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Intelligent Transportation Systems (ITS) are attracting growing attention both in industry and academia due to the advances in wireless communication technologies, and a significant demand for a wide variety of applications targeting this kind of environments are expected. In order to make it usable in real vehicular environments, achieving a well-designed Medium Access Control (MAC) protocol is a...
There is a lack of reliable tools for evaluating the performance of Delay Tolerant Networks (DTN). Frequently, the researchers use small-scale real networks or one of the few available DTN simulators. This work presents an alternative approach for conducting performance evaluation studies of DTN, following a recent movement of the scientific community with respect to the use of hybrid environments...
Mission-critical surveillance applications such as intrusion detection or disaster response have vital requirement in QoS. We consider a Wireless Image Sensor Network (WISN) with a scheduling of image sensor node's activity based on the application criticality level. Sentry nodes capable of detecting intrusions with a higher probability than others will alert neighbor nodes as well as activating cover...
Critical monitoring applications can use wireless sensor networks to transport delay sensitive data. This data may demand bounded delays in order to be considered useful by the receiver. In these cases, an accurate and real-time estimation of the end-to-end delay could be used to anticipate the data usefulness prior to sending it. A novel real-time and end-to-end delay estimation mechanism is proposed...
We analyze next generation cellular networks, offering connectivity to mobile users through multiple radio access technologies (RATs), namely LTE and WiFi. We develop a framework based on the Markovian agent formalism, which can model several aspects of the system, including user traffic dynamics and radio resource allocation. In particular, through a mean-field solution, we show the ability of our...
With the increasing number of users subscribing to mobile Internet such as 3G and 4G networks, the Wireless Internet Services providers (WISP) aim to offer a good service for customers while elevating the number of clients. Several proposals to offload the traffic of 3G networks have been made in the past few years, including the use of femtocells,WiFi offloading and more recently mobile-to-mobile...
Cyber world and physical world were considered as two different entities in the past decade. However, researchers have found that these two entities are closely correlated with each other after integration of sensor/actuators in the cyber systems. Cyber systems became responsive to the physical world by enabling real time control emanating from conventional embedded systems, thus emerging a new research...
We present MultiFlow as a new approach for efficiently supporting IP Multicast traffic over IEEE 802.11 WLANs. In MultiFlow a multicast traffic flow is transparently converted to multiple unicast flows, one for each multicast subscriber, in the fixed part of the network behind wireless access points (APs). The conversion process is applied selectively on multicast traffic flows—based on the status...
WiFi Direct introduces new opportunities to deploy real opportunistic networks through users' mobile devices. However, its original specification does not take into account all the parameters that can emerge from an opportunistic network scenario, not only in terms of technical requirements (e.g., available resources and connectivities) but also of users characteristics and profiles, which can heavily...
The main desire of end-users of a telecommunication system is to take advantage of satisfactory services, in terms of Quality of Service (QoS), especially when they pay for a required needing. Unfortunately, when hosts are moving into an infrastructured network, it is very important to mitigate hand-over effects, which may cause heavy flow degradations or disruptions. In this paper, we are interested...
Cooperative relaying is gaining a significant attention in that, intermediate relay nodes assist the source nodes to enhance the overall network efficiency. In network coded cooperative communications, the relay node linearly combines the data received from the sources and forward the linear combination to the destination. In this paper, we present the maximum likelihood decoding scheme for a network...
Energy consumption is a critical point for sensor networks, which are located in remote places without access to the power grid and must harvest their own energy. The same networks may also have to use Delay Tolerant Networking technologies if they can't have a permanent connectivity. The PEAR routing algorithm was proposed to address the latter problem. In this paper, we propose an optimization of...
It is known that in indoor environments errors tend to happen in bursts, severely damaging the performance of upper layer protocols and, in particular, TCP. This work compares the performance of this protocol over two channel models (by means of simulation) that are able to replicate the presence of long error bursts: the first one is based on a Hidden Markov Process, while the second one uses an...
Current home networks are often split up in high data rate networks for multimedia and internet applications and low data rate networks for home automation. This separation leads to inefficient and cumbersome network configurations. It also hinders the widespread use of home automation networks. The IPv6 adaptation for resource constrained devices can help to realize a common addressing scheme for...
In this paper, a hybrid approach for Radio Access Technology (RAT) selection in heterogeneous wireless networks is proposed. This decision framework dynamically integrates operator objectives and user preferences, with a relatively reduced network complexity, signaling and processing load. By broadcasting cost and QoS parameters, the network assists mobile users in their decisions. Focusing on the...
In light of the growing disparity between residential broadband and 802.11 speeds, Access Point (AP) backhaul aggregation has been proposed by the research community as a service whereby residential customers may enjoy higher throughput when in range of participating 802.11 APs. The fundamental assumption of these works is that 802.11 clients can be modified at driver level. However, due to the high...
The purpose of this work is to evaluate the interference produced by LTE Femtocells operating at 700 MHz on Digital Television (SBTD) that, in Brazil, employs the Integrated System for Digital Broadcast, Brazilian Version (ISDB-Tb) standard. The study considered indoor interference from a 700 MHz Femtocell on the digital television channel located at 695 MHz. Experimental results were compared with...
This paper presents a systematic comparative study involving two fundamental mechanisms envisaged to play a crucial role in 4G networks, namely, fractional frequency reuse (FFR) and coordinated multipoint transmission (CoMP). A simulation framework is developed to assess the performance of the most relevant coordination schemes under different user scheduling policies while also revealing what are...
Video delivery over VANETs is a difficult task. On the one hand, video streaming is a demanding application, where big deals of data need to be processed and transmitted. On the other hand, VANETs are error prone networks due to the high mobility of the nodes and the wireless channel. The sum of these two factors makes video transmission a hard to manage task. In this paper we evaluate the new emerging...
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