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User ManualM900/M1800 Base Transceiver Station (BTS30) Table of Contents
Huawei Technologies Proprietary
i
Table of Contents
Chapter 2 Hardware Architecture ................................................................................................ 2-1
2.1 Overview............................................................................................................................ 2-1
2.2 CDU Frame........................................................................................................................ 2-2
2.2.1 CDU......................................................................................................................... 2-2
2.2.2 ECDU ...................................................................................................................... 2-3
2.2.3 EDU......................................................................................................................... 2-3
2.2.4 RCDU ...................................................................................................................... 2-5
2.2.5 REDU ...................................................................................................................... 2-5
2.2.6 SCU......................................................................................................................... 2-5
2.2.7 ESCU ...................................................................................................................... 2-6
2.3 TRX Frame ........................................................................................................................ 2-6
2.3.1 TRX ......................................................................................................................... 2-6
2.3.2 PBU ....................................................................................................................... 2-11
2.4 Common Resource Frame .............................................................................................. 2-12
2.4.1 PSU ....................................................................................................................... 2-12
2.4.2 PMU ...................................................................................................................... 2-13
2.4.3 TMU....................................................................................................................... 2-14
2.4.4 TES ....................................................................................................................... 2-17
2.4.5 ASU board............................................................................................................. 2-19
2.4.6 ABB ....................................................................................................................... 2-20
2.4.7 ABA ....................................................................................................................... 2-21
2.5 Other Parts of the Cabinet ............................................................................................... 2-21
2.5.1 TDU ....................................................................................................................... 2-21
2.5.2 FMU....................................................................................................................... 2-27
2.5.3 Switch Box............................................................................................................. 2-27
2.5.4 Fan Box ................................................................................................................. 2-28
2.5.5 Air Box................................................................................................................... 2-28
2.6 Antenna and Feeder System........................................................................................... 2-28
2.6.1 Antenna................................................................................................................. 2-29
2.6.2 Feeder................................................................................................................... 2-30
2.6.3 Lightning Arrester.................................................................................................. 2-30
2.6.4 Tower-top Amplifier (Optional) .............................................................................. 2-31
2.7 Power Supply System...................................................................................................... 2-32
2.7.1 Overview ............................................................................................................... 2-32
2.7.2 Overall Structure ................................................................................................... 2-33
2.8 Environment Monitoring System...................................................................................... 2-35
2.8.1 Outlook of Environment Monitoring Instrument..................................................... 2-35
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2.8.2 Function Provided by Environment Monitoring Instrument ................................... 2-36
2.8.3 Environment Monitoring Instrument Inputs ........................................................... 2-36
2.8.4 Alarm Indicators .................................................................................................... 2-37
2.8.5 Executing Devices................................................................................................. 2-37
2.8.6 Communication ..................................................................................................... 2-38
2.9 Lightning Protection System............................................................................................ 2-38
2.9.1 Lightning Protection for DC Power Supply............................................................ 2-39
2.9.2 Lightning Protection for AC Power Supply............................................................ 2-40
2.9.3 Lightning Protection for Trunk Cables................................................................... 2-41
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Chapter 2 Hardware Architecture
2.1 Overview
A BTS30 cabinet mainly comprises a common resource frame, a TRX frame and a
CDU frame, which can be flexibly configured according to the user demands. There
are also some other elements like TDU, switch box, fan box, air box, etc.
The hardware architecture of the BTS30 cabinet is shown in Figure 2-1 .
CDU CDU CDU
SWITCH BOX
TX
RX
TRX
TX
RX
TRX
TX
RX
TRX
TX
RX
TRX
TX
RX
TRX
TX
RX
TRX
P
S
U
P
S
U
P
S
U
P
S
U
P
M
U
T
M
U
T
M
U
T
U
E
T
E
S
AIR BOX
FAN BOX
TDU
CDU: Combiner and Divider Unit TRX: Transceiver UnitPMU: Power Monitoring Unit TMU: Timing/Transmission and Management UnitPSU: Power Supply Unit TES: Transmission Extension Power Supply UnitTEU: Transmission Extension Unit TDU: Timing Distribution Unit
Figure 2-1Hardware architecture of the BTS30 cabinet
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2.2 CDU Frame
The CDU frame implements the combining of transmitted signals, dividing of
received signals and duplex functions. The frame can be configured with CDU,ECDU, EDU, RCDU, REDU, SCU or ESCU.
2.2.1 CDU
I. General
CDU combines and filters the transmitted signals, filters, amplifies and distributes
received signals. It also provides feed circuit for the tower-top amplifier through a
bias-T circuit.
Through bridge combing (broadband combing) used in BTS30, multiple TX and RX
signals can be multiplexed on a single antenna unit.
The 2 channels of transmitting signals are combined into 1 (2-into-1), while at the
receiving end signals from 1 of the 2 channels are divided into 4 (or 8 incase of only
one channel) channels.
CDU supports the P-GSM band (GSM900 and GSM1800), and the maximum input
power of its single port is 60 W.
II. Structure and function
The functional blocks of the CDU are shown in Figure 2-2 .
Test coupler Amp. feeder
Divider
Duplexer
LNA Rx filter
Alarm and control unit
Combiner Tx signal input
Rx signal output
Divider
Rx signal output
LNA
Amp. feeder
CDU
Figure 2-2Functional blocks of the CDU
Besides the combining and dividing functions, CDU also has the following alarm
detection functions:
VSWR (Voltage Standing Wave Ratio) monitoring: Monitoring the status of
antenna system. When the detected VSWR exceeds the threshold 1.5:1, the
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CDU reports minor alarm and the corresponding indicator on the panel is on.
When the VSWR exceeds the threshold 2.5:1, the CDU reports critical alarm,
the corresponding indicator on the panel is on, and signal transmission will stop
1 minute later.Low noise amplifier fault alarm: The fault signal is extracted from the power
supply current of the low noise amplifier. When the current exceeds a certain
level, alarm signals and indications are generated.
Tower-top amplifier alarm: When there is tower-top amplifier in service, the
CDU determines the operation status of the amplifier according to its working
current. If the current exceeds preset value or there is no current, alarm signal
will be generated.
Control functions: Remotely control the low noise amplifier attenuation
(dynamic control 15 levels, in steps of 1dB) both in the main receiving path and
diversity receiving path, supply/cut the feeder depends on whether tower-topamplifier is equipped, cut the feeder to the amplifier in case of alarm.
Note:
The input power of the CDU configured in BTS30 is 60W. When PBU is used, ECDU with large powershould be configured.
2.2.2 ECDU
The functions and external interfaces (including dimensions) of ECDU are the same
as that of CDU. It implements combination of transmitted signals, dividing of
received signals, and duplex functions. The difference is that the maximum power
input of the single port of ECDU reaches 100W.
2.2.3 EDU
I. General
EDU is a low-loss duplex and dividing unit aimed to solve the issue of wide
coverage. It can perform the duplex function for two TRXs, the filtering of
transmitted/received signals, low noise amplification, and dividing function. It also
provides feeder to the tower-top amplifier.
Each TRX uses its own antenna, so no combination of signals is needed. For
received signals, 1-to-2 dividing is employed.
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EDU supports the P-GSM band (GSM900 and GSM1800), and the maximum input
power of its single port is 60 W.
II. Structure and function
The functional blocks of the EDU are shown in Figure 2-3 .
