2001/11/30 Prof. Huei-Wen Ferng 1 Chapter 5 Introduction to Personal Communications Systems (PCS):...
-
Upload
kathleen-norris -
Category
Documents
-
view
217 -
download
1
Transcript of 2001/11/30 Prof. Huei-Wen Ferng 1 Chapter 5 Introduction to Personal Communications Systems (PCS):...
2001/11/30 Prof. Huei-Wen Ferng 1
Chapter 5Chapter 5
Introduction to Personal Introduction to Personal Communications Systems (PCS):Communications Systems (PCS):
What’s PCS and its PrinciplesWhat’s PCS and its Principles
2001/11/30 Prof. Huei-Wen Ferng 2
What’s PCSWhat’s PCS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 33
What is Personal What is Personal Communication?Communication?
A PCS provides people with wireless A PCS provides people with wireless access to information serviceaccess to information service• e.g. Cordless, cellular, mobile data e.g. Cordless, cellular, mobile data
networks and etc.networks and etc. Mobility is the heart of PCSMobility is the heart of PCS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 44
Characteristics of PCSCharacteristics of PCS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 55
Characteristics of PCSCharacteristics of PCS Personal Information Machine (PIM)Personal Information Machine (PIM)
• Information device carried by the person Information device carried by the person such as PDA, Notebook, Cellular Phonesuch as PDA, Notebook, Cellular Phone
Personal AddressPersonal Address• Associated with the person as he or she Associated with the person as he or she
changes locationchanges location Personal ProfilePersonal Profile
• Contains details of services selected by the Contains details of services selected by the subscribersubscriber
Ubiquitous: Ubiquitous: • Services will be available anywhere & Services will be available anywhere &
anytimeanytime
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 66
Dimensions of PCSDimensions of PCS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 77
Examples of Two Telephone CallsExamples of Two Telephone Calls
Conventional CallConventional Call• A pair of wires connects each telephone A pair of wires connects each telephone
to the switching systemto the switching system• Each pair of wires has its own Each pair of wires has its own
telephone numbertelephone number Cellular CallCellular Call
• Wireless: Signals travel through the airWireless: Signals travel through the air• Each host associates with a telephone Each host associates with a telephone
number regardless of locationnumber regardless of location
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 88
Conventional Phone Call:Conventional Phone Call:Network ElementsNetwork Elements
Public SwitchedTelephone Network
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 99
Conventional Phone Call: Conventional Phone Call: Information FlowInformation Flow
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1010
Cellular Phone Call:Cellular Phone Call:InitializationInitialization
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1111
Cellular Phone Call: Cellular Phone Call: Service RequestService Request
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1212
Cellular Phone Call: Cellular Phone Call: PagingPaging
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1313
Cellular Phone Call:Cellular Phone Call: Response to PagingResponse to Paging
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1414
Cellular Phone Call:Cellular Phone Call: Channel AssignmentChannel Assignment
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1515
Cellular Phone Call:Cellular Phone Call: ConversationConversation
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1616
Cellular Phone Call:Cellular Phone Call: Handoff (Hard and Soft)Handoff (Hard and Soft)
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1717
A Cellular SystemA Cellular System
A cellular system includes:A cellular system includes:• Telephone sets, radio channels, base Telephone sets, radio channels, base
stations, a switch, and connections stations, a switch, and connections linking to the switchlinking to the switch
Cellular systems are more complex Cellular systems are more complex than conventional telephone systemsthan conventional telephone systems
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1818
Network ElementsNetwork Elements
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 1919
Information FlowInformation Flow
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2020
Technical ChallengesTechnical Challenges
MobilityMobility: Roaming: Roaming• Location management and HandoffLocation management and Handoff
EtherEther: Radio signals: Radio signals• Access technologyAccess technology: FDMA, TDMA, CDMA: FDMA, TDMA, CDMA• Channel impairmentsChannel impairments: fading and noise: fading and noise• BandwidthBandwidth: channel reuse, signal compression, : channel reuse, signal compression,
an efficient modulation and codingan efficient modulation and coding• Privacy and SecurityPrivacy and Security: Encryption and : Encryption and
AuthenticationAuthentication EnergyEnergy: Power control: Power control
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2121
Evolution of PCSEvolution of PCS
Four stepping-stones to PCSFour stepping-stones to PCS• Cellular NetworksCellular Networks• Cordless TelephonesCordless Telephones• Mobile ComputingMobile Computing• PagingPaging
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2222
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2323
Cellular NetworksCellular Networks
Four major trends in cellular Four major trends in cellular technologies:technologies:• Analog systems Analog systems Digital systemsDigital systems• Signaling and network control Signaling and network control
technologies technologies StandardStandard• Vehicle-mounted Vehicle-mounted Small portable unitsSmall portable units• Expanding the scope of services such as Expanding the scope of services such as
