Manlio Bacco

UAVs in WSNs for agricultural applications: An analysis of the two-ray radio propagation model

In this work, we discuss the radio propagation model of the UAVs when they act as mobile nodes belonging to a ground wireless sensor network. A typical application scenario is the agricultural field, where ground sensor nodes communicate with a flying node (the UAV). Currently, UAVs are attracting much attention both in the market and in the research field, thus more accurate radio propagation models are needed to properly estimate the effectiveness and the feasibility of the use of UAVs in several contexts. The main contribution of this work is in highlighting that the classical two-ray path loss model may be not enough accurate to take into account all the different factors that must be considered when using an UAV to communicate with and to control a ground Wireless Sensor Network.

A study on TCP error recovery interaction with Random Access satellite schemes

Random Access (RA) techniques have been included in the novel DVB-RCS2 standard due to an expected efficiency in addressing SCADA and M2M traffic. Such traffic relies on intermittent sources sending short messages on a periodic time scale. Efficiency is usually assessed in terms of layer-2 packet loss rate without taking into account indirect effects on upper layer protocols. In particular, TCP assumes packet losses as a congestion indication triggering actions aimed to reduce actual transmission rate. As a consequence, TCP over RA can be impaired by some cross-effects, which deteriorate the performance as experienced by the applications, in terms of Round Trip Time (RTT) and overall throughput. The scope of this paper is to analyze such dynamics, by applying a top-down approach, which includes TCP parameters tuning in the scenario configuration. To this aim, an NS2 module has been developed to simulate different flavors of random access techniques for GEO satellite channels integrated with sensor data sources, which produce intermittent messages and send them over TCP connections. Achieved results provide a first set of considerations on the best protocol stack configuration according to TCP traffic load.

Environmental Monitoring for Smart Cities

This paper presents an innovative, multidisciplinary, and cost-effective ecosystem of ICT solutions able to collect, process, and distribute geo-referenced information about the influence of pollution and micro-climatic conditions on the quality of life in Smart Cities. The system has been developed and experimentally evaluated in the framework of the research project Smart Healthy Environment, co-funded by the Tuscany Region (Italy). Specifically, an innovative monitoring network has been developed, constituted by fixed and mobile sensor nodes, which provided comparable measurements in stationary and mobile conditions. In addition, sensor data have been enriched with those generated by citizens through the use of a dedicated mobile application, exploiting participatory sensing and mobile social network paradigms.

Satellites, UAVs, Vehicles and Sensors for an Integrated Delay Tolerant Ad Hoc Network

In this paper, a fully meshed mobile ad hoc network is introduced as an alternative to a classical wide area network, as the Internet. Internet of Things, Internet of Vehicles, Unmanned Aerial Vehicles and satellites are the enabling technologies of such a complex scenario with support to multilevel mobility, overlaid deployments, as well as techniques offering Delay Tolerant Networks services.

Advances on elastic traffic via M2M satellite user terminals

Owing to the variety of traffic profiles that Machine to Machine and Internet of Things applications may generate, this work studies the applicability of the Contention Resolution Diversity Slotted ALOHA (CRDSA) random access scheme, as in the DVB-RCS2 standard, when clusters of sensor nodes exchange data via satellite toward a sink via short-lived TCP/IP connections. In this scenario, uncorrelated sensor sources generate measurements, which are multiplexed by a satellite terminal, before being encapsulated and delivered through TCP/IP flows. This work aims at investigating the scalability in terms of number of concurrent satellite terminals, which can successfully transfer their own data with a small delivery delay in order to avoid congestion phenomena at MAC layers, which may induce collision storms. This work assesses the best practice for M2M elastic traffic wia random access satellite, investigating on cross-layer interactions between access layer and transport/application layers.

Network Coding Applications to High Bit-Rate Satellite Networks

Satellite networks are expected to support multimedia traffic flows, offering high capacity with QoS guarantees. However, system efficiency is often impaired by packet losses due to erasure channel effects. Reconfigurable and adaptive air interfaces are possible solutions to alleviate some of these issues. On the other hand, network coding is a promising technique to improve satellite network performance. This position paper reports on potential applications of network coding to satellite networks. Surveys and preliminary numerical results are provided on network coding applications to different exemplary satellite scenarios. Specifically, the adoption of Random Linear Network Coding (RLNC) is considered in three cases, namely, multicast transmissions, handover for multihomed aircraft mobile terminals, and multipath TCP-based applications. OSI layers on which the implementation of networking coding would potentially yield benefits are also recommended.

Generalized Encoding CRDSA: Maximizing Throughput in Enhanced Random Access Schemes for Satellite

This work starts from the analysis of the literature about the Random Access protocols with contention resolution as Contention Resolution Diversity Slotted Aloha (CRDSA) and introduces a possible enhancement, named Generalized Contention Resolution Diversity Slotted Aloha (GE-CRDSA). The GE-CRDSA aims to improve the aggregated throughput when the system load is less than 50%, playing on the opportunity of transmitting an optimal combination of information and parity packets frame by frame.

TCP New Reno over DVB-RCS2 Random Access Links: Performance Analysis and Throughput Estimation

Application of random access schemes in the return link of satellite systems shows appealing advantages over demand assignment multiple access (DAMA) especially in case of bursty traffic (e.g., M2M). The interactions of TCP with random access has been however only marginally explored by the scientific community, thus limiting the appeal of random access. This paper attempts to bridge this gap, by providing insights into the performance of TCP-based services running on top of DVB-S2/RCS2 satellite networks implementing Contention Resolution Diversity Slotted Aloha (CRDSA) as random access scheme. A special attention has been also dedicated to TCP modeling, since classical TCP throughput formulations fail in the proposed scenario, whereby a simple but effective enhancement is proposed in this paper.

Application protocols enabling internet of remote things via random access satellite channels

Nowadays, Machine-to-Machine (M2M) and Internet of Things (IoT) traffic rate is increasing at a fast pace. The use of satellites is expected to play a large role in delivering such a traffic. In this work, we investigate the use of two of the most common M2M/IoT protocols stacks on a satellite Random Access (RA) channel, based on DVB-RCS2 standard. The metric under consideration is the completion time, in order to identify the protocol stack that can provide the best performance level.

A Survey on Network Architectures and Applications for Nanosat and UAV Swarms

Nanosatellites and unmanned aerial vehicles are attracting more and more the interest of both industrial and research fields. They are low-cost and easy deployable items, therefore their use is expected to quickly grow in the next few years. This work proposes a survey on the network architectures and the applications for nanosatellite swarms and constellations, as well as for flying ad hoc networks, by characterizing distinctive features and issues yet to be resolved in order to take advantage from both technologies in a joint fashion.