EDUTest coupler Amp. feeder
Divider
Duplexer
LNA
Alarm and control unit
Tx signal input
Rx signal output
Divider Rx signal output
LNA
Amp. feeder Tx signal input Duplexer Test coupler
Figure 2-3Functional blocks of the EDU
Besides the combining and dividing functions, the EDU also provides the following
alarm detection functions:
1) VSWR (Voltage Standing Wave Ratio) monitoring: Monitoring the status of the
antenna system. When the VSWR exceeds the threshold 2.5:1, the EDU reports
alarm.
2) Low noise amplifier fault alarm: The status of the LNA can be determined based
on the power supply current. When the current exceeds a certain level, alarm
signals and indications are generated.
3) Tower-top amplifier alarm: When there is tower-top amplifier in service, EDU
determines the operation status of the amplifier according to the working current of
amplifier. If the current exceeds preset value or there is no current, alarm signal will
be generated.
4) Control functions: Remotely control the low noise amplifier attenuation (dynamic
control 15 levels, in steps of 1dB) both in the main receiving path and diversity
receiving path, supply/cut feeder depends on whether tower-top amplifier is
equipped, cut the feeder to the amplifier in case of alarm.
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2.2.4 RCDU
RCDU is the same as ECDU in structure, functions, peripheral interfaces, peripheral
interface dimension and maximum input power. It can also combine transmitted RFsignals, divide received RF signals and implement reception and transmission
duplex. The difference between RCDU and ECDU lies in the bands supported by
them. The band supported by RCDU ranges from 876 to 901 MHz (uplink) and 921
to 946 MHz (downlink). For the BTS working in the EGSM band with the frequency
range of 880-890 MHz (uplink) and 925-935 MHz (downlink), RCDU is optional.
2.2.5 REDU
REDU is the same as EDU in structure, functions, peripheral interfaces, peripheral
interface dimension and maximum input power. It can also implement 1-to-2 divisionof received signals and implement reception and transmission duplex. The
difference between REDU and EDU lies in the bands supported by them. The band
supported by REDU ranges from 876 to 901 MHz (uplink) and 921 to 946 MHz
(downlink). If the BTS works in the EGSM band with the frequency range as
880-890 MHz (uplink) and 925-935 MHz (downlink) and it is required to achieve low
loss, REDU is optional.
2.2.6 SCU
I. General
SCU combines the signals from 4 TRXs into 1 channel for transmission. It employs
the electric bridge with 3dB power loss to achieve the broadband combing. Used
together with CDU, it can achieve the combination of signals from multiple TRXs.
The introduction of SCU is to reduce the number of CDUs, hence saving costs.
SCU supports the PGSM band (GSM900 and GSM1800), and the maximum input
power of its single port 60 W.
II. Structure and function
The functional blocks of the SCU are shown in Figure 2-4 .
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SCU1
2
3
4
Combiner
Tx signal input
Combiner
Tx signal outputCombiner
Figure 2-4Functional blocks of the SCU
2.2.7 ESCU
ESCU is the same as SCU in structure, functions, peripheral interfaces and
peripheral interface dimension. It can also implement 4-in-1 combination of
transmitted signals. The differences between ESCU and SCU lie in:
Bands supported by them. The band supported by ESCU ranges from 921 to
960 MHz (900M ESCU) and 1805 to 1880 MHz (1800M ESCU).
Maximum input power supported by their single port. The single port of ESCU
supports the maximum input power of 100 W.
The 900M ESCU can be used with 900M CDU, ECDU, EDU, RCDU and REDU
while the 1800M ESCU can be used with 1800M CDU, ECDU and EDU. When
ESCU works with the cooperation of ECDU, it can implement more than four
carriers, which thus improves the BTS transmit power and effective radiated power
of antenna ports and enlarges the coverage of BTS.
2.3 TRX Frame
The TRX frame implements all the processing functions of the carrier, including
baseband processing, RF processing, power amplifier and power supply. The TRX
frame can be configured with the TRX and the PBU.
2.3.1 TRX
I. General
TRX is the key part of the BTS which receives various types of management and
configuration information issued by the TMU and reports its status and alarm
information to the TMU.
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The TRX separates the received information from the mobile stations through
demodulation and balancing into signaling and speech information, and transmits
them upward (i.e. to BSC and MSC). The downlink signaling and speech information
is sent to the CDU and the antenna after being processed by the TRX.TRX has two types: 40W TRX and 60W TRX.
II. Structure and functions
The structures of the two types of TRXs are mainly the same. Figure 2-5 shows the
structure of the 40W TRX. It includes the baseband signal processing unit and the
radio frequency signal processing unit.
SCP DSP CUITDP PAU
RCU
TBU RPU
DBUS FH_BUS
CBUS
TIMING_BUS
Clock processing part
Send
Main receiver Diversity receiver
SCP: Signaling Processing Unit DSP: Digital Signal Processing UnitCUI: Carrier Unit Interface PAU: Power Amplifier UnitRCU: Receiving Unit TDP: Transmitter Driver and PLL unitTBPU: TRX Baseband signal Processing Unit RPU: RF signal Processing UnitCBUS: Control Bus FH_BUS: Frequency Hopping BusDBUS: Data Bus
Figure 2-5Structure of the 40W TRX unit
1) Baseband signal processing unit
The baseband signal processing unit of 40W TRX is called TBPU (Transceiver
Baseband Process Unit), while that of 60W TRX is called HTBU (High Power TRX
Baseband Processing Unit). The unit consists mainly of the Signaling Processing
Unit (SCP), the Digital Signal Processing unit (DSP), and the Carrier Unit Interface
(CUI). As the GSM system is a time division multiplexing system, the operation of
the TRX relies on various clocks. So the TRX contains some clock processing
logical units.
Signaling processing unit (SCP)
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The SCP processes signaling protocols on different BTS interfaces, including the
layer 2 protocol LAPDm with the mobile station (MS), the layer 2 protocol LAPD with
the BSC interface, and the layer 2 protocol (DCL) with the operation & maintenance
module (OMU), as well as layer 3 non-transparent messages.The SCP also handles DSP program loading and alarm processing of the whole
TRX module.
Digital signal processing unit (DSP)
The DSP performs such functions as signal encoding/decoding, signal demodulation,
interleaving and de-interleaving, and speech/data communication with the TRAU.
It sends the signaling received from the MS to the SCP, receives signaling sent from
the SCP, and performs corresponding encoding/decoding according to related
protocols. It sends the downlink data via the CUI to the carrier unit RPU.
Carrier unit interface (CUI)
The CUI is the interface between the DSP and the RPU. It supports baseband
hopping, and according to system configuration can work in either hopping or
non-hopping mode (when the system works in the RF hopping mode, the hopping
interface works in non-hopping mode and the hopping functions are completed by
the carrier unit).
The CUI samples and filters the uplink intermediate frequency signals sent from the
RPU, and sends them to the DSP for demodulation and combination.
Clock processing part
T he TRX extracts clocks sent from the TMU over the clock buses. To ensure the
reliability, the clock buses work in active/standby mode. These clocks include the
frame clock, the octet bit clock, and the frame number.
The clock processing part in the TRX first chooses either the active clock or the
standby clock, then makes frequency division calculation and generates the timeslot
number and bit clocks required by the local TRX.
2) Radio frequency signal processing unit (RPU)
The RPU consists of 3 parts: Receiving Unit (RCU), Transmitter Driver and PLL unit
(TDP), and Power Amplification Unit (PAU).
