802.11 PCF Model Progress Update Nov 2000 Month 2000 doc.: IEEE 802.11-00/xxx November 2000 802.11 PCF Model Progress Update Nov 2000 Author: Matthew Sherman AT&T Labs - Research 180 Park Avenue Florham Park, NJ 07932 973-236-6791 mjsherman@att.com Date: November 8, 2000 Matthew Sherman, AT&T Labs - Research John Doe, His Company

Introduction / Background Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Introduction / Background Prior descriptions in: IEEE 802.11-00/264r1 IEEE 802.11-00/318r1 PCF model developed by AT&T Labs Validation still required Jumping off point for MAC enhancements Currently available under NDA from AT&T May become part of OPNET Standard Library Eventual contributed model with enhancements No NDA for contributed model Matthew Sherman, AT&T Labs - Research John Doe, His Company

Mods Since Sept ‘00 Meeting Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Mods Since Sept ‘00 Meeting Implemented more_data bit in frame format PCF use only Streamlined frame formats New packet formats called: Wlan_mac_pcf Wlan_control_pcf Added all possible fields that might be needed for data / management frames Reduced Control Frame fields since some irrelevant Fix to beacon header size Off by 6 bytes Receiver busy / SIFS fix Receiver busy now ignored during SIFS Matthew Sherman, AT&T Labs - Research John Doe, His Company

Mods Since Sept ‘00 Meeting (Cont.) Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Mods Since Sept ‘00 Meeting (Cont.) Fixed frame timeout for PCF side traffic AP was not waiting long enough for traffic EIFS fix Was still being set in NAV for some cases PCF Duration field fixes Was setting to 0 rather than 32768 AP NAV reset at start of CFP May reconsider later Option to reset NAV for CF_END for all BSSs or only own BSS NS Compatible trace capability Update to October models capability Matthew Sherman, AT&T Labs - Research John Doe, His Company

Mods Since Sept ‘00 Meeting (Cont.) Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Mods Since Sept ‘00 Meeting (Cont.) Assorted Retry fixes Wrong frame type, duration filed, trace info, etc. Added support for multi-source model “Ghost Packet” and other receiver fixes TBTT overrun fix Max packet size fix Broadcast packet CW reset fix Fragment train before Beacon Fix Various other minor fixes PCF poll flag fixes sometimes PCF active flag was set by mistake Matthew Sherman, AT&T Labs - Research John Doe, His Company

Current Scenario Simulated Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Current Scenario Simulated Based on most current “Model 3 Scenario” Modified Video Conference packet generation Packets were too large Added bulk traffic stream 10 sec into simulation Load system beyond channel capacity Addresses assigned to favor higher priority traffic Addresses used as AID by poll scheduler Will update scenario to final “Model 3” once completed MPEG sources Finalize Video Conference and data streams Matthew Sherman, AT&T Labs - Research John Doe, His Company

OPNET Scenario Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Matthew Sherman, AT&T Labs - Research John Doe, His Company

MAC Parameters Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Matthew Sherman, AT&T Labs - Research John Doe, His Company

Traffic Sources Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Source Address Start Time (Sec) ON State Time OFF State Time Interarrival Time Packet Size (Bytes) Stop Time (Sec) Destination Address Type of Service Stream ID 0.02 3600. 0. Uniform (0.08333,0.25) 815 Never 3 5 0.012 0.088 0.001 1464 4 6 10.02 Poisson (0.005) 2300 1 92 2 40 7 0.003012 1504 8 Lognormal (0.01136, 0.00001) 64 9 Matthew Sherman, AT&T Labs - Research John Doe, His Company

Global Stats PCF DCF Month 2000 doc.: IEEE 802.11-00/xxx November 2000 100 values / bin Collection mode - Total / time. PCF DCF Matthew Sherman, AT&T Labs - Research John Doe, His Company

Global Stats 100 values / bin in simulations Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Global Stats 100 values / bin in simulations Groups of values (100) are processed at a time to generate displayed statistics Global Stats are aggregate values across all streams Delay is time from when packet queued in MAC until final Ack indicating successful delivery Load is traffic presented to MAC from upper layers Media Access Delay is time from packet queued in MAC until first access of medium Throughput is traffic forwarded to upper layers Packets dropped self explanatory 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

