User Manual

DXUDistribution Switch Unit
function is activated during the installation phase, using
the OMT.
CPU
The CPU has the following features:
• Resource management within the RBS
• RU software loading and storage
• Interface to the OMT
• Operation and maintenance
• Internal and external alarms
• Extraction of LAPD signalling information
CTU
The CTU generates stable reference pulses for the
TRUs.
HDLC
Concentrator
(LAPD
Concentration)
The HDLC concentrator has the following functions:
• Multiplexing (and demultiplexing) of up to four
LAPD signalling TSs into one TS and vice versa for
increased capacity of the PCM line
• Reading control channel information and distributing
it to the TRUs or the CPU part
LAPD multiplexing means that the A-bis LAPD signalling
links and traffic links are multiplexed on the same 64
kbit/s link. Only two PCM TSs per TRU are needed
which makes LAPD multiplexing useful for sites with a
small number of TRUs.
TG
Synchronization
The TGSync/External Synchronization Bus (ESB)
interface is used for timing and synchronization
between two or several RBSs. The ESB consists of
three signalling pairs.
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EN/LZT 720 0243 Uen R1A