doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 1 Proposal to Add Optional non n Radio Scans for 40 MHz Operation in 2.4 GHz Date: Authors:

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 2 Abstract From LB136 CID Comment The recommendation for the HT-STA not to transmit any 40 MHz mask PPDUs if it has knowledge of non devices operating in the area does nothing to ensure that n devices with such knowledge will not interfere with non n devices. In fact, it inadvertently creates a class of devices that knowingly interfere with non devices. If a device has the capability to detect the presence of other non devices, it should act upon such detection. The capability to detect non devices operating in the same area should be an option in the standard to address concerns relating to coexistence with non devices.

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 3 From LB136 CID Proposed Resolution Proposed changes: 1) In subclause , use the reserved bit B3 of the Extended Capabilities field for the HT AP or HT STA to declare its support for non radio scans. 2) In subclause , insert after line 12, page 223: Before an AP or IDO STA that is capable of detecting non radios (bit B3 of the Extended capabilities field is set to 1) starts a 20/40 MHz BSS, it shall perform overlapping BSS scans to search for non radios. 3) In subclause , insert after line 65, page 223, the following: An FC HT AP 2G4 that is capable of detecting non radios shall keep the value of 20/40 Operation Permitted to FALSE if a presence of non radio is detected. 4) Insert the following paragraph at the end of subclause , page 230, after line 13 An FC HT STA 2G4 that is associated with an FC HT AP 2G4 and is capable of performing non radio scans (bit B3 of the Extended Capability field is set to 1) shall perform at least one non radio scan every dot11BSSWidthTriggerScanInterval seconds., unless the FC HT STA 2G4 satisfies the conditions described in

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 4 Reasons for accepting the CID comment resolution as proposed  To remove the notion that the recommendation in the current IEEE802.11n Draft 7.0 creates a class of n devices that knowingly interfere with non devices  Results from new interference measurement tests (shown later in this submission) indicate that Bluetooth devices are severely affected for a significant period of time (up to 90 secs) after a 40 MHz BSS is started or the BSS switches from 20 MHz to 40 MHz in 2.4 GHz

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 5 Effects of 40 MHz operation in 2.4 GHz  Interference measurement tests so far indicated various degrees of interferences – See the following list of documents  vht-reponse-to-official-comments  n-additional-40-mhz-scanning-proposal  n mhz-11n-interference-on-bluetooth  n-11n-40-mhz-and-bt-coexistence-test-results vht-reponse-to-official-comment  ieee n-40-mhz-impact-on-bt-performance  It is observed that results of most measurement tests were taken when Bluetooth devices have already adapted to a new hopping sequence to avoid interfering channels

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 6 Interference Measurement Tests Focusing on BSS starting and switching to 40 MHz Severe interference to existing Bluetooth service was observed for a period of up to 90 secs after –BSS started a 40 MHz operation –BSS switched from 20 MHz to 40 MHz

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 7 Test Setup Agilent Spectrum Analyser ~10m 11n - AP 11n - STA Bluetooth dongle Bluetooth Headset ~1m

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 8 Test setup (ctn) 11n –Continuous Tx-Rx mode, Channel 5 –Bandwidth switched at noted time-stamp Bluetooth –Mustek Wireless Stereo Headset, MBT-A120 single tone sent from the laptop to headset through the dongle

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 9 Nominal Behaviour –Start (11n off) : 0s –11n-on : ~10s –11n-switch-BW : ~60s –11n-switch-BW : ~120s Top :  20MHz  40MHz Bottom :  40MHz  20MHz off40MHz20MHz40MHz off20MHz40MHz20MHz

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 10 Worst Case –Start (11n off) : 0s –11n-on : ~10s –11n-switch-BW : ~130s Top :  20MHz Bottom :  40MHz off40MHz20MHz off20MHz40MHz

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 11 AFH-Settling Times Nominal Startup TransitionTrial 1Trial 2Trial 3Average 40MHz->20MHz0s1ms ? 0s 20MHz->40MHz10s5s6s7s Worst Case Startup Trials are all randomly started and are unrelated across the rows/columns ? : a blip was heard 40MHz->20MHz0s

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 12 11n-40MHz Bluetooth 11n-20MHz 40MHz(adapt) 20MHz(adapt) Explanation (AFH)

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 13 Explanation (on a BW switch) 20MHz  40MHz 40MHz  20MHz (needs time to adapt) (has no extra interference) (lower available Bandwidth) (extra Bandwidth)

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 14 Conclusions Bluetooth AFH-adaptation Time  11n Switch-on Both 20MHz and 40MHz cause interferences to Bluetooth device  40MHz takes Bluetooth longer time to adapt  Worst case can result in more than 1 minute disruption  After AFH adapts, the effect of 11n is not perceived  11n Bandwidth-switch  40MHz  20MHz does not affect Bluetooth  20MHz  40MHz results in ~5-10s disruption

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 15 Proposal part 1 1)Add non n Radio Scan for 40 MHz Operation in 2.4 GHz as an option in the IEEE802.11n Draft 7.0 by countering the comment resolution as proposed by CID In subclause , use the reserved bit B3 of the Extended Capabilities field for the HT AP or HT STA to declare its support for non radio scans. In subclause , insert after line 37, page 223: Before an FC HT AP 2G4 or FC HT STA 2G4 that is capable of detecting non radios (bit B3 of the Extended capabilities field is set to 1) starts a 20/40 MHz BSS, it shall perform overlapping BSS scans to search for non radios. In subclause , insert after line 65, page 223, the following: An FC HT AP 2G4 that is capable of detecting non radios shall keep the value of 20/40 Operation Permitted to FALSE if a presence of non radio is detected. Insert the following paragraph at the end of subclause , page 230, after line 13 An FC HT STA 2G4 that is associated with an FC HT AP 2G4 and is capable of performing non radio scans (bit B3 of the Extended Capability field is set to 1) shall perform at least one non radio scan every dot11BSSWidthTriggerScanInterval seconds., unless the FC HT STA 2G4 satisfies the conditions described in

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 16 Proposal part 2 2) Adopt the “non radio scan” procedure described on slide 10 of the document n-additional-40-mhz-scanning-proposal (John R. Barr, Motorola Inc.) The “non radio scan” shall be able to detect presence of 1 MHz GFSK transmissions in channels centered on f=2402+k MHz for k=0..78 with a power level greater than –35 dBm that appear on at least 20 channels in a 10 mSec time period, and 5 MHz DSSS O-QPSK transmissions with a 2 MHz chip rate in channels centered on f= (k-11) MHz for k=11-26 with a power level greater than –38 dBm that appear on channels affected by the proposed 40 MHz channel in a 10 mSec time period. If either transmissions are detected “non radio scan” result is positive otherwise it is negative.

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 17 Final Conclusion Accepting this proposal will surely alleviate concerns on coexistence between 40 MHz capable n devices and others that share the 2.4 GHz band This will speed up approval of the n draft during the sponsor ballot.  Pay now to save later

doc.: IEEE /1238r4 Submission November 2008 Peter Loc & KiranSlide 18 Thank You Q&A