Transcript Telecommunications, the Internet, and Wireless Technology Chapter Seven (10 ed)

Telecommunications, the Internet,
and Wireless Technology
Chapter Seven (10th ed)
Why Is Business Interested in
Telecommunication and Networking?
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Declining transaction costs (benefits of B2C and
B2B)
Declining agency costs because managers can
monitor employees and markets remotely
Increased agility (connections with suppliers and
customers enables managers to spot trends and
take appropriate actions). Concepts like
extranets, collaborative commerce, intranets
support this idea.
Higher quality management decisions (access to
more information in a timely manner)
Declining geographical barriers
Declining temporal barriers (software
development, time-based competition)
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Telecommunications and Networking
in Today’s Business World
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Prior to 1990 most business communication
 Postal service
 Telephone system (voice & fax)
Today most business communication is
 Computers and email using the Internet
 Cellular telephones
 Mobile computers using wireless connections
All business has become “e-business”
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Magnitude of the Change
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1 billion instant messages per day
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4 billion e-mails each day
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65 million music files downloaded
Estimated 3.9 billion photos sent over the
Internet
$769 billion spent in the United States on
telecommunications equipment and services
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Telecommunications spending in the
United States, 2002–2007
Note differences between services and equipment spending
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Basic Network Components
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A network consists of two or more connected
computers.
A network interface device (NIC) is the
connection point between one computer and the
network
A network operating system (NOS) routes and
manages communications on the network and
coordinates network resources (saving or
retrieving files on your hard drive versus a
network drive)
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Basic Network Components
(continued)
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Hubs connect network components, sending a
packet of data to all other connected devices
A switch has more intelligence than a hub and can
forward data to a specified device or destination.
The switch is used within a given network to
move information.
Unlike a switch, a router (bridge) is a special
communications processor used to route packets
of data through different networks, ensuring that
the message sent gets to the correct address. A
router connects a LAN to the Internet.
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A Simple Network
Figure 8-4
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Corporate Network Infrastructure
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Pieces in the Corporate Infrastructure
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Center piece is a collection of linked LANS that
support a firm wide corporate network
A series of servers supporting a corporate web
site linked to enterprise and legacy systems
Support for a mobile sales force
Separate telephone network (cell and landline)
Separate video conferencing system (not shown)
Currently no one vendor can supply all of the
services required
How does a manager navigate through this
complex environment and make the right
decisions?
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Data and Signals
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Digital data (1’s and 0’s) are represented by a
discrete non-continuous wave form.
Analog data is represented by a continuous wave
form. The human voice, music, and noise are
examples of analog data.
From a physical point of view, data can converted
to an electric (carried over a wire) or
electromagnetic (stream of photons) signal
Usually digital signals convey digital data and
analog signals convey analog data.
In telecommunications there is a need to convert
digital data to an analog signal and vice versa.
Computers emit digital data but parts of the
telephone system only transmit analog signals, so
digital data must be converted into an analog
signal and vice versa (need for your modem)
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More on Signals
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All signals can be represented as a sine wave (curve).
The amplitude of a sine wave is the maximum height of the
sine wave from the x-axis
The frequency of a sine wave is the number of times a sine
wave makes a complete cycle within a given time frame.
Cycles per second is referred to as Hertz (Hz)
Digital data can be converted to a digital signal by using
two different voltages.
Digital data can be converted to an analog signal by using
either two different frequencies or two different
amplitudes.
The greater the frequency of a signal, the higher the
possible data transfer rate; the higher the desired data
transfer rate, the greater the need signal frequency.
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Electromagnetic Signals
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Electromagnetic signals can be described in terms
of a stream of photons each traveling in a wavelike pattern, moving at the speed of light and
carrying some amount of energy. The only
difference between radio waves, visible light, and
gamma-rays is the energy of the photons. Radio
waves have photons with low energies,
microwaves have a little more energy than radio
waves, infrared has still more, then visible, Xrays, and gamma-rays. Low energy photons (such
as radio) behave more like waves, while higher
energy photons (such as X-rays) behave more like
particles.
