Transcript Distributed Hop-by-Hop Rate Adjustment for Congestion Control in Sensor Networks Presented by: Manmohan Voniyadka Sapna Dixit Vipul Bhasin Vishal Kumar Singh.

Distributed Hop-by-Hop Rate
Adjustment for Congestion
Control in Sensor Networks
Presented by:
Manmohan Voniyadka
Sapna Dixit
Vipul Bhasin
Vishal Kumar Singh
Agenda
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Problem description
Solution requirements
Algorithm description
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Congestion pricing scheme
Rate adjustment using price of congestion
Protocol details
Open Issues
Schedules and Work Distribution
Problem Description
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Rate Adjustment to avoid congestion
Calculation of congestion pricing via a
distributed mechanism
Solution Requirements
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Develop a congestion pricing scheme
Develop a relationship between rate
and the congestion pricing.
Modify CODA Protocol to incorporate
these changes
Congestion Pricing Scheme
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Factors for pricing
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MAC utilization.
Congestion Price at Downstream Nodes.
Calculate a cumulative congestion pricing
factor.
Calculate pricing factor in a distributed
manner.
Weigh the pricing on congestion nodes
appropriately.
Congestion Pricing Calculation
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Cumulative Congestion Pricing:
N
pj 
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 w cp
i
i
1
N
wi – relative weight of downstream
node, i
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wi =
 i 1
cpi  
cpi 1
 i 
N is the Nth node from the congested node
cpi congestion pricing at the ith node
pj is a marking function (As given in [1])
Rate Adjustment Using
Congestion Pricing
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Rnew
Use an AIMD Strategy:
 cpcurr  cp prev 
 1 
 Rcurr for cpcurr  cpprev
cp prev


Rnew  Rcurr  X, X  f(cpcurr , cpnew ) for cpcurr  cpprev
Protocol Details
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Conditions for Backpressure Origination
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Header Format Changes
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Send backpressure when threshold is
exceeded as done in CODA
Threshold based on channel sampling
Extra field for price of congestion value in
backpressure messages
End-to-End Loop Control
Open Issues
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Relative weight in Congestion pricing is only
based on congestion price at downstream
nodes, Need to add Transmission rate at ith
node as factor in weight.
Whether to use price of congestion for end to
end loop control for controlling the source
rate during persistent congestion.
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What happens with Asymmetric links ?
Changes to existing CODA
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Changes in Suppression Message
generation.
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Threshold based on MAC Utilization /
channel Sampling.
Calculate and Send Congestion Price.
Changes in ReceiveBackPressure
Message -> AdjustSourceRate.
Glossary
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CPj = P (j) * MAC Utilization (j).
CPj is the congestion price for using node j per unit time.
P(j) is the marking function at node j and determines the fraction
of flow to be marked.
MAC Util is the fraction of time node j spends in receiving and retransmitting to next hop.
P (j) = P (j) = (y - tj) / y
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y is sum of MAC utilization time by all flows at node j.
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tj is a parameter for controlling MAC time utilization.
P (j) indicates fraction of flow exceeding the threshold parameter. If
link quality is bad , We make tj << 1 for lower MAC time utilization.
References
[1] Chieh-Yih Wan, Shane B. Eisenman and Andrew T.
Campbell, “CODA: Congestion Detection and
Avoidance in Sensor Networks”, ACM SenSys 2003,
November 2003.
[2] Y. Yi and S. Shakkottai. Hop-by-hop Congestion
Control over a Wireless Multi-hop Network,“ IEEE
INFOCOM, 2004.