doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 1 Proposed Change to CCK-OFDM Signal Extension Mark Webster Steve Halford Intersil Corporation

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 2 Signal Extension For CCK-OFDM A 6 usec signal extension is added to CCK- OFDM to provide b SIFS compatibility Current g draft 1.1 specifies the signal extension as active on-the-air energy This presentation recommends specifying a paasive signal extension.

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 3 Signal Extension in g Draft 1.1

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 4 Proposed Change to Signal Extension Extend With No Signal

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 5 CCK-OFDM TXTIME Calculation TXTIME = PreambleLengthCCK + PLCPHeaderTimeCCK + PreambleLengthOFDM + PLCPSignalOFDM + 4 x Ceiling((PLCPServiceBits + 8 x (number-of-octets) + PadBits) / N DBPS ) + SignalExtension SignalExtension = 6 usecs Remains Unchanged

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 6 Disadvantages of Recommended Change None. –Current b implementations do not use a pure ED CCA mechanism. –An active signal extension only helps BSS where an ED mechanism is used. –The header length/field is necessary and sufficient

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 7 Advantages of Recommended Change The length field in the b header is necessary and sufficient to provide virtual CCA Matches the signal structure of the ER/OFDM. Maximizes reuse of existing a designs Enables faster Rx-to-Tx and Tx-to-Rx switching Saves battery power. BSS with only g stations, behave more like a

doc.: IEEE /102r0 Submission January 2002 M. Webster, et al IntersilSlide 8 Conclusion Make a motion: –Move to have the editor revise the g draft to specify that CCK-OFDM use a passive 6 usec signal extension.