The electromagnetic spectrum can be expressed
in terms of energy, wavelength, or frequency.
Each way of thinking about the EM spectrum is
related to the others in a precise mathematical
way (see next slide).
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The Relationship Between Wave
Length and Frequency
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Modulation
Figure 6.8 Signal modulation
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Frequency Spectrum for
Electromagnetic Signals
ELF
VLF
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LF
1K
MF
100K
HF
1M1M
VHF
10M
UHF
100M
Microwave Optical
1G
Hertz
10G
All waves behave
similarly
Frequency differences
 Amount of data
 Distance
 Interference /
Noise
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Client/Server Computing
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The hardware side
 The client
 The server
The software side
 Client/server software splits the processing of
applications between the client and server to
take advantage of strengths of each machine
 E-mail and browsers are examples
Client/server computing has largely replaced
centralized mainframe computing
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Packet Switching
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In packet-switched networks, messages are first
broken down into small bundles of data called
packets that are sent along different
communication paths and then reassembled once
they reach their destinations.
Packet switching makes more efficient use of the
communications capacity of a network.
The packets include information for directing the
packet to the right address and for checking
transmission errors along with the data.
Always done on the Internet, but restricted to
data now being used for voice (VoIP)
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Packet Switching
Figure 8-5
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TCP/IP
• TCP/IP is the communications protocol used by
the Internet and all Internet devices.
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TCP (transmission control protocol) part
 Handles the movement of data between
computers
 Establishes a connection between the
computers, sequences the transfer of packets,
and acknowledges the packets sent
IP (Internet protocol) part
 Responsible for the delivery of packets
 Includes the disassembling and reassembling
of packets during transmission
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Internet Protocol Numbers (IPv4)
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Each device attached to the Internet has an IP number (some
static/some dynamic)
Each IP number consists of four parts separated by periods. Each
part contains a number between 0 and 255 therefore each part
can be represented by 8 bits or 32 bits for the entire IP number
(e.g., 146.186.87.220).
Approximate number of devices able to be on the Internet is 232
or
210* 210* 210*22~103*103*103*22=109*4 (4 billion)
The process of associating an IP number with a character based
name is called domain name resolution. The domain name system
(DNS) is the software that associates character based names with
the IP number. Internet Service Providers (ISPs) usually dedicate
a server to perform domain name resolution (i.e., a DNS server).
To determine speed of your connection: http://www.ipadress.com/speedtest/
To determine your IP number: http://www.What
ismyIpaddress.com
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Transmission Media – Wire Or Wireless
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Wire media
 Twisted Wire – up to 100Mbps
 Coaxial Cable – up to 1 Gbps
 Fiber Optics – up to 6+Tbps
 Uses strands of glass and pulses of light
 Most expansive of three – can carry data,
voice, and video efficiently
Wireless media
 Terrestrial microwave 100 +Mbps
 Satellite microwave GEO (geostationary earth
orbit); about 22,000 miles above earth
 Satellite microwave LEO (low earth orbit);
about 400-1000 miles above earth
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Transmission Speeds
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Digital signal speeds are usually expressed in bits
per second (Kbps, Mbps, and Gbps).
Analog signal speeds are usually expressed in
frequency per second or Hertz (KHz, MHz, or
GHz).
A simple relationship between bps and frequency
is found in Nyquist’s theorem
 C=2*f*(log2)*L where f is the frequency, L is
the number of signal levels (often 2) and C is
the capacity of the medium in bps
The range of frequencies accommodated on a
particular medium is called its bandwidth. For
example, current cell phones operate in a
bandwidth between 1.85 GHz and 2.2 GHz
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Multiplexing Concept
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A channels is a path followed by a flow of
information (stream of bits). The information is
carried by a digital or analog signal.
Multiplexing involves using a single
communications channel to carry simultaneous
transmissions from multiple sources.
