1. Simulation Effort Required to Satisfy the 802.11n Comparison Criteria
March 2004
doc.: IEEE /307r0
March 2004
Simulation Effort Required to Satisfy the n Comparison Criteria
Bjorn A. Bjerke, John Ketchum,
and Irina Medvedev
Qualcomm, Inc.
Bjorn Bjerke et al., Qualcomm, Inc
Bjorn Bjerke et al. Qualcomm, Inc.

2. March 2004
Simulation Effort
Significant simulation effort required to satisfy the current version of the n Comparison Criteria
Two types of simulations:
PHY layer sims: typically implemented in C
System sims: typically implemented in NS2 or similar
Bjorn Bjerke et al., Qualcomm, Inc

3. CCs Involving Simulations
March 2004
doc.: IEEE /307r0
March 2004
CCs Involving Simulations
PHY sims:
CC59
CC67
CC67.1
CC67.2
System sims:
CC15
CC18
CC19
CC20
(CC24)
CC27
CC28
CC58
Bjorn Bjerke et al., Qualcomm, Inc
Bjorn Bjerke et al. Qualcomm, Inc.

4. March 2004
PHY Sims: Assumptions
NxN MIMO system  N*N possible system configurations
PER vs SNR evaluated for 10 SNR values
100 packet errors collected per point
CPU time per point: 1 hour
 CPU time per curve: 10 hours
Bjorn Bjerke et al., Qualcomm, Inc

5. PHY Sims: CPU Time Estimate
March 2004
PHY Sims: CPU Time Estimate
CC59 (PER vs SNR with fixed channel):
5 representative data rates
Example: N=4  16 system configurations
CPU time = 16*5*10 hours = 800 hours
CC67 (PER vs SNR with fading channels):
16 system configurations
3 channel models (B, D, F)
Channel D w/fluorescent lights and highest rate
CPU time = (16*5*3+16)*10 hours = 2560 hours
Bjorn Bjerke et al., Qualcomm, Inc

6. PHY Sims: CPU Time Estimate
March 2004
PHY Sims: CPU Time Estimate
CC67.1 (Rate vs SNR with fading channels):
16 system configurations
3 channel models (B, D, F)
Channel D w/fluorescent lights
CPU time = 16*4*10 hours = 640 hours
CC67.2 (PER for 2 SNR values with frequency offset):
Example: 5 representative freq. offset values
2 SNR values (1 hour each)
CPU time = 16*5*2 hours = 160 hours
Bjorn Bjerke et al., Qualcomm, Inc

7. PHY Sims: CPU Time Estimate
March 2004
PHY Sims: CPU Time Estimate
Total CPU time needed for PHY sims:
hours = 4160 hours
With 8 CPUs running continuously, this will take 4160/(24*8) days = 22 days
Assume 100% overhead  44 days
Bjorn Bjerke et al., Qualcomm, Inc

8. System Sims: Assumptions
March 2004
System Sims: Assumptions
Simulation Scenario 1 (baseline):
40 secs. of simulated time to reach steady state; < 1 hour of CPU time to simulate
Assume CPU time goes as the square of the number of STAs
Bjorn Bjerke et al., Qualcomm, Inc

9. System Sims: CPU Time Estimate
March 2004
System Sims: CPU Time Estimate
CC15:
SS17: 1 AP, 1 STA, 1 channel model; < 1 hour
SS18: 1 AP, 1 STA, 1 channel model; < 1 hour
SS19: 1 AP, 2 STA, 1 channel model; < 1 hour
CCs 18, 19, 20, 24
SS1:  1 AP, 11 STA --  1 hour
SS4:  1 AP, 30 STA -- 7 hours
SS6:  1 AP, 52 STA  hours
SS9:  1 AP, 6 STA --  1 hour
SS11: 2 AP, 12 STA -- 2 hours
Bjorn Bjerke et al., Qualcomm, Inc

10. System Sims: CPU Time Estimate
March 2004
doc.: IEEE /307r0
March 2004
System Sims: CPU Time Estimate
CCs 27, 28, 58
Need to run SS16 for each of the two channel models, B and D.
SS16: 1 AP, 1 STA, repeated for various locations of the STA   
Total: 4 hours
Total CPU time for system sims: < 40 hours 
Add 100% overhead: < 80 hours
Bjorn Bjerke et al., Qualcomm, Inc
Bjorn Bjerke et al. Qualcomm, Inc.

11. The Simulation Effort May Be Reduced Without Compromising Quality
March 2004
The Simulation Effort May Be Reduced Without Compromising Quality
PHY sims represent the majority share of the effort  focus on PHY sims:
Limit the number of required system configurations to a set of 5 representative, e.g., 1xN, Nx1, N1xN1, N1xN2, and N2xN2
Let proposer choose between CC67 and CC67.1, i.e., make CC67 mandatory for fixed rate systems, and make CC67.1 mandatory for rate-adaptive systems
Total CPU time required drops to 1100 hours and 500 hours, respectively (or 1300 hours if all versions of CC67 are mandatory)
Bjorn Bjerke et al., Qualcomm, Inc