| Conference Paper |
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| Title |
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ProbeCast: MANET Admission Control via Probing
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| Abstract |
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An inelastic flow is a flow with inelastic rate: i.e., the rate is
fixed, it cannot be dynamically adjusted to traffic and load
condition as in elastic flows like TCP. Real time, interactive
sessions and video/audio streaming are typical examples of
inelastic flows. Reliable support of inelastic flows in wireless
ad hoc networks is extremely challenging because flows and routes
dynamically change and flows compete for the shared wireless
channel. Bandwidth must be reserved for inelastic flows at session
set up time. To avoid repeated attempts to set up reservations in
a "volatile" network and prevent serious network capacity
degradation due to call set up overhead, a Call Admission Control
strategy robust to mobility must be developed. In this paper we
propose ProbeCast, a probe based call admission control scheme
with QoS guarantees for inelastic flows. ProbCast was designed for
multicast streams but can also work, by default, for unicast. In
ProbeCast, a path (or a tree) is probed for capacity availability.
If an intermediate link along the probed path fails to meet the
QoS requirement, the flow is ``pushed back'' via backpressure
upstream to the source. The backpressure principle is simple;
however its implementation requires some care to avoid unfairness
and eventually capture by one of the flows sharing a congested
bottleneck. We show that proportional fairness among inelastic
contenders will prevent capture. To achieve this, we have
developed the Neighborhood Proportional Drop (N-PROD) scheme.
N-PROD guarantees the same proportional drop rate among all flows
competing in the same contention domain. We demonstrate the
efficacy and robustness of ProbeCast for unicast as well as
multicast scenarios using the Qualnet simulation platform.
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| Download |
Paper: PDF file of paper
Slides: PPT file of slides
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| Information & Date |
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Q2SWiNet, Vancouver, BC, Canada, October. 2008
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| Authors |
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Soon Young Oh
Gustavo Marfia
Mario Gerla
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