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Carl, Thank
you for your detailed response. Let me try to summarize my concerns in this
response. They relate to wireless microphones and professional installation. Wireless
Microphones I
am not trying to question the accuracy of the technical work within 802.18. My
concern is that the IEEE is recommending to the FCC that they regulate how
industry ensures that Part 15 devices do not interfere with Part 74 devices.
Typically the FCC limits power and power spectral density (PSD) of Part 15
devices but does not specify rules for spectrum sharing. They typically leave
any spectrum sharing designs to the industry. You
mention my position as chair of 802.19 Coexistence TAG which is a very good
point. By analogy, 802.19 did not regulate in the recent rules change how the
wireless working groups should ensure coexistence, we just are requiring that
they do coexist, using any design they like, and then show that the new
standard coexists with current standards. So 802.19 did not tell the wireless
working group how to do their job, just that they need to show that they did do
there job. However,
I do understand that this band is different than the ISM bands so I appreciate
that it may be necessary for the FCC to set additional regulation on industry. So
I will accept your response on the Part 74 devices and will withdraw my
recommendation to remove those paragraphs. Professional Installation I
do not accept that argument that GPS systems and database systems are always
unreliable, and hence the only valid method of installation is a professional.
I believe that in many cases GPS and a database can be made reliable and can be
used for installation. In the case that they do not work professional
installation is also available. So I believe that both methods of installation
should be allowed by the FCC. I
maintain my recommendation to add text to the document allowing for either
professional or GPS/Database types of installation. Sincerely, Steve From: Carl R.
Stevenson [mailto:wk3c@wk3c.com] Steve, Response to your comments in line below
for context ... (for those whose mail clients may not
support HTML e-mail and would, therefore, make the text below VERY ugly, I am
attaching a .pdf version of this message, which I assume that everyone should
be able to find readable) From:
Shellhammer, Stephen J [mailto:stephen.j.shellhammer@intel.com] Carl,
I vote No but will change my No to a Yes if my recommendations listed below are
implemented.
My fundamentally concern is that, In this response to the
FCC NPRM the IEEE is recommending to the FCC that they place additional
restrictions on IEEE 802 devices above and beyond what the FCC is proposing in
the NPRM. The objective is to gain access to the TV bands ON A
NON-INTERFERING BASIS TO LICENSED INCUMBENT SERVICES. The studies that
have been conducted show, quite conclusively, that some of the proposals in the
FCC NPRM have shortcomings that, if implemented "as is," would
result in interference to licensed incumbent services. That would be a
major disaster. Systems would have to be shut down when they caused
interference and the result would both have a negative impact on producers and
users of those systems and would "poison the well" for future
unlicensed under licensed spectrum sharing opportunities until long after most
of us on the EC are likely to be retired. Specific comments follow ... Special Protection for Part 74 Wireless Microphones The FCC NPRM stated that because of
the FM capture effect and a strong received signal strength of the wireless
microphones, “the likelihood of interference from unlicensed device
signals is therefore low such that unlicensed use should generally be
compatible with wireless microphones”, and imposes no further
restrictions on unlicensed 802-type devices. Since my first job as an
RF engineer many (many) years ago was designing studio/broadcast quality
wireless microphone systems, I have some significant personal and
professional experience in this area. Yes, FM does exhibit a
capture effect, but it is NOT the be-all/end-all that can/should
be relied upon. There are other factors, such as intermodulation,
front-end overload, etc. which must be considered in the equation. Additionally, the
assumption that signal strengths in wireless microphone systems are so strong
that there is no issue is simply false. Most wireless microphones are
relatively low power devices and hand effects on handheld ones and body effects
on body pack ones are very significant, further reducing signal strength at the
wireless microphone receiver to the point where link margins can be, and
frequently are, slim. I could go on, but
suffice it to say that the studies conducted by 802.18 and 802.18 SG1 in
cooperation with the wireless microphone folks show that simply relying on FM
capture effect will NOT afford Part 74 wireless microphone systems the
protection to which they are legally entitled. However, the IEEE 802 response to
the FCC NPRM recommends adding the following requirements on Part 15 unlicensed
devices: 1. The Part 15 must be able to sense the
operation of a Part 74 device Everyone agreed that a sensing mechanism would be required to sense
channel occupancy by TV stations. Of that, there was no dispute. The
threshold proposed in the Comments for wireless microphones is less
stringent than that proposed for sensing TV stations, and thus will be
easier to meet (by 10 dB). The differential is based on the
difference in modulation/spectral characteristics between wireless microphones
and TV signals. Also, since the sensing mechanism will
already be required and in place to sense the TV
stations, "where's the rub?" However,
while the proposed -107 dBm sensing threshold for wireless microphones, will,
as stated in the comments, provide SOME DEGREE of protection to Part 74
wireless microphones, it will not provide robust protection in many
circunstances (never the less, the wireless microphone folks and the
broadcasters agreed to this less than perfect number in recognition that, due
to their different spectral characteristics, meeting a more stringent number
WOULD make things more difficult for unlicensed devices). By the way, the
number originated in studies done by 802 folks, not from the wireless
microphone folks, and was derived as a "best effort" attempt to
afford them the protection to which they are entitled and be responsible
sharing partners. These
devices ARE entitled to protection. Under Part 74, they are secondary to
the primary TV broadcast service, but secondary "trumps" Part 15
unlicensed every day (and twice on Sunday, as they say). If we interfere,
they will legally be justified in demaning that we cease operation.
