Bitcoin’s success as a global cryptocurrency has paved the way for the emergence of blockchain, a revolutionary category of distributed systems. However, the growing popularity of blockchain has led to a significant divergence from its core principles in many systems labeled as “blockchain.” This divergence has introduced complexity into the blockchain ecosystem, exacerbated by a lack of comprehensive reviews on blockchain and its variants. Consequently, gaining a clear and updated understanding of the diverse spectrum of current blockchain and blockchain-like systems has become challenging. This situation underscores the necessity for an extensive literature review and the development of thematic taxonomies. This survey seeks to offer a comprehensive and current assessment of existing blockchains and their variations while delineating the boundaries between blockchain and blockchain-like systems. To achieve this objective, we propose a holistic reference model for conceptualizing and analyzing these systems. Our layer-wise framework envisions all distributed ledger technologies (DLTs) as composed of four principal layers: data, consensus, execution, and application (DCEA). In addition, we introduce a new taxonomy that enhances the classification of blockchain and blockchain-like systems, offering a more useful perspective than existing works. Furthermore, we conduct a state-of-the-art review from a layered perspective, employing 23 evaluative criteria predefined by our framework. We perform a qualitative and quantitative comparative analysis of 44 DLT solutions and 26 consensus mechanisms while discussing differences and boundaries between blockchain and blockchain-like systems. We emphasize the significant challenges and tradeoffs encountered by distributed ledger designers, decision-makers, and project managers during the design or adoption of a DLT solution. Finally, we outline crucial research challenges and directions in the field of DLTs.

As Mobile Network Operators (MNOs) prepare to interconnect diverse technologies to existing cellular networks, it is critical to assess the capabilities of the network architecture to handle such changes. One key area to consider is the subscription management process, which governs the user's profile management, authentication, and access control. This process operates centrally, which affects users' security, accessibility, and privacy. Additionally, it increases the system's complexity when handling the large volume of messages sent over networks like IoT. In this work, we propose a Blockchain-based subscription management approach for next generation cellular networks to address the challenges in user profile management and the Authentication and Key Agreement (AKA) process. The method uses a hybrid cryptosystem technique to protect the user's privacy. Based on the evaluation, the system can handle the AKA process with fewer messages passing while improving system availability by utilizing distributed network functions and storage. Finally, we highlight some key points to consider when implementing our proposed approach.

Trust is an important factor in the success of P2P networks. It is needed to ensure that nodes in the network can be trusted to behave honestly and to deliver on their promises (e.g sharing resources). While traditional reputation trust management systems (RTMS) such as BTrust or EigenTrust have proven effective, there is room for further enhancement by integrating advanced graph neural network (GNN) models. This paper proposes a novel approach to enhance Trust Management Systems (TMS) by incorporating an Edge-Feature Attention Mechanism into the Edge Graph Neural Network (EGNN) model, which takes into account the direction of edges. The proposed GBTrust model is specifically designed for trust management in P2P networks, leveraging the interactions and relationships among peers. By incorporating the Edge-Feature Attention Mechanism, the model dynamically assigns importance to different edge features based on their relevance, thereby improving the discrimination of the importance of various neighbors and edge features in the network graph. The GBtrust model aims to provide more accurate and adaptive detection of malicious peers, thereby enhancing the overall security and reliability of P2P networks.

We present the deployment procedure of a private 4G-LTE network with standard User Equipment in two different scenarios using OpenAirInterface and Magma core networks. Our lessons learned from deploying the segregated end-to-end cellular network testbed, comparison of connection performance in two scenarios, challenges of connecting smartphones to the network, and comparison among the possible use-cases with each scenario are the highlighted subjects provided in this paper.

In recent years, Blockchain arose as a key technology in building autonomous decentralised financial systems. Its ability to digitize trust enables building trustless systems such as cryptocurrencies where users do not need to rely on any third party to exchange value. The success of cryptocurrencies to operate without any intermediaries draw the interest of business operators who seek to bypass intermediation and thus to reduce cost and gain competitive advantages. As a result, Blockchain was used outside the crypto-sphere to build decentralized systems. However, this portage led to the inception of new types of Blockchains adapted to different specifications and with different designs. Consequently, the technology has diverged from its baseline (Bitcoin) to the point where some systems marketed as “blockchain” share only a few design concepts with the original Blockchain design proposed by Satoshi Nakamoto. This conceptual divergence alongside the lack of comprehensive models and standards made it difficult for both system designers and decision-makers to clearly understand what is a blockchain or to choose a suitable solution.This survey has a double goal; on the one hand, it attempts to contribute to the discussion on the ontological status of DLTs by providing a taxonomy oriented-framework (DCEA) for conceptualizing and examining DLT. On the other hand, it also attempts to present an up-to-date review and evaluation of current blockchains and their variants as constructed of four layers: the data, consensus, execution and application layers.

