Apostolos Gkamas
Short CV: Apostolos Gkamas obtained his Diploma, Master Degree and Ph.D from the Computer Engineering and Informatics DepartmentOther site of Patras University (Greece)Other site. He is currently Associate Professor in University Ecclesiastical Academy of Vella, IoanninaOther site. His research interests include Computer Networks, Telematics, Multimedia transmission and Cross Layer Design. More particular he is engaged in transmission of multimedia data over networks and multicast congestion control. He has published more than 70 papers in international Journals and well-known refereed conferences. He is also co-author of three books (one with subject Multimedia and Computer Networks one with subject Special Network Issues and one with subject IPv6). He has participated in various R&D project (in both EU and national) such as IST, FP6, FP7, Intereg eLearning, PENED, EPEAEK, Information Society.
Journal Articles
Bouras, Christos; Gkamas, Apostolos; Salgado, Spyridon Aniceto Katsampiris
Long Range Based IoT Search and Rescue System, a Human- Computer Interaction Preliminary Study and Implementation Journal Article
In: Computer Networks and Communications, Universal Wiser, pp. 2 - 16, 2023.
Abstract | Links | BibTeX | Tags:
@article{4670,
title = {Long Range Based IoT Search and Rescue System, a Human- Computer Interaction Preliminary Study and Implementation},
author = {Christos Bouras and Apostolos Gkamas and Spyridon Aniceto Katsampiris Salgado},
url = {https://telematics3.upatras.gr/wp-content/uploads/2024/06/CNC2023_Bouras1.pdf},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Computer Networks and Communications, Universal Wiser},
pages = {2 - 16},
abstract = {Nowadays, IoT has been introduced in different aspects of our lives giving solutions to several problems, one of which is the Search and Rescue (SAR) operations. People that suffer from dementia or people with disease in the autism spectrum tend to elope from their caretaker’s attention, a fact that can lead to serious problems. Thus, a system that takes into consideration of the multiple requirements is of paramount importance. In this paper, a LoRa based SAR system is proposed in order to help in the localization of people with high risk of going missing. In contrast to most of the related systems, in this research article a different approach has been followed. Instead of focusing on the technology, in our approach a human-centered design has been used, leveraging the knowledge of Human-Computer Interaction (HCI) domain. Thus, the technologies used, are an outcome of the initial study. Finally, the system is evaluated using heuristic evaluation and questionnaires},
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Nowadays, IoT has been introduced in different aspects of our lives giving solutions to several problems, one of which is the Search and Rescue (SAR) operations. People that suffer from dementia or people with disease in the autism spectrum tend to elope from their caretaker’s attention, a fact that can lead to serious problems. Thus, a system that takes into consideration of the multiple requirements is of paramount importance. In this paper, a LoRa based SAR system is proposed in order to help in the localization of people with high risk of going missing. In contrast to most of the related systems, in this research article a different approach has been followed. Instead of focusing on the technology, in our approach a human-centered design has been used, leveraging the knowledge of Human-Computer Interaction (HCI) domain. Thus, the technologies used, are an outcome of the initial study. Finally, the system is evaluated using heuristic evaluation and questionnaires
Bouras, Christos; Gkamas, Apostolos; Kokkinos, Vasileios; Papachristos, Nikolaos
Performance Evaluation of Monitoring IoT Systems using LoRaWan Journal Article
In: Telecommunication Systems, Springer Verlang, pp. 295 - 308 , 2021.
Abstract | Links | BibTeX | Tags:
@article{4576,
title = {Performance Evaluation of Monitoring IoT Systems using LoRaWan},
author = {Christos Bouras and Apostolos Gkamas and Vasileios Kokkinos and Nikolaos Papachristos},
url = {https://telematics3.upatras.gr/telecommunicationssystems2021/},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Telecommunication Systems, Springer Verlang},
pages = {295 - 308 },
abstract = {The proliferation of smart devices, or even better, IoT devices, has led to the widespread development of applications that take advantage of these devices. Of particular interest is the precise localization of such a device. However, these use cases become extremely difficult when connectivity to end-devices is required even in areas where the signal is too low or different technologies co-exist for the transmission of the data. In this research work, we study LoRaWan and Wi-Fi as two possible candidates for data transmission. We are particularly focused on the study of the above technologies in terms of performance as well as application development that can be used as rescue monitoring systems. For this reason, we start by describing LoRa as an ideal low power and long-distance communication protocol on the IoT devices compared to the Wi-Fi network. We perform various simulations in terms of time on air transmission, bit error rate by changing important metrics to study the behavior of the whole mechanism. Based on our simulations, the main findings highlight that the contribution of a Spreading Factor (SF) and bandwidth (BW) optimizations can be applied to real hardware for real Search and Rescue (SAR) cases giving improved results in case of coverage and battery extension applications. As a continuation of our research, we developed a monitor application that collects and visualizes data from end-nodes (wearables). These data are processed gateway and network server to The Things Network (TTN) for further analysis. The proposed solution can be used in different rescue monitor scenarios such as identifying and find individuals of vulnerable groups or those belonging to group of people with a high probability of being lost. The purpose of the above solution is to overcome monitor problems on SAR cases, compare with WiFi and suggest a module supporting both technologies in order to be used in real experiments.},
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The proliferation of smart devices, or even better, IoT devices, has led to the widespread development of applications that take advantage of these devices. Of particular interest is the precise localization of such a device. However, these use cases become extremely difficult when connectivity to end-devices is required even in areas where the signal is too low or different technologies co-exist for the transmission of the data. In this research work, we study LoRaWan and Wi-Fi as two possible candidates for data transmission. We are particularly focused on the study of the above technologies in terms of performance as well as application development that can be used as rescue monitoring systems. For this reason, we start by describing LoRa as an ideal low power and long-distance communication protocol on the IoT devices compared to the Wi-Fi network. We perform various simulations in terms of time on air transmission, bit error rate by changing important metrics to study the behavior of the whole mechanism. Based on our simulations, the main findings highlight that the contribution of a Spreading Factor (SF) and bandwidth (BW) optimizations can be applied to real hardware for real Search and Rescue (SAR) cases giving improved results in case of coverage and battery extension applications. As a continuation of our research, we developed a monitor application that collects and visualizes data from end-nodes (wearables). These data are processed gateway and network server to The Things Network (TTN) for further analysis. The proposed solution can be used in different rescue monitor scenarios such as identifying and find individuals of vulnerable groups or those belonging to group of people with a high probability of being lost. The purpose of the above solution is to overcome monitor problems on SAR cases, compare with WiFi and suggest a module supporting both technologies in order to be used in real experiments.
