A study of satellite channel utilization in the presence of rain attenuation in Florida

Abstract

Rain attenuation is the most dominant cause of signal degradation in satellite links operating at Ka-band. This is a particularly serious issue for ground terminal stations located in a sub-tropical region such as state of Florida. Presently, most rain compensation algorithms are based on the use of a fued, large fade margin to combat occasional deep fades. However, the use of a fmed margin, especially for a rainy region, results in an inefficient use of channel capacity for a high percentage of the time. This paper uses an adaptive rain fade counter-measure based on the effective utilization of the channel capacity for several Florida locations with links operating in the Ka-band. In order to determine the outage rates both in terms of channel capacity and BER, Manning's rain attenuation prediction model, based on the rain history of the transmitting and receiving stations has been employed. L INTRODUCTIONSatellite communications form an essential part of global telecommunication systems, carrying large amounts of data, voice and video, and offer a number of features not readily available with other means of coxnmunications. As demand for telecommunication services increases, spectrum congestion forces system planners to use higher frequencies [ 13. Currently, most satelhte W operate at C-band, but as time passes, there wdl be increased use of earth-space links operating at Ka-band.The Advanced Comunications Technology Satellite (ACTS), which was launched into orbit on September 12, 1993, has several experiments on board related to the utdization of earth-space link at Ka-band with downlink hquencies i?om 19.2 to 20.2 GHz and uplink hquencies from 29.1 to 30.0 Ghz [2]. The ACTS mobile terminal program will explore the potentials of Ka-band to meet the needs of future mobile satelhte services. The Kaband, with the promise of less congestion, may also offer increased bandwidth and, therefore, the expansion of system capacity and user services. Also, accompanying sigdicantly smaller ground terminal equipment is expected to reduce system cost [3]. However, one of the major concems of the investigators is that satellite channels at Ka-band are subject to severe performance degradations due to propagation effects that occur at this fadmg region. For a mobile satellite link, the attenuation factors involved include scintillation, shadowing, multipath fading, and the most dominant factor of all, rain attenuation. In the design of such a link maintaining a fixed, large fade margin to combat occasional deep rain fades as done in most rain compensation algorithms, results in severe reduction in communication capacity [4]. Traditional fade countermeasures concentrate on the use of power, bandwidth, and site diversity but pay very little attention to the optimum use of channel capacity. In this paper we use the adaptive rain fade counter measure, based on the effective utllization of the channel capacity proposed in [4] to study the performance of typical ACTS communication links for ground terrmnal locations in Florida. IL ...

Rain Attenuation in Broadband Satellite

“…Therefore, the overall long-term distribution PDF of rain attenuation along the link has the term [10] ( )…”