1,721,030 research outputs found
Adaptive IEEE 802.15.4e LLDN scheduler for wireless network control systems
Get PDFAn active area of research in the automotive research community is the stability of
Long Commercial Vehicles (LCVs) using active trailer steering and/or braking. These
LCVs rely on sensor data located across different regions of the tractor and trailers and compose the LCV. Communication of the sensor data to the Electronic Control Unit (ECU) of the active trailer system is performed through a conventional wired bus. The benefits of wireless communication for an LCV are improved flexibility, maintenance, elimination of physical socket connections and, reduction of weight related to the wires in the vehicle. In LCVs there is a natural demarcation point between the tractor and trailers where wireless communications can replace the wired communication bus. This thesis investigates the latency and throughput of wireless communication using IEEE 802.15.4 and IEEE 802.15.4e Low Latency Deterministic Network (LLDN) protocols for different sensor sampling rates in an LCV scenario and creates a guidelines for the system designers to select the right sensor sampling times. Furthermore, it proposes a new adaptive IEEE 802.15.4e LLDN algorithm that computes the optimal timeslot and superframe duration based on the sensor node data inter-arrival times to achieve the desired LCV controller latency that will exhibit stable behaviour. Simulation results confirm that this adaptive IEEE 802.15.4e LLDN algorithm can configure the IEEE 802.15.4e LLDN that present the best results for delay as well maximum throughput for a desired latency.University of Ontario Institute of Technolog
User behavior pattern based security provisioning for distributed systems
Get PDFBehaviors of authorized users must be monitored and controlled due to the rise
of insider threats. Security analysts in large distributed systems are overwhelmed
by the number of system users, the complexity and changing nature of user activities.
Identifying user behavior patterns by analyzing audit logs is challenging.
Lacking a general user behavior pattern model restricts the effective usage of data
mining techniques. Limited access to real world audit logs due to privacy concerns
also blocks user behavior leaning. The central problem addressed in this thesis is
the need to assist security analysts obtain deep insight into user behavior patterns.
To address the research problem, the thesis defines a user behavior pattern
as consisting of four factors: actor, action sequence, context, and time interval.
Based on this behavior pattern model, the thesis proposes a knowledge-driven
user behavior pattern discovery approach, with step-by-step guidance for security
analysts throughout the whole process. The user behavior pattern mining process
are all uniformly represented using a formalism. A user/tool collaborative environment
on top of data mining techniques is designed for constructing a baseline
of common behavior patterns to individuals, peer groups, and specific contexts.
A prototype toolkit that is developed as part of this thesis provides an environment
for user behavior pattern mining and analysis. To evaluate the proposed
approach, a behavior-based dataset generator is developed to simulate audit logs
containing designed user behavior patterns. Moreover, two real world datasets
collected from distributed medical imaging systems and public cloud services are
respectively applied to test the proposed model.University of Ontario Institute of Technolog
Optimized multi-superframe scheduling for clustered wireless sensor networks
Get PDFSince the power source for wireless sensor networks (WSN) is mainly from batteries, prolonging network life is an important requirement of the network. Hence, clustering algorithms are employed to decrease the number of packets in the network via data aggregation as well to reduce packet network collisions by adopting scheduled communication among nodes in a cluster. The composition of the superframe plays an important role in scheduling the communication among the nodes in the network as well as determining the application data rate of acquisition. The differential evolution (DE) algorithm is used to fulfill the objective, to maximize network life under different data acquisition rate. The data acquisition rate is dependent on the IEEE 802.15.4e superframe. In addition, the multi-superframe structure is utilized to enable nodes to conserve more energy. The proposed method provides a set of solutions, based on the constraints and goals.University of Ontario Institute of Technolog
Distributed policy-based management framework for wireless sensor networks.
