FCC Seeks Feedback on LTE-to-DTV Interference
Comment deadline is July 11
June 23, 2014
—The FCC Office
of Engineering and Technology is soliciting comments on LTE-to-DTV interference. The OET seeks to supplement the record in the
incentive auction proceeding by inviting comment on measurements
Long-Term Evolution interference into digital television receivers conducted
by OET engineers.
In the interference Public Notice, OET invited comment on a methodology for predicting inter-service interference, or ISIX. For purposes of that methodology, OET assumed
that wireless services operating in the new 600 MHz band will appear
noise-like to DTV receivers and hence, that the interference potential from
LTE will be nearly identical to DTV-to-DTV interference. In addition, OET incorporated an off-frequency
rejection factor as a function of varying degrees of spectral overlap due
to filter roll-off in the misaligned future wireless blocks and existing TV
channels in the 600 MHz band. OET also
added 0.8 dB to the interfering wireless signal to account for the possibility
of co-channel power from multiple wireless blocks affecting one 6 MHz TV
channel. Several commenters raised concerns about these
assumptions which form the basis for the D/U ratios of Table 8, the OFR values
of Table 9, and the assumed effective radiated power in Table 10 of the Public Notice.
In April 2014,
OET engineers tested the characteristics of LTE-into-DTV interference in the
FCC Laboratory, and the results of those measurements are presented in the
attached report. As explained in the
report, four DTV receivers were tested in order to obtain a reasonable
indication of their behavior in the presence of an interfering LTE eNodeB
the Consumer Electronics Association submitted measurements of LTE-to-DTV
interference on six newer model television receivers and two older model
OET seeks comment on whether
these measurements in its report, in conjunction with CEA’s measurements, support the D/U
ratios, OFR, and power adjustments that appear in the Public Notice.
OET also seeks comment on the
relevance of the measurements associated with two receiver models that are more
than seven years old. The report
contains measurements of a 2007 model year receiver and the CEA report contains
measurements of a 2006 model year receiver.
OET anticipates that these receivers will no longer be commercially
available and will be approaching the end of their useful lifecycle at the time
of the wireless build out in the 600 MHz Band.
Comments may be filed
electronically using the Internet by accessing the ECFS: http://fjallfoss.fcc.gov/ecfs2/. Comment deadline is July 11, 2014.