Content uploaded by Manjish Adhikari
Author content
All content in this area was uploaded by Manjish Adhikari on Aug 08, 2016
Content may be subject to copyright.
Vol. 16 | July 2015 ISSN-4265-0578
Journal of The International Association of Advanced Technology and Science
A Survey and Review of GSM Base Transceiver System
Installation, Architecture and Uplink/Downlink
Manjish Adhikari
B. Tech Senior year, Department of Electronics and Communications Engg.
Jawaharlal Nehru Technological University, Kakinada, A.P, India
adhikari.manjish@gmail.com
No. 01 www.jiaats.com JIAATS-JEEE
Abstract
With the advent of development in LTE
system, eNodeB the revolutionised version of
BTS is used for a connection between BSC
and the users. A better and improved system
increases the capacity and the functionality of
the mobile wireless communication system. A
Base Transceiver System (BTS) is a system in
a mobile communication network that houses
radio receivers and is used for wireless
communication between users and network
providers that is under the control of Base
Switching Controller (BSC) and then the
exchange. This paper deals with the study of a
ground based GSM Base Transceiver System
(BTS) and it’s installation process,
architecture, internal structures, the process
involved in the uplink and downlink call
procedures and the future works. This study
is based on the visit to a ground based BTS at
BSNL regional training centre (RTTC),
Hyderabad during the EETP course. The
observations made are duly recorded,
reviewed and presented for a better
understanding of a mobile BTS system.
Keywords: BTS, BSC, GSM, LTE, Prefab shelter,
Baseband signal, Uplink, Downlink,
I. OVERVIEW
A mobile network consists of Mobile Station
(MS), Base Station Subsystem (BSS), Network
Switching Subsystem (NSS) and Operator
Support Subsystem (OSS) .The Base Station
subsystem is divided into two parts- BSC and
BTC. A BTS, also referred to as the radio base
station (RBS), node B (in 3G Networks) or,
simply, the base station (BS) or evolved node
eNB in LTE standard is a system that has the
radio transceivers which define a cell and
provides wireless communication between users
like mobile phone, computers or WLL phones
and a network service provider. A BTS is
controlled by a Base Station Controller (BSC). A
BTS is usually placed in the centre of a cell
whose transmitting power defines the size of a
cell. Each BTS has between 1 to 16 transceivers,
depending on the density of users in the cell.
Each BTS serves as a single cell. A BTS has four
main parts namely power element, a power
source (engine/alternator), a BTS machine and
Towers & antenna.
Vol. 16 | July 2015 ISSN-4265-0578
No. 01 www.jiaats.com JIAATS-JEEE
Usually while installing the BTS certain
parameters are to be considered and certain
standard procedures are to be followed.
II. SITE SELECTION
Ground based BTS system should be kept at a
place where RF survey is performed first. There
shouldn’t be any high tension lines around that
could interfere with the signals at the BTS. The
area should have an easy access with the
transport facility so that operation and
maintenance can be easily done. The area
where the BTS is to be installed should be
levelled and with a power source nearby. Power
source, engine alternator, pre fab shelter and
tower foundation site should be selected
properly.
Figure 1- GSM Network
III. BTS/ TELECOM SHELTER
A BTS is a closed chamber which should be
sealed from the external environment and away
from the heat, weather and noise. The shelter
should be light weight and easy to maintain with
the four walls, root, floor and the door, (perfect
sealing). Usually having a dimension of
4000L*3500W*3000H (all in mm). The
temperature within the shelter should be
maintained at 25+/-2’C
Technical Specifications of a Pre fab Shelter
under study
I) Roof structure and cover– Pre-
painted galvanized sheets of 0.4 mm
thick trapezoidal shelter laid over a
framework of truces, columns and
purling.
II) Wall - Providing and fixing of walls
using 50/75 mm thick interlocking
aerated concrete wall panels made
of two 5 mm thick cement fiber
boards conforming to IS 14276-
1995.
III) False ceiling- Using 595*595*12
mm mineral fiber board/gypsum.
Placed on suspended grid frame to
form 600*600 mm grid suspended
ceiling.
IV) Doors- made of pressed steel using
powder coated CR coil 1.25 mm
thick, shutter of 32 mm thick ERP
flush door.
V) Windows- made of pressed steel
using powder coated CR 1.25 mm
Thick C channels of size 30*52 or
77 mm.
VI) Painting- 2 coats of acrylic paint
outside and 2 coats of oil bound
distemper inside.
(Source: BSNL EETP India)
A BTS is usually associated with GSM or
CDMA and is able to encrypt and decrypt
communication signals, spectrum filter and
wirelessly communicate.
IV. ARCHITECHTURE OF BTS
The general architecture of BTS system
reveals the following parts.
A. Power Cards: A power card is used to
provide fixed current and voltage levels
Vol. 16 | July 2015 ISSN-4265-0578
No. 01 www.jiaats.com JIAATS-JEEE
to circuit components. A BTS usually
uses -48V power whose positive is
grounded to reduce noise.
Figure 2- Architecture of BTS
B. Baseband receiver Unit (BB2F): A
BB2F is used for digital signal
processing and frequency hopping. It
connects the BOIA card to TRx.
C. Transceiver (TRx)/ Data Receiver
(DRx): Transceivers handles the user
calls. Usually there are 12 TRx in a BTS
and can handle 8 calls/sec.
D. Base Operation and Interface Unit
(BOIA)- It processes the baseband
signals received from the BB2F and
interfaces the processed signal with
transmission cards such as RRI, E1/T1
etc. Also BTS initialisation, power
amplification, O&M signalling, clock
functions, timing functions, etc. So it is
considered as the brain of the BTS.
