The following real-world example illustrates the benefits of ACM. Consider a CFIP link operating
at 23 GHz with 56 MHz channel spacing and 45.9 dBi (120 cm) antenna gain. The link is operating in a
moderate rain region similar to central Europe with a distance of 15 kilometers.
The system operation is set to a minimal payload of 69 Mbps Ethernet for 99.995% availability.
Most of the time system would support 363Mbps Ethernet connection instead of a 69 Mbps
connection. The system automatically monitors the link conditions and changes the capacity without
interrupting the data transmission (hitless changes), as shown in
Figure 4.6
.
Figure 4.6
Link availability and classes of services
In comparison similar system using 256QAM and providing similar capacity would provide only
99,687% of availability. Besides, lack of ACM would not provide higher availability. You would have to
decrease the distance, decrease modulation or increase antenna sizes to achieve 99,995% availability
for the given link.
This example demonstrates how the new technology, based on an ACM mechanism, can play a
key role in the development of cost-effective next-generation wireless access networks, by taking
advantage of traffic evolution from synchronous TDM traffic to packet IP-based traffic.
The
FEC
mode (Weak or Strong) allows increasing overall capacity of the link in terms of
deteriorating RSL sensitivity threshold.
For more details refer to table in Chapter 1.5.
4.2.2
Loopback Configuration
Loopback tests are accessible using local or remote management methods.
For safety purposes all loopbacks (local and remote) can be set on a fixed time interval only. If no
time interval is specified, the default value is 60 seconds (1 minute).
Figure 4.7
Loopback modes
CFIP PhoeniX Series TDM/IP Split Mount System Technical Description and Configuration Guide
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Rev. 1.13
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© SAF Tehnika JSC 2015
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