Research

Research areas

Underwater acoustic networks

The quest towards ubiquitous wireless communications in every environment faces a grand challenge when moving under the surface of seas and oceans. In fact, the wireless radio communication technologies we are used to on land find little application under water. Over the last 10-15 years, wireless underwater communications have been developed using sound to communicate over long distances. Yet, sound-based communications are very resource-constrained, and at the same time quite slow with respect to terrestrial radio communications. Low transmission rates (on the order of a few kilobits per second), a propagation speed of only about 1500 m/s, and high energy consumption with respect to terrestrial radio, make it very important to correctly organize communications effectively. In this respect, we investigate smart scheduling, routing and error control algorithms to make underwater communications more proficient and reliable. The group has a broad expertise with experimental underwater networking and participated to many sea trials over the last 10 years. 

   

Multimodal underwater communications

Several different physical layer (PHY) technologies have been developed to communicate under water. While most of them rely on acoustic communications at different frequencies and over different bandwidths, optical communications and radio-frequency (RF) electro-magnetic communications are also gaining momentum. Each of the above underwater PHY technologies offers a different balance of advantages and disadvantages. The most prominent differences between underwater acoustic and optical communications, for instance, concern the data rate (order-of-kbit/s for acoustics, several Mbit/s for optics) and the range (up to several~km for acoustics up to a few meters for optics). Given the competing constraints of different underwater PHY technologies, there is a lot of potential in the integration of different PHYs into a multi-modal communication system. Recent work supports the vision of multi-modal systems by showing that embedded processing platforms have sufficiently evolved to host the signal processing algorithms of acoustic communication systems on general-purpose computing platforms.

In the context of multi-modal communication systems, the UWN group at IMDEA Networks works on several aspects of the logic that makes this kind of communications possible. This includes transmission scheduling, MAC protocols, routing and autonomous switching mechanisms based on the anticipatory sensing of acoustic and optical channel properties. Special care is exercised to make our approach and algorithms valid with any network topology, and applicable to any combination of available PHY technologies.
 

   

Single-anchor acoustic ranging and localization

Extensive ocean investigation is mandated by several applications, e.g., in the conservation, ecology, resource prospection and tactical domains. Many of these applications require geo-located data, which in turn relies on localization and range estimation algorithms. Therefore, a precise and robust range estimation process, which possibly does not consume an excessive amount of computational resources is essential. We tackle this problem by exploiting minimal environmental knowledge in order to determine the range between a node and an anchor deployed within a given area, without requiring any time synchronization. 
As obtaining full knowledge of the environment is often infeasible, we designed a method to improve the accuracy of ranging by taking into account at least the effect of refraction on sound propagation. The primary advantage of our method is that it leverages on the processing of multipath arrivals at the receiver, and therefore it does not require additional equipment.

   

Localization and tracking in mmWave networks

The characteristics of radio propagation at mmWave frequencies have interesting implications for the localization of radio terminals. Among the most significant ones, propagation is quasi-optical, with clear line-of-sight paths (when not obstructed), clearly identifiable reflections, and little if any scattering. These features require to rethink localization methods for indoor users employing mmWave communication technologies, in such a way that the results do not rely on exceedingly complex approaches. In this context, we design algorithms that work both with multiple and with a single anchor node, a promising approach in mmWave scenarios, where the predominant power comes from the LoS component, and the richness of indoor multipath propagation makes it possible to discriminate multipath components in the angular domain. Our results are backed by a number of experimental measurements carried out in collaboration with IMDEA Networks's Wireless Networking group.

 

Research Projects

MobArch

A Mobility-driven Architecture for Multi-modal Underwater Networking
 
Contact: Paolo Casari (paolo.casari@imdea.org)
Funded by: US Office of Naval Research
Duration: 2015-2016
[The UWN group at IMDEA Networks participates through a collaboration with the SIGNET group of the University of Padova, Italy]

RECAP

Reliable Capacity Provisioning and Enhanced Remediation for Distributed Cloud Applications

Contact: Paolo Casari (paolo.casari@imdea.org)
Website: [to be announced]
Funded by: European Union. ICT Programme H2020
Duration: January 2017 through December 2019