Reducing Congestion Effects in Wireless Networks by Multipath Routing
Presented by Dian Zhang
Lucian Popa, Costin Raiciu, University of California, Berkeley
ICNP 2006
Outline Problem statement and assumptions BGR congestion control mechanism
IPS EPS
Performance evaluation Conclusions
Overview
a point-to-point communication in a large Wireless Network
Overview
Overview
Goal: Split flows and reduce congestion by having less traffic in a contention/interference area.
Improve overall throughput Improve fairness
Multipath Routing-related work We need alternate paths to avoid congested
hotspots Existing solutions not satisfactory
Way pointsSimple Course Grained
Trajectory Based Forwarding [Niculescu03]Fine GrainedComplex and resource consuming
Biased Geographical Routing (BGR)
Idea Insert a “bias” inside the packet as a measure of
the deviation from the greedy path Achieve different paths by using different biases
bias = 0
small bias
large bias
BGR Details
Destinationbias1
Bias = Angle Route greedy towards a close by point projected
at “bias” angle Decrease bias at each step
Quadratic dependence on distance to destination Stop decreasing when it reaches zero
BGR Details
Destinationbias2
Bias = Angle Route greedy towards a close by point projected
at “bias” angle Decrease bias at each step
Quadratic dependence on distance to destination Stop decreasing when it reaches zero
BGR Details
Destination
bias3
Bias = Angle Route greedy towards a close by point projected
at “bias” angle Decrease bias at each step
Quadratic dependence on distance to destination Stop decreasing when it reaches zero
OverviewWe propose two algorithms to deal with congestion1. IPS - In-network Packet Scatter
Local algorithm Lightweight – no per flow state Suited for short flows or light congestion
2. EPS – End-to-end Packet Scatter End to end – rate control, relies on receiver
feedback Suited for long flows and widespread
congestion
IPS (In-network packet scatter)
Learn about congested neighbors
IPS (In-network packet scatter)
Deviate uniformly traffic to congested nodes on three paths
EPS (End-to-end packet scatter)
Source
Destination
EPS (End-to-end packet scatter)
Source
Destination
Congested node
EPS (End-to-end packet scatter)
Source
feedback
Destination
EPS (End-to-end packet scatter)
Source
Destination
EPS (End-to-end packet scatter)
Source
Central path is prioritizedDestination
Exterior paths are less aggressive than the central one
EPS (End-to-end packet scatter)
Source
Most traffic on least congested path
Destination
IPS+EPS The two algorithms can be used
Independently Combined
ns2 setup 400 nodes grid 802.11 wireless Random source-destination pairs Success measured as received number of
packets
Throughput vs Hop Count
Incr
ease
on
AIM
D(%
)
Throughput vs No. Transmissions
Testbed
Mirage sensor network testbed ~100 nodes But too “narrow” – interference on one side
Thus, our main goal was to estimate in practice potential for throughput increase
Testbed metodology Throughput of
vs
Testbed results
Rate LQI 80 LQI 82 LQI 84 LQI 86
40 packets/s 167 11 72 4233 packets/s 120 -12 17 -820 packets/s 93 -3 -2 -12
% Increase in received packets for two BGR paths of 40 degree bias compared to single paths
Conclusions BGR
An efficient and practical multipath algorithm for wireless networks with location information
IPS, EPS Two mechanisms to increase fairness and
throughput by multipath routing Practical tests
Thank you!Thank you!
ICNP 2006ICNP 2006
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