Global Stats - Performance Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Global Stats - Performance PCF outperforming DCF from start Some packet drops on DCF, none on PCF PCF delays lower See effects of Bulk data kick in at 10 sec Large number of packet drops Delays start getting really bad Throughput on PCF increases slightly when Bulk data starts Throughput on DCF seems to slightly decrease More retrys / backoffs 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

Dropped Packets PCF DCF Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Dropped Packets Voice Voice Voice Audio Ack Bulk Data Audio Video Conf. 100 values / bin Collection mode - Total / time. Video Conf. MPEG Data Ack PCF DCF Matthew Sherman, AT&T Labs - Research John Doe, His Company

Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Dropped Packets Clearly see that DCF is dropping MPEG traffic almost from the start Probably running out of buffer room When Bulk data starts, DCF drops even more MPEG and bulk video No other data affected (in first 20 sec) Video conferencing is affected in longer simulations (>30 sec) Seems to be function of overall rate (buffer room) PCF drops bulk data but nothing else Only drops lowest priority stream Maintains all QoS streams 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

Retransmission Attempts Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Retransmission Attempts 100 values / bin Collection mode - Total / time. PCF DCF Matthew Sherman, AT&T Labs - Research John Doe, His Company

Retransmission Attempts Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Retransmission Attempts Substantial retransmission activity for DCF Bulk Data has no obvious effects on retry Medium already saturated Retransmissions consume capacity No Retransmissions required in PCF Obvious and Expected Efficiency advantage over DCF 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

Packet Delays PCF DCF Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Packet Delays Voice Voice Voice Audio Ack Bulk Data Audio Video Conf. Source MAC entry till Successful delivery (but includes Ack) Collection Mode - Sample mean - Average does not show peak delay. Need to investigate Gaps in results. Video Conf. MPEG Data Ack PCF DCF Matthew Sherman, AT&T Labs - Research John Doe, His Company

Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Packet Delays PCF packet delays very stable and well bounded on all streams but bulk data Can maintain QoS Especially true for voice Some dependence on polling order DCF shows substantially greater delay variation in all streams MPEG already degraded Video Conferencing and Audio hit hard by bulk data QoS is not maintained Streams sharing AP with Bulk data hit hardest 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

DCF Trace - Synchronized Data Month 2000 doc.: IEEE 802.11-00/xxx November 2000 DCF Trace - Synchronized Data s -t 0.078352 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms 6 -Mt WlanC_Ack x -t 0.078464 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms 6 -Mt WlanC_Ack r -t 0.078465 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack r -t 0.078465 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack r -t 0.078465 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack r -t 0.078465 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack r -t 0.078465 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack r -t 0.078465 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms -2 -Mt WlanC_Ack s -t 0.080000 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md -1 -Ms 0 -Mt WlanC_Beac s -t 0.080000 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 2 -Ms 1 -Mt WlanC_Data s -t 0.080000 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data s -t 0.080000 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 3 -Mt WlanC_Data x -t 0.080087 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 2 -Ms 1 -Mt WlanC_Data x -t 0.080087 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data x -t 0.080087 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 3 -Mt WlanC_Data d -t 0.080087 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms 1 -Mt WlanC_Data d -t 0.080087 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 0 -Ms 3 -Mt WlanC_Data d -t 0.080087 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 1 -Ms 2 -Mt WlanC_Data d -t 0.080087 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 0 -Ms 3 -Mt WlanC_Data d -t 0.080088 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 0 -Ms 3 -Mt WlanC_Data x -t 0.080504 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 1 -Ms 2 -Mt WlanC_Beac d -t 0.080504 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md -1 -Ms 0 -Mt WlanC_Beac d -t 0.080504 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md -1 -Ms 0 -Mt WlanC_Beac s -t 0.081074 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data x -t 0.081161 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data r -t 0.081162 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 1 -Ms 2 -Mt WlanC_Data s -t 0.081172 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms 1 -Mt WlanC_Ack x -t 0.081284 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms 1 -Mt WlanC_Ack r -t 0.081284 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack r -t 0.081284 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack r -t 0.081284 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack r -t 0.081284 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack r -t 0.081284 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack r -t 0.081284 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 2 -Ms -2 -Mt WlanC_Ack Show Beacon collision Effects of data synchronization / post backoff when Medium Idle Matthew Sherman, AT&T Labs - Research John Doe, His Company

