A

QUICKGUIDE FOR

RF &

BTS OPERATIONS(PROVIDING QUICK GUIDE ON PDH TRANSMISSION LINK AND BSS INTEGRATION FOR

FIELD GUYS)

PREPARED BY AGBANA, TEMITOPE (MTNN)

1

Chapter 1. Introduction

Installation Overview

RADIO LINK INSTALATION STEPS

Hardware Installation Pre-Installation Installation Antenna Alignment Customer supplied tools and equipment Unpacking the equipment Verifying the system configuration Check basic components Check kits and accessories Antenna ODU (OUTDOOR UNIT) ODU grounding ODU cable Cable running and fastening Fitting and weatherproofing connectors Cable grounding Lightning surge suppressor INDOOR UNIT RADIO EQUIPMENT plug-in cards Traffic and NMS cables Options EOW AC power supply

SOFTWARE INSTALLATION & CONFIGURATION Connect PC and logon Check status Configure Power on Align the antenna RSSI at the ODU or, RSL indication on your Thinclient

2

OUTDOOR INSTALLATIONS

This chapter describes the following installation procedures:

• Installing the Antenna• Installing the ODU• Installing ODU Cables and Connectors• Installing Lightning Surge Suppressors• Weatherproofing

Installing the Antenna

Antennas must be installed in accordance with the manufacturer’s instructions.

• For direct-mounted ODUs the antenna includes a collar with integral polarization rotator. Dependant on frequency band, these antennas are available in diameters up to 1.8 m (6 ft).

• Where standard antennas are to be used, the ODU must be installed on a remote-mount, and a flexible waveguide used to connect to the antenna. Before going to the site, check that you have the required installation tools as recommended by the antenna manufacturer, and that you have the antenna polarization and initial pointing data.

• For direct-mounted ODUs, polarization is determined by the setting of the polarization rotator.• For standard antennas, polarization is determined by the orientation of the antenna.

Installing the ODUAll ODUs are designed for direct-mounting to a collar supplied with direct-fit antennas. ODUs can also be installed with standard antennas using a remote-mount kit.

3

For single-antenna protected operation a coupler is available to support direct mounting of the two ODUs to its antenna, or to support direct mounting onto a remote-mounted coupler.

Direct-Mounted ODUsThe ODU is attached to its mounting collar using four mounting bolts, which have captive 19 mm (3/4”) nuts for fastening.

The ODU mounts directly to its antenna mount, as shown in Figure 1-1 shows an ODU directly mounted on the antenna. The pressed-collar ODU can be seen mounted on the mounting collar.

Fig 1-2 shows radio waves pole mount andMounting collar of an eclipse radio.

Setting the PolarizationThe polarization of the transmitted signal, horizontal or vertical, is determined by the position of the polarization rotator fitted within the ODU mounting collar.The ODU is then mounted on the collar to match the chosen polarization.The rotator is an integral part of the antenna mount. The default setting is for vertical polarization.If the rotator is not set for the required polarization, you must adjust its orientation. This topic describes the adjustment procedures for Radio Waves and Andrew antennas.

4

Procedure for Radio Waves RotatorThe polarization rotator is fixed by three metric Allen-head bolts.

To change the polarization of the Radio Waves antenna:1. Loosen the bolts. Refer to Figure below.2. Rotate to other end of the slots. Refer to Figure 1-3.3. Check bold heads are located in the slot recesses.4. Refasten.

Figure below shows a close-up of the polarization rotator being released from the vertical position (left) and rotated clockwise towards horizontal (right).

Figure 1-3. Radio Waves Polarization Rotator

Procedure for Andrew RotatorTo change the polarization of the Andrew antenna:

1. Release (do not completely undo) the six metric Allen-head screws approximately 10 mm (3/8 inch). Pull the collar forward and hold the rotator back, which will allow the rotator to disengage from a notch in the collar, and turn freely.

2. Turn the rotator hub 90° until it locates back into a notched “timing recess” in the collar.

5

3. Check that the timing mark on the rotator hub has aligned with either a V or an H on the collar to confirm polarization. Ensure the rotator hub is correctly seated within its collar, then push the collar back against the antenna mount and re-tighten the six screws.

Note that the ODU must be mounted on the Antenna to match the polarisationCorrect positioning for vertical or horizontal polarization is shown in the figure shown below.

6

Remote-Mounted ODUsODUs can be installed separate from its antenna, using a remote-mount to support the ODU, and a flexible-waveguide or coaxial cable to connect the ODU to its antenna:

• For 6 GHz ODUs and above, a flexible waveguide is required.• For 5 GHz ODUs, a low-loss coaxial cable is required. The remote mount allows use of standard, single or dual polarization antennas.

