May 2007
doc.: IEEE 802.19-07/0014r0
IEEE P802.19
Wireless Coexistence
May 2007 Minutes
Date: 2007-05-16
Author(s):
Name
Stephen R Whitesell
Company
VTech
Communications
Address
2 Shannon Ct
Howell, NJ 07731
Phone
732 751 1079
Email
swhitesell@vtech.ca
Abstract
This document provides a record of the minutes for the May 2007 meeting of the IEEE 802.19
Coexistence Technical Advisory Group.
Notice: This document has been prepared to assist IEEE 802.19. It is offered as a basis for discussion and is not binding on the
contributing individual(s) or organization(s). The material in this document is subject to change in form and content after
further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution,
and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE
Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit
others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and
accepts that this contribution may be made public by IEEE 802.19.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http://
ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s),
including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents
essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the TAG of patent
information that might be relevant to the standard is essential to reduce the possibility for delays in the development process
and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair
<Shellhammer@ieee.org> as early as possible, in written or electronic form, if patented technology (or technology under patent
application) might be incorporated into a draft standard being developed within the IEEE 802.19 TAG. If you have questions,
contact the IEEE Patent Committee Administrator at <patcom@ieee.org>.
Submission
page 1
Steve Whitesell, VTech
May 2007
doc.: IEEE 802.19-07/0014r0
The IEEE 802.19 Coexistence Technical Advisory Group (TAG) met in conjunction with the IEEE 802
Wireless Interim Session in Montreal, QC during the week of May 14-18, 2007. Minutes for each of the
meetings held during the week are provided below.
Tuesday PM1
Chair Steve Shellhammer called the meeting to order at 1:40 pm. He reviewed the objectives and the
meeting times for the week as given 07/0012r0. He noted that although there were four sessions assigned
for the week, he believed we would only need the PM1 and PM2 sessions on Tuesday. He then reviewed
the detailed agenda. John Barr asked that we add an agenda item on discussion of 802.11n coexistence.
This was inserted as the first item after the opening business for the Tuesday PM1 session. There was no
objection to accepting the agenda as modified in 07/0012r1.
Steve S then read the IEEE patent policy as found on the set of 5 slides identified as “Highlights of the
IEEE-SA Standards Board Bylaws on Patents in Standards” available at the IEEE PATCOM web site.
Following this presentation, Steve Shellhammer read a general statement indicating that Qualcomm might
have intellectual property that could be essential to the practice of the standard. He further indicated that
if they do, they will comply with all IEEE requirements regarding IPRs and disclosure in a timely
manner. He then asked if anyone else wished to make a disclosure. No one else spoke up.
Steve Whitesell reviewed the minutes from the March 2007 meeting as provided in 07/0008r0. There was
no objection to accepting the minutes as presented.
John Barr then led discussion of his 802.11n coexistence concerns. He presented 11-07/0707r0, which
contains his 802.11n ballot comment expressing the opinion that use of 40 MHz channels in the 2.4 GHz
band should not be allowed by the 11n amendment. John indicated that such 40 MHz channels could not
coexist with the over 1 billion Bluetooth® (BT) devices in service in this frequency band. He pointed out
that when 802.15.1 standard covering BT was published, there were coexistence issues between it and
existing 802.11b devices. The 802.15.2 Recommended Practice on coexistence was subsequently created,
and the BT Special Interest Group (SIG) switched to Adaptive Frequency Hopping (AFH) as a
noncollaborative means of having BT devices coexist with 20 MHz 802.11 channels in the 2.4 GHz band.
John explained that AFH allows BT devices to recognize the 20 MHz 802.11 devices and adapt their
hopping to a different part of the 2.4 GHz band. However, he contends that BT products that implement
AFH have not been designed to detect the lower power but wider bandwidth 40 MHz channels. As a
result, both 802.11n and BT devices will experience significant degradation of service. His proposal was
to drop 40 MHz from 2.4 band. He indicated that 802.11n had made a counter proposal to allow an STA
to ask the AP to set a bit that stops 40 MHz, but there is no way for a BT radio to transmit that info to the
AP. If the 40 MHz wide channel is not removed from the standard, John contends it is 802.11n’s turn to
implement a non-collaborative coexistence mechanism, such as detecting the existence of BT devices and
falling back to 20 MHz channel operation. BT AFH (adaptive FH).
