Fade Dynamics Investigation applying Statistics of Fade Duration and Level Crossing Rate
Abstract — The impact of rain attenuation on wireless communication signals is predominant because of the used high frequency (above 10 GHz). The knowledge of statistics of attenuation is very important for planning point-to-point microwave links operating in high frequency band. Describing the statistics of attenuation is possible for instance with fade duration or level crossing rate. In our examination we determine these statistics from one year measured data for a given microwave link, and we are going to make an attempt to transform the level crossing rate statistic to fade duration statistic. Keywords — Rain Attenuation Measurement, Fade duration, Level Crossing Rate. I. I NTRODUCTION O investigate wave propagation phenomena a rain attenuation and weather data measurement system was established. Currently in Hungary a number of point-to-point millimetre wave links operating in the frequency bands of 13, 15, 23 and 38 GHz. The received IF signal powers are collected with the meteorological data together using weather stations at different locations for data collection. This paper investigates the dynamics of rain attenuation. Different statistics such as fade duration, number of events and level crossing rate are important for analysis of wave propagation phenomena, because they are indicating important information about the dynamics of the received signal. These statistics can be derived from our available measured data. To prepare these second-order statistics a one year period data measured on one 38 GHz link in Hungary in 2004 is considered. Fade duration and level crossing rate statistics will be compiled for attenuation exceeding different attenuation levels (fade thresholds) from 3 up to 8 dB. The parameters of the investigated link are described in Table I. The paper is organized as follows: Section 2 presents the fade duration and level crossing rate, Section 3 describes our data processing method while Section 4 shows our fade duration estimation from LCR, concluding remarks are given in Section 5.
Statistical analysis of the Syracuse 3 satellite EHF propagation experiment
An Earth-to-satellite propagation experiment operating in the EHF band was set up as part of the Syracuse 3 program. The Syracuse 3 satellites are the new generation of French military SATCOM systems. This experiment is a good opportunity to carry out attenuation measurements and increase knowledge about tropospheric propagation effects on EHF links at a low elevation angle (17°). At these frequencies (20 & 44 GHz), the attenuation due to the troposphere can be very strong. This paper presents yearly statistics of attenuation level, frequency scaling ratio and fade durations. A comparison with ITU models is given.
Short-term frequency scaling of clear-sky and wet amplitude scintillation
For the design of ULPC systems that can compensate for different types of fading, the short-term frequency scaling factor of all types of fading is needed. Attention is focused on the short-term frequency scaling factor of clear-sky amplitude scintillation and amplitude scintillation occurring with rain attenuation simultaneously, often referred to as wet amplitude scintillation. It is shown that these factors are strongly variable: they depend on various meteorological parameters and on the aperture illumination efficiency of the receiving antenna. In addition, it is shown that amplitude scintillation can only be compensated partly by means of ULPC, owing to the limited correlation of amplitude scintillation measured on two radiowaves with different carrier frequencies propagating along the same path simultaneously. Furthermore, a new procedure is presented to separate rain attenuation and amplitude scintillation.