Key Trace features NS compatible First letter is event type Month 2000 doc.: IEEE 802.11-00/xxx November 2000 Key Trace features NS compatible First letter is event type T: packet Tx start X: packet Tx end R: packet received D: packet drop -t indicates simulation time (rounded to microsec) -Hs is observing (reporting) station address -Na is Duration field -Md is packet destination -Ms is packet source Frame type at end of line 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

DCF Trace - Synchronized Data Month 2000 doc.: IEEE 802.11-00/xxx November 2000 DCF Trace - Synchronized Data Multi-packet collision is common in simulations Prior to beacon all STA have completed post-backoff Data frame generated in sources at same time 3 voice calls have identical parameters Also synchronized with Beacon Collisions could be avoided by phasing sources to discourage simultaneous triggering What about network synchronization Can devices in real network become synchronized so that this becomes a common problem? 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company

DCF Trace - Delayed Beacon Month 2000 doc.: IEEE 802.11-00/xxx November 2000 DCF Trace - Delayed Beacon s -t 0.118858 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 4 -Ms 0 -Mt WlanC_Data x -t 0.119943 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 4 -Ms 0 -Mt WlanC_Data s -t 0.119954 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 0 -Ms 4 -Mt WlanC_Ack x -t 0.120066 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 0 -Ms 4 -Mt WlanC_Ack s -t 0.120337 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 6 -Ms 5 -Mt WlanC_Data x -t 0.121451 -Hs 5 -Hd -2 -Ni 5 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 6 -Ms 5 -Mt WlanC_Data s -t 0.121461 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms 6 -Mt WlanC_Ack x -t 0.121573 -Hs 6 -Hd -2 -Ni 6 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 5 -Ms 6 -Mt WlanC_Ack s -t 0.121684 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 3 -Mt WlanC_Data x -t 0.121771 -Hs 3 -Hd -2 -Ni 3 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 3 -Mt WlanC_Data s -t 0.121782 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 3 -Ms 0 -Mt WlanC_Ack x -t 0.121894 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 3 -Ms 0 -Mt WlanC_Ack s -t 0.121965 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 2 -Ms 1 -Mt WlanC_Data x -t 0.122052 -Hs 1 -Hd -2 -Ni 1 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 2 -Ms 1 -Mt WlanC_Data s -t 0.122062 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 1 -Ms 2 -Mt WlanC_Ack x -t 0.122174 -Hs 2 -Hd -2 -Ni 2 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 1 -Ms 2 -Mt WlanC_Ack s -t 0.122265 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 4 -Mt WlanC_Data x -t 0.123350 -Hs 4 -Hd -2 -Ni 4 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 123 -Md 0 -Ms 4 -Mt WlanC_Data s -t 0.123360 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 4 -Ms 0 -Mt WlanC_Ack x -t 0.123472 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md 4 -Ms 0 -Mt WlanC_Ack s -t 0.123623 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md -1 -Ms 0 -Mt WlanC_Beac x -t 0.124127 -Hs 0 -Hd -2 -Ni 0 -Nx -53.26 -Ny 24.91 -Nz 100.00 -Ne -1.000000 -Nl MAC -Nw --- -Na 0 -Md -1 -Ms 0 -Mt WlanC_Beac Show Beacon collision Effects of data synchronization / post backoff when Medium Idle Matthew Sherman, AT&T Labs - Research John Doe, His Company

DCF Trace - Delayed Beacon Month 2000 doc.: IEEE 802.11-00/xxx November 2000 DCF Trace - Delayed Beacon For DCF, Beacon is required to follow DCF rules Must back off and defer like any other frame In simulations backoff and deference can cause Beacon to be delayed beyond TBTT by several frames In this case delayed 9 frames Delayed roughly 3.6 milliseconds Nothing wrong, but interesting to observe Demonstrates utility of trace 100 values / bin Collection mode - Total / time. Matthew Sherman, AT&T Labs - Research John Doe, His Company