1. A Proximity-based Routing Protocol for Wireless Multi-hop Networks
Tokuda Lab. Keio Univ.
Masato Saito

2. Introduction About Ad hoc Network Current Problem
DoCoMo成果発表
Introduction
About Ad hoc Network
Current Problem
Solution: Optimized Re-Routing (OR2)
Main
Evaluation
Experiments
Simulation
Conclusion and Future Work

3. Mobile Ad Hoc Networks → Formed by wireless hosts which may be mobile
Introduction
DoCoMo成果発表
Mobile Ad Hoc Networks
Formed by wireless hosts which may be mobile
Without (necessarily) using a pre-existing infrastructure
Routes between nodes may potentially contain multiple hops
Node Mobility causes route changes →
Ease of deployment, Speed of deployment,
Decreased dependence on infrastructure

4. Many Applications Personal area networking Military environments
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Many Applications
Personal area networking
cell phone, laptop, ear phone, wrist watch
Military environments
soldiers, tanks, planes
Civilian environments
taxi cab network
meeting rooms
Robot network
Emergency operations
search-and-rescue
policing and fire fighting
ITS & Sensor Networks

5. An Application Scenario
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An Application Scenario
Cellular and BS BS
Cannot connect to
BS directly.
Using multi-hop
Connection to BS A B

6. Many Protocols Proposed …
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Many Protocols Proposed …
ＤＳＲ　　　----- On-demand Source Routing
ＡＯＤＶ On-demand Table Driven
ＬＡＲ GPS-based Routing
ＺＲＰ Proactive Zone Routing, Hybrid
→　But, these protocols mainly focus on connectivity and route discovery.
Previous protocols realize efficient connectivity?

7. Problems of Conventional protocols
Problem Definition
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Problems of Conventional protocols
Not identify the nearness of two nodes For example,
Never change the route unless the links fails, So ….. 1 2 3
シナリオ

8. Effect of Path Shortening
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Effect of Path Shortening
DSR ( on FreeBSD,
5 Laptops with b NICs

9. DoCoMo成果発表
OR2 Solution
Estimates the change of network topology (the nearness of two nodes) based on the local link state of SNR
Re-routes the path adaptive to node mobility when the links are still active.
　Optimized Re-Routing（OR2） 1 2 3

10. Proximity : to identify the nearness
OR2 Solution
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Proximity : to identify the nearness
The area around Node A where the received SNR value is more than a threshold.
suppose that Node A and B are the same location if Node B is in the proximity of A. A B
Proximity of Node A
Cell
We assume that all nodes
in a network. Have the same NIC.

11. One-hop path shortening
Proximity of Node C A B C
C∈P(B)
flow
Proximity of Node A
movement
Proximity of Node B
IF S(bc) > Smax
THEN C∈P(B)
C sends REQ to A
A sends DATA to C
S(bc) is the received SNR value of C.
Smax is the threshold of proximity.
P(B) is the proximity of Node B.
S(bc) = S(cb)
Symbol Definition

12. DoCoMo成果発表
Exclusive Control
the cases that neighbor nodes initiate shortening the same path….. C
flow
time
OR2_REQ
OR2_REP
OR2_RREQ
Shorten route
SSNR > Smax
SSNR > Smin
Smax > Smin B A B C D E F A

13. DoCoMo成果発表
OR2 features
Local Decision using local link quality obtainable from own NIC.
No periodic control packets.
Network bandwidth, interference, power consumption
By the Iteration of one hop shortening, we can shorten any hop route as possible.
Applicable to previous routing protocols.
Simple.

