Although I have high hopes for TVWS I also expect that, 10-20 years from now, we will look back on the TV White Spaces decision and recognize it as a breakthough in getting access to all otherwise unused spectrum, for example in the 3 GHz - 9 GHz range.

1. Significance
of
TV
White
Spaces
Brough
Turner
netBlazr
brough@netblazr.com

2. Disclaimer
• I
look
forward
to
great
things
from
TVWS
• I
am
worried
adop@on
will
be
slowed
by:
– Law
suits
– Restric@ve
requirements
for
an
antenna’s
Height
Above
Average
Terrain
(HAAT)
– Adjacent
channel
restric@ons
limit
urban
use
and
limit
the
poten@al
market
size
• But
Carl
invites
me
because
I’m
disrup@ve!
4
October
2010
2

3. Long
term
significance
• License-­‐exempt
access
to
otherwise
unused
spectrum,
on
a
secondary
use
basis,
despite
powerful
vested
interests
4
October
2010
3

4. Long
term
significance
• License-­‐exempt
access
to
otherwise
unused
spectrum,
on
a
secondary
use
basis,
despite
powerful
vested
interests
• 20
year
dream:
similar
access
to
unused
spectrum
between
3
GHz
and
9
GHz
• Why?
Higher
spectrum
more
useful
!
4
October
2010
4

5. Spectrum
Myths
TV
Spectrum
is
“beach
front”
spectrum
5

6. Spectrum
Myths
TV
Spectrum
is
“beach
front”
spectrum
• Based
on
20th
century
technology,
not
physics!
– Travels
farther
thru
the
air
–
No!
– Thru
windows
–
roughly
the
same
– Goes
thru
masonry
–
yes,
with
50,000
waas!
6

7. Higher
frequency
• Tighter
Fresnel
zone
• Less
clearance
required
4
October
2010
7

8. Noise
4
October
2010
8

9. Free
space
path
loss
9

10. Free
space
path
loss
Seems
to
say
more
,
more
loss
10

11. Free
space
path
loss
Seems
to
say
more
,
more
loss
But
this
equa@on
encapsulates
two
effects:
Actual
path
loss
(independent
of
frequency!
)
Receiving
antenna
aperture
(assumed
to
be
½
wavelength)
11

12. Free
space
path
loss
Seems
to
say
more
,
more
loss
But
this
equa@on
encapsulates
two
effects:
Actual
path
loss
(independent
of
frequency!
)
Receiving
antenna
aperture
(assumed
to
be
½
wavelength)
5
GHz
photons
go
just
as
far
as
50-­‐700
MHz
photons
!
12

13. Refrac@on
and
reflec@ons
Shorter
wavelength
-­‐
more
reflec@ons,
refrac@on

“Mul@Path”

“Ghosts”
if
a
single
receiver
13

14. MIMO:
Mul@ple
Input
Mul@ple
Output
• Mul@ple
paths
improve
link
reliability
and
increase
spectral
efficiency
(bps/Hz),
range
&
direc@onality
14

15. Beamforming
~2014:
>300
Mbps
Wi-­‐Fi
to
~1
Km
at
mass
market
prices
…
4x4
MIMO
with
8
antenna
elements
15

16. Beamforming
~2014:
>300
Mbps
Wi-­‐Fi
to
~1
Km
at
mass
market
prices
…
4x4
MIMO
with
8
antenna
elements
16

17. Beamforming
~2014:
>300
Mbps
Wi-­‐Fi
to
~1
Km
at
mass
market
prices
…
4x4
MIMO
with
8
antenna
elements
17

18. MIMO
&
Beamforming
• Ideal
antenna
element
separa@on
>=
½
wavelength
– 2.1
meters
at
70
MHz
– 21
cm
at
700
MHz
• But
only
– 2.5
cm
for
5.8
GHz
Wi-­‐Fi
Ruckus
Wireless
Wavion
Networks
D-­‐Link
DAP-­‐2553
18

19. Thank
You
Brough
Turner
brough@netblazr.com