this is the begning of the cource mobile and wirless system




LectureOutline Lecture Outline
TheWirelessVision The Wireless Vision
Technical Challenges
h il ? Why Wireless ? 
Types of Wireless Communications
Current Wireless Systems
SpectrumRegulation&Standards Spectrum Regulation & Standards
Main Point
WirelessVision Wireless Vision
Multimedia Wireless Communications Any Time and Anywhere
Applications:
Wireless Information Devices
Wireless LANs
WirelessVideo/M sic Wireless Video/Music
Multimedia Home Networks
Smart Homes/Appliances
Remote Learning/Medicine
Sensorand AdHoc Networks Sensor and Ad-Hoc Networks
Autonomous Vehicles/Robots

TechnicalChallenges Technical Challenges
 Hardware
Multimode operation
Multilayer Design
Multimode operation
Small, lightweight, low power
High‐frequency components
 Communication Link Design
 b ll ffi i ii hi Fast, robust, spectrally efficient communication techniques
Mitigation of wireless channel impairments
 Multiple Access and Resource Allocation
Efficientschemesthatmaximizesystemcapacity Efficient schemes that maximize system capacity
Dynamic resource allocation and efficient spectral reuse
 Networking.
Routing and mobility management for mobile users out gad ob ty aage eto ob euse s
Network reliability, flexibility, and scalability
Deliver QoS to applications/application adaptation
Performance gap with wireline system

Multimediarequirements Multimedia requirements 
Voice Data Video
Delay  < 100 ms ‐ < 100 ms 
Packet loss < 1% < 1%
BER 10
–3
10
–6
10
–6
BER 10 10 10
Data rate  8‐32 Kbps 1‐100 Mbps 1‐20 Mbps
Traffic  Continuous Bursty Continuous 

Wireless(Why?) Wireless (Why?) 
Freedomofwires Freedom of wires
No cost of installing wires or rewiring 
No bunches of wires running here and there g
“auto‐magical” instantaneous communication 
without physical connection setup, e.g.,  
Bluetooth, Wi‐Fi
Global coverage
Communication can reach where wiring is not 
feasible or costly, e.g., rural areas, old buildings, 
battlefieldsvehicles outerspaceetc

Wireless(Why?) Wireless (Why?)
Stayconnected Stay connected
Roaming allows to stay connected anywhere 
anytime
rapidly growing market attests to public need for 
mobilityandun‐interuppted access mobility and uninteruppted access  
Feasibility
Servicesreachyouwhereyougo(Mobility) Services reach you where you go  (Mobility) 
Connect to multiple devices simultaneously (no 
physicalconnectionrequired)

WirelessvsMobile Wireless vsMobile 
Wirelessdonotnecessarilymeanmobile Wireless do not necessarily mean mobile 
il b Wireless systems may be 
Fixed (e.g., metropolitan networks)
Portable (e.g., interaction between TV and VCR)
Mobile (e.g., mobile phones) 

TypesofWirelessCommunication Types of Wireless Communication
Mobile 
Cellular phones (GSM/cdma2000) 
Portable Portable 
IEEE 802.11
Fixed 
IEEE 802.16 (Wireless MAN) –first tested in south 
korea! 

Types of Wireless communication 

 Radio Transmission 
Easily generated, travel long distance, easily penetrate 
buildings. 
Problems: 
•Frequency dependent 
•Relatively low bandwidth for data communication 
•Strict spectrum regulations 
 Microwave Transmission 
Widely used for long distance communications 
GivesahighS/Nratio relativelyinexpensive Gives a high S/N ratio, relatively inexpensive 
Problems:
•Do not pass through buildings (Shadowing) 
•Weatherandfrequencydependent


Types of Wireless communication 
Infrared and millimeter wave
Widely used for short range communications 
Unable to pass through solid objects 
Udf id il LAN tf td Used for indoor wireless LANs, not for outdoors 
Light‐wave transmission  
UnguidedopticalsignalsuchasLaser Unguided optical signal such as Laser
Connect two LANs via optical communications 
Unidirectional, easy to install, do not require license
Problems: 
•Unable to pass through rain or thick fog
•Laser beam can easily be diverted by turbulent air 


 Current Wireless Systems
 Point‐to‐PointWirelessLinks PointtoPoint Wireless Links
 Cellular Systems
 Wi l LAN  Wireless LANs
 Wireless WANs
 Ad‐Hoc Wireless Networks
 Satellite Systems
 HomeRF and Bluetooth

CellularSystem Cellular System
 A large  geographical region  g ggp g
is segmented into smaller 
“cells”. 
Transmitpowerlimitation Transmit power limitation 
Facilitates frequency spectrum 
re‐use
 Cellular network design 
issues 
Inter‐cell synchronization 
Handoff mechanism 
Frequencyplanning