caller ID, transmit text message, direct caller ID, transmit text message, direct access to internet and WWWaccess to internet and WWW
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2424
StandardsStandards
AMPSAMPS (Advanced Mobile Phone System) (Advanced Mobile Phone System) • Used in the US and CanadaUsed in the US and Canada• Frequency bands: 850 MHzFrequency bands: 850 MHz• Access: FDMAAccess: FDMA• More than 700 service areas (two More than 700 service areas (two
companies/each area)companies/each area) GSMGSM (Global System for Mobile (Global System for Mobile
Communications)Communications)• Used in EuropeUsed in Europe• Frequency bands: 900 MHz &1800 MHzFrequency bands: 900 MHz &1800 MHz• Access: TDMAAccess: TDMA
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2525
GSM and its PredecessorGSM and its Predecessor
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2626
AMPS and its SuccessorAMPS and its Successor
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2727
Cordless PhonesCordless Phones
Limited distance from a single residential Limited distance from a single residential BSBS
Standards: CT2 (Cordless Telephone, Standards: CT2 (Cordless Telephone, Second Generation), DECT (Digital Second Generation), DECT (Digital European Cordless Telecommunications) European Cordless Telecommunications) and CT2Plusand CT2Plus• To interconnect many different base stations To interconnect many different base stations
such as residential BSs, BSs connected to such as residential BSs, BSs connected to business telephone systems (PBX), and business telephone systems (PBX), and telepoint BSs (BS in public area)telepoint BSs (BS in public area)
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2828
Mobile Computing and PagingMobile Computing and Paging
Mobile Computing = Portable Mobile Computing = Portable Computers + InternetComputers + Internet
Paging is the oldest of PCS and the Paging is the oldest of PCS and the cheapest onecheapest one
The most advanced pagers also The most advanced pagers also receive voice email receive voice email
Two-way paging services are Two-way paging services are supported since 1995 in USAsupported since 1995 in USA
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 2929
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3030
Current PCSCurrent PCS EuropeEurope: The term of PCS originated in 1989 in t: The term of PCS originated in 1989 in t
he United Kingdomhe United Kingdom• Spectrum is assigned around 1800 MHzSpectrum is assigned around 1800 MHz
North AmericaNorth America::• Spectrum is assigned around 1900 MHzSpectrum is assigned around 1900 MHz • High-tier systems: High transmission power serving High-tier systems: High transmission power serving
at vehicle speed such as NA-TDMA, NA-CDMA, GSMat vehicle speed such as NA-TDMA, NA-CDMA, GSM Low-tier systemsLow-tier systems: PACS (Personal Access Com: PACS (Personal Access Com
munications system), DECTmunications system), DECT JapanJapan: A low-tier system PHS (Personal Handy: A low-tier system PHS (Personal Handy
phone System) operated in 1995phone System) operated in 1995
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3131
Frequency BandsFrequency Bands
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3232
Other Wireless Other Wireless Communications SystemsCommunications Systems
Four important systems to serve Four important systems to serve special needsspecial needs• Mobile communication satellitesMobile communication satellites: low-: low-
bit-rate, global coverage areabit-rate, global coverage area• Wireless local area networksWireless local area networks: high-bit-: high-bit-
rate, limited coverage arearate, limited coverage area• Wireless local loopsWireless local loops: higher spectrum : higher spectrum
efficiencyefficiency• Wireless data networksWireless data networks: diversity: diversity
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3333
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3434
Mobile Satellite SystemsMobile Satellite Systems
A major trends since 1990:A major trends since 1990:• Broadcast satellite TV industryBroadcast satellite TV industry• Two-way communication between Two-way communication between
satellites and vehicles, shipssatellites and vehicles, ships• One-way GPSOne-way GPS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3535
Categories of Satellite Categories of Satellite SystemsSystems
GEOGEO (geosynchronous orbits) at 35,800 (geosynchronous orbits) at 35,800 km above the equatorkm above the equator• Advantage: simple network configuration (3 Advantage: simple network configuration (3
satellites are enough to cover the earth)satellites are enough to cover the earth)• Disadvantages: high transmission power, Disadvantages: high transmission power,
long propagation path delay, poor radio long propagation path delay, poor radio coverage at high latitudescoverage at high latitudes
MEOMEO (Medium Earth Orbits) at 10,000 (Medium Earth Orbits) at 10,000 km above the earthkm above the earth
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3636
Categories of Satellite Categories of Satellite SystemsSystems
LEOLEO (Low Earth Orbits) on the order (Low Earth Orbits) on the order of 500 to 2,000 km above the earthof 500 to 2,000 km above the earth
Both the MEO and LEO satellite Both the MEO and LEO satellite systems required handoff in satellitessystems required handoff in satellites
Channel Transmission rates: Channel Transmission rates:
2.4Kbps ~ 2 Mbps2.4Kbps ~ 2 Mbps
2001/11/30 Prof. Huei-Wen Ferng 37
Principles of PCSPrinciples of PCS
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3838
Information Services for PeopleInformation Services for People Telephone ServicesTelephone Services Short Message Services (SMS)Short Message Services (SMS) Voice-band Data and FacsimileVoice-band Data and Facsimile Direct Digital AccessDirect Digital Access
• Transparent data transmission: using FECTransparent data transmission: using FEC• Non-transparent data transmission: using Non-transparent data transmission: using
