Mobile Communication
Introduction
Dr. Chandimal Jayawardena

Personal Communication

What People Want?

Terminal Mobility

Terminal Mobility
• Mobile terminal can access telecom services
from any location
y
• Locate & identify the terminal as it moves
• Associated with wireless access
– User should carry a wireless terminal
– Sh ld be within radio coverage area
Should b i hi di

Terminal Mobility
• Communication is always between the
terminal and the network
• Call delivery, Billing etc. based on terminal
identity (Mobile Station Number)

Personal Mobility
• Dynamic association between the terminal
and the user
• Personal Number assigned to the user
• Access to network from any terminal
y
• Mobility across multiple networks
• Applicable to wireline and wireless
networks

Service Portability
• Network will provide subscribed services to
a terminal or location designated by the user
g y
– Achieved through ‘IN’ concepts
• User’s service profile is in a database
User s
• User can access, modify & manage his
subscribed services.
services

Trends: My Terminal
• Everybody has his/her wireless personal
terminal
• Multi-purpose terminals for multimedia, internet
access, banking video email
access banking, video, email, electronic shopping,
shopping
entertainment, etc.
• Personal terminal contains all parts which you
have to carry with you: organizer, keys, papers,
electronic money, etc.

Trends: My Services
• Always online
• Services need to be
– Location based
• Next petrol station
– Context aware
• Art exhibition – additional information

Trends: Entertainment
• Music
• Interactive game with a
g
computer or with
another person
p
• Video on your mobile
phone

Trends: Bluetooth
• My phone is the
gateway
• My personal
environment
• Identification
• Local networking

Trends: Advertising on Mobile
Phones
Customers who
agree to accept
advertisements may
receive ads.

Advantages of Wireless
• Constant connection
• Access to up to date information
up-to-date
• Minimum installation issues
• Freedom to roam
Fd
• Scalability
• No cables
• Extensibility e.g remote areas with
eg
satellite

Disadvantages of Wireless
• Careful planning of network essential
• Environment generally hostile
• Security
• Safety
Sf
• spectrum licenses
• poor data rates
• cost (domain dependant)

Some Historical Developments
Origins debatable but ….
– 1887 - Hertz demonstrates EM waves
– 1896 - Marconi demonstrates wireless telegraph
apparatus
pp
– 1901 - First radio signal across the Atlantic (Cornwall
to Newfoundland)
– 1914 - Fi wireless voice transmission
First i l i ii
– 1946 - PSTN augmented with wireless
– 1947 - Cellular Network proposed

Why Cellular?
• Originally proposed by D. H. Ring in an
DH
unpublished paper.
• Why?
– Potential for existing systems to expand was
severely limited
limited.
• How?
– Reuse frequencies so as to maximize the use
of the available radio spectrum thus
improving scalability
scalability.
Note: This issue will be revisited when the GSM architecture is discussed.

Communication Growth Trends
• Mobile technologies will take precedence over
fixed communications technologies
• Data and multimedia applications will take
precedence over voice
• High-speed access will be enabled by the
convergence of many technologies
– Fixed (wireless / wireline)
– Mobile (wireless)

Mobile Technologies

1G - Characteristics
• Analogue transmission technology
• Pioneered semiconductor and microprocessor
technology
• Focus on voice
• Data services almost non-existent
• Incompatible standards
p
– Different frequencies and signaling
– International roaming impossible
• Inefficient use of the radio spectrum

1G - NTT
• Nippon Telephone & Telegraph (NTT)
– Now NTT DoCoMo
• 1979
• Tok o
Tokyo
• World’s first operational cellular system

1G - NMT-450
• Nordic Mobile Telephone 450
• 1982
• Sweden
• First i l
Fi wireless communications standard
ii dd
deployed in Europe
• Pioneered the use of light portable handsets
• Supported international roaming
pp g

1G - AMPS
• Advanced Mobile Phone System (AMPS)
– 1982
– USA
– Developed by AT&T and Motorola
• Mandated (FCC) as the standard to which
all operators in the USA had to adhere to
to.

1G - TACS
• Total Access Coverage (TACS)
• 1985
• UK
• Adaptation of AMPS
Ad i f
• Complies with frequency allocation in
Europe

1G - Network Access Technique
• Frequency Division Multiple Access
(
(FDMA) )
• Subdivides the available spectrum into a
number of frequency slots
• Each user is assigned a separate frequency.

1G - Services
• Standard voice
• No data services
• No supplementary services
• Call barring

The 1G Landscape
• A series of incompatible networks
• Limited capacity for expansion
• Limited support for roaming
• Susceptible to interference
S ibl i f
• Poor security
• No support for wireless data
• No third party applications

Solution: 2G
• Digital techniques rather than analogue
• Increased flexibility
– error control
tl
– compression
• More efficient use of available bandwidth
• Increased compatibility with the fixed
p y
component of the PSTN
• Increased quality of service
• Possibility of wireless data services

2G - GSM
• Global System for Mobile Communication
(
(GSM))
– Europe and Asia
• Conceived in 1982
• Deployed in 1992 in Europe
• European Telecommunications Standards
l ii dd
Institute (ETSI)
• Most successful 2G system
– 863 million users in 197 countries

2G - D-AMPS
• Digital Advanced Mobile Phone Service
(DAMPS)
– North America
– Also called IS-54 (Interim Standard 54)
• 1991
• Dual mode terminals ensuring backward
compatibility
• IS-136 introduced in 1996
• Telecommunications Industry Association
(TIA) TR-45 Committee

2G - IS-95
• Interim Standard 95 (IS-95)
– North America
• Also called cdmaOne
• 1993
993
• USA
• Qualcomm IncInc.
• Pioneered the use of the network access
technique CDMA

2G - PDC
• Personal Digital Cellular (PDC)
• 1991
• Japan
• Two
T modes d
– Full-rate
– Half-rate
• 12% of global digital subscriptions in 1999.

