Merkourios Karaliopoulos

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We look into the realization of mobile crowdsensing campaigns that draw on the opportunistic networking paradigm, as practised in delay-tolerant networks but also in the emerging device-to-device communication mode in cellular networks. In particular, we ask how mobile users can be optimally selected in order to generate the required space-time paths across(More)
The main principle behind the working of delay tolerant networks (DTN) is the mobility of the nodes along with their contact sequences for exchanging data. Nodes which are a part of the DTN network can behave selfishly due to network reservation policy, especially when constrained to energy or storage space. Several forwarding protocols exist for spreading(More)
As social networking sites provide increasingly richer context, user-centric service development is expected to explode following the example of User-Generated Content. A major challenge for this emerging paradigm is how to make these exploding in numbers, yet individually of vanishing demand, services available in a cost-effective manner; central to this(More)
Data communication networks are serving all kinds of human activities. Whether used for professional or leisure purposes, for safety-critical applications or e-commerce, the Internet in particular has become an integral part of our everyday lives, affecting the way societies operate. However, the Internet was not intended to serve all these roles and, as(More)
Campus wireless LANs (WLANs) are complex systems with hundreds of access points (APs) and thousands of users. Their performance analysis calls for realistic models of their elements, which can be input to simulation and testbed experiments but also taken into account for theoretical work. However, only few modeling results in this area are derived from real(More)
We investigate the packet-scheduling function within the access scheme of a unidirectional satellite system providing point-to-multipoint services to mobile users. The satellite system may be regarded as an overlay multicast/broadcast layer complementing the point-to-point third generation (3G) mobile terrestrial networks. The satellite access scheme(More)
In this paper we explore the way the discovery of service can be facilitated or not by utilizing service location information that is opportunistically disseminated primarily by the service consumers themselves. We apply our study to the realworld case of parking service in busy city areas. As the vehicles drive around the area, they opportunistically(More)
The elasticity of transmission control protocol (TCP) traffic complicates attempts to provide performance guarantees to TCP flows. The existence of different types of networks and environments on the connections’ paths only aggravates this problem. In this paper, simulation is the primary means for investigating the specific problem in the context of(More)
This paper seeks to systematically explore the efficiency of uncoordinated parking space allocation in urban environments with two types of parking facilities. Drivers decide whether to go for inexpensive but limited on-street parking spots or expensive yet over-dimensioned parking lots, incurring an additional cruising cost when deciding for on-street(More)
This paper proposes a complete satellite access network solution for multimedia broadcast multicast service (MBMS) delivery based on the T-UMTS standards. Firstly, the benefits of MBMS delivery via satellite (SAT-MBMS) for both S/T-UMTS network operators are shown via market and business analysis. A new integrated S/T-UMTS architecture for MBMS delivery is(More)