PREVENTIVE MAINTENANCE (BSS) 

I did my training…..

Ericsson one of Sweden's largest companies, is a provider of telecommunication

and data communication systems, and related services, covering a range of

technologies, including especially mobile networks.

Ericsson is founded in 1876 by Lars Magnus Ericsson and incorporated on august

18,1918

Ericsson has offices and operations in more than 150 countries, with more than

20,000 staff in Sweden, and also significant presences in, for example, the UK,

India, Ireland, the USA, Finland, China, and Brazil.

Ericsson Networks is one of the largest telecommunications solutions suppliers in

the world.

About 1 billion people are connected through its networks.

The world's largest ever manual telephone exchange, serving 60,000 lines, was

installed by Ericsson in Moscow in 1916. Throughout the 1990s, Ericsson held a

35-40% market share of installed cellular telephone systems.

Ericsson is currently the world's largest mobile telecommunications equipment

vendor with a market share of 35%.

GNOC

Front Office

Back Office

Configuration

Management

Operation

Support

Fault Surveillan

ce

Preventive

Maintenance

FaultManagem

ent

  Front office is the first level escalation. Front office

consist of many departments FS, PM,FM.

Surveillance team do live monitoring .They run commands on OSS,see alarm and raise TT forward them to fault management or raise work order to field team as required.

Preventive maintenance do health checkups. They run script and found deviations. Resolve above 80% TT and remaining are transferred to fault management and back office as required.

Fault management do first level troubleshooting and need to clear at least 80% of raised trouble ticket and remaining are forward to the back office and field team as required.

 

Back office is the second level TT not resolved by FO is transfer to it.

 

Configuration management plan and implement the new configure. New tariff is configure by IN and configuration related to BTS is done by BSS.

Operation support maintains the performance of the tools check the security of data system of ericsson. 

What is PM? Preventive Maintenance, as the name suggests, includes

the activities that are meant for the prevention of avoidable outages.

Preventive Maintenance plays an important role in the performance of network as it detect the fault earlier and it is operated before being more challenging. Hence improve network quality.

 

BSS-Base Station Subsystem.

NSS-Network Surveillance System. OSS-Operation system. IN-Intelligent Network.

BSS NSS

OSS

IN

Domains

CUSTOMERS……

PAN INDIA Bharti(15 circle)

DELHI

ETISALAT MUMBAI & IDEA MUMBAI

WHAT PM do……

Taking regular health checkups of the nodes as per the health check list provided by Back Office.

Health checkups divided in two types:• Daily and fortnightly for BSS & NSS Node• Daily & Weekly health checkups for OSS.

Resolve above 80% of the TTs raised by themselves and remaining are being raised to the concerned teams

FAULT MANAGEM

ENT

PREVENTIVE MAINTENANCE WFM

.

IF CRITICAL

Transmission

/ hardware

related problem

TT related to OSS

BACK OFFICE

Health checkup sheet consist of activities in which deviations are found, commands and path for checking and solving the problem, standard output and deviated output.

For BSS they run commands on citrix tool using command handling application. If the output is different from the standard one than it is considered as deviation and a Trouble Ticket is raised for it. Most of Trouble ticket raised is solved on priority basis.

• These are those issues which have critical impact on the network service with high brunt on customer’s business and should be resolved within 4 hour.

CRITICAL

• These are those issues that have on impact on the network services or event which may lead to emergency.These have to be resolved within 10 hour .

MAJOR• These are those

issues that have minor impact on the network services. These have to be resolved within 32 hours otherwisw SLA breached.

MINOR

Advantages of preventive maintenance

Solves above 80% of the raised trouble ticket.

Maintain the better performance of cellular network.

Plays major role in load sharing.

Prevents major/critical issue before they appear and maintains a healthy network.

BASE STATION SUBSYSTEM

BTS: BASE TRANSCEIVER STATION

BSC: BASE STATION CONTROLLERTC: TRANSCODER

BASE TRANSCEIVER STATION (BTS)

• BTS has a set of Transceivers (TRXs) to communicate with mobiles in its area.

• One BTS covers one or more than one cell.• The capacity of a cell depends on number of

transceivers in the cell.• BTS is connected to the BSC through Abis

Interface which is 2Mbps.• BTS transmits and receives voice at 13kbps

over air interface to the mobiles.• BTS performs encoding ,decoding ,time

synchronization ,modulating and feeding signals to the antenna.

BASE STATION CONTROLLER (BSC)

Provides all the control functions and physical links between the MSC and BTS.

External Interfaces ‘Abis’ interface towards the BTS ‘A’ interface towards the MSC

BSC manages the radio resources for one or more BTSs.

It handles radio channel setup, frequency hopping, and handovers.

TRANSCODER (TC) FUNCTIONALITY

BTS

BSC MSC

13 kbps 16 kbps 16 kbps 64 kbps

TC

Base Station Subsystem performs following

functions…….

FREQUENCY REUSE

A3

C2B1

B3

A2C1

C3

B2A1

A3

C2B1

B3

A2C1

B3

A1C1

A1

A3A2

C3

B2A1

A3A3

C3

C1

B2A1B2A1

A2C1

B3

one group includes 3 sectors /site ,9 frequency which are

distributed to 3 sites. Every site owns 3 frequency.

LOCATION UPDATE

Location update is nothing but to update the present location of a Mobile Station (MS) into VLR (Visitor Location Register) of MSC.

There are two procedures: IMSI attach IMSI detach

HANDOVER

Between 1 and 2 – Inter BTS / Intra BSC

Between 1 and 3 – Inter BSC/ Intra

MSCBetween 1 and 4 – Inter MSC

2 types of HANDOVER…..SOFTThis type of

handover is used in CDMA technology.

In this type of handover, the MS first make one link with BTS then break the present link with BTS. So, “make before break” technology is used in soft handover.

HARDHard handover is

implemented in GSM. In this type of handover,

the MS first make break link with BTS A then make the present link with BTS B. So, “break before make” technology is used in hard handover.

The chances of call drop is more in hard handover than soft handover.

CONCLUSION

During this summer training, I built a good understanding of GSM technology that is being widely used by the mobile operators worldwide.

Except the technical learning, I have also learnt a lot about the core values that are being followed at Ericsson which are Respect, Professionalism and Perseverance.

As a part of BSS Preventive Maintenance team I have also seen the criticality of the faults that occur in network and learned the seriousness and discipline with which these faults should be handled.

Having done this training at ERICSSON INDIA PVT LTD., Gurgaon has added a lot my technical and personal skills

QUERIES??