Lecture02-MobilePervasivecomputing
Transcript of Lecture02-MobilePervasivecomputing
Mobile and Pervasive Mobile and Pervasive ComputingComputing
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The Mobile Commerce The Mobile Commerce LandscapeLandscape
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Mobile ComputingMobile Computing Mobile Computing Devices
Personal Digital Assistant (PDA)
A handheld computer principally used for personal information management
Smartphone
Internet-enabled cell phones that can support mobile applications
Blackberry
A handheld device principally used for e-mail
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Mobile ComputingMobile Computing Mobile Computing Software
Microbrowser
Wireless Web browser designed to operate with small screens and limited bandwidth and memory requirements
Wireless Application Protocol (WAP)
A suite of network protocols designed to enable different kinds of wireless devices to access WAP-readable files on an Internet-connected Web server
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Mobile Computing Mobile Computing LanguagesLanguages
Wireless Markup Language (WML) A scripting language used to create content in the
WAP environment; based on XML, minus unnecessary content to increase speed
Compact Hypertext Markup Language (cHTML)
A scripting language used to create content in i-mode
Extensible Hypertext Markup Language (xHTML)
A general scripting language; compatible with HTML; set by W3 Consortium
Voice XML (VXML) An extension of XML designed to accommodate voice
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WAPWAP Fixed Internet protocol:
IP –Internet Protocol: controls movement of individual pieces of information (packets) by means of routers
TCP –Transmission Control Protocol: controls movement of messages consisting of multiple packets
TCP/IP –complete set of protocols used by the Internet Problems with using TCP/IP on wireless
internet: Not developed for wireless links or mobile devices IP: router assumes next network node is same area of
network; with mobile network this may not be the case TCP: deals with lost packets by requesting that lost
packet be resent; with wireless networks connections are lost regularly and packets need to be resent often, thus congesting the system
Solution: Wireless Access Protocol (WAP)
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Wireless Application Protocol Wireless Application Protocol (WAP)(WAP)
WAP is the leading global open standard WAP is the leading global open standard
for delivery Information over wireless for delivery Information over wireless
networksnetworks
WAP provides a uniform technologies WAP provides a uniform technologies
platform with platform with consistent formatsconsistent formats for for
delivering Internet and Intranet based delivering Internet and Intranet based
Information and services to digital mobile Information and services to digital mobile
phones and other wireless devices such as phones and other wireless devices such as
pagers, smart phones and communicatorspagers, smart phones and communicators
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What WAP Can Do?What WAP Can Do?
Wireless access to Internet contentWireless access to Internet content Wireless access to Corporate IT Systems Wireless access to Corporate IT Systems
and Extranetsand Extranets Wireless access to personal informationWireless access to personal information Individuals will be able to buy theatre Individuals will be able to buy theatre
tickets, book restaurants or place bets from tickets, book restaurants or place bets from anywhere, charged to a telephone account anywhere, charged to a telephone account (MC services)(MC services)
The main news items of the day can be The main news items of the day can be delivered to mobile users on the hour (Pull)delivered to mobile users on the hour (Pull)
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WAP ArchitectureWAP Architecture
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WAP Wireless Transaction WAP Wireless Transaction ModelModel
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WAP Security ProblemWAP Security Problem
WAP gateway is weak link in security WAP gateway provides interface between WAP
protocol stack and regular internet protocol stack WAP uses WTLS (Wireless Transport Layer Security) for
security over wireless links Wired internet uses SSL (Secure Socket Layer) for
security WTLS and SSL are incompatible
Requires that wireless communication be decoded from WTLS and then encoded by SSL for communication to web server at WAP gateway
Creates potential security problem at WAP gateway
Solution: WAP 2Solution: WAP 2
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WAP 2WAP 2 Supports an alternative protocol stack that uses
SSL, not WTSL Message is encoded using SSL from mobile
client to web server with not decoding/encoding required in between
WAP gateway not needed (in theory) Provides end-to-end security Only works with faster wireless services (2.5G,
3G) that use a type of IP designed for mobile devices called Mobile IP
Use eXtensibleHTML (XHTML)
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Mobile Messaging Mobile Messaging ServicesServices
Short Message Service (SMS) A service that supports the sending and
receiving of short text messages on mobile phones
Enhanced Messaging Service (EMS) An extension of SMS that can send simple
animation, tiny pictures, sounds, and formatted text
Multimedia Messaging Service (MMS)
MMS is able to deliver rich media
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Wireless Communications Wireless Communications TechnologyTechnology
Three main categories: WWAN - Technology that supports
wireless telecommunications or wireless wide area networks
WLANWLAN - Technology that supports wireless local area networks
WPANWPAN - Technology that supports wireless personal area networks
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Wireless Communications Wireless Communications TechnologyTechnology
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WPANWPAN Personal Area Networks
Personal Area Network (PAN)
A wireless telecommunications network for device-to-device connections within a small range