Receiving unit (RCU)
The RCU provides diversity reception functions, that is, the receiver consists of two
completely independent channels, and the input signals come from the main
antenna and diversity antenna. In complicated radio transmission areas where one
antenna receives very poor signal, the signal received from the other (diversity)
antenna may be of a better quality.
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frequency conversion, then sends them to the receiver after coupling. It is used to
check the TRX transmit channel and the receive channel.
Power amplifier unit (PAU)
The PAU mainly performs radio signal amplification. The standard output power of
40W 900M TRX, 40W 1800M TRX and 60W TRX is respectively 46.0dBm, 45.5dBm
and 47.3dBm. It also provides feed sampling signals controlled by the transmitter
APC, and the following alarm information:
Over-temperature alarm, when the temperature of the power amplifier exceeds
85 C, the power amplifier unit reports the high-temperature alarm via the
baseband unit, and automatically turns off the power amplifier.
Over standing wave alarm, when the standing wave at the power amplifier
output end exceeds 3.5, it reports standing wave alarm to the baseband unit.
III. Interface
External interfaces of the TRX module includes:
CBUS2: the interface between the TRX and the TMU. The TMU performs
management and maintenance on the TRX module through the CBUS.
DBUS1, DBUS2: the switching functions of TMU switch the DBUS of the TRX to the
Abis interface. The uplink and downlink signaling processed by the SCP and the
uplink and downlink speech data processed by the DSP are all transmitted through
the DBUS.
TIMING_BUS: it receives the frame clock and 1/8-bit clock as well as frame number
of the TDU, and obtains the various clock signals required by the TBU board
through the clock unit interface.
FH_BUS: used to transmit hopping data between TRX modules when the BTS is in
the baseband hopping mode.
Radio interface: the TRX radio interface has 1 transmit terminal and 2 receive
terminals. The function of the 2 receive terminals is the main reception and diversity
reception. The TRX radio interfaces are connected to the CDU.
Panel display: on the panel, there are 4 LED indicators, from top to bottom they are
power supply indicator, SCP running indicator, DSP running indicator, and fault
indicator.
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2.3.2 PBU
I. General
The Power Booster Unit (PBU) is a kind of TRX output power amplifier aimed to
solve the problem of wide coverage. It can enhance the Effective Radiation Power
(ERP) of the antenna and enlarge the coverage area of a BTS. The maximum
output power of the PBU reaches 49 1dBm.
The PBU comprises the power synthesizer module, the alarm management module
and the power supply module. It can amplify the output power of 1 TRX.
II. Structure and functions
The functional blocks of the PBU are shown in Figure 2-6 .
Input coupling & delay filtering
Amp. & phase control 60W power amplify
Power Synthesizer Module
Alarm collect & outputControl signal generation
Alarm Management Module
26V
26V
8V
8V
Alarm collectionPower amplify control
Alarm output
26V
TRXpoweroutput
PBU
CoupleOutput
PBUpower output
P o w e r m o d u l e
P o w e r s y n t
h e s i z e
a n d
d e t e c t
Figure 2-6Functional blocks of PBU
The PBU couples the 40W power signals output from the TRX into main channel
signals and coupled channel signals. The main channel signals, after delay filtering,
enter the power synthesizer unit. The coupled channel signals are amplified into
60W signals before being sent to the power synthesizer unit. To obtain final
combined signals, amplitude and phase control will be conducted on the 2 channels
of input signals.
The generation of control signals and the collecting/reporting of alarms are
completed by the alarm management module. While the coupling, controlling and
synthesizing of power signals are performed by the power synthesizer module.
1) Power synthesizer module
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Under the control of alarm management module, the power synthesizer module
amplifies TRX output signals, and at the same time provides power control and
alarm information, and alarm signals to the alarm management module, which
detects power amplification functionality and reports alarms.2) Alarm management module
The alarm management module receives from the power synthesizer module the
power control and alarm information, and alarm signals. It is responsible for the
detection of power amplification functionality and the control over amplitude and
phase. It also reports relevant alarms.
3) Power supply module
The power supply module supplies power to the power synthesizer module and the
alarm management module.
2.4 Common Resource Frame
The common resource frame is the most import part of the cabinet. It includes 14
slots. Except for slots No.8 and No.9 which are reserved, other slots are respectively
configured (from left to right) with PSUs (6 slots), PMU, TMU, TES and TEU.
Configurations of the TES and the TEU are optional.
2.4.1 PSU
PSU is a built in power supply module.
Depending on the power supply mode, BTS30 uses the power supply module of
different models. When 220VAC is adopted, the BTS uses the power supply module
with 220VAC input and +26VDC output. When +48VDC is adopted, it uses the
module with +48VDC input and +26VDC output. When +24VDC is used, no power
supply module is needed.
One PCU can supply power to two TRXs (or PBUs) in N+1 flow-equalization
hot-standby mode. The working current of the module is 25A.
Note:
For detailed descriptions, please refer to section 2.7 Power Supply System.
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2.4.2 PMU
I. General
PMU (Power Monitoring Unit) is close to the power supply module, managing the
power supply of the module. There are two types of PMUs: PMU for the DC/DC
module and PMU for the AC/DC module. The main difference between these two is
the battery management function. To reduce work load, both the AC/DC module and
the DC/DC module share one monitoring board.
II. Functions
Following describes the AC/DC module monitoring board.
1) ControlSwitch on/off of the power module (remote control available), with an output
signal of 12V/10mA
Floating/equalizing charge of battery and current limit control
Connect/disconnect control of battery protection load, with a 230.5V output
low-voltage alarm, loading power-on/off condition
2) Switch signals
AC mains on/off signal and high-/low-voltage signal (12V/10mA)
Four fault status parameters (12V/10mA) provided to the monitoring board by 4
AC/DC modules
Fan monitoring status parameters (normally, 12V/10mA)
Fuse on/off status parameters of external battery (-0.3V
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Fan PMU
AC power supply
AC/DC AC/DC ... AC/DC
Fuse
Battery
L o a d
Figure 2-7Illustration of the PMU monitoring
2.4.3 TMU
I. General
TMU is located in the common frame of the BTS30. It is the timing, transmission and
management function entity of BTS30. It has the following main functions:
Provides channel multiplexing and flexible networking modes (including star-,
tree-, and chain- connections).
Provides Man-Machine Interfaces (MMI) and operation & maintenance links for
software loading, fault management, configuration management, performance
management and security management, etc.
Provides centralized BTS clock and its management, and clock hot standby
function.
Provides alarm signal input ports, and handles external alarm collection and
control.
Two TMUs can be configured in the basic cabinet, providing clock source in hotstandby mode and serving to increase the number of E1 interfaces (each TMU
provides 4 E1 interfaces). In combined cabinet configurations, TMU boards are
configured in the basic cabinet only.
II. Structure and working principle
The functional blocks of the TMU are shown in Figure 2-8 .
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MCK
OMU
BIU
EAC
DBUS
CBUSMMI
BSC
MCK
Act ive TMU
Environment Monitors
Abis
TDU
Standby TMU
BIU
TBUS
Maintenance Terminal
RS485
External clock
BSC: Base Station Control TMU: Timing/Transmission and Management UnitBIU: Base Station Interface Unit OMU: Operation and Maintenance UnitEAC: External Alarm Collector MCK: Main Clock moduleTBUS: Timing Bus DBUS Data BusCBUS: Control Bus TDU: Timing Distribution Unit
Figure 2-8Functional blocks of the TMU
1) Base station interface unit (BIU)
The BIU handles conversion and reconversion between digital signals of the BTS
internal HWs and the HDB3 codes (on E1 lines). It switches timeslots on HW toachieve flexible timeslot configuration, extracts superior clock signals, supports
external clock input, and outputs accurate clock signals through phase locking and
frequency division. It synchronizes internal bus data transmission, or generates
free-run clock signals when superior clocks are not available (due to E1 line or BSC
fault) to synchronize internal bus data transmission, and generates alarm and
reports them to OMU.
