Channel-aware routing for underwater wireless networks

Abstract-This paper presents a new cross layer routing protocol for underwater wireless sensor networks. The solution, termed CARP for Channel-aware Routing Protocol, exploits link quality information for cross layer relay determination. Nodes are selected as relays if they have a (recent) history of successful transmissions to their neighbors. CARP combines link quality with simple topology information (hop count), thus being able to route around connectivity voids and shadow zones. The protocol is also designed to take advantage of power control for selecting robust links. The performance of CARP has been evaluated through ns2-based simulations, and compared to the performance of two previously proposed routing protocols, namely, FBR and DBR. Our results show that CARP robust relay selection mechanism enables it to achieve throughput efficiency that is up to twice the throughput of FBR and almost three times that of DBR. CARP also obtains remarkable performance improvements over FBR and DBR with respect to end-to-end packet latency and energy consumption. Index Terms-Underwater acoustic networks, cross layer design, MAC and routing protocols

Deployment of a persistent underwater acoustic sensor network: The CommsNet17 Experience

This paper presents the experimental activities performed by the NATO STO Centre for Maritime Research and Experimentation (CMRE) during the CommsNet17 trial where a persistent Underwater Acoustic Sensor Network (UASN) was deployed. The CommsNet17 trial was held from the 27th of November to the 6th of December in the Gulf of La Spezia (IT), close to the CMRE premises, using the CMRE Littoral Ocean Observatory Network (LOON) as one of its key components. A network consisting of up to eleven nodes was deployed, including static and mobile assets. Various aspects related to persistent UASNs were addressed, including autonomous and distributed network discovery and node configuration, node localisation and navigation, self-adjustment of the network topology in support to the assigned tasks, underwater docking, wireless battery recharging and data offloading. The collected results show that the employed solutions were able to successfully complete all these tasks, thus demonstrating the effective deployment of a persistent, distributed and ad-hoc UASN

A Hybrid Routing Protocol for Underwater Acoustic Networks

Session E: NetworksInternational audience—This paper presents a new packet-forwarding mechanism for underwater acoustic networks. The solution, termed MPR-Light, combines the modus operandi of the Multi-Point Relay (MPR) protocol and of the Enhanced Flooding (EFlood), both described in [1]. MPR-Light aims at providing the ro-bustness of a flooding solution in the presence of unreliable and asymmetric acoustic links, while reducing the network load and energy consumption at each node. No periodic control messages are transmitted by each data source or relay nodes. Any additional control data used to find the best relay towards the final destination is appended to regular data packets. Similarly to MPR, relay nodes are selected according to (recent) historical information considering different metrics, i.e. link quality, link liveliness and symmetry. When no information is available at a node, the EFlood approach is used. The performance of MPR-Light has been compared with that of MPR and EFlood during the CommsNet13 sea trial, organised by the NATO Centre for Maritime Research and Experimentation (CMRE) and conducted off the coast of the Palmaria island (La Spezia, Italy) in September 2013. A heterogeneous network of 12 nodes was deployed. Our results show that MPR-Light, using an hybrid strategy, is able to significantly reduce the overhead and energy consumption in the network while maintaining similar or better performance in terms of packet delivery ratio and end-to-end latency with respect to MPR and EFlood

Comparing the SUNSET and DESERT frameworks for in field experiments in underwater acoustic networks

The emerging demand for pervasive underwater monitoring and control systems has significantly stimulated the research on network protocols for underwater acoustic sensor networks. In the last few years, several solutions have been proposed for this kind of networks at all layers of the protocol stack. However, to achieve a thorough understanding of the performance of these protocols running simulations is no longer enough and in field experiments are needed. Two different platforms, SUNSET and DESERT, have been recently developed and released open-source allowing to seamlessly simulate, emulate and test (at-sea) a variety of communication protocols. In this paper we compare the performance of these two frameworks, with a particular attention to their use during in field experimentation. Our tests show that when running simulations there is high compatibility and interoperability between the two systems. In actual underwater experiments, however, SUNSET represents a more mature, flexible and efficient solution. © 2013 IEEE

