Tomaz Javornik | Jožef Stefan Institute (original) (raw)
Papers by Tomaz Javornik
IEEE Antennas and Wireless Propagation Letters
To enable throughput rates in the terabit-per-second range, future satellite communications will ... more To enable throughput rates in the terabit-per-second range, future satellite communications will have to utilize a large amount of available bandwidth in the Q-band and above. At these high frequencies, the signal is severely degraded and attenuated by tropospheric phenomena, especially rainfall, which reduces the availability of satellite communication links and degrades the quality of service. Site diversity is an efficient technique used to mitigate rain attenuation. In this letter, we evaluate the performance of the large-scale site diversity system consisting of ground stations in Ljubljana and Budapest based on long-term satellite signal measurement campaigns by Alphasat at 39.402 GHz. The measured attenuation time series are statistically analyzed and presented for a period of one year and compared with three representative prediction models.
12th European Conference on Antennas and Propagation (EuCAP 2018)
2017 11th European Conference on Antennas and Propagation (EUCAP), 2017
In this paper, the impact of truck convoys on radio wave propagation at the mm-wave frequency ban... more In this paper, the impact of truck convoys on radio wave propagation at the mm-wave frequency band in a two lane road tunnel is analyses by computer simulations. The analyzes reveal that the propagation of radio waves is not affected outside the convoy if a convoy occupies only one lane, while two convoys in both lanes cause serious drop of signal level behind the convoys. The signal level is decreased and delay spread is increased within the convoy, which suggests the usage of the vehicle to vehicle communication within a convoy. In addition, due to misalignment of transmitting and receive directional antennas a significant signal gap is occurred close to the base station. We suggest the usage of two antennas at the base station, one omnidirectional to cover proximity areas and the second one directional to cover distance areas along the tunnel.
2020 8th International Conference on Wireless Networks and Mobile Communications (WINCOM), 2020
The main purpose of this paper is to analyze the impact of cooperative multi-input-multi-output (... more The main purpose of this paper is to analyze the impact of cooperative multi-input-multi-output (CO-MIMO) on system capacity and coverage in hilly environment and thus to extend the current knowledge on CO-MIMO gains in the rural alpine regions. The radio wave propagation in the considered region was simulated for three different approaches: frequency reuse 3, frequency reuse 1 and cooperative approach. Based on the simulation results the received signal levels per base station (BS) were calculated, as well as the signal to interference noise ratio (SINR) and capacity maps, cumulative probability density function of map-bin SINR and map-bin capacity for each approach, presented as the percentage of area that exceeds the capacity and SINR. These are used for comparison of the three approaches with respect to system capacity and signal coverage respectively. The results reveal the advantages of CO-MIMO in hilly rural environments and thus we recommend the CO-MIM O approach application in rural hilly areas.
2019 23rd International Conference on Applied Electromagnetics and Communications (ICECOM), 2019
In this paper a novel idea of estimating the 3D geometry and building material of indoor environm... more In this paper a novel idea of estimating the 3D geometry and building material of indoor environments is proposed. The idea is based on assumption that the received radio signal is distorted due to interaction with the surrounding objects and thus includes the signature of the radio environment. We describe the methodology how to apply radio environment signatures for characterization of geometry and building material of indoor environments applying machine learning tools using ray tracing simulations and ultra-wide band communication technology. The idea is based on the assumption that the emerging broadband wireless systems applies multiple antenna and is able to estimate the channel impulse response for each transmit-receive antenna pair.
In this paper we give a thorough study of radio propagation models suitable for smart city applic... more In this paper we give a thorough study of radio propagation models suitable for smart city applications and select two channel models for coverage prediction of wireless sensor networks for two typical propagation environments often occurs in smart city applications, namely the open area plane earth model for open areas and the four slope channel model for street canyons and tunnels. The measurement campaigns performed at three carrier frequencies applied for wireless sensor networks in Europe i.e. 400 MHz, 868 MHz and 2.4 GHz, reveals, that in open areas the plane earth model fits the measurements better than two slope model and four slope channel model gives sufficiently high accurate path loss prediction in tunnels and street corridors. Keywords— four slope model, GRASS RaPlaT, path loss, plane earth model, RSSI measurements, TETRA, two slope model, wireless sensor networks, WSN testbed.