Bouras, Christos; Gkamas, Apostolos; Katsampiris, Spyridon; Papachristos, Nikolaos
A Comparative Study of Machine Learning Models for Spreading Factor Selection in LoRa Networks Journal Article
In: Journal of Wireless Networks and Broadband Technologies (IJWNBT), IGI Global, vol. 10, pp. 100-121, 2021.
Abstract | Links | BibTeX | Tags:
@article{4519,
title = {A Comparative Study of Machine Learning Models for Spreading Factor Selection in LoRa Networks},
author = {Christos Bouras and Apostolos Gkamas and Spyridon Katsampiris and Nikolaos Papachristos},
url = {https://telematics3.upatras.gr/a-comparative-study-of-machine-learning-models-for-spreading-factor-selection-in-lora-networks/},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Journal of Wireless Networks and Broadband Technologies (IJWNBT), IGI Global},
volume = {10},
pages = {100-121},
abstract = {Low Power Wide Area Networks (LPWAN) technologies offer reasonably priced connectivity to a large number of low-power devices spread over great geographical ranges. Long Range (LoRa) is a LPWAN technology that empowers energy-efficient communication. In LoRaWAN networks collisions are strongly correlated with Spreading Factor (SF) assignment of end-nodes which affects network performance. In this work, SF assignment using Machine Learning models in simulation environment is presented. This work examines three approaches for the selection of the SF during LoRa transmissions a) random SF assignment b) Adaptive Data Rate (ADR) and c) SF selection through Machine Learning (ML). The main target is to study and determine the most efficient approach as well as to investigate the benefits of using ML techniques in the context of LoRa networks. In this research a library that enables the communication between ML libraries and OMNeT++ simulator was created. The performance of the approaches is evaluated for different scenarios, using the delivery ratio and energy consumption metrics.},
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Low Power Wide Area Networks (LPWAN) technologies offer reasonably priced connectivity to a large number of low-power devices spread over great geographical ranges. Long Range (LoRa) is a LPWAN technology that empowers energy-efficient communication. In LoRaWAN networks collisions are strongly correlated with Spreading Factor (SF) assignment of end-nodes which affects network performance. In this work, SF assignment using Machine Learning models in simulation environment is presented. This work examines three approaches for the selection of the SF during LoRa transmissions a) random SF assignment b) Adaptive Data Rate (ADR) and c) SF selection through Machine Learning (ML). The main target is to study and determine the most efficient approach as well as to investigate the benefits of using ML techniques in the context of LoRa networks. In this research a library that enables the communication between ML libraries and OMNeT++ simulator was created. The performance of the approaches is evaluated for different scenarios, using the delivery ratio and energy consumption metrics.
Bouras, Christos; Gkamas, Apostolos; Katsampiris, Spyridon
Energy efficient mechanism for LoRa networks Journal Article
In: Internet of Things: Engineering Cyber Physical Human Systems, Elsevier Science, 2021, vol. 13, pp. 1-13, 2021.
Abstract | Links | BibTeX | Tags:
@article{4510,
title = {Energy efficient mechanism for LoRa networks},
author = {Christos Bouras and Apostolos Gkamas and Spyridon Katsampiris},
url = {https://telematics3.upatras.gr/1-s2-0-s2542660521000044-main/},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Internet of Things: Engineering Cyber Physical Human Systems, Elsevier Science, 2021},
volume = {13},
pages = {1-13},
abstract = {Internet of Things (IoT) is the ability of communication between objects and refers to a wide range of applications, such as the Search and Rescue (SAR) operations. SAR applications need long distance connectivity, thus can be benefited by Low Power Wide Area Networks (LPWAN). One LPWAN technology is called LoRa (Long Range). In this context, the WeSAR project has been created that provides a system for locating and rescuing people, especially those who belong to population groups with a very high probability of getting lost. The energy consumption of the wearable devices is important factor in the SAR operations, as the battery should last more than 45 50 hours. Therefore, the proposed system is based on LoRa technology, the user localization is based on LoRa using trilateration and Time Difference of Arrival (TDoA) instead of Geolocation Positioning System (GPS), as GPS increases the energy consumption, and we created an energy-efficient mechanism to tackle the problem of energy consumption. In this paper, an energy efficient mechanism for LoRa networks is presented, that is based on the user’s state and the battery level of the wearable device. Realistic simulations have been conducted to evaluate the system for both one wearable device, and multiple wearable devices, using different mobility models. The results from the simulations have shown a decrease in the energy consumption in various node mobility models that were tested, without compromising the delivery ratio of the network, something important as the LoRa packets are used for the localization of the lost person.},
keywords = {},
pubstate = {published},
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}
Internet of Things (IoT) is the ability of communication between objects and refers to a wide range of applications, such as the Search and Rescue (SAR) operations. SAR applications need long distance connectivity, thus can be benefited by Low Power Wide Area Networks (LPWAN). One LPWAN technology is called LoRa (Long Range). In this context, the WeSAR project has been created that provides a system for locating and rescuing people, especially those who belong to population groups with a very high probability of getting lost. The energy consumption of the wearable devices is important factor in the SAR operations, as the battery should last more than 45 50 hours. Therefore, the proposed system is based on LoRa technology, the user localization is based on LoRa using trilateration and Time Difference of Arrival (TDoA) instead of Geolocation Positioning System (GPS), as GPS increases the energy consumption, and we created an energy-efficient mechanism to tackle the problem of energy consumption. In this paper, an energy efficient mechanism for LoRa networks is presented, that is based on the user’s state and the battery level of the wearable device. Realistic simulations have been conducted to evaluate the system for both one wearable device, and multiple wearable devices, using different mobility models. The results from the simulations have shown a decrease in the energy consumption in various node mobility models that were tested, without compromising the delivery ratio of the network, something important as the LoRa packets are used for the localization of the lost person.