One BIU module can support a maximum of 4 E1 lines. The BIU modules on the two
TMU boards in one cabinet can be mutually extended, and the data on the 8
mutually extended E1 lines can be freely switched. The E1 interfaces on the BIUmodule can be respectively connected to the BSC or to the higher/lower level BTS
to complete star, tree, and chain connections.
2) Operation and maintenance unit (OMU)
The OMU module is the core control and processing center of the TMU. Through the
OMU, performance parameters of various BIU and MCK units can be directly
configured.
The OMU receives fault alarms, handles fault management, and communicates via
internal control buses with the CPU of various units (TRX, CDU, PMU, TES, etc.) in
the BTS, so as to complete the operation and maintenance of the whole system.
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It collectively loads and saves the software of various BTS units before loading
software for each unit according to demands. Moreover, it supports the
Man-Machine Interface (MMI) connecting to the PC.
The Flash memory of the OMU module can store two different versions of BTSsoftware. One is the software currently used by the BTS and the other one is the
previous BTS software. It can load either version according to the requirements to
each board.
When the software on the BTS needs to be upgraded, the new version can be
loaded from the BSC through OML and saved on the OMU to replace the old
version. Meanwhile, the OMU keeps the original software version of the BTS as a
backup, in case the loading should fail.
3) Main clock module (MCK)
The MCK is configured with an OCXO (oven controlled crystal oscillator) compliant
with the stratum 3 A standard, and phase-locking and frequency-division circuits.
According to system configuration, the MCK can work in the free-run mode or
software phase-locked mode to output a reference clock SREF with a stability better
than 5x10 -8. Moreover, it can provide the frame clock FCLK used by radio interfaces,
the octet bit clock OBCLK, and the frame number (FN).
The clock source of a synchronous cell is provided by the MCKs on the two TMU
boards in the basic cabinet of the basic cabinet group. The MCK modules on the two
boards work in hot standby mode. Switchover is made automatically in case ofactive board failure, which will be reported to the OMU.
4) External alarm collector (EAC)
The EAC collects the alarm signals from environment monitors, including 8 inputs of
digital signals for fire, smog, (high/low) temperature, humidity, water, BTS room door
control (open/closed), cabinet door control (open/closed), and air-conditioning
alarms. For expansion, the EAC also reserves 16 input channels for digital signals, 8
input channels for analog signals and 8 output channels for digital signals. The
collected alarm signals are reported to the OMU.
III. Interfaces
Abis interface: One TMU provides 4 E1 interfaces. two TMU boards can provide up
to 8 E1 interfaces for connection with the BSC or other BTS (corresponding to
different configuration modes of the BTS).
Internal data bus DBUS: provides two 32-timeslot TDMA buses (i.e. DBUS1 and
DBUS2) and corresponding clock signals, connecting the TRXs of one cabinet
group, and transmitting traffic and signaling data of TRXs. When there are less than
10 TRXs in one cabinet group, 2 buses can work in the active/standby mode.
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Internal control bus CBUS: The communication between TMUs is implemented
through CBUS1, and that between TMU and TRX is implemented through CBUS2.
CBUS3 is responsible for the communication between TMU and low-rate control
parts like CDU, PMU and TES, and between TMU and external monitors. For details,refer to Figure 2-8.
Internal clock bus TIMING_BUS: provides clocks (frame synchronization clock
FCLK, octet bit clock OBCLK) and frame No. (FN) required by radio interfaces for all
TRXs in the synchronous cell, and the highly accurate reference clock SREF for the
radio frequency processing unit.
Alarm input interface EAC: provides 24 digital signal inputs, 8 analog signal inputs
and 8 digital signal outputs. Among them, the 8 digital signal inputs are external
environment alarm inputs, while the remaining 16 digital signal inputs, 8 analog
signal inputs and 8 digital signal outputs are reserved for user extension.
Man machine interface: a standard asynchronous serial port or network port, it
completes the communication with PC, enabling the operation personnel to perform
various operations locally.
External synchronization clock interface: inputs highly accurate 2MHz clock
compliant with G.703 wave forms, which is used as the frequency reference of E1
and system data buses.
2.4.4 TES
TES provides TEU with various types of working power supplies and handles
communication transfer. It provides +5V and -5V power and ringing current, so that
TEU board can work normally to perform transmission network functions, thus
realizing base station built-in transmission.
TES can communicate with TEU and TMU to achieve information reporting from
TEU to TMU.
I. Functions
The TES board has the main functions as follows:
Provides the transmission board with DC power supply, including +5V and -5V.
Achieves the communication between TMU and TEU.
Provides transmission board with ring current, the ringing current signal is the
75V/25Hz sine wave AC signals.
II. Structure
The structure of the TES unit is shown in Figure 2-9 .
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Communicationmodule
Power supply
module
+26V input1st +5V output
Ringing current output-5V output
To the 1st TEU
To the 2nd TEU
To two TEUs simultaneously
To TEU communication serial port
To TMU communication serial port
2nd +5V output
To two TEUs simultaneously
Figure 2-9TES structure
Power supply module
The power supply module of the TES board includes two parts, the DC/DC
conversion circuit and the DC/AC conversion circuit. The DC/DC conversion circuit
converts two +24V DC supplies into +5V DC and one +24V DC supply into 5V DC.
The DC/AC conversion circuit converts +24V DC into 75V AC ringing current.
The ringing current module is featured by high performance ringing current signal
sources, sine wave output, low distortion, light weight, and high power density. Its
output voltage is 75V AC, and its output current is 40mA, with a standard tone of
25Hz.
Note:
Figure 2-9 shows that TES can provide power for 2 TEU boards.
Communication module
The main function of the communication module is to handle the communication
between TES and TMU, between TES and TEU, and to acquire the PCB version No.
and cabinet No. of the TES board.
The serial port communication between TES and TMU is implemented through
RS485 standard. TES is connected with CBUS3 via the level conversion circuit. The
serial port communication between TES and TEU adopts the point-to-point mode,
with the serial port level as the TTL level.
Communication with TMU mainly includes reporting transmission network
information and transmission board information from TEU to TMU, as well as
reporting TES board status information to TMU.
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Communication with TEU is mainly to acquire transmission network and base
station transmission board information.
2.4.5 ASU board
Due to the complexity of network, the base station is required to support multiple
external interfaces and flexible networking modes.
Besides the E1 interfaces, the BTS30 also has the built-in transmission system. It
supports the 155M SDH optical interfaces. All these interfaces are provided by ASU.
The built-in transmission system makes product networking more flexible and saves
user's investment on transmission equipment.
ASU board is used in SDH transmission networks.
1) Basic features
ASU uses Huawei-developed ASIC transmission chips, so the system has an high
performance/price ratio and stability. One board integrates all the functions of
standard SDH transmission equipment including double STM-1 optical interfaces, 8
E1 electrical interfaces, full cross capabilities, 3 necessary clock phase-lock working
modes, order wire, RS232 transparent transmission serial ports, and Ethernet
interfaces.
