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Longitudinal research is a unique research method that allows studying changes in individuals over time and how these changes vary within and across individuals. The goal of this entry is to give an overview about longitudinal research. The first part defines longitudinal research and discusses different perspectives of longitudinal change. The second part presents longitudinal research designs as a function of the temporal design. Traditional longitudinal research designs focus on developmental change, whereas intensive longitudinal research designs aim to capture short‐term dynamic processes. The third part discusses the diary method and ambulatory assessment as two examples of intensive longitudinal research methods that allow studying processes in daily life. The final part presents the measurement‐burst design that combines more traditional and intensive longitudinal research designs in an integrative way.

Cognitive methods refer to research approaches that incorporate the understanding of cognitive processing and individual differences in cognitive performance of individuals. The goal of this entry is to give an overview about different cognitive methods and discuss their application for personality science. The first part argues for the importance of cognitive methods in personality research. The second part defines different cognitive processes such as accessibility, attention, executive functions, implicit self‐attitudes, and semantic priming. What follows is a discussion of the assessment of these processes in personality research. The final part discusses the integration of personality and cognitive processes.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., This paper proposes an architecture framework for the realization of on-demand satellite network slicing that is built on the introduction of Software Defined Networking (SDN) and Network Function Virtualization (NFV) technologies. In this way, service delivery with satellite networks is shifted from a network for connectivity model to a network for service model with a high degree of service customization and adaptability, including satellite bandwidth on-demand. Under this framework, we study the resource orchestration of satellite network services by formulating the on-demand network slicing as an optimization problem that provides flexible service chaining and provisioning taking into account diversified service requirements. The objective is to determine the optimal resource allocation for supporting a satellite network slice that minimizes resources consumption while meeting service specification requirements such as the end-to-end delay., Peer Reviewed, Postprint (author's final draft)

©2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Radio Access Network (RAN) slicing is a key technology, based on Software Defined Networks (SDN) and Network Function Virtualization (NFV), which aims at providing a more efficient utilization of the available network resources and the reduction of the operational costs. In that respect, in this paper a novel virtualized WiFi network hypervisor is presented. This new hypervisor, based on a time variant radio resource sharing mechanism named Weighted Air-Time Deficit Round Robin (WADRR), is able to follow the dynamicity of the traffic variations seen by the different tenants located to the network Access Points (APs). It will be shown that the proposed WADRR hypervisor is able to dynamically assign the appropriate resources per tenant in every AP of the network, according to its specific traffic requirements. To this end, all the network APs are instructed by a controller which is responsible of guaranteeing, on average (long term perspective) and over the whole network, the accomplishment of the tenant's Service Level Agreement (SLA) target, while satisfying the short term traffic requests in the individual network APs. The correct behavior of the proposed algorithm has been validated through both simulations and in a real SDN-NFV platform build upon the 5G-EmPOWER test-bed., Peer Reviewed, Postprint (published version)

The orchestration of network services is a well investigated problem. Standards and recommendation have been produced by ETSI and IETF while a significant body of scientific literature can be found exploring both the theoretical and practical aspects of the problem. Likewise several open–source as well as proprietary tools for network service orchestration are already available. Nevertheless, in most of these cases network services can only be provisioned across a single administrative domain effectively preventing end–to–end network service delivery across multiple Infrastructure Providers (InP). In this paper we present X–MANO, a cross–domain network service orchestration framework consisting in an inter–domain confidentially–presenting federation interface and in an information model for multi– domain network service life–cycle programmability. X–MANO is effectively deployment–agnostic and can be used in hierarchical, peer–to–peer and cascading (or recursive) configuration. We validate X–MANO trough a proof–of–concept implementation over a multi–domain testbed. Finally, we release all the code under a permissive APACHE 2.0 license making it available to researchers and practitioners., Peer Reviewed, Postprint (published version)

The exponential growth of mobile data traffic still remains an important challenge for the mobile network operators. In response, the 5G scene needs to couple fast connectivity and optimized spectrum usage with cloud networking and high processing power, optimally combined in a converged environment. In this paper, we investigate two 5G research projects; SESAME [1] and COHERENT [2]. We consider the proposed 5G architectures and the corresponding key network components, in order to highlight the common aspects towards the 5G architecture design., Peer Reviewed, Postprint (published version)

