DGT - Distributed Geographic Table


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In recent years tracking and localization devices have become of widespread use and are increasingly applied both to industrial and social services. Location information obtained through GPS-based outdoor localization systems is exploited in a growing number of search engines, navigation systems and social networks.
Existing solutions for maintaining user/device location information are usually based on one or more central servers that manage the information and allow for its retrieval, processing and distribution to active users. 

"DGT defines and implements a P2P overlay network where each node (software programs running on a mobile device) to be aware of nodes that are ”geographi- cally” (rather than ”virtually” on the network) close to them."


Flash Player by Enrico Lai distribuito con licenza Creative Commons (




Distributed Geographic Table (DGT) refers to a distributed system where a participating node can efficiently retrieve nodes or resources (data or services) placed near any global position. Responsibility for maintaining information about the posi- tion of active peers is distributed among nodes, in such a way that a change in the set of participants causes a minimal amount of disruption.

In the following image (Click on it to enlarge) you can see some photos of different steps associated to a DGT's peer. The Node (green marker) has a real path with a starting and an ending point (green markers with "1" and "2") and during the simulation moves on that path. You can see the changes during his movements in terms of neighbors organized according to the geographic distance from the analyzed peer.

The following image (Click on it to enlarge) shows a scenario where a peer (green marker) is moving from an area with an high density of peers to an area with a low density. Step by step it updates his neighbor list finding new close and available nodes and removing old references of peer with an high distance .  


M.Picone, M. Amoretti, F. Zanichelli. Evaluating the Robustness of the DGT Approach for Smartphone-based Vehicular Networks. 5th IEEE Workshop On User MObility and VEhicular Networks, Bonn Germany (Colocated with LCN 2011), October 4-7, 2011. (PaperPresentation)

M. Picone, M. Amoretti, F. Zanichelli. Proactive Neighbor Localization Based on Distributed Geographic Table.  To appear on the Emerald International Journal of Pervasive Computing and Communications. (Link)

M. Picone, M. Amoretti, F. Zanichelli. Proactive Neighbor Localization Based on Distributed Geographic Table. 8th International Conference on Advances in Mobile Computing & Multimedia (MoMM2010), 8 - 10 November 2010,Paris, France (Paper - Presentation)

M. Picone, M. Amoretti, F. Zanichelli. GeoKad: A P2P Distributed Localization Protocol. Work in Progress at 8th IEEE International Conference on Pervasive Computing and Communications PerCom 2010 Mannheim, Germany, March 29 - April 2, 2010 (Paper - Poster)


- Marco Picone (DSG Page)
- Michele Amoretti (
DSG Page)
- Francesco Zanichelli (
DSG Page)