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WINES Simulator PDF Print E-mail

WINES - Wireless communIty NEtworks Simulator

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WINES (Wireless communIty NEtworks Simulator) is a network simulator developed by following anAgent Based Modeling and Simulation (ABMS) approach in order to evaluate and analyse, from a high leveltechno-social point of view, the system behaviour of volunteer resource sharing cloud services deployed within wireless community networks (WCN).

The community cloud network architecture implemented in the WINES simulator is based on a hierarchical model similar to that of the well known Guifi.net, populated by different types of nodes, which can be divided into two main categories:

  • Super Nodes (SNs) that effectively extend the network coverage by spreading the traffic to other nodes,

  • Ordinary Nodes (ONs) or terminal nodes which do not extend the connectivity of the network, but act as simple end users

To further extend this classical community cloud architecture where both SNs and ONs are fixed within the network, we envision the participation of Mobile Nodes (MNs) by assessing to the WCN services throughout a wireless connection provided by the ONs, which act as wireless Access Points (AP).
Both ONs and MNs participate to the system as applicants and as resource providers, thus we implemented two separate resource sharing services: hardware resources sharing in terms of Virtual Machines (VM) instances according to the IaaS paradigm, and file sharing, referred to as DATA resources sharing within the simulator.

Localization systems and techniques PDF Print E-mail

Localization techniques using GPS, GSM and Wi-Fi architectures

Perceived Quality of Service - PQoS PDF Print E-mail

Fast and accurate video PQoS estimation over wireless networks

It is well known that the goal of any QoS mechanism is to maintain a good level of user-perceived QoS even when the network conditions are changing unpredictably .
Typical QoS provisioning solutions for multimedia video applications have been always based on the idea of trying to reserve or assure certain network guarantees, so that packets coming from delay or bandwidth sensitive applications receive a better treatment in the network. This approach has been demonstrated to work very well in fixed networks. However, in wireless networks it is not always possible to offer any guarantee, due to continuously changing conditions and unpredictable radio link quality.
Increasing bandwidth is a necessary first step for accommodating real-time streaming applications, however it is not sufficient, due to large bandwidth fluctuations experienced in wireless networks.
Fluctuations in network resource availability due to channel fading, variable error rate, mobility, and handoff, makes QoS provisioning more complex in wireless networks. Moreover, determining how network congestion manifests itself in degraded stream quality is still an open issue and only some very recent studies are available [1][2]. Understanding the relationship between stream quality and network congestion is an important step to solving this problem, and can lead to better design of streaming protocols, computer networks, and content delivery systems.

Cellular Networks PDF Print E-mail

Third-generation mobile communication systems evolve by orienting the integration of three essential domains: broadband, mobile, and the Internet. TITAN Lab has been studying for many years the mobility of an user in a wireless environment. Very relevant research lines are related to user mobility, such as the optimization of the system resources management and the Quality of Service (QoS) provisioning. The former requests to develop handover algorithms, location and paging management, the latter considers call admission control, traffic management and scheduling algorithms.
Through the extensively usage of simulation tools, TITAN Lab analyses and proposes new techniques able to integrate different systems. This integration would pave the way for the fourth generation systems, which will be based on IP traffic and packet switching.

Integrated Satellite-HAP-Terrestrial system PDF Print E-mail

Integrated Satellite-HAP-Terrestrial system architecture: resources allocation and traffic management issues

Next generation satellite systems will provide personal communications to mobile and fixed users. As the demand grows for communication services, wireless solutions are becoming increasingly important. Wireless solutions may solve the ‘last mile’ problem, i.e. the direct services delivery to customer’s premises, offering high-bandwidth services without reliance on a fixed infrastructure. Furthermore, in many scenarios wireless represents the only viable delivery mechanism. A potential solution to the wireless delivery problem lies with aerial platforms, capable of carrying communications relay payloads and operating in a quasi-stationary position at altitudes up to 22km.

