Comparison of Microwave Links Prediction Methods: Barnett-Vigants vs. ITU Models

Hydro-Quebec operates one of the widest electricity networks in the world. The microwave network infrastructure is essential to manage the power grid in Quebec and therefore, it is important to meet the reliability criteria that are generally above those accepted by traditional communication operators. In addition, over one third of the existing links has lengths between 70km and 90km and operates in extreme weather conditions and all year long. To address these constraints, the microwave links design needs to be as much accurate as possible. The aim of the research presented in this paper is to make a comparative study between two commonly used prediction models for microwave links: Barnett-Vigants and ITU-R P. 530. The flrst part of this work considers each of the following aspects (unavailability, diversity gain and conversion methods). We analyse each aspect as a function of frequency, fading margin and link length. The two models led to signiflcantly difierent results for the unavailability due to multipath as a function of the link length, and also for the space diversity as a function of the gain difierence between the main antenna and the diversity antenna. Remarkable difierences between the two models were also observed when studying the unavailability due to rain as a function of the frequency. The second part of this work compares the overall performance of both models in terms of the total outage probability over ten links with difierent lengths and difierent locations. The difierences observed for some links are signiflcant. The microwave links deployment, like any other wireless network, requires accurate prediction meth- ods in order to minimize the discrepancies between simulation results and real system performance. Although numerous microwave links are deployed around the world, most of them can be considered as short-range or mean-range links for which the path length is less than 20km. Hydro-Quebec operates one of the widest electricity networks in the world. The microwave network infrastructure is essential to manage the power grid in Quebec and therefore, it is important to meet the relia- bility criteria that are generally above those accepted by traditional communication operators. In addition, over one third of the existing links has lengths between 70km and 90km and operates in extreme weather conditions and all year long. To address these constraints, the microwave links design needs to be as much accurate as possible. The aim of the research presented in this paper is to make a comparative study between two commonly used prediction models for microwave links: Barnett-Vigants (B-V) and ITU-R P. 530 (1). This paper is divided in two parts. The flrst part analyses some main aspects (such as unavail- ability, diversity methods and conversion methods) as a function of various parameters, frequency, fading margin and link length. The second part compares the overall performance of both models in terms of the total outage probability over some typical links. Due to space limitation and to reduce the number of flgures, we will present only some flgures which illustrated signiflcant difierences between B-V model and ITU model.