Bouras, Christos; Gkamas, Apostolos; Kokkinos, Vasileios; Papachristos, Nikolaos
Geolocation analysis for SAR systems using LoRaWAN Journal Article
In: International Journal of Communication Systems, Wiley InterScience, pp. 1 - 16, 2020.
Abstract | Links | BibTeX | Tags:
@article{4487,
title = {Geolocation analysis for SAR systems using LoRaWAN},
author = {Christos Bouras and Apostolos Gkamas and Vasileios Kokkinos and Nikolaos Papachristos},
url = {https://telematics3.upatras.gr/dac-4593/},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {International Journal of Communication Systems, Wiley InterScience},
pages = {1 - 16},
abstract = {Low Power Wide Area Network (LPWAN) technologies aiming to provide power-efficient solutions to the field of Internet of Things (IoT). Over the last years we have seen a significant development within the area of IoT applications. For many applications, the problem of localization (i.e. determine the physical location of nodes) is critical. An area study of such use case is also the rescue monitor systems. In this study, we start by describing a solution designed for the Long Range Wide Area Network (LoRaWAN) to localize position of IoT modules such as wearables used from vulnerable groups. Through performance study of the behavior of a LoRaWAN channel and using trilateration and RSSI information, the localization of an IoT wearable can be acquired within a small range. Routing people in need is one of the use cases the above mechanism could be integrated so as to be able to be tracked by familiar people. After that, we evaluate the usage of mathematical model of multilateration algorithms using Time Difference of Arrival (TDoA) as a solution for positioning over LoRaWAN. The research is carried out using simulations in Python by configuring the constant positions of the Gateways inside an outdoor area. The proposed algorithms can be integrated in application for tracking people at any time and especially routing people from vulnerable groups. Through multilateration and algorithm’s prediction, we can have an accuracy of 40-60m in location positioning, ideal for search and rescue use cases. We finally summarize the above algorithms’ estimation and general behavior in a SAR system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Low Power Wide Area Network (LPWAN) technologies aiming to provide power-efficient solutions to the field of Internet of Things (IoT). Over the last years we have seen a significant development within the area of IoT applications. For many applications, the problem of localization (i.e. determine the physical location of nodes) is critical. An area study of such use case is also the rescue monitor systems. In this study, we start by describing a solution designed for the Long Range Wide Area Network (LoRaWAN) to localize position of IoT modules such as wearables used from vulnerable groups. Through performance study of the behavior of a LoRaWAN channel and using trilateration and RSSI information, the localization of an IoT wearable can be acquired within a small range. Routing people in need is one of the use cases the above mechanism could be integrated so as to be able to be tracked by familiar people. After that, we evaluate the usage of mathematical model of multilateration algorithms using Time Difference of Arrival (TDoA) as a solution for positioning over LoRaWAN. The research is carried out using simulations in Python by configuring the constant positions of the Gateways inside an outdoor area. The proposed algorithms can be integrated in application for tracking people at any time and especially routing people from vulnerable groups. Through multilateration and algorithm’s prediction, we can have an accuracy of 40-60m in location positioning, ideal for search and rescue use cases. We finally summarize the above algorithms’ estimation and general behavior in a SAR system.
Barri, Eirini; Bouras, Christos; Gkamas, Apostolos; Katsampiris, Spyridon
GuideMe: A Complete System for Indoor Orientation and Guidance Journal Article
In: International Journal of Smart Sensor Technologies and Applications (IJSSTA), IGI Global, vol. 1, pp. 36-53, 2020.
Abstract | Links | BibTeX | Tags:
@article{4567,
title = {GuideMe: A Complete System for Indoor Orientation and Guidance},
author = {Eirini Barri and Christos Bouras and Apostolos Gkamas and Spyridon Katsampiris},
url = {https://telematics3.upatras.gr/guideme-a-complete-system-for-indoor-orientation-and-guidance-2/},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {International Journal of Smart Sensor Technologies and Applications (IJSSTA), IGI Global},
volume = {1},
pages = {36-53},
abstract = {The interest for indoor navigational systems is expanding daily with concerns among visually impaired people who cannot navigate safely indoors. The main goal of such systems is the localization and direction of the individual who has a wearable device that provides voice commands to navigate indoor buildings. This paper aims to present the design and the implementation of the GuideMe project. The GuideMe project’s goal is the design, implementation, and evaluation of a navigation system focused on people who face troubles in indoor moving utilizing a wearable device. Specifically, the focus group is people suffering from visual impairment. The person carrying the wearable device takes guidelines about the location from indoor ultrawide band (UWB) anchors. The commands provided are about indoor direction through voice commands, assisting him to avoid obstacles in his route. The authors present the architecture and the details of the various modules, which consist of the proposed indoor navigation system, and some initial evaluations of the proposed system yielding promising results.},
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pubstate = {published},
tppubtype = {article}
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The interest for indoor navigational systems is expanding daily with concerns among visually impaired people who cannot navigate safely indoors. The main goal of such systems is the localization and direction of the individual who has a wearable device that provides voice commands to navigate indoor buildings. This paper aims to present the design and the implementation of the GuideMe project. The GuideMe project’s goal is the design, implementation, and evaluation of a navigation system focused on people who face troubles in indoor moving utilizing a wearable device. Specifically, the focus group is people suffering from visual impairment. The person carrying the wearable device takes guidelines about the location from indoor ultrawide band (UWB) anchors. The commands provided are about indoor direction through voice commands, assisting him to avoid obstacles in his route. The authors present the architecture and the details of the various modules, which consist of the proposed indoor navigation system, and some initial evaluations of the proposed system yielding promising results.
