Péter Kántor

Influence of climate variability on performance of wireless microwave links

Microwave telecommunications links that are operating above 10 GHz are significantly affected by precipitation, especially by rain. In order to study the attenuation caused by precipitation a measurement system is operating at BME-HVT. The results of the measurement system can also help to examine the change of the climate, whereas variations in the intensity and frequency of precipitation indicate variations in the characteristics of the propagation of microwaves as well. A nonconstant climate indicates necessary changes in the network planning of microwave telecommunication networks in order to adapt the link performance (i.e. availability, fade margin, etc.) to the forthcoming climate conditions. Moreover, whereas the climate can vary in time and space as well, it is important to have the local trends of the variation available. Our objective is to study the effects of the climate variability and climate change on the availability of the microwave networks by processing the attenuation measurement data of microwave links recorded during the last 14 years within local (Hungarian) conditions. In this paper results of four microwave links established in Budapest are investigated. In order to get a joint statistics of diverse links a transformation was performed on the attenuation data measured on the investigated microwave links. Thereby a local trend in the attenuation and fade duration statistics became available to be investigated, which is specific to Budapest. The results can help to improve the recommendations on microwave network planning and adapt them to the varying climate.

Investigation and simulation of meteorological effects on millimeter wave ad-hoc mesh networks in 5G systems

Substantial growth of mobile data and rapidly increasing spread of smartphones nowadays present major challenge for mobile service providers. The allotted spectrum for the currently operating mobile communicating systems have been saturated in the last years by such considerable rate that the futures fifth generation network would not be able to fulfil its requirements without applying new frequencies. In accordance with the concept of 5G, millimeter wave spectrum will also be used along with the current frequency bands. This spectrum however, introduces meteorological effects as a new and significant attenuation factor. In this paper mm-wave propagation affected by precipitation will be investigated and a simulation environment (written in Matlab) used for the 5G mm-wave mesh networks statistical investigation will be presented.

Diversity investigation of satellite backbone network for BFWA systems

The Broadband Fixed Wireless Access (BFWA) networks are terrestrial systems operating at high carrier frequencies (above 20 GHz), therefore one of the most harmful circumstantial factors in these systems is the attenuation caused by precipitation, especially by rain. Employing site diversity is a well-known method to improve the signal to interference plus noise ratio conditions within the BFWA network. The backbone of a BFWA can be wired or wireless terrestrial, however the connection between base stations and the operators core network can be also established by high frequency satellite links. Applying a satellite backbone system and route diversity between the Earth-space links can compensate precipitation attenuation. In this paper the efficiency of the diversity scheme in a satellite backbone network for BFWA system will be presented.

Comparison of rain attenuation prediction models for terrestrial links and their impact on the performance of link transformation

As rainfall has a serious effect on wireless microwave transmission, performance of rain rate and rain attenuation prediction models are vital for planning of networks consisting of such links. As several different prediction models exist in the literature we give a comparison of the performance of the most applied ones. Moreover, we introduce the transformation of rain attenuation over different microwave links based on the investigated methods. We identify the most suitable rain attenuation prediction model and verify the proposed link transformation model with the ITU-P.530-15 model on long-term statistics. The purpose of this document is to investigate different rain attenuation prediction models for terrestrial links and to find a suitable prediction method to perform a transformation of rain attenuation on microwave links with different physical parameters.

Atmospheric turbulence on FSO at 785 nm

The atmospheric turbulence is one of the cause of channel impairments of the free space optical links. This phenomenon appears even in case of clear sky conditions and according to the literature it may affect the availability of the connection. In this paper the atmospheric turbulence will be studied, based on longterm measurement data. The measurements were performed on a 930m long free space optical link that operates at 785 nm wavelength.

Availability improvement of free-space optical and microwave communications links — A diversity system

Free-space optical (FSO) and microwave telecommunication links have considerably adverse propagation characteristics. For radio waves that are operating in the millimeter wavelength one of the most harmful circumstantial factors is the attenuation caused by precipitation, especially by rain. However, for FSO links the main adverse effect is fog, being most responsible for the unavailability of FSO links. These adverse propagation characteristics allow good efficiency for a site diversity system that consists of parallel FSO and millimeterwave links. In order to study the propagation characteristics of these types of links a measurement system is operating at Budapest University of Technology and Economics, Department of Broadband Infocommunicatons and Electromagnetic Theory (BME-HVT). In this paper the efficiency of a parallel FSO-microwave site diversity system is presented on the basis of the results of the measurement system. The outage probabilities of the FSO and microwave links are compared to the outage probability of the diversity system. Moreover, the possibility of microwave transmitter power reduction is investigated as well in case of the application of the hybrid diversity system.

Adaptive Link Assignment Applied in Case of Video Streaming in a Multilink Environment

Nowadays the importance of multilink networks where end-to-end connections are provided by applying multiple communication links simultaneously is rapidly growing due to the expanding demand for high-speed Internet access and real-time video transmission. Since channel conditions may vary in time and space, the selection of the used communication links depends on traffic load, latency, coverage and desired data rate. Combining multilink architecture and adaptive video transmission can be therefore an effective solution for broadcasting video streams. In this paper the efficiency of the adaptive transmission scheme will be presented for a terrestrial heterogeneous multilink network which consists of WiMAX, LTE and HSDPA communication links.