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Technical Manual Auxiliary SystemM900/M1800 BTS3012A Base Transceiver Station Table of Contents
Huawei Technologies Proprietary
i
Table of Contents
Chapter 1 Introduction to Auxiliary System ...............................................................................1-11.1 Overview............................................................................................................................ 1-11.2 Introduction to Auxiliary System ........................................................................................ 1-1
Chapter 2 Power Supply System................................................................................................. 2-12.1 AC/DC Distribution Unit ..................................................................................................... 2-1
2.1.1 Overview ................................................................................................................. 2-12.1.2 AC Power Distribution Principle .............................................................................. 2-12.1.3 DC Power Distribution Principle.............................................................................. 2-4
2.2 TSU.................................................................................................................................... 2-62.3 Storage Batteries............................................................................................................... 2-7
2.3.1 Built-in Storage Battery Box.................................................................................... 2-72.3.2 Extended Storage Battery Cabinet.......................................................................... 2-7
Chapter 3 Environment Monitoring System ...............................................................................3-13.1 Overview............................................................................................................................ 3-13.2 TCU.................................................................................................................................... 3-2
3.2.1 Overview ................................................................................................................. 3-23.2.2 Architecture and Principle ....................................................................................... 3-3
3.3 EMUA................................................................................................................................. 3-43.3.1 Performance Index.................................................................................................. 3-43.3.2 Functions................................................................................................................. 3-5
Chapter 4 Temperature Adjustment System ..............................................................................4-14.1 Overview............................................................................................................................ 4-14.2 Air Conditioner ................................................................................................................... 4-14.3 Heat Exchanger ................................................................................................................. 4-1
Chapter 5 Transmission Mode..................................................................................................... 5-15.1 E1 Transmission ................................................................................................................ 5-15.2 SDH Transmission............................................................................................................. 5-3
5.2.1 Ring Networking...................................................................................................... 5-35.2.2 Chain Networking.................................................................................................... 5-4
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Chapter 1 Introduction to Auxiliary System
1.1 Overview
The auxiliary system refers to the equipment and devices in various working systems
that assist the normal operation of BTS. To help introduce the auxiliary system in this
manual, all the functional boards in BTS3012A are referred to as the main equipment,
and the other devices in the BTS3012A are referred to as the auxiliary equipment.
The principles of the all the boards in BTS3012A are described in M900/M1800
BTS3X Series Base Transceiver Station Technical Manual - System Principle. Thecomponents of the BTS3012A auxiliary system include power distribution system,
environment monitoring system and temperature adjustment system, as illustrated in
Figure 1-1.
Figure 1-1 Components of BTS3012A auxiliary system
In addition, this manual also describes the transmission equipment principle and
lightning protection.
1.2 Introduction to Auxiliary System
I. Power Distribution System
The power distribution system supplies power for the stable working of BTS main and
auxiliary equipment.
The BTS3012A power distribution system consists of three parts:
z AC/DC power distribution unit
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z Transmission power supply Unit (TSU)
z Storage batteries
II. Environemtn Monitoring System
The environment monitoring system accomplishes the monitoring of the environment
variables in the cabinet and the alarm processing functions to keep the cabinet in a
suitable temperature and humidity range and ensure safe and reliable operations of
the equipment.
TCU, EMUA and sensors are the major components of the environment monitoring
system.
III. Temperature Adjustment System
The temperature adjustment system can adjust the internal temperature of the
cabinet to get the main equipment to work reliably in a mild environment. The air-
conditioner and the heat exchanger are the major component of temperature
adjustment system.
IV. BTS Transmission Equipment
Many types of small transmission equipment can be embedded in BTS3012A to
support various transmission modes, including:
z E1 (75 ohm/120 ohm)z SDH
z Microwave
V. BTS Lightning Protection Grounding
As an outdoor macrocell BTS, BTS3012A is required to have higher lightning
protection performance. Therefore, all ports where lightning might be led to, including
AC power port, E1 port and antenna and feeder ports, have been designed with
comprehensive lightning protection techniques.
