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PLASMA: A New Routing Paradigm for Wireless Multihop Networks
R. Laufer1 P. Velloso2 L. Vieira3 L. Kleinrock1
1University of California, Los Angeles 2Universidade Federal Fluminense
Los Angeles, USA Niteroi, Brazil
3Universidade Federal de Minas Gerais
Belo Horizonte, Brazil
Multiple Gateways
Total load directed to the lowest-cost gateway Current routing models limited to unicast delivery Prevents simultaneous use of multiple gateways Fairness and under-utilization issues
Internet
2
Gateway
Gateway
Gateway
Our Contributions
New routing paradigm for wireless networks Internet traffic can be delivered to any gateway Network decides both the path and gateway on the fly
Optimal polynomial-time routing algorithm Load balancing
Load split among different gateways via anycasting Technique for different gateway uplink bandwidths
3
Anycast Forwarding
Packet broadcast to multiple nodes simultaneously High chance of at least one node receiving it Node with the lowest cost forwards it on Coordination with overhearing or ACK channels
Time
SN
IR
Time
SN
IR
Time
SN
IR
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Plasma Routing
Every node forwards packets to a set of nodes Directed acyclic graph (DAG) to the gateways This DAG is called a plasma path
5
s
d1
d2
d3
Plasma Routing Challenges
Forwarding set selection Few neighbors: lower receiver diversity Many neighbors: potentially higher costs
Rate selection Lower rates: lower loss, longer range, less hops Higher rates: higher loss, shorter range, more hops
Gateway set selection More gateways do not always reduce the routing cost
How to choose the optimal tradeoff point?
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Plasma Path Cost
What is the cost of a plasma path? Similar to the cost in anypath routing* Composed of two different components
Hyperlink cost Remaining cost
diJ(r) DJ
(r)
diJ(r)
DJ(r)
i
J
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d1
d2
* R. Laufer et al. “Multirate Anypath Routing in Wireless Mesh Networks”, INFOCOM’09 R. Laufer et al., “Polynomial-Time Algorithms for Multirate Anypath Routing in Wireless Multihop Networks”, IEEE/ACM ToN
Plasma Cost Example
Cost calculation
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JiJi DdD
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4.1)2.0)(3.01(1.1)3.0(
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1
5.32.13.2
Plasma Cost Calculation
Is it better to use more nodes/gateways? No! Additional node always decreases hyperlink cost May increase remaining cost
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1.4?
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i
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d20
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Plasma Routing
Distributed and optimal routing algorithm Generalization of the Bellman-Ford algorithm Run time of
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d2
d3
)log( VVEVERO .4
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∞
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0
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∞
∞
10.9
2.7
1.6
2.7
5.5
3.0
3.6
5.7
6.5
3.3
5.6
Load Balancing
Plasma already has some intrinsic load balancing Gateway d1 receives of the traffic
Gateway d2 receives of the traffic
In general, a gateway d receives Load depends on delivery ratios
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%53ilw
i
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.2
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d1
d2
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Each gateway d assigned a non-zero cost
Higher cost has a back-pressure effect
Load Balancing
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5.6
6.5
02.7
1.6
0
2.7
5.5
3.0
3.3
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d1
d2
d3
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10.67
IEEE 802.11a Path-loss and SNIR models for the PHY layer 500x500 m2 grid topology with 11x11 nodes
Simulation Scenario
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Conclusions
Plasma routing Generalization of anypath routing to anycast delivery Optimal polynomial-time distributed routing algorithm
Load balancing for different uplink bandwidths Simulation results
98% throughput gain and 2.2x delay decrease Load balancing gives additional 63% throughput gain
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