The ASU board provides 4 E1 interfaces with re-timing functions. When users want
to use this function (e.g., in the case when GSM and DDN have very highrequirements on clock precision), this can be set through network management.
Meanwhile, in application cases such as the GSM base station and private networks,
the user can be provided with 64kbit/s sub-rate cross functions between the first 4
E1 so that maximum utilization of transmission resources are achieved.
2) Functions
The ASU SDH optical synchronous transmission system is standard STM-1
transmission equipment. Based on the existing sound technologies of Huawei
SBS155/622 products, it is fully compatible with the existing SBS155/622 products.
According to networking requirements, it can be configured as a TerminalMultiplexer (TM), Add/Drop Multiplexer (ADM) or regenerator (REG). It can be used
to form ring-, chain-, and point-to-point network topological structures. It can also be
combined with Huawei SBS155/622H and SBS155/622B products to form complex
networking structures so as to enhance network performance and provide powerful
services protection functions (channel protection or multiplexing segment protection
solutions are optional). It is a cost-effective optical transmission device built in BTS.
The ASU has inherited merits of powerful network management capacity and
convenient operations from Huawei's standard transmission equipment. It uses the
same set of network management system as all the Huawei SBS series of SDH
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optical transmission equipment. It can completely meet the OAM & P function
specified in ITU recommendations.
3) Interfaces
ASU provides the following interfaces:
Line optical interfaces: 2 (interface type: SC/PC interface)
Electrical interface: 4~8 (E1/T1)
Order wire: 1
Ethernet interface: 1
User RS232 port (point to point): 1
Network management interface: Ethernet/RS232
2.4.6 ABB
I. General
In practice, chain networking is usually adopted in BSS networking. This networking
mode has the advantage of simple structure and low cost, but also it has the
disadvantage that when power failure occurs at a site, all services of the
downstream sites will be interrupted. ABB provides of Abis interface bypass function
as a solution to the problem above.
II. Functions
ABB is applied in the environment of BTS chain networking. It is in charge of the
BTS transmission trunk. When power failure occurs at a certain level (in the middle)
of BTS in the chain networking, ABB will bypass the Abis transmission line off this
site, and directly connect it to the downstream BTS. In this way, even if power failure
occurs at the middle level site in chain networking environment, the services of the
downstream site will not be affected. See Figure 2-10 .
BSC ABB
TMU
ABB
TMU
ABB
TMU
Site1 Site2 Site3
Figure 2-10 ABB working principle
ABB can also perform loop back at the transmission line, so that in the case of
power failure at the last level BTS, ABB will loop back the E1 signal for BSC to
detect the quality of the entire transmission link.
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III. Location of Board
ABB shares the same slot with TEU, therefore the size of the board and the
interface definition is consistent with TEU. Since BTS30 has only one TEU slot, ABB
is to take the slot of TEU.
2.4.7 ABA
ABA realizes the communication between ABB and TMU. ABB communicates with
TMU via CBUS3. But the slot of ABB does not provide the connection with CBUS3.
Therefore, ABA is used to provide the connection between them. Via ABA, part of
the signals from ABB (e.g. the signals of ABA on position) can be transmitted to
CBUS3 on the backplane of common resource frame.
2.5 Other Parts of the Cabinet
2.5.1 TDU
The TDU is at the top of BTS cabinet, serving as the control center of BTS clock
transfer. It receives the clock source (SREF, OBCLK, FCLK, FN) from TMU, and
forwards the clock source to the TRXs in this cabinet and the parts in other cabinets.
TDU can also transfer other signals (e.g. alarm signals).
The main functions of the TDU are:
Provides bus-control interface
1) Clock Bus
In the simplex RS485 bus structure, it distributes the clocks generated by the active
TMU in the basic cabinet to various extension cabinets, The clock signal process is
shown in Figure 2-11 .
TMU TDUBoards in the maincabinet
Boards in theextension cabinet
A-bis
Figure 2-11BTS clock signal process
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The TDU of each cabinet is connected to the bus. After receiving clock signals, it
transfers them to the TRX in the local cabinet.
The TDU of the last cabinet is connected to an adapter. All the TDUs form a
chrysanthemum ring of a clock bus. as shown in Figure 2-12 .
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRX
PMU
TMU
TMU
Basic Cabinet
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRXPSU
PMU
Extension Cabinet
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRX
PMU
Extension Cabinet
PSU
PSU
Figure 2-12Clock bus connection in a synchronous cell
Connection path:
Upper cabinet TDUJP3
TDUJP1
TRBJC2
Cabletransfer Inner cabledistribution (Connect with 6 TRXs)Matching
Lower cabinet TDUJP4
TDUJP2
CMBJ24
Inner cabledistribution
Cabletransfer Cable
transfer
Inner cable
distribution
Figure 2-13Clock bus connection path
For the upper cabinet, JP3 should be configured with connector. For the lower
cabinet, JP4 should be configured with connector.
2) Data Bus (DBUS)
DBUS is for the data connection between TMU and TRX. Each TMU provides 2 full
duplex DBUS link and TRX connection, called DBUS1 and DBUS2.
The physical feature of DBUS is differential RS485, TDMA synchronous bus and
distribution of 32 timeslots is similar to that of PCM.
The active TMU has DBUS connections to each TRX in the same cabinet. The
active and standby links are led from the main cabinet to the 18 TRXs in the local
cabinet group. There is no DBUS connection between cabinet groups.
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For example, the signal connection between BTS30 cabinets is shown in Figure
2-14 .
Figure 2-14DBUS connection between BTS30 cabinets
The intra-cabinet signal connection is shown in Figure 2-15 .
Upper cabinetTDUJP6
TDUJP5
Cabletransfer
Inner cabledistribution
CMB J25(connect with TMU)
Inner cabledistribution
TRBJC3
TRBJC1
TDUJP7
TDUJP8
Inner cabledistribution
Cabletransfer
Lower cabinet
Inner cabledistribution(connect with 6 TRXs)
Figure 2-15DBUS connection path
For the upper cabinet, JP6 should be configured with connector. For the lower
cabinet, JP8 should be configured with connector.
3) Control Bus (CBUS)
CBUS1 is for the communication between the TMUs of this same site. It adopts
RS485 semi-duplex bus, asynchronous transmission. The link layer conforms to
HDLC protocol. The bus rate is 256 kbit/s.
Since only the PCM link in main cabinet group has the operation and maintenance
signaling of BTS. The master TMU in main cabinet group is to send the operation
and maintenance signaling to the slave TMUs in the two extension cabinet groups,
as shown in Figure 2-16 .
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Figure 2-16CBUS1 connection between BTS30 cabinets
The connection of the intra-cabinet signal is shown in Figure 2-17 .
Upper cabinet TDUJP3
Cabletransfer TDU
JP2
Inner cabledistribution CMB J24
(connect with TMU)
TDUJP4
TDUJP2
CMBJ24
Inner cabledistribution
Cabletransfer
Lower cabinet
Figure 2-17CBUS1 connection path
CBUS2 is for the control link between TMU and TRX.
The physical feature is differential RS485 interface, semi-duplex bus. The link layer
conforms to HDLC protocol. The bus rate is 2 M. The 2 M clock of DBUS is used as
the clock of CBUS2. There is no CBUS2 connection between cabinet groups.
The connection relationship between CBUS2 cabinet groups and the connection
path are similar to that of DBUS.
CBUS3 is for the connection between TMU and some low rate control parts, such as
CDU, PMU and environmental monitoring instruments.
