| Thread Links | Date Links | ||||
|---|---|---|---|---|---|
| Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
|
Hi All, As discussed in 802.11 REG today: http://apps.fcc.gov/ecfs/document/view?id=60001462642 page 4 More
generally,
Google’s
measurements
illustrate
two
important
principles
that
should
inform
the
determination
of
maximum
protected
service
areas.
First,
maximum
protected
service
areas
will
almost
always
be
substantially
smaller
than
census
tracts.
The
census
tract
that
encompasses
Google’s
test
area
in
Mountain
View,
California,
for
example,
is
27.6
km2,
or
55
times
larger
than
the
calculated
maximum
coverage
area
for
Category
A
devices
operating
at
street
level.9
Second,
the
measurements
illustrate
the
dramatic
impact
of
clutter
on
CBSD
signal
propagation.
As
set
forth
in
greater
detail
in
the
attached
Clegg
Declaration,
measured
path
loss
exceeded
free
space
path
loss
predictions
by
56.7
dB
on
average,
and
by
as
much
as
85.3
dB,10
over
distances
less
than
1
km.
Even
Longley-Rice
prediction
substantially
understated
propagation
losses:
measured
path
loss
exceeded
the
Longley-Rice
predictions
by,
on
average,
45.7
dB,
and
by
as
much
as
78.1
dB.11
Both
the
free
space
and
Longley-Rice
models
underestimated
path
loss
in
more
than
99.6%
of
measurements.12
This
is
true
even
though
the
test
area
is
a
lightly
cluttered
environment,
particularly
as
compared
to
rural
areas
with
dense
groves
of
trees,
or
urban
areas
with
tightly
packed,
tall
buildings.
The
impact
of
clutter
cannot
be
ignored
when
determining
the
reasonableness
of
claimed
CBSD
service
areas,
and
both
PA
licensees
and
SASs
should
be
expected
to
account
for
clutter
in
making
signal
propagation
calculations.
Ensuring
that
requests
for
protection
are
based
on
reasonable
engineering
considerations
will
support
intensive
use
of
the
band.
The
approach
proposed
above
allows
significant
flexibility
to
PA
licensees
while
ensuring
that
their
requests
are
not
grossly
excessive. ITU-R-REC-P.452-15 for ground and maritime radars see equation 57 and 57a https://www.itu.int/rec/R-REC-P.452/recommendation.asp?lang=en&parent=R-REC-P.452-16-201507-I ITU-R-REC-P.528-3 for aeronautical radars https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.528-3-201202-I!!PDF-E.pdf ITU-R-REC-P.619-1 earth to space https://www.itu.int/rec/R-REC-P.619/recommendation.asp?lang=en&parent=R-REC-P.619-1-199203-I ITU-R-REC-P.618-12 earth-to-space communications https://www.itu.int/rec/R-REC-P.618/recommendation.asp?lang=en&parent=R-REC-P.618-12-201507-I Best Regards, petere Peter Ecclesine, Technology Analyst 170 W. Tasman Dr, MS SJ-18-3 San Jose, CA 95134-1706 +1-408-527-0815 FAX +1-408-525-9256 ‘without prejudice’ U.C.C. 1-308 If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-REG and then press the LEAVE button. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html _______________________________________________________________________________ |