Post on 19-Dec-2015
CS 6910 – Pervasive ComputingSpring 2007
Section 1 (Ch.1):
Introduction toWireless and Mobile Systems
Prof. Leszek LilienDepartment of Computer Science
Western Michigan University
Slides based on publisher’s slides for 1st and 2nd edition of: Introduction to Wireless and Mobile Systems by Agrawal & Zeng© 2003, 2006, Dharma P. Agrawal and Qing-An Zeng. All rights
reserved.
Some original slides were modified by L. Lilien, who strived to make such modifications clearly visible. Some slides were added by L. Lilien, and are © 2006-2007 by Leszek T. Lilien. Requests to use L. Lilien’s slides for non-profit
purposes will be gladly granted upon a written request.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 2
Chapter 1
INTRODUCTION
[Image of 2nd ed. cover added by L. Lilien.]
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 3
Evolution Distributed Computing (DIST)
Originally wireline only Wireless Computing
Originally non-mobile wireless only Mobile Computing (MOBI)
Really: Wireless & Mobile Computing Pervasive Computing (PERV)
Note: Textbook uses “wireless” and “mobile” as synonyms
Not precise: e.g., can have wireless but not mobile
Q: Why to study Wireless & Mobile Computing?A: It is foundation for PERV, its critical technology &
building block Some other technologies for Pervasive Computing:
Embedded computing Sensornets Opportunistic networks (oppnets) and systems
See Lecture Section 0.B
© 2007 by Leszek T. Lilien
Pervasive vs. Wireless & Mobile Systems
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 4
1.1. The History of Mobile Radio Communication (1/3)
1880: Hertz – Initial demonstration of practical radio communication 1897: Marconi – Radio transmission to a tugboat over an 18 mi path 1921: Detroit Police Department: -- Police car radio dispatch (2 MHz
frequency band) 1933: FCC (Federal Communications Commission) – Authorized four
channels in the 30 to 40 MHz range 1938: FCC – Ruled for regular service 1946: Bell Telephone Laboratories – 152 MHz (Simplex) 1956: FCC – 450 MHz (Simplex) 1959: Bell Telephone Laboratories – Suggested 32 MHz band for high
capacity mobile radio communication 1964: FCC – 152 MHz (Full Duplex) 1964: Bell Telephone Laboratories – Active research at 800 MHz 1969: FCC – 450 MHz (Full Duplex) 1974: FCC – 40 MHz bandwidth allocation in the 800 to 900 MHz range 1981: FCC – Release of cellular land mobile phone service in the 40 MHz
bandwidth in the 800 to 900 MHz range for commercial operation
Emphasis (underlines) on this and next 2 slides added by LTL
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The History of Mobile Radio Communication (2/3) 1981: AT&T and RCC (Radio Common Carrier) reach an agreement to
split 40 MHz spectrum into two 20 MHz bands. Band A belongs to nonwireline operators (RCC), and Band B belongs to wireline operators (telephone companies). Each market has two operators.