Bouras, Christos; Diles, Georgios; Gkamas, Apostolos; Zacharopoulos, Andreas
A comparative study of 4G and 5G Network Simulators Journal Article
In: International Journal on Advances in Networks and Services, IARIA, vol. 13, pp. 11-20, 2020.
Abstract | Links | BibTeX | Tags:
@article{4467,
title = {A comparative study of 4G and 5G Network Simulators},
author = {Christos Bouras and Georgios Diles and Apostolos Gkamas and Andreas Zacharopoulos},
url = {https://telematics3.upatras.gr/netser_v13_n12_2020_paged/},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {International Journal on Advances in Networks and Services, IARIA},
volume = {13},
pages = {11-20},
abstract = {Network simulation is a technique of utmost importance to evaluate new network performance, verify new algorithms and analyze various network topologies. It is used to find results to be expected from a hardware setup without the need for actual implementation. For this reason, there is a plethora of Network Simulation Software applied to different scenarios to evaluate theories and hypotheses. A cellular network is an example of an extremely complex system in which different components impact the overall performance in different ways. The aim of this paper is to study the most common Simulators regarding the deployment of 4G and 5G networks, provide a detailed comparison featuring their main advantages and showcasing potential defects and support the academic community, offering the required data to help choose the necessary one.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Network simulation is a technique of utmost importance to evaluate new network performance, verify new algorithms and analyze various network topologies. It is used to find results to be expected from a hardware setup without the need for actual implementation. For this reason, there is a plethora of Network Simulation Software applied to different scenarios to evaluate theories and hypotheses. A cellular network is an example of an extremely complex system in which different components impact the overall performance in different ways. The aim of this paper is to study the most common Simulators regarding the deployment of 4G and 5G networks, provide a detailed comparison featuring their main advantages and showcasing potential defects and support the academic community, offering the required data to help choose the necessary one.
Bouras, Christos; Gkamas, Apostolos; Kapoulas, Vaggelis; Politaki, Dimitra; Tsanai, Enea
Video transmission in mobile ad hoc networks using multiple interfaces and multiple channels Journal Article
In: International Journal of Communication Systems, Wiley InterScience, vol. 8, pp. 1-28, 2017.
Abstract | Links | BibTeX | Tags:
@article{4131,
title = {Video transmission in mobile ad hoc networks using multiple interfaces and multiple channels},
author = {Christos Bouras and Apostolos Gkamas and Vaggelis Kapoulas and Dimitra Politaki and Enea Tsanai},
url = {https://telematics3.upatras.gr/ijcs/},
year = {2017},
date = {2017-05-01},
urldate = {2017-05-01},
journal = {International Journal of Communication Systems, Wiley InterScience},
volume = {8},
pages = {1-28},
abstract = {Mobile Ad hoc NETworks (MANETs) are an important part of wireless communications and the increasing use of mobile devices is confirming that. MANETs can be of great value in Emergency Response situations where communication between mobile deployed units is critical and wired or wireless infrastructures may not be present or functional. In emergency scenarios, multimedia communication is very important for decision making and situation assessment. This requires up-to-date (on-line) information feed on the situation, including voice and video from the affected zone. However, MANETs do not seem to efficiently support multimedia applications, and this is quite evident in video transmission. One way to remedy this is to use more (wireless) interfaces per mobile node and consequently more communication channels. In this work, we perform an analytical study on the use of multiple interfaces and multiple channels (MIMC) in video transmission with respect to the requirements of Emergency Response Ad hoc Networks. More specifically, we examine and present the impact of using MIMC on MANETs during video transmission applications, we evaluate the performance of three basic routing protocols in MANETs, and we propose a channel selection mechanism in MANET nodes with MIMC for enhanced video transmission. In addition, we evaluate video transmission streams with rate adaptation and present comparative results. The proposed mechanism is evaluated using the ns-2 network simulator and the simulations are performed for a variety of topologies. Simulation results show that the different routing protocols respond differently when MIMC is introduced. The Ad hoc On-Demand Multipath Distance Vector and (especially) the Ad hoc On-Demand Distance Vector routing protocols benefit significantly, while the Destination Sequenced Distance Vector shows fewer improvements. The proposed mechanism is shown to be beneficial for transmitting video streams and enhances the network’s ability to accommodate more streams and reduce packet delay.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mobile Ad hoc NETworks (MANETs) are an important part of wireless communications and the increasing use of mobile devices is confirming that. MANETs can be of great value in Emergency Response situations where communication between mobile deployed units is critical and wired or wireless infrastructures may not be present or functional. In emergency scenarios, multimedia communication is very important for decision making and situation assessment. This requires up-to-date (on-line) information feed on the situation, including voice and video from the affected zone. However, MANETs do not seem to efficiently support multimedia applications, and this is quite evident in video transmission. One way to remedy this is to use more (wireless) interfaces per mobile node and consequently more communication channels. In this work, we perform an analytical study on the use of multiple interfaces and multiple channels (MIMC) in video transmission with respect to the requirements of Emergency Response Ad hoc Networks. More specifically, we examine and present the impact of using MIMC on MANETs during video transmission applications, we evaluate the performance of three basic routing protocols in MANETs, and we propose a channel selection mechanism in MANET nodes with MIMC for enhanced video transmission. In addition, we evaluate video transmission streams with rate adaptation and present comparative results. The proposed mechanism is evaluated using the ns-2 network simulator and the simulations are performed for a variety of topologies. Simulation results show that the different routing protocols respond differently when MIMC is introduced. The Ad hoc On-Demand Multipath Distance Vector and (especially) the Ad hoc On-Demand Distance Vector routing protocols benefit significantly, while the Destination Sequenced Distance Vector shows fewer improvements. The proposed mechanism is shown to be beneficial for transmitting video streams and enhances the network’s ability to accommodate more streams and reduce packet delay.
