Lucio Studer Ferreira

Opportunistic management of spontaneous and heterogeneous wireless mesh networks [Accepted from Open Call]

In the traditional model for wireless mesh networks, a two-tiered architecture classifies nodes into mesh routers or clients. Such an approach, based on strong separation of roles, is interesting when an administrative entity deploys and controls the network. Nevertheless, in spontaneous and self-organized networks, where there is no administrative entity behind the network formation, this model does not hold anymore. In such a scenario the heterogeneity of nodes should be fully exploited in order to increase, as much as possible, network availability and usability. In this article we propose an approach for opportunistic wireless mesh network formation and maintenance that breaks the rigidness of the traditional architecture. We relax the role separation constraint and consider the case of spontaneous network formation relying on the concept of self-organization and collaboration. The main idea is to make the network take advantage of the specific resources and characteristics of the nodes in an opportunistic fashion. In our vision, any node (routers and clients) can perform any network functionality, if they can and if they wish.

Characterisation of Signal Penetration into Buildings for GSM and UMTS

A study of the extra signal attenuation due to building penetration associated to path loss from the base stations to mobile terminals, for different types of buildings and rooms is presented for GSM (900 and 1800 MHz) and UMTS. In this study, a statistical model for the attenuation penetration is developed, following the log-normal distribution, applied to a building classification, and supported on measurements of the actual systems under consideration, which can be used for radio network planning purposes. Different types of buildings (High-Integrated, High-Isolated, Low-Integrated, and Low-Isolated) and rooms (Indoor Light, Indoor, Deep Indoor) are considered. A study on the variation of the attenuation per floor, room and building type is performed. An average attenuation of 5.7 dB for GSM900 is observed, with a standard deviation of 11.1 dB.

OConS: Towards Open Connectivity Services in the Future Internet

The recent advances on networking technologies (both at the access and the core realms) together with the ever-increasing requirements of the end-users and their applications/services call for an open approach, yet with a clear migration strategy, so as to avoid the well-known shortcomings and limitations of clean-slate approaches. These requirements have streamlined the design of a novel (yet not revolutionary) architecture framework based on the identification of functional entities and their interfaces. The most distinguishing feature is its flexibility, allowing its adaptation to already existing protocols/technologies/algorithms as well as to novel solutions.

Energy-efficient radio resource management in self-organised multi-radio wireless mesh networks

Wireless mesh networks are an efficient and low-cost solution for providing last-mile broadband Internet access. They face numerous challenges related to intrinsic characteristics of the multi-hop environment and flow of traffic. An energy-efficient and load-aware strategy is proposed for the unified management of radio resources of multi-radio nodes, combining channel assignment, rate adaptation, power control and max-min fairness mechanisms. It exploits 100% of the network capacity, achieving the maximum throughput, minimising spectrum and power usage. For a network of 13 dual-radio mesh nodes based on IEEE 802.11a, by using OPNET Modeler, one concludes that 4 channels and a total transmitted power of 34.5 dBm are sufficient to achieve an aggregated throughput of 4.8 Mbps per mesh point.

User-centric analysis of perceived QoS in 4G IP mobile/wireless networks

This paper presents the emerging requirements users are imposing upon the evolving world of heterogeneous 4G mobile/wireless networks through their perception of final services. The mapping proposed in this paper groups together these user requirements in three main and distinguishable categories: service provision, connectivity, and adaptability and reconfigurability, by describing system concepts for each category from user terminal to network and services/applications.

An architecture to offer cloud-based radio access network as a service

This paper addresses the novel notion of offering a radio access network as a service. Its components may be instantiated on general purpose platforms with pooled resources (both radio and hardware ones) dimensioned on-demand, elastically and following the pay-per-use principle. A novel architecture is proposed that supports this concept. The architectures success is in its modularity, well-defined functional elements and clean separation between operational and control functions. By moving much processing traditionally located in hardware for computation in the cloud, it allows the optimisation of hardware utilization and reduction of deployment and operation costs. It enables operators to upgrade their network as well as quickly deploy and adapt resources to demand. Also, new players may easily enter the market, permitting a virtual network operator to provide connectivity to its users.

Open connectivity services for the future internet

In this paper we present an Open Connectivity Services architecture, which has been conceived such as to cope with the challenges posed by the Future Internet. By relying on currently working solutions and establishing a trustworthy migration strategy, the proposed architecture provides a flexible framework that supports both legacy and enhanced connectivity mechanisms. It is able to dynamically adapt the operation of the involved mechanisms according to the particular requirements of the services and applications. This open architecture is based on three main modules (information gathering, decision taking and decision enforcement) which mimic the basic functionalities of any connectivity mechanism. By having a common way of representing current and future mechanisms, the OConS operation eases the instantiation, launch and interconnection of mechanisms by the specified orchestration procedures. A challenging flash crowd scenario is presented for validation of the architecture, where enhanced connectivity mechanisms support both cloud networking and network of information use cases.

Parameters for the Definition of Scenarios for CRRM Performance Evaluation

This paper addresses the RRM and CRRM reference scenarios state of the art. Many researchers use simulation tools for their work, using different approaches and scenarios, disabling the possibility to evaluate and compare results among them. Thus, this paper besides pointing out the different activities on reference scenarios, proposes a set of scenarios for RRM and CRRM for GERAN, UTRAN and WLAN. This paper constitutes a first approach to the identification of key parameters related with RRM/CRRM performance evaluation

Service for Management of Connectivity in Spontaneous Community-Based Wireless Mesh Networks

Spontaneously deployed wireless mesh networks raise challenging connectivity aspects. Based on an organizational framework and on an open connectivity service architecture, an opportunistic resources management service is proposed, which exploits network conditions and node capabilities to improve connectivity. This service is able to orchestrate adequate connectivity mechanisms, such as access provisioning, mesh forwarding and Internet gateway ones, in multi-radio nodes. The service is evaluated for a spontaneous neighbourhood community-based Wireless Mesh Network scenario, where a flash crowd of end-users with heterogeneous terminals is explored. It is shown that network performance is improved, increasing overall coverage and capacity.

Radio network aspects

Publisher Summary This chapter reviews the mobile radio access network reference scenarios (MORANS)—used to study the performance of the radio cellular networks related to UMTS and the methodologies for the radio network performance evaluation, including the theoretical connectivity models,. It discusses the techniques for radio network optimization such as the packet scheduling for cellular systems or system capacity maximization through the use of multiple antennas. . In order to perform system simulations, reference values for the main parameters characterizing a WCDMA network, are required. MORANS is used for the identification of such parameters. The parameters are classified in two groups: the parameters whose value can be found in the specification documents, and the parameters with unspecified value requiring optimization. The estimated performance in the downlink of a WCDMA network can be evaluated by means of two dynamic system simulators. The chapter concludes by discussing important RRM procedures, simplified algorithms. Some of them are: call admission control, congestion control, and soft handover procedure.