Cellular concepts discusses various wireless communication technologies including cellular systems, wireless LANs, satellite systems, paging systems, and personal area networks (Bluetooth). It describes key aspects of these technologies such as frequency bands used, range, data rates, and applications. It also provides details on cellular network architecture and components, GSM network structure, base station subsystem functions, and operation of paging systems.

1. CELLULAR CONCEPTS
AMIT SOROT EC-08007
ADVANCED GROUP OF INSTITUTION

2.  Transmitting/receiving voice and data using
electromagnetic waves in open space.
 The information from sender to receiver is carried over
a well defined frequency band(channel).
 Each channel has a fixed frequency bandwidth &
capacity(bit rate).
 Different channels can be used to transmit
information in parallel and independently.

3. Transmitting signal
Received signal
satellite
Transmitting
antenna
Receiving
antenna

4.  FM RADIO 88 MHZ
 TV BROADCAST 200 MHZ
 GSM PHONES 900 MHZ
 GPS 1.2 GHZ
 PCS PHONES 1.8 GHZ
 BLUETOOTH 2.4 GHZ
 Wi-Fi 2.4 GHZ

5.  Freedom from wires.
 No bunch of wires running from here and there.
 “Auto Magical” instantaneous communication without
physical connection setup e.g.- Bluetooth, Wi-Fi.
 Global coverage
 Communication can reach where wiring is infeasible
or costly
 e.g.- rural areas,buildings,battlefield,outerspace.
 Stay connected,flexiblity to connect multiple devices.

6. RADIO TRANSMISSION:- easily generated, Omni-
directional , travel long distance , easily penetrates
buildings.
 PROBLEMS:- frequency dependent , relatively low
bandwidth for data communication , tightly licensed by
government.
MICROWAVE TRANSMISSION:- widely used for long
distance communication , give high S/N ratio , relatively
inexpensive.
 PROBLEMS:- don’t pass through buildings , whether and
frequency dependent.

7. INFRARED AND MILIMETER WAVES:-
widely used for short range communication , unable to
pass through solid objects , used for indoor wireless
LANs , not for outdoors.
LIGHT WAVE TRANSMISSION:- unguided optical
signal such as laser , unidirectional , easy to install , no
license required.
PROBLEMS:- unable to penetrate rain or thick fog , laser
beam can be easily diverted by air.

8.  CELLULAR SYSTEM
 WIRELESS LANs
 SATELLITE SYSTEM
 PAGING SYSTEM
 PANs(BLUETOOTH)

9. Definition
 Wireless communication
technology in which several
small exchanges (called cells)
equipped with low-power radio
antennas (strategically located
over a wide geographical area)
are interconnected through a
central exchange. As
a receiver (cell phone) moves
from one place to the next,
its identity, location, and
radio frequency is handed-over
by one cell to another without
interrupting a call.
Practical

10.  High capacity is achieved by limiting the coverage of
each base station to a small geographic region called a
cell.
 Same frequencies timeslots/codes are reused by
spatially separated base stations.
 A switching technique called handoff enables a call to
proceed uninterrupted when one user moves from one
cell to another.
 Neighboring base stations are assigned different group
of channels so as to minimize the interference.

11.  By systematically spacing base stations and the
channel groups may be reuse as many number of times
as necessary.
MSC
CELLS
PSTN
SUBSCRIBER
UNIT
BASE
STATIONS
Coverage
area

12. BSC
BS1
BS2
BS3
Connect to Bs1 & start
calling
Out of BS1 coverage &
connect to BS2
Out of BS2 coverage
& connect to BS3
Call
ended

13.  Cellular radio systems rely on intelligent allocation and
reuse of channels throughout the coverage area.
 Each base station is allocated a group of radio channels
to be used within the same geographical area of its cell.
 Neighboring base stations are given different channel
allocation from each other.
 The design procedure of allocating channel groups for
all of the cellular BS within a system is called
frequency reuse or frequency planning.

