We study completely independent spanning trees (CIST), i.e. , trees that are both edge-disjoint and internally vertex-disjoint, in split graphs. We establish a correspondence between the existence of CIST in a split graph and some types of hypergraph colorings (panchromatic and bipanchromatic colorings) of its associated hypergraph, allowing us to obtain lower and upper bounds on the number of CIST. Using these relations, we prove that the problem of the existence of two CIST in a split graph is NP-complete. Finally, we formulate a conjecture on the bipanchromatic number of a hypergraph related to the results obtained for the number of CIST.

Given a non-decreasing sequence S=(s1,s2,…,sk) of positive integers, an S-packing coloring of a graph G is a partition of the vertex set of G into k subsets {V1,V2,…,Vk} such that for each 1≤i≤k, the distance between any two distinct vertices u and v in Vi is at least si+1. In this paper, we study the problem of S-packing coloring of cubic Halin graphs, and we prove that every cubic Halin graph is (1,1,2,3)-packing colorable. In addition, we prove that such graphs are (1,2,2,2,2,2)-packing colorable.

Summary In this article, we present two deterministic leader election algorithms for programmable matter on the face‐centered cubic grid. The face‐centered cubic grid is a three‐dimensional 12‐regular infinite grid that represents an optimal way to pack spheres (i.e., spherical particles or modules in the context of the programmable matter) in the three‐dimensional space. While the first leader election algorithm requires a strong hypothesis about the initial configuration of the particles and no hypothesis on the system configurations that the particles are forming, the second one requires fewer hypothesis about the initial configuration of the particles but does not work for all possible particles' arrangement. We also describe a way to compute and assign ℓ‐local identifiers to the particles in this grid with a memory space not dependent on the number of particles. A ℓ‐local identifier is a variable assigned to each particle in such a way that particles at distance at most ℓ each have a different identifier.

Energy optimization is essential in IoT environments due to energy constraints for some IoT components. In fact, energy consumption has a direct impact on IoT system lifetime, which represents an important Quality of Service (QoS) parameter for IoT environments. In order to extend the IoT system lifetime, energy consumption optimization should be considered in several IoT components. In this paper, we specify an energy self-optimizing mechanism allowing to minimize data transmission energy consumption of IoT objects. This mechanism enables selecting specific objects to send the desired data while minimizing the energy consumed for the corresponding communication. Our proposal is made of a Mamdani Fuzzy Logic based system considering different IoT environment parameters enabling IoT objects evaluation. In this context, three input parameters (Distance between the IoT object collecting the data and the coordinator, Residual Energy in the IoT object, Precision of the information collected by the IoT object) and a single computed output parameter (IoT object chance) are used in our proposed Fuzzy Logic system. The obtained IoT objects chances enable choosing the best IoT object(s) to retrieve the requested data while maximizing the corresponding IoT system lifetime.

Access Control is an important security service that should be considered in IoT environments in order to offer reliable IoT services. Access control in IoT environments concerns not only the access of IoT users to IoT services and objects, but also the access of IoT objects to IoT gateways. In this paper, we specify an access control mechanism that considers the access of IoT objects to IoT gateways in order to enhance the reliability of IoT data provided by the IoT objects. Our proposed access control mechanism, called IoT-MAAC (Multi Attribute Access Control), allows retrieving requested data from the most reliable and secured IoT objects among the available objects in the IoT environments.

In the new technological era called the Internet of Things (IoT), people, machines and objects communicate with each other via the Internet by exchanging information. In this context, trust plays an important role and is considered as a key factor in the success of the IoT services expansion. IoT services and applications use in some cases data concerning the privacy of their users. Consequently, users should trust the entities exchanging their personal information. In this paper, we present a framework that evaluates the security trust level of IoT nodes based on a Fuzzy Logic model using different input parameters such as Device Physical Security, Device Security Level and Device Ownership Trust. The proposed Fuzzy Logic model evaluates a trust level for each node as an output. Then, based on the threshold defined by users, the best node(s) in terms of trust level, is/are selected to collect information, which could be critical and concern privacy protection. Thus, the IoT service users are able to play an active role in selecting the trusted nodes (trust level greater than the threshold) to collect their data.

We investigate the problem of computing Completely Independent Spanning Trees (CIST) under a practical approach. We aim to show that despite CISTs are very challenging to exhibit in some networks, they present a real interest in ad-hoc networks and can be computed to enhance the network robustness. We propose an original ILP formulation for CISTs and we show through simulation results on representative network models that several CISTs can be computed when the network density is sufficiently high. These results tend to reinforce the interest of CISTs for various network operations such as robustness, load-balancing, traffic splitting, . . . As an important point, our results show that both the density and the number of nodes have an impact on the number of CISTs that can be found on ad-hoc networks.

Today, the Cloud networking aspect is a critical factor for adopting the Cloud computing approach. The main drawback of Cloud networking consists in the lack of Quality of Service (QoS) guarantee and management in conformance with a corresponding Service Level Agreement (SLA). This paper presents a framework for resource allocation according to an end-to-end SLA established between a Cloud Service User (CSU) and several Cloud Service Providers (CSPs) in a Cloud networking environment. We focus on QoS parameters for Network as a Service (NaaS) and Infrastructure as a Service (IaaS) services. In addition, we propose algorithms for the best CSPs selection to allocate Virtual Machines (VMs) and network resources in inter-cloud broker and federation scenarios. Our objective is to minimize the cost while satisfying NaaS and IaaS QoS constraints. Moreover, we simulate our proposed Cloud networking architecture to provide videoconferencing and intensive computing applications with QoS guarantee. We observe that the broker architecture is the most interesting while ensuring QoS requirements.

Multi-path routing concept was largely exploited in wireless networks to provide benefits such as fault tolerance, load balancing, performance improvement in terms of latency, etc. In this paper, we propose a multi-path routing based protocol named MP-IMRR (Multi-path Intra-Mesh infrastructure Routing protocol) to improve our previously defined QoS based routing protocol for wireless mesh networks (i.e. IMRR). MP-IMRR is defined in order to achieve better reactivity and faster recovery from eventual route failures than the IMRR protocol by adopting the backup routes concept. Besides, given the complexity increase while considering network management systems, we adopt the autonomic computing paradigm to provide the IMRR routing protocol with self-configuring capabilities. We describe and analyze the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of IMRR self-configuring scheme and MP-IMRR routing protocol in case of route failures.

Today, cloud networking which is the ability to connect the user with his cloud services and to interconnect these services within an inter-cloud approach, is one of the recent research areas in the cloud computing research communities. The main drawback of cloud networking consists in the lack of Quality of Service (QoS) guarantee and management in conformance with a corresponding Service Level Agreement (SLA). Several research works have been proposed for the SLA establishing in cloud computing, but not in cloud networking. In this paper, we propose an architecture for self-establishing an end-to-end service level agreement between a Cloud Service User (CSU) and a Cloud Service Provider (CSP) in a cloud networking environment. We focus on QoS parameters for NaaS and IaaS services. The architecture ensures a self-establishing of the proposed SLA using autonomic cloud managers.