Examples
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Frequency division multiplexing divides a high speed
channel into multiple channels of slower speeds (FDMA –
code division multiple access)
Time division multiplexing assigns the sender
transmitter a small slice of time to use the high speed
channel (TDMA)
Code division multiplexing assigns each user a special
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code enabling multiple users on a single channel (CDMA)
Types of Networks by Geographic
Scope
Type
Local Area Network (LAN)
Campus Area Network (CAN)
Metropolitan Area Network
(MAN)
Wide Area Network (WAN)
Area
Up to 500 meters (half a mile); an
office or floor of a building
Up to 1,000 meters (a mile); a college
campus or corporate facility
A city or metropolitan area
Transcontinental or global area
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LANs
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Typical LAN operating systems are Windows (based), Linux,
or Novell each supports TCP/IP (ease of establishing an
intranet)
Ethernet is a LAN standard contained on the NIC
LANs may use the client-server or peer-to-peer architecture
(all computers can share resources directly)
In the client-server model
 NOS is primarily on the server
 Large LANs often have many servers each dedicated to a
specific function (e.g., print server, file server, Web
server)
LAN topologies (shapes)
 Star
 Bus
 Ring
Wired LANs versus wireless LANs
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LAN Topologies
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Broadband Network Services and
Technologies
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These technologies are for high-speed
transmission or access to the Internet and
provided by telecom companies
Services
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Frame relay is like packet switching but faster
Digital subscriber lines (DSL) operate over existing
phone lines and carry voice, data, and video. Provided
by phone company
Cable internet connection is provided by cable tv
vendors using same wires used for cable tv
T1 lines are high speed high volume lines supplied by
telephone companies that are used by firms to move
large volumes of voice and data traffic with strong
security and reliability
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Broadband Network Services and
Technologies (continued)
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Asynchronous transfer mode (ATM) is a packet
switching technology that can pass data among
computers from different vendors and handle
data, video, and audio over the same network.
ATM creates a fixed channel, or route, between
two points whenever data transfer begins. This
differs from TCP/IP, in which messages are
divided into packets and each packet can take a
different route from source to destination. This
difference makes it easier to track and bill data
usage across an ATM network, but it makes it less
adaptable to sudden surges in network traffic.
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Internet Governance
• No one “owns” the Internet, but worldwide
Internet policies are established by the
following organizations:
Internet Architecture Board (IAB)
 Internet Corporation for Assigned Names
and Numbers (www.ICANN.org )
 Internet Network Information Center
(InterNIC)
 Internet Engineering Steering Group (IESG)
 Internet Engineering Task Force (IETF)
 Internet Society (ISOC)
 World Wide Web Consortium -www.W3C.org
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Future of the Internet
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Internet Protocol version 6 (IPv6): 128-bit
addresses, contains over a quadrillion possible
unique addresses
Internet2 and Next-Generation Internet (NGI)
are consortia working on the next generation
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Internet Technologies with Business
Implications
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Chatting and instant messaging
Electronic discussion groups (Usenet)
Groupware
Electronic conferencing
Internet telephony
Virtual private networks
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Unique Features of the Internet
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The World Wide Web
Client/Server Computing on the Internet
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The World Wide Web
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Terms associated with the Web
HTML
HTTP
URL – ttp://www.megacorp.com/content/features/08602.html
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www.megacorp.com is the name of a Web server holding the info
Content/features is the directory path
08602.html is the name of the file and file format (html)
Search engines and search engine marketing
(www.google.com)
Intelligent agents (shopping bots)
 www.froogle.com or www.mysimon.com
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The World Wide Web continued
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Web 2.0 refers to second-generation interactive
Internet based services
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Mashups (see chapter 5)
Blog (short for Weblog) is a Web site where subscribing
individuals can publish material and links to other Web
sites of interest. Business applications?
www.diabetesblognetwork.com
RSS (rich site summary) enables users to check for
updates to a site. If a user subscribes to the RSS service
of a site, then the site notifies the user about new
content on the site (garageband.com)
Podcasting is like blogging except you are publishing
sound (www.abc.com)
Wikis are like blogs but visitors can change the posted
material (Wikipedia)
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Intranets
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An intranet is a computer network within an
organization that uses Internet technologies for
members of the organization only
If a company has an existing network, than
establishing an intranet is very inexpensive. All
that is required is the server software and
browsers for clients.