Radio propagation simulation tools are important for prediction and verification of the radio sig... more Radio propagation simulation tools are important for prediction and verification of the radio signal coverage by individual transmitters or transmitter networks such as mobile phone cellular networks. In the case of a large geographic area with a relative high resolution, the simulation can become computationally demanding, taking a considerable amount of time to accomplish. Parallel processing can be used to speed up the computation and shorten the response time. We used the GPGPU (General-Purpose Computing on Graphics Processing Units) approach for the open source GRASS-RaPlaT radio propagation tool. By using OpenCL, we modified the existing radio propagation model modules for GPU (Graphics Processing Unit) execution, achieving multiple times processing speedup for computationally intensive modules. In the article, we present our GPU parallelization approach and analyze the results and conditions that must be fulfilled to successfully employ GPU computation and achieve a considera...
2019 23rd International Conference on Applied Electromagnetics and Communications (ICECOM), 2019
Ageing of population will increase the number of people demanding the assistance and medical supp... more Ageing of population will increase the number of people demanding the assistance and medical support. In order to increase the life quality of elderly people the medical support and assistance will be provided at people homes which require the development of new technologies to support their living and reduce needed interaction of the nursing stuff. Activity detection and deviation from daily activity patterns are recognized as the main indicators to identify modification of the people behaviour showing potential risk in the deterioration of their physical and mental health. The passive and active localization are two key technologies applied for activity detection and tracking. In this respect in this paper we specify a new communication protocol for passive and active localization applicable for assisted living applications supporting tracking one person in their apartment. Communication protocol exploits the IEEE 802.15.4-2011 UWB communication technology for ranging and channel ...
Electronics, 2021
Available digital maps of indoor environments are limited to a description of the geometrical env... more Available digital maps of indoor environments are limited to a description of the geometrical environment, despite there being an urgent need for more accurate information, particularly data about the electromagnetic (EM) properties of the materials used for walls. Such data would enable new possibilities in the design and optimization of wireless networks and the development of new radio services. In this paper, we introduce, formalize, and evaluate a framework for machine learning (ML) based wireless sensing of indoor surface materials in the form of EM properties. We apply the radio-environment (RE) signatures of the wireless link, which inherently contains environmental information due to the interaction of the radio waves with the environment. We specify the content of the RE signature suitable for surface-material classification as a set of multipath components given by the received power, delay, phase shift, and angle of arrival. The proposed framework applies an ML approach ...
2020 European Conference on Networks and Communications (EuCNC), 2020
Localization of people and assets is increasingly important contextual information for many appli... more Localization of people and assets is increasingly important contextual information for many application areas. In the paper we present a new self-calibrated Ultra-Wide Band (UWB) device free localization (DFL) and activity detection approach. The approach applies automatic "zero touch" system setup applying multidimensional scaling (MDS) algorithm for node self-location and local coordinate system specification. The node-to-node distance estimation is based on a two-way ranging method. The radio tomography imaging (RTI) is applied to estimate the location of a person. The study investigates the sensitivity of the system on the number of nodes. It reveals that in order to achieve the expected location error in a system with a low number of nodes, the signal level measurements in the RTI approach have to be complemented by channel property measurements such as channel impulse response captured by UWB system.
Sensors, 2021
The LOG-a-TEC testbed is a combined outdoor and indoor heterogeneous wireless testbed for experim... more The LOG-a-TEC testbed is a combined outdoor and indoor heterogeneous wireless testbed for experimentation with sensor networks and machine-type communications, which is included within the Fed4FIRE+ federation. It supports continuous deployment principles; however, it is missing an option to monitor and control the experiment in real-time, which is required for experiment execution under comparable conditions. The paper describes the implementation of the experiment control and monitoring system (EC and MS) as the upgrade of the LOG-a-TEC testbed. EC and MS is implemented within existing infrastructure management and built systems as a new service. The EC and MS is accessible as a new tab in sensor management system portal. It supports several commands, including start, stop and restart application, exit the experiment, flash or reset the target device, and displays the real-time status of the experiment application. When nodes apply Contiki-NG as their operating system, the Contiki...
Path loss models are widely used in wireless network planning, mainly during an initial deploymen... more Path loss models are widely used in wireless network planning, mainly during an initial deployment. Empirical path loss models are frequently used because of their simplicity and limited reliance on a detailed terrain data knowledge. The appropriateness of different path loss models for broadband wireless access (BWA) network planning has not been properly evaluated by commercially deployed systems so far. One of the potential promising candidates is the Erceg path loss model, which was evaluated with extensive field measurements taken in the city of Ljubljana. Results show that the model is rather successful in the path loss prediction for a typical suburban area of the city while for the urban environment it should be modified.
