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研究生(外文):Junn-Wei Ju
論文名稱(外文):Measurement and Analysis of Fading Phenomenon for Microwave Signals over Super Long Distance and Oversea Links
指導教授(外文):Miin-Jong Hao
外文關鍵詞:Fading PhenomenonMicrowave Signals over Super Long Distance
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In wireless communications, the atmosphere is used as a transmission medium. However, this free open medium varies frequently due to atmospheric anomalies. Recently, many technical papers have been reported the factors such as the meteorological conditions and reflectivity or refractivity in the effects of the performance of the radio system.
In this thesis we measure the signals received from a 265 kilometers line-of-sight over sea microwave radio link operating at 4 GHz. The data collection period is about 7 months. Our analytical results show that about 67.56 percent of transmission outage is related to the tidal variance, 62.16 percent correlated with the humidity and pressure, and 59.45 percent with the refractive index and temperature.
In long distance over sea propagation microwave links, severe fading occurs frequently, which often substantially impair the quality or reliability of the transmission system. The space diversity scheme has been used to deal with this problem.
In general, two methods are used in diversity schemes. The first one is to combine the two received signals by the phase combiner, and the other is to select the larger amplitude of the two received signals. The first method has been used prevalently for a long time. Although it obtained a combining gain, the combining signal amplitudes could be possibly pulled back with a long delay times between different paths. Hence even both signal magnitudes are strong, the effect of combing are limited. In order to solve this problem, we propose a second method to deal this problem by selecting largest amplitude. Our result shows that the improvement of the system availability is better than the first method, noticeably as the availability is below 99.95%.
Abstract in Chinese i
Abstract in English ii
Acknowledgment iv
Contents v
List of Figures and Tables vii
Chapter 1 Introduction 1
Chapter 2 Basic Principles 3
2.1 Radio rays reflection 4
2.2 Atmospheric Effects and Radio Ray bending 7
2.3 Anomalous propagation due to refractive index variated 10
2.4 Fresnel Zones 17
2.5 Multipath Fading 19
2.6 Designs of Microwave Radio Systems 21
2.6.1 Calculating the free-space loss 21
2.6.2 Calculating the flat fade margin 21
2.6.3 Evaluation of the antenna gain 22
2.6.4 Evaluation of the atmospheric gases attenuation 23 Evaluation of the attenuation of dry air 23 Evaluation of the attenuation of water vapor 24
2.6.5 Space-diversity improvement in radio systems 26
2.6.6 Outage prediction for systems using space diversity 28
2.6.7 Outage prediction of the systems using the frequency diversity 31
2.6.8 Prediction of the outage of using space combining with frequency diversities scheme 31 Two - receiver construction 31 Four - receiver construction 32
Chapter 3 Path Description and Equipment Parameters 34
Chapter 4 Measurement Results and Analysis 38
4.1 Definition of measurement criteria 38
4.2 Data analysis 39
4.3 The results of space diversity structures 60
4.4 The results of different diversity structures 65
Chapter 5 Conclusions 71
References 72
Appendix 74
[1].Jin-Teong Ong ; Chun-Feng Hu, “propagation measurements on an overwater line-of-sight link in Singapore” International Conference on Information, Communications and Signal Processing ICICS ‘97 Singapore, 9-12 September 1997.
[2].Lee, T.C.; Lin, S.H.; “a model of space diversity for microwave radio against thermal noise caused outage during multipath fading” Global Telecommunications Conference, 1988, and Exhibition. ''Communications for the Information Age. '' Conference Record, GLOBECOM ''88, IEEE 28 Nov.-1 Dec.1988 Page(s):1440 -1446 vol.3.
[3].Elsabbagh, A.; Abou Chahine, S.; Kheirallah, H.N.,” Microwave propagation on line of sight oversea path in Lebanon”, Radio Science Conference, 2002. (NRSC 2002). Proceedings of the Nineteenth National 19-21 March 2002 Page(s):575 – 582.
[4].Thelaner, L.G. and Knight, W.P., “A study of frequency selective multipath fading on an 8-GHz, 135.6-km overwater digital microwave path”, Military Communications Conference, 1990. MILCOM ''90, Conference Record, ''A New Era''. 1990 IEEE, 30 Sept.-3 Oct. 1990 Page(s):461 - 465 vol.1
[5].Andrew L. Martin, “VHF and Microwave Propagation Characteristics of Ducts”, VK3KAQ V3.5 January 17, 2007.
[6].Arvids Vigants, “Space-Diversity Performance as a Function of Antenna Separation”, Communication Technology, IEEE Transactions on Volume 16, Issue 6, December 1968 Page(s):831 – 836.
[7].R.F.White, “Engineering considerations for microwave communications systems” Electric Co., Inc. GTE-Lenkurt, June, 1970.
[8].David R. Smith, “Digital Transmission Systems”1985 by Wadsworth, Inc.
[9].Abdulkarim Elsabbagh, S. Abou Chahine, H. N. Kheirallah, “Microwave propagation on line of sight oversea path in Lebanon” Radio Science Conference, 2002. (NRSC 2002). Proceedings of the Nineteenth National, 19-21 March 2002 Page(s):575 - 582.
[10].Hitney, H.V.; Richter, J.H.; Pappert, R.A.; Anderson, K.D.; Baumgartner, G.B., Jr.; “Tropospheric Radio Propagation Assessment” Proceedings of the IEEE Volume 73, Issue 2, Feb. 1985 Page(s):265 – 283.
[11].“Propagation data and prediction methods required for the design of terrestrial line-of-sight systems” Rec. ITU-R P.530-12.
[12].“Attenuation by atmospheric gases” Rec. ITU-R P.676-7
[13].“Effects of multipath propagation on design and operation of line-of-sight digital FWSs” Rec. ITU-R F.1093-2
[14].“The radio refractive index” Rec. ITU-R P.453-9
[16].T.C.Lee and S.H.Lin; “A model of space diversity for microwave radio against thermal noise caused outage during multipath fading” Global Telecommunications Conference, 1988, and Exhibition. ''Communications for the Information Age.'' Conference Record, GLOBECOM ''88, IEEE 28 Nov.-1 Dec. 1988 Page(s):1440 - 1446 vol.3.
[17].Makino, H.; Morita, K.; “design of space diversity receiving and transmitting systems for line-of-sight microwave links” Communication Technology, IEEE Transactions on Volume 15, Issue 4, August 1967 Page(s):603 – 614.
[18].Farrow, J.; Skerjanec, R.; “Received Signal Level Measurements on a 160 km Line-of-Sight Radio Link” Communications, IEEE Transactions on Volume 30, Issue 8, August 1982 Page(s):1963 – 1968.
[19].Inoue, T.; Akiyama, T.; “Propagation characteristics on line-of-sight over-sea paths in Japan” Antennas and Propagation, IEEE Transactions on Volume 22, Issue 4, July 1974 Page(s):557 – 565.
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