PAC: Perceptive Admission Control

for Mobile Wireless Networks

Ian D. ChakeresElizabeth M. Belding-Royer

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

Background: Receiver is also a sender

CSR>RID>RxR

Background

How is RID defined? When two packets are transmitted

simultaneously, the signal power of one must be great then another by some capture factor (10)

The signal strength of any other transmission can not be greater than RXTresh/10

Background

The safe distance between two senders is 2RxR+RID

Perceptive Admission Control

Nodes determine the available bandwidth on their own No query flooding is needed

Change the CSR to 2RxR+RID Can determine accurate available

bandwidth without sending query messages A sender can detect the possible impact of

creating a new traffic

Determining the Available Bandwidth

MAC Layer Congestion Window Queue Length Number of Collision Delay Channel Busy Time

Transmitting Receiving Busy

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) V.S. PAC

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

Mobility

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

75% 75% ?

Mobility

Each source monitors the available bandwidth

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

Random back-off time

Simulation Result

Simulation Result

Simulation Result

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

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