Embed Size (px)
Citation preview
November 2008
Peter Loc & Kiran
Slide 1
doc.: IEEE 802.11-08/1238r4
Submission
Proposal to Add Optional non 802.11n Radio Scans for 40 MHz Operation in 2.4 GHz
Date: 2008-10-21Authors:
Name Affiliations Address Phone email
Peter Loc Ralink Technology
20833 Stevens Creek Blvd, Suite 200., Cupertino CA 95014
408 807-0868 [email protected]
Kiran Ralink Technology
20833 Stevens Creek Blvd, Suite 200., Cupertino CA 95014
408 725-8070 [email protected]
November 2008
Peter Loc & Kiran
Slide 2
doc.: IEEE 802.11-08/1238r4
Submission Slide 2
AbstractFrom LB136 CID 10025 Comment
The recommendation for the HT-STA not to transmit any 40 MHz mask PPDUs if it has knowledge of non-802.11 devices operating in the area does nothing to ensure that 802.11n devices with such knowledge will not interfere with non-802.11n devices. In fact, it inadvertently creates a class of 802.11 devices that knowingly interfere with non-802.11 devices. If a device has the capability to detect the presence of other non-802.11 devices, it should act upon such detection. The capability to detect non-802.11 devices operating in the same area should be an option in the standard to address concerns relating to coexistence with non 802.11 devices.
November 2008
Peter Loc & Kiran
Slide 3
doc.: IEEE 802.11-08/1238r4
Submission Slide 3
From LB136 CID 10025 Proposed Resolution
Proposed changes:• 1) In subclause 7.3.2.57.5, use the reserved bit B3 of the Extended Capabilities field
for the HT AP or HT STA to declare its support for non-802.11 radio scans.• 2) In subclause 11.14.3.2, insert after line 12 , page 223:• Before an AP or IDO STA that is capable of detecting non-802.11 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-802.11 radios.
• 3) In subclause 11.14.3.2, insert after line 65 , page 223, the following:• An FC HT AP 2G4 that is capable of detecting non-802.11 radios shall keep the
value of 20/40 Operation Permitted to FALSE if a presence of non-802.11 radio is detected.
• 4) Insert the following paragraph at the end of subclause 11.14.5, 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-802.11 radio scans (bit B3 of the Extended Capability field is set to 1) shall perform at least one non 802.11 radio scan every dot11BSSWidthTriggerScanInterval seconds., unless the FC HT STA 2G4 satisfies the conditions described in 11.14.6.
November 2008
Peter Loc & Kiran
Slide 4
doc.: IEEE 802.11-08/1238r4
Submission Slide 4
Reasons for accepting the CID 10025 comment resolution as proposed
To remove the notion that the recommendation in the current IEEE802.11n Draft 7.0 creates a class of 802.11n devices that knowingly interfere with non 802.11 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
November 2008
Peter Loc & Kiran
Slide 5
doc.: IEEE 802.11-08/1238r4
Submission Slide 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
11-08-0880-00-0vht-reponse-to-official-comments 11-08-1101-03-000n-additional-40-mhz-scanning-proposal 11-08-0992-00-000n-20-40-mhz-11n-interference-on-bluetooth 11-08-1140-00-000n-11n-40-mhz-and-bt-coexistence-test-results 11-08-0880-00-
0vht-reponse-to-official-comment 19-08-0027-02-0000-ieee-802-11n-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
November 2008
Peter Loc & Kiran
Slide 6
doc.: IEEE 802.11-08/1238r4
Submission Slide 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
November 2008
Peter Loc & Kiran
Slide 7
doc.: IEEE 802.11-08/1238r4
Submission
Test Setup
Agilent Spectrum Analyser
~10m
11n - AP
11n - STA
Bluetooth
dongle
Bluetooth
Headset
~1m
November 2008
Peter Loc & Kiran
Slide 8
doc.: IEEE 802.11-08/1238r4
Submission
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
November 2008
Peter Loc & Kiran
