Final Summary.doc

57 views38 pages
14 Dec 2013
Course
Professor
Chapter 7: Wireless, Mobile Computing, and Mobile Commerce
Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than
some form of wire or cable) carry the signal between communication devices (computer, PDAs, cell
phone, etc.).
Mobile Computing refers to a real-time, wireless connection between a mobile device and other
computing environments, such as the internet or an intranet.
Mobile Commerce (M-Commerce) refers to e-commerce (EC) transactions that are conducted in
wireless environment, especially via the internet.
Pervasive Computing (Ubiquitous Computing) means that virtually every object has processing
power with wireless or wired connections to a global network.
Wireless technologies include both wireless devices and wireless transmission media.
Wireless devices are small enough to easily carry or wear, have sufficient computing power to perform
productive tasks and can communicate wirelessly with the Internet and other devices.
Advantages of wireless device:
oCan make productive use of time that was formerly wasted (work in cars or public
transportation)
oWork locations become much more flexible.
oEnable to allocate working time around personal and professional obligations.
Wireless Application Protocol (WAP) is the standard that enables wireless devices with tiny display
screens, low bandwidth connections and minimal memory to access Web-based information and
services.
Microbrowsers are internet browsers with a small file size that can work within low-memory
constraints of wireless devices and the low bandwidths of wireless networks.
Wireless Devices include pages, email handhelds, PDAs, cellular phones, and smart phones.
oPager is a one-way, wireless messaging system; it alerts the user when it receives an incoming
message.
oE-mail Handhelds, such as the BlackBerry, have a small display screen and a keypad for
typing short message. E-mail Handhelds help to keep in touch with clients and the office.
oCell Phone use radio wave to provide two-way communication. The cell phone communicates
with radio antennas (towers) placed within adjacent geographic areas call cells. Cellular
technology, nowadays provides high transmission speeds and richer features (SMS, 3G, Video,
WWW), has progressed through four stages:
First generation (1G) – Analog signals and low bandwidth.
Second generation (2G) – Digital Signals for voice communication. Speed up to 10
Kbps.
2.5 G – Digital Signals for voice communication. Speed up to 144 Kbps.
Third generation (3G) – Digital Signals for voice communication. Speed up to 128
Kbps (in car), 384 Kbps (walking), and 2 Mbps (fixed).
oPersonal Digital Assistants (PDAs) are small, handheld computers that can transmit digital
communications. PDAs provide electronic schedulers, address books, emails service,
wireless internet access, camera, and voice communication (some only).
oSmart Phones are a new class of digital communication appliances (color screen and built-
in keyboard) that combine the functions of PDA and digital cell phone. Smart phones
1
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 38 pages and 3 million more documents.

Already have an account? Log in
provide organizer, cell phone, digital camera, email, internet access, Short message service
(SMS), photo, music, and video.
The smart camera phone can cause damage in workplace by easily send out company secrets.
The major types of Wireless Transmission Media are Microwave, Satellite, Radio, and Infrared.
1. Microwave transmission systems are widely used for high-volume, long-distance, point-to-
point communication. Microwave towers usually cannot be spaced more than 30 miles apart
(earth surface’s not flat) and affected by bad weather such as heavy rain or snowstorms.
Point-to-point has two characteristics: first, the transmitter and receiver must be in view of each
other (called line-of-sight); and second, the transmission itself must be tightly directed from
transmitter to receiver.
2. Satellite transmission systems make use of communication satellites; three types of satellites,
each in a different orbit:
Geostationary earth orbit (GEO) orbits 22,300 miles directly above the equator
and maintains a fixed position; excellent for TV signals.
Medium-earth-orbit (MEO) are located 6,000 miles above the earth’s surface and
move; used for GPS and are less expensive.
Low-earth-orbit (LEO) are 400 to 700 miles above the surface and move much
quicker so they require many to have adequate coverage; use for telephone.
2
Footprint is the area of earth’s
surface reached by a satellite’s
transmission – overcomes the
limitations of microwave data relay
stations.
Broadcast transmission allows
satellites to send signals to many
receivers at one time.
Propagation delay is a brief pause in
transmissions from GEO satellites
which make two-way telephone
conversations difficult.
GPS is a wireless system that uses
satellites to enable users to
determine their position anywhere
on the earth; supported by 24 shared
satellites worldwide.
Internet over Satellite (IOS) allows
users to access the Internet via GEO
satellites from a dish mounted on the
side of their homes. But, only option
available in some areas and can have
a propagation delay or be disrupted
by environmental conditions.
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 38 pages and 3 million more documents.

Already have an account? Log in
3. Radio transmission uses radio-wave frequencies to send data directly between transmitters and
receivers. Satellite radio (digital radio) offers uninterrupted, near CD-quality music that is
beamed to your radio from space. (XM satellite radio uses GEO; Sirius uses MEO).
Advantages:
radio wave travel easily through normal walls
devices are cheap and easy to install
can transmit data at high speed
Disadvantages:
radio media can create electronic interference problems
radio transmissions are affected by similar equipment that operate on the same
frequency
4. Infrared light is red light that is not commonly visible to human eyes; common uses in remote
control units for TVs, VCRs, DVDs, CD players. Infrared are also used for short-distance
connection between computer and peripheral equipment and LAN.
Wireless Computer Networks and Internet Access:
Advantages of Wireless networks:
oMobility
oNo line or cable connection needed
oAccess more current data
oSmall equipment, e.g. PDA
Advantages of Wireless networks:
oStraight line signals: must be in range
oNetwork incompatibility
oSlower transmission (this is changing)
oSmall screens/keyboards
oLess memory on PDAs
oHigh cost per minute, although this is changing
Wireless manners: ‘Rules’ for using a wireless café:
oLimit your time
oUse cell phone quietly, headphones for music
oMinimize wall socket time
oPlace cables in a safe place (ask permission to use extension cords)
oClean and non-controversial surfing
Institute of Electrical and Electronics Engineers (IEEE) standards for wireless computer networks
include:
oIEEE 802.15 (Bluetooth) for wireless personal area networks (PANs) and 802.15.4 (Zigbee).
oIEEE 802.11 (Wi-Fi) for wireless local area networks (WLANs)
oIEEE 802.16 (Wi-Max) for wireless metropolitan area networks (WMANs)
oIEEE 802.20 (proposed) for wireless wide area networks (WWANs) – still under development.
Impact of multiple standards:
oDifficult to exchange wireless information from different standards, e.g. BlueTooth to WiFi,
Cell phones to laptops
3
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 38 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Grade+

Unlimited access to all notes and study guides.

Grade+All Inclusive
$10 USD/m
You will be charged $120 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.