1. Tiny Ad hoc Routing Protocol (TARP) Ashikur Rahman and Pawel Gburzynski Department of Computing Science University of Alberta Email: ashikur@cs.ualberta.ca

2. Features & Assumptions Controlled Flooding as a routing scheme Simple Flexible Low cost No control packets Some tunable parameters Fixed communication range Bi-directional flows

3. Protocol in Brief Reactive Broadcast-based Converge to a narrow strip of nodes along the shortest path S D

4. Two controlling rules Duplicate Discard (DD) rule Retransmission Count Source ID Sequence no Session ID Destination ID Packet signature Packet Header, Packet signature + r + h + some more fields

5. Packet signatures are stored in DD Cache. First Rule (Cont.) Expiry time of an entry, T r Average transmission time, t avg Initially

6. Second Rule Sub Optimal Path Discard (SPD) rule Has it’s own (SPD) cache Each entry is a tuple, Discard Counters Hop count between Target Avoid forwarding via sub- optimal path

7. Second Rule (Cont.) h SK h DK hbhb S K D Number of Packets to be discarded by K, m b is called mobility factor Value of m b indicates aggressiveness

8. Example: SPD Rule. S K L M D Z SPD Buffer at: hbhb mbmb D00 S00 SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M000000 L000000 K000000 Z000000

9. Packet P1 from D to S S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M000010 L000020 K000030 Z000010 SPD Buffer at: hbhb mbmb D00 S21

10. Packet P2 from S to D S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M213210 L212220 K211230 Z211010 SPD Buffer at: hbhb mbmb D21 S21

11. Packet P3 from D to S S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M213212 L212222 K211232 Z211010 SPD Buffer at: hbhb mbmb D21 S21

12. Packet P4 from S to D S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M213212 L212222 K211232->1 Z211010 SPD Buffer at: hbhb mbmb D21 S21

13. Packet P5 from D to S S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M2132->112 L212222 K211231 Z211010 SPD Buffer at: hbhb mbmb D21 S21

14. Packet P6, P7 S K L M D Z SPD Cache at x: hbhb mbmb h SX C DS h DX C SD M213012 L212222 K211230 Z211010 SPD Buffer at: hbhb mbmb D21 S21

15. Second Rule (Cont.) Can be best viewed as series of light bulbs. Nodes on shortest path always turned on Nodes on sub optimal path are periodically turned on/off Frequency of turning on/off varies. S D

16. Second Rule (Cont.) Lower value of m b will cause more flooding. Higher value of m b will narrow down the width of the forwarding node strip. Dynamic quantity The constant need not to be static

17. Experimental Result

18. Couple of MAC Issues Hidden Node Problem A B C Four way handshake RTS/CTS/DATA/ACK ineffective. Does not even use two-way handshake DATA/ACK. Without feedback retransmission is impossible.

19. Fuzzy Acknowledgement Sender will reserve bandwidth for a duration of: –SIFS + ACK tx time Recipient of the packet will send ACK after SIFS Thus Multiple recipients will be allowed to send ACK almost at the same time. Exactly 3 things can happen –No activity –A valid ACK –A short period of burst activities Fuzzy ACK not vary reliable, merely gives a hint.

20. Sample Scenario

21. Cross Layer Interaction For Recipient MAC  Should I send ACK? For Sender MAC  Should I retransmit? Retransmission decision is done statistically: RF related to probability of lying on the optimal path If RF > RF threshold  retransmit.

22. Effect of RF threshold

23. Performance Improvement

24. Future Direction Solution to Hidden node problem yet to be uncovered. Incorporation of power consumption into heuristics facilitating path identification.

25. Question/Comment