E. Radio Receiver Card(RRI) : It
provides E1 connectivity to the BTS.
Also it creates the microwave link
between BTS & BSC.
F. Multicouplers and Duplexers:
Multicouplers are used to connect
different TRxs also into the duplexer.
G. Alarm Extension System : It monitors
and collects the working state of
various units of BTS and then extends to
the O&M monitoring station.
V. TOWERS AND ANTENNAS:
Usually the tower is ground based or roof top
based; roof top based used in the congested city
area. GBT are near the BTS having height of
usually 30-40m. Towers may be self-supporting
or guyed tower. Based on their applications
towers may be of following types-
A. Microwave Towers: They are used for
long distance communication and has
30-100 m height.
B. Triangular Tubular Hybrid
Towers(TTHT): BSNL uses them in
rural areas of 40,60,80 or 100m heights.
Usually it contains 15 m mast; 5 panels
each of 3m height.
C. For GSM technology 40 m high towers
are used. The steel tower material has
legs of M.S. angles of grade A as per IS:
2062-1999 & IS: 808-1989, materials
for nut and bolt are of grade 4.6; The
fabrication of tower was done in
accordance with IS 800-1984.
Figure 3. Antennas in BTS
Vol. 16 | July 2015 ISSN-4265-0578
No. 01 www.jiaats.com JIAATS-JEEE
Similarly two major types of antennas are used
in the BTS. They are:
A. GSM Antenna: It is used for the
transmission and reception of the user’s
signals. It is plane or a dipole antenna.
B. Microwave/Drum Antenna: These are
parabolic or horn antenna. It works
based on Line of Sight propagation
(LOS) and connects BTS to BTS or with
the BSC.
Antennas are usually directional so as to
avoid power loss and more area coverage.
To improve the quality of the signal usually
a process called antenna diversity or space
diversity is employed.
VI.CALL PROCESS THROUGH BTS
Usually the path followed for the call
process in uplink and downlink can be
explained as the flow chart. The information
sent by the mobile users are caught by the
GSM antenna and via a duplexer into the
transceiver which send the information to be
processed by the BB2F. This processed
information through the transmission unit
like antenna is sent to the BSC which
monitors it in the exchange. In the downlink
process, the data stored in the internet or
from other sources are sent to the users via
similar path.
The customers within a cell are connected to
a particular BTS and hence based on the
power and capacity of BTS, customer
number is determined. The BTS includes
amplifiers that supply the appropriate
broadcast RF power levels as well as boost
the incoming RF signal power so that it is
suitable for transmission to the BSC.
Another function of the BTS is to convert
between the appropriate protocols for
broadcast to the wireless portion of the
network or to convert the protocols for
transmission to the BSC.
VII. CONCLUSION
A BTS system is an important part of the
mobile and wireless communication system
that monitors the customers within the cell.
Based on this system the capacity of network
is determined so an effective BTS can result
in high network capacity and better
functionality.
VIII. FUTURE WORKS
With the advent of development in LTE
system, eNodeB the revolutionised version
of BTS is highly efficient. There are a lot of
research opportunities in this area of LTE
which is dedicated to providing faster data
rate and better connectivity.
IX. ACKNOWLEDGEMENT
This study and review is mostly based on the
findings of the visit and training at BSNL
RTTC Hyderabad. I would like send my
sincere gratitude to all teaching staffs of
Vol. 16 | July 2015 ISSN-4265-0578
No. 01 www.jiaats.com JIAATS-JEEE
RTTC who guided us in learning the core
backbone of mobile communication system
and Department of ECE, JNTU Kakinada for
providing the assessment opportunity.
X. REFERENCES:
[1] Satoshi Maruyama, Katsuhiko
Tanahasi, Takehiko Higuchi, Base
Transceiver System for W-CDMA
System
[2] Prefab Shelters and Towers,
learntelecom.bsnl.co.in/EETP/BSNL_SI
LVER_CERTIFICATION_COURSE/VER.0
2/ June 2014
[3] Peng Chenguyan
http://www.dcs.gla.ac.uk/~lewis/teac
hing/Tik-111.html
[4] Base Transceiver Station
https://en.wikipedia.org/wiki/base_tr
ansceiver_system
[5] Fibre Optic Transmitter in Base
Station Application, Avago
Technologies
[6] L.A. Akinyemi, N.T. Makanjuola & O.
Shoewu, F.O. Edeko; African Journal
of Computing and ICT Vol. 7 No.2 June
2014 Comparative Analysis Of Base
Transceiver Station (BTS) and Power
Transmission Lines Effects On The
Human Body In the Lagos Environs,
Lagos State, Nigeria.
[7] Bhargav Shankhalpara; BTS Site Visit
http://www.slideshare.net/bhargav_s
hankhalpara/bts-visit
[8] Nasir Faruk, Mujahid Y. Muhammad,
Olayiwola W. Bello, Abubakar
Abdulkarim, Agbakoba John and
Mohammed I. Gumel ; Energy
Conservation through Site
Optimization for Mobile Cellular
Systems (Base Transceivers Station
Optimization)
[9] GSM Architecture
“www.tutorialsports.com/gsm
[10] Yasir Malik, Kishwer Abdul Khaliq,
Bessam Abdulrazak, Usman Tariq;
Mobile Node Localizations in Local
Network
[11] GNURadio:
http://www.gnu.org/software/gnurad
io
[12] Marco Anisetti, Claudio A Ardagna,
Valerio Bellandi, Ernesto Damiani,
and Salvatore Reale. Advanced
localization of mobile terminal in
cellular network. International
Journal of Communications, Network
and System Sciences.1(1):95–103,
2008.
