Electronically-switched Directional Antennas for Low-power Wireless Networks: A Prototype-driven Evaluation

We study the benefits of electronically-switched directional antennas in low-power wireless networks. This antenna technology may improve energy efficiency by increasing the communication range and by alleviating contention in directions other than the destination, but in principle requires a dedicated network stack. Unlike most existing works, we start by characterizing a real-world antenna prototype, and apply this to an existing low-power wireless stack, which we adapt with minimal changes. Our results show that: i) the combination of a low-cost directional antenna and a conventional network stack already brings significant performance improvements, e.g., nearly halving the radio-on time per delivered packet; ii) the margin of improvement available to alternative clean-slate protocol designs is similarly large and concentrated in the control rather than the data plane; iii) by artificially modifying our antenna's link-layer model, we can point at further potential benefits opened by different antenna designs

Demo Abstract: From Business Process Specifications to Sensor Network Deployments

makeSenseCONE

Towards Business Processes Orchestrating the Physical Enterprise with Wireless Sensor Networks

The industrial adoption of wireless sensor net- works (WSNs) is hampered by two main factors. First, there is a lack of integration of WSNs with business process modeling languages and back-ends. Second, programming WSNs is still challenging as it is mainly performed at the operating system level. To this end, we provide makeSense: a unified programming framework and a compilation chain that, from high-level business process specifications, generates code ready for deployment on WSN nodes

Efficacy of a new technique - INtubate-RECruit-SURfactant-Extubate - "IN-REC-SUR-E" - in preterm neonates with respiratory distress syndrome: Study protocol for a randomized controlled trial

Background: Although beneficial in clinical practice, the INtubate-SURfactant-Extubate (IN-SUR-E) method is not successful in all preterm neonates with respiratory distress syndrome, with a reported failure rate ranging from 19 to 69 %. One of the possible mechanisms responsible for the unsuccessful IN-SUR-E method, requiring subsequent re-intubation and mechanical ventilation, is the inability of the preterm lung to achieve and maintain an "optimal" functional residual capacity. The importance of lung recruitment before surfactant administration has been demonstrated in animal studies showing that recruitment leads to a more homogeneous surfactant distribution within the lungs. Therefore, the aim of this study is to compare the application of a recruitment maneuver using the high-frequency oscillatory ventilation (HFOV) modality just before the surfactant administration followed by rapid extubation (INtubate-RECruit-SURfactant-Extubate: IN-REC-SUR-E) with IN-SUR-E alone in spontaneously breathing preterm infants requiring nasal continuous positive airway pressure (nCPAP) as initial respiratory support and reaching pre-defined CPAP failure criteria. Methods/design: In this study, 206 spontaneously breathing infants born at 24+0-27+6 weeks' gestation and failing nCPAP during the first 24 h of life, will be randomized to receive an HFOV recruitment maneuver (IN-REC-SUR-E) or no recruitment maneuver (IN-SUR-E) just prior to surfactant administration followed by prompt extubation. The primary outcome is the need for mechanical ventilation within the first 3 days of life. Infants in both groups will be considered to have reached the primary outcome when they are not extubated within 30 min after surfactant administration or when they meet the nCPAP failure criteria after extubation. Discussion: From all available data no definitive evidence exists about a positive effect of recruitment before surfactant instillation, but a rationale exists for testing the following hypothesis: a lung recruitment maneuver performed with a step-by-step Continuous Distending Pressure increase during High-Frequency Oscillatory Ventilation (and not with a sustained inflation) could have a positive effects in terms of improved surfactant distribution and consequent its major efficacy in preterm newborns with respiratory distress syndrome. This represents our challenge. Trial registration: ClinicalTrials.gov identifier: NCT02482766. Registered on 1 June 2015