Note:Some of the above auxiliary equipment are optional. If no special note is given in the
following chapters, the equipment mentioned is mandatory.
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Chapter 2 Power Supply System
The power supply system of BTS3012A consists of the AC/DC distribution unit,
transmission power supply unit (TSU), and storage batteries.
2.1 AC/DC Distribution Unit
2.1.1 Overview
Functionally, the AC/DC distribution unit accomplishes two functions:
z AC distribution
z DC distribution
The AC distribution unit is further divided into two parts:
z AC distribution part supplying power to the main equipment
z AC distribution part supplying power to the auxiliary equipment
Figure 2-1 shows the AC/DC power distribution principle of BTS3012A.
PSU
subrack
220 V ACpower input
220V AC
Auxiliary
equipment
+24V DC
DC power distribution
part for main
equipment+24V DC
Batteries
Auxiliary
devices
Main
equipment
AC powerdistribution
unit
DC power distribution
unit for auxiliary
equipment
Figure 2-1 Principle of AC/DC distribution unit
2.1.2 AC Power Distribution Principle
The AC power distribution unit of BTS3012A supports:
z 220 V AC three-phase power distribution
z 220 V AC single-phase power distribution
z 110 V dual-live power distribution
I. 220 V AC Three-Phase Power Distribution
The three-phase 220 V AC power travels through the lightning protecting module and
the EMI filter, and then is accessed to the AC power distribution unit. The power is
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further distributed to the TCU, air conditioner or heat exchanger, PSU and the
standby socket. The input end of each phase is protected by a miniature circuit
breaker (MCB). Refer to Figure 2-2 for the AC power distribution principle.
EMIfilter
TCU
Air conditioner or
heat exchanger
Contactor
Socket
PSU
subrack
L3
L2
L1
N
Arrester
Gounding barPMU
TCU switch
ACU/HX switch
L3
L2
L1
N BTS switch
AUX switch
L
N
L
N
L
N
L
N
AC power distribution unit
DC power
distributionunit
220V AC
input
Figure 2-2 Principle of AC power distribution unit (220V AC three-phase distribution
mode)
II. 220V AC Single-Phase Power Distribution
When the 220V AC single-phase power distribution is adopted, the single-phase
power distribution mode is converted to three-phase power distribution mode throughthe power engineering interface box. The power distribution principle in the cabinet is
the same as that of the 220 V AC three-phase power distribution mode as shown in
Figure 2-3.
EMI
filter
TCU
Air conditioner or
heat exchanger
Contactor
Socket
PSUsubrack
L3
L2
L1
N
Arrester
Grounding barPMU
TCU switch
ACU/HX switch
L3
L2L1
N BTS switch
AUX swtich
L
N
L
N
LN
L
N
220V AC
input
M
C
B
L
N
AC power distribution unit
DC power
distribution unit
Figure 2-3 Principle of AC power distribution unit (220V AC single-phase distribution
mode)
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III. 110V AC Dual-Live Power Distribution
When the 110V AC dual-live power distribution is adopted, the power input adopts the
method of 2-channel L and 1-channel N.as shown in Figure 2-4.
173220VAC
L1
L2
L3
L1
L2
N
100127VAC
100127VAC200254VAC
Phase voltage 100127VACLine voltage 173220VAC
173220VAC
Three phase star
four wiredearthed neutral
Single phasethree wired
earthed neutral
Phase voltage
Line voltage
Figure 2-4 Power input mode of 110V AC dual-live cable power supply
The principle of power distribution inside cabinet is the same as that of 220 V AC
three-phase power distribution. The power input connection is different. Figure 2-5
shows the principle.
