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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
CSIE51800: Advanced Database Systems
Mobile and Pervasive Computing
Wireless Networking
Essentials
Shiow-yang Wu
Department of Computer Science
and Information Engineering
National Dong Hwa University
First-Generation (1G)
Year Event and Characteristics
1970s Development of radio and computer technologies for
800/900-MHz mobile communication
1976 WARC(World Administrative Radio Conference)
allocates spectrum for cellular radio
1979 NTT(Nippon Telephone & Telegraph) introduces the
first cellular system in Japan
1981 NMT(Nordic Mobile Telephone) 900 system introduced
by Ericsson Radio System AB and deployed in
Scandinavia
1984 AMPS(Advanced Mobile Phone Service) introduced by
AT&T in North America
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Second-Generation (2G)
Year Event and Characteristics
1982 CEPT(Conference European des Post of
Telecommunications) establishes GSM(Global Special
Mobile) to define future Pan-European cellular radio
standards
1990 Interim Standard IS-54(USDC: United States Digital
Cellular) adopted by TIA(Telecommunications Industry
Association)
1990 Interim Standard IS-19B(NAMPS: Narrowband AMPS)
adopted by TIA
1991 Japanese PDC(Personal Digital Cellular) system
standardized by the MPT(Ministry of Posts and
Telecommunications)
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Second-Generation (2G)
Year Event and Characteristics
1992 Phase I GSM system is operational
1993 Interim Standard IS-95(CDMA) adopted by TIA
1994 Interim Standard IS-136 adopted by TIA
1995 PCS Licenses issued in North America
1996 Phase II GSM is operational
1997 North American PCS deploys GSM, IS-54, IS-95
1999 IS-54: used in North America; IS-95: used in North
America, Hong Kong, Israel, Japan, South Korea, and
China, etc.; GSM: used in 110 countries
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Existing Wireless Voice
Networks
The U.S. Analog Mobile Phone System (AMPS, 19.2 kbps)
The Global System for Mobile communications (GSM,9.6
kbps)
Digital Cellular mobile phone (such as CDMA, code
division multiple access, higher data rate)
Personal Communications Systems (PCS, paging and
voice mail)
The Digital European Cordless Telecommunications
(DECT, cordless home or PBX telephone)
……
Personal Handyphone System (PHS, Japan)
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GSM
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
General Packet Radio Service
(GPRS, 2.5G)
In order to improve GSM’s data transmission
capacities (Circuit switching, low data rate 9.6
kbps)
GPRS provides packet mode transfer for
applications with a selection of QoS parameters
for service request
It allows for broadcast, multicast and unicast
service and easily working with the packet-
oriented Internet.
Depending the coding, a transfer rate of up to
150 Kbps is possible.
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Third-Generation (3G)
IMT-2000 Fulfill one’s dream of anywhere, anytime
communication
Key Features High degree of commonality of design
worldwide
Compatibility of services within IMT-2000
and with the fixed networks
High quality
Small terminal for worldwide use
Worldwide roaming capability
Capability for multimedia applications and a
wide range of services and terminals
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Third-Generation (3G)
Important 2 Mbps for fixed environment
Components 384 kbps for indoor/outdoor and pedestrian
environment
144 kbps for vehicular environment
Standardization In progress
Work
Service Started in October 2001 in Japan (W-CDMA)
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Why 3G?
GSM (2G), GPRS (2.5G): data rate not high
enough, QoS for applications was clearly not
prioritized in 2.5G, open APIs missing
As new systems emerge, it is crucial to have a
through-through migration strategy. In other
words, 3G system (most of the time) includes 3G,
2.5G and 2G functionalities.
All of the alternative 3G standards will have
seamless hand over capabilities for 2.5G and 2G
from day one – in networks as well as for
handsets.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
What is 3G ?
The ITU has made a recommendation (ITU-R
M687-2) on what the 3G system, or International
Mobile Telecommunications 2000 (IMT 2000),
should bring:
A QoS that is comparable to fixed voice networks.
A phased development, with the first phase supporting
bit rates of up to 2Mbps.
The capability to build diverse terminals from what 2G
phones offer up to what you can carry in vehicles.
A flexible architecture where you can easily add
additional applications.
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3G Standardization
This standardization was driven separately in the
USA, Japan and Europe.
