January 2012
doc.: IEEE 802.11-12/0112r2
Supporting Authentication/Association for Large
Number of Stations
Date: 2012-03-12
Authors:
Name
Affiliations
Address
Phone
email
Haiguang Wang
I2R
+65 6408 2256
[email protected]
Jaya Shankar
I2R
1 Fusionopolis Way, #21-01,
Connexis South Tower, Singapore
138632
1 Fusionopolis Way, #21-01,
Connexis South Tower, Singapore
138632
+65 6408 2239
[email protected]
Shoukang Zheng
Hoang Anh Tuan
I2R
I2R
Yeow Wai Leong I2R
Joseph Teo Chee
Ming
Zander Lei
Submission
I2R
I2R
Slide 1
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Abstract
In this contribution, we present the performance of
current Authentication/Association protocols for 802.11
networks with large number of nodes. We found that it
is necessary to limit the number of stations that can
perform the authentication/association simultaneously.
Submission
Slide 2
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Motivation
• IEEE 802.11ah is required to support up to 6000 stations by
a single AP [1]. It is necessary to examine performance of
existing standard in supporting large number of nodes,
including authentication/association.
Submission
Slide 3
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Usage Scenarios
• In smart grid application, when AP or stations
experience power outage, the stations may try to
authenticate/associate with AP simultaneously after
recovery. The AP is required to handle a sudden burst
of authentication/association requests from a few
thousands stations within a short period.
Submission
Slide 4
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Authentication/Association Procedure
Submission
Slide 5
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Simulation Parameters
• Simulator
– Qualnet network simulator
• Simulation parameters
•
• DCF mode with 1 MHz bandwidth as specified by 802.11ah frame work
• With implemented power saving protocols.
• PHY modulation: MCS0-REP2
• Transmission range: 1 km
Basic parameters
Parameter
Value
Parameter
Value
Data Rate
150 Kbps
Backoff Win
15 - 1023
Number of Nodes
50- 3000
Maximum Short Retry
7
DIFS
250 us
Maximum long Retry
4
SIFS
160 us
Time slot
45 us
Beacon Interval
200 milliseconds
DTIM Period
25 (5 seconds)
PS Mode Listen Interval
25 (5 seconds)
Submission
Slide 6
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Topology
Submission
Slide 7
Haiguang Wang et. al, I2R, Singapore
doc.: IEEE 802.11-12/0112r2
Performance Results for Authentication/Association of Stations
within 200 Seconds Limit
Submission
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Suggested Solution: Using MAC Address
• Limit the number of stations that can authenticate/associate with
AP at the same time.
– Make use of the last byte of station’s MAC address to limit the number of
stations.
– AP broadcast a value V in the beacon.
– Stations with last byte of MAC address less than V are allowed to send
authentication request.
– AP can adjust the value of V to control the number of stations performing
authentication/association process.
• Alternative solution to solve unfairness due to MAC address
assignment;
– AP broadcast two values, V1 and V2, to the stations
– Stations with last byte of its MAC address falls in [V1, V2] are allowed to
send authentication request.
– AP adjust the value of V1 and V2 to control the number of stations
performing authentication/association process.
Submission
Slide 9
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Performance Results Using Proposed Method
Submission
Slide 10
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Suggested Solution: Using Random
Numbers
• Limit the number of stations that can authenticate/associate with
AP at the same time.
– Make use of random number to limit the number of stations.
– AP broadcast a value V in the beacon.
– Stations with random number less than V are allowed to send
authentication request.
– AP can adjust the value of V to control the number of stations performing
authentication/association process.
Submission
Slide 11
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Performance Results: Using Random Numbers
Submission
Slide 12
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Conclusions
• Simulation results show that, it is necessary to control the number of
stations performing authentication/association at the same time to
improve the performance in scenario with large number of stations.
Submission
Slide 13
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
References
• [1] Chao-Chun Wang, “Supporting Large Number of
STAs in 802.11ah”, IEEE 802.11-11/1019, July 2011.
• [2] Siyang Liu, Luo Zhengdong, Daning Gong, “DCF
Enhancements for Large Number of STAs”, IEEE
802.11-11/1255, Sep 2011.
Submission
Slide 14
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Straw Poll (1)
• Do you agree that AP should limit the number of
stations to be authenticated/associated at the same
time?
• Y:
• N:
• A:
Submission
Slide 15
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Straw Poll (2)
• Do you agree to use MAC address to limit the number
of stations to be authenticated/associated at the same
time?
• Y:
• N:
• A:
Submission
Slide 16
Haiguang Wang et. al, I2R, Singapore
January 2012
doc.: IEEE 802.11-12/0112r2
Straw Poll (3)
• Do you agree to use random number to limit the
number of stations to be authenticated/associated at the
same time?
• Y:
• N:
• A:
Submission
Slide 17
Haiguang Wang et. al, I2R, Singapore