Most of the technologies mentioned earlier are all
available at no charge
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Information Most Frequently Found in
Corporate Intranets
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Customer databases
Corporate policies and procedures (Winthrop)
Corporate phone directories
Human resource forms (Winthrop)
Training programs
Product catalogs and manuals (Winthrop)
Data warehouse and decision support access
Internal purchase orders (Winthrop)
Travel reservations
Knowledge management databases
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Extranets
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An extranet is similar to an intranet but it enables
the firm’s business partners (e.g., suppliers or
customers) to access the firm’s intranet
Once an organization links its network to the
Internet theoretically anyone can access the
firm’s network. With respect to an extranet, firms
want to restrict access to business partners. A
virtual private network provides the security
mechanism for accomplishing this. A VPN uses a
combination of public and private lines to build a
secure extranet. The link between the firm’s
network and the Internet is often called a
“tunnel.” A VPN provides a secure tunnel.
VPNs are also required for firms with extensive
intranets (multi-site firms)
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Extranet Applications
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Managing the supply chain
Collaborating with other organizations in the
development of new products/services
Sharing product catalogs exclusively with
wholesalers
Sharing news and other information of shared
interest exclusively with business partners (e.g.,
production schedules, forecasts)
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Wireless Communications and Access
to the Internet
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Wireless devices
 (A devices) Cell phones, handheld computers (PDA),
email handhelds, and smart phones
 (B devices) PCs (laptops or desktops)
Standards for A devices
 Cell phone standards (voice)
 Global System for Mobile Communication (GSM)is an
international standard
 Code division multiple access (CDMA) is a US
standard
 Short message service (SMS)
 Cell phone standards for Internet access
 Wireless application protocol (WAP)
 Wireless markup language (WML)
 I-mode from Japan
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Standards for B Devices for Wireless
Computer Networks
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Bluetooth (IEEE 802.15) for networks up to 8 devices with a
10-meter area (PANS). Can be used with both A and B
devices.
For LANs the dominant standards are 802.11b and 802.11g
know as Wi-Fi (wireless fidelity)
 Laptops need a wireless network interface card
 Wireless devices communicate with the LAN by
communicating with an access point which is basically a
radio receiver/transmitter. The access point (hotspot) is
connect to a wired network or router
 Wireless devices can also communicate directly with
each other
If the access point connects to the Internet (e.g., through
cable or DSL) then Wi-Fi also provides Internet access
Cards exist for laptops that can enable them to use cellular
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phone services (EV-DO)
Other Ways to Access the Internet
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Limits of Wi-Fi access – limited mobility, security,
interference, or no access point to a broadband connection
WiMax is another family of IEEE standards (802.16)
 Range of 31 miles compared to Wi-Fi’s 300 feet
 Data transfer rate of 75 Mbps compared to 54 Mbps for
Wi-Fi
 Very good security and will support voice and video
 Businesses/homes can install rooftop antennas to
receive
 Laptops require a special card; users can work in
vehicles
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Wireless Applications
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Radio frequency identification (RFID)
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Wireless Sensor Networks (not covered)
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Radio Frequency ID (RFID)
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RFID tags consist of a microprocessor and an antenna.
Some tags can transmit on their own; others transmit
through activation by a reader sending a signal to the
chip
History
 Technology was invented in 1934
 Many different kinds of tags with many different
capabilities such as range, storage capacity,
alterability of data
RFID tag of primary interest are the EPC (electronic
product code) chips
 Designed to replace UPC codes
 96-bit storage capacity; potential to give individual
items a unique identifier; operate in 868-965 MHz
 Signals can only be read if within a few feet of reader
 Cost of tags is still high 5-10 cents per tag; limited to
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large ticket items
RFID Tags (Continued)
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Major applications of EPC chips (current and
future)
 Track and locate inventory
 Track items as they move through a firm’s
supply chain
 Smart shelves
Privacy issues (EPC tags)
 Notification of the presence of a tag
 Killing the tag before you leave the store
 Restrictions on the use of tag generated
data
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Current Uses of RFID
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Future Uses of RFID
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