Picture showing the flexible waveguide.

Flexible waveguides are frequency band specific and are normally available in two lengths, 600 mm (2 ft) or 900 mm (3 ft). Both flange ends are identical, and are grooved for a half-thickness gasket, which is supplied with the waveguide along with flange mounting bolts.

7

To prevent wind-flex, a flexible waveguide or coax must be suitably fastened or supported over its length. Where it is not possible to fasten directly to the support structure, hanger assemblies are recommended, comprising a stainless steel clamp, threaded rod and a form-fit rubber grommet. Figure 2.1 shows a typical assembly.

Figure 2-1. Flexible Waveguide Hanger Assembly

8

ANTENNA ALIGINMENT

PreparationBefore aligning antennas ensure:

• The ODUs are powered up at both ends of the link.• Transmit and receive frequencies are correctly set.• Transmit powers are correctly set and transmit mute is turned off.

If frequency and/or power settings are not correct for the application, interference may be caused to other links in the same geographical area. Hence it is very important to ensure that the frequency implemented is in direct consonance with the design on the WA.Alignment via your thinclient.For details on Portal login and the use of Portal for installation and commissioning, refer to the volume IV Portal.As Portal is accessed via connection to the INU or IDU, a separate means of communication such as two-way radio or cell phone is required between the Portal operator and the person at the antenna.

The alignment process includes the following steps:

1. Monitor RSL with your thinclient.2. Adjust the antenna alignment for maximum RSL.3. Repeat for the far end of the link.

9

4. Compare actual RSLs with the expected RSLs from the link installation design. Measurement accuracy is nominally ± 2 dB.

Alignment using the RSSI Voltage at the ODUA voltmeter, such as a multimeter, is used to measure the RSSI voltage available at the BNC connector on the ODU. A suitable BNC to banana-plug connecting cable is available as an optional ODU accessory.

To align using the RSSI voltage at the ODU:1. Connect the voltmeter to the BNC connector. Center pin is positive. Use a low voltage range for best resolution, nominally 2.5 Vdc FSD.2. Adjust antenna alignment until the voltmeter reading is at minimum value.3. Repeat for the far end of the link.4. Check and record the peak voltage at each end. The RSSI voltage provides a direct relationship with RSL. An RSSI of 0.25 Vdc ≡ -10 dBm RSL, and each additional 0.25 Vdc RSSI increase thereafter corresponds to a 10 dBm decrease in RSL, as follows:5. Compare actual RSLs to the expected RSLs from the link installation design. Refer to RSL Measurement Guidelines.6. Replace the BNC weatherproofing cap.

RSL Measurement Guidelines

The RSL measured should be within ± 4 dB of the predicted value(± 2 dB for transmit, ±2 dB for receive). For any greater discrepancy, it is recommended that the antennas are realigned and if necessary, the path calculations checked or the path resurveyed.A discrepancy of 20 dB or greater between the measured and calculated RSLs indicates that an antenna is aligned on a side lobe, or there is a polarization mismatch.

Units MeasurementBNC (Vdc) 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25 2.5RSL (dBm) -10 -20 -30 -40 -50 -60 -70 -80 -90 -100

Aligning the Antenna

10

Antenna alignment involves adjusting the direction of each antenna until the received signal strength reaches its maximum level at each end of the link.Fine adjustment for azimuth (horizontal angle) and elevation (vertical angle) is built into each antenna mount. Adjustment procedures will be provided with each antenna.If the horizontal adjuster does not provide sufficient range to locate the main beam, the antenna mounting brackets will need to be loosened and the antenna swiveled on its pole mount to locate the beam. Before doing this, ensure the horizontal adjuster is set for mid-travel. Some mounts for larger antennas have a separately clamped swivel base to allow the loosened antenna to swivel on it without fear of slippage down the pole. Where such a mount is not provided atemporary swivel clamp can often be provided using a pair of pipe brackets bolted together immediately below the antenna mount.

