Ale 3G / Xdl Arq Functionality - R&S M3SR 4100 Series Operating Manual

M3SR Series 4100
ALE-3G / xDL ARQ Functionality
Instead of the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) mechanism of
the IPoA protocol, the ALE-3G uses its own ALE algorithm to establish logical links between
stations of an ALE-3G network. This automatic link establishment algorithm chooses the best
communication channel to the destination based on channel quality analysis (LQA). After the
establishment of a logical link between two stations, the initiator of the link has the first op-
portunity to transfer an IP packet with one of the xDL protocols over the channel to the des-
tination. HDL (High Data Rate Link Protocol) and LDL (Low Data Rate Link Protocol) always
guarantee the error-free transfer of the packet by using an ARQ mechanism.
Since the ALE-3G channel access differs from the IPoA protocol, the following features of
the IPoA protocol are not needed or supported:
FastLink Mode (FLM)
IPoA Rebro
Message Service Alert messages
IPoA operational mode
IPoA connection mode
Change of IP Air address
Multicast Routing
Operating Manual 6175.4760.02 – 01
Note
Not needed. ALE-3G establishes logical links by itself.
Not supported.
Not supported. xDL only supports Point-to-Point links.
Not supported.
Not supported.
Not supported. ALE-3G uses a static look-up table for
conversion of IP to ALE-3G address. This can only be
changed via configuration.
Not supported. xDL only supports Point-to-Point links.
IP over Air (IPoA)
5.41