Proposed ad hoc Routing Approaches

1. Proposed ad hoc Routing Approaches • Conventional wired-type schemes (global routing, proactive): • Distance Vector; Link State • Proactive ad hoc routing: • OLSR, TBRPF • On- Demand, reactive routing: • DSR (Source routing), MSR • AODV (Backward learning) • Scalable routing : • Hierarchical routing: HSR, Fisheye • OLSR + Fisheye • LANMAR (for teams/swarms) • Geo-routing: • GPSR, GeRaF, etc • Motion assisted routing

2. Georouting - Key Idea • Each node knows its geo-coordinates (eg, from GPS or Galileo) • Source knows destination geo-coordinates; it stamps them in the packet • Geo-forwarding: at each hop, the packet is forwarded to the neighbor closest to destination • Options: • Each node keeps track of neighbor coordinates • Nodes know nothing about neighbor coordinates

3. Greedy Perimeter Stateless Routing for Wireless Networks (GPSR)– key elements • Greedy forwarding • Each nodes knows own coordinates • Source knows coordinates of destination • Greedy choice – “select” the most forward node

4. Finding the most forward neighbor • Beaconing: periodically each node broadcasts to neighbors own {MAC ID, IP ID, geo coordinates} • Each data packet piggybacks sender coordinates • Alternatively (for low energy, low duty cycle ops) the sender solicits “beacons” with “neighbor request” packets

5. Greedy Perimeter Forwarding D is the destination; x is the node where the packet enters perimeter mode; forwarding hops are solid arrows;

6. Got stuck? Perimeter forwarding> Greedy forwarding failure. x is a local maximum in its geographic proximity to D; w and y are farther from D.> Node x’s void with respect to destination D

7. GPSR vs DSR

8. TCP over GPSR, AODV, DSR and DSDV Throughput (Kbps) Speed(m/s)

9. Hot spot Congestion Aware GPSR Problem: Congestion area will cause long packet delay and high loss probability Our approach: • Go around the congestion area will decrease the delay, but detour path is usually longer than the shortest path. Going through the long path will cause throughput loss. • Study packet delay, the tradeoff between congestion detour and throughput gain.

10. GPSR commentary • Very scalable: • small per-node routing state • small routing protocol message complexity • robust packet delivery on densely deployed, mobile wireless networks • TCP is extremely sensitive to path breakage (timeout) -- It does very well with georouting • Outperforms DSR and AODV • Drawback: it requires knowledge of dest geo coordinates (explicit forwarding node address) • Beaconing overhead • nodes may go to sleep (on and off) in sensor networks