DRU Unit Description

DESCRIPTION

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Copyright

© Copyright Ericsson AB 2006–2009. All rights reserved.

Disclaimer

No part of this document may be reproduced in any form without the writtenpermission of the copyright owner.

The contents of this document are subject to revision without notice due tocontinued progress in methodology, design and manufacturing. Ericsson shallhave no liability for any error or damage of any kind resulting from the useof this document.

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Contents

Contents

1 Introduction 1

1.1 Revision Information 1

2 Product Overview 2

2.1 Main Functions 2

2.2 Variants 2

2.3 Size and Weight 3

2.4 Power Consumption and Heat Generation 3

3 Function Description 3

3.1 CPU System 5

3.2 DSP System 5

3.3 Radio Control System 5

3.4 Radio System 5

3.5 Combiner and Distribution System 6

3.6 Filter System 6

4 Interfaces 6

4.1 Signal and Power Interfaces 6

4.2 Operator Interface 7

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DRU Unit Description

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Introduction

1 Introduction

The Double Radio Unit (DRU) is a replaceable unit containing two Transceivers(TRX). It is the interface between the Y links and the antenna system. Thefigure below shows DRU variants.

P015621F

OperationalRF offLocalLocal/Remote

Fault

DRUReset

Uc

DRU

DC in

Y-link TMA PWR1

TMA PWR2

TX/RX1

TX/RX2RX out 1

RX out 2

RX in 2

RX in 1

DRU-02

OperationalRF offLocalLocal/Remote

Fault

DRUReset

DRU

DRU-01

DC in

Y-link TMA PWR1

TMA PWR2

TX/RX1

TX/RX2RX out 1

RX out 2

RX in 2

RX in 1

OperationalRF offLocalLocal/Remote

Fault

DRUReset

Uc

DRU

DC in

Y-link TMA PWR1

TMA PWR2

TX/RX1

TX/RX2

RX out 1

RX out 2

RX in 2

RX in 1

DRU-03

Figure 1 DRU

1.1 Revision Information

Other than editorial changes, this document has been revised as follows:

• Appearance of DRU-03 front supplemented to illustration

• TX combining mode description for DRU-03 added

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DRU Unit Description

• Combiner and distribution system description for DRU-03 added

• DRU-03 phrase supplemented to table note in indicators table

• Indicator label in indicators table changed from Uncomb to Uc

2 Product Overview

The DRU is the interface between the Y links coming from the DistributionSwitch Unit (DXU) and the antenna system. The DRU consists of twoTransceivers (TRX), a combiner and distribution system, and a filter system.The DRU interface also supports both GSMK and 8-PSK (EDGE) modulation.

The DRU has a hybrid combiner that is used to combine the two Transmitter(TX) terminals into one terminal. DRUs can operate in either combined modeor uncombined mode.

Each TX/RX terminal has an in-built bias injector that, when connectedto the Tower-Mounted Amplifier Control Module (TMA-CM), supplies theTower-Mounted Amplifiers (TMA) with power.

2.1 Main Functions

The DRU:

• Transmits and receives Radio Frequency (RF) signals

• Processes signals

2.2 Variants

The following DRU variants are available, depending on frequency band:

• E-GSM 900

• P-GSM 900

• GSM 1800

The following DRU variants are available, depending on the method forselecting TX combining mode:

• DRU-01: TX combining mode is selected using software configuration.

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Function Description

• DRU-02: TX combining mode is selected by changing the position of aswitch card in a card holder slot on the rear of the DRU (see documentChanging Configurations)

• DRU-03: TX combining mode is selected by changing the position of aswitch card in a card holder slot on the rear of the DRU (see documentChanging Configurations)

2.3 Size and Weight

The table below shows the physical characteristics of the DRU:

Table 1 Size and Weight

Height Width Depth Weight

445 mm 90 mm 280 mm 10 kg

2.4 Power Consumption and Heat Generation

The table below shows the physical characteristics of the DRU:

Table 2 Power Consumption and Heat Generation

Maximum Power Consumption Maximum Heat Generation

500 W 445 W

3 Function Description

The figure below shows the DRU block diagram.