Bluetooth A set of telecommunications standards that enables
wireless devices to communicate with each other over short distances
Developed by Ericsson for short range communication
Maximum speed: 721 Kbps
Maximum range: 30 meters
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WLANWLAN
Wireless Local Area Networks Wireless Local Area Network (WLAN)
A telecommunications network that enables users to make medium-range wireless connections to the Internet or another network
Wi-Fi (wireless fidelity)
The common name used to describe the IEEE 802.11 standard used on most WLANs
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WLANWLAN
Wireless Local Area Networks 802.11b
The most popular Wi-Fi standard; it is inexpensive and offers sufficient speed for most devices; however, interference can be a problem
802.11aThis Wi-Fi standard is faster than 802.11b but has a smaller range
802.11gThis fast but expensive Wi-Fi standard is mostly used in businesses
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WLANWLAN
Wireless Local Area Networks Wireless Access Point (AP)
An antenna that connects a mobile device to a wired LAN
Hotspot
An area or point where a wireless laptop or PDA can make a connection to a wireless local area network
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WLAN: IEEE 802.11b, g WLAN: IEEE 802.11b, g (Wi-Fi)(Wi-Fi)
Designed originally for notebook and desktop computer wireless communication
Maximum speed: 802.11b: 11 Mbps 802.11g: 54 Mbps
Maximum range: 500 meters Can be extended with special antennas
Has become very popular in creating wireless "hot spots" where wireless users can connect within a small radius
Most laptop computers come with built-in Wi-Ficapability
Used for Commercial WLANs (e.g., Starbucks) Public neighborhood area networks (NANs)
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How Wi-Fi WorksHow Wi-Fi Works
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WMANWMAN
Wireless Metropolitan Area Networks (WMAN)
A telecommunications network that enables users to make long-range wireless connections to the Internet or another network
WiMax
A wireless standard (IEEE 802.16) for making broadband network connections over a large area
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WMAN: 802.16e (WiMax)WMAN: 802.16e (WiMax) Proposed wireless technology for
distances within a metropolitan area (i.e., within a city)
Could be used for a metropolitan area network (MAN)
Maximum range: 5-15 km (50 km with reduced data rate)
Maximum speed: 75 Mbps Not widely available so far
Limited to telecommunications companies in France
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Wireless Wireless Telecommunications Telecommunications
NetworksNetworks
Wireless Wide Area Networks (WWAN)
A telecommunications network that offers wireless coverage over a large geographical area, typically over a cellular phone network
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Wireless NetworksWireless Networks
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Wireless Wireless Telecommunications Telecommunications
NetworksNetworks Wireless Wide Area Networks
Physical Topology of a WWAN
subscriber identification module (SIM) cardAn extractable storage card used for identification, customer location information, transaction processing, secure communications, and the like
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Cellular Telephone Cellular Telephone NetworkNetwork
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Wireless NetworksWireless Networks
WWAN Communication Bandwidths 1G - The first generation of wireless
technology, which was analog based 2G - The second generation of digital wireless
technology; accommodates voice and text 2.5G - An interim wireless technology that
can accommodate voice, text, and, limited graphics
3G - The third generation of digital wireless technology; supports rich media such as video
4G - The expected next generation of wireless technology that will provide faster display of multimedia
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WWAN Network Systems – WWAN Network Systems – Mobile Phone TechnologyMobile Phone Technology
Many mobile phone technologies Not compatible Vary in speed
First generation (1G) mobile phone technology -analog: AMPS: Advanced Mobile Phone System
Second generation (2G) mobile phone technologies - digital: FDMA: Frequency Division Multiple Access (old fashioned) TDMA: Time Division Multiple Access (US) CDMA: Code Division Multiple Access (US, Japan, China) GSM: Global System for Mobile (US, Europe)
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TDMA vs CDMATDMA vs CDMA
TDMA is slower than CDMA TDMA: 9.6 kbps CDMA: 64 kbps
CDMA is more complex than TDMA Requires code allocation, careful
synchronization CDMA is more secure than TDMA
Different codes are used by different users
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GSMGSM
There are variations of TDMA in the world
GSM uses a sophisticated variation of TDMA in which users get very short time slots: 0.577 microseconds
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Circuit switching vs. packet Circuit switching vs. packet switchingswitching
Circuit switching– User is assigned one circuit during the entire connect
time Requires long set up time (15-30 seconds) Inefficient use of bandwidth because communications
channel must be maintained for entire session duration
1G and 2G systems use circuit switching Packet switching
User sends voice/data in small groups called packets User does not have circuit assigned during entire
session duration Circuit is only used when a packet is sent More efficient use of bandwidth than circuit switching 2.5G and 3G systems use packet switching
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WWAN - Mobile Phone WWAN - Mobile Phone TechnologyTechnology
Two-and-a-half generation (2.5G) mobile phone technology: HSCSD: High-Speed Circuit-Switched Data GPRS: General Packet Radio Service EDGE: Enhanced Data GSM Environment
Third generation (3G) mobile phone technology: WCDMA or UMTS: Wideband CDMA or Universal
Mobile Telecommunications System CDMA2000
Fourth generation (4G) mobile phone technology: –?
