4RF Aprisa SR+, User Manual

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Managing the Radio | 143
Aprisa SR+ User Manual 1.11.1
Listen Before Send
with
Acknowledgement Channel access scheme where network elements listen to ensure the
channel is clear, before trying to access the channel. This mode is
optimized for low load networks and repeated networks.
With Acknowledgement, unicast requests from the remote radio are
acknowledged by the base station to ensure that the transmission
has been successful. If the remote radio does not receive an
acknowledgement, then random back-offs are used to reschedule
the next transmission.
Enabling acknowledgments increases reliability of transport but
reduces available channel capacity so if application has the
capability to handle lost or duplicate messages, the Access Scheme
should be set to Listen Before Send without Acknowledgement.
Point To Point (Half
Duplex) Channel access scheme for Point-to-point links using half duplex
radios. This is the preferred access scheme for mirrored bits ®.
The default setting is Access Request.
Maximum Packet Size (Bytes)
This parameter sets the maximum over-the-air packet size in bytes. A smaller maximum Packet Size is
beneficial when many remote radios or repeater stations are trying to access the channel, and smaller high
priority packets must not be delayed by larger low priority packets sent by other radios. The default setting
is 1550 bytes.
This packet size includes the wireless protocol header and security payload (0 to 16 bytes). The length of
the security header depends on the level of security selected.
When the security setting is 0, the maximum user data transfer over-the-air is 1516 bytes.
When encryption is enabled, the entire packet of user data (payload) is encrypted. If authentication is being
used, the security frame will be added (up to 16 bytes). The wireless protocol header is then added which
is proprietary to the Aprisa SR+. This is not encrypted.