192 research outputs found
RTXP : A Localized Real-Time Mac-Routing Protocol for Wireless Sensor Networks
Protocols developed during the last years for Wireless Sensor Networks (WSNs)
are mainly focused on energy efficiency and autonomous mechanisms (e.g.
self-organization, self-configuration, etc). Nevertheless, with new WSN
applications, appear new QoS requirements such as time constraints. Real-time
applications require the packets to be delivered before a known time bound
which depends on the application requirements. We particularly focus on
applications which consist in alarms sent to the sink node. We propose
Real-Time X-layer Protocol (RTXP), a real-time communication protocol. To the
best of our knowledge, RTXP is the first MAC and routing real-time
communication protocol that is not centralized, but instead relies only on
local information. The solution is cross-layer (X-layer) because it allows to
control the delays due to MAC and Routing layers interactions. RTXP uses a
suited hop-count-based Virtual Coordinate System which allows deterministic
medium access and forwarder selection. In this paper we describe the protocol
mechanisms. We give theoretical bound on the end-to-end delay and the capacity
of the protocol. Intensive simulation results confirm the theoretical
predictions and allow to compare with a real-time centralized solution. RTXP is
also simulated under harsh radio channel, in this case the radio link
introduces probabilistic behavior. Nevertheless, we show that RTXP it performs
better than a non-deterministic solution. It thus advocates for the usefulness
of designing real-time (deterministic) protocols even for highly unreliable
networks such as WSNs
IEEE 802.15.4: a Federating Communication Protocol for Time-Sensitive Wireless Sensor Networks
Wireless Sensor Networks (WSNs) have been attracting increasing interests for developing a new
generation of embedded systems with great potential for many applications such as surveillance,
environment monitoring, emergency medical response and home automation. However, the
communication paradigms in WSNs differ from the ones attributed to traditional wireless networks,
triggering the need for new communication protocols. In this context, the recently standardised IEEE
802.15.4 protocol presents some potentially interesting features for deployment in wireless sensor
network applications, such as power-efficiency, timeliness guarantees and scalability. Nevertheless,
when addressing WSN applications with (soft/hard) timing requirements some inherent paradoxes
emerge, such as power-efficiency versus timeliness, triggering the need of engineering solutions for an
efficient deployment of IEEE 802.15.4 in WSNs. In this technical report, we will explore the most
relevant characteristics of the IEEE 802.15.4 protocol for wireless sensor networks and present the
most important challenges regarding time-sensitive WSN applications. We also provide some timing
performance and analysis of the IEEE 802.15.4 that unveil some directions for resolving the
previously mentioned paradoxes
A survey on wireless ad hoc networks
A wireless ad hoc network is a collection of wireless nodes that can dynamically self-organize into an arbitrary and temporary topology to form a network without necessarily using any pre-existing infrastructure. These characteristics make ad hoc networks well suited for military activities, emergency operations, and disaster recoveries.
Nevertheless, as electronic devices are getting smaller, cheaper, and more powerful, the mobile market is rapidly growing and, as a consequence, the need of seamlessly internetworking people and devices becomes mandatory. New wireless technologies enable easy deployment of commercial applications for ad hoc networks. The design of an ad hoc network has to take into account several interesting and difficult problems due to noisy, limited-range, and insecure wireless transmissions added to mobility and energy constraints. This paper presents an overview of issues related to medium access control (MAC), routing, and transport in wireless ad hoc networks and techniques proposed to improve the performance of protocols. Research activities and problems requiring further work are also presented. Finally, the paper presents a project concerning an ad hoc network to easily deploy Internet services on low-income habitations fostering digital inclusion8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI
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Design of energy efficient protocols-based optimisation algorithms for IoT networks
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe increased globalisation of information and communication technologies has transformed
the world into the internet of things (IoT), which is accomplished within the resources of
wireless sensor networks (WSNs). Therefore, the future IoT networks will consist of high
density of connected nodes that suffer from resource limitation, especially the energy one,
and distribute randomly in a harsh and large-scale areas. Accordingly, the contributions
in this thesis are focused on the development of energy efficient design protocols based
on optimisation algorithms, with consideration of the resource limitations, adaptability,
scalability, node density and random distribution of node density in the geographical area.
One MAC protocol and two routing protocols, with both a static and mobile sink, are
proposed.
The first proposed protocol is an energy efficient hybrid MAC protocol with dynamic
sleep/wake-up extension to the IEEE 802.15.4 MAC, namely, HSW-802.15.4. The model
automates the network by enabling it to work
exibly in low and high-density networks
with a lower number of collisions. A frame structure that offers an enhanced exploitation
for the TDMA time slots (TDMAslots) is provided. To implement these enhanced slots
exploitation, this hybrid protocol rst schedules the TDMAsslots, and then allocates each
slot to a group of devices. A three-dimensional Markov chain is developed to display the
proposed model in a theoretical manner. Simulation results show an enhancement in the
energy conservation by 40% - 60% in comparison to the IEEE 802.15.4 MAC protocol.
Secondly, an efficient centralised clustering-based whale optimisation algorithm (CC-
WOA) is suggested, which employs the concept of software de ned network (SDN) in its
mechanism. The cluster formulation process in this algorithm considers the random di-
versi cation of node density in the geographical area and involves both sensor resource
restrictions and the node density in the tness function. The results offer an efficient con-
servation of energy in comparison to other protocols. Another clustering algorithm, called
centralised load balancing clustering algorithm (C-LBCA), is also developed that uses par-
ticle swarm optimisation (PSO) and presents robust load-balancing for data gathering in
IoT.
