Richard Werner Nelem Pazzi

Monitoring patients via a secure and mobile healthcare system

Patient monitoring provides flexible and powerful patient surveillance through wearable devices at any time and anywhere. The increasing feasibility and convenience of mobile healthcare has already introduced several significant challenges for healthcare providers, policy makers, hospitals, and patients. A major challenge is to provide round-the-clock healthcare services to those patients who require it via wearable wireless medical devices. Furthermore, many patients have privacy concerns when it comes to releasing their personal information over open wireless channels. As a consequence, one of the most important and challenging issues that healthcare providers must deal with is how to secure the personal information of patients and to eliminate their privacy concerns. In this article we present several techniques that can be used to monitor patients effectively and enhance the functionality of telemedicine systems, and discuss how current secure strategies can impede the attacks faced by wireless communications in healthcare systems and improve the security of mobile healthcare.

Fault-tolerant wireless sensor network routing protocols for the supervision of context-aware physical environments

Applications that require fine-grain monitoring of physical environments subjected to critical conditions, such as fire, leaking of toxic gases and explosions, pose a great challenge to sensor network protocols. These networks have to provide a fast, reliable, fault-tolerant and energy-aware channel for events diffusion, which meets the requirements of query-based, event-driven and periodic sensor networks application scenarios. These requirements have to be met even in the presence of emergency conditions that can lead to node failures and path disruption to the sink. This paper proposes two routing protocols: periodic, event-driven and query-based protocol (PEQ) and its variation CPEQ, two fault-tolerant and low-latency algorithms that meet sensor network requirements for critical conditions supervision in context-aware physical environments. While PEQ can provide low latency for event notification, fast broken path reconfiguration, and high reliability in the delivery of event packets for low-network data traffic, CPEQ is a cluster-based routing protocol that groups sensor nodes to efficiently relay the sensed data to the sink by uniformly distributing energy dissipation among the nodes and reducing latency for high-network data traffic (typical in emergency situations). PEQ and its variant CPEQ use the publish/subscribe paradigm to disseminate requests across the network. We discuss both PEQ and CPEQ protocols, their implementation, and report on the performance results of several scenarios using NS-2 simulator. The results obtained are compared with the well-known directed diffusion (DD) protocol, and show that our proposed algorithms exhibit a clear indication to meet the constraints and requirements of critical condition supervision in context-aware physical environments. Our results indicate that PEQ outperforms DD in the average delay since it uses the shortest path for the delivery of packets and speed up new subscriptions by using the reverse path used for event notification packets. CPEQ also outperforms DD in both the average delay and in the packet delivery ratio when the network scales up.

A novel multi-hop clustering scheme for vehicular ad-hoc networks

Vast applications introduced by Vehicular Ad-Hoc Networks (VANETs), such as intelligent transportation, roadside advertisement, make VANETs become an important component of metropolitan area networks. In VANETs, mobile nodes are vehicles which are equipped with wireless antennas; and they can communicate with each others by wireless communication on ad-hoc mode or infrastructure mode. Compared with Mobile Ad-Hoc Networks, VANETs have some inherent characteristic, such as high speed, sufficient energy, etc. According to previous research, clustering vehicles into different groups can introduce many advantages for VANETs. However, because a VANET is a high dynamic scenario, it is hard to find a solution to divide vehicles into stable clusters. In this paper, a novel multi-hop clustering scheme is presented to establish stable vehicle groups. To construct multi-hop clusters, a new mobility metric is introduced to represent relative mobility between vehicles in multi-hop distance. Extensive simulation experiments are run using ns2 to demonstrate the performance of our clustering scheme. To test the clustering scheme under different scenarios, both the Manhattan mobility model and the freeway mobility model are used to generate the movement paths for vehicles.

