Congestion control in wireless networks pac perceptive admission control protocol
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Congestion Control In wireless Networks [ PAC: Perceptive Admission Control Protocol]. Goal. Control the amount of traffic in the network Provide high quality service to all admitted traffic Ensure the network congestion point is not reached. Background: Impacted area.

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Congestion Control In wireless Networks [ PAC: Perceptive Admission Control Protocol]

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Congestion control in wireless networks pac perceptive admission control protocol

Congestion Control In wireless Networks[PAC: Perceptive Admission Control Protocol]


Congestion control in wireless networks pac perceptive admission control protocol

Goal

  • Control the amount of traffic in the network

  • Provide high quality service to all admitted traffic

  • Ensure the network congestion point is not reached


Congestion control in wireless networks pac perceptive admission control protocol

Background: Impacted area


Congestion control in wireless networks pac perceptive admission control protocol

Background: Impacted area

  • How is Reception Range defined

    • the maximum separation between a sender and receiver for successful packet reception as RxR.


Background receiver interference distance rid

Background: Receiverinterference distance (RID)

  • CSR>RID>RxR


Congestion control in wireless networks pac perceptive admission control protocol

Background

  • The distance between two senders to ensure proper packet reception at a receiver is RxR + RID.

  • This distance holds for all possible network scenarios. At any distance smaller than RxR + RID, it is possible that the transmissions of two senders will interfere with a receivers ability to properly decode a packet.


Congestion control in wireless networks pac perceptive admission control protocol

Background

  • The safe distance between two senders is 2RxR+RID


Congestion control in wireless networks pac perceptive admission control protocol

Determining the Available Bandwidth

  • MAC Layer Congestion Window

  • Queue Length

  • Number of Collision

    These methods provide little or no information regarding network utilization if a node is not actively transmitting packets.


Determining the available bandwidth

Determining the Available Bandwidth

  • Channel Busy Time

    • Transmitting

    • Receiving

    • Busy

  • The total time within an interval that a node is transmitting packets,receiving packets or sensing packet transmissions.


Perceptive admission control

Perceptive Admission Control

New CSR

  • A sender can consider only the traffic within this new CSR before admitting a new traffic


Contention aware admission control protocol cacp

Contention-Aware Admission Control Protocol (CACP)

A query message must be sent to all nodes within carrier sensing range.

If all CSN detect enough available bandwidth

then the flow is admitted.


Congestion control in wireless networks pac perceptive admission control protocol

Query flooding may fail

  • S2 is an isolated node, but it does affected by the new traffic brought by S1

  • Solution: use high power packet transmission to send the query message


Contention aware admission control protocol cacp v s pac

Contention-Aware Admission Control Protocol (CACP) V.S. PAC


Perceptive admission control1

Perceptive Admission Control

  • To prevent the channel congestion, PAC ensures that the quantity of admitted traffic is below the network saturation point by reserving a small portion of the bandwidth.

  • This prevents the channel from becoming congested and allows all admitted traffic to receive high delivery rates and low delay.


Congestion control in wireless networks pac perceptive admission control protocol

Mobility

  • What would happen if two sender-receiver pairs move closer than the safe range

?

75%

75%


Mobility

Mobility

  • Each source monitors the available bandwidth

  • Senders check available bandwidth after a random time and before sending a packet

  • Random back-off time


Congestion control in wireless networks pac perceptive admission control protocol

Advantage

  • PAC does not send query message, thus reduce the query overhead.


Conclusion

Conclusion

  • PAC effectively limits the amount of data traffic to avoid congestion

  • Provides consistent throughput, low packet loss and delay

  • Useful in wireless application that requires high QoS such as multimedia applications


Congestion control in wireless networks pac perceptive admission control protocol

Questions..?


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