Vera Stavroulaki

5G on the Horizon: Key Challenges for the Radio-Access Network

Toward the fifth generation (5G) of wireless/mobile broadband, numerous devices and networks will be interconnected and traffic demand will constantly rise. Heterogeneity will also be a feature that is expected to characterize the emerging wireless world, as mixed usage of cells of diverse sizes and access points with different characteristics and technologies in an operating environment are necessary. Wireless networks pose specific requirements that need to be fulfilled. In this respect, approaches for introducing intelligence will be investigated by the research community. Intelligence shall provide energy- and cost-efficient solutions at which a certain application/service/quality provision is achieved. Particularly, the introduction of intelligence in heterogeneous network deployments and the cloud radio-access network (RAN) is investigated. Finally, elaboration on emerging enabling technologies for applying intelligence will focus on the recent concepts of software-defined networking (SDN) and network function virtualization (NFV). This article provided an overview for delivering intelligence toward the 5G of wireless/mobile broadband by taking into account the complex context of operation and essential requirements such as QoE, energy efficiency, cost efficiency, and resource efficiency.

Enabling smart cities through a cognitive management framework for the internet of things

The Internet of Things (IoT) is expected to substantially support sustainable development of future smart cities. This article identifies the main issues that may prevent IoT from playing this crucial role, such as the heterogeneity among connected objects and the unreliable nature of associated services. To solve these issues, a cognitive management framework for IoT is proposed, in which dynamically changing real-world objects are represented in a virtualized environment, and where cognition and proximity are used to select the most relevant objects for the purpose of an application in an intelligent and autonomic way. Part of the framework is instantiated in terms of building blocks and demonstrated through a smart city scenario that horizontally spans several application domains. This preliminary proof of concept reveals the high potential that self-reconfigurable IoT can achieve in the context of smart cities.

m@ANGEL: autonomic management platform for seamless cognitive connectivity to the mobile internet

B3G wireless access infrastructures can be realized through the concept of cognitive networks. In a B3G context, a network operator will rely on various alternate wireless access technologies, for realizing the appropriate business goals, such as capacity and QoS levels. Cognitive wireless access networks dynamically change their configuration, and in this respect the radio access technologies and spectrum used at the physical and MAC layers, in order to adapt to environment conditions. A cognitive infrastructure consists of reconfigurable elements and intelligent management functionality. This article focuses on the management part. We present a platform, called m@ANGEL, which adheres to autonomic computing principles, and aims at the provision of seamless cognitive connectivity to the mobile Internet. Our work starts from a business level view of cognitive wireless access networks. Technical requirements for m@ANGEL are identified, and the architecture of the platform is described. Moreover, the article describes the functionality and engineering challenges of the m@ANGEL components, which provide the means for monitoring, discovery, context acquisition, description of profiles/goals/agreements, resource and service brokerage, configuration negotiation, selection, and implementation. Finally, concluding remarks are drawn, and issues for the next phases of our work are identified

Virtualization and Cognitive Management of Real World Objects in the Internet of Things

This paper presents a framework for the virtualization of real world objects and the cognitive management of their virtual counterparts. The framework consists of three levels of functionality and each level comprises cognitive entities that provide the means for self-management and learning, allowing for smart, flexible applications and objects. The presented framework enables the abstraction of the heterogeneity that derives from the vast amount of diverse objects/devices, while enhancing reliability and facilitates the consideration of the views of various users/stakeholders (owners of objects & communication means) for ensuring proper application provision, business integrity and, therefore, maximization of exploitation opportunities. The paper also presents a corresponding prototype that has been developed for the validation of the proposed approach, in a real-life fire detection scenario in a Smart Home.

Cognitive control channels: from concept to identification of implementation options

Recent effort related to cognitive radio systems has lead to an in-depth analysis of context information management and exploitation based on a cognitive control channel for enhancement of management needed for, say, suitable link selection in a heterogeneous radio framework, dynamic radio resource management, and distributed sensing. Concerning the actual implementation of such a CCC, the focus was recently moved toward an in-band solution, where the information is transported building on existing radio access technologies. In this scope, this article illustrates relevant technical scenarios in which CCCs can be exploited and outlines a set of derived system requirements. The article provides an overview of various possible RAT independent and dependent implementation options, such as Diameter, distributed agents, 3GPP radio resource control (RRC) mechanisms, IEEE 802.21, IEEE 802.11, WiMedia UWB, and Bluetooth. The advantages and drawbacks of the various options are discussed.