The physical feature is differential RS485 interface. The link layer conforms to DLC
protocol, differential transmission and master/slave communication. The bus rate is
9.6 kbit/s. There is no CBUS3 connection between cabinet groups.
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Figure 2-18Connection of CBUS3 between BTS30 cabinets
The connection of the intra-cabinet signal is shown in Figure 2-19 .
Upper cabinet TDUJP6
TDUJP18
TDUJP5
Cabletransfer
Cabletransfer
Alarm box
CMB J25(connect with TMU and PMU)
TRBJC3
Inner cabledistribution
TRBJP1
TRBJP2
TRBJP3
Cabletransfer
CDU
Inner cabledistribution
CDU
Inner cabledistribution
CDU
Inner cabledistribution
TRBJC1
TDUJP7
Inner cabledistribution
Cabletransfer
Inner cabledistributionTDU
JP8
Cabletransfer
Lower cabinet
Figure 2-19CBUS3 connection path
For the upper cabinet, JP6 should be configured with connector. For the lower
cabinet, JP8 should be configured with connector.
4) Frequency Hopping Bus (FHBUS)
FHBUS is used in baseband FH. FHBUS physically shares the same cable with
CBUS2, CBUS3 and DBUS. The difference is that FHBUS connects only to TRX.
FHBUS is an 8 bit parallel bus, semi-duplex, and conforms to RS-485 criteria.
FHBUS is for the connection between all TRXs in the same cabinet group (forBTS30, at most 18). There is no FHBUS connection between cabinet groups.
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Main cabinet Extension cabinet
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRX
PSU
PMU
TMU
TMU
Extension cabinet
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRX
PSU
PMU
CDU
TRX
CDU
CDU
TRX
TRX
TRX
TRX
TRX
PSU
PMU
Figure 2-20FH bus connection between BTS30 cabinets
Connection path is shown in Figure 2-21 .
Upper cabinet TDUJP6
Cabletransfer TDU
JP5CMBJ25
Inner cabledistribution
TRBJC3
TRBJC1
TDUJP7
TDUJP8
Inner cabledistribution
Cabletransfer Lowercabinet
Inner cabledistribution
Inner cabledistribution(connect with 6 TRXs)
Figure 2-21FH bus connection path
For the top level of cabinet, JP6 should be configured with connector. For the last
level of cabinet, JP8 should be configured with connector.
Transfers E1 signals in the local cabinet
TMU provides 4 sets of identical circuits E1 for lines. Plus the 4 E1 lines on the
standby TMU board, there are altogether 8 E1 signals that are transmitted on the
coaxial cable to each cabinet top where the TDU sends them via coaxial cable to
BSC.
Provides alarm channels
Inputs of 8 external and 16 extended digital alarm signals and 8 analog alarm
signals, as well as outputs of 8 digital control signals, are sent via the TDU to the
TMU board and the environment alarm box (for detailed description, refer to section
2.7.1 of this chapter).
The input of the DC alarm signals of fuses and output of DC contactor control
signals are also sent via the TDU to the PMU of this cabinet.
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2.5.2 FMU
FMU is in the fan box, used to control the fans.
The small size of the base station cabinet sets higher requirements for heatdissipation. A perfect heat dissipation design should include air tunnels (mainly
related to structure), expected dissipation amount (mainly related to circuit working
temperature, environment temperature, system total power and efficiency), original
calculation of system heat (simulation makes better result if tools are available), fan
type, fan monitoring unit, and system heat design testing and verification, etc.
The functions and circuits of FMU are based on the fan type, specific fan control
requirements and control modes, as well as the specific system heat design.
It performs the following main functions:Fan feeding
This part of circuit consists of power supply filtering and power supply voltage
dropping. It completes the processing works from system power supply to the
working power supply needed by fans, and provides feed to the fans.
Fan speed control
It controls the fan speed so that the fan can maintain a constant rotation speed,
meeting the system heat design requirements.
Alarm detection
Fan faults have 2 types, blocking and short-circuiting, both may stop fan running.
The FMU monitors the fan rotation speed, and determines the fan status (normal or
faulty). If fault is detected, alarm will be reported to the PMU.
Interfaces
The FMU provides the following ports: fan 24V power supply input port, fan box
power supply input port, and fan fault alarm terminal, which outputs low levels in
case of fan failure.
2.5.3 Switch Box
The +26V DC from the output busbar of the power supply backplane is inputted to
the switch box, and after passing the air switches for different power consumption
units and over-current protectors, it is outputted to the terminals on the backplane.
These terminals are connected to the power input terminals of different power
consumption units, thus achieving distributed power supply.
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The distributed power supply ensures the normal power supply to other units when
the supply to one unit fails.
The power supply to CDU, EDU, TRX, TMU, PBU, etc., can be controlled through
the switches on the front panel of the switch box.
2.5.4 Fan Box
There are two kinds of fan boxes, one small fan box below the switch box, and two
large boxes below the second TRX/CDU frame. Both kinds of fan boxes are
equipped with FMU.
The fan box uses mixed-flow fans, which feature strong wind rate and pressure. The
FMU ensures the normal operation of fans, and reports alarms in case of failure.
2.5.5 Air Box
The air box is at the bottom of the cabinet, under the first TRX/CDU frame. It is the
channel for introducing the external cool air into the cabinet to ensure the normal
operation of the whole BTS system.
2.6 Antenna and Feeder System
The antenna and feeder system of the base station mainly consists of the antenna,feeder, jumper, lightning arrester, tower-top amplifier (optional), etc. as shown in
Figure 2-22 . Its main function is to transmit modulated signals and receive signals
from mobile stations.
C a b
i n e t
Tx/Rx antenna
T o w e r - t o p
a m p l
i f i e r
Diversity Rx antenna
L i g h t n i n g
a r r e s
t e r
Antenna and Feeder System
Feeder
Feeder
T o w e r - t o p
a m p l
i f i e r
L i g h
t n i n g
a r r e s t e r
Figure 2-22Composition of antenna system
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2.6.1 Antenna
The antenna is the terminal of transmitting and the start of receiving. Antenna type,
gain, coverage pattern (including azimuth angle, pitch angle and declination angle),and front/back ratio will affect system performance. A network planner sets these
parameters according to network requirements.
I. Antenna gain
Antenna gain indicates the antenna feature of electromagnetic radiation in specific
directions. Normally, the higher the gain, the stronger the field strength in the main
beam radiation direction (which means a larger coverage area), but nearby blind
area might occur.
II. Antenna pattern
The antenna pattern describes the radiating abilities of antennas in all directions.
(usually in terms of horizontal azimuth angle and declination angle).
Usually, there are two kinds of base station antennas: omni and directional antennas
according to the azimuth angle: Omni antenna radiates the waves in all directions i.e.
along 360 degrees, whereas directional antennas radiates along 120, 90, or 65
degree.
The declination angle of the antenna can be achieved through mechanicaladjustment or electric tuning. BTS directional antennas with declination angle of 0
or 2 are available. Through adjustment by pitch adjuster, a wider angle can be
achieved (e.g. 0 ~ 10 ).
III. Polarization
Polarization is used to describe the direction of electric field. Mobile communication
antennas include single polarization antennas and dual polarization antennas. For
the later antennas, two antenna's polarization directions are vertical to each other.
So using of dual polarization antennas can reduce the number of antennas needed.
