Moussa Ayyash

Internet of Things: A Survey on Enabling Technologies, Protocols, and Applications

This paper provides an overview of the Internet of Things (IoT) with emphasis on enabling technologies, protocols, and application issues. The IoT is enabled by the latest developments in RFID, smart sensors, communication technologies, and Internet protocols. The basic premise is to have smart sensors collaborate directly without human involvement to deliver a new class of applications. The current revolution in Internet, mobile, and machine-to-machine (M2M) technologies can be seen as the first phase of the IoT. In the coming years, the IoT is expected to bridge diverse technologies to enable new applications by connecting physical objects together in support of intelligent decision making. This paper starts by providing a horizontal overview of the IoT. Then, we give an overview of some technical details that pertain to the IoT enabling technologies, protocols, and applications. Compared to other survey papers in the field, our objective is to provide a more thorough summary of the most relevant protocols and application issues to enable researchers and application developers to get up to speed quickly on how the different protocols fit together to deliver desired functionalities without having to go through RFCs and the standards specifications. We also provide an overview of some of the key IoT challenges presented in the recent literature and provide a summary of related research work. Moreover, we explore the relation between the IoT and other emerging technologies including big data analytics and cloud and fog computing. We also present the need for better horizontal integration among IoT services. Finally, we present detailed service use-cases to illustrate how the different protocols presented in the paper fit together to deliver desired IoT services.

Coexistence of WiFi and LiFi toward 5G: concepts, opportunities, and challenges

Smart phones, tablets, and the rise of the Internet of Things are driving an insatiable demand for wireless capacity. This demand requires networking and Internet infrastructures to evolve to meet the needs of current and future multimedia applications. Wireless HetNets will play an important role toward the goal of using a diverse spectrum to provide high quality-of-service, especially in indoor environments where most data are consumed. An additional tier in the wireless HetNets concept is envisioned using indoor gigabit small-cells to offer additional wireless capacity where it is needed the most. The use of light as a new mobile access medium is considered promising. In this article, we describe the general characteristics of WiFi and VLC (or LiFi) and demonstrate a practical framework for both technologies to coexist. We explore the existing research activity in this area and articulate current and future research challenges based on our experience in building a proof-of-concept prototype VLC HetNet.

An Indoor Hybrid WiFi-VLC Internet Access System

Visible light communications (VLC) is emerging as a new alternative to the use of the existing and increasingly crowded radio frequency (RF) spectrum. VLC is unlicensed, has wide bandwidth, supports new levels of security due to the opacity of walls, and can be combined to provide both lighting and data communications for little net increase in energy cost. As part of a lighting system, VLC is ideal as a downlink technology in which data are delivered from overhead luminaries to receivers in the lighting field. However, realizing a symmetric optical channel is problematic because most receivers, such as mobile devices, are ill-suited for an optical uplink due to glare, device orientation, energy constraints. In this paper we propose and implement a hybrid solution in which the uplink challenge is resolved by the use of an asymmetric RF-VLC combination. VLC is used as a downlink, RF is used as an uplink, and the hybrid solution realizes full duplex communication without performance glare or throughput degradation expected in an all-VLC-based approach. Our proposed approach utilizes a software defined VLC platform (SDVLC) to implement the unidirectional optical wireless channel and a WiFi link as the back-channel. Experiments with the implemented prototype reveal that the integrated system outperforms conventional WiFi for crowded (congested) multiuser environments in term of throughput, and demonstrate functional access to full-duplex interactive applications such as web browsing with HTTP.

Design and analysis of a visible-light-communication enhanced WiFi system

Visible light communication (VLC) has wide unlicensed bandwidth, enables communication in radiofrequency-sensitive environments, realizes energy-efficient data transmission, and has the potential to boost the capacity of wireless access networks through spatial reuse. On the other hand, WiFi provides more coverage than VLC and does not suffer from the likelihood of blockage due to the line-of-sight requirement of VLC. In order to take the advantages of both WiFi and VLC, we propose and implement two heterogeneous systems with Internet access. One is the hybrid WiFi-VLC system, utilizing a unidirectional VLC channel as the downlink and reserving the WiFi backchannel as the uplink. The asymmetric solution resolves the optical uplink challenges and benefits from the full-duplex communication based on VLC. To further enhance the robustness and increase throughput, the other system is presented, in which we aggregate WiFi and VLC in parallel by leveraging the bonding technique in the Linux operating system. We also theoretically prove the superiority of the aggregated system in terms of average system delay. Online experiment results reveal that the hybrid system outperforms the conventional WiFi for crowded environments in terms of throughput and Web page loading time, and also demonstrate the further improved performance of the aggregated system when considering the blocking duration and the distance between the access point and the user device.

A Provably Efficient Online Collaborative Caching Algorithm for Multicell-Coordinated Systems

Caching at the base stations brings the contents closer to the users, reduces the traffic through the backhaul links, and reduces the delay experienced by the cellular users. The cellular network operator may charge the content providers for caching their contents. Moreover, content providers may lose their users if the users are not getting their desired quality of service, such as maximum tolerable delay in Video on Demand services. In this paper, we study the collaborative caching problem for a multicell-coordinated system from the point of view of minimizing the total cost paid by the content providers. We formulate the problem as an Integer Linear Program and prove its NP-completeness. We also provide an online caching algorithm that does not require any knowledge about the contents popularities. We prove that the online algorithm achieves a competitive ratio of O(log (n)), and we show that the best competitive ratio that any online algorithm can achieve is Ω (log (n) / log log (n)). Therefore, our proposed caching algorithm is provably efficient. Through simulations, we show that our online algorithm performs very close to the optimal offline collaborative scheme, and can outperform it when contents popularities are not properly estimated.

