On load balancing via switch migration in software-defined networking

Switch-controller assignment is an essential task in multi-controller software-defined networking. Static assignments are not practical because network dynamics are complex and difficult to predetermine. Since network load varies both in space and time, the mapping of switches to controllers should be adaptive to sudden changes in the network. To that end, switch migration plays an important role in maintaining dynamic switch-controller mapping. Migrating switches from overloaded to underloaded controllers brings flexibility and adaptability to the network but, at the same time, deciding which switches should be migrated to which controllers, while maintaining a balanced load in the network, is a challenging task. This work presents a heuristic approach with solution shaking to solve the switch migration problem. Shift and swap moves are incorporated within a search scheme. Every move is evaluated by how much benefititwillgivetoboththeimmigrationandoutmigrationcontrollers.Theexperimentalresultsshowthat theproposedapproachisabletooutweighthestate-of-artapproaches,andimprovetheloadbalancingresults up to≈ 14% in some scenarios when compared to the most recent approach. In addition, the results show that the proposed work is more robust to controller failure than the state-of-art methods.Portuguese Science and Technology Foundation (FCT) - UID/MULTI/00631/2019;info:eu-repo/semantics/publishedVersio

Interoperability in IoT through the semantic profiling of objects

The emergence of smarter and broader people-oriented IoT applications and services requires interoperability at both data and knowledge levels. However, although some semantic IoT architectures have been proposed, achieving a high degree of interoperability requires dealing with a sea of non-integrated data, scattered across vertical silos. Also, these architectures do not fit into the machine-to-machine requirements, as data annotation has no knowledge on object interactions behind arriving data. This paper presents a vision of how to overcome these issues. More specifically, the semantic profiling of objects, through CoRE related standards, is envisaged as the key for data integration, allowing more powerful data annotation, validation, and reasoning. These are the key blocks for the development of intelligent applications.Portuguese Science and Technology Foundation (FCT) [UID/MULTI/00631/2013

A Multi-Objective Optimization Approach for Fault-Tolerance Provisioning in Multi-Radio Hybrid Wireless-Optical Broadband Access Networks

Wireless-optical broadband-access networks (WOBANs), currently being deployed at the access section, should integrate fault-tolerance in their design so that geographically continuous wireless coverage can be provided without service breaks. In this paper we propose a joint wireless and optical fault-tolerance planning approach for WOBANs having multiple radios in each router. The problem is formalized, as a multi-objective optimization problem, and a heuristic is proposed to solve this problem. Two fault-tolerance planning scenarios, where gateways are arranged differently in the risk groups, are analysed. It is shown that multi-radio routers can be exploited to improve the performance of WOBANs, providing wireless and optical fault-tolerance. Results also indicate that, when using our approach, a small increase in the number of radios can significantly decrease the total capacity required to provide any degree of fault-tolerance.This work was supported by the Foundation for Science and Technology from Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications) and by the project PTDC/EEA-TEL/71678/2006

A heuristic for fault-tolerance provisioning in multi-radio hybrid wireless-optical broadband access network

The wireless-optical broadband-access network (WOBAN) architecture has been proposed as a flexible and cost-effective solution for future access networks. However, for WOBANs to provide geographically continuous wireless coverage it is necessary to integrate fault-tolerance in the design of such networks. In this paper we develop a heuristic algorithm to solve the problem of planning a wireless and optical fault-tolerant multi-radio WOBAN, considering any fault-tolerance scenario (e.g. some nodes/links/region only), while making an efficient reuse of spectrum

Forwarding Repeated Game for End-to-End QoS Support in Fiber-Wireless Access Networks

Fiber-wireless (FiWi) access mesh networks have been proposed as flexible and cost-effective solutions for future access networks. However, for FiWi access mesh networks to provide end-to-end QoS guarantees to its customers, efficient QoS routing schemes and scheduling policies become necessary. Here we provide a model, using repeated game theory, that creates ground for scheduling policies to be implemented. That is, our framework provides insights into how much bandwidth a wireless router needs to share, for foreign traffic forwarding, so that services of local users and services of foreign users can all receive bandwidth in a balanced way. Some strategies were tested, under the developed model, to look for equilibrium states. The equilibrium strategies provide the means for QoS guarantees in FiWi access mesh networks, meaning that they can be used as a basis for scheduling policies.This work was supported by FCT (Foundation for Sci- ence and Technology) of Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications), research project PTDC/EEA-TEL/71678/2006, and by J. Coimbra’s Ph.D. grant SFRH/BD/37808/200

