5. A Mobile Ad Hoc Network Symmetric link Asymmetric link MS3 MS2 MS4 MS1 MS5 MS6 MS2 MS7

13. Routing in CGSR from node 1 to node 8 CGSR (Cont’d) 1 3 2 4 7 10 5 6 8 9 11 12 Cluster Head Internal Node Gateway Node

18. Route Discovery in AODV Protocol Source Destination 1 3 2 5 7 4 6 8 (a) Propagation of Route Request (RREQ) Packet Source Destination (b) Path Taken by the Route Reply (RREP) Packet 1 3 2 5 7 4 6 8 Hop1 Hop2 Hop3

21. Hop1 Hop2 Hop4 Hop3 Source Destination <1> <1> <1,2> <1> <1,3> <1,3,5> <1,3,5,7> <1,4> <1,4,6> (a) Building Record Route During Route Discovery 4 1 4 6 8 7 2 3 Source Destination <1,4,6> <1,4,6> <1,4,6> (b) Propagation of Route Reply with the Route Record 1 2 3 5 6 7 8 Creation of Route Record in DSR 1 4 7 5 3

23. Illustration of Tora height metric Source Destination H = 0 H = 1 H = 2 H = 3 TORA (Cont’d)

25. Source Destination Destination Source Figure 13.6(a) – Propagation of the query message Node’s height updated as a result of the update message TORA (Cont’d) 1 2 3 4 5 6 7 8 (-,-) (-,-) (-,-) (-,-) (-,-) (-,-) (-,-) (0,0) 1 2 3 4 5 6 7 8 (0,3) (0,1) (0,1) (0,2) (0,2) (0,3) (0,3) (0,0)

30. Protocol Characteristics (1/2) Route error propagated up to the source to erase invalid path Not explicitly. The technique of salvaging may quickly restore a route Yes Yes. Aggressive use of caching may reduce flood On-demand, only when needed DSR Ultimately, updates the routing tables of all nodes by exchanging MRL between neighbors No No No Computed a priori WRP Updates the routing tables of all nodes No No No Computed a priori DSDV Effect of Route Failure Multipath Capability Delay for Route Discovery Flood for Route Discovery Route Acquisition Routing Protocol

31. Protocol Characteristics (2/2) Hybrid of updating nodes' tables within a zone and propagating route error to the source No Only if the destination is outside the source's zone Only outside a source's zone Hybrid ZRP Route error propagated up to the source No Yes Reduced by using location information On-demand, only when needed LAR Error is recovered locally Yes Yes. Once the DAG is constructed, multiple paths are found Basically one for initial route discovery On-demand, only when needed TORA Route error propagated up to the source to erase invalid path No, although recent research indicate viability Yes Yes. Controlled use of cache to reduce flood On-demand, only when needed AODV Effect of Route Failure Multipath Capability Delay for Route Discovery Flood for Route Discovery Route Acquisition Routing Protocol

39. Base Station 3 3.1 3.2 3.3 2 2.1 2.2 2.3 1 1.0.1 1.0.2 1.0.3 1.2 1.2.5 1.2.4 1.2.3 1.2.2 1.2.1 1.1 1.1.3 1.1.4 1.1.5 1.1.1 1.1.2 Simple sensor node First Level Cluster Head Second Level Cluster Head Hierarchical Routing (Cont’d)

43. Time Line for TEEN Reactive Network Protocol:TEEN Cluster Formation Cluster Change Time Parameters Cluster Head Receives Message Attribute > Threshold

47. Time line for APTEEN Adaptive Periodic Threshold-sensitive Energy Efficient sensor Network protocol (APTEEN) Frame Time Cluster Formation Cluster Change Time TDMA Schedule and Parameters Slot for Node i

50. Hierarchical Vs Flat topologies Flat Hierarchical Contention-based scheduling Reservation-based scheduling Collision overhead present Collisions avoided Variable duty cycle by controlling sleep time of nodes Reduced duty cycle due to periodic sleeping Node on multi-hop path aggregates incoming data from neighbors Data aggregation by cluster head Routing is complex but optimal Simple but non-optimal routing Links formed on the fly, without synchronization Requires global and local synchronization Routes formed only in regions that have data for transmission Overhead of cluster formation throughout the network Fairness not guaranteed Fair channel allocation Energy dissipation adapts to traffic pattern Energy dissipation can not be controlled Energy dissipation depends on traffic patterns Energy dissipation is uniform Latency in waking up intermediate nodes and setting up the multi-hop path Lower latency as multi-hop network formed by cluster-heads is always available