Locating the Main BeamEnsure the antennas are aligned on the main beam, and not a side lobe.Once a measurable signal is observed, very small alignment adjustments are required to locate the main beam. For instance, a 1.2m antenna at 23 GHz typically has 0.9° of adjustment from center of main beam to the first null (0.4° to the -3 dB point). Antenna movement across the main beam will result in a rapid rise and fall of signal level. As a guide, 1 degree of beam width is equivalent to moving approximately 1.0 mm around a standard 114 mm (4.5 in.) diameter O/D pipe.Antennas can be verified as being on main beam (as opposed to a side lobe) by comparing measured receive signal level with the calculated level.Signal strength readings are usually measurable when at least a main beam at one end and first side lobes at the other are aligned.The strongest signal occurs at the center of the main beam. The highest first lobe signal is typically 20–25 dB less than the main beam signal. When both antennas are aligned for maximum main beam signal strength, the receive signal level should be within 2 dB of the calculated level for the path. This calculated level should be included in the installation design for the link.

11

Figure 5-1 on page 5-8 is an example of a head-on, conceptual view of the beam signal strength, with concentric rings of side lobe peaks and troughs radiating outward from the main beam.

CONFIGURATION AND TROUBLESHOOTING RADIO EQUIPMENT USED IN THE MTNN NETWORK

PDH RADIO EQUIPMENT INCLUDES:

MINILINK E TRAFFIC NODE

SDH RADIO INCLUDES:

ALTIUM DXR HARRIS MEGASTAR HARRIS STRATEX (ECLIPSE) HARRIS TRUEPOINT

MINILINK –E TRAFFIC NODE

This section gives a brief overview of MINI-LINK E Traffic Node and its components.

12

Traffic Node is an indoor concept for sites with several radio link connections.The system provides cost-effective and intelligent functionality for traffic routing, multiplexing as well as mechanisms for equipment, propagation and network layer protection.One single magazine holds the indoor parts of the medium capacity radio terminals and other plug-in units providing E1, E2, E3 and STM-1 interfaces.The modular system enables new interface units to be added while in operation. This hot insertion of new plug-in units and automatic software upgrade ensure that traffic is operational during replacement and functional upgrade. Software controlled traffic routing minimizes cabling, while co-sitting features make integration with existing MINI-LINK E installations easy.

The first aspect of the traffic node that we will be looking at is the ACCESS MODULE MAGAZINE (AMM).The AMM houses the plug-in units and provides backplane connection for the plug-ins.

There are four standard types of plug-in unit:

Node Processor Unit (NPU) Line Termination Units (LTU) for E1 and STM-1 traffic respectively Modem Unit (MMU2)

In addition there are specific plug-in units for AMM 6p and AMM 20p and they are:

Power Filter Unit (PFU2) Fan Unit (FAU2) Power Filter Unit (PFU1)

Power Filter Unit (PFU)The PFU is a power and filter unit supplied by -48 V. One unit for each Traffic Node is required but for AMM 20p it is recommended to use two units, together with two power supply sources.

Node Processor Unit (NPU)

13

The NPU 8x2 is the central controller in Traffic Node and has two E1 connectors (8xE1), one User I/O connector and one 10/100BASE-T connector. One NPU 8x2 is always required in each Traffic Node.

Line Termination Unit (LTU)The line termination unit provides traffic interfaces and it comes in three different versions:

• LTU 16x2 has four E1 connectors with a total of 16xE1.• LTU 155e is a terminal multiplexer with an electrical STM-1 interface for Connection to SDH networks.• LTU 155e/o has the same functionality as LTU 155e but also has an additional optical STM-1 interface. Only one type of connection is possible at the same time.

Modem Unit (MMU2)MMU2 is the modem unit, interconnected with the radio unit using a single coaxial cable. It is available in two versions; MMU2 4-34 which is software configurable from 2x2 up to 34+2 (17x2) Mbit/s, and MMU2 4-8 which is software configurable to 2x2 or 4x2/8 Mbit/s.

IntroductionThe Traffic Node can operate in different modes providing different functions when working with the LCT. Below follows a short description of the different modes.

Node Installation ModeThis mode is used for initial setup of the Traffic Node, allowing a limited set of parameters to be set. It is also used for some specific maintenance procedures.

The Traffic Node is accessed using a default IP address (10.0.0.1) and the PC (and the FTP server on the PC) obtains a dynamic IP address (10.0.0.2) from a DHCP server in the Traffic Node. This means that the PC should be configured to use dynamic IP addressing. However, using the static IP address 10.0.0.2 on the PC will also work.

14

One of the major problems encountered by RF/BTS Operation Engineers is the inability to access the traffic node due to change in the default IP addresses. When access to the TN equipment is not possible, then diagnostic troubleshooting wont be possible. To get around this however, an erricson USB LAN driver has been released and this will help the field guys connect to the TN with their USB LAN cable.

Follow the procedure below carefully and you will find your way into the TN equipment regardless the IP address running on it.