A back-seat driver for remote control of experiments in underwater acoustic sensor networks

This paper presents a novel system to remotely control and reconfigure an heterogeneous underwater acoustic sensor network in scenarios with no direct access to all the underwater nodes after their deployment. The system uses the SUNSET framework to interact with and to operate the underwater network via single-hop and multi-hop acoustic transmissions. Users can remotely configure the underwater devices and the tests to run without the need to retrieve or bring to the surface the deployed nodes. The system allows the user to select different protocol stacks, protocol parameters and device behavior policies and to investigate the performance of several network configurations in an easy and fast way, avoiding that most of the experiment time is used to prepare the tests rather than to actually run the tests and collect the results. The presented mechanism has been successfully tested and validated during three in field campaigns, considering different underwater environments and communication devices. Our results show that the time to remotely control and reconfigure several batteries of tests for a variety of network configurations reduces to few tens of seconds, thus enhancing robustness and flexibility and significantly reducing the costs and logistic complexity of in field experiments. © 2013 IEEE

Efficiently reconfigurable backbones for wireless sensor networks

We present the definition and performance evaluation of a protocol for building and maintaining a connected backbone among the nodes of a wireless sensor networks (WSN). Building backbones first, and then coping with network dynamics is typical of protocols for backbone formation. Rules for building the backbone, however, do not take into account the following network dynamics explicitly. This makes maintaining a connected backbone quite costly, especially in terms of reorganization time, overhead and energy consumption. Our protocol includes in the backbone forming operations a fail-safe mechanism for dealing with the addition and the removal of nodes, which are typical events in a WSN. More specifically, the network is kept partitioned into clusters that are cliques, i.e., nodes in each cluster are directly connected to each others. Therefore, removing a node does not disrupt a cluster, and adding one requires simple operations for checking node admission to the cluster. The protocol, termed CC ("double C", for clique clustering), comprises three phases, each designed to render the operations of the others swift and efficient. The first phase partitions the network into clusters that are cliques. Clusters are then joined to form a backbone that is provably connected. Finally, the third, more on-line phase, maintains the backbone connected in face of node additions and removals. We compare the performance of CC with that of DMAC, a protocol that has been previously proposed for building and maintaining clusters and backbones in presence of network dynamics. Our comparison concerns metrics that are central to WSN research, such as time for clustering and backbone reorganization, corresponding overhead, extent of the reorganization (i.e., number of nodes involved in it), and properties of the resulting backbone, such as its size, backbone route length, number of gateways and nodes per cluster. Our ns2-based simulation results show that the design criteria chosen for CC are effective in producing backbones that can be reconfigured quickly and with remarkably lower overhead. (c) 2007 Elsevier B.V. All rights reserved

Fail-safe hierarchical organization for wireless sensor networks

This paper presents the definition and evaluation of a new protocol for providing a wireless sensor network (WSN) with a hierarchical organization. Differently from previously proposed solutions, our protocol, termed CC ("double c," for clique clustering), includes in its operation a fail-safe mechanism for dealing with node failure or removal, which are typical of WSNs. More specifically, the network is partitioned into clusters that are cliques, i.e., nodes in each clusters are directly connected to each others. An efficient mechanism for building a connected backbone among the clique clusters is provided. Clustering, backbone formation and backbone maintenance are completely localized, in the precise sense that only nodes physically close to a failing node are involved in the reconfiguration process. We compare the performance of CC with that of DMAC, a protocol that has been previously proposed for building and maintaining clusters and backbones in presence of node removal. Our comparison concerns metrics that are central to WSN research, such as time for clustering and backbone reorganization, corresponding overhead (in bytes and transmission energy), backbone size, extent of the reorganization (i.e., the number of nodes involved in it), and backbone route length. Our ns2-based simulation results show that the design criteria chosen for CC are effective in producing backbones that can be reconfigured quickly (63% faster than DMAC's) and with remarkably lower overhead. © 2007 IEEE