Spatial Markov model of fade duration on terrestrial radio links

Abstract

This paper introduces a modeling method to express the spatial variations of the propagation channel in a cellular mobile radio system which consists of a backbone node and several millimeter band links forming a star network around the node. The area covered by this system is only a few square kilometers but propagation impairments can be observed if a rain cell moves across this field. One of the characteristics of the channel what can be used by the system design engineers is the fade duration statistics. At first we introduce a Markov-chain based model [4] to calculate the fade duration statistics for the radio links. This model is based on the long-term (one year) measurement of the channel; therefore it is not applicable to show the local variability of the channel if a rain cell is moving over the cover area of the node. A second Markov model of a two dimensional (2D) nonsymmetrical random walk will be introduced to characterize the movement of the rain cell. The dimension of the rainy area and the point rainfall rate will be expressed by the EXCELLmodel[2]. We will show that the local random walk model, the rain rate and attenuation calculations allows us to generate attenuation time series caused by the moving rain cell and express the spatial variations of the fade duration in a start-formed microwave network. (6 pages)