An Adaptive Hybrid Routing Framework


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An Adaptive Hybrid Routing Framework

  1. 1. Independent Zone Routing: An Adaptive Hybrid Routing Framework for Mobile Ad Hoc Networks
  2. 2. Zone Routing Framework <ul><li>All nodes within “ zone radius” number of hops from a node belong to its “ routing zone.” </li></ul><ul><li>Nodes proactively maintain routes to all nodes within its routing zone using the Intra-zone Routing Protocol (IARP). </li></ul>Peripheral node Zone radius = 2 (hops) Neighbor node
  3. 3. Zone Routing Framework <ul><li>IZRP (The Inter zone Routing Protocol) finds routes to destinations beyond a node’s routing zone with the aid of BRP. </li></ul><ul><li>BRP (Bordercast Resolution Protocol) multicasts route query packets towards the peripheral nodes using topology info. provided by IARP. </li></ul><ul><li>Bordercast recipients bordercast the query toward their own peripheral nodes until a route to the destination is found. </li></ul>
  4. 4. Query Control in Zone Routing <ul><li>A node is covered by a query if it belongs to the routing zone of a node which has already received the query. </li></ul><ul><li>Query control: if downstream peripheral node along a branch has already been covered – then nodes do not forward queries along that. </li></ul>Desired Search Direction Desired Search Direction Desired Search Direction Desired Search Direction
  5. 5. Routing Zone Benefits <ul><li>Efficient multi-hop distribution </li></ul><ul><ul><li>Efficient bordercasting </li></ul></ul><ul><ul><li>Efficient global broadcasting (multi-point relaying) </li></ul></ul><ul><li>Proactive route maintenance </li></ul><ul><ul><li>Proactive route repair </li></ul></ul><ul><ul><li>Proactive route shortening </li></ul></ul><ul><ul><li>Source route compression </li></ul></ul><ul><li>Layer 2 support </li></ul><ul><ul><li>Unidirectional link discovery and usage </li></ul></ul><ul><ul><li>reliable neighbor broadcast </li></ul></ul><ul><li>Early route reply generation </li></ul><ul><li>Elective network participation - predictive partition checking for saving power </li></ul>
  6. 6. Optimal Zone Radius <ul><li>As zone radius is increased </li></ul><ul><ul><li>Proactive (IARP) traffic increases </li></ul></ul><ul><ul><li>Reactive (IERP) traffic decreases </li></ul></ul><ul><li>The benefits provided by the available topology information weighed against the overhead determines the optimal zone radius. </li></ul>Zone Radius Routing Overhead (or delay) Optimal zone radius Total IERP IARP
  7. 7. Motivation for Independent Zones <ul><li>Different parts of a network may have different characteristics, implying different optimal zone radii. </li></ul><ul><ul><li>High mobility and/or low call rates favor smaller zone radius. </li></ul></ul><ul><ul><li>Low mobility and/or high call rates favor larger zone radius. </li></ul></ul><ul><li>To allow each node to independently configure its optimal zone radius in a distributed fashion. </li></ul><ul><li>To allow the routing framework to quickly adapt to the changing conditions of the network. </li></ul><ul><li>Nodes be free to join and leave the network at any time, without any external configuration. </li></ul>
  8. 8. Independent Zone Routing (IZR) <ul><li>What if size of routing zones be different for different nodes? => Independent Zone Routing (IZR) framework. </li></ul><ul><li>Routing zone or receive zone: The neighborhood within zone radius number of hops about which a node proactively maintains routing information. </li></ul><ul><li>Send zone: All nodes which require proactive updates from a node lie in its send zone. </li></ul>
  9. 9. Receive Zones vs. Send Zones <ul><li>Independent zone radii imply regular receive-zones and not-so-regular send-zones . </li></ul>Receive zone S A C D E B Send zone A E S B D C
  10. 10. Intra-zone Routing Protocol (IARP) <ul><li>Suppose each node broadcasts “zone building packets” to the members of its routing zone </li></ul><ul><ul><li>Thus each node knows the extent of its send zone. </li></ul></ul><ul><li>Each node sets the initial value of the time-to-live (TTL 0 ) field of the update packet equal to the distance to the farthest member of its send zone. </li></ul>
  11. 11. IARP in IZR (Contd.) <ul><li>Peripheral nodes maintain expecting_nodes_list which help in dropping unnecessary update packets. </li></ul><ul><ul><li>A peripheral node drops the update packets if no node beyond it is expecting that update. </li></ul></ul>G J H A C B E D F K Receive Zone Send Zone TTL 0
  12. 12. Bordercast Resolution Protocol (BRP) <ul><li>Rebordercast node: node closest to source node on the bordercast-path from source node to a peripheral node such that its routing zone extends beyond source node’s routing zone. </li></ul><ul><li>Forwarding node: any node lying on the bordercast-path between source node and a rebordercast node. </li></ul>R=3 Forwarding node R=2 Source node R=2 Rebordercast node Peripheral nodes
  13. 13. Bordercasting Mechanism in IZR <ul><ul><li>Source node S constructs its bordercast tree. </li></ul></ul><ul><ul><li>S chooses rebordercast nodes corresponding to each of its uncovered peripheral nodes. </li></ul></ul><ul><ul><li>S then sends the query packet to each of the rebordercast nodes possibly via the forwarding nodes. </li></ul></ul><ul><ul><li>When rebordercast nodes receive query packet, they become bordercasting nodes and go back to step 1. </li></ul></ul>
  14. 14. Query Control in IZR <ul><li>The rebordercast nodes mark </li></ul><ul><ul><li>the intersection of their zone with that of the source node as covered, if the source node lies in its zone. </li></ul></ul><ul><ul><li>the intersection of their zone with that of the forwarding node(s) as covered, if the source node does not lie in its zone. </li></ul></ul><ul><li>The forwarding nodes mark their whole zone as covered. </li></ul>
  15. 15. Zone Radius Configuration <ul><li>Min Searching: Searching the minima of the IZR control traffic curve, by incrementally changing the zone radius. </li></ul><ul><li>Adaptive Traffic Estimation: Let Г be ratio of the total IERP traffic to IARP traffic for a node in an estimation interval. </li></ul><ul><ul><li>If Г >  thres x H, increase zone radius. </li></ul></ul><ul><ul><li>If Г <  thres / H, decrease zone radius. </li></ul></ul><ul><li>A hybrid of the above two heuristics is used. </li></ul>Routing Overhead R Very reactive R Very proactive Routing Overhead
  16. 16. IZR Architecture IP OSPF, OLSR, TBRPF etc. Communication Services Reliable Neighbor Broadcast Efficient Flooding BRP Efficient Probing (bordercasting) AODV, DSR, TORA etc. Routing Table IERP IARP Zone Radius Determination Route Repair-ing Route Optimiza-tion Loose Source Route Construction Route Maintenance
  17. 17. IZR Correctness Each bordercast operation covers new nodes, extending the frontier of covered nodes , eventually covering entire network in finite steps. uncovered frontier covered non-frontier covered uncovered frontier covered non-frontier covered
  18. 18. Conclusions <ul><li>The hybrid Independent Zone Routing (IZR) framework supports non-uniform, independent configurations for the nodes </li></ul><ul><li>Enables each node to dynamically and automatically configure its optimal zone radius. </li></ul><ul><li>Provides fine-tuned adaptation to spatial and temporal variations in network characteristics, improving efficiency . </li></ul><ul><li>Ability to adaptively reconfigure framework makes it robust to changes in network characteristics. </li></ul><ul><li>Adaptivity, efficiency and robustness lead to scalable routing for ad hoc networks. </li></ul>