Aldri Santos

Transmission power control techniques for wireless sensor networks

Communication is usually the most energy-consuming event in Wireless Sensor Networks (WSNs). One way to significantly reduce energy consumption is applying transmission power control (TPC) techniques to dynamically adjust the transmission power. This article presents two new TPC techniques for WSNs. The experimental evaluation compares the performance of the TCP techniques with B-MAC, the standard MAC protocol of the Mica 2 platform. These experiments take into account different distances among nodes, concurrent transmissions and node mobility. The new transmission power control techniques decrease energy consumption by up to 57% over B-MAC while maintaining the reliability of the channel. Under a low mobility scenario, the proposed protocols delivered up to 95% of the packets, showing that such methods are able to cope with node movement. We also show that the contention caused by higher transmission levels might be lower than analytical models suggest, due to the action of the capture effect.

Transmission power control in MAC protocols for wireless sensor networks

Medium access control (MAC) protocols manage energy consumption on the network element during communication, which is the most energy-consuming event on Wireless Sensor Networks (WSNs). One method to mitigate energy consumption is to adjust transmission power. This paper presents two approaches to adjust transmission power in WSNs. The first approach employs dynamic adjustments by exchange of information among nodes, and the second one calculates the ideal transmission power according to signal attenuation in the link. The proposed algorithms were implemented and evaluated with experiments, comparing their results with B-MAC, the standard MAC protocol in the Mica Motes 2 platform. Results show that transmission power control is an effective method to decrease energy consumption, and incurs in a negligible loss in packet delivery rates. For node distances of 5m, the proposed transmission power control techniques decrease energy consumption by 27% over B-MAC.

A beaconless Opportunistic Routing based on a cross-layer approach for efficient video dissemination in mobile multimedia IoT applications

Mobile multimedia networks are enlarging the Internet of Things (IoT) portfolio with a huge number of multimedia services for different applications. Those services run on dynamic topologies due to device mobility or failures and wireless channel impairments, such as mobile robots or Unmanned Aerial Vehicle (UAV) environments for rescue or surveillance missions. In those scenarios, beaconless Opportunistic Routing (OR) allows increasing the robustness of systems for supporting routing decisions in a completely distributed manner. Moreover, the addition of a cross-layer scheme enhances the benefits of a beaconless OR, and also enables multimedia dissemination with Quality of Experience (QoE) support. However, existing beaconless OR approaches do not support a reliable and efficient cross-layer scheme to enable effective multimedia transmission under topology changes, increasing the packet loss rate, and thus reducing the video quality level based on the user’s experience. This article proposes a Link quality and Geographical beaconless OR protocol for efficient video dissemination for mobile multimedia IoT, called LinGO. This protocol relies on a beaconless OR approach and uses multiple metrics for routing decisions, including link quality, geographic location, and energy. A QoE/video-aware optimisation scheme allows increasing the packet delivery rate in presence of links errors, by adding redundant video packets based on the frame importance from the human’s point-of-view. Simulation results show that LinGO delivers live video flows with QoE support and robustness in mobile and dynamic topologies, as needed in future IoT environments.

A Knowledge Plane for Autonomic Context-Aware Wireless Mobile Ad Hoc Networks

Due to the emergence of multimedia context-rich applications and services over wireless networks, networking protocols and services are becoming more and more integrated, thus relying on context and application information to operate. Further, wireless protocols and services have employed information from several network layers and the environment, breaking the layering paradigm. In order to cope with this increasing reliance on knowledge, we propose MANKOP, a middleware for MANETs that instantiates a new networking plane. The Knowledge Plane(KP) is a distributed entity that stores and disseminates information concerning the network, its services and the environment, orchestrating the collaboration among cross-layer protocols, autonomic management solutions and context-aware services. We use MANKOP to support the autonomic reconfiguration of a P2P network over MANETs. Simulation results show that the MANKOP-enabled solution is applicable to more scenarios than the classic approaches, as the network adapts its query dissemination strategy to match the current conditions of the peers.

A Security Management Architecture for Supporting Routing Services on WANETs

Due to the raising dependence of people on critical applications and wireless networks, high level of reliability, security and availability is claimed to assure secure and reliable service operation. Wireless ad hoc networks (WANETs) experience serious security issues even when solutions employ preventive or reactive security mechanisms. In order to support both network operations and security requirements of critical applications, we present SAMNAR, a Survivable Ad hoc and Mesh Network ARchitecture. Its goal lies in managing adaptively preventive, reactive and tolerant security mechanisms to provide essential services even under attacks, intrusions or failures. We use SAMNAR to design a path selection scheme for WANET routing. The evaluation of this path selection scheme considers scenarios using urban mesh network mobility with urban propagation models, and also random way point mobility with two-ray ground propagation models. Results show the survivability achieved on routing service under different conditions and attacks.