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DRU Unit Description

P015651C

CPUsystem

DSP system

Y link

TX ctrlTX dataRX data ARX ctrlRX data B

RC system RXB RXA TX

Radiosystem

Combineranddistributionsystem

HC

Radiosystem

RX data BRX ctrlRX data ATX ctrlTX data

Filter system

DPX

Bias-T

Bias-T

TX/RX1

TMA PWR2

TX/RX2

RX in 2

RX out 1

RXB RXA TX

DPX

DRU

RX out 2

RX in 1

TMA PWR1

A

A

B

B

Figure 2 Block Diagram

The DRU consists of the following main blocks:

• Central Processing Unit (CPU) system

• Digital Signal Processor (DSP) system

• Radio control system

• Radio system

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Function Description

• Combiner and distribution system

• Filter system

3.1 CPU System

The CPU system controls the RBS. It consists of a CPU, support logic, memory,and logic for handling the interfaces.

3.2 DSP System

The two DSP systems perform all the baseband signal processing necessaryfor one TRX. For downlink, this includes Terrestrial Protocol Handling (TPH),encoding, ciphering, and burst generation. For uplink, it includes equalization,combining, decoding, and TPH.

3.3 Radio Control System

The two radio control systems are responsible for the following:

• Synchronizing and controlling the different parts of the radio

• Modulation and Digital-to-Analog (D/A) conversion of the data to transmit

• Filtering the received radio signal with a channel-selective filter

• Compensating the Receiver (RX) and TX delay and gain variations

The RC system is seen by the rest of the RBS as the front end to the radio,which can be asked to transmit a burst of data, using a selected modulation, orasked to receive a burst, using a selected digital filter.

All time critical radio control functions are performed by the RC system and nocomputing support is required from the CPU system on a real-time basis.

3.4 Radio System

Each radio system contains two radio receivers and one radio transmitterincluding power amplifiers.

The radio receiver receives RF-modulated uplink data from one or two diversitybranches and sends it to the RC system.

The radio transmitter generates the RF downlink signal from the modulatedbaseband signal. It then sends the RF signal to the power amplifier, whichamplifies the downlink RF signals.

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DRU Unit Description

3.5 Combiner and Distribution System

The combiner and distribution system handles the routing of the RX and TXsignals between the radio system and the filter system. The hybrid combinerconnects one or two transmitters to one antenna. Depending on the variant, theDRU can be configured by one of the following methods to operate in hybridcombined or uncombined mode:

• DRU-01: Using software controlled relays

• DRU-02 and DRU-03: By manually changing the position of the switch cardin the card holder slot on the rear of the DRU (see document ChangingConfigurations)

The RX signal can be distributed to several other receivers by various switchsettings to minimize the number of RX antennas, for RX sharing, or for 4-WayRadio Diversity (4WRD) configuration.

3.6 Filter System

The filter system filters the TX and RX signals and duplexes them to a commonantenna port. The filter system also contains the bias injectors that providepower supplier to the TMA through the feeder.

4 Interfaces

The operator interfaces of the DRU are described in the following subsections.

4.1 Signal and Power Interfaces

The table below shows the external interfaces of the unit.

Table 3 Signal and Power Interfaces

Interface Description Type ofConnector

DC in Input power to the DRU Male mini-fit

Y link Interface between DXU and DRU Female miniD-sub

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Interfaces

Interface Description Type ofConnector

TX/RX1 Connection to the antenna feeder for TX orTX/RX

Female 7/16

TX/RX2 Connection to the antenna feeder for TX orTX/RX

Female 7/16

RX in 1 RX input from another DRU Female QMA

RX in 2 RX input from another DRU Female QMA

RX out 1 RX output from TX/RX1 to share with otherDRUs

Female QMA

RX out 2 RX output from TX/RX1 to share with otherDRUs

Female QMA

TMAPWR1

Power and control for the TMA connected toTX/RX1

Female QMA

TMAPWR2

Power and control for the TMA connected toTX/RX2

Female QMA

4.2 Operator Interface

The tables below show the indicators and switches of the operator interface.

Table 4 Indicators

Indicator Color

Fault Red

Operational Green

RF off Yellow

Local Yellow

Uc(1) Yellow

(1) DRU-02 and DRU-03

Table 5 Switches

Switch Function

DRU reset Resets the DRU

Local/Remote Local or remote mode

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