Anaren A110LR09x, User Manual

Page: 23 / 38

A110LR09x
– User’s Manual
Page 23 of 38
Release Date 10/31/11
Where an acknowledgement is required, the additional transmitter on-time shall be included and
declared by the integrator.
In a period of 1 hour, the duty cycle shall not exceed the spectrum access and mitigation
requirement values as given in Table 5. For frequency agile devices without LBT, the duty cycle
shall apply to the total transmission time as given in Table 5, or shall not exceed 0.1 % per
channel in a period of 1 hour.
2.5.2.1.2. LBT & AFA
Listen Before Talk (LBT) is used to share spectrum between SRD transceiver equipment with
similar power and bandwidth. In order to make maximum use of the available channels,
intelligent or polite equipment may use a Listen Before Talk (LBT) protocol with a preferred
option of Adaptive Frequency Agility (AFA). AFA is defined as the capability of an equipment to
dynamically change channel within its available frequencies for proper operation.
LBT (Listen Before Talk) functionality is built in the A110LR09X modules, and the approved
configurations are made to meet the LBT Threshold limits. However
, LBT timing parameters,
specific to the end product, have to be established through controlling software and
declared by the OEM integrator or end-product developer in the product user manual or
user guide.
A brief description and limits of these parameters are given as follows:

Minimum Transmitter off-time is the period where a specific transmitter shall remain
off after a transmission or a communication dialogue between units or a polling
sequence of other units on the same frequency. The minimum TX off-time has to be
greater than 100 ms .

LBT minimum listening time is the minimum time that the equipment listens for a
received signal at or above the LBT threshold level immediately prior to transmission to
determine whether the intended channel is available for use.
LBT minimum listening time, t
L
, has two parts: the fixed part, t
F
, and the pseudo random
part, t
PS
. t
L
= t
F
+ t
PS
. The fixed part of the minimum listening time is 5 ms. The pseudo
random part has to be randomly varied between 0 ms and 5 ms or more in equal steps
of 0.5 ms as the following:
o
If the channel is free from traffic at the beginning of the listen time, and remains
free throughout the fixed part of the listen time, then t
PS
is automatically set to
zero by the equipment itself
o
If the channel is occupied by traffic when the equipment either starts to listen or
during the listen period, then the listen time commences from the instant that the
intended channel is free. In this situation the total listen time t
L
shall comprise t
F
and the pseudo random part, t
PS
.
Algorithmic details and values have to be declared by the provider of the equipment.

Maximum dead time is the period between the end of the listening time and the start of
the transmission. The maximum dead time cannot exceed 5 ms .