarow, and R. D. Gitlin, 'Performance of multi-code CDMA wireless personal communications networks', IEEE Vehicular Technology Conference, vol. 2, pp. 907-911, Jul. 1995
  14. F. Adachi, M. Sawahashi, and H. Suda, 'Wideband DS-CDMA for next-generation mobile communications systems', IEEE Commun. Mag., vol. 36, pp. 56-69, Sep. 1998