Petros Spachos

Scalable Dynamic Routing Protocol for Cognitive Radio Sensor Networks

Wireless sensor networks (WSNs) have been increasingly considered an attractive solution for a plethora of applications. The low cost of sensor nodes provides a mean to deploy large sensor arrays in a variety of applications, such as civilian and environmental monitoring. Most of the WSNs operate in unlicensed spectrum bands, which have become overcrowded. As the number of the nodes that join the network increases, the need for energy-efficient, resource-constrained, and spectrum-efficient protocol also increases. Incorporating cognitive radio capability in sensor networks yields a promising networking paradigm, also known as cognitive radio sensor networks. In this paper, a cognitive networking with opportunistic routing protocol for WSNs is introduced. The objective of the proposed protocol is to improve the network performance after increasing network scalability. The performance of the proposed protocol is evaluated through simulations. An accurate channel model is built to evaluate the signal strength in different areas of a complex indoor environment. Then, a discrete event simulator is applied to examine the performance of the proposed protocol in comparison with two other routing protocols. Simulation results show that when comparing with other common routing protocols, the proposed protocol performs better with respect to throughput, packet delay, and total energy consumption.

Energy Aware Opportunistic Routing in Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have been increasingly considered an attractive solution for a plethora of applications, such as unattended event monitoring and tracking. Energy consumption is one of the looming challenges that threaten the successful deployment of these networks, especially when they are designed to operate unattended for long periods of time. In this paper, we are introducing an Energy-Aware Opportunistic Routing protocol (EAOR), for Wireless Sensor Networks, which keeps a balance between the Quality of Service (QoS) and the energy efficiency. The main objective is to maximize network lifespan without increasing the packet delay. We conduct experiments by simulations to evaluate the performance of the proposed protocol against existing ones, in terms of throughput and energy consumption. The experimental results demonstrated that the proposed protocol can deliver better energy distribution, extends the network lifetime up to 25% compared to simple opportunistic routing protocols and decreases the total energy consumption by 35% compared to traditional routing.

Prototypes of opportunistic Wireless Sensor Networks supporting indoor air quality monitoring

In this demonstration proposal we describe a prototype of a Wireless Sensor Network (WSN) for monitoring the air quality of an arbitrary indoor infrastructure environment. Specifically, the proposed demonstration deals with an application of wireless mesh networks for monitoring the carbon dioxide (CO2) levels of an indoor environment, supporting guaranteed real-time data acquisition and display. In the proposed demonstration we will illustrate a number of advantages of opportunistic routing, including dynamic node deployment and dynamic routing path selection, opportunistic resource utilization, robustness to interference and guaranteed multi-hop QoS (Quality of Service) for an indoor gas concentration monitoring network.

Angle-Based Dynamic Routing Scheme for Source Location Privacy in Wireless Sensor Networks

Subject monitoring and tracking is one of the most appealing classes of applications for Wireless Sensor Networks (WSNs). Numerous inch scale nodes can sense, collect and distribute crucial information with low deployment cost. For instance, the movement of endangered species in a national park can be monitored with a WSN. However, in such applications privacy issues can jeopardize the successful deployment of the network. An adversary might trace the network traffic over the same paths and eventually locate the source in the network. In this paper, we propose a source-location privacy scheme that employs randomly selected intermediate nodes based on inclination angles. The introduced Angle-based Dynamic Routing Scheme (ADRS) is analysed and is compared with the Phantom Single-path Routing Scheme (PSRS). Simulation results demonstrate that ADRS improves the safety period and the packet latency.

Feasibility study of photoplethysmographic signals for biometric identification

The utilization of photoplethysmographic (PPG) signals for biometric identification represents a novel approach in the area of secure authentication. PPG signals can be easily obtained with low cost and have great potential to serve as biometric identification mechanism. This paper explores the feasibility, along with the relevant signal processing methods, of using PPG signals of an individual as a biometric trait. PPG signals from two biometric datasets are examined. PPG signals were obtained from the fingertips of 29 healthy subjects. The experimental results demonstrate that PPG signals can be used as bio-measures for identification purposes given that PPG signals are collected under controlled environment and with accurate sensors.

