Goto Section: 15.321 | 15.401 | Table of Contents
FCC 15.323
Revised as of October 2, 2015
Goto Year:2014 |
2016
§ 15.323 Specific requirements for devices operating in the 1920-1930 MHz
band.
(a) Operation shall be contained within the 1920-1930 MHz band. The emission
bandwidth shall be less than 2.5 MHz. The power level shall be as specified
in § 15.319(c), but in no event shall the emission bandwidth be less than 50
kHz.
(b) [Reserved]
(c) Devices must incorporate a mechanism for monitoring the time and
spectrum windows that its transmission is intended to occupy. The following
criteria must be met:
(1) Immediately prior to initiating transmission, devices must monitor the
combined time and spectrum windows in which they intend to transmit for a
period of at least 10 milliseconds for systems designed to use a 10
milliseconds or shorter frame period or at least 20 milliseconds for systems
designed to use a 20 milliseconds frame period.
(2) The monitoring threshold must not be more than 30 dB above the thermal
noise power for a bandwidth equivalent to the emission bandwidth used by the
device.
(3) If no signal above the threshold level is detected, transmission may
commence and continue with the same emission bandwidth in the monitored time
and spectrum windows without further monitoring. However, occupation of the
same combined time and spectrum windows by a device or group of cooperating
devices continuously over a period of time longer than 8 hours is not
permitted without repeating the access criteria.
(4) Once access to specific combined time and spectrum windows is obtained
an acknowledgment from a system participant must be received by the
initiating transmitter within one second or transmission must cease.
Periodic acknowledgments must be received at least every 30 seconds or
transmission must cease. Channels used exclusively for control and signaling
information may transmit continuously for 30 seconds without receiving an
acknowledgment, at which time the access criteria must be repeated.
(5) If access to spectrum is not available as determined by the above, and a
minimum of 20 duplex system access channels are defined for the system, the
time and spectrum windows with the lowest power level may be accessed. A
device utilizing the provisions of this paragraph must have monitored all
access channels defined for its system within the last 10 seconds and must
verify, within the 20 milliseconds (40 milliseconds for devices designed to
use a 20 milliseconds frame period) immediately preceding actual channel
access that the detected power of the selected time and spectrum windows is
no higher than the previously detected value. The power measurement
resolution for this comparison must be accurate to within 6 dB. No device or
group of co-operating devices located within 1 meter of each other shall
during any frame period occupy more than 6 MHz of aggregate bandwidth, or
alternatively, more than one third of the time and spectrum windows defined
by the system.
(6) If the selected combined time and spectrum windows are unavailable, the
device may either monitor and select different windows or seek to use the
same windows after waiting an amount of time, randomly chosen from a uniform
random distribution between 10 and 150 milliseconds, commencing when the
channel becomes available.
(7) The monitoring system bandwidth must be equal to or greater than the
emission bandwidth of the intended transmission and have a maximum reaction
time less than 50xSQRT (1.25/emission bandwidth in MHz) microseconds for
signals at the applicable threshold level but shall not be required to be
less than 50 microseconds. If a signal is detected that is 6 dB or more
above the applicable threshold level, the maximum reaction time shall be
35xSQRT (1.25/emission bandwidth in MHz) microseconds but shall not be
required to be less than 35 microseconds.
(8) The monitoring system shall use the same antenna used for transmission,
or an antenna that yields equivalent reception at that location.
(9) Devices that have a power output lower than the maximum permitted under
this subpart may increase their monitoring detection threshold by one
decibel for each one decibel that the transmitter power is below the maximum
permitted.
(10) An initiating device may attempt to establish a duplex connection by
monitoring both its intended transmit and receive time and spectrum windows.
If both the intended transmit and receive time and spectrum windows meet the
access criteria, then the initiating device can initiate a transmission in
the intended transmit time and spectrum window. If the power detected by the
responding device can be decoded as a duplex connection signal from the
initiating device, then the responding device may immediately begin
transmitting on the receive time and spectrum window monitored by the
initiating device.