1982: AT&T is divested, and seven RBOCs (Regional Bell Operating Companies) are formed to manage the cellular operations
1982: MFJ (Modified Final Judgment) is issued by the government DOJ [LTL: Dept of Justice]. All the operators [LTL: RBOCs] were prohibited to (1)
operate long-distance business, (2) provide information services, and (3) do manufacturing business
1983: Ameritech system in operation in Chicago 1984: Most RBOC markets in operation 1986: FCC allocates 5 MHz in extended band 1987: FCC makes lottery on the small MSA [LTL: Metropolitan Statistical
Area] and all RSA [LTL: Rural Service Area] licenses 1988: TDMA (Time Division Multiple Access) voted as a digital cellular
standard in North America 1992: GSM (Groupe Speciale Mobile) operable in Germany D2 system
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The History of Mobile Radio Communication (3/3) 1993: CDMA (Code Division Multiple Access) voted as another digital
cellular standard in North America 1994: American TDMA operable in Seattle, Washington 1994: PDC (Personal Digital Cellular) operable in Tokyo, Japan 1994: Two of six broadband PCS (Personal Communication Service) license
bands in auction 1995: CDMA operable in Hong Kong 1996: US Congress passes Telecommunication Reform Act Bill 1996: The auction money for six broadband PCS licensed bands (120 MHz)
almost reaches 20 billion US dollars 1997: Broadband CDMA considered as one of the third generation mobile
communication technologies for UMTS (Universal Mobile Telecommu-nication Systems)
During the UMTS workshop conference held in Korea 1999: ITU (International Telecommunication Union) decides the next
generation mobile communication systems (e.g., W-CDMA, cdma2000, etc.) 2001: W-CDMA commercial service beginning from October in Japan 2002: FCC approves additional frequency band for Ultra-Wideband (UWB)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 7
[LTL:]
RF = radio frequency
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Applications[LTL:] Wireless Telephone
Cincinnati, OH
Washington, DC
[LTL:] User moves but phone # unchanged
Maintaining the telephone number across geographical areas in a wireless and mobile system
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 10
1G - First Generation Primarily for voice communication Using FDM (frequency division multiplexing)
2G - Second Generation Emphasis still on voice communication but allows for… … Data communication Using TDM (time division multiplexing) Indoor/outdoor and vehicular environment
3G - Third Generation Integrated voice, data, and multimedia communication Need for:
High volume of traffic / Real time data communication Flexibility, incl.
Frequent Internet access Multimedia data transfer
Compatibility with 2G Using compression
Without compromising quality
© 2007 by Leszek T. Lilien
Generations of Wireless Systems & Services
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 11
First Generation Wireless Systems and Services
1970s Developments of radio and computer technologies for 800/900 MHz mobile communications [1st mobile band]
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) [cellular] introduced by AT&T in North America
Emphasis (underlines) and text in square brackets on this and next slide added by LTL
Note: “Cellular systems” called “mobile systems” outside North America.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 12
Second Generation Wireless Systems and Services1982 CEPT (Conference Europeenne des Post et Telecommunications)
established GSM [global special mobile] to define future Pan-European Cellular Radio Standards
1990 Interim Standard IS-54 (USDC [US digital cellular]) adopted by TIA (Telecommunications Industry Association)
1990 Interim Std IS-19B (NAMPS [narrowband AMPS]) adopted by TIA
1991 Japanese PDC (Personal Digital Cellular) system standardized by the MPT (Ministry of Posts and Telecommunications)
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 [added 2nd band (1900 MHz)] issued in North America
1996 Phase II GSM operational
1997 North American PCS deploys GSM, IS-54, IS-95
1999 IS-54: in North AmericaIS-95: in North America, Hong Kong, Israel, Japan, China, etcGSM: in 110 countries
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Basic technology in the U.S. cdma2000
Basic technology in Europe & Japan W-CDMA
Similar but design & implementation differences
© 2007 by Leszek T. Lilien
Two Basic Technology Choices for 3G
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 14
Third Generation Wireless Systems and Services (1/2)
IMT-2000 (International Mobile Telecommunications-2000):
- Fulfill one's dream of anywhere, anytime communications a reality.
Key Features of IMT-2000 include:
- 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.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 15
Third Generation Wireless Systems and Services (2/2)
Important Component of IMT-2000 is ability to provide high bearer rate capabilities:
- 2 Mbps for fixed environment;- 384 Kbps for indoor/outdoor and pedestrian
environments;- 144 Kbps for vehicular environment.
Standardization Work:- Release 1999 specifications- In processing
Scheduled Service: - Started in October 2001 in Japan (W-CDMA)
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Future: 4G 4G
Expected to implement all standards from 2G & 3G Infrastructure only packet-based, all-IP Some of the standards paving the way for 4G:
WiMax WiBro (Korean) 3GPP Long Term Evolution
To improves the UMTS mobile phone standard Work-in-progress technologies
E.g., HSOPA, a part of 3GPP Long Term Evolutionon
© 2007 by Leszek T. Lilien
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 17
Subscriber Growth for Wireless Phones
3G Subscribers
2G Digital-only Subscribers
1G Analog-only Subscribers
Subs
crib
ers
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Year
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China Leads World in Mobile Phone Users
Total [World] Mobile Users > 800 million [2003] Total [World] Analogue Users > 70 million [2003]
ZDNet UK reports that the number of mobile phone users in China reached 167 million in April, 2002, a rise of 6 million subscribers on March, 2002.