Real-Time Indoor Carbon Dioxide Monitoring Through Cognitive Wireless Sensor Networks

In recent years, indoor air quality has become an important health and safety concern, as more energy efficient and air tight buildings are built and the existing buildings age. Clean air is essential for good health, and this is especially true when it comes to indoor air. However, many work environments lack proper detection mechanisms to identify health risks for occupants. Wireless ad hoc sensor networks have the potential to alleviate this problem. This paper presents a real-time cognitive wireless sensor network system for carbon dioxide monitoring at a complex indoor environment. The system aims to monitor and detect the concentration of carbon dioxide in a real-time basis and provide overall air quality alerts in a timely manner. Moreover, the system coexists with minimum interference with other systems in the monitoring area. A prototype is designed to show the enhanced real-time data transmission. Experiments are conducted to validate and support the development of the system for real-time monitoring and alerting.

Performance Comparison of Opportunistic Routing Schemes in Wireless Sensor Networks

Opportunistic routing is considered a promising direction for improving the performance of wireless sensor networks (WSN). In opportunistic routing, the intermediate nodes collaborate on packet forwarding in order to achieve high throughput in the face of lossy links. That makes the next node selection process crucial. In this paper, we are presenting an opportunistic routing protocol for wireless sensor networks. We also examine three extensions of that protocol, based on different next node selection criterion. We illustrate how each extension works and we evaluate and compare their performance in terms of energy consumption, delivery ratio and packet latency.

QoS and energy-aware dynamic routing in Wireless Multimedia Sensor Networks

The increasing availability of low-cost hardware along with the rapid growth of wireless devices has enabled the development of Wireless Multimedia Sensor Networks (WMSNs). Multimedia content such as video and audio streaming is transmitted over a WMSN which can easily be deployed with low cost. However, enabling real-time data applications in those networks demands not only Quality of Service (QoS) awareness, but also efficient energy management. Sensor network devices have limited energy resources. The limited energy poses significant threats on the QoS of WMSNs. In this paper, to improve the efficiency of QoS-aware routing, we examine an angle-based QoS and energy-aware dynamic routing scheme designed for WMSNs. The proposed approach uses the inclination angle and the transmission distance between nodes to optimize the selection of the forwarding candidate set and extend network lifetime. Simulation results indicate that considerable lifetime values can be achieved.

Acceptability and Quality of Experience in over the top video

Consumer acceptance is of great interest in the adoption of novel multimedia products and services. A number of factors can greatly influence the customer experience during a video session, impacting the acceptability of the product or service. Factors such as the Technical Quality (TQ) which covers the technical aspects of the signal quality can be controlled from the network provider. On the other hand, the network provider has no control on the subjects level of interest in a video, the Content Quality (CQ). Together TQ and CQ influence the Overall eXperience (OX) of the subject and, in the case of Over The Top (OTT) video, in a video session. In this paper, we present results from a user subjective study in which the impact of TQ and OX on the acceptability was investigated for OTT video sessions. To minimize the CQ impact on OX, the videos were carefully selected to have relatively neutral content. We assess the impact of TQ and OX on acceptability for videos containing impairment and failure events during lifecycle, thus affecting Accessibility, Retainability and Integrity. Our experimental results indicate that TQ and OX have a strong impact on acceptability.

Cognitive networking with opportunistic routing in Wireless Sensor Networks

Under the cognitive networking architecture, this paper presents an opportunistic routing protocol for cognitive radio in Wireless Sensor Networks (WSNs), which can deliver higher performance and efficiency in multihop wireless communications. Cognitive Networking with Opportunistic Routing, (CNOR), opportunistically routes traffic across paths over all available spectrum. A discrete event simulator is applied to evaluate and compare the proposed scheme against three other routing protocols: traditional routing with single channel, traditional routing with multiple channels and opportunistic routing with single channel. It is shown that by integrating opportunistic routing with cognitive radio much better results can be obtained, with respect to energy consumption, throughput and latency.