Install your Ericsson USB LAN software on your computer Connect your USB LAN Cable to the TN radio equipment Follow the prompt by clicking ‘next’ button until the installation is

finished Right click on your ‘network places’ and click on properties

Right click on the Ericsson USB LAN Connection Click on properties as shown below

Figure TN 1:

15

The following menu will show on your configuration screen:

16

Highlight the Internet Protocol (TCP/IP) Click on the ‘use the following IP Address’ and input the following

parameters:

IP address: 10.0.0.2Subnet Mask: 255.255.255.0

The above process is to enable you put your thinclient on the same IP Range as the TN equipment so that they could communicate with each other.

17

Highlight the Internet Protocol (TCP/IP) and click properties.

Click Ok. Close the LAN properties menu.

To confirm if you are connected to the Traffic Node Radio you can do the following:

Go to start Click on ‘Run’ Type ‘cmd’ takes you to command prompt

18

Type ‘ping 10.0.0.1 -t’

If you have a reply as shown below, then you are connected to the TN

equipment.

To log on to the equipment then you must use the web interface:

Open your internet explorer Click on tools Click on internet options Click on connections Click on never dial a connections Click on LAN Settings Uncheck Proxy Server Close the LAN Settings Page Type the following: http://10.0.0.1

19

Enter user name: control_user Password: ericsson

Default user name and password are used for the Traffic Node.Looking on the left hand side pane of the diagram we can see all of the Plug-ins listed above:Such that:

FAU2 1 PFU3 1/1 MMU2 C1/2 MMU2 C1/3 NPU1 B 1/7

You can extend the + beside the MMU2 C1/3 and NPU1 B1/7, and thus start your configuration process.

20

The MMU2 C1/3 Alarm Status on the right hand side displays all the alarms on the Radio Terminal Unit.The RF input from the antenna through the RAU N 23/95 High Power gets into the MMU as an IF signal.The output power is the transmit power designed on the WA and the input power is the Receive Signal Level.If the link is effectively set up then both ends of the terminal will be inview...And if there is a problem with the link, then the far end of the terminal will not be in view.

Understanding the Menus in Normal ModeThe menu commands in Normal Mode are described below.

• Fault — the fault displays a sub-menu with fault commands and allows you to view the alarms on the Traffic Node Equipment.Alarms and Status — Opens the Alarms and Status page for an entity where you can view alarm and status information. Alarm List — Opens the Alarm List page where you can view all active alarms for the Traffic Node or a single plug-in unit. Event Log — Opens the Event Log page for the Traffic Node where you can access alarm and event information in the Event Log. • Configuration — Displays a sub-menu with configuration commands.Configuration — Opens the Configuration page where you can configure an entity. All E1 Configuration — Opens the All E1 Configuration page for an LTU 155, LTU 16x2, NPU 8x2, MMU2 or SMU2 (co-sitting). The page is used to configure all E1 interfaces on the plug-in unit simultaneously.

21

The snap above shows the first page on the traffic node log on.. The MMU2C is on position 6 on the AMM and the green indicator clearly depicts that plug in is running very fine. Directly facing the MMU2C is the RAU in its green state and this implies that the RAU is also running without hitch.The Red Indicator or the NPU connotes that there is a problem on the Node Processor Unit.The problems encountered on the NPU are subdivided into two viz:

Hardware Software

Hardware: this occurs when there is a hardware failure…some of the hardware failures are caused by the following:

22

Erratic power supply Manhandling of the NPU Bent pins on the AMM Electrostatic High temperature

Software: the most common software problem arises as a result of E1 ConfigurationThe figure below shows the alarm status for the NPU1 B1/7 The Unit Status clearly shows that the Unit is working fine.The E1 status shows critical alarm and this is a clear indication that the unit is not carrying traffic at all.To solve this problem, you must ensure that the E1 is getting through to the site from the Hub. It is not enough for the E1 to get through to the site, it is very crucial to ensure that the traffic routing is done so that the E1 will be configured for use.

23

CONFIGURING THE TRAFFIC NODE EQUIPMENT

To configure the Traffic Node Radio, follow the procedure below: Click on the MMU2 C1/3 icon on the left hand pane Click on the configuration on the right hand pane Under the configuration click on configuration again On the near end ID input the site ID Address Check the notification end box Input the far end site ID address Check the radio ID box (if this is unchecked then the link is

susceptible to interference) Check activate traffic button Input the traffic capacity –Modulation as designed (be sure that they

are exact at both ends) Select (1+0) protection mode if you are setting an unprotected link

and a (1+1) for a protected link Input your BER alarm threshold as designed in the WA Input the fade notification timer as designed in the WA

24

Check the in service button Notifications

CONFIGURING THE TRANSMIT AND RECEIVE FREQUENCIES ON THE MMU

Click on the RAU2 N HP 1/3.1 and the configuration page shown below will become visible and then you input the parameters on the WA.