Gkamas, Apostolos; Bouras, Christos; Kioumourtzis, G
Mobile Ad hoc networks (MANETs) for multimedia transmission Journal Article
In: vol. 9, pp. 6239-6248, 2015.
Abstract | Links | BibTeX | Tags:
@article{3434,
title = {Mobile Ad hoc networks (MANETs) for multimedia transmission},
author = {Apostolos Gkamas and Christos Bouras and G Kioumourtzis},
url = {https://telematics3.upatras.gr/mobile-ad-hoc-networks-manets-for-multimedia-transmission-2/},
year = {2015},
date = {2015-01-01},
urldate = {2015-01-01},
volume = {9},
pages = {6239-6248},
publisher = {Encyclopedia of Information Science and Technology (3rd Ed.), IGI Global},
edition = {3rd},
chapter = {614},
abstract = {Mobile Ad hoc Networks (MANETs) are becoming more essential to wireless communications due to growing popularity of mobile devices. A node in MANETs could act as a router while having also the possibility of being the sender or receiver of information. MANETs offer the freedom to use mobile devices and move independently of the location of base stations (and outside their coverage) with the help of other network devices. The ability of MANETs to be self-configured and form a mobile mesh network, by using wireless links, make them very suitable for a number of cases that other type of networks cannot operate. In addition, MANETs do not require vast technological investments. An ideal application area for the utilization of MANET technology is for instance any disaster scenario in which the fixed infrastructure is incapacitated or non-existent. In this case it is important to ensure that a suitable communication solution is established within the very first critical hours of an incident, considering national or cross-border emergency incidents. What is missing, however, from this type of networks is the so called a “killer application” that could boost its utilizations in the real world. Real time multimedia applications have the potential to turn MANETs into a very attractive solution in wireless networks taking into account its unique characteristics. Our motivation for this article is to present the shortcomings and the current state of the art in MANETs in regards to the transmission of multimedia data, which is a promising application area.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mobile Ad hoc Networks (MANETs) are becoming more essential to wireless communications due to growing popularity of mobile devices. A node in MANETs could act as a router while having also the possibility of being the sender or receiver of information. MANETs offer the freedom to use mobile devices and move independently of the location of base stations (and outside their coverage) with the help of other network devices. The ability of MANETs to be self-configured and form a mobile mesh network, by using wireless links, make them very suitable for a number of cases that other type of networks cannot operate. In addition, MANETs do not require vast technological investments. An ideal application area for the utilization of MANET technology is for instance any disaster scenario in which the fixed infrastructure is incapacitated or non-existent. In this case it is important to ensure that a suitable communication solution is established within the very first critical hours of an incident, considering national or cross-border emergency incidents. What is missing, however, from this type of networks is the so called a “killer application” that could boost its utilizations in the real world. Real time multimedia applications have the potential to turn MANETs into a very attractive solution in wireless networks taking into account its unique characteristics. Our motivation for this article is to present the shortcomings and the current state of the art in MANETs in regards to the transmission of multimedia data, which is a promising application area.
Adam, George; Bouras, Christos; Gkamas, Apostolos; Kapoulas, Vaggelis; Kioumourtzis, G
Cross Layer Design for Video Streaming in MANETs Journal Article
In: Journal of Networks, Academy Publishers, vol. 9, No. 2, pp. 328-338, 2014.
Abstract | Links | BibTeX | Tags:
@article{3441,
title = {Cross Layer Design for Video Streaming in MANETs},
author = {George Adam and Christos Bouras and Apostolos Gkamas and Vaggelis Kapoulas and G Kioumourtzis},
url = {https://telematics3.upatras.gr/26fa4fa910299646670c90f124817d870a1e/},
year = {2014},
date = {2014-01-01},
urldate = {2014-01-01},
journal = {Journal of Networks, Academy Publishers},
volume = {9, No. 2},
pages = {328-338},
abstract = {Mobile Ad hoc NETworks (MANETs) are becoming more essential to wireless communications due to growing popularity of mobile devices. However, MANETs do not seem to effectively support multimedia applications and especially video transmission. In this work, we propose a cross-layer design that aims to improve the performance of video transmission using TCP Friendly Rate Control (TFRC). Our design provides priority to video packets and exploits information from the MAC layer in order to improve TFRCs performance. The proposed cross-layer design utilizes SNR measurements along the routing path, in order to make the route reconstruction procedure more efficient. Simulation results show that both the use of traffic classification and the SNR utilization lead to important improvements in terms of end-to-end Quality of Service (QoS).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mobile Ad hoc NETworks (MANETs) are becoming more essential to wireless communications due to growing popularity of mobile devices. However, MANETs do not seem to effectively support multimedia applications and especially video transmission. In this work, we propose a cross-layer design that aims to improve the performance of video transmission using TCP Friendly Rate Control (TFRC). Our design provides priority to video packets and exploits information from the MAC layer in order to improve TFRCs performance. The proposed cross-layer design utilizes SNR measurements along the routing path, in order to make the route reconstruction procedure more efficient. Simulation results show that both the use of traffic classification and the SNR utilization lead to important improvements in terms of end-to-end Quality of Service (QoS).