Get PDFPolicy-Based Management Systems (PBMS) are becoming a critical component of any information technology environment, due to their ability to abstract hardware complexity from their users. Policy-based systems exist in such areas as data center management, security, privacy, and computer network management. The Wireless Sensor Network (WSN) is no exception, although implementation of policy-based management in a WSN is still in its infancy. Wireless Sensor Networks (WSNs) are particularly challenging due to many characteristics, such as a working environment that makes maintenance and support a challenge; a deployment scale of hundreds, if not thousands, of nodes; and constrained hardware resources. Memory, processing, and battery power are limited, making WSNs capable of handling only applications with limited resource requirements. Consequently, the implementation of policy-based management applications on WSNs has to tackle these characteristics of WSNs and take these limitations into consideration during the design phase. Therefore, due to hardware resource constraints, policy-based management applications on WSNs can store only a limited number of policies in the local memory of a sensor node and must recycle them when additional policies are required. This recycling process creates communication overhead on the network and requires a policy deployment mechanism. The communication overhead will logically reduce the lifetime of the sensor's batteries, and the policy's deployment mechanism dictates system limitations and capabilities. To tackle these challenges, a new distributed policy-based management framework named TinyPolicy has been devised, which can store, locate, access, and execute any policy in the WSN. This new framework uses a newly created policy deployment mechanism named PolicyP2P, which is designed to make the distributed policy-based management system more robust against node failure, eliminate the threat of single points of failure, and improve policy availability. More importantly, it will increase the total number of policies that can be deployed in the WSN, which will result in more manageable constraints or tasks.University of Ontario Institute of Technolog
A directional preference ETX measure for the collection tree protocol in mobile sensor networks
Get PDFThere has been a growing interest in Wireless Sensor Networks (WSN) that utilizes mobile nodes for various purposes. These mobile wireless sensor networks tend to suffer from constant link breakages mainly caused by connected nodes moving apart, often moving very quickly. These lost connections require WSNs to constantly repair the network connections; this constant maintenance in turn causes power and packet losses and very noisy network conditions. However a performance extending metric can be implemented in order to reduce the frequency and occurrence of lost links between a parent node and its child. As such a directional preference Estimated Transmissions Count (ETX) measure was developed for the Collection Tree Protocol (CTP) in order to create longer lasting links. This thesis describes and measures the performance of this directional preference ETX measure utilizing various metrics such as Packet Reception Ratio, average number of beacon transmissions per node, Parent changes and various others. The Packet Reception Ratio metric is primarily used to compare this directional preference ETX measure to other popular WSN algorithms such as M-Leach, Geographic Greedy Forwarding and as well regular CTP due to the differences in topology between these algorithms. Based on the packet reception ratio the directional preference ETX measure improves the performance of CTP such that it is capable of outperforming M-Leach in various scenarios.University of Ontario Institute of Technolog
Energy aware scheduling using reinforcement learning for 802.15.4e Time-Slotted Channel Hopping
Get PDFTime Slotted Channel Hopping (TSCH) is a medium access control mode defined in IEEE 802.15.4e standard. This protocol is a crucial component of fourth-generation IoT applications, enabling efficient communication through synchronized time slots and channel hopping. By employing TSCH, IoT devices can achieve improved reliability, reduced interference, and increased network capacity. However, the energy consumption of IoT devices remains a significant challenge in large-scale deployments. This research introduces an energy-aware (EARL) schedule based on Reinforcement Learning (RL) for the 802.15.4e Time-Slotted Channel Hopping (TSCH) mode. The goal is to turn off slots in the 802.15.4e TSCH frame that are not highly utilized so as to conserve energy. By considering a predefined threshold, each node determines the slots that should be deactivated. This adaptive scheduling strategy allows the nodes to conserve energy effectively by minimizing unnecessary radio operations. Through extensive simulations and evaluations with simple and large-scale network configurations, the proposed energy-aware TSCH scheduling algorithm using Q-learning demonstrates promising results and is compared with the Orchestra protocol. This innovative approach reveals superior performance compared to Orchestra, achieving notably improved outcomes in both packet delivery rate and energy savings.University of Ontario Institute of Technolog
Integration of component-based frameworks with sensor modeling languages for the sensor web
Get PDFThe goal of this thesis is to develop an easily modifiable sensor system. To achieve this goal SensorML (an XML based sensor language) is combined with Java Beans (a component model language). An important part of SensorML is its process model. Each sensor in the real world is depicted in SensorML by a process model, whereas the connections between the sensors are shown by a process chain. This thesis presents a translator that reads these documents and converts them to Java Beans. Through testing the Translator is proved more efficient than the convenient Object Oriented approach.University of Ontario Institute of Technolog
QoS-aware energy efficient time-slotted channel schedule for heterogeneous IoT sensor networks
Get PDFThe emergence of the Internet of Things (IoT) has attracted significant attention in industrial environments, where applications must meet specified Quality of Service (QoS) requirements for latency, throughput, and packet loss. To address this, the IEEE 802.15.4e standard introduced the Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol. However, the protocol does not specify any particular MAC schedule. Designing a centralized scheduling system that simultaneously achieves the required QoS is challenging due to the multi-objective optimization nature of the problem. Additionally, managing the energy consumption of IoT devices is also crucial while achieving the QoS requirements of the sensing applications. This thesis presents a novel QoS-aware Energy Efficient optimized TSCH scheduling algorithm (QoE-TSCH), designed to meet QoS requirements such as delay and packet loss for multiple services within a heterogeneous sensor network, while also achieving the expected throughput. The QoE-TSCH algorithm incorporates a padding strategy to increase the duty cycle, resulting in reduced energy consumption. The QoE-TSCH algorithm was implemented in MATLAB and evaluated within a co-simulation environment that integrates both MATLAB and TSCH, focusing on a range of sensor network topologies and industrial QoS scenarios as defined by the ISA SP100 standard. The evaluation results indicate that the optimum schedules produced by the QoE-TSCH algorithm effectively support both “open-loop” and “monitoring” industrial services specified in the ISA SP100 standard for sensor networks comprising 16 to 36 nodes. While the delay requirements are met in scenarios involving 64 nodes, the packet loss rates in these cases exceed the maximum acceptable threshold by an average of 0.5%. Additionally, the algorithm’s energy-saving strategy significantly improves the scheduling duty cycle. The reduction in the duty cycle enhances energy efficiency across sensor network configurations ranging from 16 to 64 nodes. Specifically, for scenarios with 16 to 36 nodes, the duty cycle was reduced by approximately 80%, while for scenarios with 64 nodes, the reduction was around 15%
Access control obligation specification and enforcement using behavior pattern language
Get PDFIncreasing the use of Internet-based devices offers novel opportunities for users
to access and share resources anywhere and anytime so that such a collaborative
environment complicates the design of an accountable resource access control system.
