1. Simulations of Probes, Authentication, Association and Keys
November 2012
doc.: IEEE /1368r0
November 2012
Simulations of Probes, Authentication, Association and Keys
Date:
Authors:
Graham Smith, DSP Group
Graham Smith, DSP Group

2. November 2012
doc.: IEEE /1368r0
November 2012
Abstract
A simulation has been written for up to 100 STAs that come on air at various times using different Access Categories:
All together
Random
Various distributions
The outputs include:
Overall time
Delays and Response time
Graham Smith, DSP Group
Graham Smith, DSP Group

3. November 2012
The problem is that as the number of STAs increases, the contention increases. If the number of back off slots
Is comparable to the number of STAs, then it becomes more unlikely to find a free slot.
As STAs get serviced, the probability gets better, hence the calculation is complicated.
For example, if using AC_VO with CWmin = 3 (4 slots), then if >50 STAs, would need to back off at least 3 times to
Get to 32 slots distribution.
Graham Smith, DSP Group

4. Basic Times November 2012 Probes Rqst/Resp 46 192 Probe duration + ACK
148
340 VO BE
Total, us
587
677
395
485 VO BE
Auth Request
181.5
289.5
6Mbps
Auth Response
172.5
280.5
Assoc Request
279.5
333.5
Assoc Response
278.5
332.5
Key 1
318.5
372.5
Key 2
327.5
381.5
Key 3
366.5
420.5
Key 4
299.5
344.5
Sum
2224
2755 us
Graham Smith, DSP Group

5. Distributions November 2012
Split total time into 20 slots, e.g. For 100 STAs over 1 second, time slot is 50ms.
Note: Random distribution changes every time
Graham Smith, DSP Group

6. Active Probes – 6Mbps Delay time of Response after Request
November 2012
Active Probes – 6Mbps Delay time of Response after Request
100 STAs
AC_BE
Distributed over 1 sec
Random
Poisson
Rayleigh
Normal
Linear
Simultaneous
Average, ms
0.45 35
% under 5ms
100 2
time to complete 85ms
STAs BE, AP VO
0.38
0.65
STAs and AP VO
1.1 98
time to complete 110ms
Graham Smith, DSP Group

7. Active Probes – 6Mbps Delay time of Response after Request
November 2012
Active Probes – 6Mbps Delay time of Response after Request
100 STAs
AC_BE
Distributed over 100msec
Random
Poisson
Rayleigh
Normal
Linear
Simultaneous
Average, ms
0.7
4.5
1.7
2.5
0.55 35
% under 5ms
100 55 98 97 2
time to complete 85ms
STAs BE, AP VO
0.4
0.47
0.45
0.65
STAs and AP VO
1.1
0.9 1
time to complete 110ms
Best condition is STAs using AC_BE and AP using AC_VO
Graham Smith, DSP Group

8. Probes, Authentication, Association, Keys
November 2012
Probes, Authentication, Association, Keys
Traffic
STA0
SIFS 16
AIFSN 2
Dwmin 3
Dwmax 7
SlotTime 9
Probe Rqst, Bytes 46
Data Rate 6
ACK
Pkt + ACK
148
Probe Resp Bytes
192
Pkt + Ack
340
Auth R&R Bytes 34
132
Assoc Rqst Bytes
121 24
108
Assoc Resp Bytes
128
Key 1, 2 Bytes
159
120
Key 3 Bytes
193
Key 4 Bytes
137
112
Traffic
STA0
SIFS 16
AIFSN 2
Dwmin 3
Dwmax 7
SlotTime 9
Probe Rqst, Bytes 46
Data Rate 6
ACK
Pkt + ACK
148
Probe Resp Bytes
192
Pkt + Ack
340
Up to 100 STAs
Auth R&R Bytes 34
Data Rate 6
ACK
Pkt + ACK
132
Assoc Rqst Bytes
121 24
Pkt + Ack
108
Assoc Resp Bytes
128
Key 1, 2 Bytes
159
Data Rate 24
ACK
Pkt + Ack
120
Key 3 Bytes
193
132
Key 4 Bytes
137
112
can set the AC, respective data rates, respective packet sizes .
Graham Smith, DSP Group

9. AC_BE with 20Mbps AC_VO traffic @ 36Mbps
November 2012
AC_BE with 20Mbps AC_VO 36Mbps
Distribution
Random
1 second
% under 100ms
100 %
Delays
4 to 45 ms
Poisson
11 to 50
Rayleigh
5 to 40
Normal 93
62 to 100
Linear
4 to 24
Simultaneous
250 to 290
Complete
350 to 370
Looks pretty good!
Normal Distribution is toughest
100 STAs together completes in ~360ms
Graham Smith, DSP Group

10. November 2012
Thoughts
Based on the results it seems to me that the existing protocol is capable of meeting the requirements
Does not account for processing time within the Devices
Graham Smith, DSP Group

11. Demo The simulation will now be shown.
November 2012
Demo
The simulation will now be shown.
Note that the variations/settings are:
AC settings – DWmin, DW max, AIFSN, SIFS, Slot time
Packet sizes
PHY Rates
Other traffic
The problem is that I am unsure where to go next and would welcome thoughts on what to measure
Would like to apply this to new proposals
Graham Smith, DSP Group