Zachos Boufidis

Evolution of Wireless Communication Systems Towards Autonomously Managed, Cognitive Radio Functionalities

This contribution presents key functionalities and design approaches of a distributed system architecture as it is studied in the framework of the European E2R II project. An emphasis is laid on policy based self-governance, distributed reconfiguration concepts and corresponding cognitive support functionalities; this support is necessary to assure context awareness in the equipment in order to facilitate (enable) distributed decision making. The idea is to distribute decision making functionalities among network and user equipment elements in order to (i) limit the required calculation complexity on the network and user side for the determination of the optimum resource selection strategy, (ii) increase the reactivity of the equipment to any context change minimizing the required amount of human interaction and (iii) minimize the signaling overhead by broadcasting generic policy rules applicable to all users instead of targeting a user-by-user based reconfiguration approach. A simple use case illustrates how Game Theoretic tools can be used in order to derive suitable policies and how to perform decisions.

End-to-End Architecture for Cognitive Reconfigurable Wireless Networks

Reconfigurability is set to be an important facet in the evolving world of mobile and wireless communications, through which technologies such as cognitive radio are greatly facilitated. Given advances in the scope and applicability of software functionalities, reconfigurability is increasingly becoming possible at many layers of the protocol stack which would until recently have been maintained only by intransigent fixed hardware components. Moreover, given the complexity and range of emerging reconfiguration possibilities, it would be useful for devices and networks to be able to efficiently partake in reconfiguration procedures with reduced-or even zero-human input. This would maximise the realisation of potential performance improvements through reconfiguration-associated technologies. This paper therefore discusses the development of an end-to-end system architecture that incorporates cognition and autonomics aspects into reconfiguration procedures. The architecture, its overall context, and its mapping to the emerging 3GPP System Architecture Evolution (SAE), are discussed.

Network support modeling, architecture, and security considerations for composite reconfigurable environments

Emerging radio access technologies such as wireless personal and metropolitan area networks and digital broadcasting are a new era for wireless communications. These standards aim at complementing existing cellular/Wi-Fi networks in order to offer a wide range of available access modes to mobile terminals. Multiradio wireless systems referred to as composite radio access networks, bear diverse capabilities, with the optimal radio being invoked to perform a specific set of functions. Composite reconfigurable radio networks support the collaboration of a wide range of heterogeneous radio access technologies under a single or multiple administrative boundaries, adding further intelligence to the way devices attach to and switch between networks spatially and temporally. The EU End-to-End Reconfigurability (E2R) research project envisages composite reconfigurable radio networks coupled with legacy as well as evolved core network architectures, yielding simpler and flexible configurations for reduced latencies, autonomic operation, and adaptive functionality. This article presents a cohesive model for controlling and managing such networks, elaborates on the constituent functional entities, and maps this model to two-tier network support architecture. Finally, key security issues for software download over reconfigurable radios and systems are identified and solutions for software certification and authorization as well as for the authentication of roaming terminals are proposed.

Architecture and signaling protocol for migration to cognitive reconfigurable post-3G mobile systems

The advent of software-defined radio products and recent advances in cognitive radio research will facilitate the preservation or even improvement of user perception in volatile radio conditions while optimizing the use of network resources. Based on cognition techniques, the autonomic communication paradigm attempts to pave the way towards self-governed systems that will alleviate the shortcomings of present remotely managed user devices. This article identifies the challenges for such cognitive reconfigurable systems and introduces CORPS, a new end-to-end architecture that unifies software and cognitive radio themes enriched by self-ware capabilities. The manuscript discusses the adopted network-agnostic protocol-independent modeling approach, which is in line with best common practices in the industry, and presents the system architecture in terms of functional specification and UML modeling. Next, the CORPS functional architecture is mapped to the evolved-UMTS system under development in 3GPP. Finally, the paper proposes and evaluates CREST, a novel signaling protocol for improving the quality of service of existing bearers in a post-3G network through radio-access-technology switching and coordinated dynamic spectrum access.

Towards Future Internet services through crowdsourcing-based sensor platforms

Crowdsourcing initiatives accommodate the trend to transition from mere resource pooling, which has been successfully applied in technical domains such as grid computing and cognitive radio networks, to human resource pooling, with people contributing to a common purpose. Future Internet emerges as a paradigm that will incorporate crowdsourcing in many forms, with participatory mobile sensor networks being a prominent representative. In such networks, citizens carry small portable devices that provide sensor readings on demand, for example, for air quality monitoring. Whereas a multiplicity of research and industrial efforts has tackled the issue of connecting sensors and producing meaningful data over a plethora of deployed sensors, few initiatives have progressed beyond field-testing, partially due to underestimating the importance of service engineering aspects. This note aims at highlighting the objectives to be fulfilled and the necessary capabilities of sensor platforms towards the provision of Future Internet services built on top of crowdsourcing facilities.

Towards the Functional Enhancement of 3GPP Networks with Reconfiguration Capacities

Over the last decade, several wireless access systems, such as broadband WLAN and WMAN (e.g., IEEE 802.11 and 802.16), broadcast systems (e.g., DAB, DVB-T) and short-range connectivity systems (e.g., Bluetooth, UWB), have emerged to complement existing second (2G) and third (3G) generation cellular systems. The common objective is to migrate to a flexible connectivity platform that will support the disparate requirements of mobile applications in the next-generation era, commonly referred to as 4G. To achieve a versatile multi-radio and multi-protocol access from mobile devices of limited resources in 4G, the original software-radio concept has evolved into across-the-board reconfiguration, which includes not only radio-specific functionalities but supports also the dynamic modification of the entire protocol stack. The present article clarifies the fundamental aspects of reconfiguration and points out the shortcomings of current standards for describing the reconfiguration capabilities (i.e., metadata about the feasible alternative configurations) of mobile network elements. An object-oriented model for reconfiguration metadata is introduced and isomorphically mapped to an RDF vocabulary, which is used to describe reconfigurable protocol stacks as defined for UMTS/WLAN mobile devices. The associated description languages and formats are presented and evaluated with regard to their applicability and suitability for this task and the criteria for choosing one are identified and detailed. Next, the article proposes a novel generic modular architecture for reconfiguration support in 4G mobile networks and elaborates on its functional components. We investigate the integration of our logical architecture in the 3GPP mobile network architecture and illustrate the allocation of its functional elements over the logical domains of 3GPP system Release 6 and onwards. Furthermore, we show the signaling between terminal-side and network-side architecture components for software download and protocol stack reconfiguration. Finally, we summarize our experience gained from a prototype implementation, evaluate the total signaling cost, and give directions for future work.