25

Check the in service box on top Input Transmit Frequency on the WA (remember that transmit freq is

the receive on the far end and vice versa) Check the transmitter box on Input the output power mode as designed Input output power from the WA Max power output power is on MAX by default Target input power for far end is on -30dBm RF input alarm threshold in dBm is inputted based on designed

When the right parameter is inputted and the antennae are rightly aligned then the far end will come into view and the received level could be

26

monitored and measured with the WA. Proper alignment will help achieve the best receive level.

CONFIGURING THE TRAFFIC NODE TO CARRY TRAFFIC

The link may be well set up with fantastic receive levels, but if the TN is not configured to carry traffic then all work done will equal zero.

Quick way to configure the traffic node to carry traffic:

Click on the triangle on the top of the left plane Click on configuration on the right pane Click on traffic routing Select the NPU1 B1/7 on the right and the MMU2 C 1/3 on the left Then click on routing Check the boxes in between the NPU and the MMU In the right pane you can see the triangle with MBC and on the right

pane you click on configuration until you see the traffic routing. On clicking on the traffic routing you will see the ‘select interface’ On the interface type select E1 On the select units for interface views, select MMU2C 1/6 On the X-

axis and NPU1 B1/7 on the Y-Axis Select matrix view

27

This mapping takes the dip straight to the chrome block and from the chrome block to the RBS cabinet or to another radio link as the case may be.

In certain situations where the LTU (Line Terminal Unit) is used, you need to map the LTU to the MMU in similar manner to the above.

28

COMMON FIELD PROBLEMS ENCOUNTERED WITH THE TRAFFIC NODE RADIO

It is very important to note that the Traffic Node Radio is temperature and power sensitive and so it is imperative that you keep steady power at site and also ensure that the environment is good enough for the equipment to operate at its best.

HARDWARE

BENT PINS ON THE BACKPLANE: if this occurs on the MMU backplane, then you be sure that you will not be able to input your configuration parameters because the everything on the configuration page will be passive thus inhibiting your ability to input your designed configuration parameters.

BAD MMU: A bad MMU may not even come up at all i.e. the power LEDs will not come lit up, all you need do is just to replace the MMU Plug-in.

29

BAD NPU: A bad Node processing unit will prevent you from logging on to the Traffic Node Radio. Note no technical work can be done on the Radio if the NPU is down because your access to other plug-ins will be impossible.

Check the diagram below to see my experience of a bad NPUAll I did to bring up the TN equipment proved abortive until I changed the NPU.Mind you, when you change the NPU, you will have to do your traffic routing all over again else, the E1’s will be unusable at site.

CONNECTORS: A bad RF Connector can prevent communication between the RAU and the MMU and when there is a failure between the RAU and the MMU then connectivity the far end and the near end terminal will be lost.The Connectors must be dirt and water free at all times and you must ensure that there is no bridge between the positive and the negative.

30

Note: the core copper metal in the center is the positive and the gauze surrounding it is the negative.

BAD RF CABLE: A Bad RF Cable line will prevent the flow of power from the MMU to the RAU and when the RAU is down then communication can not be established between the two ends.

BAD TERMINATION: When the cables are badly terminated, then you must be sure that your link will certainly develop problems.

BAD RAU: A bad RAU will certainly bring down the link… of course, their will be nothing to configure when the RAU is bad. All you can do is to replace the RAU, but you must ensure that you get the RAU type for instance (23/95) is an RAU type and it has a pair it matches with.A mismatch in the RAU type will compound your problems in your effort to resolve an existing fault so do ensure that in the process of investigating your link failure, ascertain the specification of the RAU and get the Match for it and its accurate size.If the size is not put into consideration, then be sure that you may have to go to the site with a waveguide etc.

SOFTWARE FAULTS ON THE TRAFFIC NODE

31

the picture above is a capture of an MMU running on a wrong software…the effect of this is that the configuration page becomes very passive and it is absolutely impossible to input the transmit and receive frequency. Obviously, the transmitter will remain off, and the input power which is the receive level will be too minute to carry signal. Therefore, the far end can never be in view hence the link will remain down and down until the MMU is replaced.