EMIfilter
TCU
Air conditioner or
heat exchanger
Contactor
Socket
PSU
subrack
L1
L2
Arrester
Grounding barPMU
TCUswitch
ACU/HXswitch
L3
L2
L1
N BTS switch
AUX switch
L
N
L
N
L
N
L
N
AC power distribution unit
DC power
distribution unit
L3
L2
L1
N
N
Figure 2-5 Principle of AC power distribution unit (110V AC dual-live distribution
mode)
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2.1.3 DC Power Distribution Principle
The DC power distribution unit of BTS3012A is responsible for the distribution of +24
V DC output from the PSU. The AC/DC conversion is accomplished by the PSU. SeeFigure 2-6 for the principle of AC/DC conversion. The 220 V AC is output from the AC
power distribution unit to the 220 V AC input busbar on the backplane of the public
resource frame. Then it is converted to multiple channels of +24V DC by the PSU
(AC/DC) module on the backplane and is output to the output busbar.
AC input lightning protection power distribution unit A1441Z
PSU PMUPSU PSU
220 V AC input
+24 V DC output
Input bus bar
Output bus bar
DC ditribution copper bar
Figure 2-6 Principe of AC/DC conversion
DC distribution copper bar allocates the +24 V current output from PSU to two units:
z Power distribution unit for auxiliary equipment
z Power distribution unit for main equipment
I. DC Power Distribution for Auxiliary Equipment
The DC power distribution for auxiliary equipment outputs 6 channels of DC to the
following devices:
z TSU
z Backup switches
z Fans for auxiliary equipment
z Lights
z Storage batteries
z Storage battery cabinet
See Figure 2-7 for the principle of DC power distribution for the auxiliary equipment.
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TSU switch
SPARE switch
Heat exchanger
switch
Fan of auxiliary
equipment switch
LAMP switch
Contactor Fuse
Batterycabinet
Battery
cabin
+24V DC
DC power distribution unit
for auxiliary equipment
TSU
Backup switch
Heat
exchanger
Fan of auxiliary
equipment
Lamp
Figure 2-7 DC power distribution for auxiliary equipment
II. DC Power Distribution Principle for Main Equipment
The DC power distribution unit outputs 14 channels of DC to the following devices:
z TRXs
z
CDUsz TMUs
z The fan for the main equipment
See Figure 2-8 for the principle of DC power distribution for the main equipment.
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DC power distribution unit
for main equipment
+24V DC
2TRX
2TRX
2TRX
2TRX
2TRX
2TRX
CDU
CDU
CDU
CDU
CDU
CDU
TMU
Fan of mainequipment
Figure 2-8 DC power distribution for main equipment
2.2 TSU
Note:The TSU is an optional device.
BTS3012A provides three types of power supply for its built-in transmissionequipment:
z +24 V DC
z 220 V AC
z -48 V DC
The transmission power supply unit (TSU) is a DC/AC converter that converts +24 V
DC output power from the PSU to -48 V DC power that can be used by the built-in
transmission equipment. The TSU works in the 1+1 backup mode. Normally, the two
TSUs output equalized current. When one TSU gets faulty, the other TSU supplies
power to the transmission equipment and reports alarms.
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2.3 Storage Batteries
Note:Storage batteries are optional.
When the mains supply is cut off, BTS3012A can continue its services with the power
supply from storage batteries. The built-in storage battery box and extended storage
battery cabinet are provided for BTS3012A.
2.3.1 Built-in Storage Battery Box
The built-in storage battery box is installed in the auxiliary equipment and
accommodates two 100 Ah storage batteries. It can sustain the service of three
BCCH carriers for above 30 minutes when the mains supply is cut off.
The technical indices of a common storage battery are listed below:
z Rated voltage: 12 V DC
z Rated capacity: 100 Ah
z Working temperature:-15C to +45C
z Floating voltage: 13.38 V (+25C)
z
Maximum charging current: 25 A
2.3.2 Extended Storage Battery Cabinet
The extended storage battery cabinet has more powerful power backup capacity. It
can accommodate twenty four storage batteries with rated voltage as 2 V to improve
the power supply duration after the mains supply is cut off. Under full configuration of
the BTS3012A, the power backup duration is more than 4 hours.
