Wireless Communication Engineering
UNIT 1 PART 2
Wireless Billions of wireless devices are in use 4 wireless technologies in 10
communication technologies with most market potential: Wi-Fi UWB Software Radio Wireless Mesh Other six are: Nanotech, PON, Soft Switching,
MPLS, FSO, Optical Switching
EM Spectrum for Telecom Most spectra licensed; 3G license is very
expensive; FCC is a mighty sector Infrared, ISM band, and amateur radio
band are license-free HW2: Find out what spectrum is used for
GSM, IS-95, 802.11b WLAN. What data rates are available in each system? What transmission characteristics makes these spectrum bands suitable for wireless communications?
APPLICATIONS 1G – analog signals only ( ph call) 2G – sms 2.5G – mms, www ,email access (WAP) 2.75 – High data rate 3G – mobile internet, mobile tv, video
calling 3.5G – mobile broad bands, smart ph,
mobile modems 4G – IP telephony, ultra broadband modems
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. (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. (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
What are the killer applications of 3G? 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
AMPS
VoiceServiceTrack
CDMAIS-95
CDMA2000
4G
ETACS GSM
WCDMA
1st GenerationAnalog
2nd GenerationDigital
3rd GenerationWideband
FixedComputerNetwork
WLAN
PDMA
NorthAmerica
Europe
DataServiceTrack
Voice & DataServiceTrack
4th GenerationWideband All-IP
Notes:IP: Internet ProtocolTCP: Transmission Control ProtocolAMPS: Advanced Mobile Phone ServicesETACS: European Total Access Communication SystemPDMA: Packet Division Multiple Access (Hanwang, China)
Circuit Switching
Packet Switching
Circuit and Packet Switchingevolving to Packet Switching
TD-SCDMAChina
Paradigm From 1G to Beyond 3G
First Generation
• Analogue• Circuit switched• Basic voice
telephony• Low capacity• Limited local
and regional coverage
Second Generation
• Digital• Circuit switched• Voice plus basic
data applications• Low data speed• Enhancements
towards• packet switching• higher data rates
• Trans-national and global roaming
• Digital• Packet and circuit
switched• Advanced data
(multimedia) applications
• Fast data access• Global coverage• Global roaming
Third GenerationBeyond Third
Generation
• Digital• Packet switched• All IP based (IPv6)• More advanced
multimedia applications
• User in control• Flexible platform
of complementary access systems
• High speed data• Improved QoS• Global coverage• Global roaming
Mobility and Information Speed of Evolving Mobile Communication Systems
4G
High_speed
High_capacity
Low bit cost
3G
2G IMT-2000
Mob
ility
High Speed/Nationwide
Moderate Speed/Citywide
Walking/Premises
Static/Indoor
(2001)
(2007-2010?)
0.1 1 10 100
Infomation Speed(Mbit/s)
(2002)
wireless accessMillimeter_wave
LAN
Trends in Wireless Commun.• 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
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
Internet
PSTNISDN
IP/ATM/MPLS Backbone
Mobile Internet Application Platforms
Mobile InternetApplication Servers
Media Gateway
Mobility, Connection& Control Servers
Mobility Gateway Intelligent Edge
Broadband Gateway
IP MultiRadio
OWLAN
Broadband Accesses
Network Domain
Service Domain
Combination of different wireless access systems
IEEE.802.11 WLAN
WPAN WLAN WWAN
PAN Bluetooth
PDMA
Network of 3G beyondServices andapplications
IP based core network
IMT-2000UMTS
WLANtype
cellularGSM
short rangeconnectivit
y
WirelinexDSL
otherentities
DABDVB
return channel:e.g. GSM
download channel
New radiointerface
Transmission Data Rate Highest data rate(3G)
at least 144 Kb/s in a vehicular environment, 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
2G 3G and beyond
9.6-14.4 kbps
evolved 2G
64-144 kbps 384 kbps-2 Mbps 100 Mbps?384 kbps-20 Mbps
System Capacity and spectrum efficiency
Capacity: 5-10 times higher than 3G
Frequency efficiency: Multi-cell: > 2bits/Hz
Single-cell: 5~10 bits/Hz
Drivers of 3G Beyond
3G evolution …but difficult
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 Low system capacity Low spectrum efficiency
0
25
1998 1999 2000 2001
50
75
100
125
150Pbit/day
Real Time(e.g. Voice)
Non Real Time(e.g. Internet access)
MobileInternetUser
MobileUser
0200400600800
10001200140016001800
1995 2000 2005 2010
Subscriptions (millions)MobileFixedMobile InternetFixed Internet
Drivers of 3G Beyond
3G2G
Revolution from subscriber service expectations
Evolution from 2G systems
IP
Revolution from IP infrastructure
and Beyond
0
5
10
15
20
25
1999(Forecast by ITU-R TG-8/1 for Asia)
2015(Extrapolation)
Up Down Up Down Up Down
63%
23?
5.4
1
19.8
10 %
30%
15%
28%
8%3.4
0.50.5
91 %
Multimedia (U:128k,D:10Mbps) (U:128k, D:2Mbps) (U:64k,D:384kbps) (U/D:128kbps×n)
1G/2G servicesVoice (U/D: 16k, VOX0.5)Others (<64 kbps)
9 %
Multimedia traffic increases 40%/year. 10Mbps downstream service emerges. Saturation of 1G/2G services traffic.
Subscribers ×1.5
Voice : Multimedia traffic ratio 1 : 2 (in 2010)
3.9
1.5
Rel
ativ
e tr
affi
c va
lue
in b
its
(Ref
: 19
99)
Year2010
Service Forecast for Asia Region
Multimedia Services
Internet accessShopping/banking(e-commerce)Video conferencingVideo on demandTelemedicineDistance learning
Challenges Unreliable Channels (Cross Layer Design) Scarce Spectrum and Resource
Management Stringent Power Budget Security Location and Routing Interfacing with Wired Networks Health Concern Diversified Standards and Political Struggle