EDCF / EPCF Comparisons

1. EDCF / EPCF Comparisons Matthew Sherman AT&T Labs - Research 180 Park Avenue Florham Park, NJ 07932 973-236-6925 mjsherman@att.com Author: Date: September 8, 2002 Matthew Sherman, AT&T Labs - Research

2. Purpose of Document • Quick comparison of EDCF with EPCF • Mostly for new comers Matthew Sherman, AT&T Labs - Research

3. Background • Few comparisons of E-DCF and HCF • AT&T has simulated both E-DCF and E-PCF • E-DCF simulations – eg. 01/004 and 01/019 • E-PCF simulations – eg. 02/303, 02/304, 02/305 • E-PCF just like HCF except CF access only during CFP • HCF should perform even better since less constrained • Easier for AT&T to simulate E-PCF • AT&T’s original interest before HCF created • AT&T never provided head to head comparison • First such comparisons by AT&T Matthew Sherman, AT&T Labs - Research

4. Simulation Scenario • Same parameters as in 01/004 • 01/004 did not use PHY • Ran CC/RR/EDCF code • with 802.11b PHY • with 802.11b access parameters but no modeling of PHY overhead • Some output statistics different as well Matthew Sherman, AT&T Labs - Research

5. Plots Collected • Matched plots in 01/004 as closely as possible • Statistics not identical to CC/RR/EDCF model • Stuck with Throughput (Goodput), Media Access Delay, and Data Dropped • “Streams” here correlate to “Calls” in 01/004 • Streams are renumbered (relative to Calls) to correlate with when streams start Matthew Sherman, AT&T Labs - Research

6. E-PCF sims of E-DCF Scenarios • Configured code to run E-DCF Scenarios using E-PCF • 20 msec Beacon Period (18 msec CFP) • E-DCF simulations used 100 msec Beacon Period • Standing Poll (no CC/RR) • Addresses arranged according to priority • Priority based scheduler • no attempt at fairness Matthew Sherman, AT&T Labs - Research

7. 5.0 Mbps MEDIUM 2.5 Mbps LOW 5.0 Mbps TOP 2.5 Mbps LOW Traffic loading • Same EDCF parameters for classes as 00/004 0 30 90 150 Time (sec) Matthew Sherman, AT&T Labs - Research

8. E-PCF simulationsof E-DCF scenarios Matthew Sherman, AT&T Labs - Research

9. Throughput E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

10. Media Access Delay E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

11. Media Access Delay (Zoomed) E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

12. Data Dropped E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

13. Data Analysis – E-PCF • Dramatic performance differences between E-DCF and E-PCF • High priority delays / drops much better for E-PCF • Difference between acceptable / unacceptable Voice • E-DCF much more sensitive to overload • E-PCF drops less data in general • No “fairness” between classes in E-PCF • Could be fixed with more advanced scheduler • HCF would be better still Matthew Sherman, AT&T Labs - Research

14. E-PCF simulationsof E-DCF scenarios(No PHY) Matthew Sherman, AT&T Labs - Research

15. Throughput E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

16. Media Access Delay E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

17. Media Access Delay (Zoomed) E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

18. Data Dropped E-DCF E-PCF Matthew Sherman, AT&T Labs - Research

19. Data Analysis – E-PCF (no PHY) • While the E-DCF performance degradation is not as sever as with the PHY it is still substantial • All the comments identified for the simulations with a PHY would still apply Matthew Sherman, AT&T Labs - Research