ARQARQ Closed User GroupsClosed User Groups TelemetryTelemetry Wireless Local LoopsWireless Local Loops Video and Other Broadband ServicesVideo and Other Broadband Services
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 3939
Voice-band Data and FacsimileVoice-band Data and Facsimile
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4040
Figures of Merit (Design Goals)Figures of Merit (Design Goals) Subscribing to a system: Subscribing to a system:
• Terminal price,Terminal size and weight, Terminal price,Terminal size and weight, Service price, Range of services, Coverage Service price, Range of services, Coverage area, Roamingarea, Roaming
Using a system: Using a system: • User interface, Call blocking, Setup time, User interface, Call blocking, Setup time,
Transmission quality, Privacy,Mobility, Call Transmission quality, Privacy,Mobility, Call dropping, Battery life, Modes of operationdropping, Battery life, Modes of operation
Operating company: Operating company: • Infrastructure cost, Cell radius, Spectrum Infrastructure cost, Cell radius, Spectrum
efficiency, Network security, Early deployment efficiency, Network security, Early deployment and adaptabilityand adaptability
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4141
System OperationsSystem Operations
User Information TransportUser Information Transport Mobility ManagementMobility Management Authentication and EncryptionAuthentication and Encryption Call ManagementCall Management Radio Resources ManagementRadio Resources Management OOperations, perations, AAdministration and dministration and
MMaintenance (OA&M)aintenance (OA&M)
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4242
Radio Resources Radio Resources ManagementManagement
Resources assigned by the system to a Resources assigned by the system to a terminal includes:terminal includes:• A base stationA base station• A physical channel depends on the access A physical channel depends on the access
technologytechnology• The power of the signal transmitted by the The power of the signal transmitted by the
terminalterminal• The power of the signal transmitted to the The power of the signal transmitted to the
terminal by the base stationterminal by the base station RRM is an combination optimization problemRRM is an combination optimization problem
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4343
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4444
Four Separate TasksFour Separate Tasks
Call AdmissionCall Admission• Determine whether the system accepts a Determine whether the system accepts a
request to set up a new communicationrequest to set up a new communication Base Station and Channel AssignmentBase Station and Channel Assignment
• Fixed channel allocationFixed channel allocation• Dynamic channel allocationDynamic channel allocation
Power ControlPower Control• Reduce system interferenceReduce system interference• Promote battery lifePromote battery life
Handoff CriteriaHandoff Criteria
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4545
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4646
PCS Architecture: PCS Architecture: Network ElementsNetwork Elements
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4747
Examples: Cellular - CentralizedExamples: Cellular - Centralized
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4848
Cordless - DistributedCordless - Distributed
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 4949
Air InterfacesAir Interfaces
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5050
Obstacles of Radio Obstacles of Radio TransmissionTransmission
Limited spectrum that must be shared Limited spectrum that must be shared efficientlyefficiently
Transmission impairments that can Transmission impairments that can change abruptly with time, location and change abruptly with time, location and frequency bandfrequency band
Interrupted connections associated with Interrupted connections associated with handoff procedureshandoff procedures
Limited power available to portable Limited power available to portable terminalsterminals
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5151
How to Conquer the ObstaclesHow to Conquer the Obstacles
ModulationModulation Source codingSource coding Channel codingChannel coding InterleavingInterleaving Diversity receptionDiversity reception Channel equalizationChannel equalization
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5252
Media AccessMedia Access
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5353
Media AccessMedia Access
Three frequently used access Three frequently used access techniques: techniques: • FDMAFDMA• TDMATDMA• CDMACDMA
Two multiplexing methods:Two multiplexing methods:• TDMTDM• FDMFDM
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5454
Review ExerciseReview Exercise
1.1. Why do cellular phone systems require handoff Why do cellular phone systems require handoff procedures?procedures?
2.2. What are some advantages and disadvantages What are some advantages and disadvantages of using communications satellites to provide of using communications satellites to provide wireless personal communications?wireless personal communications?
3.3. Why does a terminal register its location with a Why does a terminal register its location with a network? What is the advantage of frequent network? What is the advantage of frequent registration? What is the disadvantage?registration? What is the disadvantage?
4.4. Compare fixed channel allocation with dynamic Compare fixed channel allocation with dynamic channel allocation. What are some advantages channel allocation. What are some advantages and disadvantages of the two approaches? and disadvantages of the two approaches?
2001/11/302001/11/30 Prof. Huei-Wen FerngProf. Huei-Wen Ferng 5555
ReferencesReferences
David J. Goodman, Wireless Personal David J. Goodman, Wireless Personal Communications Systems, Chapter Communications Systems, Chapter One and Two.One and Two.