Client announcement and Fast roaming in a Layer-2 mesh network

Research in Wireless Mesh Networking has been really active in the last years, with the birth of various ideas and the protocols that implement them. Nevertheless all the currently most deployed protocols have a lot of room for improvement and there are still open challenges that are meant to bring the performance to higher levels. Wireless Mesh Networks are involved in several studies also because of their applications which can be particularly useful in all those situations where wired infrastructures are not feasible. Common implementations rely on Layer-3 addressing and routing, but doing Mesh networking on Layer-2 address space is probably the best way for building a protocol needed to handle this kind of networks, since this task is not strictly related to the network (IP) layer. In particular, efficient client managing is not possible in case of a mesh routing protocol implemented on Layer-3 and this is probably one of the most important tasks of the routing protocol (after establishing routes, of course). This technical report focuses on the client announcement and the roaming problems that a protocol, embedded between Layer-2 and Layer-3, has to face. In particular, it focuses on B.A.T.M.A.N.-Advanced and defines new mechanisms that are meant to improve the protocol performance in client management and roaming. The current client announcement mechanism suffers from several problems, in particular from a high protocol overhead. The new strategy described in this technical report is meant to reduce such overhead and to increase the robustness of the whole announcement strategy. Up to now B.A.T.M.A.N.-Advanced hasn't ever provided a real mechanism to handle the roaming procedure, so this is the first one accounting this issue in the protocol. Performance are increased dramatically thus making it possible to measure real benefits in the user communications. This is probably the most prominent result obtained in this work which actually brings new possibilities for further improvements and for designing new mechanisms. The B.A.T.M.A.N.-Advanced protocol is actually transparent to the network layer by design, so the base idea behind the new roaming mechanism is to keep such transparency providing an on-time re-routing of the batman encapsulated data packets to the new destination. In this way it is possible to avoid affecting upper layers keeping them unaware of roaming, thus keeping all the connections active. The new mechanisms have been tested in the worst case roaming scenario for B.A.T.M.A.N.-Advanced. Such scenario consists in a topology made up by a chain of nodes of length $N$ (the longer the chain, worse the performance) on top of which a client served by the first node and one served by the last one are communicating. In case of any client movement (e.g. roaming to an adjacent node) the time needed by the new routing information to be spread among the network, and consequently make the connection work again, is proportional to the number of links that separate the two involved nodes. The experimental results, that are reported at the end of the technical report, show that even in this particular scenario the performance improvement given by the new mechanism is significant. The tests have been performed in an emulated environment where virtual machines, which acted as nodes, were created using QEMU-KVM. Therefore it has been possible to use the real B.A.T.M.A.N.-Advanced code instead of a possible error-prone implementation for any of the known network simulators (NS-2, NS-3, OMNET++, etc.)

Improving Mesh-Agnostic Client Announcement in B.A.T.M.A.N.-Advanced

Research in Wireless Mesh Networking has been very active in the past years, with the birth of several new ideas and the protocols that implement them. Most common implemen- tations rely on Layer-3 addressing and routing; however 802.11s and other successful protocols suggest that Mesh Networking on Layer-2 address space is more efficient, does not mingle with the global IP routing, and provides easier ways to support micro- mobility as well as client management. This paper focuses on the client announcement protocol, i.e., the functionality, somewhat embedded between Layer-2 and Layer-3, that allows routers in a mesh network to announce the clients they are serving and that in practice makes the entire routing protocol work correctly. In particular, it focuses on B.A.T.M.A.N.-Advanced, analyses the shortcomings of the simple implementation of this functionality present until v.2011.2.0 and defines the new protocol and algorithms that we have implemented and are part of the distribution starting from v.2011.3.0. Experiments in controlled scenarios show how performance increases dramatically even in scenarios designed specifically to stress the new protocol. The new mechanism and improved performance make it possible to design new features for B.A.T.M.A.N.-Advanced, most notably the support for fast and seamless handover, which is currently under testin

AOI cast by Tolerance Based Compass Routing in Distributed Virtual Environments

This paper presents an Area of Interest(AOI)-cast strategy for P2P Distributed Virtual Environment (DVE) which exploits a Delaunay Triangulation of the DVE to define a compass-based routing algorithm. A set of formal results for circular AOI is presented. Inconsistencies between local views of different peers due to the network latency are faced by introducing a tolerance threashold in the compass routing

Electronically-switched Directional Antennas for Low-power Wireless Networks: A Prototype-driven Evaluation

We study the benefits of electronically-switched directional antennas in low-power wireless networks. This antenna technology may improve energy efficiency by increasing the communication range and by alleviating contention in directions other than the destination, but in principle requires a dedicated network stack. Unlike most existing works, we start by characterizing a real-world antenna prototype, and apply this to an existing low-power wireless stack, which we adapt with minimal changes. Our results show that: i) the combination of a low-cost directional antenna and a conventional network stack already brings significant performance improvements, e.g., nearly halving the radio-on time per delivered packet; ii) the margin of improvement available to alternative clean-slate protocol designs is similarly large and concentrated in the control rather than the data plane; iii) by artificially modifying our antenna's link-layer model, we can point at further potential benefits opened by different antenna designs