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

4

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?

6

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)

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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

8

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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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Plasma Routing

Distributed and optimal routing algorithm Generalization of the Bellman-Ford algorithm Run time of

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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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Each gateway d assigned a non-zero cost

Higher cost has a back-pressure effect

Load Balancing

12

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IEEE 802.11a Path-loss and SNIR models for the PHY layer 500x500 m2 grid topology with 11x11 nodes

Simulation Scenario

13

Plasma Throughput

14

98%

2.9x

5.6x

Plasma End-to-End Delay

15

2.5x

2.2x

5.4x

Different Uplink Bandwidths

16

1 Mbps

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

17

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