The US, which is the second biggest market, has 136 million subscribers.
Mobile phones are the preferred mode of communication in Japan, with 56.8 million subscribers as of the end of March, 2003.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 19
Many diverse subsystems Different requirements for different needs Different characteristics
Corresponding to the requirements Different coverage areas
Cell = area that can be covered by a single transmitting station (usually called base station) Picocells, microcells, macrocells & global “cell”
Figure – next slide
Why different cell sizes? Limited nr of channels per cell Smaller cells can serve more users
E.g. 2x smaller => can serve 2x more users on the same band (with smaller range)
© 2007 by Leszek T. Lilien
Flexibility & Versatility of 3G
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 20
Coverage Aspect of Next Generation Mobile Communication Systems
Picocell Microcell Macrocell Global
Urban
Suburban
Global
Satellite
In-Building
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 21
Transmission Capacity as a Function of Mobility
Broadband radio
Glo
bal S
yste
m f
or M
obil
e C
omm
unic
atio
ns
0.01 0.1 1 10 100
Transmission capacity as a function of mobility in some radio access systems
Mob
ilit
y
Universal Mobile Telecommunica- tions System
Mobile Broadband System
Broadband Satellite Multimedia
Local Multipoint Distribution System
Satellite Universal Mo-bile Telecommunica- tions System
Data Rate (Mb/s)
Stationary
Pedestrian
Vehicular
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1.2. Characteristics of Cellular SystemsWireless Technology & Associated Characteristics
Wireless Technologies Cellular WLAN (Wireless LAN) GPS Satellite Based PCS Campus network (e.g., Ricochet, Carnegie Mellon U.) Home Networking Ad Hoc Networks WPAN (Wireless PAN = [personal area network])
Incl. Bluetooth Sensor Networks
Different technologies needed for different applications
-- Details on the next slide –
[From 1st ed. slides – Slightly modified by LTL]
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 23
[LTL: Yellow and red highlights added]
(phone calls)
(CMU campus)
(also oppnets, IANs)
(WPAN = wireless personal area network)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 24
Wireless Technologies for Application Classes
[LTL: Yellow and red highlights added]
Notice the following: Infrastructure-based networks vs. ad hoc networks
(p. 11/2)
Terms & acronyms: Access point – AP (p. 8/-1, 10/2) Mobile station – MS (p. 11/2) Handoff and switching radio resources (p. 11/3)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 25
Application Example: Medical Application
Wireless remote consultation
ATM backbone network
ATM backbone network
Possibility for remote consulting(including audio visual communication)
ATM switch
ATM switch
Remote databases
In hospitalphysician
Ambulance
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Wireless Features & Their Potential Apps
[LTL:] Notice the following (p. 11/-1):
“Anytime anywhere” not always required Often “many time” or “many where” is adeqate
Permanent connectivity not necessary MS can:
Start transaction at AP1, then move away (loosing connection to it) Get close to AP99 & complete transaction at AP99
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1.3. Fundamentals of Cellular Systems
Illustration of a cell with a mobile station (MS) and a base station (BS)
BS
MS
Cell
Hexagonal cell area used in most models
Ideal cell area (2-10 km radius)
(circle)
Alterative shape of a cell
(square)
MS
[LTL:]
Cell shapes (above) Actually, cell may have a zigzag shape Hexagon is a good approximation in practice
Also, gives non-overlapping cells (used by clever bees for beehives)
