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Chapter 4 Message Flow
LTE eNB System Description v2.0 49
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Network Sync Flow
The eNB uses GPS and IEEE1588v2 for synchronization. Clock module receives
synchronization signal from the GPS, creates and distributes clocks. For
IEEE1588v2, a processor receives IEEE1588v2 packet from backhaul, and
generate clock through PLL and clock module.
Supported PTP profiles are as below:
 IEEE1588v2 unicast negotiation mode (phase)
 IEEE1588v2 unicast negotiation mode (frequency)
 ITU-T G.8265.1 (frequency)
 ITU-T G.8275.1 (phase)
 ITU-T G.8275.2
Figure 25. Network Synchronization Flow
Clock
Generation & Distribution
Clock module
CDU
GPS
Control
SYS (System Clock 30.72 MHz)
SFN (System Frame Number)
PP2S (Even Clock)
Digital 10 MHz
PP2S (Even Clock)
Processor
IEEE1588v2
PLL
control
1PPS
Alarm Signal Flow
An environmental fault or hardware mount/dismount is reported with an alarm
signal, which is collected by LMD1 of the CDU, and reported to LTE System
Manager (LSM). The operator can also provide custom alarms through the UDA.
The following alarms are collected by the LMD1 of CDU:
Table 11. Alarms
Alarm Type
Description
Applicable