2G - Network Access Technique
• Time Division Multiple Access (TDMA)
– Users share a frequency band by multiplexing their
transmissions in time
• In practice ..
– A il bl spectrum is divided into frequency
Available t i di id d i t f
channels (recall FDMA!)
– Each frequency channel is further subdivided into
cyclic timeslots (1,2,3,1,2,3,1,2,3 …)
– A call is assigned a time slot

2G - Services
• Depends on
– Network standard
– Operator policies
• Improved standard telephony (speech)
• Basic wireless data
• Additional services
– Call barring

Example: GSM Services
• Teleservices
• Speech
p
• Emergency calls
• Short Message Service (SMS)
• Bearer Services
• Telefax
• Basic data (9.6kb/s)
• Supplementary Services
• Call forwarding
• Call barring

2.5G - GPRS (GSM)
• General Packet Radio Service (GPRS)
• Introduces packet switching to GSM
• “Always-on”
“Al ”
• Uses multiple timeslots (channels)
– 14.4 kb/s per channel
– Maximum of 115.2 kb/s
• Dynamic resource allocation
• Supports IP
• Billing per KB, NOT per sec.

2.5G - EDGE (GSM)
• Enhanced Data rates for GSM Evolution
(
(EDGE) )
• Maximum 384 kb/s
• 8 Phase Shift Keying (8PSK)
– Send more bits down the line
– 3 f ld increase over GSM
fold i
• Two classes of handset:
– Class A (EDGE only on downlink)
– Class B ( EDGE on uplink and downlink)

2.5G - D-AMPS (IS-136+)
• Two phase migration path
– IS-136+
• Integrate GPRS
• Note: packet switching already supported
by Cellular Digital Packet Data (CDPD)!
– IS-136 Hi h S d Outdoor
IS 136 High Speed O td
• Integrate EDGE
• Subscribers can roam between IS-
136HS and GSM networks supporting
EDGE

2.5G - IS-95B (IS-95)
• Enhanced version of IS-95
• Already supports packet switching (CDPD)
• Maximum of 115.2 (8 channels @ 14.4kb/s)
• Realistically
R li i ll …
– 28.8 kb/s to 57.6 kb/s on downlink
– 14.4 kb/s on uplink

2.5G - Services
• Standard services that can use packet
switching:
g
– WWW browsing
– email
– file downloading e.g. mp3
– Multimedia Messaging Service (MMS)

3G - The IMT2000 Initiative
• Conceived in 1986
• Sought to define a single world-wide
world wide
standard for accessing the global
telecommunications infrastructure from
both terrestrial and satellite mobile systems
• Problem: backward compatibility
• So five standards approved for the air
interface!
i f!

3G - Air Interface Standards I
– IMT DS
IMT-DS (Direct Spread), also known as
Wideband CDMA Frequency Division
Duplex (W-CDMA-FDD).
– IMT-TC (Time Code) or W-CDMA Time
Division Duplex (W-CDMA-TDD).
– IMT-MC (Multi-Carrier) or CDMA2000.
– IMT-SC (Single Carrier), also known as
EDGE or UWC-136.
– IMT-FT (Frequency Time), for cordless sytems e.g.
DECT

3G - Network Access Technique
• Code Division Multiple Access (CDMA)
– Signal is modulated with high bandwidth
spreading waveforms called signature waveforms
or codes. Subscribers may submit at the same
frequency and time but signal separation is
q y g p
facilitated via the signature waveform
• In contrast with TDMA
– More robust
– Less susceptible to fading & interference
p g

3G Networks
2 G N e tw o rk 3 G S u c c e sso r
GSM UM TS
PDC C D M A 2000
IS -9 5 C D M A 2000
DAM PS IS -1 3 6 H S o r U M T S

Example: 3G Services (UMTS)
• Universal Mobile Telephone System
(
(UMTS) )
– Four QoS classes of services
• Conversational Class
– Voice, video telephony,video gaming
• Streaming Class
– multimedia, video on demand, webcast
l i di id d d b
• Interactive Class
– WWW browsing, database access, online g
g, , gaming
g
• Background Class
– email, SMS, file downloading

Towards 4G

Wireless System Landscape
Mobility,
Functions
High Mobility
Hi h M bilit
speech, some
data
1G 2G
Limited Mobility:
3G 4G
Speech, data
Fixed Access,
High speed data
WLAN / PAN
In-Home /
In-Building
1Kbps 10Kbps 100Kbps 1Mbps 10Mbps 100Mbps
Data Rate to the User

Image of Wireless Home Network in 4G
TV
antennas
Roaming
Ｐ
with public
Ｃ
PSTN,
networks
ADSL,
ADSL
Mobile
and
terminals
CATV Home Server
Car in
TV
garage
Audio
PDA

Image of Wireless Coffee Shop Hot Spot
Coffee Shop
PDA

Small public cells after 4G
Public cells before 4G due to high carrier frequency
and high data rate.
rate

4G network distribution
Railway
station
Public cell
Private cell

4G and 3G networks
3G cell 4G cell