DRIVE: An efficient and robust data dissemination protocol for highway and urban vehicular ad hoc networks

Abstract Vehicular Ad hoc Networks (VANETs) are an emerging technology that allows vehicles to form self-organized networks without the need of permanent infrastructure. VANETs have attracted the attention of the research community recently as they have opened up a myriad of on the road applications and increased their potential by providing intelligent transport systems. The envisaged applications, as well as some inherent VANET characteristics make data dissemination an essential service and a challenging task in these networks. Many data dissemination protocols have been proposed in the literature. However, most of these protocols were designed to operate exclusively in urban or highway scenarios and under dense or sparse networks. In addition, the existing solutions for data dissemination do not effectively address broadcast storm and network partition problems simultaneously. To tackle these problems, we propose a novel Data dissemination pRotocol In VEhicular networks (DRIVE) that relies exclusively on local one-hop neighbor information to deliver messages under dense and sparse networks. In dense scenarios, DRIVE selects vehicles inside a sweet spot to rebroadcast messages to further vehicles. Moreover, the protocol employs implicit acknowledgements to guarantee robustness in message delivery under sparse scenarios. DRIVE eliminates the broadcast storm problem and maximizes data dissemination capabilities across network partitions with short delays and low overhead. Simulation results show that DRIVE performs data dissemination with better efficiency than other algorithms, outperforming them in different scenarios in all the evaluations carried out.

HPEQ A Hierarchical Periodic, Event-driven and Query-based Wireless Sensor Network Protocol

Applications that require fine-grain monitoring of physical environments subjected to critical conditions, such as fire, leaking of toxic gases and explosions, pose a great challenge to sensor network protocols. These networks have to provide a fast, reliable, fault tolerant and energy aware channel for events diffusion, which meets the requirements of query-based, event-driven and periodic sensor networks application scenarios. These requirements have to be met even in the presence of emergency conditions that can lead to node failures and path disruption to the sink. This paper presents HPEQ (hierarchical periodic, event-driven and query-based), a cluster-based routing protocol that groups sensor nodes to efficiently relay the sensed data to the sink. In HPEQ protocol nodes with more residual energy are selected as aggregator nodes that relay data to the sink by uniformly distributing energy dissipation among the nodes, and reducing latency and network data traffic. HPEQ is based on a previous protocol, PEQ, that meets sensor networks requirements for critical conditions surveillance applications. HPEQ uses the publish/subscribe paradigm to disseminate requests across the network. The algorithm was implemented using NS-2 simulator and compared to PEQ and to the directed diffusion paradigm. Important metrics were evaluated showing that the proposed algorithm can be a potential solution to meet constraints and requirements of events delivery in critical conditions monitoring applications

Mobile data collector strategy for delay-sensitive applications over wireless sensor networks

Applications that require fast response time such as emergency preparedness and hostile environment surveillance pose challenging obstacles to wireless sensor network (WSN) protocols. A routing protocol must provide fast and reliable techniques for data propagation. Most routing solutions for WSNs utilize static sinks to collect data from the entire network. This approach results in high traffic load in the sinks vicinity. The nodes located near the sink will be more requested than other nodes in the network. Therefore, these nodes will consume more energy and face high congestion in a large scale network. In this paper, we propose a solution to the problem of deploying mobile data collectors in order to alleviate the high traffic load and resulting bottleneck in a sinks vicinity caused by static approaches. Our proposed MDC/PEQ protocol employs mobile data collectors (MDCs) that broadcast beacons periodically. Sensor nodes that receive the beacon will join the MDCs cluster and update their routing information in order relay data packets to the MDC. Sensor nodes use the signal strength of the beacon in order to perform a simple but efficient route re-configuration (handoff). An extensive set of simulation experiments is conducted and results confirm that the introduction of mobile data collectors in wireless sensor networks reduces the bottleneck at the nodes closer to the sink. Our proposed mobility technique for data gathering introduces no traffic or energy overhead. In fact, it significantly reduces traffic and, consequently, packet delay and energy dissipation by reducing the average number of hops that data packets traverse from source sensor nodes to sinks or mobile data collectors.

Design and Evaluation of Context-Aware and Location-Based Service Discovery Protocols for Vehicular Networks

