lab # 7 engr. mehran mamonai. the double-transceiver unit (dtru) is placed in the...
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CAPACITY PLANNING USING BTS (DTRU)
Lab # 7Engr. Mehran Mamonai
DTRU
The Double-Transceiver Unit (DTRU) is placed in the double-transceiver subsystem of the BTS. One DTRU consists of two TRXs.
DTRU Functions of the DTRU
This descries the functions of the DTRU. The DTRU functionally consists of the baseband processing part, RF transmitting part, and RF receiving part.
Working Environment of the DTRUThis describes the working environment of the DTRU. The DTRUs are inserted into the slots of the backplane in the DTRU subrack.
Working Principles of the DTRUThis describes the working principles of the DTRU. The DTRU consists of the DTRU Baseband and RF Unit (DBRU), DTRU Power Amplifier Unit (DPAU), and DTRU Power Supply Unit (DTPS).
LEDs and Ports on the DTRUThis describes the LEDs and ports on the DTRU panel. There are two types of DTRU: type A and type B. The four LEDs on the DTRU panel indicate the operating status of the DTRU and other functional subsystems. DTRU (type A) has 10 ports and DTRU (type B) has 8 ports. These ports exchanges signals with the RF front-end subsystem.
Specifications of the DTRUThis describes the size, working voltage, power consumption, and weight of the DTRU.
Functions of the DTRU
The DTRU functionally consists of the baseband processing part, RF transmitting part, and RF receiving part.
Baseband Processing Part RF Transmitting Part RF Receiving Part
Working Environment of the DTRU
This describes the working environment of the DTRU. The DTRUs are inserted into the slots of the backplane in the DTRU subrack.
Figure 1 shows the working environment of the DTRU. Figure 1 Working Environment of the DTRU
The working environment of the DTRU is as follows: Receiving clock signals, control signals, and data
signals from the DTRB Modulates the baseband signals into RF signals, and
then transmits the RF signals to the DAFU subrack through RF signal cables
Working Environment of the DTRU
Working Principles of the DTRU
The DTRU consists of the DTRU Baseband and RF Unit (DBRU), DTRU Power Amplifier Unit (DPAU), and DTRU Power Supply Unit (DTPS).
Functional structure of the DTRU
The DBRU is the main functional module of the DTRU. It provides modulation/demodulation, data processing, and combining/dividing between the baseband signals and RF signals.
The DTPS is the power supply board of the DTRU. The DTPS converts the –48 V DC power into +28 V DC power for the DPAU. The DTPS also supplies three routes of power required by the TRX: 8 V, 4 V, and 3.3 V.
The DPAU performs the following functions: Amplifies the signals transmitted from the DBRU to the required
power level Couples the output power for a loopback test and the power detection Provides the detected temperature of the power amplifier Provides wideband combination and PBT functions
Functional structure of the DTRU
Functional modes of the DTRU
RF Transmit Mode Transmit independency mode PBT mode Wideband combination mode Transmit diversity mode
Transmit Independency Mode
The two TRXs work independently without using the combination unit
PBT Mode
One TRX in the DTRU is used. One route of signals goes through modulation
and DA conversion. As these two routes of signals are aligned in
phase, the output power is amplified after combination
Wideband Combination Mode
The two transceivers are combined through a combiner before transmission.
Transmit Diversity Mode
One route of baseband signals are divided into two routes. Thus, the downlink receive level of the MS is improved
Functional modes of the DTRU
RF Receive Mode Receive Independency Mode Receive Diversity Mode 4-way Receive Diversity Mode
Receive Independency Mode
Each TRX of the DTRU uses the main and diversity ports of itself
Receive Diversity Mode
Each main (diversity) signal is divided into two routes through a divider, and then sent to the main/diversity port of the two TRXs. Note only two channels of RF signals are routed into the DTRU through the RF cables
4-way Receive Diversity Mode
Four routes of signals are sent to one TRX. The 4-way receive diversity helps achieve more uplink
gain than the main receive diversity does. Note in the 4-way receive diversity mode, only one TRX
can be used in the DTRU
DTRU Panel
Specifications of the DTRU
Table 1 Specifications for the DTRU (type A)
Item Specifications
Size Size of the front panel (length x width): 389.2 mm x 68.1 mm
Working voltage –48 V power input
Power consumption (heat consumption)
Maximum power consumption with –48 V DC input: 450 W
Maximum power consumption with +27 V DC input: 390 W
Weight 9.2 kg
DAFU subrack
The DAFU subrack can be configured with the DDPU, DCOM
Functions of the DDPU
This describes the functions of the DDPU. The DDPU performs the following functions: Provides lightning protection through the ANT
port Detect VSWR alarms in the antenna system Control the gains for the receive low noise
amplifier Transmits multiple routes of RF signals from the
transmitter to the antenna Receives signals from the antenna, amplifies
and quarters these signals, and then transmits them to the receiver of the DTRU
Working Principles of the DDPU
Functions of the DCOM
The DCOM combines two routes of TX signals from the DTRU, and then sends them to the DDPU.
Working Environment of the DCOM
Assignment
A site is to be configure which serves (a) 92 users, who are present is parliament house. You have to make three sectors. Tell by sketching, how many DTRU cards, DCOM cards and Antenna can be used. Also show connections
(b) 192 users (c) 144 users
Urban (a/b/c) Rural (a/b/c)
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