14. Evaluation by simulation
Simulation Parameters
1500 m x 300 m, flat field, 50 mobile nodes.
Speed uniformly distributed between 0 – 20 m/sec.
Constant Bit Ratio UDP traffic (512 packet).
Five runs with different mobility scenarios
Variable
The number of traffic sources
Node Mobility Model (& Node Pause Time)
Evaluation Metric
Average Data Packet Delay
Packet Delivery Ratio (PDR)
Normalized routing overhead

15. Classified Mobility Models
Random Way-Point Mobility
Our Random Oriented Mobility
Makes some node congestion points.
This model is favorable for OR2.
Our Random Escape Mobility
Makes some network partition areas intentionally.
Heavy loads to OR2.
dst
dst
Select a random destination in the specified field space and moves to the destination at a speed distributed uniformly between 0 and some maximum speed. On reaching the destination, the node pauses again for pause time seconds, selects another destination.

16. Random Oriented Mobility Model
Core Nodes
Oriented Nodes 1 2 3 4 5 6
Random Escape Mobility Model
Core Nodes
Escape Nodes 1 2 3 4 5 6

17. Evaluation: 10 sources Avg. Delay Packet Delivery Ratio
Routing Overhead
Packet Delivery
Ratio

18. Evaluation: 30 sources Avg. Delay Packet Delivery Ratio
Routing Overhead
Packet Delivery
Ratio

19. Evaluation: in Oriented Mobility
Avg. Delay
Routing Overhead
Packet Delivery
Ratio

20. Simulation Results Summary
OR2 improves the end-to-end delay as expected and reduces the routing control packet overhead effectively.
In the packet delivery ration (PDR) of light traffic load scenario , OR2 loses about 5 % packets.
In heavy traffic loads, OR2 has the highest performance of PDR.
AODV with OR2 does not show the improved performance as salient as DSR with OR2.
In our Random Oriented Mobility, we can see that the improved delay reduction is significant.

21. Implementation in our testbed
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Implementation in our testbed
As an extension to DSR on FreeBSD-4.4R
SNR (from NIC driver) monitoring module
OR2 routing table to maintain the upstream two-hop-away node’s information
OR2 control packet for path shortening
Using MELCO b NICs 　

22. Latency of Path Shortening
Evaluation
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Latency of Path Shortening
Shortening time is the order of 10 ms.
It is suitable for slow mobility (pedestrians and slow vehicle) Ｂ Ｃ Ａ Ｃ Ｂ Ａ

23. Future Works Simulation analysis.
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Future Works
Simulation analysis.
Development of Signal power and supplemental location information based Wireless Routing Protocol in our testbed (iPAQs running Linux).
Design of Transport protocol for Ad Hoc Networks.
Simulation evaluation in popular b & a wireless LAN environments (in this work, we used [2Mbps] wireless LAN Network).

24. Today’s Summary
We proposed Proximity-based Re-Routing Algorithm for Mobile Ad Hoc Networks.
OR2 dynamically shortens active paths based on the proximity.
Previously proposed routing protocols (e.g., DSR & AODV) were effectively enhanced by OR2.
OR2 remarkably reduced the routing packet overhead and data packet latency.

25. Publications DoCoMo成果発表
M. Saito, H. Aida, Y. Tobe, Y. Tamura, and H. Tokuda　　　"A Dynamic Path Shortening Scheme in Ad Hoc Networks",情報処理学会 マルチメディア通信と分散処理ワークショップ (DPS)、2001年１０月、
Winner of the Best Presentation Award
and Winner of the Young Researcher’s Award
M. Saito, H. Aida, Y. Tobe, Y. Tamura, and H. Tokuda　"OR2: A Path Tuning Algorithm for Routing in Ad Hoc Network”, IEEE LCN on Wireless Local Networks (WLN), Tampa, FL, Nov

26. DoCoMo成果発表
FIN
Masato Saito, Tokuda Lab., Keio Univ.

28. Multi Hop Shortening

29. Evaluation: 10 sources Avg. Delay Packet Delivery Ratio
Routing Overhead
Packet Delivery
Ratio

30. Evaluation: in Escape Mobility
Avg. Delay
Routing Overhead
Packet Delivery
Ratio