Steve Whitesell mentioned that that many cordless telephones are “Wi-Fi aware” and use AFH to move to
another part of the frequency band in the presence of an 802.11 WLAN. He did not know how well they
wwould coexist with 11n devices using 40 MHz channels. Andrew Cowans talked about experiences he
has had with 20 and 40 MHz 802.11. Performance degrades. He has a document that talks about
different modeling approaches that he will provide to Steve S. John indicated he would be making a
similar presentation to the 11n coexistence group during the Wednesday PM1 session.
Steve S then presented the work he is doing on drafting the Recommended Practice as shown in
07/0007R1. He indicated he has decided to take responsibility for drafting the document because others
are not stepping up to the task. Anyone who wants to help with the drafting is more than welcome to do
so. He reviewed the Table of Contents, pointing out that Clause 5 provides a short general description of
Submission
page 2
Steve Whitesell, VTech
May 2007
doc.: IEEE 802.19-07/0014r0
how one goes about assessing coexistence and Clause 6 describes the remainder of the document
Structure. Clause 7 outlines the coexistence assessment process, which consists of three steps: selecting
the coexistence scenario(s), selecting the coexistence metric(s), and selecting a method to evaluate the
metric.
Clauses 8 describes possible coexistence scenarios. It includes two fairly complete descriptions. One is
for two small networks in which the interference of interest is between a single station in one netweork
and a single station in another network. The other is for two large networks where the interference
cannot be isolated to single stations and must be treated as an aggregation of all the individual signals.
There are also placeholders for two additional scenarios: dynamic frequency selection and listen-beforetalk.
Steve S briefly mentioned Clause 9, which will provide descriptions of several possible metrics, and
Clause 10, which will provide methods for estimating the metrics in the various scenarios. Several
worked examples are intended to be included as informative annexes.
The meeting was recessed at 3:02 pm.
Tuesday PM2
Steve S reconvened the meeting at 3:55 pm. He presented 07/0010r0 on clear channel assessment energy
detection (CCA-ED). The contribution was in response to concerns about 802.11y coexisting with
802.16h. It discusses CCA-ED by 11y operating in the presence of 16h, but with 16h’s adoption of a
listen-before-talk (LBT) protocol, it should apply in the reverse direction as well. Steve S noted that
sensing times vary inversely with channel bandwidth because this allows the same silicon to be used. The
energy detection statistic is a measure of average power and can be compared with a detection threshold
specification. It is based on a binary hypothesis: are you detecting noise or signal plus noise?
The results suggest the exposed node problem is not very bad, but the hidden node problem is. These
conclusions are based on multiple observation results for fixed and portable scenarios. The exposed node
is potentially a big problem for cognitvive radio DFS systems that have low thresholds and always back
off. They don’t cause interference to others, but never get to transmit. Steve S will present again during
the next Conference Call on coexistence between 11y and 16h, which is scheduled for May 31 at 11:00
ET. Additional 11y/16h calls are scheduled for June 14 and June 28.
The meeting was adjourned for the week at 5:18 pm.
Attendance
Name
Mark Austin
John Barr
Andrew Cowans
Steve Shellhammer
Steve Whitesell
Submission
Affiliation
Ofcom
Motorola
Ofcom
Qualcomm
VTech
page 3
Tue
PM 1
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Tue
PM 2
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Steve Whitesell, VTech
May 2007
doc.: IEEE 802.19-07/0014r0
References:
11-07/0707r0 – LB97 CID 170 20-40 Coex, Barr
19-07/0007r1 – Initial Text for Recommended Practice, Shellhammer
19-07/0008r0 – March 2007 Minutes, Whitesell
19-07/0010r0 – Clear Channel Assessment Energy Detection (CCA-ED) in 802.11y, Shellhammer
19-07/0012r1 – May 2007 Agenda, Shellhammer
Submission
page 4
Steve Whitesell, VTech