1. Ordering in Time: A New Routing Approach for Wireless Networks Stephen Dabideen and J.J. Garcia-Luna-Aceves Department of Computer Engineering University of California, Santa Cruz MASS 2010

2. Outline  Introduction  Related Work  TORP(Time-Based Ordering for On-Demand Loop-Free Routing)  Performance  Conclusion

3. Introduction  Many routing approaches have been proposed for routing in wireless networks over the past 40 years  Most has focused on the ordering of nodes with respect to destinations using spatial information, such as Distances to destinations, Absolute location of nodes, Relative location with respect to special nodes  While shortest path routing works well in wired networks, it is not very efficient in wireless networks especially in the face of mobility.

4. Related Work  Spatial ordering AODV [18], DSDV [17] [18] C. E. Perkins and E. Royer. Ad hoc on-demand distance vector routing. In Proceedings of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, pages 90–100, February 1999. ABC S D [17] C. E. Perkins and P. Bhagwat. Highly dynamic destination-sequenced distance-vector routing (dsdv) for mobile computers. In Proceedings SIGCOMM ’94, pages 234–244, August 1994. Link quality  Distance  Network congestion Multiple paths  Delivery ratio

5.  Spatial ordering ETX [6] Related Work ABC S D Hop count =1 Hop count =0 Hop count =2 [6] D. D. Couto, D. Aguayo, J. Bicket, and R. Morris. A high-throughput path metric for multi-hop wireless routing. Proc. MobiCom, 2003. Heavy load and low mobility.

6.  Spatial ordering GPSR [10] Related Work ABC S D Hop count =1 [10] B. Karp and H. Kung. Greedy perimeter stateless routing for wireless networks. Proceedings of the Sixth Annual ACM/IEEE International Conference on Mobile Computing and Networking, pages 243–254, August 2000. Local minima Knowing the position of the destination beforehand remains a critical assumption

7. The Temporal Ordering Routing  We advocate the use of a temporal ordering as an alternative to the spatial orderings used in most routing protocols.  We propose the use of ordering of nodes based on time rather than space Without the need to establish any clock synchronization among nodes.

8. TORP  Time-Based Ordering for On-Demand Loop-Free Routing Route Request Phase Route Replay Phase S AB D RREQ RREP

9.  Route Request Phase TORP A B TATA TBTB RARA RBRB Definition 1: Node A is a successor of Node B on a path to destination C if or if A is the destination. is the local time node B received a RREQ from  is the local time at which node  retransmitted the RREQ. as an upper bound on the transmission and propagation delay RREQ

10. TORP  Route Request Phase AB S D RREQ TSTS TATA TBTB TDTD RSRS RSRS RARA RBRB RBRB RBRB RDRD RARA RDRD RARA Definition 1: Node A is a successor of Node B on a path to destination C if or if A is the destination.

11. TORP  Route Replay Phase AB S D RREQBA C BD RREP Definition 2: The Reply Acceptance Condition (RAC): A node can only accept and process a RREP if it is received from a successor, as defined in Definition 1.

12. TORP  Route Maintenance When a link fails, a node can route data through any of its neighbors as long as they are successors As long as the destination is receiving packets, it periodically initiates proactive updates S AB D

13. TORP  Adjustable Ordering and Mobility in TORP Nodes attempt to adjust the ordering of their neighbors so that they have almost equal number of successors and predecessors. This is done by adjusting the time at which they retransmit RREQs. A

14. TORP  The advantages of time-based temporal ordering over spatial ordering in the design of routing protocols, such as Allowing more paths, Factoring in network conditions implicitly, To be efficient under heavy load and high mobility.

15. Performance AODVAODV uses hop counts and destination-based sequence numbers to establish spatial ordering of nodes along a single path between the source and the destination. IEEE Workshop on Mobile Computing Systems and Applications, 1999 DYMODYMO improves over AODV with the use of path vectors to make the protocol more resilient to path failures. IETF Internet Draft, 2008 CaSHCaSH establishes multiple paths from the source to the destination in an on-demand manner and proactively updates the multi-dimensional ordering of nodes ANC 2008 IEEE Workshop

16. Performance ARANARAN seek to add security to the protocol by eliminating a need for recorded distances. In ARAN, packets are routed along the quickest path from the source to the destination. This ordering, however, only creates a single path and would be strongly co-related to a distance based ordering such as AODV. International Conference on Network Protocols, 2002. OLSROLSR is a link state routing protocol where all nodes attempt to maintain up-to-date routing information to all other nodes in the network. RFC 3626, October 2003. DSR'Dynamic Source Routing' (DSR) is a routing protocol for wireless mesh networks. It is similar to AODV in that it forms a route on-demand when a transmitting computer requests one. However, it uses source routing instead of relying on the routing table at each intermediate device. IAd Hoc Networking, chapter 5, pages 139–172. Addison- Wesley, 2001.

17.  The simulations were performed using the Qualnet 4.5 network simulator. Performance

19. Conclusion  We introduced the Time Ordered Routing Protocol (TORP) as an example of the potential of this new type of ordering  We have described the inherent advantages of temporal ordering over spatial ordering in the design of routing protocols  We showed that it performs better than the traditional approaches based on spatial ordering.