The increasing number of potential applications related to intelligent transportation systems (ITSs) have attracted researchers to the area of vehicular networks (VNs). Two main classes of applications have lately gained popularity, i.e., security and safety, and traffic information and service location applications. However, several open research challenges are delaying the efficient and widespread deployment and management of such applications in VNs. One of these challenges comprises how vehicles and service providers could discover each other in VNs, which are well known for their large scale and high mobility. Most service discovery strategies available present high overhead and poor performance in a VN environment. Existing context-aware and location-based service discovery protocols (LocVSDPs) are either designed without considering the particularities of VNs or are not scalable with the increase in network density and the number of requests. In this paper, we propose a new context-aware and LocVSDP (EB-LocVSDP) for VNs and its variant (Naive-LocVSDP). Our protocols offer a scalable framework for the discovery of time-sensitive and location-based services in VNs. They rely on a cluster-based infrastructure. Furthermore, LocVSDPs are integrated into the network layer and use channel diversity to improve service discovery efficiency. We discuss the implementation of our protocols and techniques, report on performance evaluation experiments, and offer a comparison against an existing location-based discovery protocol [the Vehicular Information Transfer Protocol (VITP)]. Our simulation results indicate that our proposed LocVSDPs show a gain of 20% in terms of success rate. LocVSDPs use at least 90% less bandwidth than VITP, and their average response time is at least 10% lower than VITP for successful query transactions.

Remote rendering and streaming of progressive panoramas for mobile devices

Providing mobile devices with virtual environment walkthrough and real-time streaming movie playback capability is expected to have a profound impact to the entertainment-based applications, such as virtual guides, online gaming, and e-learning, just to name a few. However, it is well known that it is extremely difficult to render complex 3D scenes at interactive frame rates on thin mobile devices known for their lack of proper resources needed to process large volume of 3D virtual environment data. In order to provide virtual environment navigation on thin mobile clients, we propose a hybrid technique which combines both remote geometry rendering and streaming of warped images. In our approach, the server renders a partial panoramic view, which is based on the users viewpoint and last movements. The server then warps the images coordinates into cylindrical coordinates, and streams the images to the client device, which will progressively build the panoramic representation of the scene. Furthermore, in order to enhance streaming performance and quality of the interaction, we propose to use a rate control mechanism as well as a prediction of the users movements within the virtual scene. In this paper we discuss our scheme for remote rendering and streaming of progressive panoramas for mobile devices, and present our experimental results we have obtained in order to validate our proposed technique. Our results indicate clearly that the proposed solution is able to achieve stable frame rates and throughput in error-prone wireless channels.

An end-to-end virtual environment streaming technique for thin mobile devices over heterogeneous networks

Advances in mobile computing devices have resulted in a new class of 3D virtual environment applications such as virtual guides and malls, online gaming, training and monitoring systems, just to name a few. The challenge lies in determining how to provide a rich and detailed 3D virtual environment to these thin devices, since they are known for their lack of the proper resources required to process large scale 3D geometric data. In a wireless scenario, in which bandwidth is highly dynamic, users may experience long delays when downloading an entire 3D environment before they start interacting with it. Furthermore, thin wireless mobile devices are unable to handle the complexity of 3D graphics at interactive frame rates. In this research work, we propose efficient end-to-end streaming and rate control protocols. Our approach consists of moving the demanding geometry-rendering task to a dedicated remote rendering server that streams the rendering output to a client, leaving only the displaying and certain minor image-based rendering tasks to the local, less powerful mobile hardware. We also investigate an image buffer management mechanism in order to deal with the small storage available on thin devices. We discuss the design of our proposed solutions and report on their performance evaluation through an extensive set of simulation experiments.

An inter-cluster communication based energy aware and fault tolerant protocol for wireless sensor networks

The ambient intelligence paradigm is built upon Ubiquitous Computing (UC), in which the computing devices are embedded in the environment with the purpose of enhancing the human experience at home, workplace/office, learning, health care etc. The UC applications aim at providing services to the users anywhere, anytime in an unobtrusive, seemingly invisible way. Wireless sensor networks (WSNs) have great potential for UC applications and are envisioned to revolutionize them. This paper presents a clustering routing protocol for event-driven, query-based and periodic WSNs. The protocol aims at optimizing energy dissipation in the network as well as providing network’s fault tolerance and connectivity. Message propagation is accomplished by using short distance transmissions by employing nearest neighbor nodes between neighboring clusters. Moreover, the algorithm proposes using an energy efficient approach by alternating the nodes responsible for inter-cluster communication inside one cluster. The algorithm also aims at even energy dissipation among the nodes in the network by alternating the possible routes to the Sink. This helps to balance the load on sensor nodes and increases the network lifetime, while avoiding congested links at the same time. We discuss the implementation of our protocol, present its proof of correctness as well as the performance evaluation through an extensive set of simulation experiments.