9,340 research outputs found
Data Connectivity and Smart Group Formation in Wi-Fi Direct Multi-group Networks
Users of Device-to-Device (D2D) communication need efficient content
discovery mechanisms to steer their requests toward
the node in their neighborhood that is most likely to satisfy them.
The problem is further compounded by the lack of a central coordination
entity as well as by the inherent mobility of devices, which leads to volatile topologies.
In this paper, we first discuss group-based communication among non-rooted Android
devices using Wi-Fi Direct, a protocol recently standardized
by the Wi-Fi Alliance. We propose intra- and inter-group communication methodologies,
which we validate through a simple testbed where content-centric routing is used.
Next, we address the autonomous formation of groups with the goal of achieving
efficient device resource utilization as well as full connectivity.
Finally, we evaluate the performance of our group formation procedure both in simulation and
in a real testbed involving Android devices in different topologies
An eco-friendly hybrid urban computing network combining community-based wireless LAN access and wireless sensor networking
Computer-enhanced smart environments, distributed environmental monitoring, wireless communication, energy conservation and sustainable technologies, ubiquitous access to Internet-located data and services, user mobility and innovation as a tool for service differentiation are all significant contemporary research subjects and societal developments. This position paper presents the design of a hybrid municipal network infrastructure that, to a lesser or greater degree, incorporates aspects from each of these topics by integrating a community-based Wi-Fi access network with Wireless Sensor Network (WSN) functionality. The former component provides free wireless Internet connectivity by harvesting the Internet subscriptions of city inhabitants. To minimize session interruptions for mobile clients, this subsystem incorporates technology that achieves (near-)seamless handover between Wi-Fi access points. The WSN component on the other hand renders it feasible to sense physical properties and to realize the Internet of Things (IoT) paradigm. This in turn scaffolds the development of value-added end-user applications that are consumable through the community-powered access network. The WSN subsystem invests substantially in ecological considerations by means of a green distributed reasoning framework and sensor middleware that collaboratively aim to minimize the network's global energy consumption. Via the discussion of two illustrative applications that are currently being developed as part of a concrete smart city deployment, we offer a taste of the myriad of innovative digital services in an extensive spectrum of application domains that is unlocked by the proposed platform
Cooperative data transfers for 5G networks
The demand for higher capacity, higher data rate and larger bandwidth has driven the research and industrial world to develop next generation wireless communication technology, namely, the 5G. Among all the approaches proposed for such a high demand, only the cooperative communication approach promises to significantly improve of the performances (capacity, data rate, bandwidth, etc.) with a low cost. In this thesis, we propose a D2D communication scheme as a solution for the out-door scenario and a cooperative scheme among the access infrastructures as the in-door scenario solution.
In the first part, we address the implementation of content-centric routing in a D2D architecture for Android devices based on WiFi Direct, a protocol recently standardised by the Wi-Fi Alliance. After discussing the creation of multiple D2D groups, we introduce novel paradigms featuring intra- and inter-group bidirectional communication. We then present the primitives involved in content advertising and requesting among members of the multi-group network. In addition to the communications, we also devise a mechanism to enable the devices to spontaneously establish the multi-group D2D network. Finally, we evaluate the performance of our architecture and the network formation mechanism in a real testbed consisting of Android devices.