(11) An initiating device that is prevented from monitoring during its
intended transmit window due to monitoring system blocking from the
transmissions of a co-located (within one meter) transmitter of the same
system, may monitor the portions of the time and spectrum windows in which
they intend to receive over a period of at least 10 milliseconds. The
monitored time and spectrum window must total at least 50 percent of the 10
millisecond frame interval and the monitored spectrum must be within 1.25
MHz of the center frequency of channel(s) already occupied by that device or
co-located co-operating devices. If the access criteria is met for the
intended receive time and spectrum window under the above conditions, then
transmission in the intended transmit window by the initiating device may
commence.
(12) The provisions of (c)(10) or (c)(11) of this section shall not be used
to extend the range of spectrum occupied over space or time for the purpose
of denying fair access to spectrum to other devices.
(d) Emissions outside the band shall be attenuated below a reference power
of 112 milliwatts as follows: 30 dB between the band and 1.25 MHz above or
below the band; 50 dB between 1.25 and 2.5 MHz above or below the band; and
60 dB at 2.5 MHz or greater above or below the band. Emissions inside the
band must comply with the following emission mask: In the bands between 1B
and 2B measured from the center of the emission bandwidth the total power
emitted by the device shall be at least 30 dB below the transmit power
permitted for that device; in the bands between 2B and 3B measured from the
center of the emission bandwidth the total power emitted by an intentional
radiator shall be at least 50 dB below the transmit power permitted for that
radiator; in the bands between 3B and the band edge the total power emitted
by an intentional radiator in the measurement bandwidth shall be at least 60
dB below the transmit power permitted for that radiator. B” is defined as
the emission bandwidth of the device in hertz. Compliance with the emission
limits is based on the use of measurement instrumentation employing peak
detector function with an instrument resolution bandwidth approximately
equal to 1.0 percent of the emission bandwidth of the device under
measurement.
(e) The frame period (a set of consecutive time slots in which the position
of each time slot can be identified by reference to a synchronizing source)
of an intentional radiator operating in this band shall be 20 milliseconds
or 10 milliseconds/X where X is a positive whole number. Each device that
implements time division for the purposes of maintaining a duplex connection
on a given frequency carrier shall maintain a frame repetition rate with a
frequency stability of at least 50 parts per million (ppm). Each device
which further divides access in time in order to support multiple
communication links on a given frequency carrier shall maintain a frame
repetition rate with a frequency stability of at least 10 ppm. The jitter
(time-related, abrupt, spurious variations in the duration of the frame
interval) introduced at the two ends of such a communication link shall not
exceed 25 microseconds for any two consecutive transmissions. Transmissions
shall be continuous in every time and spectrum window during the frame
period defined for the device.
(f) The frequency stability of the carrier frequency of the intentional
radiator shall be maintained within ±10 ppm over 1 hour or the interval
between channel access monitoring, whichever is shorter. The frequency
stability shall be maintained over a temperature variation of −20° to + 50
°C at normal supply voltage, and over a variation in the primary supply
voltage of 85 percent to 115 percent of the rated supply voltage at a
temperature of 20 °C. For equipment that is capable only of operating from a
battery, the frequency stability tests shall be performed using a new
battery without any further requirement to vary supply voltage.
[ 58 FR 59180 , Nov. 8, 1993; 59 FR 15269 , Mar. 31, 1994. Redesignated at 59 FR 32852 , June 24, 1994, as amended at 59 FR 32853 , June 24, 1994; 59 FR 40835 , Aug. 10, 1994; 59 FR 55373 , Nov. 7, 1994; 60 FR 3303 , Jan. 13, 1995;
69 FR 62621 , Oct. 27, 2004; 77 FR 43013 , July 23, 2012]
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Subpart E—Unlicensed National Information Infrastructure Devices
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Goto Section: 15.321 | 15.401
Goto Year: 2014 |
2016
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