1. Pune, India, 13 – 15 December 2010 ITU-T Kaleidoscope 2010 Beyond the Internet? - Innovations for future networks and services Guowei CHEN GITS, Waseda University, Tokyo JP. davidchen@aoni.waseda.jp A scheme for Disaster Recovery in Wireless Networks with Dynamic Ad-hoc Routing

2. Self Introduction 2000 - 2003 Master – Sun-yetsen Univ., China 2003 – 2006 WCDMA, NORTEL, G.D. China 2006 – now Doctor course, RA, Waseda Univ., Japan Interests: WMN, P2P

3. Pune, India, 13 – 15 Dec 2010: ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services 3 Before Disaster Research Background BS CS backbone BS Mobile node

4. Pune, India, 13 – 15 Dec 2010: ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services 4 After Disaster Research Background (cont.) ad-hoc mode cellular mode damaged BS CS backbone

5. Pune, India, 13 – 15 Dec 2010: ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services 5 How to route to a BS? Problem to solve S B C2 C1 G BS

6. Presumptions After disaster, mobile nodes of a cell are operational (even the BS is down). A mobile node has two interfaces for Cellular connection Ad-hoc connection A node knows its location (via GPS) A node knows location of BSs (pre- stored)

7. Beaconing Routing Periodic broadcast Route table not always updated

8. Beaconless Routing AP search Procedures: Achieves own location via GPS Finds out near-around BSs or moving TRs. Go thru all the above BSs or TRs, from close to far. For each a BS or TR, performs BLR routing.

9. Beaconless routing (cont.) S A3 A4 A2A2 A1A1 E D G BS β=60° Steps of routing: (S -> D) S broadcasts a packet, and all the neighbors (within radius r) can receive it (A1, A2, A3, A4). But only the neighbors within the 60°sector schedules a packet forward (A1, A2) A1, A2 performs a DFD (Dynamic Forward Delay) mechanism or

10. Simulation Model node working as gateway node in ad-hoc mode test area working antenna Randomly selected broken antenna Moving Terminal Repeater

11. Metrics IDCNR = m1 / N where m1 is the number of nodes initially have direct connection to a BS, and N is the total number of the nodes in the test area. Reachability Reachability is defined as the ratio of the nodes that are able to reach BS directly or by multi-hopping Relative Node Density (RND) a relative node ratio is defined as follows. If a certain number of nodes are arranged in grid in the test area, and the grid interval is exactly the same as communication range, the certain number is noted as K. And RND is defined as RND = N / K. Average Re-send Times (AR) If a next hop is not found, the packet has to be re-sent. AR is the average number of times of re-sending a packet.

12. Results Even IDCNR is fairly low (e.g.0.3), most nodes can reach a BS within 4 hops.

13. Results (2 ） A relatively low Node Density can provide a fairly good reachability. E.g. when RND is 0.5, Reachability is over 0.7

14. Result (3) As speed increases, Beaconing protocol is affected more significantly than the Enhanced-BLR protocol

15. Conclusion This paper has proposed a location-based ad-hoc routing protocol used in a hybrid wireless system. The focus is to maintain connectivity in the aftermath of a disaster. Simulation results shows that even only a small part of the nodes can directly connect to a BS, but most nodes can route to a BS. It outperforms the Beaconing protocols in terms of resistance to mobility.

16. Questions