Bouras, Christos; Gkamas, Apostolos; Kioumourtzis, G
TFMCC vs ASMP: Lessons learned from performance evaluation Journal Article
In: International Journal of Network Management, Wiley InterScience, pp. 349-372, vol. 22, pp. 349 - 372, 2012.
Abstract | Links | BibTeX | Tags:
@article{3112,
title = {TFMCC vs ASMP: Lessons learned from performance evaluation},
author = {Christos Bouras and Apostolos Gkamas and G Kioumourtzis},
url = {https://telematics3.upatras.gr/4081nem810/},
year = {2012},
date = {2012-01-01},
urldate = {2012-01-01},
journal = {International Journal of Network Management, Wiley InterScience, pp. 349-372},
volume = {22},
pages = {349 - 372},
abstract = {In this article we present a simulation-based comparison of one of the best-known multicast congestion control schemes—TCP-friendly Multicast Congestion Control (TFMCC)—against our proposed Adaptive Smooth Multicast Protocol (ASMP). ASMP consists of a single-rate multicast congestion control mechanism which takes advantage of the RTCP Sender (SR) and Receiver Reports (RR) in order to adjust the sender?s transmission rate in respect of the network conditions. The innovation in ASMP lays in the ?smooth? transmission rate, which is TCP-friendly and prevents oscillations. We use an integrated simulation environment named Multi- Evalvid-RA for the evaluation of the two congestion control schemes. Multi-Evalvid-RA provides all the necessary tools to perform simulation studies and assess video quality by using both network-centric metrics along with video quality measurements. Performance evaluation results show that ASMP is a very efficient solution for rate-adaptive multimedia applications and a serious competitor to well-known TFMCC.},
keywords = {},
pubstate = {published},
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}
In this article we present a simulation-based comparison of one of the best-known multicast congestion control schemes—TCP-friendly Multicast Congestion Control (TFMCC)—against our proposed Adaptive Smooth Multicast Protocol (ASMP). ASMP consists of a single-rate multicast congestion control mechanism which takes advantage of the RTCP Sender (SR) and Receiver Reports (RR) in order to adjust the sender?s transmission rate in respect of the network conditions. The innovation in ASMP lays in the ?smooth? transmission rate, which is TCP-friendly and prevents oscillations. We use an integrated simulation environment named Multi- Evalvid-RA for the evaluation of the two congestion control schemes. Multi-Evalvid-RA provides all the necessary tools to perform simulation studies and assess video quality by using both network-centric metrics along with video quality measurements. Performance evaluation results show that ASMP is a very efficient solution for rate-adaptive multimedia applications and a serious competitor to well-known TFMCC.
Bouras, Christos; Gkamas, Apostolos; Kioumourtzis, G
Performance Evaluation of Ad Hoc Routing Protocols for Military Communications Journal Article
In: International Journal of Network Management, Wiley InterScience, pp. 216-234, pp. 216 - 234, 2012.
Abstract | Links | BibTeX | Tags:
@article{3106,
title = {Performance Evaluation of Ad Hoc Routing Protocols for Military Communications},
author = {Christos Bouras and Apostolos Gkamas and G Kioumourtzis},
url = {https://telematics3.upatras.gr/2078nem802/},
year = {2012},
date = {2012-01-01},
urldate = {2012-01-01},
journal = {International Journal of Network Management, Wiley InterScience, pp. 216-234},
pages = {216 - 234},
abstract = {Mobile Ad hoc networks (MANETs) are of much interest to both the research community and the military because of the potential to establish a communication network in any situation that involves emergencies. Examples are search-and-rescue operations, military deployment in hostile environment, and several types of police operations.
One critical open issue is how to route messages considering the characteristics of these networks. The nodes act as routers in an environment without a fixed infrastructure, the nodes are mobile, the wireless medium has its own limitations compared to wired networks, and existing routing protocols cannot be employed at least without modifications. Over the last few years, a number of routing protocols have been proposed and enhanced to address the issue of routing in MANETs. It is not clear how those different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. This article provides an analysis and performance evaluation of those protocols that may be suitable for military communications. The evaluation is conducted in two phases. In the first phase, we compare the protocols based on qualitative metrics to locate those that may be fit our evaluation criteria. In the second phase, we evaluate the selected protocols from the first phase based on quantitative metrics in a mobility scenario that reflects tactical military movements. The results disclose that there is no routing protocol in the current stage without modifications that can provide efficient routing to any size of network, regardless the number of nodes and the network load and mobility.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mobile Ad hoc networks (MANETs) are of much interest to both the research community and the military because of the potential to establish a communication network in any situation that involves emergencies. Examples are search-and-rescue operations, military deployment in hostile environment, and several types of police operations.
One critical open issue is how to route messages considering the characteristics of these networks. The nodes act as routers in an environment without a fixed infrastructure, the nodes are mobile, the wireless medium has its own limitations compared to wired networks, and existing routing protocols cannot be employed at least without modifications. Over the last few years, a number of routing protocols have been proposed and enhanced to address the issue of routing in MANETs. It is not clear how those different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. This article provides an analysis and performance evaluation of those protocols that may be suitable for military communications. The evaluation is conducted in two phases. In the first phase, we compare the protocols based on qualitative metrics to locate those that may be fit our evaluation criteria. In the second phase, we evaluate the selected protocols from the first phase based on quantitative metrics in a mobility scenario that reflects tactical military movements. The results disclose that there is no routing protocol in the current stage without modifications that can provide efficient routing to any size of network, regardless the number of nodes and the network load and mobility.
