1. doc.: IEEE 802.11-08/1101r0 Submission September 2008 John R. Barr, Motorola, Inc.Slide 1 Additional 40 MHz Scanning Proposal Date: 2008-09-09 Authors:

2. doc.: IEEE 802.11-08/1101r0 Submission September 2008 John R. Barr, Motorola, Inc.Slide 2 Abstract Due to the number of negative comments that have been cast in the recent letter ballot regarding use of 40 MHz channels in 2.4 GHz spectrum, it is proposed to add scanning requirements to clause 11.14 for FC HT AP 19 and FC HT ATA 19 devices to detect presence of non-802.11 radios operating in 2.4 GHz spectrum and set the Forty MHz Intolerant field to 1 in transmitted HT Capabilities elements if detection is positive. This should be sufficient to resolve all of the latest negative comments (9304, 9044, 9041, 9009, and unresolved comments from earlier ballots).

3. doc.: IEEE 802.11-08/1101r0 Submission September 2008 John R. Barr, Motorola, Inc.Slide 3 Coexistence with other IEEE 802 Standards Current draft 802.11n provides substantial coexistence language for legacy IEEE 802.11 devices via mandatory scanning prior to enabling operation of 40 MHz channels. 40MHzIntolerant bit is used to inform other devices in BSS that operation of 40 MHz channels is not allowed. Adding mandatory scanning for non-IEEE 802.11 devices operating in 2.4 GHz should satisfy negative letter ballot comments and improve the draft.

4. doc.: IEEE 802.11-08/1101r0 Submission September 2008 John R. Barr, Motorola, Inc.Slide 4 Current Coexistence Language Normative: –11.14.12: “ An FC HT AP 19 that detects either of the BSS channel width trigger events TE-B or TE-C or that determines that the value of its variable 20/40 Operation Permitted has changed from TRUE to FALSE shall set the Secondary Channel Offset field to SCN in transmitted HT Operation elements beginning at the next DTIM or next TBTT if no DTIMs are transmitted to indicate that no secondary channel is present (i.e., that the BSS operating width is 20 MHz). ” Informative: –T.5.2: “ Before starting a 20/40 MHz BSS, an 40 MHz capable HT AP is required by the rules defined in 11.14.5 to examine the channels of the current regulatory domain to determine whether the operation of a 20/40 MHz BSS might unfairly interfere with the operation of existing 20 MHz BSSs. The AP (or some of its associated HT STAs) is required to scan all of the channels of the current regulatory domain in order to ascertain the operating channels of any existing 20 MHz BSSs and 20/40 MHz BSSs. ”

5. doc.: IEEE 802.11-08/1101r0 Submission Current Coexistence Language (2) Informative: –T.5.2: “An additional constraint on establishing a 20/40 MHz BSS includes the allowance for any 802.11 device to explicitly prohibit the operation of the 20/40 BSS mode due to other considerations. For example, if an 802.15.1 WPAN device is operating in the area, that device is likely to be unable to communicate successfully with a paired receiver if the number of available 802.15.1 WPAN channels falls below a given threshold. Operation of a 20/40 MHz BSS in the 2.4 GHz band can contribute to the reduction of the number of available 802.15.1 WPAN channels, possibly pushing the available channels below that threshold.” September 2008 John R. Barr, Motorola, Inc.Slide 5

6. doc.: IEEE 802.11-08/1101r0 Submission Over the Air Measurements Confirm that operation of 40 MHz 802.11n Channels Interferes with typical 802.15.1 use cases. Number of retransmissions for A2DP increase by a factor of 15. Number of error free packets reduced by a factor of 2. Results in numerous stereo audio drop outs. Adaptive Frequency Hopping (AFH) enabled, but typical detection algorithms can’t handle 100% larger channels and intermittent use of that channel. September 2008 John R. Barr, Motorola, Inc.Slide 6

7. doc.: IEEE 802.11-08/1101r0 Submission Current Negative Comments Suggest Resolution: –Clause 20.3.25, line 22, replace "When using 40 MHz channels, it can operate in the channels defined in 20.3.15.1 and 20.3.15.2." to "When using 40 MHz channels, it can operate in the channels defined in 20.3.15.2." Rationale: –Due to the large number of devices based on IEEE Std 802.15.1™- 2005 (e.g., > TWO Billion Bluetooth wireless devices), the probability of sharing the spectrum with 802.11n devices will be high. September 2008 John R. Barr, Motorola, Inc.Slide 7

8. doc.: IEEE 802.11-08/1101r0 Submission Alternative Proposal Add clause to 11.14 20/40 MHz BSS Operation: –FC HT AP 19 and FC HT STA 19 devices shall perform a “non- 802.11 radio scan” (TBD) prior to establishing/joining a 20/40 MHz BSS and at least once per dot11BSSWidthTriggerScanInterval seconds during operation of a 20/40 MHz BSS. A positive scan result shall cause the 20/40 Operation Permitted local variable to be set to FALSE in an FC HT AP 19 and the dot11FortyMHzIntolerant MIB attribute set to TRUE. A negative scan result shall have the opposite effect. –Note that the exact integration of scan event results may be best integrated into clause 11.14.12. September 2008 John R. Barr, Motorola, Inc.Slide 8

9. doc.: IEEE 802.11-08/1101r0 Submission “non-802.11 radio scan” IEEE 802.22 has investigated radio feature detection methods. IEEE 802.15.1 (Bluetooth) wireless devices utilize a low cost scanning mechanism to detect presence of frequency hopping signals with pseudo-random hopping sequences. IEEE 802.15.4 (Zigbee) wireless devices use energy detection and an active scan to detect beacons of 802.15.4 devices. A combination of these methods can be used to define the “non- 802.11 radio scan” algorithm and detection limits. –Similar to DFS algorithm used for radar detection –Detection limits based on expected signal level of non-802.11 radio within range of likely interference by 40 MHz 802.11n transmissions (e.g., 3m). –Confirmation of algorithm and detection limits from at least Bluetooth SIG and Zigbee Alliance. September 2008 John R. Barr, Motorola, Inc.Slide 9

10. doc.: IEEE 802.11-08/1101r0 Submission Process TGn develops language for insertion of “non-802.11 radio scan” into clause 11.14 and other clauses as necessary. Bluetooth SIG and Zigbee Alliance provide details on detection of their radios and recommended detection limits. TGn integrates detection methods into single algorithm for inclusion in 802.11n draft. Sponsor Ballot... September 2008 John R. Barr, Motorola, Inc.Slide 10

11. doc.: IEEE 802.11-08/1101r0 Submission September 2008 John R. Barr, Motorola, Inc.Slide 11 References https://mentor.ieee.org/802.11/file/08/11-08-0962-01- 000n-tgn-lb134-coex-comments.xlshttps://mentor.ieee.org/802.11/file/08/11-08-0962-01- 000n-tgn-lb134-coex-comments.xls https://mentor.ieee.org/802.11/file/08/11-08-0779-01- 000n-coex-40-mhz-comments.dochttps://mentor.ieee.org/802.11/file/08/11-08-0779-01- 000n-coex-40-mhz-comments.doc https://mentor.ieee.org/802.11/file/08/11-08-0992-01- 000n-20-40-mhz-11n-interference-on-bluetooth.ppthttps://mentor.ieee.org/802.11/file/08/11-08-0992-01- 000n-20-40-mhz-11n-interference-on-bluetooth.ppt