Specifications

ETSI

Final draft ETSI EN 300 328 V1.8.1 (2012

04)

NOTE: For LBT based frequency hopping systems with a dwell time < 60 ms, the maximum Channel Occupancy

Time is limited by the dwell time.

4) 'Unavailable' channels may be removed from or may remain in the hopping sequence, but in any case:

• there shall be no transmissions on 'unavailable' channels;

• a minimum of 15 hopping frequencies shall always be maintained.

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).

4.3.1.6.1.3 Conformance

The conformance tests for this requirement are defined in clause 5.3.7 and more specifically in clause 5.3.7.2.1.1.

4.3.1.6.2 Adaptive Frequency Hopping using other forms of DAA (non-LBT based)

4.3.1.6.2.1 Definition

Adaptive Frequency Hopping using other forms of DAA is a mechanism different from LBT, by which a given hopping

frequency is made 'unavailable' because interference was reported after transmissions on that frequency.

4.3.1.6.2.2 Requirements & Limits

Adaptive Frequency Hopping equipment using non-LBT based DAA, shall comply with the following minimum set of

requirements:

1) During normal operation, the equipment shall evaluate the presence of a signal for each of its hopping frequencies.

If it is determined that a signal is present with a level above the detection threshold defined in step 5. the hopping

frequency shall be marked as 'unavailable'.

2) The frequency shall remain unavailable for a minimum time equal to 1 second or 5 times the actual number of

hopping frequencies multiplied with the Channel Occupancy Time whichever is the longest. There shall be no

transmissions during this period on this frequency. After this, the hopping frequency may be considered again as

an 'available' frequency.

3) The total time during which an equipment has transmissions on a given hopping frequency without re-evaluating

the availability of that frequency is defined as the Channel Occupancy Time.

The Channel Occupancy Time for a given hopping frequency shall be less than 40 ms. For equipment using a

dwell time > 40 ms that want to have other transmissions during the same hop (dwell time) an Idle Period (no

transmissions) of minimum 5 % of the Channel Occupancy Period with a minimum of 100 µs shall be

implemented. After this, the procedure as in step 1 need to be repeated before having new transmissions on this

hopping frequency during the same dwell time.

EXAMPLE: A system with a dwell time of 400 ms can have 6 transmission sequences of 60 ms each, separated

with an Idle Period of 3 ms.

NOTE: For non-LBT based frequency hopping systems with a dwell time < 40 ms, the maximum Channel

Occupancy Time may be non-contiguous, i.e. spread over a number of hopping sequences (equal to

40 msec divided by the dwell time [msec]).

4) 'Unavailable' channels may be removed from or may remain in the hopping sequence, but in any case:

• there shall be no transmissions on 'unavailable' channels;

• a minimum of 15 hopping frequencies shall always be maintained.