14. Co
channel
cells
Co channel
cells

15.  Co channels
60 degree
u
v
D

16.  Axes u and v intersect at 60 degree.
 Unit scale is the distance between center cells.
 If cell radius to point of hexagon is R then 2Rcos30=1
 Or R = 1/√3. to find the distance of a point P(u , v)
from the origin we use x-y to u-v coordinate
transformation.
 R² = x² + y²
 x=ucos30˚
 y=u+vsin30˚
 r=√(v²+uv+u²)

17.  Using this equation to locate co-channel cells we start
from reference cell and moves i hexagon along u axis
then j hexagon along the v axis.
 Hence the distance between co-channel cells in
adjacent cluster is given by D = √(i²+ij+j²)
 The number of cells in a cluster N is given by
 N = √(i²+ij+j²) where i and j are integers.
 Hence the possible values of N are 1 , 3 , 4 , 7 , 12……

18.  Formation of cluster for N=7
 Suppose i=2 and j=1 will give co channel cell
 Same color showing co-channel cells.
i=2
j-=1
Co channel
cells

19.  Global system for mobile communication is a set of
ETSI standards specifying the infrastructure for a
digital cellular services.
 GSM networks are structured hierarchically it consist
of one administrative region which is assigned to a
MSC.
 Each administrative region is made up of at least one
location area (LA). LA is also called the visited area.
 An LA consists of several cell groups.
 Each cell group is assigned to a base station controller
(BSC)

20. GSM NETWORK
MSC REGION
LOCATION AREA (LA)
BS CONTROLLER
CELL CELL
LA
LA
BS
CONTROLLER
BS
CONTR
-OLLER
MSC
REGION
MSC
REGION

21. BSC
MSCEIR
AUC
HLR VLR
ISDN
PSTN
OTHER
NETWORKSBSS
NSS NMS
Mobile
station

22.  Consist of two main elements.
 1. The mobile equipment
 2. Subscriber identity module(SIM).

23.  BSS = BSC + BTS
1. RADIO PATH
CONTROL
2. AIR INTERFACE
SIGNALLING
1. CENTRAL N/W
ELEMENT OF BSS
2. CALL
ESTABLISHMENT
3. MOBILITY MGMT
4. STATISTICAL
RAW DATA
COLLECTION
1. SPEECH
PROCESSING
2. MODULATION/DE
MODULATION
3. TRANSCODER
4. MINIMIZE
TRANSMISSION
PROBLEM
5. AIR INTERFACE
MANAGEMENT

24.  NSS = MSC + HLR + VLR + AUC + EIR
MANAGE
COMMUNICATION
B/W USERS
INCLUDE
DATABASE TO
STORE
INFORMATION
OF USER
CALL
CONTROL
MOBILITY
MGMT
SUBSCRIBER
DATA
HANDLING
CHECK
IDENTITY OF
USER
PERMANENT
STORAGE OF
USER
INFORMATION
STORE
A COPY
OF HLR
CHECK
ROAMI
NG
PROVIDE
AUTHENT
ICATION
SECURITY
CHECK
IMEI
NUMBER
OF
MOBILE

25. 1. MONITORING
2. MANAGE
3. OPERATION
4. MAINTANENCE
NMS

26. USE TDMA + FDMA
MODULATION USED = GMSK(Gaussian minimum
shift keying)
UPLINK FREQUENCY = 890 – 915 MHZ
DOWNLINK FREQUENCY = 935 – 960 MHZ

27.  WLAN connect local computers
 Range (100 m) confined region
 Break data into packets
 Channel access is shared
 Backbone internet provides best service
 Poor performance in some application like videos
 Low mobility

28.  Global coverage
 Different orbit height
 Optimized for good transmission
 Expensive base stations.
 Voice and data transmission
 Telecommunication application
 GPS , global telephone connection
 TV broadcasting , military , whether broadcasting

29.  Broad coverage for short messages
 Message broadcast from all base stations
 Simple terminals
 Optimized for one way transmission
 Answer back hard
 Overtaken by cellular
Pager system

30. PSTN
Paging
control
center
Paging
terminal
Paging
terminal
Paging
terminal
Terrestrial link
Terrestrial link
Satellite
link
City 1
City 2
City N
Base
station
Base
station
Base
station

31.  Bluetooth
 Cable replacement RF technology
 Short range(10m)
 2.4 GHz band
 TDD duplex scheme
 1 Mbps data rate shared b/w 7 devices
 Polling based multiple access
 Work on frequency hopping spread spectrum
technology

32.  Peer to peer communication
 No backbone infrastructure
 Routing can be multihop
 Topology is dynamic
 Fully connected with different link SINRs.

33.  Ad-hoc network provides a flexible network
infrastructure for many emerging applications.
 The capacity of such networks is generally unknown.
 Transmission , access and routing strategies for these
networks are generally ad-hoc.
 Cross layer design is very critical and challenging.
 Energy constraints impose interesting design for trade
offs communication and networking.