Summer training at bsnl including WLL , cdma gsm technology etc

1. Seminar on Practical Training at
BSNL
Presented by:
Ayush Anand
B.Tech , ECE , 7th Sem
Sri Balaji College of Engineering &Technology, Jaipur
“Telecommunication”

2. Introduction
• 4th largest telecommunication company in Asia and 7th largest in the world.
• Provides GSM and basic telephony service and first company in India
providing 3G technology.
• More than 3 lacs of employees, officers and engineers are working at
present.
Glimpse at Company Profile

3. WHAT IS WIRELESS ?
The word wireless is dictionary defined “having
no wires ” .
In networking terminology , wireless is the
term used to describe any computer network
where there is no physical wired connection
between sender and receiver, but rather the
network is connected by radio waves and or
microwaves to maintain communications.
Wireless networking utilizes specific
equipment such as NICs and Routers in place of
wires (copper or optical fibre).

4. Multiple Access Schemes
• Frequency Division Multiple Access (FDMA)
• Time Division Multiple Access (TDMA)
• Code Division Multiple Access (CDMA)
3 orthogonal Schemes:

5. Frequency Division Multiple Access
• Each mobile is assigned a separate frequency channel for the
duration of the call.
• Sufficient guard band is required to prevent adjacent channel
interference.
• Usually, mobile terminals will have one downlink frequency band
and one uplink frequency band
• Different cellular network protocols use different frequencies

6. Time Division Multiple Access
• Time is divided into slots and only one mobile terminal transmits
during each slot.
• Each user is given a specific slot. No competition in cellular network

7. Code Division Multiple Access
• Use of orthogonal codes to separate different transmissions
• Each symbol of bit is transmitted as a larger number of bits using
the user specific code – Spreading
• Bandwidth occupied by the signal is much larger than the information
transmission rate
• But all users use the same frequency band together
Orthogonal among users

8. Evolution of Cellular Networks
1G 2G 3G 4G2.5G

9. GSM architecture
Global System for Mobile Communication
Services
Architecture

10. GSM Services
• Voice, 3.1 kHz
• Short Message Service (SMS)
• 1985 GSM standard that allows messages of at most 160 chars. (incl.
spaces) to be sent between handsets and other stations
• Over 2.4 billion people use it; multi-billion $ industry
• General Packet Radio Service (GPRS)
• GSM upgrade that provides IP-based packet data transmission up to
114 kbps
• Users can “simultaneously” make calls and send data
• GPRS provides “always on” Internet access and the Multimedia
Messaging Service (MMS) whereby users can send rich text, audio,
video messages to each other
• Performance degrades as number of users increase
• GPRS is an example of 2.5G telephony – 2G service similar to 3G

11. GSM Frequencies
• Originally designed on 900MHz range, now also
available on 800MHz, 1800MHz and 1900 MHz
ranges.
• Separate Uplink and Downlink frequencies
• One example channel on the 1800 MHz frequency band,
where RF carriers are space every 200 MHz
1710 MHz 1880 MHz1805 MHz1785 MHz
UPLINK FREQUENCIES DOWNLINK FREQUENCIES
UPLINK AND DOWNLINK FREQUENCY SEPARATED BY 95MHZ

12. Architecture of GSM

13. Network subsystem
Performs call processing and subscriber
related functions. It includes:
MSC: Mobile Switching Centre
HLR: Home Location Register
VLR :Visitor Location Register
AuC: Authentication Centre
EIR: Equipment Identity Register
GMSC:Gateway MSC.

14. The functions carried out by the MSC are listed below:
Call Processing
Call Switching
Operations And Maintenance Support
Internetwork Networking
When the MSC provides the interface with the other networks
in the GSM network it is known as a Gateway MSC.
Mobile Switching Centre

15. Subscriber ID (IMSI & MSIN).
Current location of subscriber.
Subscriber status
(registered/unregistered)
Authentication key and AUC
functionality.
Mobile subscriber roaming number.
Home Location Register

16. • Provides local database for subscriber when they are away from
home.
It contains:
• Mobile status(busy/free/no ans)
• Location area identity(LAI)
• TMSI AND MSIN .
Visitor Location Register

17. • Provides authentication and encryption.
• Ensures confidentiality of each cell.
• Protects network operators from frauds.
• Associated with HLR.
• Takes place each time the subscriber initializes” on
the system.
Authentication Centre

18. • Centralized database for validating the IMEI
(International Mobile Station Eqipment Identity).
• It contains three lists-
White List
Black List
Grey List
Eqipment Identity Register

19. Base Transceiver Station
• Maintains air interface and
minimize transmission
problems.
• Radio level power control.
• BTS identification.
• Ciphering (Encryption).
• Speech processing.

20. Base Station Controller
It is connected to MSC.
Controls one or more BTS.
Switches traffic and
signaling to/from BTSs and
MSC.
Controls handover
performed by BTS.
Frequency allocation and
power control.

21. • A leased line is a telecommunications path between two
points that is available 24 hours a day for use by a
designated user (Individual or company).
• These leased lines can carry data, voice and video
information. It is not shared in common among multiple
users as dialup line.
DEPARTMENT : MLLN

22. DEPARTMENT : C-DOT
• It stands for Center for Development of Telematics
• Digital Telephone Exchange runs on this technique
• Call processing of Landline Networks
• STD / ISD / LOCAL

23. DEPARTEMNT: Transmission
• Optical fiber communication
• Splicing
• Detection of faults
• Rectification

24. Thanks for your attention !
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