Andreas Georgakopoulos

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.

5G Mobile: Spectrum Broadening to Higher-Frequency Bands to Support High Data Rates

Next-generation [fifth-generation (5G)] mobile systems are broadening their spectrum to higher-frequency bands (above 6 GHz) to support a high data rate up to multigigabits per second. In this article, we have two main contributions to higher-frequency communications. First, we summarize the candidate frequency bands that are promising for 5G research, including licensed and unlicensed frequency bands. Second, a new network architecture for higher-frequency communications is proposed, which is featured with load-centric backhauling (LCB), multiple-frequency transmission, and intelligent control techniques.

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.

Intelligent 5G Networks: Managing 5G Wireless\/Mobile Broadband

Today there are forceful work streams that aim at realizing the fifth generation of wireless/mobile broadband (5G WMB). The work is driven by a framework that consists of three main requirements and two main sets of technology trends. This article presents the framework with the aim of contributing to the solidification of the technological foundations and longevity of 5G WMB systems. The requirements call for the proper provisioning of a large and rapidly expanding set of applications/services, the higher valorization of the infrastructure, and a drastic improvement of the energy efficiency. As will be explained, these requirements fulfill the need for fast and reliable service deployment, offering all types of relevant quality of service (QoS)/quality of experience (QoE), handling demanding and changing contexts of operation (exploding user-data/signaling traffic volumes and diverse mobility/radio conditions), providing means for the higher monetization of service provision, and drastically improving the cost efficiency. In parallel, the first set of technology trends includes the expansion of the WMB infrastructure features in terms of a new multiservice radio interface, networking options, and ways of architecting the system due to the introduction of the software-defined networking (SDN) and network function virtualization (NFV) concepts. There is also the trend of becoming more of a cloud platform instead of being a mere communication system. The importance of advanced management intelligence is also stressed in this article.

Cognitive Networks for Future Internet: Status and Emerging Challenges

This work provided an overview of the cognitive networks and systems for a wireless FI by considering the current status and looking forward at the emerging challenges. Emphasis was placed on the opportunistic networking paradigm to provide an insight on research regarding operator-governed ONs that are assumed to be coordinated extension of the infrastructure. For the coordination of operator-governed ONs, cognitive management entities are introduced. Moreover, further emphasis was placed on an operator-governed, end-to-end, autonomic, joint network and services management, which was elaborated as a part of this work. Network and services management is enabled through the definition of a UMF, which has a main goal to unify and federate various research outcomes and will advance the routine management tasks to the level of governance of the entire network.semantic.

FANTASTIC-5G: flexible air interface for scalable service delivery within wireless communication networks of the 5th generation

5th generation mobile networks will have to cope with a high degree of heterogeneity in terms of services, mobility, number of devices and so on. Thus, diverse and often contradicting key performance indicators need to be supported, but having multiple radio access technologies for multi-service support below 6i¾źGHz will be too costly. FANTASTIC-5G will develop a new multi-service air interface through a modular design. To allow the system to adapt to the anticipated heterogeneity, some properties need to be pursued, like simplicity, flexibility, scalability, versatility, efficiency and future proofness. Based on these properties, a selected set of use cases and link and network design will be presented. The paper will also comprise validation and system level simulations through some indicative results and will conclude with the overall impact to 5G standardisation. Copyright

Cognitive cloud-oriented wireless networks for the Future Internet

It is expected that the wireless world will migrate towards an era that will comprise more local/ temporary structures for the provision of services. A networking paradigm towards this direction is the opportunistic networking. Operator-governed ONs are dynamically created, temporary, coordinated extensions of the infrastructure. Operator governance is being realized through the use of Cognitive Management Systems which acquire the context, policies and profiles of the environment and make decisions on the creation of opportunistic networks. The paper presents an approach for exploiting such ONs in order to extend the capacity in wireless access and backhaul segments for efficient application provisioning, as well as an evaluation of indicative test cases as a proof of concept of the aforementioned approach. All these scenarios will enable the cognitive cloud-oriented vision of wireless networks for efficient application provisioning in the Future Internet era.

Resource allocation to femtocells for coordinated capacity expansion of wireless access infrastructures

As the Internet has penetrated everyday life, more and more users will demand high-quality services. However, the Internet was not designed to handle such heavy usage. Thus, networks need to be enhanced in order to deal with the increased traffic. In this study, the use of opportunistic networks (ONs) is studied. ONs are operator-governed, coordinated extensions of the infrastructure and are created dynamically for a limited time frame. The problem studied is the capacity extension of congested infrastructure via resource allocation to femtocells. More specifically, a macro base station (BS) is considered with deployed femtocells within its area. As soon as a problematic situation is discovered, the congested BS notifies the network management entity which will determine the solution method. In our case, a proportion of terminals that cause the congestion will be offloaded to the nearby femtocells relieving the macro BS. This is achieved through two approaches: a greedy algorithm that allocates the minimum possible power level to femtocells in order to acquire as much terminals as possible, and an energy-efficient algorithm that assigns the minimum possible power level to the femtocells that are required to cover specific terminals. Femtocells that are not needed are switched off.

Technical challenges for merging opportunistic networks with respective cognitive management systems in the Future Internet

The dawn of the Future Internet (FI) era poses new requirements to modern communication networks namely, the demand for new applications/ services, the support for diversified services, the expanded use of wireless access and the need for increased efficiency in resource provisioning and utilization. In this paper we propose a solution to address these requirements. In particular, the proposed solution is based on (i) opportunistic networks, which can be seen as operator-governed, temporary and probably infrastructure-less extensions of the infrastructure-based network, (ii) cognitive systems both for managing the opportunistic networks and for coordinating with the infrastructure, and (iii) control channels for the cooperation of the cognitive management systems. We advocate that the adoption of such a solution will bring about enhanced wireless service provision and extended access capabilities for the Future Internet, through higher resource utilization, lower costs, and management decisions with a larger “green” footprint.

Multi-RAT Dynamic Spectrum Access for 5G Heterogeneous Networks: The SPEED-5G Approach

Research and development of technologies that address the challenges of predicted growth in mobile connections and traffic volume is well known. A major challenge is the cost of meeting the objective, in terms of both infrastructure and deployment. Today, lack of dynamic control across wireless network resources is leading to unbalanced spectrum loads and a perceived capacity bottleneck. The solutions proposed by SPEED-5G through extended dynamic spectrum access (eDSA) address traffic allocation over heterogeneous wireless technologies, better load balancing across available spectrum bands, and capacity boosting through aggregation of available resources while ensuring fair coexistence. The objective of this article is to present a new framework for MAC and RRM layers for supporting eDSA and requirements of the next-generation networks.