Assessments of Time Diversity Rain Fade Mitigation Technique for V-band Space-Earth Link Operating in Tropical Climate

Abstract

Satellite communication systems are moving towards greater capacity. Millimeter wave frequency offers a large bandwidth allocation, requires small antenna size and should not experience congested spectrum environment. Nonetheless, rain posses a grave threat to such satellite communication links especially in tropical region where the hydrometeors can severely affect the signal. Rain is the factor that typically limits the implementation or use of higher frequencies for satellite communications in this region. Time diversity is a promising mitigation technique to countermeasure such impairments. It is envisioned that the technique will not be requiring extensive auxiliary's equipment. This paper outlines the likely improvement of a future V-band frequency space-Earth link using proposed time diversity (TD) technique. The analyses relating to the performance prediction of a projected satellite communication link in a tropical climate environment assimilating TD scheme are also included. The recovery strategy and its associated equations were deduced reflecting the likely memory capacity requirement of TD. The knowledge will be incorporated accordingly at the receiver with hopes to mitigate attenuation due to rain endured by the propagation path.  Index Terms-satellite communications, fade mitigation techniques, time diversity, and millimeter wave I. INTRODUCTION Since 1965, the reaches and capabilities of satellite communications grow intensively in terms of usages and offered services. At the first preface, satellite communications was used to provide telephony services. The trend of the services provided by satellite then diversifies into the area of broadcasting services. It gradually expanded to TV broadcast distribution, directto-home (DTH), internet trunking, broadband access and fixed satellite services (FSS). HDTV and video-ondemand (VOD), are two of the examples of the current Manuscript

Probability distributions of rain attenuation obtainable with linear combining techniques in space‐to‐Earth links using time diversity

“…Its efficacy is based on the experimental evidence that rain attenuation decorrelates after few minutes at large fades, and after few tens of minutes at small fades, so that, by transmitting twice (or more times) the same signal with a suitable fixed time delay of the order of several minutes, the receiver can select the best signal and reduce link outage. This description suits the analysis that propagation experts conducted in the past and known, in the theory of diversity systems, as selection diversity. Only recently linear combining techniques have been applied to time diversity system …”

“…First proposed by Fukuchi, time diversity is a long‐studied fade countermeasure to rain attenuation, applicable to satellite communication services that can tolerate long time delay (minutes), such as television and audio broadcasting, data transfer from geostationary satellites . Time diversity can be seen as an evolution of the less‐demanding Automatic Repeat Request (ARQ) techniques, because direct and delayed signals are continuously transmitted with a suitable time delay, while in the classic ARQ techniques, the signal is retransmitted in the same channel 2 or more times until it is correctly received.…”

Prediction of Time Diversity Gain for Earth-to-Satellite Microwave Link Design Based on Real Time Rain Intensity Measurement

“…In [11], it has been demonstrated that rain attenuation via earth-to-satellite link is closely proportional to rain intensity, which attenuation variation occurs throughout the propagation route as a result of rain variation. Previously synthetic storm technique (SST) technique was used [12], [13], [14] to predict rain attenuation time series from measured rain rate time series with and without time delays. However, when compared to measured gain, the technique consistently tends to overestimate gain.…”