Transcript Wireless Communications and Networks

Evolution of Wireless Communication
By
Chandra Thapa
Evolution of Wireless Systems
Guglielmo Marconi invented the wireless telegraph in
1896
 Communication by encoding alphanumeric characters in
analog signal
 Sent telegraphic signals across the Atlantic Ocean
First public mobile (car-based) telephone system
(MTS) introduced in 1946
 Analog frequency modulation
 High power BS tower to cover 50 miles radius
 Inefficient (120K spectrum for a voice connection)
Evolution of Wireless Sys. (Contd)
Improved mobile telephone system (IMTS) developed
in 1960
Full duplex services and direct-dialing
23 FM channels with BW reduced to 25-30 KHz
Cellular concept
Exploits the attenuation of radio signal with
distance to achieve frequency reuse.
originally proposed by D. H. Ring in 1947
Bell Labs began work on cellular telephone system
in the late 1960s.
Evolution of Wireless Sys. (2.5G)
2G telephony is highly successful
Enhancement to 2G on data service
 GSM: HSCSD and GPRS
 IS-95: IS-95b
 IS-136: D-AMPS+ and CDPD
The improved data rate is still too low to support
multimedia traffic
ITU initiated 3G standardization effort in 1992, and
the outcome is IMT-2000.
Evolution of Wireless Sys. (1G)
Handoff was not solved until the development of
microprocessor, efficient remote-controlled RF
synthesizer, and switching center.
1G Cellular System
 Designed in 1970s, deployed in early 1980s
 Analog, 42 control channels, 790 voice channels
 Handoff performed at BS based on received power
 AMPS in US; TACS in part of Europe; NTT in Japan; C450 in
West German, and NMT in some countries.
 Became highly popular; AMPS still popular in US!
Evolution of Wireless Sys. (2G)
2G Systems
 Digital cellular telephony
 Modest data support, incompatible
 GSM: a common TDMA technology for Europe; claim
about 3/4 of subscribers worldwide.
 IS-54 and IS-136: TDMA technology in US; compatible
with AMPS;
 IS-95: CDMA; standardized in 1993; South Korea and
Hong Kong deployed it in 1995; US in 1996.
Evolution of Wireless Sys. (3G)
IMT-2000 comprises several 3G standards:
EDGE, data rate up to 473Kbps, backward compatible
with GSM/IS-136
cdma2000 (Qualcomm), data rate up to 2Mbps, backward
compatible with IS-95
WCDMA (Europe), introduces a new 5MHz channel
structure; data rate up to 2Mbps;
TD-SCDMA (China), CDMA in TDD fashion
Evolution of Wireless Sys. (4G)
Problems of 3G systems
Immature 3G license auction increases the financial
burden
Difficult to extend to higher data rates
No unified standard (political factors dominate)
4G systems
Research initiated, but still not well-defined
Data-oriented, seamless integrated with wireline
Indoor data rate up to 100 Mbps, outdoor data rate
up to 20Mbps.
Evolution of Mobile Radio Communications
Voice
Service
Track
1st Generation
Analog
2nd Generation
Digital
North
America
AMPS
CDMA
IS-95
Europe
ETACS
GSM
3rd Generation
Wideband
4th Generation
Wideband All-IP
Notes:
IP: Internet Protocol
TCP: Transmission Control Protocol
AMPS: Advanced Mobile Phone Services
ETACS: European Total Access Communication System
PDMA: Packet Division Multiple Access (Hanwang, China)
Circuit Switching
Voice & Data
Service
Track
CDMA
2000
PDMA
Circuit and Packet Switching
evolving to Packet Switching
WCDMA
China
Data
Service
Track
Fixed
Computer
Network
Packet Switching
TDSCDMA
WLAN
4G
Trends in Wireless Comm.
 Personal Communications (Goal of mobile communications)
 All IP based (IPv6) (Packet switched)
 Flexible platform of complementary access systems(
Combination of different wireless access systems, Hot spot
services will be introduced by high-speed wireless access
(>100mbps))
 Higher system capacity (Users/Service, 5-10 times higher than
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


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
3G)
Higher Transmission Data rate
Higher frequency efficiency
More advanced multimedia applications
Improved QoS
Realize high levels of security and authentication
Global coverage
Global roaming
All IP Based
All IP based
Network Domain
Broadband Accesses
Mobility, Connection
& Control Servers
OWLAN
Mobile Internet
Application Servers
Mobile Internet
Application
Platforms
Broadband
Gateway
Service Domain
Internet
IP Multi
Radio
Mobility
Gateway
IP/ATM/MPLS Backbone
Intelligent Edge
Media
Gateway
PSTN
ISDN
Combination of different wireless access
systems
PAN
Bluetooth
PDMA
IEEE.802.11
WLAN
WPAN
WLAN
WWAN
Network of 3G beyond
Services and
applications
New radio
interface
download channel
Wireline
xDSL
DAB
DVB
IP based core network
return channel:
e.g. GSM
cellular
GSM
IMT-2000
UMTS
WLAN
type
other
entities
short range
connectivit
y
Transmission Data Rate
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Highest data rate(3G)
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at least 144 Kb/s in a vehicular environment,
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384 Kb/s in a pedestrian environment,

2048 Kb/s in an indoor office environment.
Highest data rate (4G)
 2Mbps in a vehicular environment, 20Mbps in a pedestrian
environment
 Wide Area, high velocity：100Mbps

Indoor, lower velocity：1Gbps
Evolution of transmission data rate
Drivers of 3G Beyond
3G evolution :
Difficult
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to extend to higher data rate
with CDMA only technology;
to provide various services
with different QoS
to have enough frequency
resource to accommodate
more subscribers
Drawback
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Low system capacity
Low spectrum efficiency
1800 Subscriptions (millions)
1600
1400
Mobile
User
Mobile
Fixed
Mobile Internet
Fixed Internet
1200
1000
Mobile
Internet
User
800
600
400
200
0
1995
2000
2005
2010
Drivers of 3G Beyond
Revolution from IP
infrastructure
IP
2G
Evolution from 2G
systems
3G
and Beyond
Revolution from subscriber
service expectations
Multimedia Services
Internet access
Shopping/banking(e-commerce)
Video conferencing
Video on demand
Telemedicine
Distance learning
Challenges
Unreliable Channels
Scarce Spectrum and Resource Management
Stringent Power Budget
Security
Location and Routing
Interfacing with Wired Networks
Health Concern
Diversified Standards and Political Struggle