A bounded heuristic for collection-based routing in wireless sensor networks

Wireless sensor networks are used to monitor and control physical phenomena and to provide interaction between clients and the physical environment. Clients have been typically users or user applications, but next generation wireless sensor networks will also work in machine-to-machine scenarios where some nodes can be interested in some other nodes' data. These scenarios may run the risk of becoming overloaded with messaging, a pernicious fact in particular for constrained networks where both bandwidth and power supply are limited. Resource collections can be used in wireless sensor networks to improve bandwidth usage and to reduce energy consumption, reducing the overall number of notification packets and wrapping overhead, required for the delivery of sensor data. This article proposes a heuristic algorithm for the planning of both routing and collections, in wireless sensor networks. Results show that collections are always worthwhile, and that the heuristic is able to find feasible and cost effective solutions, approaching its lower bound.FCT from Portugal within the CEOT research center [UID/MULTI/00631/2013

Resource allocation model for sensor clouds under the sensing as a service paradigm

The Sensing as a Service is emerging as a new Internet of Things (IoT) business model for sensors and data sharing in the cloud. Under this paradigm, a resource allocation model for the assignment of both sensors and cloud resources to clients/applications is proposed. This model, contrarily to previous approaches, is adequate for emerging IoT Sensing as a Service business models supporting multi-sensing applications and mashups of Things in the cloud. A heuristic algorithm is also proposed having this model as a basis. Results show that the approach is able to incorporate strategies that lead to the allocation of fewer devices, while selecting the most adequate ones for application needs.FCT (Foundation for Science and Technology) from Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications) UID/MULTI/00631/2019info:eu-repo/semantics/publishedVersio

Resource design in constrained networks for network lifetime increase

As constrained "things" become increasingly integrated with the Internet and accessible for interactive communication, energy efficient ways to collect, aggregate, and share data over such constrained networks are needed. In this paper, we propose the use of constrained RESTful environments interfaces to build resource collections having a network lifetime increase in mind. More specifically, based on existing atomic resources, collections are created/designed to become available as new resources, which can be observed. Such resource design should not only match client's interests, but also increase network lifetime as much as possible. For this to happen, energy consumption should be balanced/fair among nodes so that node depletion is delayed. When compared with previous approaches, results show that energy efficiency and network lifetime can be increased while reducing control/registration messages, which are used to set up or change observations

Optimization of Mixed Numerology Profiles for 5G Wireless Communication Scenarios

The management of 5G resources is a demanding task, requiring proper planning of operating numerology indexes and spectrum allocation according to current traffic needs. In addition, any reconfigurations to adapt to the current traffic pattern should be minimized to reduce signaling overhead. In this article, the pre-planning of numerology profiles is proposed to address this problem, and a mathematical optimization model for their planning is developed. The idea is to explore requirements and impairments usually present in a given wireless communication scenario to build numerology profiles and then adopt one of the profiles according to the current users/traffic pattern. The model allows the optimization of mixed numerologies in future 5G systems under any wireless communication scenario, with specific service requirements and impairments, and under any traffic scenario. Results show that, depending on the granularity of the profiles, the proposed optimization model is able to provide satisfaction levels of 60–100%, whereas a non-optimized approach provides 40–65%, while minimizing the total number of numerology indexes in operation.Competitiveness and Internationalization Operational Programme (COMPETE 2020), the Regional Operational Program of the Algarve (2020), and Fundação para a Ciência e Tecnologia; i-Five: Extensão do acesso de espectro dinâmico para rádio 5G, POCI-01-0145-FEDER-030500. This work is also supported by Fundação para a ciência e Tecnologia within CEOT (Center for Electronic, Optoelectronic and Telecommunications) and the UID/MULTI/00631/2020 projectinfo:eu-repo/semantics/publishedVersio

Allocation of resources in SAaaS Clouds managing thing mashups

The sensing and actuation as-a-service is an emerging business model to make sensors, actuators and data from the Internet of Things more attainable to everyday consumer. With the increase in the number of accessible Things, mashups can be created to combine services/data from one or multiple Things with services/data from virtual Web resources. These may involve complex tasks, with high computation requirements, and for this reason cloud infrastructures are envisaged as the most appropriate solution for storage and processing. This means that cloud-based services should be prepared to manage Thing mashups. Mashup management within the cloud allows not only the optimization of resources but also the reduction of the delay associated with data travel between client applications and the cloud. In this article, an optimization model is developed for the optimal allocation of resources in clouds under the sensing and actuation as-a-service paradigm. A heuristic algorithm is also proposed to quickly solve the problem.FCT (Foundation for Science and Technology) from Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications) [UID/MULTI/00631/2020]info:eu-repo/semantics/publishedVersio