IV. Diversity
Radio communication is much more complex than fixed line communication
because of electromagnetic waves propagation. In urban areas, the propagation of
electromagnetic wave has the following features:
The average value of field strength varies slowly with distance and time. Such
variation abides by the logarithmic normal distribution. This is called slow
fading.
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The instantaneous value of field strength presents a selective fading along
transmission paths due to multi-path transmission. Its fading pattern abides by
the Rayleigh distribution. This is called fast fading.
Either fast fading or slow fading will affect the quality of mobile communications, oreven lead to communication interruption. The diversity receiving technology is one
of the most effective ways to deal with fast fading. Two receiving signals from two
different antennas effectively decrease the fading effect.
Diversity includes polarization diversity and space diversity. In existing mobile
communication systems, either the space diversity or polarization diversity can be
used. Theoretical inferences show that in case of space diversity, when the distance
between two antennas is greater than 10 wavelengths, desirable diversity gain can
be obtained. Polarization diversity enjoys the advantage of convenient antenna
installation and space saving and is more widely used nowadays.
V. Antenna spacing
To reduce interference on the receivers, enough spacing should be reserved
between receiving and transmitting antennas. Spacing is determined by the
out-band noise of the transmitter and receiver sensitivity. In the GSM system, the
antenna spacing should be greater than 30dB.
2.6.2 Feeder
To reduce transmission loss, the base station uses low loss RF cables. There are
several types of main feeders available, including 7/8-inch and 5/4-inch. 1/2-inch
super-flexible jumpers are used between the antenna and the main feeder, between
the antenna and the tower-top amplifier, and between the cabinet and the lightning
arrester.
2.6.3 Lightning Arrester
The lightning arrester is used to prevent damage of lightning current to the antenna
and feeder system. Usually, there are two kinds of lightning arresters. The first type
applies the microwave principle to conduct the low frequency lightning current to the
ground so as to discharge the current. The second one is a discharging tube, when
the voltages at both ends of the discharging tube reach a certain value, the tube
conducts and discharges the large current. The second technique is used in the
BTS30.
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2.6.4 Tower-top Amplifier (Optional)
To further improve the signal quality, Huawei BTS30 offers a complete solution by
providing the tower-top amplifier.The tower top amplifier is optional. Normally it is installed close to the antennas,
consisting of triplex filter and low noise amplifier. The triplex filter is actually a device
composed of two duplex filters.
Signals from the antennas first pass through the triplex filter to filter out the out-band
interference, then the low noise amplifier amplifies the weak signals. Finally the
amplified signals are sent over the low loss cable to the BTS, as shown in Figure
2-23 .
The purpose of the tower top amplifier is to enhance the receiving sensitivity of thebase station. So the tower-top amplifier is required to have a low noise coefficient.
The power of the signals received on the antenna varies greatly with the distance
between the MS and the base station. This requires that the tower- top amplifier
have a greater dynamic range.
Besides, the tower-top amplifier also has the by-pass function in case of DC power
failure.
The DC power supply of tower-top amplifier is fed through the center conductor of
the receiving feeder by the CDU. Since it is an outdoor device, a reliable waterproofsealing is required.
The tower-top amplifier can operate under -40 C~60 C.
Bias-T
Low noiseamplifier
Transmitting filter
Receivingfilter
By-path
DC
BTS
Triplex tower-top amplifier
Receivingfilter
Figure 2-23Structure of the triplex tower-top amplifier
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2.7 Power Supply System
2.7.1 Overview
The BTS30 built-in power supply system provides +26V DC to the base station.
Together with power distribution, lightning arrester, and monitoring systems, they
form a complete power supply system.
To meet the power supply requirements of different users, two special AC/DC and
DC/DC power supply systems are provided, which are used respectively for the AC
power supply cabinet and the DC power supply cabinet.
The AC/DC power supply system has battery charging functions. The PSU power
supply unit described above consists of the AC/DC power supply module and theDC/DC power supply module.
According to the general design requirements of the BTS30, multiple cabinets can
be configured at a site, which are interconnected via multiple sets of buses to
achieve flexible, convenient and reliable network configurations. So a proper power
distribution monitoring solution is required for the power supply system, e.g.,
centralized anti-lightning protection, and AC and DC power distribution. That is, each
cabinet should have its own power supply system.
The power supply monitoring board installed on each cabinet monitors its own
power supply module and part of environment parameters inside the cabinet, and
reports them to TMU via general monitoring bus.
The AC and DC inputs of the system has the following 3 modes, among them only
one can be selected:
220VAC: used for the AC power supply cabinet, with the AC/DC module and
batteries attached.
-48VDC: used for the DC power supply cabinet with the DC/DC module, no battery
attached.
+24VDC: used for the DC power supply cabinet, without AC/DC module or DC/DC
module, nor any battery.
The power supply input goes through the AC EMI filter or DC EMI filter to the wiring
terminals on the top of the cabinet, then to the backplane busbars in the common
frame. 220V AC and -48V DC are input to different sockets from the backplane
busbar, so as to avoid mistaken insertion.
No matter whether it is the 220V AC power distribution, -48V DC power distribution
solution, or the +24V power distribution, their outputs are all collected to the output
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busbars of the power supply backplane. Then, the 26V DC is led out from the
busbar, along the cabinet wiring trough to the copper bar of the distribution box.
The 26V DC input from the battery is connected to the current diverter on the power
supply backplane, and then distributed through the distribution copper bar in thedistribution box to various power-consuming modules. They are respectively led out
from the distribution copper bar, passing the over-current protection devices set
separately for each power-consuming unit in the distribution box, and then
connected to the outlet terminals on the backplane of the distribution box. When the
power to a unit is cut due to over-current, other units will not be affected.
The illustration of the entire power supply system is as shown in Figure 2-24 .
Anti-lightning
power
distribution
Battery group Fuse
AC/DC(DC/DC)module
AC/DC(DC/DC)
AC/DC(DC/DC)
EMIfilter
EMIfilter
EMI filter
220V AC IN
-48V DC IN
+24 VDC IN
PMU
26V DC OUT
DC contactor
Load
module module
AC/DC(DC/DC)module
Figure 2-24The BTS30 power supply system
2.7.2 Overall Structure
I. AC/DC power supply system
220V AC is led in after passing through the AC input anti-lightning power distribution
unit and the AC EMI filter on top of the cabinet. It then passes downward along the
cabinet wiring trough to the input busbar on the backplane of the power supply
frame.
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On this backplane, there are the 220V AC power supply busbar, -48V DC busbar,
and 26V DC busbar. When the AC/DC power supply module is used, the -48V DC
busbar should not be connected to.
A fully configured cabinet uses the 4 AC/DC (26V/25A) modules (3 active + 1standby), which can ensure a maximum output of 2600W.
The module size is 285mm233mm (6U)60.5mm(12E).
The structure of the AC/DC power supply system is shown in Figure 2-25 (For the
battery part, refer to Figure 2-24 ).
AC input anti-lightning power distribution unit A1441Z
PSU PSU PSU PSU
220V AC INPUTInput busbar
Output busbar
26V DC OUTPUT
DC distribution copper bar
PMU
Figure 2-25Structure of the AC/DC power supply system
II. DC/DC power supply system
The DC/DC power supply system uses a backplane the same as that for the AC/DC
system. -48V DC first passes through the DC EMI filter on top of the cabinet, then
downward along the cabinet wiring trough to the input busbar of the power supply
backplane.
On the backplane of the power supply frame, there are 220V AC, -48V DC and 26V
DC power supply busbars. When the DC/DC power supply module is used, the
220V AC busbar should not be connected to.
