Huawei

1. Hardware Structure of the BTS3900 (-48 V)
The BTS3900 cabinet that uses -48 V DC power contains the WRFU, MRFU, FAN unit, BBU, and
DCDU. In addition, 2 U space is available in the cabinet for installing the user equipment.
The BTS3900 cabinet (-48 V) supports the 3RFU typical configuration and the 6RFU full
configuration, as shown in Figure 1 and Figure 2 respectively. The SLPU is optional.
Figure 1 BTS3900 cabinet (-48 V) in typical configuration
Figure 2 BTS3900 cabinet (-48 V) in full configuration
BBU3900 Equipment
This describes the BBU3900 equipment. It is a baseband unit that implements communication
between the NodeB and the RNC.
The BBU3900 has the following functions:
• Providing ports for data communication between the NodeB and the RNC

2. • Providing the CPRI interface for communication between the BBU and the RRU
or the RFU
• Providing USB ports, one of which facilitates NodeB upgraded when a USB disk
is inserted during software installation and data configuration
• Providing OM channels between the BBU and the LMT or the M2000 to operate
and maintain the BBU
• Processing uplink and downlink baseband signals
• Managing the entire NodeB system in terms of OM and signaling processing
• Providing the system clock
Logical Structure of the BBU3900
The BBU3900, which features a modular design, consists of the transport subsystem, baseband
subsystem, control subsystem, and power module.
Figure 1 shows the logical structure of the BBU3900.
Figure 1 Logical structure of the BBU3900
Transport Subsystem
The transport subsystem has the following functions:
• Providing physical ports for data communication between the NodeB and the RNC
• Providing OM channels between the BBU3900 and the OMC (LMT or M2000) for
operation and maintenance

3. Baseband Subsystem
The baseband subsystem processes uplink and downlink baseband data. The functions of the
baseband subsystem are performed by the following modules:
• Uplink baseband data processing module: Consists of the demodulation unit and the
decoding unit. In this module, uplink baseband data is processed into despreading soft
decision symbols after access channel searching, access channel demodulation, and
dedicated channel demodulation. The symbols are then sent to the RNC through the
transport subsystem after decoding and Frame Protocol (FP) processing.
• Downlink baseband data processing module: Consists of the modulation unit and the
coding unit. The module receives the service data from the transport subsystem and sends
the service data to the FP processor for FP processing. The signals are finally sent to the
interface module after encoding, transport channel mapping, physical channel generating,
framing, spreading, modulation, and power control combination.
In the baseband subsystem, the BBU3900 has an integrated CPRI interface module that
connects the BBU3900 to the RRU.
Control Subsystem
The control subsystem manages the entire NodeB. The subsystem performs OM, processes
signaling, and provides the system clock.
• The OM module has functions such as equipment management, configuration
management, alarm management, software management, and commissioning
management.
• The signaling processor has functions such as NodeB Application Part (NBAP) signaling
processing, Access Link Control Application Part (ALCAP) processing, Stream Control
Transmission Protocol (SCTP) processing, and logical resource management.
• The clock module has functions such as providing a phase-locked line clock extracted
from the Iub interface (the clock is extracted from an E1, optical port, or FE), a GPS clock,
or an external clock. The BBU3900 extracts the clock from the Iub interface and then
provides a system clock for the NodeB after frequency dividing, phase locking, and phase
adjusting.
Power Module
The power module converts -48 V or +24 V DC power into the power required by the boards and
provides a port to connect to an external monitoring device.
Ports on the BBU3900
This describes the ports on the mandatory and optional boards of the BBU3900.
Ports on the Mandatory Boards of the BBU3900
Board Port Connector Quantity Description
WMPT E1 port DB26 1 One port supports
four E1s.
FE electrical port RJ45 1 -

4. Board Port Connector Quantity Description
FE optical port SFP 1 -
USB port for
loading
USB 1 Port for software
loading
USB port for test USB 1 Port for test
Commissioning
port
RJ45 1 Port for local
maintenance of
the NodeB
GPS port SMA 1 -
WBBP CPRI SFP 3 -
UPEU PWR 3V3 1 Port for leading in
-48 V DC or +24 V
DC power
MON0 RJ45 1 Providing two
RS485 monitoring
ports and
connecting to
external
monitoring devices
MON1 RJ45 1
EXT-ALM0 RJ45 1 Providing eight dry
contact alarm
inputs and
connecting to
external alarm
devices
EXT-ALM1 port RJ45 1
Ports on the Optional Boards of the BBU3900
Board Port Connector Quantity Description
UELP INSIDE DB25 1 Port for four E1/T1
inputs
OUTSIDE DB26 1 Port for four E1/T1
outputs
UFLP FE0 and FE1
(INSIDE)
RJ45 2 Connecting to
either the WMPT
or UTRP
FE0 and FE1
(OUTSIDE)
RJ45 2 Connecting to
external devices.