Detection of sinkhole attacks for supporting secure routing on 6LoWPAN for Internet of Things

The Internet of Things (IoT) networks are vulnerable to various kinds of attacks, being the sinkhole attack one of the most destructive since it prevents communication among network devices. In general, existing solutions are not effective to provide protection and security against attacks sinkhole on IoT, and they also introduce high consumption of resources de memory, storage and processing. Further, they do not consider the impact of device mobility, which in essential in urban scenarios, like smart cities. This paper proposes an intrusion detection system, called INTI (Intrusion detection of SiNkhole attacks on 6LoWPAN for InterneT of ThIngs), to identify sinkhole attacks on the routing services in IoT. Moreover, INTI aims to mitigate adverse effects found in IDS that disturb its performance, like false positive and negative, as well as the high resource cost. The system combines watchdog, reputation and trust strategies for detection of attackers by analyzing the behavior of devices. Results show the INTI performance and its effectiveness in terms of attack detection rate, number of false positives and false negatives.

Opportunistic routing for multi-flow video dissemination over Flying Ad-Hoc Networks

A reliable and robust routing service for Flying Ad-Hoc Networks (FANETs) must be able to adapt to topology changes. User experience on watching live video sequences must also be satisfactory even in scenarios with buffer overflow and high packet loss ratio. In this paper, we introduce a Cross-layer Link quality and Geographical-aware beaconless opportunistic routing protocol (XLinGO). It enhances the transmission of simultaneous multiple video flows over FANETs by creating and keeping reliable persistent multi-hop routes. XLinGO considers a set of cross-layer and human-related information for routing decisions, as performance metrics and Quality of Experience (QoE). Performance evaluation shows that XLinGO achieves multimedia dissemination with QoE support and robustness in a multi-hop, multi-flow, and mobile network environments.

QoE-driven dissemination of real-time videos over vehicular networks

Live video dissemination over Vehicular Ad Hoc Networks (VANETs) is fundamental for several services, e.g., roadside video emergency, advertisements broadcast, and smart video surveillance. All these applications face many challenges due to stringent video quality level requirements, dynamic topologies, and broadcast environments. To cope with these challenges, as well as reduce network routing overhead, geographic Statistical Routing Protocols (SRPs) have been proposed as a suitable solution for the distribution of video flows in VANETs, usually by using positioning and Quality of Service (QoS) parameters. However, rather than only these parameters, a satisfactory video dissemination from the users perspective also requires video and human-awareness issues. In real situations, due to different requirements and hierarchical structures of multimedia applications, network level and position parameters alone are not enough to select the best relay nodes and build up reliable backbones to multi-hop video dissemination with satisfactory reachability and Quality of Experience (QoE) levels. This article focuses on improving the disseminated quality of on-road live videos in VANETs. Thus, we propose the cross-layer QOe-driven REceiver-based (QORE) mechanism, which is modularly coupled to SRPs to offer QoE-aware and video-related parameters for the relay node selection and backbone maintenance. Thus, nodes decide for themselves to retransmit further the video sequences, enhancing the capacity of the system in delivering videos with better QoE assurance. On top of this, an application-level Error-Control (EC) scheme, namely Interleaving, allows mitigating the effects of frame loss by spreading out the bursty losses. We added QORE to a straightforward SRP built using the Distance method, named DQORE protocol. Results show the gains of DQORE compared to SRPs, achieving video dissemination with QoE support, less routing overhead, and satisfactory reachability, in V2V topologies.

A rule-based adaptive routing protocol for continuous data dissemination in WSNs

Wireless sensor networks (WSNs) are a subclass of ad hoc networks with severe resource constraints. These constraints preclude the use of traditional ad hoc protocols, and demand optimizations that incur in solutions specific to a class of applications. This work presents PROC, a protocol designed for continuous data dissemination networks that interacts with the application to establish routes. This mechanism allows the application to reconfigure PROC on runtime. PROC also provides fault-tolerance mechanisms to ensure reliable routes. A performance evaluation in topologies varying from 50 to 200 nodes showed that PROC increases network lifetime around 7% to 12%, and has a higher throughput than both energy-aware data-centric routing (EAD) and a simplified version of TinyOS Beaconing. Furthermore, PROC presents a graceful performance degradation when the number of nodes in the network increases.

Firefly-inspired and robust time synchronization for cognitive radio ad hoc networks

Harnessing the full power of the paradigm-shifting cognitive radio ad hoc networks (CRAHNs) hinges on solving the problem of time synchronization between the radios on the different stages of the cognitive radio cycle. The dynamic network topology, the temporal and spatial variations in spectrum availability, and the distributed multi-hop architecture of CRAHNs mandate novel solutions to achieve time synchronization and efficiently support spectrum sensing, access, decision and mobility. In this article, we advance this research agenda by proposing the novel Bio-inspired time SynChronization protocol for CRAHNs (BSynC). The protocol draws on the spontaneous firefly synchronization observed in parts of Southeast Asia. The significance of BSynC lies in its capability of promoting symmetric time synchronization between pairs of network nodes independent of the network topology or a predefined sequence for synchronization. It enables the nodes in CRAHNs to efficiently synchronize in a decentralized manner, and it is also reliable to changes, faults and attacks. The findings suggest that BSynC improves convergence time, thereby favoring deployment in dynamic network scenarios.