Slide 9
doc.: IEEE 802.11-08/1238r4
Submission
Nominal Behaviour
– Start (11n off): 0s
– 11n-on : ~10s
– 11n-switch-BW : ~60s
– 11n-switch-BW : ~120s
• Top : on@40MHz 20MHz 40MHz
• Bottom : on@20MHz 40MHz 20MHz
off 40MHz 20MHz 40MHz
off 20MHz 40MHz 20MHz
November 2008
Peter Loc & Kiran
Slide 10
doc.: IEEE 802.11-08/1238r4
Submission
Worst Case
– Start (11n off) : 0s
– 11n-on : ~10s
– 11n-switch-BW : ~130s
• Top : on@40MHz 20MHz
• Bottom : on@20MHz 40MHz
off 40MHz 20MHz
off 20MHz 40MHz
November 2008
Peter Loc & Kiran
Slide 11
doc.: IEEE 802.11-08/1238r4
Submission
AFH-Settling TimesNominal Startup
Transition Trial 1 Trial 2 Trial 3 Average
on@20MHz 25s 29s 24s 26s
on@40MHz 29s 33s 31s 31s
40MHz->20MHz 0s 1ms? 0s 0s
20MHz->40MHz 10s 5s 6s 7s
Worst Case Startup
on@20MHz 62s
Trials are all randomly started and are
unrelated across the rows/columns
? : a blip was heard
on@40MHz 86s
40MHz->20MHz 0s
November 2008
Peter Loc & Kiran
Slide 12
doc.: IEEE 802.11-08/1238r4
Submission
11n-40MHz Bluetooth 11n-20MHz
40MHz(adapt) 20MHz(adapt)
Explanation (AFH)
November 2008
Peter Loc & Kiran
Slide 13
doc.: IEEE 802.11-08/1238r4
Submission
Explanation (on a BW switch)
20MHz 40MHz 40MHz20MHz (needs time to adapt) (has no extra interference)
(lower available Bandwidth) (extra Bandwidth)
November 2008
Peter Loc & Kiran
Slide 14
doc.: IEEE 802.11-08/1238r4
Submission
Conclusions
Bluetooth AFH-adaptation Time11n 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
disruptionAfter AFH adapts, the effect of 11n is not perceived11n Bandwidth-switch
40MHz 20MHz does not affect Bluetooth20MHz 40MHz results in ~5-10s disruption
November 2008
Peter Loc & Kiran
Slide 15
doc.: IEEE 802.11-08/1238r4
Submission
Proposal part 1
1) Add non 802.11n 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 10025
In subclause 7.3.2.57.5, use the reserved bit B3 of the Extended Capabilities field for the HT AP or HT STA to declare its support for non-802.11 radio scans.
In subclause 11.14.3.2, insert after line 37 , page 223:Before an FC HT AP 2G4 or FC HT STA 2G4 that is capable of detecting non-802.11 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-802.11 radios.
In subclause 11.14.3.2, insert after line 65 , page 223, the following:An FC HT AP 2G4 that is capable of detecting non-802.11 radios shall keep the value of 20/40 Operation Permitted to FALSE if a presence of non-802.11 radio is detected.
Insert the following paragraph at the end of subclause 11.14.5, page 230, after line 13An FC HT STA 2G4 that is associated with an FC HT AP 2G4 and is capable of performing non-802.11 radio scans (bit B3 of the Extended Capability field is set to 1) shall perform at least one non 802.11 radio scan every dot11BSSWidthTriggerScanInterval seconds., unless the FC HT STA 2G4 satisfies the conditions described in 11.14.6.
November 2008
Peter Loc & Kiran
Slide 16
doc.: IEEE 802.11-08/1238r4
Submission
Proposal part 2
2) Adopt the “non-802.11 radio scan” procedure described on slide 10 of the document11-08-1101-03-000n-additional-40-mhz-scanning-proposal (John R. Barr,
Motorola Inc.)
The “non-802.11 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=2405 + 5(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-802.11 radio scan” result is positive otherwise it is negative.
November 2008
Peter Loc & Kiran
Slide 17
doc.: IEEE 802.11-08/1238r4
Submission
Final Conclusion
Accepting this proposal will surely alleviate concerns on coexistence between 40 MHz capable 802.11n devices and others that share the 2.4 GHz band
This will speed up approval of the 802.11n draft during the sponsor ballot.
Pay now to save later
November 2008
Peter Loc & Kiran
Slide 18
doc.: IEEE 802.11-08/1238r4
Submission
Thank You
Q&A
