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- ndnIoT-FC: IoT devices as first-class traffic in name data networksPublication . Gameiro, Luís; Senna, Carlos; Luís, MiguelIn recent years we have been assisting a radical change in the way devices are connected to the Internet. In this new scope, the traditional TCP/IP host-centric network fails in large-scale mobile wireless distributed environments, such as IoT scenarios, due to node mobility, dynamic topologies and intermittent connectivity, and the Information-Centric Networking (ICN) paradigm has been considered the most promising candidate to overcome the drawbacks of host-centric architectures. Despite bringing efficient solutions for content distribution, the basic ICN operating principle, where content must always be associated with an interest, has serious restrictions in IoT environments in relation to scale, performance, and naming, among others. To address such drawbacks, we are presenting ndnIoT-FC, an NDN-based architecture that respects the ICN rules but offers special treatment for IoT traffic. It combines efficient hybrid naming with strategies to minimize the number of interests and uses caching strategies that virtually eliminates copies of IoT data from intermediate nodes. The ndnIoT-FC makes available new NDN-based application-to-application protocol to implement a signature model operation and tools to manage its life cycle, following a publisher-subscriber scheme. To demonstrate the versatility of the proposed architecture, we show the results of the efficient gathering of environmental information in a simulation environment considering different and distinct use cases.
- Hybrid wireless network with SDN and legacy devices in ad-hoc environmentsPublication . Sousa, Daniela; Sargento, Susana; Luís, MiguelOn temporary events, like concerts or emergency scenarios, where a communication infrastructure may not be sufficient or even present, networks can be built in a spontaneous way with the available network elements and radio access technologies, to support proper communication and data access. However, these ad-hoc networks, without a centralized view, can be inefficient when compared to a detached centralized control approach like in Software Defined Networks (SDNs). Moreover, SDNs can bring several advantages to these environments, such as adaptability and performance increase, despite not supporting wireless interfaces. However, in these scenarios, not all nodes are able to support SDN. This paper proposes a Spontaneous Heterogeneous Wireless Software Defined Network with a hybrid approach that is able to opportunistically use all available elements that may compose the network, regardless of whether they are legacy or SDN nodes. The proposed approach is tested in several scenarios with a different ratio of legacy to SDN nodes. We conclude that the network is able to work with hybrid nodes, and that when more Hybrid SDN (H-SDN) devices are used to forward packets, the network performance increases or is maintained when compared to a pure ad-hoc solution.
- Evaluation of content dissemination strategies in urban vehicular networksPublication . Pessoa, Gonçalo; Guardalben, Lucas; Luís, Miguel; Senna, Carlos; Sargento, SusanaThe main drivers for the continuous development of Vehicularad-hoc Networks (VANETs) are safety applications and services. However, in recent years, new interests have emerged regarding the introduction of new applications and services for non-urgent content (e.g., videos, ads, sensing and touristic information) dissemination. However, there is a lack of real studies considering content dissemination strategies to understand when and to whom the content should be disseminated using real vehicular traces gathered from real vehicular networks. This work presents a realistic study of strategies for dissemination of non-urgent contente with the main goal of improving contente delivery as well as minimizing network congestion and resource usage. First, we perform an exhaustive network characterization. Then, several content strategies are specified and evaluated in different scenarios (city center and parking lot). All the obtained results show that there are two content distribution strategies that clearly set themselves apart due to their superior performance: Local Rarest Bundle First and Local Rarest Generation First.
- Improving LoRa network simulator for a More realistic approach on LoRaWANPublication . Francisco, Sérgio; Pinho, Pedro; Luís, MiguelNowadays, the need for information is rapidly increasing, urging the development of technology to obtain reliable information. Under the scope of Smart Cities, Low Power Wide Area Networks (LPWANs) have been seen as one of the enabling technologies for the data gathering process but, the evaluation of new methods and solutions in large-scale, real world-scenarios, is a challenging and sometimes an impossible task. Thus, the need to use tools enabling the simulation of such networks arose, triggering the development of different network simulators. In this work we focus on the simulation of LoRa networks. Resorting on the LoRa network simulator mostly used in the literature, the LoRaSim, we study the impact of different propagation and the capture-effect models in the performance of a LoRa network. In addition, an extension to LoraSim is implemented, offering the capability to tweak the network on a more detailed fashion, by supporting distinguished parameters (spreading factor, bandwidth, code rate and payload) on the end-devices. Results show that when applying a well-known propagation model (Okumura-Hata) and a more realistic capture-effect on a network that emphasizes the use of orthogonality among all devices, this heterogeneity greatly increases its efficiency and quality.
- EmuCD: an emulator for content dissemination protocols in vehicular networksPublication . Chaves, Ricardo; Senna, Carlos; Luís, Miguel; Sargento, Susana; Moreira, André; Recharte, Diogo; Matos, RicardoThe development of protocols for mobile networks, especially for vehicular ad-hoc networks (VANETs), presents great challenges in terms of testing in real conditions. Using a production network for testing communication protocols may not be feasible, and the use of small networks does not meet the requirements for mobility and scale found in real networks. The alternative is to use simulators and emulators, but vehicular network simulators do not meet all the requirements for effective testing. Aspects closely linked to the behaviour of the network nodes (mobility, radio communication capabilities, etc.) are particularly important in mobile networks, where a delay tolerance capability is desired. This paper proposes a distributed emulator, EmuCD, where each network node is built in a container that consumes a data trace that defines the node's mobility and connectivity in a real network (but also allowing the use of data from simulated networks). The emulated nodes interact directly with the container's operating system, updating the network conditions at each step of the emulation. In this way, our emulator allows the development and testing of protocols, without any relation to the emulator, whose code is directly portable to any hardware without requiring changes or customizations. Using the facilities of our emulator, we tested InterPlanetary File System (IPFS), Sprinkler and BitTorrent content dissemination protocols with real mobility and connectivity data from a real vehicular network. The tests with a real VANET and with the emulator have shown that, under similar conditions, EmuCD performs closely to the real VANET, only lacking in the finer details that are extremely hard to emulate, such as varying loads in the hardware.