USA: EDGE(Enhanced Data rates for GSM
Evolution) and cdma2000
Japan: WCDMA
Europe: UMTS(Universal Mobile
Telecommunications System )
The ITU called for 10 proposals. The result was
one WCDMA standard, and the Third-Generation
Partnership Project (3GPP) formed.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Key Features of ALL 3G
Systems
Higher bit rates from hundreds of Kbps up to
2Mbps, for channels that are either circuit
switched or packet switched.
When a connection is set up between a user and
the network, an agreement on the QoS comes
into place.
Bit rates dependent on distance and moving
speed. In general, the further away from a base
station, the harder it is to achieve high speeds.
Often consists of different technologies within the
same network
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Subscriber Growth
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Coverage Aspect of 3G
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IMT2000 Global Access
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Transmission Capacity vs
Mobility
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Mobility
An integral factor of mobile systems that has the
most significant effect on system design.
Can be characterized by
Personal mobility
Terminal mobility
Service mobility
“Anytime anywhere” service is the goal.
For some applications, “many time” or “many
where” services may be adequate enough.
(Examples?)
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Technologies 1
Technology: Cellular
Services: Voice and data through handheld
phones
Coverage Area: Continuous coverage limited to
metropolitan regions
Limitations: Available bandwidth is very low for
most data intensive applications
Examples: Cellular phones, PDAs
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Wireless Technologies 2
Technology: Wireless LAN
Services: Traditional LAN extended with wireless
interface
Coverage Area: Used only in local environments
Limitations: Limited range
Examples: NCR’s wavelan, Motorola’s ALTAIR,
Proxim’s range LAN, Telesystem’s ARLAN, IEEE
802.11 …
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Technologies 3
Technology: GPS
Services: Helps to determine the three-
dimensional position, velocity, and time
Coverage Area: Anyplace on the surface of the
earth
Limitations: It is still not affordable by everyone
Examples: GNSS, NAVSTAR, GLONASS
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Wireless Technologies 4
Technology: Satellite-based PCS
Services: Applications mainly for voice paging
and messaging
Coverage Area: Almost anyplace on earth
Limitations: It is costly
Examples: Iridium, Teledesic
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Technologies 5
Technology: Ricochet
Services: High-speed, secure mobile access to
the desk-top (data) from outside the office
Coverage Area: Some major cities, airports,
and some university areas
Limitations: Has a transmission limitations.
Environmental conditions affect quality of service.
Examples: MicroCellular Data Network (MCDN)
Mobile and Pervasive Computing Wireless Networking Essentials 22
Wireless Technologies 6
Technology: Home networking
Services: To connect different PCs in the house
to share files and devices such as printers
Coverage Area: Anywhere in the house
Limitations: Limited to a home
Examples: Netgear Phone line 10X, Intel
AnyPoint Phoneline Home Network, 3Com Home
Connect Home Network Phoneline
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Technologies 7
Technology: Ad hoc networks
Services: Group of people come together for a
short time to share data
Coverage Area: Equal to that of local area
network, but without fixed infrastructure
Limitations: Limited range
Examples: Conference room, defense
applications
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Wireless Technologies 8
Technology: Sensor networks
Services: A large number of tiny sensors with
wireless capabilities
Coverage Area: Relatively small terrain
Limitations: Very limited range
Examples: Defense and civilian applications
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Technologies 9
Technology: Bluetooth
Services: All digital devices can be connected
without any cable
Coverage Area: Private ad-hoc groupings away
from fixed network infrastructures
Limitations: Range is limited due to the short
range radio link used
Examples: Home devices
Mobile and Pervasive Computing Wireless Networking Essentials 26
Characteristics of Wireless
and Mobile Systems
Public Sphere
Traffic information system, personal security, disaster
information systems, etc.
Business Sphere
Mobile videophone, video conference, data email, etc.
Private Sphere
Video-based information services, music on demand,
portable TV, interactive TV, interactive games, video
on demand, electronic newspapers and books,
shopping, home schooling system, information service
for pagers, news, weather forecasts, financial
information, etc.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Medical Application
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Applications of Different
Services 1
Electronic Mail
Field service
Sales force
Transportation industry
Vending
Public safety
Stock trading
Airline activities
Bill paying
Field audit
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Applications of Different
Services 2
WLAN (Wireless LAN)
Retail
Warehouses
Manufacturing
Students
Telediagnostics
Hospitality
General office
Health care
Mobile and Pervasive Computing Wireless Networking Essentials 30
Applications of Different
Services 3
GPS
Surveying
Car rental agency
ROBIN Toll collection
Sports
Satellite-Based PCS
Iridium (銥計畫, 行動通訊衛星)
Teledesic
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Cell
BS: base station
MS: mobile station
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Cellular Network
Mobile and Pervasive Computing Wireless Networking Essentials 33
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Bandwidth Multiplexing
Only a limited amount of bandwidth is allocated
for wireless service.
