Abdelhakim Senhaji Hafid

Abdelhakim Senhaji Hafid
Université de Montréal | UdeM · Department of Computer Science and Operations Research

About

306
Publications
53,386
Reads
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4,218
Citations
Citations since 2016
103 Research Items
2594 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
Introduction
Abdelhakim Senhaji Hafid was a Senior Research Scientist with Bell Communications Research (Bellcore), NJ, USA, where he spent several years working in the context of major research projects on the management of next generation networks. He is currently a Full Professor with the University of Montreal. He is also the Founding Director of the Network Research Laboratory (http://www.iro.umontreal.ca/~labolrc/pubs.html) and the Montreal Blockchain Laboratory.

Publications

Publications (306)
Conference Paper
In the context of blockchain protocols, each node stores the entire state of the network and processes all transactions. This ensures high security, but limits scalability. Sharding is one of the most promising solutions to scale blockchain. In this paper, we analyse the security of three Sharding-based protocols using tail inequalities. The key co...
Article
Full-text available
The Fog computing paradigm has appeared as a geo-distributed response to a growing focus on latency-sensitive Internet of Things (IoT) applications and the long-delay that may be provided by Cloud Data Centres. Although many researchers have investigated how IoT can interact with a Fog, very few have tackled the question of how to construct a Fog i...
Article
Full-text available
A steady increase in Internet of Things (IoT) applications needing large-scale computation and long-term storage has lead to an over-reliance on Cloud computing. The resulting network congestion in Cloud, coupled with the distance of Cloud data centres from IoT, contribute to unreliable end-toend response delay. Fog computing has been introduced as...
Article
Full-text available
The advent of miniaturized mobile devices with wireless communication capability and integrated with biosensors has revolutionized healthcare systems. The devices can be used by individuals as wearable accessories to collect health data regularly. This type of medical assistance supported by mobile devices to monitor patients and offer health servi...
Article
Full-text available
Cryptocurrencies (e.g., Bitcoin and Ethereum), which promise to become the future of money transactions, are mainly implemented with blockchain technology. However, blockchain suffers from scalability issues. Sharding is the leading solution for blockchain scalability. Sharding splits the blockchain network into sub-chains called shards/committees....
Preprint
The advent of Cloud Computing enabled the proliferation of IoT applications for smart environments. However, the distance of these resources makes them unsuitable for delay-sensitive applications. Hence, Fog Computing has emerged to provide such capabilities in proximity to end devices through distributed resources. These limited resources can coll...
Article
Data-driven Machine and Deep Learning (ML/DL) is an emerging approach that uses medical data to build robust and accurate ML/DL models that can improve clinical decisions in some critical tasks (e.g., cancer diagnosis). However, ML/DLbased healthcare models still suffer from poor adoption due to the lack of realistic and recent medical data. The pr...
Article
IoT connects a large number of physical objects with the Internet that capture and exchange real-time information for service provisioning. Traditional network management schemes face challenges to manage vast amounts of network traffic generated by IoT services. Software-Defined Networking (SDN) and Information-Centric Networking (ICN) are two com...
Article
Full-text available
Blockchain systems have seen much growth in recent years due to the immense potential attributed to the technology behind these systems. However, this popularity has outlined a critical scalability issue that most blockchain systems are now confronted with. With their increasing popularity comes an increasing amount of load on the system. Several s...
Article
In the era of Industry 4.0, Internet of Things (IoT) technologies play an important and enabling role. IoT technologies support the capture (and increasingly processing) of data close to the point of data capture, and can be used as a basis to establish a sustainable model for cities and to preserve the quality of life of citizens. However, the imp...
Article
Blockchain like Bitcoin and Ethereum suffer from scalability issues. Sharding is one of the most promising and leading solutions to scale blockchain. The basic idea behind sharding is to divide the blockchain network into multiple committees, where each processing a separate set of transactions, rather than the entire network processes all transact...
Article
Full-text available
Recent advances in Intelligent Transport Systems (ITS) and Artificial Intelligence (AI) have stimulated and paved the way toward the widespread introduction of Autonomous Vehicles (AVs). This has opened new opportunities for smart roads, intelligent traffic safety, and traveler comfort. Autonomous Vehicles have become a highly popular research topi...
Preprint
Full-text available
Blockchain was always associated with Bitcoin, cryptocurrencies, and digital asset trading. However, its benefits are far beyond that. It supports technologies like the Internet-of-Things (IoT) to pave the way for futuristic smart environments, like smart homes, smart transportation, smart energy trading, smart industries, smart supply chains, and...
Article
Full-text available
Internet of Things (IoT) applications depend on reliable external storage and processing such as Cloud data centres. In response to high latency from Cloud, fog-computing has been introduced as a network of micro-data centres closer to IoT devices that provides a geo-distributed low-latency response. Current contributions regarding design & dimensi...
