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)
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 US. Their area of entitlement to
protection is defined as a radius surrounding specified geographical
coordinates. The "database" required to protect those 13 urban centers
is well-defined, very static, and could be contained in an
unlicensed device. This is a much more tractable situation than the
database issues surrounding protecting TV broadcast operations and Part 74
devices, so GPS and this (limited) "database" may be viable for the Part 90
case.
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
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