Relying on only predefined access control policies based on an entity's attributes,
as in traditional access control solutions, cannot provide enough flexibility to apply
continuous adjustments in order to adapt to any kind of operative run time conditions.
The limited scope and precision of the existing policy-based access control solutions
have put considerable limitations on adequately satisfying the challenging security
aspects of the IT enterprises.
In this research, we focus on the obligatory behavior that can play an important
role in access control to protect resources and services of a typical system. Since
traditional access control is performed only once before the resource is accessed by
the subject, the access control system is unable to control the fulfillment of obligation
while the access is in progress. Practically, such a requirement is implemented in
hard-coded and proprietary ways. Consequently, the lack of sophisticated means
for specification and enforcement of obligation in access control system decreases its
flexibility and may also lead to the security breach in sensitive environments.
We provide a descriptive language that is capable of defining a variety of complex
behavior patterns based on a sequence of user actions. Such a description can be used
to specify different elements of the obligation in order to attach to a policy language,
and it is also used to generate queries for behavior matching purposes.
Moreover, we propose a behavior pattern matching framework to approve the
fulfillment of the obligation by looking into the audit logs. However, this method is
extremely inadequate for ongoing obligations. Therefore, we proposed a compliance
engine by utilizing complex event processing in order to make a decision to revoke
or continue the access in a timely manner. We implemented both frameworks that
can be used to approve the obligation fulfillment as well as to evaluate the expressive
power and complexity of our proposed language.University of Ontario Institute of Technolog
A wireless communication based active safety system for articulated heavy vehicles
Get PDFTo date, various active safety systems, have been developed to improve the safety of road vehicles. This dissertation presents a novel active trailer steering (ATS) system using wireless communication to exchange data among controllers and sensors allocated on the leading and trailing units of an articulated heavy vehicle (AHV). Conventionally, integrating the sensors, actuators, and controllers located on the leading and trailing units of the vehicle needs wired connections. The physical connection at the articulation joint increases the risk of disconnections and damages. Adopting a wireless communication system displays pronounced advantages, including flexibility, cost-effectiveness and ease of maintenance. For AHV's lateral stability control using wireless communication based ATS, addressing the problem of data delay and loss is the main challenge of this study. Innovative solutions have been proposed to tackle the challenges and numerical simulations have been conducted to evaluate the applicability and effectiveness of the proposed techniques for wireless communication based ATS. To this end, a realistic co-simulation platform is designed: the wireless communication based ATS system is constructed in MATLAB/Simulink; the virtual AHV is built in TruckSim; by means of integrating the ATS system and the virtual AHV, the co-simulation can be performed. As a preliminary design, a gain scheduler is introduced to compensate for the effect of data delay and stabilize the AHV. Later, in order to ensure the performance of the ATS control, a Kalman filter-based estimator is introduced. The estimator uses the available dynamic data to estimate the current states of the AHV in case some sensor data is not available. Several design parameters of the communication system based on dedicated short range communication (DSRC) standard such as modulation, quantization, channel estimation algorithm and transmit diversity have been studied. The effect of each parameter on AHV lateral stability is reviewed to propose proper configuration of the DSRC standard. Finally, an adaptive extended Kalman filter is introduced to mitigate the effects of asynchronous time delay on the AHV lateral stability. This thesis initiates the concept of wireless communication based ATS systems for AHVs and provides valuable guidance for such design and development.University of Ontario Institute of Technolog
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