Technical indices of the extended storage battery cabinet are listed below:
z Rated voltage: 24 V DCz Rated capacity: Optional (400 Ah, 650 Ah)
z Working temperature: -20C to +50C
z Floating voltage: 26.8 V (+25C)
z Maximum charging current: 130 A
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Technical Manual Auxiliary SystemM900/M1800 BTS3012A Base Transceiver Station Chapter 3 Environment Monitoring System
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Chapter 3 Environment Monitoring System
3.1 Overview
As the core control system of BTS3012A, the environment monitoring system is
responsible for monitoring and controlling the environment in BTS3012A. The system
consists of the following parts:
z Sensors
z Temperature control unit (TCU)
z PMU
z TMUz EMUAThe specific functions of these parts are described as follows:
1) Sensors are embedded in the BTS3012A cabinet and the extended storage
battery cabinet. Environment variables are collected by PMU.
z The BTS3012A cabinet contains the temperature sensor, door control sensor,
water sensor and smog sensor.
z The extended storage battery cabinet contains the temperature sensor and door
control sensor.
2) TCU provides temperature protection for the main equipment. When the
temperature is too high or too low, TCU will cut off the 220 V AC input power and
the +24V DC output power from the storage batteries and switch off some of the
boards to prevent damage to the main equipment.
3) TMU collects the Boolean values of the alarm input of the TSU, AC lightning
protection unit, regulator and the air-conditioner through the temperature control
backplane (TCB).
4) EMUA is used for monitoring environment parameters and voltage of BTS3012A,
and for real-time detecting relevant electric amperage or non-electric amperage
when equipped with a sensor. Its functions includes 32 channel extended
Boolean value detection, 4 extended analog input, 6 channel relay output, and
basic environment parameter monitoring.
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Sensor
AC lightning
protection
board
TMU
PMU
EMUA
Air conditioner/
Heat exchanger
TRX/CDU
Battery
TCU
Controlsignal
Alarm
signal
Temperature
WaterSmoke
Access control
Monitoring
subsystem
Control
signal
Controlsignal
Figure 3-1 BTS3012A environment monitoring system
Note:The detailed function description of PMU and TMU is given in M900/M1800
BTS3012A Base Transceiver Station Technical Manual - System Principle, so they will
not be repeated here.
3.2 TCU
3.2.1 Overview
The temperature control unit (TCU) has two functions:
z Monitoring the temperature in the cabinet in real-time. By controlling the power
distribution of the cabinet, it prevents over-high or over-low temperature from
damaging the equipment and components. In this way, the normal working of the
main equipment can be assured.
z Driving the cabinet combining clock.
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3.2.2 Architecture and Principle
I. Principle of Temperature Monitoring
TCU controls the 220 V AC input from the external power supply, the +24 V DC output
of the storage batteries (excluding the power distribution of the air-conditioner) and
the power-on/off commands for some boards according to the temperature of the
cabinet. For the control logic of TCU, refer to Figure 3-2.
TCU
TRX/CDU
Storage battery
220V AC
controlsignals
Figure 3-2 TCU control logic
TCU takes different measures to protect the main equipment at different temperature
control points. Look at the following example.
If the cabinet operates at the initial temperature of -20C, the main equipment works
in protection state. The air conditioner/heat exchanger will be working, but some non-
BCCH carrier power amplifier will be closed. Specific number of power amplifiers to
be closed can be configured through BSC data configuration. In this case, no power
supply will be input for the PSU.
If the temperature control device is started and the temperature goes higher until -5C,
the main equipment will exit the protection state, the PSU will be powered on and
some non-BCCH carrier power amplifiers that have been closed will be re-started.
When the temperature rises to +60C, the main equipment will enter protection state
again and the system power supply will be cut off, including PSU and storage
batteries.