5. Board Port Connector Quantity Description
The FE0
(OUTSIDE)
connects to the
FE0 (INSIDE) and
the FE1
(OUTSIDE)
connects to the
FE1 (INSIDE).
USCU RGPS port DB8 3 Connecting to the
RGPS signal cable
BITS port SMA 1 Connecting to the
BITS clock
Clock test port SMA 1 Port for testing
clock signal output
Antenna port for
the satellite card
SMA 1 RF signal input
terminal of the
satellite card
UTRP E1/T1 port DB26 2 Providing eight
ATM over E1s or
eight IP over E1s
STM-1/OC-3 port SFP 1 Providing one
unchannelized
STM-1/OC-3
UEIU MON RJ45 1 Connecting to
external
monitoring devicesMON1 port RJ45 1
EXT-ALM0 port RJ45 1 Connecting to
external alarm
devicesEXT-ALM1 RJ45 1
Logical Structure of the WRFU/MRFU
The WRFU/MRFU, which features a modular design, consists of the interface module, transceiver
(TRX), Power Amplifier (PA), filter, and Low Noise Amplifier (LNA).
Figure 1 shows the logical structure of the WRFU/MRFU.

6. Figure 1 Logical structure of the WRFU/MRFU
Interface Module
The functions of the interface module are as follows:
• Receiving downlink baseband data from the BBU
• Transmitting uplink baseband data to the BBU
• Forwarding the data sent from the cascaded WRFUs/MRFUs
TRX
The TRX provides two RX channels and one TX channel for RF signals.
• The RX channels perform the following functions:
 Down-conversion of the received signals to IF signals
 Amplification of the IF signals
 Analog-to-digital conversion
 Digital down-conversion
 Matched filtering
 Digital Automatic Gain Control (DAGC)
• The TX channel performs the following functions:
 Shaping and filtering of downlink spread spectrum signals
 Digital-to-analog conversion
 Up-conversion of the IF signals to the TX band
PA
The PA adopts the DPD and A-Doherty technologies to amplify low-power RF signals from the
TRX.

7. Filter
The filters consist of a duplex filter and an RX filter. The filters perform the following functions:
• The duplex filter multiplexes one RX and one TX signals over RF channels so that they
can share one antenna channel. In addition, it filters RX and TX signals.
• The RX filter filters one RX signal.
LNA
The LNA amplifies the signals received from the antenna system.
Ports on the WRFU/MRFU
The external ports of the WRFU/MRFU are located at the bottom of the module and in the cabling
cavity.
The ports on the WRFU/MRFU are the power port, transmission ports, RF ports, and
commissioning port.
Table 1 Ports on the WRFU/MRFU
Port Type Connector
Type
Quantity Remarks
-48 V DC power input port 3V3 1 Power port
CPRI port SFP female 2 Transmission port for BBU
cascading
Interconnection port for receiving
RF signals
QMA female 2 Transmission port for
WRFU/MRFU cascading
Port for transceiving antenna
signals
DIN 2 RF port
Commissioning port RJ45 1 Reserved for fan monitoring
Functions of the WRFU/MRFU
The WRFU is the WCDMA RF filter unit, and the MRFU is the multi-carrier RF filter unit.
The WRFU/MRFU performs the following functions:
• The WRFU/MRFU, which adopts the direct frequency conversion technology,
modulates the baseband signals to the WCDMA TX band. After filtering and
amplification, the baseband signals are transmitted to the antenna system through the
duplex filter.
• The WRFU/MRFU receives uplink RF signals from the antenna system and then
down-converts the received signals to IF signals. After amplification, analog-to-digital
conversion, digital down-conversion, matched filtering, automatic gain control (AGC),
the IF signals are sent to the BBU for further processing.

8. • Power control and Voltage Standing Wave Ratio (VSWR) detection
• Reverse power detection
• Frequency synthesis and loopback test
• Generation of the CPRI clock, recovery of the CPRI clock of lost synchronization,
and alarm detection