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

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
권호 표지
DOI QR코드

DOI QR Code

Comparison Study of Beam Pattern for FDD downlink CDMA Signals

FDD에서 하향링크 CDMA신호의 빔패턴 비교 연구

  • Published : 2007.02.28
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, the effects of transmit beamforming on downlink performance in DS-CDMA communication systems are investigated. The uplink and downlink in FDD systems use different carrier frequencies. If the downlink uses the same weighting vectors as the uplink, the antenna beam for downlink is formed with certain DOA shift and it thus affects the beamforming gain. So, the impacts of different frequencies on the downlink beam patterns are studied. One possible algorithm to convert uplink beamforming weights to downlink, which is called frequency-calibrated processing, is also evaluated to reduce the degradation of downlink performance due to different frequencies. Under frequency selective channels, the downlink chooses a PUPW beamforming scheme when the uplink employs a PPPW vectors. To form a beam pattern for a PUPW after combining the downlink PPPWs converted from the uplink PPPWs, three approaches are studied. One method is to consider only one dominant path and thus obtain a single main-beam. In the others, multiple-beams weighted with the magnitudes of all paths and equally weighted with all paths are constructed.

본 논문에서 는 DS-CDMA(direct sequence code division multiple access) 통신시스템에서 다중안테나를 이용한 송신 빔 형성이 하향 링크의 성능에 미치는 영향을 빔 패턴을 통하여 연구하고자 한다. FDD(frequency division duplex) 시스템에서 상향 링크와 하향 링크는 반송파 주파수를 다르게 사용한다. 하향 링크가 상향 링크와 일치하는 빔 형성 가중치들을 사용한다면, 하향 링크의 안테나 빔은 다소의 DOA(direction of arrival)차이 때문에 빔형성 이득에 있어서 영향을 받게 된다. 따라서 서로 다른 반송파 주파수가 하향 링크의 빔 형성 성능에 미치는 영향을 분석한다. 주파수 조정 처리 방법은 상향 링크의 빔형성 가중치로부터 하향 링크의 가중치로 변환을 가능하게 한다. 이 방법을 이용하여 상향 링크와 하향 링크의 주파수 차이에 의한 하향 링크의 성능 저하를 감소시킬 수 있다. 주파수 선택적 채널에서 상향 링크는 경로마다 하나의 가중치를 이용하여 PPPW(per path per weight) 빔형성을 만들고, 반면에 하향 링크는 사용자당 가중치를 한 개만 사용하는 PUPW(per user per weight) 벡터를 이용한다. 상향 링크 PPPW 가중치들로부터 하향 링크 PUPW를 위한 하나의 빔 패턴을 형성하기 위해서 세 가지 방법을 고려한다. 첫째는 신호의 세기가 가장 큰 경로만을 이용한다. 둘째는 모든 경로들에게 각각의 크기에 비례하는 가중치를 할당하여 다중 빔들을 결합하여 하나의 빔을 형성한다. 셋째는 모든 경로들에게 같은 크기의 가중치를 할당하여 다중 빔들을 결합한다.

