User's Manual

Confidential
LTE eNB System Description v2.0 48
Copyright © 2017, All Rights Reserved.
Chapter 4 Message Flow
Data Traffic Flow
Sending Path
The user data received from EPC passes through the network interface module and
is transmitted through Ethernet switch to CDU. The transmitted user data goes
through baseband-level digital processing before being configured for CPRI, and
then E/O converted. The converted signal is transmitted through the optic cable to
the remote RRH. The RRH performs O/E conversion for a received optic signal.
The converted baseband signal from the wideband is converted into an analog
signal and transmitted through the high-power amplifier, filter, and antenna.
Receiving Path
The RF signal received by the antenna goes through RRH filter and low-noise
amplification by the LNA.
The RF down-conversion and digital conversion are performed for this signal, and
the signal is then converted to a baseband signal. It is configured for CPRI, and
goes through the E-O conversion again.
The converted signal is transmitted through optic cable to the CDU. The data for
which the SC-FDMA signal processing is carried out in the CDU is converted to
the Gigabit Ethernet frame and transmitted from the CDU to EPC via the GE/FE.
Figure 24. Data Traffic Flow
EPC
GE/FE
Main
Processor
Channel
Card
CPRI
conversion
E/O
O/E
RRH
O/E
E/O
DDC/
DUC
A/D
D/A
UP/
Down
DDC/
DUC
A/D
D/A
UP/
Down
BPF
BPF
CDU
CPRI
conversion
Optic
CPRI
PA
LNA
PA
LNA