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