In centralized infrastructures, users are not capable of authenticating themselves, in identity management systems, beyond their application’s domain. Users are forced to trust their service providers for identification and data management. Such solutions have experienced large-scale data breaches and are cumbersome for users to remember the credentials for multiple sites. Furthermore, users have very little control over their data. The concept of decentralized identity has raised the possibility of better managing these concerns. It allows users to share only the relevant part of their personal information with a service provider to verify their digital identity. We propose OrgID, a decentralized identity and user-centric data management platform including identity registration and authorization procedures. Our approach supports self-sovereign identity architecture leveraged by blockchain. This method consists of a one-time proof-verification mechanism that facilitates the secure access and credibility of digital information. Moreover, users can maintain their identities associated with specific attributes and rely on a proof mechanism using smart contracts. It deploys a platform where user registration and authorization no longer involve a central service provider. We implemented the proposed solution using smart contracts on a private Ethereum blockchain. We further analyzed the performance of these processes regarding the system’s scalability to evaluate how they manage latency and the number of users. The results state that the system is highly scalable to manage a large number of users and the system’s latency is adjustable based on the application needs.

The fifth generation of mobile cellular networks (5G) is designed to support a set of new requirements and use cases, including connectivity for the IoT (Internet of Things). Due to the industry and the user's expectation of having connectivity embedded into IoT devices, the “wholesale wireless connectivity” concept is gaining more and more attention. According to this concept, connectivity providers sell connectivity to 3rdparties, which in turn provide it to their own devices. However, this concept brings also new architecture and security requirements that are not fully addressed by the state of the art. Taking advantage of the flexibility provided by virtualization technologies (including network slicing), we propose in this paper a new 5G-SSAAC (5G Slice Specific Authentication and Access Control) mechanism that delegates authentication and access control of the devices to the 3rdparties providing these devices, thereby decreasing the load of the connectivity provider's CN (core network), while increasing flexibility and modularity of the whole 5G network.

This dissertation paper synthesizes our contributions in the network openness context to achieve a flexible and dynamic Network-as-a-Service (NaaS). Tackling several challenges, the research work we have conducted have led us to three main proposals. First, we elaborate a software design approach complemented with a functional decomposition approach for modeling Virtual Network Functions (VNFs) as (micro)services (as-a-Service model). Then, we define a global NaaS architectural framework for hosting, exposing and deploying VNFs and virtual networks as network slices. Finally, we develop models for on- demand deployment, dynamic orchestration, and automatic life- cycle management of VNFs and virtual network slices in NaaS.

Changes in the technological and societal environments that surround organisations have disrupted the classic governance frameworks that corporate and information technology (IT) managers have designed to align IT uses with organisational missions, strategy, and values. The formerly “sovereign territory” of IT departments has been invaded, jeopardised by the autonomy of individual users and the changing nature of IT. Thus questions of IT governance in the age of IT consumerisation are highly critical. In response, this theoretical article introduces an alternative approach, relying on the philosophy of Michel Foucault and his concept of governmentality. The proposed liberal model of IT governance provides a sound foundation to address the challenges associated with modern technological and societal environments in which today’s organisations must evolve. The inferences and analytic implications related to this new liberal model of IT governance lead to the development of a set of governance principles and propositions to guide practice and further research.

In the context of Network-as-a-Service (NaaS) for network operators openness towards Over-The-Top (OTTs) players, we propose an “On-demand and Dynamic Deployment Model for Virtual Network Functions (VNFs)”. We consider both, Telco's needs for more dynamicity in network service delivery, and OTTs' needs for network functions that support requirements of applications at the network-level. In order to allow third-party applications to request deployment of VNFs for specific needs, the proposed deployment model is based on an exposition approach that uses Network APIs over Network Functions Virtualization (NFV) Management and Orchestration modules. To illustrate the proposed model, we focus on Web Real-Time Communications (WebRTC). WebRTC applications are versatile and have strong needs for network functions which makes them a relevant use-case. We have implemented the proposed approach on OPNFV platform. We exploit the “at-the-edge” feature and location-awareness to respect the time-sensitivity and QoS constraints of WebRTC communications. For faster VNF instantiation, we rely on container-based virtualization (Docker containers). Finally, we perform experiments and evaluate the advantages of this model comparing to legacy and alternative approaches.

The sharp rise of OTT application services in recent years has called for greater application-to-network visibility. These dynamic application services represent a foremost drive in the communication ecosystem changes. However, the tight coupling between network services and network infrastructures pose challenges for network providers. They need more dynamicity in their network architectures to meet the requirements of application services. SDN and NFV is the combination of networking technologies that facilitate such an evolution. But is it sufficient to allow dynamic application-to-network interactions? In this paper, we rely on SDN-enabled NFV assets as a strong foundation to propose a dynamic and adaptable “Network-as-a-Service” architecture. We leverage our NaaS proposal with a resilient Network Exposition Layer allowing to express offers and demands of network services. To demonstrate the offered features, we propose three architecture deployment models: broad, customized and event-based dynamic model. We then instantiate our architecture within the WebRTC-based communication services, illustrating the collaboration between network providers and Communication Service Providers (CSPs).