Again, that would be a "very bad thing." (I would think that as
Chair of the Coexistence TAG, you would favor being good sharing partners -
especially when doing so essentially comes at no cost.) 2. The Part 15 device
must be able to sense the presence of a yet-to-be defined beacon emitting from
a Part 74 device The idea of a
beacon was offered up by the wireless microphone folks as a way of helping us
protect them, despite the fact that as licensed users they are not required to
do ANYTHING to help us protect them. They COULD legally, just say
"Protect us as we are, it's YOUR problem." but have not done
so. Fielding beacons
to increase our ability to sense them an provide a small, more
robust "bubble of protection" around certain critical venues
is something that they
offered in the
spirit of cooperation. Doing so will cost THEM
something (the cost of providing the beacons) - again something that they were
under no obligation to offer up, but that they did in the spirit of
cooperation. The idea of the
beacon is intended to avoid the situation where unlicensed devices could
"trash" critical operations at major events. Imagine the
ramifications of our devices trashing the SuperBowl, the recent national political
conventions, coverage of major news event like 9/11, and other events of that
magnitude, where there are routinely on the order of 100-200 or more wireless
microphones (including "in-ear monitors" and other
"intercom-like" systems in operation) - all of which fall under
Part 74, which, again, is entitled to protection from harmful interference from
unlicensed devices. Yes, the beacon is
"yet-to-be-defined" but the concepts that have been discussed are
VERY simple and, given the requirements for a sensing mechanism for the primary
TV signals, would cost the developers of 802 devices intended to operate in the
TV bands virtually nothing (quite likely absolutely nothing). The wireless
microphone people are committed to working cooperatively with us to further
define the beacon concept and parameters in a way that will make it simple for
them to build cost-effective beacon devices and for us to detect those beacons. I don't
believe (and 802.18 did not believe) that taking the attitude of "We don't
care if they're licensed and entitled to protection or not, we'll just ignore
the results of our studies and rely on the FCC to ignore the rights and
legitimate needs of the wireless microphone folks." would be an appropriate
approach for 802 to take. Again, I would hope that, as the Chair of our
Coexistence TAG, you would
agree.
It seems that the IEEE 802 is requesting additional
restrictions be placed upon its devices above and beyond those recommended in
the FCC NPRM. The fundamental
requirement to gain (and keep) access to this valuable spectrum is to protect
licensed services. Since our studies over the course of an entire year
indicated that the FCC's NPRM proposal vis a vis wireless microphones under Part
74 was less than adequate, we believed that it was appropriate to suggest
something that all parties involved agreed was reasonable (and, again, the
wireless microphone folks have been VERY reasonable). Just because the FCC proposes
something in an NPRM does not mean it is not subject to discussion or
suggestions for alternatives - in fact, that's why the comment/reply comment
process exists - in recognition that inital proposal may not
always address all issues adequately and to seek comment that will help
the FCC end up making better decisions. I have heard rumors of suggestions from certain parties that
"The FCC doesn't really care about protecting Part 74 wireless microphones
going forward, so why should we do anything or say anything that would support
their (current) right to protection." I believe that that approach
is irresponsible and based on a flawed view of the FCC's approach to/intentions
in this matter that, in turn, is based on reading too much into the NPRM
proposal language (which again, our studies showed would be inadequate). In fact, I just got off the phone with a very senior
level official in the FCC's OET seeking clarification on this issue, and he
assured me that 1) they have NO intention of abandoning the protection rights
of Part 74 secondary devices like wireless microphones, and 2) they have
been very impressed with both the technical presentations and the sense of
responsible, cooperative outreach towards the unlicensed community that has
been evidenced by the wireless microphone folks in their ex parte presentations
at the FCC. It does not seem like that is
in the best interest of IEEE 802. It does not seem to me
that it is in the best interest of IEEE 802, or the unlicensed industry and its
users in general, to fail to propose more viable mechanisms to help assure
that we can, in fact, coexist, since coexistence (in this case not causing
harmful interference to licensed users) is a fundamental requirement for
gaining, and maintaining, access to the spectrum in question. Unlicensed under licensed
sharing is a VERY different ball game than the unlicensed vs. unlicensed
"food fights" in the ISM bands. Recommendation Remove Paragraphs 26, 27, 36 and 37. Removal of these paragraphs files in the face of our
own technical studies which resulted in the proposals therein. It would
also fly in the face of our obligation to afford these licensed uses
protection to which they are entitled. While both
the 802 folks and the wireless microphone and broadcast folks who were involved
in the studies and discussions that resulted in these paragraphs agreed (and
the wireless microphone and broadcast folks accepted) that the
proposals in these paragraphs do not guarantee 100% absolute protection to
Part 74 wireless microphones, we collectively believed (including the wireless
microphone and broadcast folks) that the proposals in the subject
paragraphs represent a reasonable and responsible compromise. In summary,
the text in the subject paragraphs was agreed by ALL parties participating in