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2.5G2.5G GPRS
Uses TDMA like GSM but channels can be allocated more than one time slot
Maximum speed: 100 kbps theoretically but 40 kbps in reality
Does not require hardware upgrade from GSM: relatively inexpensive upgrade
EDGE Uses TDMA like GSM/GPRS but uses a
technique that sends more data per time slot Maximum speed: 384 kbps Requires minor upgrades from GPRS system:
relatively inexpensive
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3G3G WCDMA/UMTS (WidebandCDMA/Universal
Mobile Telecommunications System) Uses CDMA European standard Maximum speed: 2 mbps in theory, 400 kbps in
reality Requires new spectrum (license must be purchased) Requires new equipment
CDMA Uses CDMA US standard Maximum speed: 114 kbps to 2 mbps
LBS and Pervasive LBS and Pervasive ComputingComputing
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Location-Based Service Location-Based Service (LBS)(LBS)
Location-Based Service (LBS)Delivery of m-commerce transactions to individuals in a specific location, at a specific time
The services provided through location-based m-commerce focus on five key areas:
Location Navigation Tracking Mapping Timing
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Location-Based Service Location-Based Service (LBS)(LBS)
Global Positioning System (GPS) A worldwide satellite-based tracking
system that enables users to determine their position anywhere on the earth
Geographical Information System (GIS)
An information system that integrates GPS data onto digitized map displays
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Location-Based Service Location-Based Service (LBS)(LBS)
Emergency Response Cell Phone Calls Wireless 911 (e-911)
In the United States, emergency response calls from cellular phones
Automatic Crash Notification (ACN)Device that automatically sends the police the location of a vehicle that has been involved in a crash
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Location-Based Service Location-Based Service (LBS)(LBS)
Telematics The integration of computers and wireless
communications to improve information flow using the principles of telemetry
Barriers to Location-Based M-Commerce
Accuracy of devices The cost-benefit justification Limited network bandwidth Invasion of privacy
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Pervasive ComputingPervasive Computing
Overview of Pervasive Computing Invisible, everywhere computing that is
embedded in the objects around us Principles of Pervasive Computing
• Decentralization
• Diversification
• Connectivity
• Simplicity
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Pervasive ComputingPervasive Computing
Overview of Pervasive Computing Contextual Computing
The enhancement of a user’s interactions by understanding the user, the context, and the applications and information required
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Pervasive ComputingPervasive Computing
Pervasive Computing Initiatives Radio Frequency IDentification
(RFID)
Technology that uses radio waves to identify items
Electronic Product Code (EPC)An RFID code that identifies the manufacturer, producer, version, and serial number of individual consumer products
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Pervasive ComputingPervasive Computing
Pervasive Computing Initiatives Smart Homes
• Lighting• Energy management• Water control• Home security and communications• Home entertainment
Smart Appliances Smart Cars Smart Clothes
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Pervasive ComputingPervasive Computing
Pervasive Computing Initiatives Sensor network
A series of interconnected sensors that monitor the environment in which they are placed
Sensor networks can:• Protect the environment• Public safety• Monitor business and agricultural areas
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Essay HomeworkEssay Homework
Find a recent research paper or case study in Journals about “Pervasive Computing” (Sciencedirect or Scopus)
1. Abstract – the section with title, author, journal name, and abstract
2. Description – the main findings and contribution of the article (paper/case study)
3. Conclusion – your comment about the article and suggested further research