Similarly, when the temperature goes down to +50C, the main equipment will re-exit
the protection state. When the temperature goes down to -15 C, the main equipment
will enter the protection state again.
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II. Principle of Driving Cabinet Combining Clock
TCU performs the driving distribution of the cabinet combining clock and the match
setting of the control signal CBUS1. Figure 3-3 shows the principle of driving the
cabinet combining clock.
TMU 1 2 3 4 TRB
5 6
When TCU is installed in main
cabinet, here outputs the second
clock source.When TCU is installed in extension
cabinet, here receives the clock
from main cabinet.
When TCU is installed in maincabinet, here outputs the first clock
source.TCU
Figure 3-3 Principle of driving cabinet combining clock
Warning:
When the TCU powers off or is replaced, all other boards power off and the servicesare interrupted.
3.3 EMUA
3.3.1 Performance Index
I. Compatible with 24 V, 48 V, and 60 V power input
z For 24 V power input, the voltage range shall be 18 V30 V;
z For 48 V power input, the voltage range shall be 42 V60 V;
For 60 V power input, the voltage range shall be 48 V72 V
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II. Supporting Active/Standby RS422 Serial Port and RS232 Serial Port for
Debugging Purpose
Primary serial port 1 is connected to BTS according to BTS O&M Low-speed Link
Protocol or CDMA EMU (Environment Monitoring Unit) Protocol. RS232 serial port
share a common physical interface with standby RS485 serial port.
3.3.2 Functions
Main functions of EMUA are listed as follows:
I. Mornitoring Basic Enviornment Parameters of BTS
EMUA can collect the following data:
z The temperature and moisture
z Watering
z Access control
z Intrusion
z Smoke
The collection items can be enabled or disabled by DIP switch.
You can also use the DIP switch to select alarm level for watering, intrusion, smoke,
and extended Boolean value.
The threshold value of the temperature alarm is - 20C + 80C. The threshold value
of the moisture alarm is 0% 99%.
Note:Temperature alarm, moisture alarm, and watering alarm are immediate alarms. Anti-
theft alarm and smoke alarm are retainable alarms, and such alarms can only recover
after you manually delete them. Ensure all the alarms can be shielded from the
hardware.
II. Detecting Voltage of Power Supply
Range of detection: 18 V 72 V. Accuracy: 1%.
You can set the threshold of voltage alarm from MPU of BTS. If the MPU does not
deliver the threshold of voltage alarm, you can judge it from the detected voltage in
following criterion:
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z If the detected voltage is not less than 36 V, then the power supply is regarded
as 48 V power input. In this case, the upper threshold is 57 V, and the lower is
42 V (defaulted in 48 V system).
z
If the detected voltage is less than 36 V, the power supply is regarded as 24 Vpower input. In this case, the upper threshold is 28 V, and the lower is 20 V
(defaulted in 24 V system).
III. Automatic Resetting when Communication Is Broken
EMUA automatically resets 1 minute after the normal communication between host
and EMUA is broken. If EMUA does not communicate with the host after power-on,
such resetting will not occur.
IV. Checking 32 Extended Boolean Values
1) You can access 8-channel extended Boolean value to passive main contact point
signals or DC active signals by selecting hardware. The rest 24-channel
extended Boolean value can only be accessed to passive main contact point
signals
2) Collectors (sensors) for external passive main contact points can be mutually
isolated or connected through common end.
3) EMUA can decide the level is high or low.
z If the amplitude of DC active signal is 5 V26 V, then the signal is a high
level;,
z If the amplitude of DC active signal is 0 V1 V, then the signal is a high
level;
z If the amplitude of DC active signal is 1 V5 V, then the signal can be
decided to either high level or low level
4) The output level of Boolean value extended interface must be clearly defined and
have definite identification. The 16 mandatory Boolean values include eight 12 V
extended Boolean value input channels (Channel 0Channel 7) and eight 24 V
extended Boolean value input channels (Channel 8Channel 15). Among the
12 V channels and 24 V channels, there are respectively two accessible positive
signals..5) The 16 optional Boolean values include eight 12 V extended Boolean value input
channels (Channel 16Channel 23) and eight 24 V extended Boolean value
input channels (Channel 24Channel 31). The channel identification is printed on
the silk screens inside the chassis.