Article
Mobile edge computing (MEC) is an emerging paradigm that provides radio access net- works with augmented resources to meet the requirements of Internet of Things (IoT) services. MEC allows IoT devices to offload delay sensitive and computation intensive tasks to edge clouds deployed at base stations (BSs). Offloading tasks to edge clouds can allev...
Chapter
In recent years, there has been a huge increase in the number of attacks that cause huge damage and financial losses for both educational and business organizations. Intrusion detection systems (IDSs) play a key role in ensuring network security. With the emergence of new types of security threats, traditional IDSs based on pattern matching and sig...
Book
Full-text available
Presents blockchain techniques and applications for cyber-physical systems Analyzes and presents the state-of-the-art of blockchain technology Highlights and discusses the recent development and emerging trends in blockchain for CPS applications
Conference Paper
Recently, software defined networks (SDN) has emerged as novel technology that leverages network programmability to facilitate network management. SDN provides a global view of the network, through a logically centralized component, called SDN controller, to strengthen network security. SDN separates the control plane from the data plane, which all...
Preprint
Full-text available
Blockchain technology has been gaining great interest from a variety of sectors, including healthcare, supply chain and cryptocurrencies. However, Blockchain suffers from its limited ability to scale (i.e. low throughput and high latency). Several solutions have been appeared to tackle this issue. In particular, sharding proved that it is one of th...
Article
Mobile crowdsensing (MCS) is a promising paradigm of large-scale sensing. A group of mobile users are recruited with their smart devices to accomplish various sensing tasks in specific areas. The mobility and intelligence of mobile users enable MCS to achieve a sufficient coverage ratio of sensing tasks or areas. Currently, MCS is generally propose...
Article
Full-text available
In the face of cooperative intelligent transportation systems (C-ITS) advancements, the inclusion of vulnerable road users (VRU), i.e., pedestrians, cyclists, and motorcyclists, has just recently become a part of the discussion. Including VRU in C-ITS presents new challenges, most notably the trade-off between the increase in VRU safety and the agg...
Preprint
Full-text available
Blockchain like Bitcoin and Ethereum suffer from scalability issues. Sharding is one of the most promising and leading solutions to scale blockchain. The basic idea behind sharding is to divide the blockchain network into multiple committees, where each processing a separate set of transactions, rather than the entire network processes all transact...
Conference Paper
Mobile crowdsensing (MCS) is a method of data collection by recruiting mobile devices to accomplish sensing tasks. The mobility of smart devices provides an energy-efficient solution to applications of large-scale sensing, e.g., smart city. Unmanned aerial vehicles (UAVs) enables new business opportunities (e.g., package delivery) with its rapid in...
Conference Paper
The emergence of Internet of Energy (IoE) paves the way for sustainable and green energy environments that reduce energy costs and integrate Renewable Energy Sources (RESs) as new sources of energy. Electric vehicles (EVs) are one of the main actors of IoE future. The emergence of EVs promises to reduce the environmental crisis (e.g., carbon emissi...
Article
Full-text available
With the proliferation of embedded technologies and wireless capabilities, today’s vehicles are no longer isolated mechanical machines. They become part of a hyper-connected system -Intelligent Transportation Systems (ITS)- that has the potential to support multiple levels of autonomy and intelligence improving considerably the safety, efficiency,...
Article
In this work, we introduce a methodology that takes advantage of the inherent network diversity present in vehicular communications to improve the performance of safety applications. This methodology is based on a framework that simultaneously exploits the strengths of each individual network by using a set of decision rules. The implementation beg...
Article
Mobile crowdsensing (MCS) is a new and promising paradigm of data collection due to the growing number of mobile smart devices. It can be utilized in applications of large-scale sensing by employing a group of mobile users with their smart devices. Since a large number of mobile users are recruited, the allocation of sensing tasks to mobile users h...
Article
Reliability is a key requirement of multi-hop safety message broadcasting. DSRC/802.11p MAC layer has strict reliability requirement for ITS safety applications. In city environment, transmission in wireless medium is vulnerable to packet collisions and interferences. Cross channel interference is quite predominant in the presence of high rise buil...
Article
As one of the most devastating types of Distributed Denial of Service (DDoS) attacks, Domain Name System (DNS) amplification attack represents a big threat and one of the main Internet security problems to nowadays networks. Many protocols that form the Internet infrastructure expose a set of vulnerabilities that can be exploited by attackers to ca...
Article
Full-text available
Blockchain (e.g., Bitcoin and Ethereum) has drawn much attention and has been widelydeployed in recent years. However, blockchain scalability is emerging as a challenging issue. This paper outlines the existing solutions to blockchain scalability, which can be classified into two categories: first layer and second layer solutions. First layer solut...