CellularWirelessSystem Cellular Wireless System
Frequencyreuse Frequency reuse 
Frequency re‐use = 1
‐Higher spectral efficiency 
Frequency re‐use = 7
‐lower interference for cell‐edge users  
 Cellular Wireless System 
Frequencyreuse=3 Frequency reuse = 3 

CellularWirelessEvolution Cellular Wireless Evolution
4G
System beyond IMT‐2000 (IMT‐Advanced)
LTE/LTE‐Advanced, WiMax (802.16m)
3G
IMT 2000 Global standard | Wideband CDMA (‘00s)
UMTS/WCDMA/HSPA, CDMA2000, TD‐CDMA
2G
Digital modulation & roaming | TDMA & CDMA (‘90s)
GSM, IS‐95, PDC
1G Analog speech | FDMA (‘80s)
AMPS

Wireless Local Area Networks 
WLANconnectlocal computers WLAN connect local computers
100 m range, confined places 
Breaksdatainto packets Breaks data into packets
Channel access is shared (random access) 
 backbone internet provide best effort service
Problems:
Poor performance in some cases (e.g., video)
Limitedmobility

Satellite Systems
Coversverylarge areas Covers very large areas
Very useful in sparsely populated areas: rural 
areasseas mountains areas, seas, mountains  
 Different orbit heights
GEOs(39000km) LEOs(20000km) GEOs (39000 km), LEOs (20000 km) 
Optimized for one way transmission
Expensive base stations (satellite
Limitedquality/voicetransmission Limited quality/voice transmission 
Typical applications 
Weathersatellites Weather satellites
TV and radio satellites
Militarysatellites Military satellites
Telecommunication applications 
Globaltelephoneconnections Global telephone connections 
Backbone for Global Network
GPS

 Paging Systems 
Broadcoverageforshortmessages Broad coverage for short messages
Message broadcast from all BSs
Si l il Simple terminals
Low cost, low complexity, very low power devices 
Optimized for one way transmission
Call back, very hard , y
Replaced by Cellular! 

 Personal Area Networks 

 Bluetooth 
Cable replacement RF technology
Short range (10m, extendable to 100m)
Operate at around 2.45 GHz (2.40 to 2.45 GHz) crowded!  p
Divided into 79 channels
1 data (700 kbps) and three voice channels
1 Mbps data rate shared between 7 devices p
TDD duplex schemes 
Polling based multiple access
Widelysupported Widely supported 
FHSS is used to minimize interference & fading 
The modulation technique is Gaussian frequency‐shift keying
Themaximumtransmittedpoweris0dBm(1mW)

merging Wireless Networks 

AdhocWirelessNetworks Ad hoc Wireless Networks
Sensor Networks
iib dClS Distributed Control Systems
Ultra Wide Band (UWB) Systems 
 Ad‐Hoc Networks
 Peertopeercommunications Peer to peer communications 
 No backbone infrastructure
 Routing can be multi‐hop
 Topology is dynamic 
 Fully connected with different SINRs

 Sensor Networks 

Nodes powered by self rechargable batteries
Data flows to centralized locations 
Low per node rates but upto 1000 nodes
D hi hl ldi i d Data highly correlated in time and space
Nodes can cooperate in transmission, reception,  
compression andsignalprocessing

 Ultra Wide Band (UWB) Systems 
UltraWideBand(UWB)Systemsisan Ultra Wide Band (UWB) Systems is an 
emerging wireless technology that can 
transmitdataataround100Mbps(upto1000 transmit data at around 100 Mbps (upto1000 
Mbps) 
UWBtransmitsultralow powerradiosignals UWB transmits ultra low power radio signals 
with very narrow pulses (nanosecond) 
B fi l i i i Because of its low power requirements, it is 
very difficult to detect (hence secure)  

SpectrumRegulation Spectrum Regulation
 Spectral Allocation in US controlled by FCC  p y
(commercial) or OSM (defense)
 FCCauctionsspectralblocksforsetapplications FCC auctions spectral blocks for set applications.
 Some spectrum set aside for universal use
 Worldwide spectrum controlled by ITU‐R

Standards
 Interacting systems require standardization
 Companies want their systems adopted as standard
Alternativelytryforde‐factostandards Alternatively try for defacto standards
 Standards determined by TIA/CTIA in US
IEEE tddft dtd IEEE standards often adopted
 Worldwide standards determined by ITU‐T
In Europe, ETSI is equivalent of IEEE for standards 
development.
Main Points
 The wireless vision encompasses many exciting systems 
d li ti ltf titi and applications –plenty of opportunities
 Technical challenges transcend across all layers of the 
systemdesign–optionsforfurtherresearch system design –options for further research
 Wireless systems today have limited performance and 
interoperability –thatmotivatesustoworkon interoperability  that motivates us to work on 
improving system performance: further research
 Standardsandspectralallocationheavilyimpact the Standards and spectral allocation heavily impact the 
evolution of wireless technology –Integration of various 
types of wireless systems