V. Configuring Lightning Protection Panel with 32-channel Boolean Value to
Protect Inputted Signals from Lightning
Nominal discharging current of lightning protection panel is 15 KA (8/20s surge
current). An Outdoor Boolean value signal shall pass the lightning protection panel
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before it accesses EMUA. In this way, alarm box can avoid the port damage or
incorrect alarm caused by surge current of outdoor signal because the lightning
protection panel can endure 15KA 8/20s of surge current for 10 times. EMUA has
EAC lightning protection panel. The protection level can reach 15 KA for commonmode and differential mode, residual voltage 75 V for the line-line and line-ground.
VI. Four Extended Analog Collection Channel
The input analog quantity can be current signals at 4 mA20 mA or voltage signal at 0
V5 V.
VII. Six Relay Output
The output of relay is conducted through telecommunication commands. The contact
point capacity of relay is 1A/ 30V DC. Every relay provides constantly open and
constantly closed contact points.
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Chapter 4 Temperature Adjustment System
4.1 Overview
The heat dissipation and heating under low temperature of outdoor BTS3012A are
accomplished by the temperature adjustment system. The temperature adjustment
system has high reliability performance and reports alarms when faults occur. The
temperature adjustment of BTS3012A is accomplished by the air-conditioner or heat
exchanger.
4.2 Air Conditioner
BTS3012A is a complete outdoor BTS with enclosed cabinet architecture. When the
cabinet works at a high temperature, the internal temperature of the cabinet will go up
quickly so that the cabinet cannot work normally, because the large amount of heat
generated by the cabinet itself cannot be dissipated due to the enclosed architecture.
To reduce the internal temperature of the cabinet, the air-conditioner is installed in the
front door of the cabinet to dissipate heat. The air-conditioner will form a temperature
close loop to monitor and control the cabinet internal temperature. When the air-conditioner detects low temperature in the cabinet, it will start its internal heating
boards and the inner circling fans to provide heating to the cabinet. When high
temperature is detected, the air-conditioner will start cooling function to keep the
working temperature in the cabinet within normal working range. In this way, the
cabinet can work reliably in both high and low temperatures.
The technical specifications of the air-conditioner are listed below:
z Rated voltage: 220 V AC ! 10%
z Rated frequency: 50/60 Hz ! 3 Hz
z Heating power: 2600 W
z Refrigerating power: 1600 W
z Working temperature: -55C to +55C
4.3 Heat Exchanger
The heat exchanger is the other option to control the internal temperature. It
incorporates a simple design with a dry contact closure each for high temperature
alarm and low temperature alarm. The heat exchanger sets up a closed loop and
provide heat dissipation capacity when the maximum internal temperature is greater
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than the maximum external temperature, Compared with air conditioners, heat
exchangers typically use fewer, higher reliability components, and have a less
complicated design, all at a lower cost.
The technical indices of the heat exchanger are listed in the following:
z Rated voltage: 220 V AC ! 10%
z Rated frequency: 50 Hz ! 3 Hz
z Heat exchanging power: 500 W
z Heating power: 2700 W
z Working temperature: -55C to +45C
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Chapter 5 Transmission Mode
BTS3012A supports multiple embedded transmission modes as described below:
z Reserving a space with standard 5U high and 19-inch wide for installing the
transmission device.
z Providing 1-channel 24 V power supply or 1-channel 220 V power supply
z Providing 4-channel 48 V power supply when equipped with TSU
z Reserving cable outlets for embedded microwave and SDH
This chapter describes the E1 transmission and SDH transmission networking modes
for BTS3012A.