In full configuration, 4 DC/DC 26V/25A modules (3 + 1 standby) are used to provide amaximum output of 2680W.
The module size is the same as that of the AC/DC module, i.e., 285mm233mm (6U)
60.5mm (12E).
The structure of the DC/DC power supply system is shown in Figure 2-26 .
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PSU PSU PSU PSU
Input busbar
Output busbar
26V DC OUTPUT
DC distribution copper bar
-48 V DC INPUT
PMU
Figure 2-26Structure of the DC/DC power supply system
2.8 Environment Monitoring System
It is not practical to monitor the BTS locally. Compared with the switch room, the
facilities in the BTS room are quite simple, and their operation environment can be
rather hostile. To ensure the normal operation of the base station equipment, and to
cope with various possible emergencies (e.g. fire, floods), a perfect environment
monitoring system is required.
The environment monitoring system consists of BTS alarm port and environment
monitoring instrument. BTS30 supports 14 switching/digital inputs, 8 digital outputs
and 8 analog inputs, collects external alarms and controls external equipment.
EAC1 and EAC2 on the cabinet top are the physical ports for external extended
alarm and EAC alarm report.
The environment monitoring instrument is used to get the information on external
environment. It reports the alarm to BSC via TMU if the external environment
parameters meet the corresponding alarm terms. The external extended alarm is
switching (digital) signals, which is different from the EAC alarm.
The following gives the alarm functions provided by the environment monitoring
instrument.
2.8.1 Outlook of Environment Monitoring Instrument
The environment monitoring instrument consists of such sensors as host, humiture
probe, smoke probe, infrared probe, infrared tube, door status (position) switch etc.
Each probe connects to the host with cables.
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Dimensions of the host:
Length (L) x Width (W) x High (H) = 390mmx270mmx55mm. The outlook of the
environment monitoring instrument is shown in Figure 2-27 .
Figure 2-27Outlook of Environment Monitoring instrument
2.8.2 Function Provided by Environment Monitoring Instrument
The environment monitoring instrument automatically monitors and generates
temperature, humidity, smog, and intruder alarms according to the set values.
Besides, it can start corresponding protection devices for fire-fighting moistening
and anti-burglary protection, etc. Moreover, it can receive commands from the
control center to modify parameters and start/stop protection devices.
The features of the environment monitoring instrument include:
Realtime display of temperature and humidity
Time display
Generating alarms including fire, smog, temperature, humidity, water and 3
kinds of burglar alarms
A panel control keyboard
10 switch parameter inputs (opto-electrical isolation)
6 relays (maximum 5A/220V) to drive external executors
2 PWM (pulse width modulation) outputs (8-bit resolution, with a basic clock
500kHz)Driving of 7 independent open-collector gates (absorbing current: 300mA)
Capable of communicating with TMU via the RS422 port
2.8.3 Environment Monitoring Instrument Inputs
Temperature: frequency-type temperature and humidity transducer
Humidity: frequency-type temperature and humidity transducer
Smog: Ion type smoke sensitive probe or opto-electrical type smoke sensitive
probe
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Flame (optional): fire probe or high temperature difference sensitive probe
Anti-burglary detection: infrared detector, opto-electrical detector, and magnetic
sensor
Other sensor inputs: besides the quantitative temperature and humidity signalparameters, the above sensor input signals can be extended into 10 switch
parameters
2.8.4 Alarm Indicators
Ten red indicators on the panel are provided, which correspond sequentially to the
following alarm parameters:
Fire alarm: fire alarm is determined by the high temperature and smog probe
Smog alarm: smog sensor timeout alarm
Temperature upper limit: an alarm is generated when the environmenttemperature exceeds the set temperature limit
Temperature lower limit: an alarm is generated when the environment
temperature is lower than the set temperature limit
Abnormal humidity: an alarm is generated when the environment humidity goes
beyond the normal range between the upper and lower limits
Water: the alarm is generated when water is detected
Air-conditioning: an alarm is generated in case of failure of air-conditioning
equipment.
Opto-electrical: used for anti-burglary purpose, the alarm is generated when theopto-electrical switch is triggered.
Infrared: used for anti-burglary purpose, the alarm is generated when the
infrared sensor detects outputs.
Access control: used for anti-burglary purpose, the alarm is generated when
the magnetic access control switch is triggered.
If there are multiple input signal channels for the same kind of sensor, alarm in any
channel will be regarded as the same kind of alarm, regardless of the specific
channel sending the alarm. Except temperature and humidity sensors, all other
sensors can be extended up to 10 channels at the most.
2.8.5 Executing Devices
The BTS30 environment monitoring function involves the following executing
devices:
Six constant on/off relays (A~F) which function as the control and protection
devices, operating under 1A/220V. Their specific application can be determined by
the user. Their default settings are as follows:
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the same as that of the first level. The protection circuit of the third level clamps the
residual voltage at about 100V.
Its functional blocks are shown in Figure 2-28 .
Over-currentprotection
Inductor Inductor -48V -48V
GND GND
Input Output
Over-currentprotection
Over-currentprotection
Over-currentprotection
V-sensitiveresistor
V-sensitiveresistor
V-sensitiveresistor
TVScomponent
Figure 2-28Functional blocks
2.9.2 Lightning Protection for AC Power Supply
I. Lightning current lead-in paths
AC power supply suffers directly from lightning strike or induced lightning.
II. Principle of the AC lightning arrester
The principle of the AC lightning arrester is similar to that of the DC lightning arrester.
The functional blocks are shown in Figure 2-29 .
Slow-blow fuse
V-sensitive resistor
Discharge tube
Inductor
Air switchIN OUT
V-sensitivecomponent
Figure 2-29Functional blocks of the AC lightning arrester
The lightning protection system features:
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Symmetric design, N and L wires can be connected freely without affecting the
performance.
2-level lightning protection guarantees high reliability and less possibility of
damage by lightning strikes.2-level protection and 2-level alarm are provided (visible alarm. If either level
fails, corresponding indicator will be off. On/off signals of the dry contactor are
also provided). The circuits are designed in parallel so that the maintenance
personnel can repair them without power-off.
The total through-flow current is 40A. There are two output terminals so that
two cabinets can share one anti-lightning box.
2.9.3 Lightning Protection for Trunk Cables
There are three kinds of trunk cables in BTS30: 75 coaxial cable (E1), 120 twisted-pair cable (E1) and optical fiber (SDH). In case of optical fiber connections,
fiber pigtail is used so that its lightning protection is not considered.
BTS30 E1 interface protection is realized by adding a E1 lightning protection board
to the top of the cabinet. Each board has eight pairs of E1 protection units and two
DB37 connectors. The E1 lightning protection board is illustrated in Figure 2-30 .
TX0
TX1
TX2
TX3
TX4
TX5
TX6
TX7
RX0
RX1
RX2
RX3
RX4
RX5
RX6
RX7
T o
L i n e
T o
E q u
i p m e n
t
LightningProof Box
Figure 2-30E1 lightning protection board
All E1 cables are protected by the lightning protection board, which is able to avoid
the thunder current from entering the cabinet via E1 cable. Even the strong current
impact can be discharged by the discharging tube. The lightning protection board is
illustrated in Figure 2-31 .
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E1-Tip E1-Tip
E1-Ring E1-Ring
PE PE
Discharging tube
Discharging tube
4.7
4.7
Figure 2-31Circuit of lightning protection board