Article
Full-text available
Convergence of physical and digital identity and integration of various individual records, such as patient data, into a united repository remains a serious challenge. On one hand, collecting relevant data can help clinicians, specialists and healthcare service providers to facilitate care for patients. On the other hand, Self-Sovereign identity an...
Chapter
Full-text available
The convergence of Internet of Things (IoT), Artificial Intelligence (AI), 5G, Big Data and cloud computing technologies is creating an emerging edge to cloud computing model to overcome the challenges of traditional cloud computing in supporting the upcoming Internet of (smart and autonomous) things. Edge computing complements cloud computing by o...
Conference Paper
Nowadays, blockchain technology is seen as one of the main technological innovations to emerge since the advent of the internet. Many applications can benefit from blockchain to protect their exchanges. Nonetheless, applications with more restricted interests cannot use public blockchains. Permissioned blockchains promise to combine effectiveness o...
Conference Paper
Smart grids (SGs) and advanced metering infrastructures (AMIs) are considered as the new evolution of classical electrical grids. The recent emergence of smart meters is paving the way for the proliferation of smart grids, where billions of smart meters are interconnected to provide novel pervasive services (e.g., real time pricing application and...
Article
Vehicular safety applications based on DSRC/802.11p have strict reliability requirement (greater than 0.99). However, it is difficult to achieve high reliability in wireless medium as the transmission is vulnerable to various wave propagation issues. To the best of our knowledge, none of the existing emergency message dissemination schemes, in the...
Chapter
An Ethereum transaction is defined as the method by which the external world interacts with Ethereum. More and more users are getting involved in cryptocurrencies like Ethereum and Bitcoin. With a sudden increase in the number of transactions happening every second and the capital involved in those transactions, there is a need for the users to abl...
Chapter
In the context of blockchain protocols, each node stores the entire state of the network and processes all transactions. This ensures high security but limits scalability. Sharding is one of the most promising solutions to scale blockchain. In this paper, we analyze the security of three Sharding-based protocols using tail inequalities. The key con...
Article
Full-text available
In the context of blockchain protocols, each node stores the entire state of the network and processes all transactions. This ensures high security but limits scalability. Sharding is one of the most promising solutions to scale blockchain. The basic idea of sharding is to split/divide the entire network into multiple committees/ shards, each of wh...
Technical Report
Full-text available
Blockchain offers a decentralized, immutable, transparent system of records. It offers a peer-to-peer network of nodes with no centralised governing entity making it ‘unhackable’ and therefore, more secure than the traditional paper-based or centralised system of records like banks etc. While there are certain advantages to the paper-based recordin...
Preprint
Full-text available
Blockchain offers a decentralized, immutable, transparent system of records. It offers a peer-to-peer network of nodes with no centralised governing entity making it unhackable and therefore, more secure than the traditional paper-based or centralised system of records like banks etc. While there are certain advantages to the paper-based recording...
Conference Paper
Full-text available
The Low Power Wide Area (LPWA) networks are expected to enable the massive connectivity of small and constrained devices to the Internet of Things. Due to the restricted nature of both end devices and network links, LPWA technologies employ network stacks that often do not define an interoperable network layer; instead, application data is usually...
Conference Paper
Full-text available
Although Federated Learning allows for participants to contribute their local data without it being revealed, it faces issues in data security and in accurately paying participants for quality data contributions. In this paper, we propose an EOS Blockchain design and workflow to establish data security, a novel validation error based metric upon wh...
Article
Full-text available
With the exponential growth in the number of insecure devices, the impact of Distributed Denial-of-Service (DDoS) attacks is growing rapidly. Existing DDoS mitigation schemes are facing obstacles due to low flexibility, lack of resources and high cost. The new emerging technologies, such as blockchain, introduce new opportunities for low-cost, effi...
Article
The opportunistic utilization of access devices to offload mobile data from cellular network has been considered as a promising approach to cope with the explosive growth of cellular traffic. To foster this opportunistic utilization, we consider a mobile data offloading market where mobile network operator (MNO) can sell bandwidth made available by...
Article
Renewable energy sources (RESs) and energy storage systems (ESSs) are the key technologies for smart grid applications and provide great opportunities to de-carbonize urban areas, regulate frequency, voltage deviations, and respond to severe time when the load exceeds the generation. Nevertheless, uncertainty and inherent intermittence of renewable...
Article
Full-text available
With the emergence of Internet of Things (IoT), where any device is able to connect to the Internet and monitor/control physical elements, several applications were made possible such as smart cities, smart health care and smart transportation. The wide range of the requirements of these applications drives traditional IoT to cognitive IoT (CIoT) t...
Conference Paper
An Ethereum transaction is defined as the method by which the external world interacts with Ethereum. More and more users are getting involved in cryptocurrencies like Ethereum and Bitcoin. With a sudden increase in the number of transactions happening every second and the capital involved in those transactions, there is a need for the users to abl...