To increase the effectiveness, multiplexing
techniques are used to improve the overall
performance.
Three basic multiplexing techniques
Frequency Division Multiple Access (FDMA)
Time Division Multiple Access (TDMA)
Code Division Multiple Access (CDMA)
Mobile and Pervasive Computing Wireless Networking Essentials 34
FDMA
The frequency band is divided into a number of
subbands, called channels, and one channel is
allocated by the BS to each user.
FDMA is used in all 1G cellular systems.
1 2 3 4 n
Frequency Frequency
Total bandwidth
User n Frequency 1
User 1
Frequency 2
User 2
User 2
User 1 Frequency n
Time User n
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
TDMA
One channel is used by several users.
BS assigns time slots for different users.
Each user is served in a round-robin method.
1 2 3 4 n
Time
Frame
Frequency
Time 1
User 1
Time 2
User 1
User 2
User n
User 2
Time n
Time User n
Mobile and Pervasive Computing Wireless Networking Essentials 36
CDMA
CDMA utilizes a wider frequency band for each user.
The transmission frequency is distributed over the
wireless spectrum (thus the name spread spectrum).
One unique code is assigned by the BS to each user
and distinct codes are used for different users.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
CDMA Coding and Decoding
The code is employed by a user to mix with each
bit of info before transmission.
The same code (or key) is used to decode.
Any variation is interpreted as noise.
Enable transmission of data from multiple users
simultaneously using the full frequency band.
The number of users is determined by the
number of possible orthogonal codes.
Some 2G and most 3G systems employ CDMA.
Mobile and Pervasive Computing Wireless Networking Essentials 38
CDMA Code
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Frequency Range
Systems BS trans BS receive RF Channel
range/MS range/MS
receive range trans range
FDMA (AMPS) 870~890 825~845 0.03 MHz
MHz MHz
TDMA (GSM 940~956 810~826 0.03 MHz
9000) MHz MHz
CDMA (IS-95) 869~894 824~849 1.25 MHz
MHz MHz
Mobile and Pervasive Computing Wireless Networking Essentials 40
Frequency Hopping
A combination of FDMA and TDMA in terms of frequency
use and time multiplexing.
One user employs one channel for a prespecified time
period and then changes to another channel for
transmission.
The receiver can tune into the transmitter by using the
same frequency hopping sequence.
For multiple users, different sequences can be used as
long as, at any given time, one channel is used by only
one user.
Primarily introduced for defense purpose.
Can also be used to avoid the “jamming” effect.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Frequency Hopping
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Evolution of Cellular Systems
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Cellular System Infrastructure
Mobile and Pervasive Computing Wireless Networking Essentials 44
Cellular System Infrastructure
BS (Base Station) and MS (Mobile Station)
BSC: BS Controller
MSC: Mobile Switching Center
PSTN: Public Switched Telephone Network
backbone
ATM: Asynchronous Transfer Mode
BS = BTS(Base Transceiver System) + BSC
HLR (Home Location Register): located at MSC where the MS
is registered
VLR (Visitor Location Register)
All incoming call will go to the home MSC of the MS first, then
to the MSC where the MS is currently located.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Channels between BS and MS
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Handshakes: BS and MS
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless Communication
Mobile and Pervasive Computing Wireless Networking Essentials 48
Satellite Systems
Have been in use for several decades.
Can cover large areas due to the rotation around
the earth.
Information transmitted should be correctly
received from one of the earth stations (ESs).
Only “line of sight (LOS)” communication is
possible.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Satellite Cell
Why Satellite Component Needed?
Global roaming
Contiguous coverage in areas where terrestrial links are not
feasible (planes, ships, rural areas)
Contiguous coverage in dense areas (fill the gaps)
Disaster proof links
Limitations on a Satellite Component
Propagation delay
Attenuation (衰減 )
Doppler Shift (except geosynchronous orbits)
Light from moving objects will appear to have different
wavelengths depending on the relative motion of the source and
the observer.
Mobile and Pervasive Computing Wireless Networking Essentials 50
Service Characteristics
Large coverage areas
Highly scalable, client installation can be done
immediately without long term planning.