A Novel Quality of Service Assessment of Multimedia Traffic over Wireless Ad Hoc Networks

With the extensive growth of the Internet, wireless technology, and multimedia applications, quality of service (QoS) monitoring and measurement of the networks have become important. Network measurements are carried out to obtain information about important QoS parameters such as delay, loss and jitter. Each type of multimedia applications has its own requirements and limits on these parameters. To evaluate the QoS of multimedia applications transmitted over wireless networks, a fuzzy logic assessment system has been developed. The system showed how the end-to-end QoS could be measured without the necessity for complex mathematical models. The measured QoS were classified into three categories Good, Average, and Poor regions. In addition, and based on the proposed system, the distributions and the overall QoS were estimated. The results indicated that the measured QoS was a good indication of the network conditions and resource availability.

Spectrum Assignment in Cognitive Radio Networks for Internet-of-Things Delay-Sensitive Applications Under Jamming Attacks

The expected widespread usage of Internet-of-Things (IoT) devices and the associated diversity of applications will place extra pressure on network resources including bandwidth availability. In networking within IoT, spectrum scarcity requires the consideration of the adaptive cognitive radio (CR) technology to achieve interference-free and on-demand IoT solutions for a number of applications. However, CR networks share the same security weaknesses of legacy wireless networks. Jamming is considered a common attack, where jammers can attack networks in a proactive or reactive approach. In this paper, we study the channel assignment problem under both proactive and reactive jamming attacks. Specifically, we propose a novel probabilistic-based channel assignment mechanism that aims at minimizing the invalidity ratio of CR packet transmissions subject to delay constraints. The proposed scheme exploits the statistical information of licensed primary users activities, fading conditions and jamming attacks over idle channels to provide communicating CR IoT devices with the most secured channels of lowest invalidity ratios. Simulation results show that our proposed security, availability, and quality-aware channel assignment algorithm can significantly improve network performance.

Introduction to Mobile Ad-Hoc and Vehicular Networks

Mobile ad–hoc and vehicular networks are excellent examples of the proliferation of wireless data communication technologies. A mobile ad-hoc networks (MANET) consists of wireless devices which can dynamically be setup and can operate without any centralized control. One promising application of MANETs is the vehicular ad-hoc networks (VANETs). A VANET is a combination of an architectural network and an ad-hoc network. VANETs are distributed self-organizing networks of mobile vehicles. This chapter introduces both MANETs and VANETs, their characteristics and challenges, and presents the various protocols and applications optimized for them.

Visible Light Communication Module: An Open Source Extension to the ns3 Network Simulator With Real System Validation

The emergence of new physical media such as optical wireless and the ability to aggregate these new media with legacy networks motivate the study of heterogeneous network performance, especially with respect to the design of protocols to best exploit the characteristics of each medium. We consider visible light communications (VLC), which is expected to co-exist with legacy and future radio frequency (RF) media. While most of the research on VLC has been done on optimizing the physical medium, research on higher network layers is only beginning to gain attention, requiring new analyses and tools for performance analysis. To meet this need, we have developed a new ns3-based VLC module that can be used to study VLC-RF heterogeneous networks via simulation. The proposed ns3 module has been developed based on existing models for intensity modulated LED signals operating as lighting units transmitting to optical receivers at indoor scales (meters). These models and the corresponding simulation model are validated using a test bed implemented with a software-defined radio system, photo detector, phosphor-converted “white” LEDs, and under PSK and QAM modulation. Two scenarios are used in the validation of the VLC module: 1) using a receiver placed normal to the transmitter with varying range; and 2) using a receiver with a fixed range with varying angle of acceptance. Results indicate good correspondence between the simulated and actual test bed performance. Subsequently, we demonstrate how the VLC module can be used to predict the performance of a hybrid Wi-Fi/VLC network simulated using the ns3 environment with UDP, TCP, and combined network traffic.

Extending ns3 to simulate visible light communication at network-level

Visible light communications (VLC) describes the use of the visible spectrum for optical communications and has the potential to provide vast new wireless spectrum free from license. Most existing work on VLC focuses on the optimization of the physical medium rather than the networking context in which VLC will be deployed. Future deployments of VLC are expected to coexist with current RF technologies; complicating performance analysis of these integrated, heterogeneous systems. In this paper, we propose an extension of the ns3 network simulator as a means to investigate the performance of these heterogeneous RF/VLC networks. The proposed VLC module realizes physical layer models characterizing the visible spectrum mapped to various optical modulation schemes. We also consider device mobility and orientation which uniquely impact an optical receiver. We describe the adopted physical models, the structure of the ns3 model implementation, and demonstrate performance assessment for an asymmetric RF/VLC scenario. In this case, the VLC downlink and the RF (WiFi) uplink are paired using the combination of our new ns3 VLC component and existing ns3 RF modules. Simulations demonstrate how this scenario can be studied in terms of VLC signal to noise ratio (SNR) and bit error rate (BER) parameters, and in the resulting network performance measured as goodput.