E.g., circles would either overlap, or would have gaps in between
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 28
Single BS per cell =>limited bandwidth per cell
Increase bandwidth useefficiency by multiplexing
4 +1 basic multiplexing techniques FDMA – frequency division multiple access TDMA – time division multiple access CDMA – code division multiple access OFDM – orthogonal frequency division multiplexing New: SDMA – space division multiple access
Specialized for microwave antennas
© 2007 by Leszek T. Lilien
Cell Bandwidth Limitations & Multiplexing
BS
Service area
(Zone)
MS
MS
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FDMA (Frequency Division Multiple Access)
User 1
User 2
User n
…
Time
Frequency
[LTL:]
Used in all 1G cellular systems BS allocates to each of n users a channel (a
frequency subband) for time the user needs it
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FDMA Bandwidth Structure
1 2 3 … nFrequency
Total bandwidth[LTL:] Divided into n channels
(frequency subbands)
4
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FDMA Channel Allocation
Channel 1 User 1
Channel 2 User 2
Channel n User n
Base Station
… …
Mobile Stations
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TDMA (Time Division Multiple Access)
Use
r 1
Use
r 2
Use
r n
…
Time
Frequency
[LTL:]
Used in most 2G cellular systems BS allocates to each user full bandwidth for
duration of a time slot
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TDMA Frame Structure
1 2 3 … nTime
Frame
[LTL:] Divided into n time slots(by a round-robin method)
4
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TDMA Frame Illustration for Multiple Users
Time 1
Time 2
Time n……
Base Station
User 1
User 2
User n
…
n Mobile Stations
[LTL:]
Note: Non-overlapping time slices “Time 2” slot starts after “Time 1” slot is over, etc.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 35
CDMA a.k.a. spread spectrum technique Used in some 2G and most 3G cellular systems
Simultaneous transmission of data from multiple users on full frequency band Figure shows all users using:
Same range of frequencies Same time rangeBut Different codes
CDMA is enabled by orthogonalcodes (= keys) One distinct code assigned
by BS to each user
© 2007 by Leszek T. Lilien
CDMA (Code Division Multiple Access)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 36
CDMA transmission Transmitter:
Codes (using the key) each user’s data “stream” Puts all coded individual data “streams” on data link
Creates a common “mixed” data stream
Receiver: Gets common “mixed” data stream from data link Uses keys to decode (“unmix”) individual data stream
from the “mixed” data stream
# of simultaneous users limited by # of possible orthogonal codes
Complex but robust technique
© 2007 by Leszek T. Lilien
CDMA (Code Division Multiple Access) – cont.
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 37
[SKIP:] Transmitted & Received Signalsin a CDMA System
Information bits
Code at transmitting end
Transmitted signal
Received signal
Code at receiving end
Decoded signal at the receiver
[LTL:] 10-bit codewords
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Frequency Ranges used forFDMA, TDMA & CDMA
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OFDM idea – to reduce interference Convert single high-speed data stream to multiple
low-speed data streams Low-speed data streams sent in parallel using
(sub)channels working on multiple-frequencies
Frequencies of subchannels in FDMA vs. OFDM FDMA – non-overlapping frequen-
cies of subchannels Even with gaps between subchannel
bands to reduce interference OFDM - overlapping frequencies
of subchannels
© 2007 by Leszek T. Lilien
OFDM (Orthogonal Frequency Division Multiplexing)
Figure: Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng.
