A new model for predicting fade duration statistics has been developed using a large database compiled for this purpose. Two lognormal functions have been used to model the short and long fade durations due to scintillation and rain events, respectively. The performance of the new model has been compared with existing prediction models such as the ITU-R, COST 205 and Dissanayake-Haidara (D-H). The test results show that the new model has the best performance at Ku, Ka, and Q/V frequency bands. In addition, when results for all the data available are considered, the new model gives the best prediction on average, followed by the D-H, COST 205 and the ITU-R models, respectively.
Propagation effects such as rain or clouds attenuation cause deeper fades in the Ka-band than at lower frequencies.In this collaborative paper, the main results of four long-term Ka-band propagation campaigns are presented. The experiments are carried out in Ottawa, Canada; Aveiro, Portugal; Madrid, Spain; and Toulouse, France. Attenuation statistics are derived from satellite beacon data collected over 6 years at Aveiro, 5 years at Ottawa and Madrid and 2 years at Toulouse. Multi-year measurements allow the production of more stable statistics reflecting the long-term behavior of propagation phenomena and to investigate its year-to-year variability. The beacon signal data was monitored and collected on a continuous basis over the whole measurement period. After a brief introduction of the experiments, rain rate and excess attenuation results are discussed, first for a common measurement period and later for the whole database available. Seasonal attenuation statistics for Ottawa and Aveiro are compared. Finally, fade duration and fade slope statistics derived at three locations are presented and discussed.
Anik F2 is a telecommunications satellite launched in July 2004 for Telesat Canada. It is equipped with a beacon at 20 GHz which supports antenna pointing and user terminal rain mitigation techniques. A receiver was built in 2005 at the Communications Research Centre Canada (CRC) in Ottawa to monitor the Anik F2 beacon signal. Software to perform the data acquisition and process the propagation data collected at CRC was developed as well. One important purpose of the on-going experiment is to investigate fading characteristics relevant to the design of fade mitigation techniques on satellite communication links. The paper describes the main characteristics of the experiment and presents results derived from data collected from the Anik F2 beacon signal at CRC over the period 2006-2007, namely statistics of rain rate, atmospheric-induced attenuation, duration of fades, and fade slope.
Characteristics of rain-induced attenuation at -band measured over a four-year period (1994-1997) with the advanced communications technology satellite (ACTS), Vancouver, BC, Canada, are reported. Event-based analyses of fading are performed and examples of the instantaneous 30/20-GHz frequency-scaling ratio are presented. Long-term cumulative statistics of rain rate as derived from rain-gauge measurements, along with annual attenuation statistics at 20 and 30 GHz, are provided. Finally, attenuation statistics are compared with the ITU-R model and aspects related to local climatic characteristics are considered, aiming to improve the predictions of attenuation due to rain.
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