This paper presents the applicability of commercial and license free simulation tools for path lo... more This paper presents the applicability of commercial and license free simulation tools for path loss calculations in tunnels and underground corridors. WinProp simulation tool has been selected for path loss calculation based on deep study of simulation tools performance, implemented radio propagation algorithms, results representation and representation and modeling of the propagation environment. A set of simulations at various frequencies were performed for tunnels with standard cross-sectional shapes, dimensions, material properties and in addition with presence of the obstacles preventing radio wave propagation along tunnel. The signal frequency and dimension of the tunnel cross section have considerable impact on path loss, while the tunnel cross shape and the transmitter/receiver position does not have it. The results were evaluated by four-slope empirical path loss model and measurement results performed in two different tunnels. The comparison confirmed the adequacy of the s...
International Journal of Communication
Radio signal propagation prediction plays an essential role in planning of modern broadband mobil... more Radio signal propagation prediction plays an essential role in planning of modern broadband mobile radio networks. While the less accurate statistical models predict only the path loss, the more precise ray tracing techniques enable computation of additional parameters, e.g. the mean delay and the delay spread, which are significant for the 4G network planning. The existing ray tracing methods are mainly applied in the indoor and narrow urban environments. In this paper, an open-source solution for propagation prediction with a ray tracing method in the open urban and rural areas is presented. The emphasis is on the implementation of a computationally efficient procedure, which is divided in to two separately optimized problems, tessellation and ray tracing. Ray tracing is implemented by applying an improved shooting and bouncing ray (SBR) approach. The efficiency of the implementation is analysed in terms of computational complexity and results accuracy. The simulation results show...
WSEAS Transactions on Communications
The cellular concept applied in mobile communication systems enables significant increase of over... more The cellular concept applied in mobile communication systems enables significant increase of overall system capacity, but requires careful radio network planning and dimensioning. Wireless and mobile network operators typically rely on various commercial radio network planning and dimensioning tools, which incorporate different radio signal propagation models. In this paper we present the use of open-source Geographical Resources Analysis Support System (GRASS) for the calculation of radio signal coverage. We developed GRASS modules for radio coverage prediction for a number of different radio channel models, with antenna radiation patterns given in the standard MSI format. The results are stored in a data base (e.g. MySQL, PostgreSQL) for further processing and in a simplified form as a bit-map file for displaying in GRASS. The accuracy of prediction was confirmed by comparison with results obtained by a dedicated professional prediction tool as well as with measurement results.
2006 International Workshop on Satellite and Space Communications, 2006
Abstract High altitude platform (HAP) system offers establishment of communication links with pre... more Abstract High altitude platform (HAP) system offers establishment of communication links with predominantly line-of-sight (LOS) conditions due to high elevation angles. However, in mobile scenario, the transmitted signal is still subject to blocking due to obstacles between ...
2014 1st International Workshop on Cognitive Cellular Systems (CCS), 2014
In this paper we propose radio environment map (REM) as a mean for setting up and maintaining wir... more In this paper we propose radio environment map (REM) as a mean for setting up and maintaining wireless communications in disaster areas providing services to public protection disaster relief (PPDR) forces and disaster victims. The wireless communication infrastructure is expected to be partially or fully damaged in the disaster area, resulting in an unknown radio environment. In our approach, the initial base station parameters are estimated by applying the knowledge of the radio environment prior to the disaster and by an initial spectrum sensing, while during the operation phase the base station parameters are updated based on the REM, which relies on distributed spectrum sensing. The REM implementation using the open source geographical information system GRASS and its add-on RaPlaT is described.
2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2013
ABSTRACT The design of opportunistic wireless networks for disaster relief operations requires a ... more ABSTRACT The design of opportunistic wireless networks for disaster relief operations requires a good understanding of communication demands and technological capabilities. Theoretically determined or simulation based parameters such as data rate and communication range need to be experimentally confirmed in practice, requiring measurement campaigns in realistic environment. This paper reports the results from three experiments, performed with a hot-air balloon and a personal car, equipped with TETRA, WiFi and WiMAX communication equipment. The results for signal measurements show the strengths and weaknesses of the three technologies used for low altitude platform communications and reveal some practical aspects, which are important for the network designers and operators.