5.1 E1 Transmission
The E1 networking of BTS3012A supports star, tree and chain networking modes
according to the actual deployment of a site.
I. Star Networking
Star networking applies to common deployment. Each site can be connected to its
BSC directly via E1 links. Therefore, star connection mode enjoys simple networking,easy and convenient maintenance, engineering and capacity expansion. In star
networking mode, signals travel through fewer parts and the line reliability is high.
However, it requires greatest amount of transmission links among all the networking
modes. Therefore, star networking is usually applied to densely populated cities.
Figure 5-1 shows the star connection of BTS3012A, where each single line
represents one channel of E1 link.
BSC
BTS3012A
BTS3012A
BTS3012A
Figure 5-1 E1 star networking of BTS3012A
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II. Tree Networking
In tree mode, the networking is rather complicated. Signals travel through more parts
and the line reliability is low. This makes engineering and maintenance more complex.
Faults in the upper level site might affect normal operations in the lower level site. Re-
constructing the whole network might be done for capacity expansion. However, it
requires less transmission links than star networking. Therefore, tree networking is
usually applied to large areas with low population density.
Note that the levels of site signals traveling from BSC are limited. Usually, the series
connection of sites cannot exceed 5, or we can say, the depth of the tree cannot
exceed 5, because the BTS clock generally takes the phase lock of its upper network
and each phase lock will bring along the degradation of clock quality.
Figure 5-2 shows the tree networking of BTS3012A, where, each single linerepresents one channel of E1.
BSC BTS3012A
BTS3012A
BTS3012A
Figure 5-2 E1 tree networking of BTS3012A
III. Chain Networking
In chain networking mode, signals travel longer and the line reliability is poor.
Therefore, chain networking can be applied to strip-shaped areas with low population
density, such as the area along railways and subways. In such areas, chain
networking can better meet users' requirement and greatly reduce the amount of
transmission equipment required. Similar to tree networking, the number of node
series connected under chain networking cannot exceed 5.
Figure 5-3 shows the BTS3012A chain networking, where each single line representsone or multiple channels of E1.
BSC BTS3012A BTS3012A
Figure 5-3 E1 chain networking of BTS3012A
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IV. Ring Networking
In ring networking mode, the reliability of the site is high. When a BTS on the front
part of the transmission chain is power off or faulty, this networking mode ensures the
following BTSs works normally.
In normal status, the BTSs forms a common chain connection in the sequence as
BTS1, BTS2, BTS3 (ring direction). If any one of the nodes is broken, the networking
mode of the BTSs before this node remains the same. The ones after this node form
a new chain in the reversing sequence (anti-ring direction).
The advantage of ring networking over chain networking is that when one BTS is
down, the other BTSs can keep working normally by splitting the chain into two new
chains. This increases the reliability of the system.
BTS1 BTS2 BTS3
BSC
A B C D
Figure 5-4 BTS E1 ring networking
5.2 SDH Transmission
If SDH transmission equipment is installed, BTS3012A can support SDH transmission.
When deciding the chain connection or ring connection for SDH networking, you have
to take into consideration the actual distribution of network routes. Usually, ring
connection is adopted, because it has high self-healing capability as long as there is
appropriate route distribution. While for the areas along railways and subways, chain
connection is usually adopted.
5.2.1 Ring Networking
Ring networking has high self-repairing capability. When an optical fiber gets
damaged, ring network can repair itself into a chain network, and the service will not
be affected. Figure 5-5 shows the ring connection for SDH networking, where each
single line represents one or multiple channels of E1 and each pair of lines represent
one pair of optical fibers.
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BSC BTS3012A BTS3012AOpticaltransceiver
Figure 5-5 SDH ring networking of BTS3012A
5.2.2 Chain Networking
Figure 5-6 shows the SDH chain networking, where each single line represents one
channel of E1 and each pair of lines represent one pair of optical fibers.
BTS3012A BTS3012ABSCOptical
transceiver
Figure 5-6 SDH chain connection of BTS3012A
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