1 / 27

Wireless internet routing

Wireless internet routing. Philippe Jacquet. Internet and networking. Internet User plurality connected to Sources plurality. Wireless architectures. Three main architectures Point to point Base station Mesh. Signal processing complexity in ground wireless networks.

hamish-mcdaniel
Download Presentation

Wireless internet routing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wireless internet routing Philippe Jacquet

  2. Internet and networking • Internet • User plurality connected to • Sources plurality

  3. Wireless architectures • Three main architectures • Point to point • Base station • Mesh

  4. Signal processing complexity in ground wireless networks • Diagram Capacity-Range Hiperlan1&2 IEEE802.11a Capacity in bit/s Wavelan IEEE 802.11 UMTS pico-cell UMTS micro-cell bluetooth GSM UMTS distance in m

  5. Mobile ad hoc networks • Mesh and mobile

  6. 2. Wireless network capabilities required • DARPA’s proposal for LANdroids

  7. 2. Which wireless networks? Wireless community network MANET VANET wireless sensors

  8. Wireless networks Mobile ad hoc networks • Mobility makes link failure a necessity • Refresh period 1 second • Automatic self-healing • Local neighborhood is local space • Unlimited neighborhood size • Stadium network: N=10,000, with average degree 1,000 • BGP needs 1014 links exchange per refresh time • BGP fails on Wifi networks with 20 users at walking speed. • Heavy density kills link state management.

  9. Wireless internetMobile ad hoc routing • Mobile Ad hoc NETworks • Two protocol classes: • Proactive class • Reactive class

  10. Proactive class • Link state protocols • Full internet legacy • Topology compression • Periodic control traffic • Permanent routing tables • OLSR

  11. Reactive class • Distance vector based • Partial internet legacy • Path limited topology • On demand route discovery • Temporary routing tables • AODV

  12. Optimized Link State Routing protocol • Topology compression • Run light and fast, only on best routes • Carry a subset of the local table • Stay on selected links

  13. Topology compression graph(V,E) Optimized Link State Routing (OLSR) A mobile network can be very dense (ex: |V|=104,|E|=107) Instead advertizing all links, a node advertizes only its multipoint relays. The multipoint relay set much smaller than neighbor set

  14. Multipoint relay sets Multipoint relay set of a terminal : Neighbor subset that covers the two hop neighbors Goal: find the smallest posible multipoint relay set Multipoint relay links

  15. Multipoint relay set • Local computation • Need to know two-hop neighborhood • Optimal is NP hard • Greedy algorithm is optimal to factor • Good enough for performance

  16. Multipoint relay set • Greedy selection algorithm • On node A Intialize N2N2(A), Er(A). While (N2) do Find y in N(A) which maximizes |N2N(y)| Add Ay to Er(A) N2 N2- N(y) Return Er(A)

  17. Topology compression • In Erdös-Rényi random graph models: • In unit disk random graph model:

  18. Topology compression • The union of multipoint relay link sets is a remote-spanner • Nodes compute their routing tables with the remote-spanner and their local table. • Topology compression is lossless. • Optimal routes in tables also optimal in genuine topology. B A

  19. F H M Route optimality proof • By recursion: if D is at distance k from A in G(V,E) there exists a route of length k in G(V,E(A)+Er) from A to D • true for k=1: (A,D)E(A). • If true for k, then if D at distance k+1, let the chain F-H-D with d(A,F)=k-1 and d(A,H)=k. Node F is a two hop neighbor of node D. • Let M the multipoint relay of D which covers F. • M is at distance k from A, thus there exists a route L of length k in G(V,E(A)+Er) from A to M. • (M,D) Er, thus L+(M,D) is in G(V,E(A)+Er) and is of length k+1. A D

  20. Control traffic reduction • Topology reduction • Topology compression • Dissemination reduction • Information about topology move only on multipoint relay links • Further dissemination reduction • Wireless flooding • Total reduction

  21. Wireless flooding A single transmission per node broadcast emission Instead of a copy per link

  22. Dissemination reduction • link flooding (cost |E|) packet P node A P←reception(); If !(P==null) then if!(P  received) then insert P in received; B←last_emitter(P); for each C N(A) do if(C≠B) then send(P,C); • broadcast flooding (cost |V|) P←reception(); If !(P==null) then if!(P  received) then insert P in received; broadcast(P);

  23. Multipoint relay flooding • Only multipoint relays flood the information (reduction factor |Er|/|E|) P←reception(); If !(P==null) then if!(P  received) then insert P in received; B←last_emitter(P); if(BA  Er) then broadcast(P);

  24. Multipoint relay flooding • Packet P dissemination from node S. Any arbitrary A • Closest emitter of P to A: distance k • Prove that k≤1

  25. G’ Multipoint relay flooding F G H A

  26. OLSR neighbor sensing • Partial Link control on network layer • Periodic broadcast of hello message • Contain list of heared neighbors • Two way check

  27. MPR selection • Collect the 2-way neighbor lists of neighbor nodes • Run the selection algorithm. • Advertize MPR set in hello

More Related