IEEE Antennas and Wireless Propagation Letters
To enable throughput rates in the terabit-per-second range, future satellite communications will ... more To enable throughput rates in the terabit-per-second range, future satellite communications will have to utilize a large amount of available bandwidth in the Q-band and above. At these high frequencies, the signal is severely degraded and attenuated by tropospheric phenomena, especially rainfall, which reduces the availability of satellite communication links and degrades the quality of service. Site diversity is an efficient technique used to mitigate rain attenuation. In this letter, we evaluate the performance of the large-scale site diversity system consisting of ground stations in Ljubljana and Budapest based on long-term satellite signal measurement campaigns by Alphasat at 39.402 GHz. The measured attenuation time series are statistically analyzed and presented for a period of one year and compared with three representative prediction models.
12th European Conference on Antennas and Propagation (EuCAP 2018)
2017 11th European Conference on Antennas and Propagation (EUCAP), 2017
In this paper, the impact of truck convoys on radio wave propagation at the mm-wave frequency ban... more In this paper, the impact of truck convoys on radio wave propagation at the mm-wave frequency band in a two lane road tunnel is analyses by computer simulations. The analyzes reveal that the propagation of radio waves is not affected outside the convoy if a convoy occupies only one lane, while two convoys in both lanes cause serious drop of signal level behind the convoys. The signal level is decreased and delay spread is increased within the convoy, which suggests the usage of the vehicle to vehicle communication within a convoy. In addition, due to misalignment of transmitting and receive directional antennas a significant signal gap is occurred close to the base station. We suggest the usage of two antennas at the base station, one omnidirectional to cover proximity areas and the second one directional to cover distance areas along the tunnel.
2020 8th International Conference on Wireless Networks and Mobile Communications (WINCOM), 2020
The main purpose of this paper is to analyze the impact of cooperative multi-input-multi-output (... more The main purpose of this paper is to analyze the impact of cooperative multi-input-multi-output (CO-MIMO) on system capacity and coverage in hilly environment and thus to extend the current knowledge on CO-MIMO gains in the rural alpine regions. The radio wave propagation in the considered region was simulated for three different approaches: frequency reuse 3, frequency reuse 1 and cooperative approach. Based on the simulation results the received signal levels per base station (BS) were calculated, as well as the signal to interference noise ratio (SINR) and capacity maps, cumulative probability density function of map-bin SINR and map-bin capacity for each approach, presented as the percentage of area that exceeds the capacity and SINR. These are used for comparison of the three approaches with respect to system capacity and signal coverage respectively. The results reveal the advantages of CO-MIMO in hilly rural environments and thus we recommend the CO-MIM O approach application in rural hilly areas.
2019 23rd International Conference on Applied Electromagnetics and Communications (ICECOM), 2019
In this paper a novel idea of estimating the 3D geometry and building material of indoor environm... more In this paper a novel idea of estimating the 3D geometry and building material of indoor environments is proposed. The idea is based on assumption that the received radio signal is distorted due to interaction with the surrounding objects and thus includes the signature of the radio environment. We describe the methodology how to apply radio environment signatures for characterization of geometry and building material of indoor environments applying machine learning tools using ray tracing simulations and ultra-wide band communication technology. The idea is based on the assumption that the emerging broadband wireless systems applies multiple antenna and is able to estimate the channel impulse response for each transmit-receive antenna pair.
In this paper we give a thorough study of radio propagation models suitable for smart city applic... more In this paper we give a thorough study of radio propagation models suitable for smart city applications and select two channel models for coverage prediction of wireless sensor networks for two typical propagation environments often occurs in smart city applications, namely the open area plane earth model for open areas and the four slope channel model for street canyons and tunnels. The measurement campaigns performed at three carrier frequencies applied for wireless sensor networks in Europe i.e. 400 MHz, 868 MHz and 2.4 GHz, reveals, that in open areas the plane earth model fits the measurements better than two slope model and four slope channel model gives sufficiently high accurate path loss prediction in tunnels and street corridors. Keywords— four slope model, GRASS RaPlaT, path loss, plane earth model, RSSI measurements, TETRA, two slope model, wireless sensor networks, WSN testbed.