One critical open issue is how to route messages considering the characteristics of these networks. The nodes act as routers in an environment without a fixed infrastructure, the nodes are mobile, the wireless medium has its own limitations compared to wired networks, and existing routing protocols cannot be employed at least without modifications. Over the last few years, a number of routing protocols have been proposed and enhanced to address the issue of routing in MANETs. It is not clear how those different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. This article provides an analysis and performance evaluation of those protocols that may be suitable for military communications. The evaluation is conducted in two phases. In the first phase, we compare the protocols based on qualitative metrics to locate those that may be fit our evaluation criteria. In the second phase, we evaluate the selected protocols from the first phase based on quantitative metrics in a mobility scenario that reflects tactical military movements. The results disclose that there is no routing protocol in the current stage without modifications that can provide efficient routing to any size of network, regardless the number of nodes and the network load and mobility.
Bouras, Christos; Kapoulas, Vaggelis; Gkamas, Apostolos; Stamos, Kostas; Papapanagiotou, Vassilis; Zaoudis, Giannis
Power Management Adaptation Techniques for Video transmission over TFRC Journal Article
In: International Journal of Network Management, Wiley InterScience, pp. 414 -431, vol. 25, pp. 414 -431, 2011.
Abstract | Links | BibTeX | Tags:
@article{3102,
title = {Power Management Adaptation Techniques for Video transmission over TFRC},
author = {Christos Bouras and Vaggelis Kapoulas and Apostolos Gkamas and Kostas Stamos and Vassilis Papapanagiotou and Giannis Zaoudis},
url = {https://telematics3.upatras.gr/3259ijnm2011/},
year = {2011},
date = {2011-01-01},
urldate = {2011-01-01},
journal = {International Journal of Network Management, Wiley InterScience, pp. 414 -431},
volume = {25},
pages = {414 -431},
abstract = {In this paper, we describe power management adaptation techniques for wireless video transmission using the TFRC protocol that take into account feedback about the received video quality and try to intelligently adapt transmitting power accordingly. The purpose of the mechanisms is to utilize TFRC feedback and thus achieve a beneficial balance between the power consumption and the received video quality. There are 2 power adaptation mechanisms proposed, each one with its own advantages. They both offer significant improvements when used in terms of both power consumption and received video quality. We use simulation in order to compare and evaluate our approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, we describe power management adaptation techniques for wireless video transmission using the TFRC protocol that take into account feedback about the received video quality and try to intelligently adapt transmitting power accordingly. The purpose of the mechanisms is to utilize TFRC feedback and thus achieve a beneficial balance between the power consumption and the received video quality. There are 2 power adaptation mechanisms proposed, each one with its own advantages. They both offer significant improvements when used in terms of both power consumption and received video quality. We use simulation in order to compare and evaluate our approach.
Bouras, Christos; Gkamas, Apostolos; Kioumourtzis, G
Adaptive Smooth Simulcast Protocol (ASSP) for Video Applications: Description and Performance Evaluation Journal Article
In: Journal of Network and Systems Management, Springer Verlang, pp. 143-177, pp. 143 - 177, 2011.
Abstract | Links | BibTeX | Tags:
@article{3097,
title = {Adaptive Smooth Simulcast Protocol (ASSP) for Video Applications: Description and Performance Evaluation},
author = {Christos Bouras and Apostolos Gkamas and G Kioumourtzis},
url = {https://telematics3.upatras.gr/6420jnsm2011_bouras/},
year = {2011},
date = {2011-01-01},
urldate = {2011-01-01},
journal = {Journal of Network and Systems Management, Springer Verlang, pp. 143-177},
pages = {143 - 177},
abstract = {In this paper, we present Adaptive Smooth Simulcast Protocol (ASSP) for simulcast transmission of multimedia data over best-effort networks. ASSP is a new multiple-rate protocol that implements a single rate TCP-friendly protocol as the underlying congestion control mechanism for each simulcast stream. The key attributes of ASSP are: (a) TCP-friendly behavior, (b) adaptive per-stream transmission rates, (c) adaptive scalability to large sets of receivers and (d) smooth transmission rates that are suitable for multimedia applications. We evaluate the performance of ASSP under an integrated simulation environment which combines the measurements of both network and video performance metrics. We also compare ASSP against other proposed solutions and the results demonstrate that the performance of ASSP is significantly better than the tested solutions. Finally, ASSP is a practical solution with very low implementation complexity for video transmission over best-effort networks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, we present Adaptive Smooth Simulcast Protocol (ASSP) for simulcast transmission of multimedia data over best-effort networks. ASSP is a new multiple-rate protocol that implements a single rate TCP-friendly protocol as the underlying congestion control mechanism for each simulcast stream. The key attributes of ASSP are: (a) TCP-friendly behavior, (b) adaptive per-stream transmission rates, (c) adaptive scalability to large sets of receivers and (d) smooth transmission rates that are suitable for multimedia applications. We evaluate the performance of ASSP under an integrated simulation environment which combines the measurements of both network and video performance metrics. We also compare ASSP against other proposed solutions and the results demonstrate that the performance of ASSP is significantly better than the tested solutions. Finally, ASSP is a practical solution with very low implementation complexity for video transmission over best-effort networks.
Bouras, Christos; Gkamas, Apostolos; Kioumourtzis, G
Adaptive Smooth Multicast Protocol for Multimedia Transmission: Implementation Details and Performance Evaluation Journal Article
In: International Journal of Communication Systems, Wiley InterScience, pp. 299-333, vol. 23, pp. 299 - 333, 2010.
