Specifications
ETSI
Final draft ETSI EN 300 328 V1.8.1 (2012
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3) The total time during which an equipment has transmissions on a given channel without re-evaluating the
availability of that channel, is defined as the Channel Occupancy Time.
4) The Channel Occupancy Time shall be less than 40 ms. Each such transmission sequence shall be followed with
an Idle Period (no transmissions) of minimum 5 % of the Channel Occupancy Time with a minimum of 100 µs.
After this, the procedure as in step 1 needs to be repeated.
5) The detection threshold shall be proportional to the transmit power of the transmitter: for a 20 dBm e.i.r.p.
transmitter the detection threshold level (TL) shall be equal or lower than -70 dBm/MHz at the input to the
receiver (assuming a 0 dBi receive antenna). For power levels below 20 dBm e.i.r.p., the detection threshold level
may be relaxed to TL = -70 dBm/MHz + 20 - Pout e.i.r.p. (Pout in dBm).
4.3.2.5.1.3 Conformance
The conformance tests for this requirement are defined in clause 5.3.7 and more specifically in clause 5.3.7.2.1.2.
4.3.2.5.2 LBT based Detect and Avoid
4.3.2.5.2.1 Definition
LBT based Detect and Avoid is a mechanism by which equipment using wide band modulations other than FHSS,
avoids transmissions in a channel in the presence of other transmissions in that channel.
4.3.2.5.2.2 Requirements & Limits
The present document defines 2 types of adaptive equipment using wide band modulations other than FHSS and that
uses an LBT based Detect and Avoid mechanism: Frame Based Equipment and Load Based Equipment.
Adaptive equipment which is capable of operating as either Load Based Equipment or as Frame Based Equipment is
allowed to switch dynamically between these types of operation.
4.3.2.5.2.2.1 Frame Based Equipment
Frame Based Equipment shall comply with the following requirements:
1) Before transmission, the equipment shall perform a Clear Channel Assessment (CCA) check using energy detect.
The equipment shall observe the operating channel for the duration of the CCA observation time which shall be
not less than 20 µs. The channel shall be considered occupied if the energy level in the channel exceeds the
threshold given in step 5) below. If the equipment finds the channel to be clear, it may transmit immediately.
The CCA time used by the equipment shall be declared by the supplier.
Figure 2: Example of timing for Frame Based Equipment