Luiz Henrique A. Correia

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.

Transmission power control techniques for MAC protocols in wireless sensor networks

Communication is usually the most energy - consuming event in wireless sensor networks (WSNs). The lifetime of these networks is determined by the capacity of batteries and one of the biggest challenges is to reduce the energy consumed in the communication. Several techniques to reduce the energy consumption have been proposed in routing protocols: diminish the traffic of data, optimize the routes or the control of the topology. However, the management and operation of the nodes radio is responsibility of the medium access control (MAC) protocol. This thesis presents four new transmission power control (TPC) techniques for MAC protocols in WSNs. These techniques are based on the interaction between sensor nodes and take into account the limitations of resources such as processing, memory and energy in the calculation of the minimum of transmission power. To evaluate these techniques, four MAC protocols had been developed: iterative, attenuation, AEWMA and hybrid. The Iterative was the first MAC protocol with TPC developed exclusively for WSN. These protocols have been experimented in the Mica Motes2 platform, in diverse scenarios varying parameters such as internal and external environment, the distance among the communicating nodes, the occurrence of simultaneous transmissions, the use of multi-hop transmissions and node mobility. Results have shown that TPC protocols reduce the energy consumption by up to 57% in comparison to the protocols with fixed transmission power. Moreover, the protocols with TPC increase the throughput of the network while maintaining a very high delivery rate.

A pro-active routing protocol for continuous data dissemination in wireless sensor networks

Wireless sensor networks are 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 article presents PROC, a protocol designed for continuous data dissemination networks, that interacts with the application to establish routes, allowing the application to reconfigure PROC on runtime. A performance evaluation in topologies varying from 50 to 200 nodes showed that PROC increases network lifetime around 7% to 12%, and has higher throughput than EAD and TinyOS Beaconing. Furthermore, PROC presents a softer performance degradation when the number of nodes in the network increases.

DynMAC: A resistant MAC protocol to coexistence in wireless sensor networks

Abstract The growth of mobile and ubiquitous computing has increased the demand for wireless communications, which in turn raises interference levels and spectrum pollution, causing problems of network coexistence. The coexistence assurance between these devices and wireless sensor networks is a big challenge. This paper proposes a new medium access protocol, DynMAC (Dynamic MAC), which uses mechanisms of dynamic channel reconfiguration, recovery from lost links and reconfiguration of transmission parameters based on the properties of the cognitive radios, to deal with this problem. Simulations and experiments using a real WSN testbed, were performed to validate our protocol. Results show that the proposed mechanisms solve the WSN configuration problems, in noisy and interference environments, and enable the coexistence with different networks and devices operating in the same frequency spectrum, while maintaining application requirements in critical deployment scenarios.

A framework for cognitive radio wireless sensor networks

The growth of mobile computing has increased the demand for wireless communication, causing a higher demand for the wireless medium as well as spectrum pollution. Smart radios, also called cognitive radios, monitor the network to identify the best available channel, in order to avoid interference. This paper proposes a framework for the development and testing of protocols for wireless sensor networks that employ cognitive radios (CRSN). We also developed two spectrum decision protocols for CRSN, which provide distributed mechanisms to select the best wireless channel based on the applications QoS requirements. Simulations of low, medium and high noise scenarios have shown that the protocols improve the delivery rate by up to 69%, while keeping the delay and energy consumption unaltered.

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.

Evaluating Fault Tolerance Aspects in Routing Protocols for Wireless Sensor Networks

Fault tolerance is an essential requirement in the design of protocols and applications for Wireless Sensor Networks (WSNs) since communication and hardware failures are frequent. In this paper we studied the resilience of routing protocols for continuous data dissemination WSNs in face of faults. The main causes of silent failure are presented and classified, including security attacks. An evaluation of routing protocols shows that failures under a large region of the network are the most damaging. We also show how routing protocols may save energy by temporarily turning off disconnected nodes.

Transmission power and data rate aware routing on wireless networks

Wireless networks can vary both the transmission power and modulation of links. Existing routing protocols do not take transmission power control (TPC) and modulation adaptation (also known as rate adaptation - RA) into account at the same time, even though the performance of wireless networks can be significantly improved when routing algorithms use link characteristics to build their routes. This article proposes and evaluates extensions to routing protocols to cope with TPC and RA. The enhancements can be applied to any link state or distance vector routing protocols. An evaluation considering node density, node mobility and link error show that TPC- and RA-aware routing algorithms improve the average latency and the end-to-end throughput, while consuming less energy than traditional protocols.

A taxonomy for medium access control protocols in wireless sensor networks

Wireless sensor networks (Wsns) tend to be highly optimized due to severely restricted constraints. Various medium access control (Mac) protocols forWsns have been proposed, being specially tailored to a target application. This paper proposes a taxonomy for the different mechanisms employed in those protocols. The taxonomy characterizes the protocols according to the methods implemented to handle energy consumption, quality of service and adaptability requirements. We also present an overview of the transceptors found inWsns, identifying how events on communication affect the energy consumption. Based on the taxonomy, we classify existingMac protocols. Finally, we discuss challenging trends inMac protocols forWsns, such as security issues and software radios.RésuméLe fonctionnement des réseaux de capteurs sans fil doit être particulièrement optimisé en raisons même des contraintes fortes qu’ils subissent. Plusieurs protocoles de contrôle d’accès au support (Mac) ont été proposés, le plus souvent adaptés à telle ou telle application. Cet article propose une taxinomie des différents mécanismes apparaissant dans ces protocoles en prenant comme critère la consommation d’énergie, la qualité de service et l’adaptation aux diverses contraintes. On présente également un panorama des émetteurs-récepteurs des réseaux de capteurs sans fil en précisant notamment les éléments de la communication qui affectent la consommation d’énergie. A partir de cette taxinomie, on présente une classification des protocolesMac existants. Enfin, on analyse quelques points clés de ces protocoles notamment les questions liées à la sécurité et la radio logicielle.