Furthermore, a software reset may be needed on the MMU when it is not responding to the RAU..Note that before you do a reset on the MMU, you need to capture the configuration parameters existing because as soon as you do a reset, you will loose the whole configuration and the only alternative will be to drive down to the far end to get the parameters or call the TX Planning guys to get you the WA.

32

MINILINK E RADIO EQUIPMENT

This PDH is easier to maintain and more user friendly but less intelligent than the Traffic Node.

The Minilink E comprise of the MMU or and an SMU depending on the application.

To configure the Minilink E, follow the procedure given below:

Log on to the MMU with your thinclient with your DB-9 RS 232 Connect your DB-9 Cable to the Minilink Equipment Connect the other end to your thinclient Open the MSM (Minilink manager) software Click on Network on the top left Click on Scan Local (this displays the equipment on the AMM on the

right hand pane) Click on the topmost address (the topmost address is the address of

the minilink you are directly logged on to) Click on setup on your top left

If you have indeed the procedures as stated above, you will have a picture on your laptop similar to what is shown below.

33

The picture above displays what you have on both ends of the link i.e. the near end and the far end terminal.On the blue line on top of the picture is the address of the minilink address you are working on.MLE_1+0 clearly depicts that it is a non-protected link…The alarms page displays the alarm status on the MINILINK E plug-insWe have three core components viz:

1. The MMU2. The RAU3. The SMU (This is optional as it depends on the application )

An alarm on any of the equipment will indicate on the specific equipment and clicking on it will take you to a menu that will interpret the problem and proffer possible solution to the fault indicated. This feature makes the minilink more interactive and user friendly.

34

The figure below is a typical example of an alarm on the MMU. If you click on the red button, you will find direction on what the problem is all about and what you need to fix it.

CONTROL AND STATUS On the control and status menu, you have the TX and RX button where you have the transmit and receive parameters displayed.

BASE STATION SYSTEM INTEGRATION (BSS INTEGRATION)

BSS OVERVIEWThe base station controller (BSC) controls and supervises the radio resources in the Base Transceiver Station (BTS). Together with the BTS,

35

the BSC constitutes the base station system BSS, responsible for the management and cell configuration data of the radio network.

The main functions of the BSC are

Administration of BSS resources Supervision of the BTS Connection handling of mobile stations Locating and handover Transmission of network management Operation and maintenance of the BSS

Note: the transcoder perform the speech conversion from 64kbit/s into a total of 16k or 8k, 13+3kbit/s and 15.1+0.9kbit/s (full rate and enhanced speech coder, FR and EFR)

The BSS consists of a BSC and a BTS. The BTS is the radio equipment which transmits and receives information over the air to allow the BSC to communicate with MSs in the BSCs service area. A group of BTSs is controlled by a BSC.The BSC has the functionality to set up, supervise and disconnect circuit-switched and packet-switched calls. It is a high capacity switch that provides functions including handover, cell configuration data and channel assignment.

RBS OVERVIEW

The RADIO BASE STATION includes all radio and transmission interface equipment needed on a radio site.

The TRANSMISSION RADIO INTERFACE is logically part of the BSC but physically located in the RBS. It forms a digital cross-connect function, which makes it possible to switch 64kbps time slots or channels on a PCM link to time slots towards a radio transceiver

CASCADE CONNECTION The essence of a cascade connection is to save transmission cost if there is spare cpacity on the PCM link, connected to the transit TRI.

CONNECTION OF TIMING GROUP (TG)

36

One TG is normally synonymous with one BTS, that is, one TG connected to one cell or a sector.There must be a TRX in the TG for each pair of radio carrier frequencies (uplink and downlink) that constitute a radio channel allocated to a cell.A TRX is part of one TG. The TRX contains most of the equipment required to transmit and receive on that radio channel. The communication between the TRX and the BSC is switched through the TRI. A TG handles functions that are common to a number of TRXs (16 Max.)

These functions include:

Timing module (TM) Transceiver controllers (TRXC) Transmitters (TX) Receivers (RRX) Time Slots (TS)

RBS 2000 SERIES HARDWARE ARCHITECTURE

The hardware comprises a number of replaceable units (RUs) and buses. The RU is the smallest hardware part that can be replaced when performing rpair at the site, this may be a TRU (Transceiver Unit), cable, fan etc.

The DXU (DISTRIBUTION SWITCH UNIT)

The DXU (Distribution Switch Unit) is the RBS central control unit. It provides a system interface by cross connecting either a 2Mbit/s or 1.5Mbit/s transport nework or individual time slots to their associated transceivers.

The DXU is divided into four main sections.

PCM-part, represents the managed object Interface Switch (IS) and the Digital Path (DP)Note: the Digital Part (DIP) is the name of the function used for supervision the connected PCM lines.