Article
Full-text available
In channel-hopping (CH) based distributed cognitive radio networks (CRNs), the time duration that secondary users (SUs) spend for establishing communication links is called access delay. To evaluate access delay, we propose an access delay model by jointly considering imperfect spectrum sensing and multi-channel multi-SU transmission, from the cros...
Conference Paper
Nowadays, blockchain is seen as one of the main technological innovations. Many applications can rely on the blockchain to secure their exchanges. However, applications with private interest cannot rely on public blockchains. First, in a public blockchain, anyone can read the whole data of the blockchain. Second, anyone can participate to the "cons...
Conference Paper
Full-text available
In this paper, we propose an optimization approach on access delay by jointly modeling imperfect spectrum sensing and multi-channel multi-secondary user (SU) access contention, from a cross-layer perspective, for channel-hopping (CH) based cognitive radio networks (CRNs). Specifically, we first employ an absorbing Markov chain to model the multi-SU...
Article
The Wireless Access for Vehicular Environment (WAVE) mandates that data packets of non-safety applications are to be sent within WAVE basic service sets (WBSS). These WBSS are to be established on the least congested service channels. WAVE proposes a mechanism to select such channels; yet, owing to vehicles’ high mobility, there is high chance of h...
Article
Heterogeneous Vehicular Networks (HetVNets) provide great potential for on-demand services. Such services require real-time request-reply routing between vehicles as clients and service providers as the source. One naïve solution to deliver service is unicasting between service provider and each client. Unicasting consumes considerable bandwidth, s...
Article
Cellular network is facing severe traffic overload problem caused by phenomenal growth of mobile data. Offloading part of the mobile data traffic from cellular network to alternative networks is a promising solution. In this paper, we study mobile data offloading problem under the architecture of mobile cloud computing (MCC), where mobile data can...
Conference Paper
Software Defined Networking (SDN) has been already used in recent literature to add flexibility and programmability to Vehicular Ad hoc Networks (VANETs). However, there are numerous open issues in implementing SDN for central control and management of VANETs. One open problem is how to adapt SDN for routing data from a source to a destination in V...
Article
The tradeoff between decreasing the interference to primary user (PU) and increasing secondary users’ (SUs’) achievable throughput is an important problem in cognitive radio networks. Heterogeneous fading channels from PU to multiple SUs, PU’s traffic distribution, limited SU’s power and multiple SUs’ access contention impact both these two conflic...
Article
Full-text available
Mobile cloud computing is a revolutionary computing paradigm for mobile applications, which enables storage and computation migration from mobile users to resource-rich and powerful cloud servers. This migration causes some privacy issues in providing secure data storage, fine-grained access control and anonymity of users. Attribute-based encryptio...
Conference Paper
Vehicular ad hoc networks (VANET) are a specific type of networks, wherein nodes are vehicles equipped with wireless receivers. The vehicles can exchange data by using wireless communication either in ad-hoc mode or infrastructure mode through equipments installed on the road side. In vehicular networks, clustering is one of the main dissemination...
Conference Paper
Full-text available
—Recently, Jung et al. [1] proposed a data access privilege scheme and claimed that their scheme addresses data and identity privacy as well as multi-authority, and provides data access privilege for attribute-based encryption. In this paper, we show that this scheme, and also its former and latest versions (i.e. [2] and [3] respectively) suffer fr...
Article
Vehicles have embedded software dedicated to diverse functionally ranging from driving assistance to entertainment. Vehicle manufacturers often need to perform updates on software installed on vehicles. Software updates can either be pushed by the manufacturer to install fixes, or they can be requested by vehicle owners to upgrade some functionalit...
Conference Paper
Full-text available
Mobile cloud computing is envisioned as a promising framework to augment data transmission capabilities of mobile devices. In this paper, we propose two game theoretic mechanisms for achieving efficient data offloading for mobile cloud computing. We formulate the decentralized data offloading decision making problem among mobile device users as dat...
Article
Full-text available
Network stability is a key performance metric in supporting real time communication over wireless networks. Because of high bandwidth demand and dynamic traffic variation, several paths in Wireless Mesh Networks (WMNs) are expected to be unstable. High levels of network instability can lead to interferences, packet losses and high delays. In this p...
Conference Paper
In this paper, we study mobile data offloading problem under the architecture of mobile cloud computing (MCC), where mobile data can be delivered by cellular, WiFi and terminal-to-terminal (T2T) networks. In order to minimize the overall cost for data delivery task, it is crucial to reduce cellular network usage while satisfying delay requirements....
Conference Paper
This paper proposes two Markovian models to analyze the performance of IEEE 802.11p EDCA mechanism for vehicle-to-vehicle (V2V) infotainment applications. The first model describes the backoff procedure and is used to compute the transmission probability of each access category (AC) while the second illustrates the contention phase after a busy cha...