the discussions in 802.18 (the document was approved unanimously in 802.18),
including the voting members from the organization that I am given to
understand has subsequently raised these issues and wants the paragraphs deleted. To
remove these paragraphs would represent a substantive change to the
document that would exceed the editorial authority given by 802.18 in its
approval motion and would, in my *personal* view be an affront to the
cooperative spirit that the wireless microphone and broadcast folks brought to
the table on this issue. Finally,
backing out on this compromise, that all involved agreed was reasonable,
at the 11th hour and 59th minute would also, I fear, cause ALL of the
incumbents that have been working with us to legitimately question whether they
can rely on us to keep our agreements with and committments to them in the
future. Requirement for Professional Installation The FCC NPRM proposes two
installation methods for the fixed/access class:
1. Geolocation coupled with database access
Geolocation can be problematic (GPS
doesn't work well indoors or in heavily shadowed areas, for example) and WHAT
database? The FCC database of TV transmitters is, by all accounts full of
inaccuracies and omissions (meaning no disrespect to the FCC as we all know
that they have limited resources) and is not likely to be improved and/or
maintained to a sufficient level of accuracy, due to resource
limitiations. These factors, in our view, rendered dependence on this
mechanism to protect TV broadcast service inadequate as a sole/primary means. Likewise, geolocation/database
techniques would prove inadequate to protect Part 74 users. These considerations are, we
believe, explained sufficiently in other sections of the comments.
2. Professional installation In paragraph 25 of the IEEE response
to the FCC NPRM it states that GPS may be the most practical means of
protecting Part 90 devices. Part 90 devices have
allocations in TV channels 14-20 in the top 13 urban areas of the However, the title of
paragraph 28 states that professional installation is required and does not
allow for GPS with database access as an alternative mechanism. Professional installation
is recommended only for the fixed access base station and a
"one-time" GPS geolocation of such stations is proposed, rather than
requiring all fixed access devices to have an embedded GPS receiver.
(Obviously "personal portable" devices cannot be professionally
installed, and this paragraph does not deal with category of operation at
all.) Furthermore, the text of that section goes to some length to argue
against a professional installation requirement for CPE's (user terminals). Once again, relying on
GPS/database as the sole, or primary, means of determining channel availability
is, per our studies, insufficiently robust. Once again the IEEE is
recommending that the FCC place additional requirements on Part 15 devices
above and beyond those recommended in the FCC NPRM. Once again, it does not
seem to me that it is in the best interest of IEEE 802, or the unlicensed
industry and its users in general, to fail to propose more viable mechanisms
to help assure that we can, in fact, coexist, since coexistence (in
this case not causing harmful interference to licensed users) is a fundamental
requirement for gaining, and maintaining, access to the spectrum in question. Unlicensed under licensed
sharing is a VERY different ball game than the unlicensed vs. unlicensed
"food fights" in the ISM bands. Recommendation The following words should be added
to the beginning of Paragraph 28: “In instances where geolocation with
database access is not used, “. These same words should also be
added to the end of the heading immediately preceding Paragraph 28. Since we determined (over
the course of a year's studies) that the "geolocation with database"
technique was problematic as a sole/primary interference prevention
mechanism, for the reasons outlined in the document, it would be inconsistent
to appear to be advocating it as a (presumbably, if we were to make the
change you propose) viable option. I also believe that these
changes are sufficiently substantive, and contradict the overall
conclusions/explainations elsewhere in the document, as to exceed the editorial
authority granted in 802.18's motion to approve the document. Regards, Steve _________________ Steve Shellhammer Intel Corporation (858) 391-4570 Summary 802.18 and 802.18 SG1 (which was tasked
with studying the issues surrounding gaining access to the TV bands on an
unlicensed, non-interfering basis) have studied these issues and worked with
the incumbents for over a year on studies, discussions, and compromises
designed to meet everyone's legitimate needs in a reasonable manner. Everyone and anyone who had an interest
and the desire to participate in those studies, discussions, and
compromises was, fo course, fully welcome to do so. If seems unreasonable to me for parties -
who I am given to understand WERE represented in the work of 802.18/802.18 SG1
and whose representatives there voted to approve this document or other parties
who chose not to avail themselves of the opportunity to participate at
all - to "come out of the woodwork" at the 11th hour and 59th
minute with attempts to back out on these carefully and delicately crafted
compromises, that all involved in the process agreed were reasonable and
acceptable. Again, I fear, that such a move would
cause ALL of the incumbents that have been working with us to legitimately
question whether they can rely on us to keep our agreements with and
committments to them in the future. Regards, Carl R. Stevenson President and Chief Technology Officer WK3C Wireless LLC Where wireless is a passion, as well as a
profession. SM ——————————————————————————————————— Wireless Standards,
Regulatory & Design Consulting Services phone: +1 610 965
8799 cellular: +1 610 841 6180 e-mail: wk3c@wk3c.com web: http://www.wk3c.com |