Roofnet


Roofnet

Roofnet is an experimental 802.11b/g mesh network currently under development at the Computer Science and Artificial Intelligence Laboratory of the Massachusetts Institute of Technology (MIT). Part of the research project at MIT includes link-level measurements of 802.11, finding high-throughput routes in the face of lossy links, link adaptation, and developing new protocols which take advantage of radio’s unique properties (ExOR). The software developed for this project is available for free as open source.

Routing Protocol

The routing protocol is called SrcRR. There are two broadcasts used with the protocol. The first is periodic broadcasts used to determine a metric called ETX. These public broadcasts measure the probability that a packet between two nodes in radio contact reaches its destination. The second broadcast type is used to build up routing tables. A node 0 will broadcast that it wants to find a route to D. Then each node that receives the broadcast will add its id to the route and forward the packet on. When node D receives a packet, it will reply back along the route that was found for that packet. Then node 0 can use this information to determine the best route using the ETX metrics and the route information returned from its query.

Media Access and Forwarding

One media access and forwarding protocol tested with RoofNet was ExOR. ExOR simulates some advantages of multicasted data networks by using conventional 802.11 digital radios operated in broadcast modes.

The source radio uses routing data to establish a list of radios that could help reach the destination radio. The list is ordered so that radios closer to the destination are nearer to the head of the list. The destination is at the head of the list. The list is compactly stored in each packet.

Each packet also includes a list that shows the progress of each packet through the list of radios. This list has one entry per packet. Each entry is the number of radio that is closest to the destination and has retransmitted that packet. The source inistially sets this list all to the source radio's number.

Then, the source broadcasts a batch of packets.

Radios not on a packet's list discard the packet.

Radios on the list save the packet. They update their list of radios transmitting each packet. But they wait a calibrated time before they retransmit any packet. The time is less if they are closer to the destination. The time is a probabilistic estimate of the time to retransmit the packets that will be retransmitted by radios closer to the destination.

If a radio receives a packet transmitted from a radio that is closer to the destination, the farther radio throws away that packet, and never retransmits it. It also updates its list of packet progress.

As they work backwards toward the source, the retransmissions propagate the batch of packets' progress information back to the source radio.

At the end, a few packets of each batch sent by the source may never reach the destination. It sends these on by the most reliable route, using conventional routing.

ee also

* B.A.T.M.A.N.
* Meraki - Company commercializing roofnet by producing hardware and software.

External links

* [http://www.csail.mit.edu/index.php MIT Computer Science and Artificial Intelligence Laboratory ]

ources

* [http://pdos.csail.mit.edu/roofnet/doku.php MIT Roofnet project page]
* [http://pdos.csail.mit.edu/roofnet/doku.php?id=design MIT Roofnet Design page]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • ExOR (wireless network protocol) — Extremely Opportunistic Routing (ExOR) is a combination of routing protocol and media access control for a wireless ad hoc network, invented by Sanjit Biswas and Robert Morris of the MIT Artificial Intelligence Laboratory, and described in a 2005 …   Wikipedia

  • Mesh networking — For other meanings of the word mesh, see Mesh (disambiguation). Illustration of a mesh network Mesh networking (topology) is a type of networking where each node must not only capture and disseminate its own data, but also serve as a relay for… …   Wikipedia

  • History of wireless mesh networking — The core advantage of wireless mesh networks is their inherent ability to form a network on power up. Watch what happens in Fig 1, when the mesh nodes power up (green LED on box turns on). The nodes hear each other s broadcast and a network is… …   Wikipedia

  • Robert Tappan Morris — Infobox Criminal subject name = Robert Tappan Morris image size = 200px image caption = Robert Morris date of birth = birth date and age|1965|11|08 place of birth = date of death = place of death = alias = rtm conviction = Intentional access of… …   Wikipedia

  • Meraki — is a cloud networking company that provides hardware and software for building large scale wired and wireless networks. These networks are used by businesses, schools, and other organizations that need wireless access points, multi site wired… …   Wikipedia

  • Meraki — Meraki, de San Francisco en Californie, est un fabricant d équipements réseaux Wifi et de routeurs Ethernet qui a créé une solution globale dont la gestion se passe intégralement sur Internet. Cette entreprise fut fondée par deux étudiants… …   Wikipédia en Français

  • Wireless mesh network — Animation showing self healing wireless mesh (Click to enlarge) …   Wikipedia

  • Linksys WRT54G series — Linksys WRT54G (and variants WRT54GS, WRT54GL, and WRTSL54GS) is a Wi Fi capable residential gateway from Linksys. The device is capable of sharing Internet connections among several computers via 802.3 Ethernet and 802.11b/g wireless data… …   Wikipedia

  • Expected Transmission Count — The ETX metric, or Expected Transmission Count, is a measure of the quality of a path between two nodes in a wireless packet data network. It is used extensively in mesh networking algorithms.HistoryDouglas S.J. De Couto was the first to describe …   Wikipedia

  • Drahtloses Netzwerk — Wireless Local Area Network [ˈwaɪəlɪs ləʊkl ˈɛəɹɪə ˈnɛtwɜːk] (engl. „drahtloses lokales Netzwerk“ – Wireless LAN, W LAN, WLAN) bezeichnet ein „drahtloses“, lokales Funknetz, wobei meistens ein Standard der IEEE 802.11 Familie gemeint ist. Für… …   Deutsch Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.