However, in large scale networks, the nodes, especially the cluster heads (CHs), suffer
from a higher energy exhaustion. Hence, in this thesis, a centralised load balanced and scheduling protocol is proposed utilising optimisation algorithms for large scale IoT net-
works, named, optimised mobile sink based load balancing (OMS-LB). This model connects
the impact of the Optimal Path for the MS (MSOpath) determination and the adjustable
set of data aggregation points (SDG) with the cluster formulation process to de ne an op-
timised routing protocol suitable for large scale networks. Simulation results display an
improvement in the network lifespan of up to 54% over the other approaches
WiFly: experimenting with Wireless Sensor Networks and Virtual coordinates
Experimentation is important when designing communication protocols for
Wireless Sensor Networks. Lower-layers have a major impact on upper-layer
performance, and the complexity of the phenomena can not be entirely captured
by analysis or simulation. In this report, we go through the complete process,
from designing an energy-efficient self-organizing communication architecture
(MAC, routing and application layers) to real-life experimentation roll-outs.
The presented communication architecture includes a MAC protocol which avoids
building and maintaining neighborhood tables, and a geographically-inspired
routing protocol over virtual coordinates. The application consists of a mobile
sink interrogating a wireless sensor network based on the requests issued by a
disconnected base station. After the design process of this architecture, we
verify it functions correctly by simulation, and we perform a temporal
verification. This study is needed to calculate the maximum speed the mobile
sink can take. We detail the implementation, and the results of the off-site
experimentation (energy consumption at PHY layer, collision probability at MAC
layer, and routing). Finally, we report on the real-world deployment where we
have mounted the mobile sink node on a radio-controlled airplane
Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey
Wireless sensor networks (WSNs) consist of autonomous and resource-limited
devices. The devices cooperate to monitor one or more physical phenomena within
an area of interest. WSNs operate as stochastic systems because of randomness
in the monitored environments. For long service time and low maintenance cost,
WSNs require adaptive and robust methods to address data exchange, topology
formulation, resource and power optimization, sensing coverage and object
detection, and security challenges. In these problems, sensor nodes are to make
optimized decisions from a set of accessible strategies to achieve design
goals. This survey reviews numerous applications of the Markov decision process
(MDP) framework, a powerful decision-making tool to develop adaptive algorithms
and protocols for WSNs. Furthermore, various solution methods are discussed and
compared to serve as a guide for using MDPs in WSNs
Bandwidth Estimation for IEEE 802.11-based Ad Hoc Networks
International audienceSince 2005, IEEE 802.11-based networks have been able to provide a certain level of quality of service (QoS) by the means of service differentiation, due to the IEEE 802.11e amendment. However, no mechanism or method has been standardized to accurately evaluate the amount of resources remaining on a given channel. Such an evaluation would, however, be a good asset for bandwidth-constrained applications. In multihop ad hoc networks, such evaluation becomes even more difficult. Consequently, despite the various contributions around this research topic, the estimation of the available bandwidth still represents one of the main issues in this field. In this paper, we propose an improved mechanism to estimate the available bandwidth in IEEE 802.11-based ad hoc networks. Through simulations, we compare the accuracy of the estimation we propose to the estimation performed by other state-of-the-art QoS protocols, BRuIT, AAC, and QoS-AODV
An Energy Aware and Secure MAC Protocol for Tackling Denial of Sleep Attacks in Wireless Sensor Networks
Wireless sensor networks which form part of the core for the Internet of Things consist of resource constrained sensors that are usually powered by batteries. Therefore, careful
energy awareness is essential when working with these devices.
Indeed,the introduction of security techniques such as authentication and encryption, to ensure confidentiality and integrity of data, can place higher energy load on the sensors. However, the absence of security protection c ould give room for energy drain attacks such as denial of sleep attacks which have a higher negative impact on the life span ( of the sensors than the presence of security features.
This thesis, therefore, focuses on tackling denial of sleep attacks from two perspectives A security perspective and an energy efficiency perspective. The security perspective involves evaluating and ranking a number of security based techniques to curbing denial of sleep attacks. The energy efficiency perspective, on the other hand, involves exploring duty cycling and simulating three Media Access Control ( protocols Sensor MAC, Timeout MAC andTunableMAC under different network sizes and measuring different parameters such as the Received Signal Strength RSSI) and Link Quality Indicator ( Transmit power, throughput and energy efficiency Duty cycling happens to be one of the major techniques for conserving energy in wireless sensor networks and this research aims to answer questions with regards to the effect of duty cycles on the energy efficiency as well as the throughput of three duty cycle protocols Sensor MAC ( Timeout MAC ( and TunableMAC in addition to creating a novel MAC protocol that is also more resilient to denial of sleep a ttacks than existing protocols.
The main contributions to knowledge from this thesis are the developed framework used for evaluation of existing denial of sleep attack solutions and the algorithms which fuel the other contribution to knowledge a newly developed protocol tested on the Castalia Simulator on the OMNET++ platform. The new protocol has been compared with existing protocols and
has been found to have significant improvement in energy efficiency and also better resilience to denial of sleep at tacks Part of this research has been published Two conference
publications in IEEE Explore and one workshop paper
Formal QoS Validation Approach on a Real-Time MAC Protocol for Wireless Sensor Networks
Several wireless sensor network applications are currently popping up, in various domains. Their goal is often to monitor a geographic area. When a sensor detects a monitored event, it informs a sink node using alarm messages. The area surveillance application needs to react to such an event with a finite, bounded and known delay: these are real-time constraints. The network being linear, routing becomes unnecessary. This work proposes a new real-time MAC protocol with realistic assumptions on sensor networks. We present a formal validation of this protocol, and explicit the worst case times for the services offered by the protocol (initialization and alarm transmission using different modes)
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