A Study on A Mathematical Formulation of Protection Ratio and Its Calculation for Fixed Radio Relay System with Diversity

다이버시티를 갖는 고정 무선 중계 시스템에 대한 보호비의 수학적 표현과 계산에 대한 연구

  • 서경환 (강남대학교 전자공학과)
  • Published : 2006.04.01


In this paper, a mathematical formulation of protection ratio and its calculation method are suggested for a radio relay system with diversity techniques. The analysis of protection ratio and its physical meaning have been performed for the space or frequency diversity system, and in particular protection ratios are reviewed in terms of the parameters of diversity improvement factor, which comprises antenna gain, separation distance between antennas, frequency and its difference between carriers, and distance. As one of simulated results, the co-channel protection ratio of 60 dB is obtained for the space diversity system regarding 6.2 GHz, 60 km, 64-QAM, and 25 m between antennas, which gives 15 dB less than the co-channel protection ratio of the non-space diversity system. In addition, the co-channel protection ratio for the frequency diversity system gives 64 dB in case of frequency offset of 0.5 GHz under the same conditions as the space diversity system, which brings about 11 dB less than the co-channel protection ratio of non-frequency diversity system. In consequency, it is interesting to note that the space diversity system is less sensitive to interference in comparison to the frequency diversity system and provides better quality of service for a given interference.


  1. 서경환, 'M/W 채널 재배치를 위한 타 시스템 수용방안에 관한 연구', 한국전자통신연구원, 2003년 11월
  2. 서경환, '디지털 M/W 통신망의 동일 및 인접채널 허용 간섭 기준 연구', 한국전자통신연구원, 2004년 11월
  3. 서경환, '정량적 분석에 의한 M/W 통신망의 간섭 보호비 연구', 한국전자통신연구원, 2005년 11월
  4. ETSI TR 101 854, 'Derivation of receiver interference parameters useful for planning fixed service point-to-point systems operating different equipment classes and/or capacities', 2005
  5. Rec. ITU-R F. 758-3, 'Considerations in the development of criteria for sharing between the terrestrial fixed service and other services', 2004
  6. UK, 'Technical frequency assignment criteria', RA, Jun. 2003
  7. Australian Communications Authority(ACA), Microwave Fixed Service Frequency(RALI, FX3), 2003
  8. 서경환, 이주환, '고정 무선 중계 망의 간섭분석을 위한 보호비 계산에 대한 연구', 대한전자공학회논문지, 43(1), pp. 133-142, 2006년
  9. 서경환, '인접채널 간섭 분석을 위한 고정 무선 중계 시스템의 NFD 및 보호비 계산에 대한 연구', 한국전자파학회논문지, 16(11), pp. 1138-1146, 2005년 11월
  10. Rec. ITU-R P.530-10, 'Propagation data and prediction methods required for the design of terrestrial line-of-sight-systems', 2004
  11. Carlos Salema, Microwave Radio Links, John Wiley, 2003
  12. Roger L. Freeman, Radio System Design for Telecommunications, John Wiley &Sons, Inc., 1997
  13. A. Vigants, 'Space diversity engineering', Bell System Technical Journal, vol. 54, no. 1, pp. 103-142, 1975 https://doi.org/10.1002/j.1538-7305.1975.tb02828.x
  14. W. D. Rummler, 'A new selective fading model: application to propagation data', The Bell System Technical Journal, vol. 58, pp. 1037-1072, 1979 https://doi.org/10.1002/j.1538-7305.1979.tb03335.x
  15. A. A. R. Townsend, Digital Line-of-Sight Radio Links: A Handbook, Prentice-Hall, International(UK), 1988
  16. 서경환, '디지털 마이크로웨이브 링크 설계를 위한 전송품질 및 주파수 이전에 대한 연구', 한국전자파학회논문지, 14(5), pp. 489-498, 2003 년 5월
  17. Rec. ITU-R P.453-9, 'The radio refractive index: its formula and refractive data', 2004
  18. Rec. ITU-R F.1101, 'Characteristics of digital fixed wireless systems below about 17 GHz', 2004