Abstract | Links | BibTeX | Tags:
@article{3094,
title = {Adaptive Smooth Multicast Protocol for Multimedia Transmission: Implementation Details and Performance Evaluation},
author = {Christos Bouras and Apostolos Gkamas and G Kioumourtzis},
url = {https://telematics3.upatras.gr/7062ijcs2009/},
year = {2010},
date = {2010-01-01},
urldate = {2010-01-01},
journal = {International Journal of Communication Systems, Wiley InterScience, pp. 299-333},
volume = {23},
pages = {299 - 333},
abstract = {In this article we propose a new single-rate multicast congestion control scheme named Adaptive Smooth Multicast Protocol (ASMP), for multimedia transmission over best-effort networks. The smoothness lays in the calculation and adaptation of the transmission rate, which is based on dynamic estimations of protocols? parameters and dynamic adjustment of the “smoothness factor”, as well. ASMP key attributes are: a) TCP-friendly behavior, b) adaptive scalability to large sets of receivers, c) high bandwidth utilization, and finally d) smooth transmission rates, which are suitable for multimedia applications. We evaluate the performance of ASMP and investigate its behavior under various network conditions through extensive simulations conducted with the network simulator software (ns2). Simulation results show that ASMP can be regarded as a serious competitor of TFMCC and PGMCC. In many cases, ASMP outperforms TFMCC in terms of TCP-friendliness and smooth transmission rates, while PGMCC presents lower scalability than ASMP. We have implemented ASMP on top of RTP/RTCP protocols in ns2 by adding all the RTP/RTCP protocol?s attributes that are defined in RFC 3550 and related to QoS metrics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this article we propose a new single-rate multicast congestion control scheme named Adaptive Smooth Multicast Protocol (ASMP), for multimedia transmission over best-effort networks. The smoothness lays in the calculation and adaptation of the transmission rate, which is based on dynamic estimations of protocols? parameters and dynamic adjustment of the “smoothness factor”, as well. ASMP key attributes are: a) TCP-friendly behavior, b) adaptive scalability to large sets of receivers, c) high bandwidth utilization, and finally d) smooth transmission rates, which are suitable for multimedia applications. We evaluate the performance of ASMP and investigate its behavior under various network conditions through extensive simulations conducted with the network simulator software (ns2). Simulation results show that ASMP can be regarded as a serious competitor of TFMCC and PGMCC. In many cases, ASMP outperforms TFMCC in terms of TCP-friendliness and smooth transmission rates, while PGMCC presents lower scalability than ASMP. We have implemented ASMP on top of RTP/RTCP protocols in ns2 by adding all the RTP/RTCP protocol?s attributes that are defined in RFC 3550 and related to QoS metrics.
Bouras, Christos; Gkamas, Apostolos; Tsiatsos, Thrasivoulos; Papagiannopoulos, J; Theofilopoulos, George
Broadband Municipal Optical Networks in Greece: A Suitable Business Model Journal Article
In: Journal of Telematics and Informatics, Elsevier Science, pp. 391 - 409, 2009.
Abstract | Links | BibTeX | Tags:
@article{3090,
title = {Broadband Municipal Optical Networks in Greece: A Suitable Business Model},
author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos and J Papagiannopoulos and George Theofilopoulos},
url = {https://telematics3.upatras.gr/4870sdarticle1/},
year = {2009},
date = {2009-01-01},
urldate = {2009-01-01},
journal = {Journal of Telematics and Informatics, Elsevier Science},
pages = {391 - 409},
abstract = {This paper proposes a business model for the optimal exploitation of the currently developing broadband metropolitan area networks in Greece. Having recorded and examined relevant international practices, we describe in detail the way that these networks should be managed, operated, maintained and expanded. Taking into consideration that these infrastructures will widely alter the broadband map of Greece, that Greece has currently one of the lowest broadband penetration percentages in Europe and that the proper exploitation strategy of the networks to be deployed could boost the demand for broadband connections and applications, the application of the optimal business model appears to be of vital importance. We describe the proposed business model in detail, including ways for expanding the broadband infrastructures, as well as tackling of viability issues regarding the authority responsible for managing the broadband metropolitan networks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper proposes a business model for the optimal exploitation of the currently developing broadband metropolitan area networks in Greece. Having recorded and examined relevant international practices, we describe in detail the way that these networks should be managed, operated, maintained and expanded. Taking into consideration that these infrastructures will widely alter the broadband map of Greece, that Greece has currently one of the lowest broadband penetration percentages in Europe and that the proper exploitation strategy of the networks to be deployed could boost the demand for broadband connections and applications, the application of the optimal business model appears to be of vital importance. We describe the proposed business model in detail, including ways for expanding the broadband infrastructures, as well as tackling of viability issues regarding the authority responsible for managing the broadband metropolitan networks.
Bouras, Christos; Gkamas, Apostolos; Stamos, Kostas; Primpas, Dimitris
Adaptive transmission of multimedia data over the Internet [Article in Encyclopedia] Journal Article
In: pp. 16 - 22, 2008.
@article{3159,
title = {Adaptive transmission of multimedia data over the Internet [Article in Encyclopedia]},
author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},
url = {https://telematics3.upatras.gr/358716/},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
pages = {16 - 22},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bouras, Christos; Gkamas, Apostolos; Stamos, Kostas; Primpas, Dimitris
Real-time protocols - RTP/RTCP [Article in Encyclopedia] Journal Article
In: pp. 463 - 468, 2008.
@article{3166,
title = {Real-time protocols - RTP/RTCP [Article in Encyclopedia]},
author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},
url = {https://telematics3.upatras.gr/6733463/},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
pages = {463 - 468},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bouras, Christos; Gkamas, Apostolos; Stamos, Kostas; Primpas, Dimitris
The IPv6 protocol [Article in Encyclopedia] Journal Article
In: pp. 257 - 262, 2008.
@article{3161,
title = {The IPv6 protocol [Article in Encyclopedia]},
author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},
url = {https://telematics3.upatras.gr/2351257/},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
pages = {257 - 262},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bouras, Christos; Gkamas, Apostolos; Tsiatsos, Thrasivoulos; Theofilopoulos, George
Business Models For Municipal Broadband Networks Journal Article
In: pp. 457 - 465, 2008.
@article{3167,
title = {Business Models For Municipal Broadband Networks},
author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos and George Theofilopoulos},
url = {https://telematics3.upatras.gr/3094ist457/},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
pages = {457 - 465},
keywords = {},
pubstate = {published},
tppubtype = {article}
}