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M3SR Series 4100
4.4.1.6
Optimized Transfer of IP Packets
IP-based data transmission with the embedded xDL (x = L = Low or H = High, Data Rate
Link) data link protocol offers the following features:
Adaptive Selection of ARQ Protocols
The ALE-3G protocol can automatically select the best setting of the xDL ARQ protocol
based on measurements of the actual channel condition and the used packets size. This
adaptive selection will achieve a better throughput than the manual selection.
Priority-Based Session Management
To optimize throughput of peer-to-peer traffic in an ALE-3G network, an innovative algorithm
for managing xDL sessions can be used. This priority-based session management takes into
account the priority of the traffic and improves throughput and latency.
Packet Aggregation
Another way to improve the throughput of the xDL packet transfer is the aggregation of small-
er packets to a datagram of maximum 10 Kbytes.
4.4.1.7
Voice Priority over IP Data
'Voice Priority over IP data' (VPoIPD) enables the user to initiate a voice link while configured
for IP-data connections. As possible voice modes 'Analog Voice', 'Secure Digital Voice' or
'Last Ditch Voice' could be selected. If VPoIPD is disabled, there will be no reaction to any
voice PTT requested, but incoming voice calls are still processed. If VPoIPD is enabled, the
radio behaves as follows:
The request for the voice call may be made in two different states of the radio:
•
The radio is currently 'listening/scanning", the voice call can be initiated immediately.
•
The radio has established (or is establishing) an IP-data link. In this case this link will be
terminated automatically. Afterwards the radio will initiate the voice call.
After the voice link is disconnected (by user termination, or if the activity timeout is reached),
the radio will return to normal data operation: In case of available data a new call will be es-
tablished, or the radio will return to 'listening/scanning".
The radio will preserve the IP-data to transmit while a voice priority call is active. Even if there
is no data loss caused by the voice call, the data could still become obsolete by the time-to-
live information. Also the normal congestion handling is active.
Operating Manual 6175.4760.02 – 01
Automatic Link Establishment 3
rd
Generation (ALE-3G)
4.69
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