Hussein Khaleel

Impact of Wi-Fi traffic on the IEEE 802.15.4 channels occupation in indoor environments

This paper investigates the IEEE 802.15.4 channel occupation pattern under Wi-Fi IEEE802.11b traffic, to provide a better understanding of the cross-interference and the coexistence between these two standards. The overcrowding of the ISM band centered around 2.4 GHz is becoming in fact a serious challenge for the development of the next-generation networks operating in these bands (e.g., ad-hoc, low-power networks). The analysis of this paper is based on experimental measurements carried out using an IEEE 802.15.4 Wireless Sensor Network (WSN) node with Wi-Fi interference at different traffic rates. Three propagation environments are considered: an anechoic chamber, a realistic indoor environment with negligible background interference, and the same environment with high background interference. The measured data are analyzed in terms of energy probability distributions and spectrograms, to characterize the occupation of the IEEE 802.15.4 channels from a statistical and temporal perspective. Finally, the outage probability is introduced as a metric to evaluate the potential impact of Wi-Fi interference on the considered channels.

Bringing the Internet of Things along the manufacturing line: A case study in controlling industrial robot and monitoring energy consumption remotely

The Internet of Things (IoT) concept attracts considerable interest from the academia and industry. This paper provides a set of proof-of-concept prototype descriptions, based on such IoT exploitation, which aim at gathering real-time data along the manufacturing processes that enables a responsive production management and maintenance, including energy consumption and water usage monitoring at each stage of a production cycle. The presented work takes advantage of the ebbits platform, which provides a middleware infrastructure for integrating industrial sensors, devices and emerging wireless technology in the physical world, transforming them into web services that enable seamless integration into mainstream business system such as MES and ERP.

Frequency Agile Wireless Sensor Networks: Design and Implementation

In this paper we propose an integration of dynamic channel allocation capabilities, typical of cognitive radio networks, in wireless sensor networks based on IPv6 protocol. We analyze the fundamental aspects of the proposed frequency-agile wireless sensor networks, including spectrum sensing, channel selection, network architecture, extensions of the IPv6 stack, and system operation. We then present a complete implementation of a prototype which illustrates feasibility and effectiveness of the proposed solutions. Results show that dynamic frequency allocation provides significant improvement of performance and reliability in wireless sensor networks operating in highly interfered environments.

Frequency agility in IPv6-Based wireless personal area networks (6LoWPAN)

This paper presents a demonstrator of a multi-hop 6LoWPAN provided with frequency-agility extensions. A reference architecture is presented along with the basic components introduced to build a distributed spectrum sensing and interference resolution service in a multi-hop environment. Moreover, a frequency-agility management plane is proposed for the 6LoWPAN communication stack. The proposed solution is implemented in a small-scale network adopting TinyOS and an open-source implementation of 6LoWPAN protocol stack. The resulting demonstrator proves the capability of the proposed system to characterize the spectrum occupancy state in a multi-hop environment. In addition, it shows the ability of the network to reallocate to the best available channel in case a critical level of interference is detected on the current operating channel.

Heterogeneous Applications, Tools, and Methodologies in the Car Manufacturing Industry Through an IoT Approach

Due to the growth of industrial Internet services, todays production environment is on the edge of a new era of innovations and changes. This is taking place through the convergence of the global industrial system with the power of advanced computing, analytics, low-cost sensing, and new levels of connectivity enabled by the Internet of Things (IoT). These innovations will bring higher efficiency, flexibility, and interoperability among industries, although they belong to different production ecosystems. This paper describes an IoT platform and the related prototypes developed within the project: Enabling Business-Based Internet of Things and Services (ebbits), with a focus on the industrial domain. Heterogeneous applications were deployed and tested, including a wireless sensor and actuator network for industrial machines monitoring and a radio-frequency-identification-based system for operator management, locating, and authorization, which also includes an interactive user interface for portable devices to visualize real-time information from physical-world devices. Moreover, tools for model-driven development are used to simplify the process of building IoT applications. Those developments are based on IoT middleware that is developed and deployed by the project to enable the seamless integration of heterogeneous technologies and processes into mainstream enterprise systems. This paper also presents the prototypal deployment of the developed prototypes in the car manufacturing industry.

Distributed spectrum sensing and channel selection in opportunistic wireless personal area networks

This demonstrator showcases a distributed spectrum sensing and channel selection service running on a small-scale IEEE 802.15.4 opportunistic WPAN network. This service can provide spectrum awareness to the network itself or to other co-located networks. In case an interfering signal is detected the network devices are able to identify less used spectrum portions such that the network can reallocate to the best available channel. The channel occupancy can be observed in real-time via a graphical user interface.

On spectrum sensing duration in cognitive wireless sensor networks

Frequency agility is considered as an indispensable feature of next-generation wireless sensor networks (WSNs), which will have to cope with highly interfered environments due to the increasing diffusion of wireless devices operating in unlicensed bands. In this paper we investigate some design aspects related to spectrum sensing in “cognitive” WSNs, relating the duration of sensing time to the probability of error in channel selection and analyzing the tradeoff between sensing duration and average throughput. Results are based on a realistic model, consistent with previous experimental works and existing testbeds.

Underlying connectivity mechanisms for multi-radio wireless sensor and actuator networks

This work proposes mechanisms enabling connectivity in multi-radio wireless sensor and actuator networks, namely: network discovery, interface/channel switching, and connection-loss recovery. The considered mechanisms are optimized with the aim to maximize the availability of system services (minimize network down-time) and achieve an increased overall robustness. The proposed approach offers dynamicity and adaptability to the constantly changing operating conditions of the different radio interfaces as well as to application-level requirements, and ensures self-organizing and autonomous operations.

Multi-access interface selection based on data mining algorithm

Multi-access networks are envisioned to guarantee a continuous service while addressing different application requirements in terms of data rate, coverage and power consumption. Different access technologies can be effectively combined in a multi-access scenario where the overall system is able to achieve a better performance leveraging on the different characteristics of the access technologies. One of the main challenges in realizing a multi-access system is the process of properly selecting a network interface. This paper proposes a network selection algorithm based on the k-nearest neighbor data mining classification technique. This work considers Ethernet, Wi-Fi, and 3GPP technologies; however, the proposed approach could be easily adapted to take into account other access technologies.

Prototyping the Internet of Things for the future factory using a SOA-based middleware and reliable WSNs

In this paper, we describe a SOA-based middleware to integrate Internet-of-Things technologies in industrial setups. The middleware allows a seamless horizontal integration among heterogeneous technologies and vertical integration with applications and business systems. Using the middleware, we evaluated an approach to improve the reliability of 6LoWPAN-based sensor networks with self-configuration and self-healing capabilities to support an innovative monitoring and control framework in a manufacturing line. The sensor networks were evaluated in a test bed consisting of various physical devices that emulates a welding station.