In the second part, we propose, implement and evaluate a bandwidth aggregation service for residential users that allows to improve the upload throughput of the ADSL connection by leveraging the unused bandwidth of neighboring users. The residential access gateway adopts the 802.11 radio interface to simultaneously serve the local home users and to share the broadband connectivity with neighboring access gateways. Differently from previous works, our aggregation scheme is transparent both for local users, who are not required to modify their applications or device drivers, and for neighboring users, who do not experience any meaningful performance degradation. In order to evaluate the achievable performance and tune the parameters driving the traffic balancing, we developed a fluid model which was shown experimentally to be very accurate. Our proposed scheme is amenable to efficient implementation on Linux networking stack. Indeed, we implemented it and tested in some realistic scenarios, showing an efficient exploitation of the whole available bandwidth, also for legacy cloud storage applications
Content-centric Routing in Wi-Fi Direct Multi-group Networks
The added value of Device-to-Device (D2D) communication amounts to an
efficient content discovery mechanism that enables users to steer their
requests toward the node most likely to satisfy them. In this paper, we address
the implementation of content-centric routing in a D2D architecture for Android
devices based on WiFi Direct, a protocol recently standardised by the Wi-Fi
Alliance. After discussing the creation of multiple D2D groups, we introduce
novel paradigms featuring intra- and inter-group bidirectional communication.
We then present the primitives involved in content advertising and requesting
among members of the multi-group network. Finally, we evaluate the performance
of our architecture in a real testbed involving Android devices in different
group configurations. We also compare the results against the ones achievable
exploiting Bluetooth technologies
Joint Head Selection and Airtime Allocation for Data Dissemination in Mobile Social Networks
Mobile social networks (MSNs) enable people with similar interests to
interact without Internet access. By forming a temporary group, users can
disseminate their data to other interested users in proximity with short-range
communication technologies. However, due to user mobility, airtime available
for users in the same group to disseminate data is limited. In addition, for
practical consideration, a star network topology among users in the group is
expected. For the former, unfair airtime allocation among the users will
undermine their willingness to participate in MSNs. For the latter, a group
head is required to connect other users. These two problems have to be properly
addressed to enable real implementation and adoption of MSNs. To this aim, we
propose a Nash bargaining-based joint head selection and airtime allocation
scheme for data dissemination within the group. Specifically, the bargaining
game of joint head selection and airtime allocation is first formulated. Then,
Nash bargaining solution (NBS) based optimization problems are proposed for a
homogeneous case and a more general heterogeneous case. For both cases, the
existence of solution to the optimization problem is proved, which guarantees
Pareto optimality and proportional fairness. Next, an algorithm, allowing
distributed implementation, for join head selection and airtime allocation is
introduced. Finally, numerical results are presented to evaluate the
performance, validate intuitions and derive insights of the proposed scheme
WiFi-Direct InterNetworking
We are on the verge of having ubiquitous connectivity. However, there are still scenarios
where public communication networks are not reachable, are saturated or simply
cannot be trusted. In such cases, our mobile phones can leverage device-to-device communication
to reach the public network or to enable local connectivity.
A device-to-device communication technology, with at least WiFi speed and range,
will offer sufficient connectivity conditions for interconnection in areas/situations where
it is not currently possible. Such advance will foster a new breed of systems and applications.
Their widespread adoption is, nonetheless, bound to their usage in off-the-shelf
devices. This raises a problem because the device-to-device communication technologies
currently available in off-the-shelf mobile devices have several limitations: Bluetooth is
limited in speed and range,Wi-Fi Direct is limited in speed and connectivity for medium
and large scenarios, and WiFi-Aware is a new and untested technology, whose specification
does not cover large scenarios.
In this thesis, we address this problem by presenting two communication topologies
and a network formation algorithm that enable the use of Wi-Fi Direct communication
between off-the-shelf mobile devices in medium and large scale scenarios. The communication
topologies, named Group-Owner Client-Relay Group-Owner and Group-Owner
Group-Owner, allow for Wi-Fi Direct intergroup communication, whilst the network
formation algorithm, named RedMesh, systematically creates networks of Wi-Fi Direct
groups. The algorithm proved to be very effective, achieving full connectivity in 97.28%
of the 1 250 tested scenarios.
The RedMesh algorithm distinguishes itself for being the first one to useWi-Fi Direct
communication topologies that can form tree and mesh structures, and for being the first
algorithm able to build networks that can rely only on unicast communication. We may
hence conclude that the work developed in this thesis makes significant progress in the
formation of large scale networks of off-the-shelf mobile devices
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