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Mobile Ad-Hoc Networking

Mobile Ad-Hoc Networking. By Jared Roberts. Overview. What is a MANET? Problems with routing in a MANET Oh Node! (laugh!) Current Solutions. What is a MANET?.

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Mobile Ad-Hoc Networking

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  1. Mobile Ad-Hoc Networking By Jared Roberts

  2. Overview • What is a MANET? • Problems with routing in a MANET • Oh Node! (laugh!) • Current Solutions

  3. What is a MANET? • MANET – (Mobile Ad-Hoc NETwork) a system of mobile nodes (laptops, sensors, etc.) interfacing without the assistance of centralized infrastructure (access points, bridges, etc.)

  4. The Problem • Unstable paths • Processing power • Battery life • Time delays • High cost of memory

  5. Factors Affecting MANETs • Scalability • Power vs. Latency • Incompatible Standards • Data Rates • User Education • Security • Coverage

  6. Solutions • Table Driven • DSDV • CGSR • WRP • Source-initiated On-Demand Driven • AODV • DSR • LMR • TORA • ABR • SSR

  7. The Family Tree

  8. Destination-Sequenced Distance-Vector Routing (DSDV) • Every node maintains a routing table. • “Full” vs. “incremental” update • Settling time – the weighted average time that routes to a destination will fluctuate before the route with the best metric is received.

  9. Clusterhead Gateway Switch Routing (CGSR) • A central “clusterhead” node is chosen. • The clusterhead is chosen by the “Least Cluster Change” algorithm • Traffic is routed to the current clusterhead who forwards the traffic through a gateway node to the next clusterhead in line until the clusterhead of the destination node is located. • Each node must maintain a cluster member table

  10. CGSR (cont.)

  11. Wireless Routing Protocol (WRP) • 4 tables: Distance, routing, link-cost, and message retransmission list • Neighboring nodes broadcast update messages • Uses hello messages to establish connectivity • Checks all incoming update information

  12. Comparing Table Driven Routing Protocols

  13. Ad-hoc On-demand Distance Vector Routing (AODV) • Route Request Packets (RREQ) • The source node broadcasts an RREQ to all neighboring nodes. • Nodes record the source of the first RREQ received to establish a reverse path.

  14. AODV (cont.) • Route Reply Packets (RREP) • The destination or node with a route to the destination unicasts a RREP back to the source to establish a route.

  15. Dynamic Source Routing (DSR) • Each node maintains a route cache. • If a source node has no route in its cache, it broadcasts a route request. • A route reply is generated when either the destination or a node with a route to the destination is found. • Supports symmetric links

  16. DSR (cont.) • Maintenance is accomplished by route error packets and acknowledgements. • If a node fails to send an acknowledgement, any route that contains that node is truncated.

  17. Temporally-Ordered Routing Algorithm (TORA) • Used in highly dynamic networks • Provides multiple routes for source/destination pair • Uses direct acyclic graphs to measure “height” • Assumes all nodes have synchronized clocks • Classifies links as upstream and downstream

  18. TORA (cont.)

  19. Associativity-Based Routing (ABR) • Uses degree of association stability as a metric • Strives to build “longer-lived” routes

  20. Signal Stability Routing (SSR) • Selects routes based on signal strength and location stability • Periodic beacons update signal strength tables • Only requests that are received over strong channels are forwarded unless the PREF field in the header is set to allow weak channels

  21. Comparing Source-Initiated On-Demand Routing Protocols

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