Issues in introducing resource brokerage functionality in B3G composite radio environments

This article identifies and discusses problems that should be addressed for introducing resource brokerage functionality in beyond-third-generation wireless environments. Resource brokerage is a capability required by the B3G concept. It enables cooperation between NPs in handling new service area conditions that originate in a network of the B3G infrastructure. The article starts from a business case that justifies the need for RB functionality. Its integration in management systems for composite radio environments (MS-CRE) is also presented. Subsequently, there is a presentation of the RB process interfaces, as well as the approach taken to decompose the overall process into smaller problems. Finally, there is a description of the individual tasks: selection of QoS levels, demand volume, and prices.

Cognitive Management for the Internet of Things: A Framework for Enabling Autonomous Applications

The handling of the number of objects that will be part of the Internet of Things (IoT) and the various networking technologies used for their interconnection requires suitable architecture and technological foundations. Despite significant work on architectures and test facilities for the IoT, there is still a lack of management functionality to overcome the technological heterogeneity and complexity of the underlying networks and IoT infrastructure, so as to enhance context/situational-awareness, reliability, and energy-efficiency of IoT applications. This article presents a cognitive management framework for the IoT aiming to address these issues, comprising three levels of functionality: virtual objects (VOs), composite VOs (CVOs), and service levels. Cognitive entities at all levels provide the means for self-management (configuration, optimization, and healing) and learning. Three fundamental processes of this framework are presented: dynamic CVO creation, knowledge-based CVO instantiation, and CVO self-healing. A first prototype implementation of this framework and corresponding derived results are presented.

Smart management of D2D constructs: an experiment-based approach

This article considers the concept of device-to- device communications for the resolution of persistent issues in mobile networks. Specifically, two scenarios are described, the opportunistic coverage expansion of the infrastructure, where an access point transits to offline mode (and hence its terminals shall exploit the presence of neighboring devices in order to reroute their traffic to alternative APs), as well as the opportunistic capacity expansion scenario where an AP faces congestion issues due to the excessive traffic of its terminals or the use of an obsolete RAT with low capacity. In the same manner, part of the traffic shall be offloaded to alternative APs through the creation of D2D links with neighboring devices. In order to realize the proposed solutions, the network elements exchange information regarding their capabilities and their status so as to identify the best path from all the potential ones. Therefore, control channels for cognitive radio systems will be utilized since the information that is conveyed through them comprises information from all the layers of the protocol stack. Furthermore, the article focuses on the coverage expansion scenario, which is implemented at the w.iLab-t testbed. In order to realize the D2D constructs, the devices of the testbed will be configured to communicate through WiFi technology, and specifically the 802.11s standard for wireless mesh networks, in order to enable multihop communications. In this respect, the D2D constructs that will be created are mesh networks that comprise the problematic terminals, their neighboring terminals that offload their traffic, and the APs that receive the traffic. In order to evaluate the proposed solution, the signaling loads of the conveyed messages are measured, as well as the performance of the mesh network that is created after the solution enforcement through the use of a ping, a file transfer, and a video streaming application.

A Model-Based Security Toolkit for the Internet of Things

The control and protection of user data is a very important aspect in the design and deployment of the Internet of Things (IoT). The heterogeneity of the IoT technologies, the number of the participating devices and systems, and the different types of users and roles create important challenges in the IoT context. In particular, requirements of scalability, interoperability and privacy are difficult to address even with the considerable amount of existing work both in the research and standardization community. In this paper we propose a Model-based Security Toolkit, which is integrated in a management framework for IoT devices, and supports specification and efficient evaluation of security policies to enable the protection of user data. Our framework is applied to a Smart City scenario in order to demonstrate its feasibility and performance.

Management System for Terminals in the Wireless B3G World

In the era of wireless communications, Beyond the 3rd Generation (B3G), a network operator (NO) should satisfy numerous requirements, namely, personalisation, context awareness, always best connectivity, ubiquitous service provision and seamless mobility. A NO can efficiently satisfy the requirements by relying on the different radio networks of its heterogeneous infrastructure, and potentially on other cooperating networks. In this respect, the NO should possess advanced management mechanisms for driving its users to the most appropriate networks that satisfy the requirements. The presentation of such a management system is the specific contribution of this paper. The system is called Reconfigurable Terminal Management System (RTMS). In general, it provides the means for profile modelling, the acquisition of monitoring/discovery/context information, and the negotiation and selection of configurations, based on information deriving from policies, as well as the profiles and the context. Our work focuses on the role and the information of the components of the RTMS. Concrete functionality for accomplishing the role is also presented. Nevertheless, the system is open to the integration of alternate functionality. Our discussion includes a business case that presents in high-level terms the role of the management system, a detailed description of the components of the management system and results that show the efficiency of the management schemes. A summary and further research challenges, conclude this article.