- LoRa connectivity analysis for urban coverage in real mobile environmentsPublication . Oliveira, Rui; Luís, Miguel; Sargento, SusanaFor the last few years, LoRa technology has been affirming itself as one of the most prominent and widely adopted low power wide area technologies. Very compatible with Internet of Things (IoT) applications and urban environments, this technology is capable of long range communications although with small bandwidths, and consequently, low data rates. Nevertheless, the quality of LoRa communications, like many other wireless technologies, are highly dependent on the transmission's context. In this work, we evaluate the performance of LoRa communications in a mobile sensing scenario, and study its capability to give wireless coverage to a small-size city. Experimental results show that velocity has a consistent and increasing impact on the packet delivery ratio, and that the coverage capability is much more dependent on the terrain distribution and Line-of-Sight (LoS), than on the distance between the mobile node and the gateway.
- Using aerial and vehicular NFV infrastructures to agilely create vertical servicesPublication . Nogales, Borja; Silva, Miguel; Vidal, Ivan; Luís, Miguel; VALERA, FRANCISCO; Sargento, Susana; Azcorra, Arturo5G communications have become an enabler for the creation of new and more complex networking scenarios, bringing together different vertical ecosystems. Such behavior has been fostered by the network function virtualization (NFV) concept, where the orchestration and virtualization capabilities allow the possibility of dynamically supplying network resources according to its needs. Nevertheless, the integration and performance of heterogeneous network environments, each one supported by a different provider, and with specific characteristics and requirements, in a single NFV framework is not straightforward. In this work we propose an NFV-based framework capable of supporting the flexible, cost-effective deployment of vertical services, through the integration of two distinguished mobile environments and their networks: small sized unmanned aerial vehicles (SUAVs), supporting a flying ad hoc network (FANET) and vehicles, promoting a vehicular ad hoc network (VANET). In this context, a use case involving the public safety vertical will be used as an illustrative example to showcase the potential of this framework. This work also includes the technical implementation details of the framework proposed, allowing to analyse and discuss the delays on the network services deployment process. The results show that the deployment times can be significantly reduced through a distributed VNF configuration function based on the publish-subscribe model.
- Edge virtualization in multihomed vehicular networksPublication . Silva, Miguel; Luís, Miguel; Sargento, SusanaVehicular Networks (VANETs) are a critical component of a Smart City environment. They extended the connectivity plane with support for a wide range of applications, from safety to entertainment. Such services, when deployed outside the vehicular network, may imply an additional delay, which can be critical. In addition, these services become inaccessible whenever the vehicles lose contact with the infrastructure.This paper proposes a practical solution that aims to minimize the impact of the services' location and its inaccessibility in a VANET. The solution focuses on using Network Function Virtualization technologies to support the deployment of the services at the edge of a mobility-enabled multihomed VANET, thus allowing the services to be accessible in intermittent connectivity situations, as well as enabling lower delays for critical services. The results obtained show that the solution is capable of deploying services at the edge of the VANET with low delay and with a fast recovery when in handover and mobility scenarios.
- A fair channel hopping scheme for LoRa Networks with multiple single-channel gatewaysPublication . Figueiredo, Alexandre; Luís, Miguel; ZÚQUETE, ANDRÉLoRa is one of the most prominent LPWAN technologies due to its suitable characteristics for supporting large-scale IoT networks, as it offers long-range communications at low power consumption. The latter is granted mainly because end-nodes transmit directly to the gateways and no energy is spent in multi-hop transmissions. LoRaWAN gateways can successfully receive simultaneous transmissions on multiple channels. However, such gateways can be costly when compared to simpler single-channel LoRa transceivers, and at the same time they are configured to operate with pure-ALOHA, the well-known and fragile channel access scheme used in LoRaWAN. This work presents a fair, control-based channel hopping-based medium access scheme for LoRa networks with multiple single-channel gateways. Compared with the pure-ALOHA used in LoRaWAN, the protocol proposed here achieves higher goodput and fairness levels because each device can choose its most appropriate channel to transmit at a higher rate and spending less energy. Several simulation results considering different network densities and different numbers of single-channel LoRa gateways show that our proposal is able to achieve a packet delivery ratio (PDR) of around 18% for a network size of 2000 end-nodes and one gateway, and a PDR of almost 50% when four LoRa gateways are considered, compared to 2% and 6%, respectively, achieved by the pure-ALOHA approach
- Context-based forwarding for mobile ICNsPublication . Gameiro, Luís; Senna, Carlos; Luís, MiguelOver the last couple of decades, mobile ad-hoc networks (MANETs) have been at the forefront of research, yet still are afflicted by high network fragmentation, due to their continuous node mobility and geographical dispersion. To address these concerns, a new paradigm was proposed, Information-Centric Networks (ICN), whose focus is the delivery of Content based on names. This article aims to use ICN concepts towards the delivery of both urgent and non-urgent information in urban mobile environments. In order to do so, a context-based forwarding strategy was proposed, with a very clear goal: to take advantage of both packet Names and Data, and node's neighbourhood analysis in order to successfully deliver content into the network in the shortest period of time, and without worsening network congestion. The design, implementation and validation of the proposed strategy was performed using the ndnSIM platform along with real mobility traces from communication infrastructure of the Porto city. The results show that the proposed context-based forwarding strategy presents a clear improvement regarding the Data resolution, while maintaining network overhead at a constant.