Central Processing Unit (CPU), Represent the Managed object Central Function (CF)

37

Central Timing Unit (CTU) represent the managed object Timing function (TF)

High level Data Link Controller (HDLC) concentrator, represents the managed object concentrator (CON)

Their main functions are:

The aim of the PCM-part (IS) is to extract time slots from the A-bis Link and pass them to the TRUs over the local bus. It is possible to connect two PCM lines (Port A/B) to the DXU.This is seldom done to increase the capacity or to offer redundancy on the transmission links.

The IS can drop time slots which are not used in the RBS, to another destination. This is called Multi Drop (Cascading) and it enhances flexibility.Up to five RBSs can be interconnected on a PCM line from the BSC. The incoming time slots are connected to PCM port A on the DXU. The outgoing time slots towards the next RBS are connected to PCM, Port B.

The CPU carries out the resource management within the RBS in addition to that, it is responsible for:

RUs software loading and storage Interface to the OMT Operation and Maintenance Internal and external alarms Extraction of LAPD signaling information.

The HDLC concentrator enables the features LAPD concentration that increases the capacity of a PCM line toward the RBS.

TRANSCEIVER UNIT (TRU)The TRU is a transmitter/receiver and signal-processing unit, which broadcasts and receives the radio frequency signals that are passed to and from the mobile station. Each TRU handles eight air time slots.The TRU includes all functions related to one radio carrier supporting eight Basic Physical Channels (BPC) on a TDMA frame. The functions include:

38

Radio transmitting Radio receiving Air interface signal processing TRX management

TRU is divided into three main sections:

Transceiver Unit Digital (TRUD) represents the managed object Transceiver Controller (TRXC)Transmitter Block (TX-block)Receiver Block (RX-block)

Their main functions are:

The TRUD serves as the TRX controller. It interfaces with other RBS components via the Local Bus, CDU Bus, Timing Bus, and X Bus. The TRUD performs uplink and downlink digital signal processing, such as channel coding, interleaving, ciphering, burst formatting.

The transmitter Block performs the downlink signal modulation and amplification. Additionally, the Transmitter Block performs Voltage Standing Wave Ratio (VSWR) Supervision. That is basically a quote of the power sent and the power reflected back during transmission. To supervise this gives an indication if something has happened to the antenna system, for example, the feeder is damaged.

The Receiver Block performs the uplink signal modulation and the routes the demodulated signal to the TRUD part.

COMBINING AND DISTRIBUTION UNIT (CDU)

A combiner is a devise, at the base station that allows for the connection of several transmitters to one antenna. It allows each transmitter RF energy out to the antenna, while blocking the RF energy from other transmitters utilizing the same antenna. There are two combiner types:

Hybrid Filter

39

The CDU is the interface between the TRUs and the antenna system. The main purpose of the CDU is to reduce the number of antennas used in each cell/sector.

The CDU’s hardware functions are:

TX combining RX pre-amplification and distribution Antenna system supervision support RF Filtering

The CDU combines or distributes the transmitted signals from various transceivers and distributes the received signals to all transceivers.The same antennas are used for transmitting and receiving, if a duplex filter is used. All signal are filtered before transmission and after reception by means of band pass filters. A measuring coupler unit is included, providing forward and reflected power measurements for voltage standing wave ratio calculations in the TRU.

ENERGY CONTROL UNIT

The ECU controls and monitors the power and climate equipment to regulate the power and the environmental conditions inside the cabinet to maintain system operation. It communicates with the DXU over the local bus. The main unit os power and climate system are:

Power Supply Units (PSU) Battery Fuse Unit (BFU) AC Connection Unit (ACCU) Fans controlled by Fan Control Units (FCU)

LOCAL BUS The local bus offers internal communication between the DXU, TRU and ECU. Examples of information sent on this bus are TRX signaling, speech and data.

TIMING BUSThe timing bus carries air timing information from the DXU to the TRU’s

40

CDU BUSThe CDU Bus connects the CDU to the TRUs and facilitates interface and O&M functions, for example, transfers alarms and RU specific information.

X-BUSThe X-Bus carries speech/data on a time slot basis between the TRUs. This is used for base band frequency hopping.

THE REPLACEABLE UNIT MAN MACHINE INTERFACE.