Radio propagation simulation tools are important for prediction and verification of the radio sig... more Radio propagation simulation tools are important for prediction and verification of the radio signal coverage by individual transmitters or transmitter networks such as mobile phone cellular networks. In the case of a large geographic area with a relative high resolution, the simulation can become computationally demanding, taking a considerable amount of time to accomplish. Parallel processing can be used to speed up the computation and shorten the response time. We used the GPGPU (General-Purpose Computing on Graphics Processing Units) approach for the open source GRASS-RaPlaT radio propagation tool. By using OpenCL, we modified the existing radio propagation model modules for GPU (Graphics Processing Unit) execution, achieving multiple times processing speedup for computationally intensive modules. In the article, we present our GPU parallelization approach and analyze the results and conditions that must be fulfilled to successfully employ GPU computation and achieve a considera...
2019 23rd International Conference on Applied Electromagnetics and Communications (ICECOM), 2019
Ageing of population will increase the number of people demanding the assistance and medical supp... more Ageing of population will increase the number of people demanding the assistance and medical support. In order to increase the life quality of elderly people the medical support and assistance will be provided at people homes which require the development of new technologies to support their living and reduce needed interaction of the nursing stuff. Activity detection and deviation from daily activity patterns are recognized as the main indicators to identify modification of the people behaviour showing potential risk in the deterioration of their physical and mental health. The passive and active localization are two key technologies applied for activity detection and tracking. In this respect in this paper we specify a new communication protocol for passive and active localization applicable for assisted living applications supporting tracking one person in their apartment. Communication protocol exploits the IEEE 802.15.4-2011 UWB communication technology for ranging and channel ...
Electronics, 2021
Available digital maps of indoor environments are limited to a description of the geometrical env... more Available digital maps of indoor environments are limited to a description of the geometrical environment, despite there being an urgent need for more accurate information, particularly data about the electromagnetic (EM) properties of the materials used for walls. Such data would enable new possibilities in the design and optimization of wireless networks and the development of new radio services. In this paper, we introduce, formalize, and evaluate a framework for machine learning (ML) based wireless sensing of indoor surface materials in the form of EM properties. We apply the radio-environment (RE) signatures of the wireless link, which inherently contains environmental information due to the interaction of the radio waves with the environment. We specify the content of the RE signature suitable for surface-material classification as a set of multipath components given by the received power, delay, phase shift, and angle of arrival. The proposed framework applies an ML approach ...
2020 European Conference on Networks and Communications (EuCNC), 2020
Localization of people and assets is increasingly important contextual information for many appli... more Localization of people and assets is increasingly important contextual information for many application areas. In the paper we present a new self-calibrated Ultra-Wide Band (UWB) device free localization (DFL) and activity detection approach. The approach applies automatic "zero touch" system setup applying multidimensional scaling (MDS) algorithm for node self-location and local coordinate system specification. The node-to-node distance estimation is based on a two-way ranging method. The radio tomography imaging (RTI) is applied to estimate the location of a person. The study investigates the sensitivity of the system on the number of nodes. It reveals that in order to achieve the expected location error in a system with a low number of nodes, the signal level measurements in the RTI approach have to be complemented by channel property measurements such as channel impulse response captured by UWB system.
Sensors, 2021
The LOG-a-TEC testbed is a combined outdoor and indoor heterogeneous wireless testbed for experim... more The LOG-a-TEC testbed is a combined outdoor and indoor heterogeneous wireless testbed for experimentation with sensor networks and machine-type communications, which is included within the Fed4FIRE+ federation. It supports continuous deployment principles; however, it is missing an option to monitor and control the experiment in real-time, which is required for experiment execution under comparable conditions. The paper describes the implementation of the experiment control and monitoring system (EC and MS) as the upgrade of the LOG-a-TEC testbed. EC and MS is implemented within existing infrastructure management and built systems as a new service. The EC and MS is accessible as a new tab in sensor management system portal. It supports several commands, including start, stop and restart application, exit the experiment, flash or reset the target device, and displays the real-time status of the experiment application. When nodes apply Contiki-NG as their operating system, the Contiki...
Path loss models are widely used in wireless network planning, mainly during an initial deploymen... more Path loss models are widely used in wireless network planning, mainly during an initial deployment. Empirical path loss models are frequently used because of their simplicity and limited reliance on a detailed terrain data knowledge. The appropriateness of different path loss models for broadband wireless access (BWA) network planning has not been properly evaluated by commercially deployed systems so far. One of the potential promising candidates is the Erceg path loss model, which was evaluated with extensive field measurements taken in the city of Ljubljana. Results show that the model is rather successful in the path loss prediction for a typical suburban area of the city while for the urban environment it should be modified.