The platforms may be airplanes or airships (essentially balloons, termed ‘aerostats’) and may be manned or unmanned with autonomous operation coupled with remote control from the ground. Great interest lies with crafts designed to operate in the stratosphere at an altitude typically between 17 and 22km, which are referred to as high-altitude platforms (HAPs) [1][2][3][4]. This particular range of altitude is due to the wind speed that is slower in the region of 20km. HAPs can offer a wide range of services. Such services may particularly valuable where existing ground infrastructure is missing or difficult.

Multimedia Satellite Systems PDF Print E-mail

Multimedia Satellite Systems (Connection Admission Control Algorithms and Efficient Traffic resources management)

The advent of Ka-band satellites has made small and low-cost user terminals feasible and hastened the development of multimedia satellite networks; a multimedia satellite network is a space-based communications system that interconnects users who are mostly exchanging real time applications based on several data types (e.g., text, voice, images, and video).
The Digital Video Broadcasting by Satellite (DVB-S) standard allows Internet traffic to be multiplexed with traditional video services and broadcasted from a central (or regional) Hub Station to a multitude of terminals within a satellite down-link beam. In the last few years, a direct Return Channel System (RCS) has been standardized by ETSI.

This standard requires a forward link based on a DVB/MPEG-2 data format and a return link using a Multi-Frequency Time Division Multiple Access (MF-TDMA) scheme.A lot of studies have been conducted concerning Connection Admission Control algorithms opportunely designed in order to guarantee a good quality of services at critical traffic sources minimizing the signaling exchange between the on-board and on-earth segments of the system and reducing delays due to the processing of the call requests on board, in addition they present a very low computational complexity reducing at minimum the critical admission time. These algorithms can also guarantee an efficient manage of real-time multimedia video sources both with constant and high variable data rate transmission. A DVB-RCS system architecture using a multi-spot beam geostationary satellite with regenerative payload has been designed and implemented in order to test the robustness and the efficiency of the proposed CAC algorithms also in high load traffic conditions.






Wireless Ad Hoc & Sensor Networks PDF Print E-mail

The decentralized control in wireless systems represents a new paradigm of communications. The possibility of managing the network without any prefixed infrastructure lead to new network technologies called Ad Hoc Networks. This wireless systems present different management modalities in comparison with the traditional infrastructured wireless systems. In ad hoc networks is important to manage the routing protocol in a efficient and adaptive way.
The high mobility can lead to a different deployment of routing protocols in comparison to the protocols proposed for wired networks. Also the MAC layer needs to offer some enhanced functionalities in terms of power consumptions and quality of service. For a particular class of networks called sensor networks, the energy saving is a fundamental issue. Our proposed research is focused on efficient routing strategies for ad hoc and sensor networks. We also propose a MAC layer enhancement in order to offer a basic layer on which we base the routing and transport protocols. Cross layering functionalities for an integrated approach between MAC layer and routing layer are also considered. We believe that Sensor integration, coupled with unceasing electronic miniaturization, will make it possible to produce extremely inexpensive sensing devices.
These devices will be able to monitor a wide variety of ambient conditions: temperature, pressure, humidity. We believe, however, that sensor networks requirements are different enough form those of traditional wired and wireless networks to warrant considering a different design. We are investigating particularly the network and the MAC layer and we are evaluating the fundamental challenging of sensor networks: the low energy consumption.


Wireless Mesh Networks PDF Print E-mail

Wireless Mesh Networks: challenges and open issues

Wireless meshing has been envisioned as the economically viable networking paradigm to build up broadband and large-scale wireless commodity networks. Several different mesh network architectures have been conceived by both industry and academia; however many issues on the deployment of efficient protocol layers are still open.

Wireless Mesh Network (WMN) is a promising wireless technology for several emerging and commercially interesting applications, e.g., broadband home networking, community and neighborhood networks, coordinated network management, intelligent transportation systems. It is gaining significant attention as a possible way for Internet service providers (ISPs) and other end-users to establish robust and reliable wireless broadband service access at a reasonable cost. WMNs consist of mesh routers and mesh clients as shown in Fig. 1.

Wireless Mesh Networks architecture

Fig. 1. An illustration of wireless mesh network architecture. Mesh routers are static nodes equipped with high processing and memory capabilities, while mesh clients have limited memory, computational power.

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