All rights reserved
39
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Many variants & combinations of FDMA, TDMA & CDMA - beyond the scope of this discussion
Frequency hopping – combines FDMA & TDMA
Idea: One user uses one channel for a time slot, then changes to another channel for another time slot
See the next slide Receiver needs to know frequency hopping
sequence
Main advantage (e.g., in defense applications):Message gets through even if one frequency band jammed
© 2007 by Leszek T. Lilien
Variants & Combinations ofFDMA, TDMA & CDMA
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Frequency Hopping
Frequency
f5
f4
f3
f2
f1
Frame Slot
Time
[LTL:] Each user gets one time slot per frame, on a different frequency (round-robin used for frequency selection)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 42
1.4. Cellular System Infrastructure
BS
Service area (Zone)
Early wireless system: Large zone
[LTL:]
Large zone requires a high-power BS Better: replace large zone with smaller hexagonal
zones (next slide)
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Cellular System: Small Zone
BS BS
BS BS BS
BS BS
Service area
[LTL:]
BS covers much smaller area now Requires much less power (for a given area)
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Various kinds of Mobile Stations (MSs) a.k.a. wireless devices
Cellphone, PDA, PalmPilot, laptop with WiFi card, …
MSs need connectivity on the move E.g., connectivity from BSs in the cells they visit
BS is a gateway to wired infrastructure
Typical support for MSs: Cellular infrastructure See next slide
© 2007 by Leszek T. Lilien
Cellular System Infrastructure
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Home phone
PSTN
MSC
BSC …
BS
…
…
MS
…
BS MS
BSC
BS MS
…
BS MS
BSC
BS MS
…
BS MS
BSC
BS MS
…
BS MS
MSC
MS, BS, BSC, MSC, and PSTN
[LTL:] Several BSs connected via wireline links to one BSC (BS
controller) Several BSCs connected via wireline links to one MSC (Mobile
Switching Center) Several MSCs interconnected via wireline links to PSTN (Public
Switched Telephone Network) and the ATM backbone
wired link
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BS consists of Base Tranceiver System (BTS)
Includes tower & antenna BSC
Contains all associated electronics
© 2007 by Leszek T. Lilien
BS Structure
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MSC database for supporting MS mobility1) Home location register (HLR) for MS
Located at the “home MSC” for MS Where MS is registered, billed, etc.
Indicates current location of MS Could be within home MSC’s areaOR Could be in the area of any MSC in the world
2) Visitor location register (VLR) on each MSC Contains info on all MSs visiting area of this MSC
Incoming call scenario Based on the called #, incoming call for an MS is
directed to the HLR of the “home MSC” for this MS HLR redirects the call to MSC/BSC/BS where the MS is
now VLR of the “current MSC” has info on MS (one of visiting MSs)
© 2007 by Leszek T. Lilien
MSC Database Supporting MS Mobility & Incoming Call Scenario
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Control and Traffic Channels
Base Station
Forward
(downlin
k) contro
l channel
Mobile Station
Reverse (
uplink) c
ontrol c
hannel
Forward
(downlin
k) traff
ic channel
Reverse (
uplink) tr
affic
channel
Note: Forward/reverse in the U.S., downlink/uplink elsewhere
[LTL:]
4 simplex channels needed for control & traffic 2 control channels
Exchange control msgs Forward channel & reverse channel
2 traffic channels For data Forward channel & reverse channel
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 49
More on Control and Traffic Channels
[LTL:]
Traffic channels used for call duration => Large # of traffic channels on each BS
Handshake steps for call setup use control channels
Control channels used for short duration => Small # of control channels on each BS MSs compete for these few control channels
For call setup, etc.
© 2007 by Leszek T. Lilien
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 50
Steps for a Call Setup from MS to BS
BS MS
1. Need to establish path
2. Frequency/time slot/code assigned
(FDMA/TDMA/CDMA)
3. Control information acknowledgement
4. Start communic. on assigned traffic channel
[LTL:]
Steps for a call setup from MS to BS - When MS initiates a call
Tim
e
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Steps for a Call Setup from BS to MS
BS MS
2. Ready to establish a path
3. Use frequency / time slot / code
(FDMA/TDMA/CDMA)
4. Ready for communication
5. Start communic on assigned traffic channel
1. Call for MS # pending
[LTL:]
Steps for a call setup from BS to MS: When MS responds to a call (somebody calls MS)
Tim
e
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A Simplified Wireless Communication System Representation
Information to be transmitted (Voice/Data)
Coding Modulator Transmitter
Information received
(Voice/Data)
Decoding Demodulator Receiver
Antenna
AntennaCarrier
Carrier
[LTL:]