Transmission cost does not vary with distance.
Better tolerance to weather and disaster than ground
systems.
High total capacity. ACTS (Advanced Communication
Technology Satellite) can reach 1Gbps with transmission
rate over 622Mbps. ATM services can reach 45Mbps. 中
新一號衛星(ST-1) provides 1.5Mbps multimedia trans.
Support multicast-oriented system.
Satellite terminal equipment can be installed easily (e.g.,
DirectPC), but the overall cost is still high.
Mobile and Pervasive Computing Wireless Networking Essentials 51
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
History of Satellite Systems
1945 Arthur C. Clarke publishes an essay titled “Extra
Terrestrial Relays” (see ACC in next slide)
1957 First satellite, SPUTNIK
1960 First reflecting communication satellite, ECHO I
1963 First geosynchronous satellite, SYNCOM 2
1964 First geostationary satellite, SYNCOM 3
1965 First commercial geostationary satellite, “Early
Bird” (INTELSAT I): 240 duplex telephone
channels or 1 TV channel, 1.5 years lifetime
1976 Three MARISAT satellites for maritime
communication
1982 First mobile satellite telephone system
INMARSAT-A
Mobile and Pervasive Computing Wireless Networking Essentials 52
Arthur C. Clarke
Mobile and Pervasive Computing Wireless Networking Essentials 53
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
SPUTNIK 1
Mobile and Pervasive Computing Wireless Networking Essentials 54
ECHO I
10-story
building
Mobile and Pervasive Computing Wireless Networking Essentials 55
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
SYNCOM
Diameter:
0.71 m (2 ft 4 in)
Panel Height:
0.39 cm (1 ft 3 in)
Weight in Orbit:
35 kg (78 lb)
Mobile and Pervasive Computing Wireless Networking Essentials 56
History of Satellite Systems
1988 First satellite system for mobile phones and data
communication, INMARSAT-C
1993 First digital satellite telephone system
1998 Global satellite systems for small mobile phones
Satellite systems hold a very promising future for global
mobile communication.
However, anything related to space is expensive, very
expensive. For the client side, the minimum hardware
cost is about $1,000. Furthermore, you need to pay the
monthly subscription fee and data transmission fee.
中華衛星一號(ROCSAT-1)發射費用為6億元!!
Mobile and Pervasive Computing Wireless Networking Essentials 57
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Application Areas (Satellite)
Traditional Weather satellites
Radio and TV broadcast satellites
Military satellites
Satellites for navigation and
localization (e.g., GPS)
Telecommunication Global telephone connections
Backbone for global networks
Connections for communication in
remote places or underdeveloped
areas
Global mobile communication
Mobile and Pervasive Computing Wireless Networking Essentials 58
Ad Hoc Networks
A local network with wireless or temporary plug-
in connection.
Mobile or portable devices are part of the
network only while they are in close proximity.
Each note is both a client and a router.
No fixed infrastructure. Information packets are
transmitted in a store-and-forward method using
peer-to-peer communication with multihop
routing.
Also abbreviated as MANET.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Ad Hoc Networks
Mobile and Pervasive Computing Wireless Networking Essentials 60
Sensor Networks
Large number of tiny sensors planted in an ad
hoc basis to sense and transmit physical
characteristics of the environment.
A BS collects the information gathered by the
sensors on a data-centric basis.
Application areas:
military applications: battlefield surveillance, …
machinery prognosis
biosensing
environmental monitoring
…
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Sensor Networks
Mobile and Pervasive Computing Wireless Networking Essentials 62
Wireless LAN and PAN
Network Range Primary Function Deployed
Locations
IEEE 30m A standard for Any P2P
802.11 wireless notes connection
HiperLAN 30m High-speed indoor Airports,
connectivity warehouses
Ad Hoc ≥500m Mobile, wireless, Battelfields,
Networks similar to wired disaster locations
connectivity
Sensor 2m Monitor inhospitable Nuclear &
Networks or inaccessible terrain chemical plants,
occean, etc.
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Mobile and Pervasive Computing Lecture04: Wireless Networking Essentials
Wireless LAN and PAN
Network Range Primary Function Deployed
Locations
HomeRF 30m Share resources, Homes
connect devices
Ricochet 30m High-speed wireless Airports, offices
Internet access (128
Kbps)
Bluetooth 10m Avoid wire clutter, Offices,
Networks provide low mobility conference room
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