This paper presents the applicability of commercial and license free simulation tools for path lo... more This paper presents the applicability of commercial and license free simulation tools for path loss calculations in tunnels and underground corridors. WinProp simulation tool has been selected for path loss calculation based on deep study of simulation tools performance, implemented radio propagation algorithms, results representation and representation and modeling of the propagation environment. A set of simulations at various frequencies were performed for tunnels with standard cross-sectional shapes, dimensions, material properties and in addition with presence of the obstacles preventing radio wave propagation along tunnel. The signal frequency and dimension of the tunnel cross section have considerable impact on path loss, while the tunnel cross shape and the transmitter/receiver position does not have it. The results were evaluated by four-slope empirical path loss model and measurement results performed in two different tunnels. The comparison confirmed the adequacy of the s...
International Journal of Communication
Radio signal propagation prediction plays an essential role in planning of modern broadband mobil... more Radio signal propagation prediction plays an essential role in planning of modern broadband mobile radio networks. While the less accurate statistical models predict only the path loss, the more precise ray tracing techniques enable computation of additional parameters, e.g. the mean delay and the delay spread, which are significant for the 4G network planning. The existing ray tracing methods are mainly applied in the indoor and narrow urban environments. In this paper, an open-source solution for propagation prediction with a ray tracing method in the open urban and rural areas is presented. The emphasis is on the implementation of a computationally efficient procedure, which is divided in to two separately optimized problems, tessellation and ray tracing. Ray tracing is implemented by applying an improved shooting and bouncing ray (SBR) approach. The efficiency of the implementation is analysed in terms of computational complexity and results accuracy. The simulation results show...
WSEAS Transactions on Communications
The cellular concept applied in mobile communication systems enables significant increase of over... more The cellular concept applied in mobile communication systems enables significant increase of overall system capacity, but requires careful radio network planning and dimensioning. Wireless and mobile network operators typically rely on various commercial radio network planning and dimensioning tools, which incorporate different radio signal propagation models. In this paper we present the use of open-source Geographical Resources Analysis Support System (GRASS) for the calculation of radio signal coverage. We developed GRASS modules for radio coverage prediction for a number of different radio channel models, with antenna radiation patterns given in the standard MSI format. The results are stored in a data base (e.g. MySQL, PostgreSQL) for further processing and in a simplified form as a bit-map file for displaying in GRASS. The accuracy of prediction was confirmed by comparison with results obtained by a dedicated professional prediction tool as well as with measurement results.
2006 International Workshop on Satellite and Space Communications, 2006
Abstract High altitude platform (HAP) system offers establishment of communication links with pre... more Abstract High altitude platform (HAP) system offers establishment of communication links with predominantly line-of-sight (LOS) conditions due to high elevation angles. However, in mobile scenario, the transmitted signal is still subject to blocking due to obstacles between ...
2014 1st International Workshop on Cognitive Cellular Systems (CCS), 2014
In this paper we propose radio environment map (REM) as a mean for setting up and maintaining wir... more In this paper we propose radio environment map (REM) as a mean for setting up and maintaining wireless communications in disaster areas providing services to public protection disaster relief (PPDR) forces and disaster victims. The wireless communication infrastructure is expected to be partially or fully damaged in the disaster area, resulting in an unknown radio environment. In our approach, the initial base station parameters are estimated by applying the knowledge of the radio environment prior to the disaster and by an initial spectrum sensing, while during the operation phase the base station parameters are updated based on the REM, which relies on distributed spectrum sensing. The REM implementation using the open source geographical information system GRASS and its add-on RaPlaT is described.
2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2013
ABSTRACT The design of opportunistic wireless networks for disaster relief operations requires a ... more ABSTRACT The design of opportunistic wireless networks for disaster relief operations requires a good understanding of communication demands and technological capabilities. Theoretically determined or simulation based parameters such as data rate and communication range need to be experimentally confirmed in practice, requiring measurement campaigns in realistic environment. This paper reports the results from three experiments, performed with a hot-air balloon and a personal car, equipped with TETRA, WiFi and WiMAX communication equipment. The results for signal measurements show the strengths and weaknesses of the three technologies used for low altitude platform communications and reveal some practical aspects, which are important for the network designers and operators.