Keywords

References

  1. A. F. Naguib, 'Adaptive antennas for CDMA wireless networks,' Ph.D. dissertation, Stanford Univ., CA, Aug. 1996
  2. R. Kohno, 'Spatial and temporal communication theory using adaptive antenna array,' IEEE Personal Commun. Mag., vol. 5, pp. 28-35, Feb. 1998 https://doi.org/10.1109/98.656157
  3. J. C. Liberti, Jr. and T. S. Rappaport, Smart antennas for wireless communications: 1S-95 and Third generation CDMA Applications. Upper Saddle River NJ: Prentice Hall, 1999
  4. M. Dell'Anna and A. H. Aghvami, 'Performance of optimum and suboptimum combining at the antenna array of a W-CDMA system,' IEEE JSAC, vol. 17, no. 12, pp.2123-2137, Dec. 1999
  5. R. M. Buehrer, A. G. Kogiantis, S. Liu, J. Tsai and D. Uptegrove, 'Intelligent antennas for wireless communications-uplink,' Bell Labs Technical Journal, pp. 73-103, July-Sept. 1999
  6. S. Tanaka, A. Harada, M. Sawahashi and F. Adachi, 'Experiments on coherent adaptive antenna array diversity for wideband DS-CDMA mobile radio,' IEEE JSAC, vol. 18, no. 8, pp. 1495-1504, Aug. 2000
  7. A. F. Naguib, A. Paulraj, and T. Kailath, 'Capacity improvement with base station antenna array in cellular CDMA,' IEEE Trans. Veh. Technol., vol. 43, no. 3, pp. 691-698, Aug. 1994 https://doi.org/10.1109/25.312780
  8. D. Gerlach and A. Paulraj, 'Adaptive transmitting antenna arrays with feedback,' IEEE Signal Processing Lett., vol. 1, pp. 150-152, Oct. 1994 https://doi.org/10.1109/97.329842
  9. G. Xu and H. Liu, 'An efficient transmission beamforming scheme for frequency-division- duplex digital wireless communication systems,' Proc. Int. Conf. ASSP, Detroit, MI, May 1995, pp. 1729-1732
  10. Y.-C. Liang, F. Chin and K. J. R. Liu, 'Downlink beamforming for DS-CDMA mobile radio with multimedia services,' IEEE Trans. Commun., vol. 49, no. 7, pp. 1288-1298, July 2001 https://doi.org/10.1109/26.935169
  11. Y.C. Liang and F. Chin, 'Downlink channel covariance matrix (DCCM) estimation and its applications in wireless DS-CDMA systems,' IEEE JSAC, vol. 19, no. 2, pp. 222-232, Feb. 2001
  12. Y.-C. Liang and F. Chin, 'Two suboptimal algorithms for downlink beamforming in FDD DS-CDMA mobile radio,' IEEE JSAC, vol. 19, no. 7, pp. 1264-1275, July 2001
  13. H.-J. Li and T.-Y. Liu, 'Comparison of beamforming techniques for W-CDMA communications systems,' IEEE Trans. Veh. Technol., vol. 52, no. 4, pp. 752-760, July 2003 https://doi.org/10.1109/TVT.2002.804864
  14. K. S. Kim, I. Song, S. C. Bang and T.-J. Kim, 'Performance analysis of forward link beamforming techniques for DS/CDMA systems using base station antenna arrays,' IEEE Trans. Signal Processing, vol. 48, no. 3, pp. 862-865, March 2000 https://doi.org/10.1109/78.824680
  15. H. Taoka, S. Tanaka, T. Ihara and M. Sawahashi, 'Adaptive antenna array transmit diversity in FDD forward link for W-CDMA and broadband packet wireless access,' IEEE Wirel. Commun., vol. 9, issue 2,pp.34-41, April 2002 https://doi.org/10.1109/MWC.2002.998523
  16. K. I. Pedersen, P. E. Mogensen and J. Ramiro-Moreno, 'Application and performance of downlink beamforming techniques in UMTS,' IEEE Commun. Mag., vol. 41, issue: 10, pp. 134-143, Oct. 2003
  17. F. Adachi, 'Effects of orthogonal spreading and Rake combining on DS-CDMA forward link in mobile radio,' IEICE Trans. Commun., vol. E80-B, no. 11, pp. 1703-1712, Nov. 1997
  18. S. Kim, Y. Kwon and B. Kang, 'Performance analysis of downlink beamforming in FDD DS-CDMA systems,' accepted as a letter in IEICE Trans. Commun., Nov. 2006
  19. M.-H. Fong, V. K. Bhargava and Q. Wang, 'Concatenated orthogonal/pN spreading sequences and their application to cellular DS-CDMA systems with integrated traffic,' IEEE JSAC, vol. 14, no. 3, pp. 547-558, April 1996
  20. O. Awoniyi, N. B. Mehta and L. J. Greenstein, 'Characterizing the orthogonality factor in W-CDMA downlinks,' IEEE Trans. Wireless Commun., vol. 2, no. 4, pp. 621-625, July 2003
  21. M. Shokair and Y. Akaiwa, 'Performance of feedback-type adaptive array antenna in FDD system with rake receiver,' IEICE Trans. Commun., vol. E89-B, no. 2, pp. 539-544, Feb. 2006 https://doi.org/10.1093/ietcom/e89-b.2.539
  22. K. Huang, F. Adachi and Y. H. Chew, 'A more accurate analysis of interference for Rake combining on DS-CDMA forward link in mobile radio,' IEICE Trans. Commun., vol. E88-B, no. 2, pp. 654-663, Feb. 2005 https://doi.org/10.1093/ietcom/E88-B.2.654