In this manuscript, we present the main concepts of the 5G-PPP SESAME project dedicated to the implementation of Cloud-Enabled Small Cells (CESCs), able to support edge cloud computing in a multi-tenant, multiservice ecosystem. More particularly, we give a preview of the SESAME concept at the component/sub-system, system and operation level. At the component/sub-system level, we detail our plan to deploy multi-operator enabled small cells, enhanced with a virtualised execution platform for 5G. At the system level, we present the envisaged architecture to manage and control the cloud-enabled small cell infrastructure. Finally, at the operation level, we explain the potential advantages of adopting the SESAME concept on the 5G access networks., Peer Reviewed, Postprint (published version)

Current trends in broadband mobile networks are addressed towards the placement of different capabilities at the edge of the mobile network in a centralised way. On one hand, the split of the eNB between baseband processing units and remote radio headers makes it possible to process some of the protocols in centralised premises, likely with virtualised resources. On the other hand, mobile edge computing makes use of processing and storage capabilities close to the air interface in order to deploy optimised services with minimum delay. The confluence of both trends is a hot topic in the definition of future 5G networks. The full centralisation of both technologies in cloud data centres imposes stringent requirements to the fronthaul connections in terms of throughput and latency. Therefore, all those cells with limited network access would not be able to offer these types of services. This paper proposes a solution for these cases, based on the placement of processing and storage capabilities close to the remote units, which is especially well suited for the deployment of clusters of small cells. The proposed cloud-enabled small cells include a highly efficient microserver with a limited set of virtualised resources offered to the cluster of small cells. As a result, a light data centre is created and commonly used for deploying centralised eNB and mobile edge computing functionalities. The paper covers the proposed architecture, with special focus on the integration of both aspects, and possible scenarios of application., Peer Reviewed, Postprint (author's final draft)

Key features of satellite communications such as wide-scale coverage, broadcast/multicast support and high availability, together with significant amounts of new satellite capacity coming online, anticipate new opportunities for satellite communications services as an integral part within upcoming 5G systems. To materialize these opportunities, satellite communications services have to be provisioned and operated in a more flexible, agile and cost-effective manner than done today. In this context, this paper describes a solution for the virtualization and dynamic orchestration of satellite communication services that builds on the introduction of Software Defined Networking (SDN) and Network Function Virtualization (NFV) technologies within the satellite ground segment systems. Along with the description of the main system architecture traits, the flowchart of a general procedure for the dynamic instantiation of virtualized satellite networks on top of a SDN/NFV-enabled satellite ground segment system is provided. The paper also presents experimental results for the dynamic customization of satellite network services through the implementation of a set of virtualized satellite network functions that can be orchestrated over general purpose open virtual platforms., Peer Reviewed, Postprint (author's final draft)

Existing networks for public safety communications are mostly based on systems such as terrestrial trunked radio (TETRA), TETRAPOL and Project 25. These systems are mainly designed to support voice services. However, public safety communication networks are challenged to expand their scope way beyond their original functions toward more sophisticated devices and support new services including packet data communications. Therefore, governments, public safety agencies and research communities are continuously working together and are making significant progresses toward improving public safety communications capabilities. Next-generation mobile technologies are the enablers for meeting the new requirements of the public safety community. Public safety and commercial systems are typically designed and deployed to fulfill different needs and have different requirements, which are directly affecting the quality of service of the communications. The unique and vital nature of public safety affects the technical decisions that are necessary to guarantee connectivity for everyone, anywhere and anytime. For this reason, recent enhancements of the 4G long term evolution (LTE) in the field of public safety communications, such as device-to-device and group communications for mobiles in physical proximity, accrue a great opportunity to bring new services and a high-level of technological innovation to the public safety workers or first responders. We describe and analyze the evolution of public safety communication systems from the technical standpoint providing a complete overview of what is available in the market and a glimpse of future trends. Furthermore, we discuss the challenges to efficiently deploy, operate and interoperate present and future technologies for public safety communication networks and describe how these technologies can help public safety agencies to meet their expectations.