3,284 research outputs found
Fundamental Limits of Wideband Localization - Part II: Cooperative Networks
The availability of positional information is of great importance in many
commercial, governmental, and military applications. Localization is commonly
accomplished through the use of radio communication between mobile devices
(agents) and fixed infrastructure (anchors). However, precise determination of
agent positions is a challenging task, especially in harsh environments due to
radio blockage or limited anchor deployment. In these situations, cooperation
among agents can significantly improve localization accuracy and reduce
localization outage probabilities. A general framework of analyzing the
fundamental limits of wideband localization has been developed in Part I of the
paper. Here, we build on this framework and establish the fundamental limits of
wideband cooperative location-aware networks. Our analysis is based on the
waveforms received at the nodes, in conjunction with Fisher information
inequality. We provide a geometrical interpretation of equivalent Fisher
information for cooperative networks. This approach allows us to succinctly
derive fundamental performance limits and their scaling behaviors, and to treat
anchors and agents in a unified way from the perspective of localization
accuracy. Our results yield important insights into how and when cooperation is
beneficial.Comment: To appear in IEEE Transactions on Information Theor
Hybrid-Vehfog: A Robust Approach for Reliable Dissemination of Critical Messages in Connected Vehicles
Vehicular Ad-hoc Networks (VANET) enable efficient communication between
vehicles with the aim of improving road safety. However, the growing number of
vehicles in dense regions and obstacle shadowing regions like Manhattan and
other downtown areas leads to frequent disconnection problems resulting in
disrupted radio wave propagation between vehicles. To address this issue and to
transmit critical messages between vehicles and drones deployed from service
vehicles to overcome road incidents and obstacles, we proposed a hybrid
technique based on fog computing called Hybrid-Vehfog to disseminate messages
in obstacle shadowing regions, and multi-hop technique to disseminate messages
in non-obstacle shadowing regions. Our proposed algorithm dynamically adapts to
changes in an environment and benefits in efficiency with robust drone
deployment capability as needed. Performance of Hybrid-Vehfog is carried out in
Network Simulator (NS-2) and Simulation of Urban Mobility (SUMO) simulators.
The results showed that Hybrid-Vehfog outperformed Cloud-assisted Message
Downlink Dissemination Scheme (CMDS), Cross-Layer Broadcast Protocol (CLBP),
PEer-to-Peer protocol for Allocated REsource (PrEPARE), Fog-Named Data
Networking (NDN) with mobility, and flooding schemes at all vehicle densities
and simulation times
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