The main Machine Interface implemented in the RBS comprises visual indicators (LEDs) and operation control switches.The main and sub RUs have at least one red and one green LED indicator. The green LED indicates that the RU is operational and the red LED indicates that a fault has been detected in the RU.The lit red LED on the RU provides a means of recognizing the faulty RU after opening the RBS door, and can be replaced without using any specialized tools

There are other switches for enabling local or remote operation on the Distribution Switch Unit (DXU) and Transceiver Unit (TRU). When in the local mode the RBS or portions of it, is disconnected and isolated from the BSC, whereas in the remote mode the BSC has control of the RBS. Switching the DXU into LOCAL mode results in automatic blocking of the entire RBS, whereas switching a TRU into LOCAL mode results in automatic blocking of only the affected TRU. This operation does not disturb any other TRUs operations.

OPERATION AND MAINTENANCE TERMINAL (OMT)

Operation and Maintenance Terminal (OMT) is a software tool specifically designed for the RBS 2000 family of base stations.It is used to perform a number of operation and maintenance tasks on site or remotely from the BSC. OMT is used during the Radio Base Station (RBS) testing process, both in the warehouse and on-site.It is used updating and maintaining the RBS installation database (IDB), defining RBS external alarms, and during the performance of preventive and corrective maintenance functions on the RBS 2000. The primary functions that OMT will be used to perform are; monitoring the cabinets

41

Internal Alarms in the troubleshooting process, performing IDB operations, defining the External Alarms and Antenna Related Auxiliary Equipment and monitor the hardware and configuration status of the RU’s in the cabinet.

INTERNAL ALARMS

During the base station repair process, the Monitor function can be used to collect the information about the fault status of the RBS.This will provide the engineer with the ability to check for faults when no MMI indications are present and to confirm repair actions after an RU has been replaced.

INSTALLATION DATABASE

Each RBS has a built-in Installation database where information about installed hardware is stored. This provides a way to maintain an actual inventory list of all hardware installed. The database can be accessed by the OMT. IDB information is permanently stored in the flash memory of all main RUs and sub RUs. IDB information pertaining to passive RU’s must be manually entered and is retained in the DXU (Central Main RU).

TG-HARDWARE FOR RBS 2000

DXU- Distribution Switch Unit Functions

CF: Central Function, is the control part of a TG, it is an SW function, handling common control functions within a TG.The BSC communicates with the CF using layer 2 LAPD, and is addressed by its TEI =62. However, it is possible to use a different TEI addressing other than the default. CON: LAPD Concentrator is used by the optional feature LAPD Concentration for RBS2000

IS: Interface Switch, provides a system interface to the PCM links and cross-connects individual time slots to certain transceivers.

TF: Timing Function extracts synchronization information from the PCM link and generates a timing reference for the RBS.

42

DP: Digital Path, Layer1 reception and transmission are not part of the BTS Logical model. However, each of the PCM systems terminating in the TG has an associated supervision object, the DP.Reports of transmission faults and supervision of transmission quality are carried over the A-bis O&M interface. That is signaling is described using managed object, the DP.

TRU- TRANSCEIVER UNIT FUNCTIONS

TRXC: Controlling all the functions for signal processing, radio receiving, and Radio Transmitting.Each TRX corresponds to one TRU unit and is addressed with a TEI value (0-11), depending on the TRU physical position.

The BSC currently supports a maximum of 1,020 TRXs

TX: The MO representing the transmitter functions, for example, transmitted power and frequency on the bursts sent.

RX: The MO representing the receiver functions.

TS: All timeslots are represented by MO TS.

GUIDE TO LOADING INSTALLATION DATABASE (IDB) ON YOUR RBS

Connect your cable DB 9 cable from your thinclient to your RBS Open the OMT programme

The graphic user interface shown below appears.

43

Click on the arrow on the left hand corner to connect to the RBS Click on the book on the 4th position on the top left hand corner to

read the IDB Click on the configuration menu on the topmost top Click on create IDB

(the menu below appears)

44

On the cabinet set up, click new

Drop the cabinet type folder menu select 2206 Drop the power system and select +24VDC or -48VDC as the case

may be Click ok

45

Click New on the Antenna Sector Setup Click New on the Antenna Systems for Sector 0 Under frequency, select (GSM 1800 or 900) as the case may be On the CDU type, select the CDU type physically seen on the RBS Duplexer is on YES by default1

TMA is NO TX Combining, select Hybrid Combiner, Filter Combiner or

Uncombined RX antenna sharing select No by default RX Diversity selects 2-Way by default Click ok Repeat same process for Sector 1 and Sector 2 Click ok

1Document Prepared by Agbana, Temitope (MTNN)

46

DEFINING THE PRESENT RU’s2

2Document Prepared by Agbana, Temitope (MTNN)

47