We present in this paper the implementation of the networking part of a Network-as-a-Service (NaaS) architecture based on SDN-enabled NFV using as a basis the OPNFV open framework. This NaaS architecture can be instantiated according to three deployment models allowing application service providers (OTTs) and application services themselves to request specific network services from a network provider within a NaaS model. Therefore, we propose to demonstrate the feasibility of NaaS architecture deployment models with a focus on an “on-demand dynamic model” to highlight the offered dynamicity and easy application-to-network interactions. We have chosen to illustrate the deployment models with a WebRTC OTT application and showcase the on-demand dynamic deployment of virtual network functions, mainly TURN server. Because of time-sensitivity of these communication services, we have relied on container-based (Docker type) instead of virtual machine-based network functions virtualization.

Several frameworks have already been proposed to simplify the development of context-aware applications. These frameworks are focused on collecting and publishing contextual data, and on providing common semantics, definitions and representations of these data. This implies that applications share the same semantics, which limits the range of use cases where a framework can be used since that assumption induces a strong coupling between context management and application logic. This article proposes a framework that decouples context management from application business logic. The aim is to reduce the overhead for applications that run on resource-limited devices while still providing efficient mechanisms to support context-awareness and behavior adaptation. This framework implements an innovative approach that involves third parties in the process of context processing definition by structuring it in atomic functions, and describing it with an XML-based programming language. Its implementation and evaluation demonstrates the benefits, in terms of flexibility, of using trusted design patterns from software engineering for developing context-aware application.

In pervasive environments, end-users have heterogeneous devices to access their different services. These services are usually distributed over different devices and each service should be able to run in the most appropriate device. However, current technologies do not address the integration between these services and as a consequence the end user does not have the possibility to access the services in an optimal way. In this paper, we define and implement new mechanisms that enable a seamless integration of a service in the end-user pervasive environment. First, these mechanisms enable the end-user to personalize his/her pervasive environment by running each functionality in the most suited (preferred) device, and then to make these services communicate with each other. The specificity of our approach is that we split each application into independent functionalities, and then, we define and implement on the end-user devices a distributed mechanism that detects automatically semantic compatibilities between these functionalities.

The main aim of Enterprise Architecture (EA) is to master the development and the evolutions of Information Systems (IS). The EA process consists in designing on several views the IS target architecture, according to the company strategy. The business view represents the target organization of the considered company. The functional view focuses on the target functional architecture of the considered IS. In this paper, we propose a new formal solution to analyze the consistency between the target functional view and the target business view of telecom services. This solution is based on the definition of a strategic alignment of the target functional view with the target business view. Alignment is illustrated with a real case study achieved with Orange - France Telecom on their messaging service. An alignment measure completing this analysis provides an estimation of the gap between a target functional view and a target business view.

Widget aggregators such as iGoogle and Netvibes are broadly adopted by the mass market. They enable end-users to personalize their environment with their preferred services (Widgets). However, the usage in an enterprise context is not yet investigated. In this paper, we firstly show that in addition to personalization capability, the integration of business processes should be considered. Secondly, we propose a new Widget aggregator that enables the end-user to personalize a business process by chaining Widgets according to his/her needs and habits. Thirdly, we introduce a new approach for specifying an end-user process; an approach which enables even ordinary end-users, without computing skills, to define their processes. Finally, we validate these concepts by implementing and testing a prototype. As a consequence, this work does not only impact Widget aggregators, but it also innovates in end-user service creation research by proposing an intuitive tool, understandable even by ordinary end-users, for specifying their processes (composite services).

In this paper, we investigate the various service composition mechanisms and provide the impact of each of them on user-centric service development issues. We classify service composition mechanisms into three categories: automatic service composition, semi-automatic service composition, and static service composition. As services are today mainly driven by the user's needs, the following survey essentially focus on automatic service composition and semi-automatic service composition. This enables users to conceive their own personalized applications.

In this paper a new algorithm to compute the component tree is presented. As compared to the state-of-the-art, this algorithm does not use excessive memory and is able to work efficiently on images whose values are highly quantized or even with images having floating values. We also describe how it can be applied to astronomical data to identify relevant objects.

Reusing service capabilities to implement different integrated services in Next Generation networks (NGN) provides flexible and open service architecture capable of creating innovative services that do not need to be standardized and are based on the standardized service capabilities. In this architecture, invoking each integrated service may provoke the invocation of multiple service capabilities. The service architecture must therefore provide a mechanism to manage the interactions and the incompatibilities that may occur between these service capability invocations. Due to the shortcomings in the NGN service architecture domain for defining such mechanisms, we define in this paper, new architectural concepts regarding the implementation of a service capability interaction manager as well as the functionalities that this new entity must provide to avoid conflicts between service capability interactions in order to implement integrated services based on the standardized service capabilities.

This paper discusses the impacts of the emerging multimedia voice and data services on telecom intelligence distribution model. If the usual switching model and Internet model are insufficient for these services, the NGN model provides a good starting point. However, even NGN model presents some lacks on intelligence distribution aspects. Based on the existing models, we suggest here a generic architectural framework to position various functions needed for multimedia services. This framework is illustrated with concrete service examples, defined, developed and trialed in France Telecom R&D labs on a complete SIP architecture.