The figure shows major steps in wireless communications Signal processing operations – beyond the lecture scope Lecture will concentrate on system aspects of wireless
data communication
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1.5. Satellite Systems Application areas of satellite systems
Traditional Applications Weather satellite Radio and TV broadcasting Military satellites Navigation and localization (e.g., GPS)
Telecommunication Applications Global telephone connections Backbone for global network Connections for communication in remote places or
underdeveloped areas Global mobile communications
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 54
Basic Concepts & Terminology Only LOS communication is possible
LOS = line of sight Satellites further away from earth cover a wider area Satelites can emit one or more satellite beams
Satellites w.r.t. position over earth Geostationary Rotating around the earth
ES – earth station
© 2007 by Leszek T. Lilien
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 55
History of Satellite Systems
50th anniversary of the space age on October 4, 2007
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1.6. Network Architectures and Protocols
[LTL:] Protocol = basic set of rules followed to provide systematic signaling steps for information exchange Other protocols:
Diplomatic protocols, protocol to login, … [LTL:] We will cover later following protocol
reference models and protocols: Open Systems Interconnections (OSI) reference
model Transmission Control Protocol (TCP) (on top of IP)
Internet Protocol (IP) Internet Protocol Version 4 (IPv4) Internet Protocol Version 6 (IPv6) – work in progress Mobile IP (MIP)
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 57
1.7. Ad Hoc Network [LTL:] Ad hoc network (AHN) Def 1: AHN is a local network with wireless connections or
temporary plug-in connections, in which mobile or portable device are a part of the network only while they are in close proximity
Def 2: AHN is a collection of wireless MHs forming a temporary network without the aid of any centralized administration or standard support services regularly available on the wide area network (WAN) to which the hosts may normally be connected
Examples: AHN 1: Instructor’s and students’ computers can create an AHN
during lectures AHN 2: Oppnet used after an earthquake
© 2007 by Leszek T. Lilien
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 58
1.7. MANET
Source
Destination
[LTL:] MANET = mobile ad hoc network - an autonomous system of mobile nodes, mobile hosts (MHs), or mobile stations (MSs) connected by wireless links
MSs of a MANET also serve as routers These routers are mobile Route messages from SRC to DEST - see Figure
Multihop routing Store-and-forward passing of info in P2P (peer-to-
peer) way
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 59
MANETs – cont.1
MANETs are highly dynamic All nodes, incl. routers, are mobile
=> topology highly dynamic, unpredictable Topology change due to MSs mobility made known
to (some) other nodes Types w.r.t. infrastructure support
Stand alone - no infrastructure support Limited infrastructure support
Some routers have access to a fixed infrastructure
E.g., access to Internet – like in oppnets E.g., stub network (SN) –
Stub network = a single LAN which never carries packets between two remote hosts; all traffic is to and/or from local hosts
Multiple routers on SN don't route to one another, they will only route a packet into SN (if it's destined for SN), and out from SN (if it originated on SN) [cf. “stub network“ in Wikipedia]
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 60
MANETs – cont.2
Location of MSs in a MANET: within buildings, highways, vehicles, on and within human bodies
MANET nodes equipped with a “radio”“Radio” = wireless transmitter & receiver (or: wireless transceiver) With antenna
Types of antennas: Omnidirectional Directional Steerable Any combination of these
Xmit/rcv parameters affect MANET topology at any given moment
Copyright © 2003, Dharma P. Agrawal and Qing-An Zeng. All rights reserved 61
Wireless Sensor Networks
Base Station
Antenna
SensorTarget
[LTL:] (Ad Hoc) Wireless Sensor Networks (WSNs) – a specia-lized subclass of AHNs Sensor(s) in each node in addition to processor and
radio Sensors sense/measure some physical characteristcs
Temperature, humidity, acceleration, pressure, toxicity, … Can be planted at random
Even thrown out of a speedingvehicle, even from a plane
Note: The plane in the Figureis BS & collects data. Anotherone could have droppedsensor nodes earlier
BS collects &aggregatessensed info
Example 1 (Fig):Sensing enemy’smoves
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Example 2: Sensing a Cloud of Smoke
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1.8. Wireless LAN and PAN
IEEE 802.11 = Wireless Local Area Network (WLAN) using the IEEE 802.11
HiperLAN is a European Standard Bluetooth nets are examples of Wireless Personal Area Networks
(WPAN)