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Meeyoung Cha and DK LeeAdvisor - Sue Moon

(Korea Advanced Institute of Science and Technology)

IEEE INFOCOM 2005 Student Workshop

Split-n-Save :Path Multiplexing in Wireless Ad Hoc Routing

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• On-demand routing is favored in resource constrained environments of wireless ad hoc network. (e.g., AODV, DSR)

• Recent routing schemes use multipath routing for fast path fail-over. (e.g., AOMDV, MDSR, NDMR, MP-DSR, SMR)

Do existing multipath routings perform well in terms of the number of active nodes over a time period or workload balancing throughout the network?

Motivation of Our Work

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Multipath Routing Basics

candidate paths

Destination

default path

Origin

Description of a typical multipath routing

1. using default path

2. failure detection

3. fast transition to one of the candidate paths

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4. using new path

Candidate paths are used only after the main path is no longer available.

Let’s use multiple paths more actively!

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• We propose Split-n-Save– Added feature to an existing multipath routing

protocol(patch to AOMDV ns-2 code)

– Use path multiplexingchange paths every k (frequency of multiplexing) packets

Expected benefits of Split-n-Save• Inherit all benefits from the underlying routing protocol• Improve routing performance

– number of active nodes over a time period– well-balanced workload throughout the network

Split-n-Save

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• To measure the efficacy, we use the following metrics.– Packet delivery ratio– Average end-to-end delay– Routing overhead

We also propose using two other metrics.– Node satisfiability :

ratio of the number of forwarding packets generated by itself and that by the other nodes

– Network survivability : number of active nodes over a period of time

Routing Performance Metrics

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• CMU wireless extensions to ns-2

Simulation Settings

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Simulation

There exists a specific k value that performs best for each routing performance metric.

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Simulation – End-to-end Delay

We find several surging points when k = 0 and 1.

surging points

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Simulation – Node Satisfiability

Node satisfiability improves when k > 0.

node satisfiability

=# of packets sent by itself

# of packet forwarded

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• For network survivability, temporal information alone was not enough. We plan to use spatial info as well.- track down the location and causality of node failure.

• For other metrics, path multiplexing clearly improves the routing performance with carefully chosen frequency of multiplexing.

Preliminary Results

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• We propose and evaluate Split-n-Save, which exploits path multiplexing in multipath routing.

• We propose two other metrics:– node satisfiability and network

survivability

• Frequency of multiplexing can be used to cope with path fail prediction and path optimality.

• Path multiplexing should reflect network dynamics.

Conclusions

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• Methodology– Probabilistic model for Split-n-Save– Other multiplexing idea– Revisit routing performance metrics for wireless

ad hoc network

• Suggestions on simulation in wireless ad hoc network– Good guideline for simulation setups– More practical movement pattern model

• Grid movement, communication on the road, campus network

Future Works