White Space vote nears

The NYC Council Tech Committee recently held a public hearing after the Broadway and TV industries lobbied for a resolution urging the FCC to withhold approval of White Space Devices (WSDs) for broadband access – the concern being that they would interfere with wireless microphones and DTV transmissions


The FCC, as it now stands, will vote on Nov 4

Freepress is strongly advocating the public to encourage the FCC to approve WSDs.

The FCC’s engineers, after conducting tests, released a report on Oct 16.

In summary it concludes:

These devices have been developed to demonstrate
capabilities that might be used in unlicensed low power
radio transmitting devices that would operate on
frequencies in the broadcast television bands that are
unused in each local area. At this juncture, we believe
that the burden of “proof of concept” has been met. We
are satisfied that spectrum sensing in combination with
geo-location and database access techniques can be used
to authorize equipment today under appropriate technical
standards and that issues regarding future development
and approval of any additional devices, including
devices relying on sensing alone, can be addressed.

Reading the FCC engineer’s report, however, it seems far
from giving WSDs an entirely clean bill of heath.

* Several tests were performed with DTV signals present
in adjacent channels. These tests showed that in the
presence of moderate-to-strong signals in a first
adjacent channel, the detection threshold sensitivity of
all of the devices was severely impacted. For some of
the devices, the degradation in the detection
sensitivity was as much as 60- 70 dB. In some cases, the
degradation was such that the detection threshold could
not be measured. This could impact significantly the
ability of the devices to reliably detect TV signals
within stations’ service areas.

* The Microsoft, Philips and I2R devices were tested for
their ability to sense for the presence of wireless
microphones (both FM/analog and digital) operating
within UHF TV channels. With no other signals present,
the devices were able to detect wireless microphones at
levels ranging from -103 dBm to -129 dBm depending on
the type of microphone, and the device. In the presence
of DTV signals in adjacent channels, the detection
threshold was degraded such that it affected the ability
of the devices to reliably detect the microphone

On Oct 17 the TV interests filed an ‘Emergency Request’ asking that any vote be delayed
to allow for a 70 day response period to the report

On Oct 20 Rural Broadband interests filed an ‘ex parte’ letter emphasizing that WSDs
should be 1) mobile, and 2) unlicensed.

About joly

isoc member since 1995

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