Transcript Extended Learning Module C

Chapter 6 Business Networks and
Telecommunications
Ch 6 Oz (5th ed)
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Telecommunications and Networks
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Telecommunications concerns the movement of
information between two devices over a distance
 Information includes data, audio, or video
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Networks are collections of devices (nodes) that can
engage in telecommunications
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The Value of Telecommunications in
Business
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Telecommunications has improved business
efficiency and effectiveness to the point that
business cannot be conducted without
telecommunications
Advantages
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Better business communication
Geographical distance irrelevant
Faster communication/instant transaction
Information becomes immediately available
Better distribution of data
Flexible and mobile workforce
Alternative channels
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Dominant Telecommunications
Applications
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Cell phones (local and long distance calls, GPS,
email, digital cameras)
Video conferencing
Fax
Banking (ATMs and online)
RFID in warehouse and wireless payments (gas
pump)
Peer-to-peer file sharing (Napster)
Web-empowered commerce
 Buying and selling
 Training and education
 Research
 Marketing
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The Current Business Environment for
Large Firms
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The network infrastructure for a large corporation
consists of three separate telecommunications
systems
 Data (text, numbers, etc.)
 voice,
 video images.
The environment is moving towards a common
Internet foundation for all three (converged
networks)
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Corporate Networks
Voice
Data
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Pieces in the Corporate Network
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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 (data)
Support for a mobile sales force) (voice)
Separate telephone network (cell and landline)
(voice)
Separate video conferencing system (not shown)
(video)
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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Digital and Analog Signals
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Digital signals (1’s and 0’s) are represented by a
discrete non-continuous wave form.
Analog signals are represented by a sine curve . The
human voice, music, and noise are examples of
analog signals
From a physical point of view, signals can be
converted to an electric (carried over a wire) or
electromagnetic (radio) signal
In telecommunications there is a need to convert
digital signals to analog signals and vice versa.
Computers emit digital signals but parts of the
telephone system only transmit analog signals, so
digital signals 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.
Broadband (multiple signals) versus baseband (one signal)
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Representation of Signals
Figure 6.8 Signal modulation
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Electromagnetic Frequency Spectrum
(Radio Waves)
ELF
VLF
100
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LF
1K
MF
100K
HF
1M1M
VHF
10M
UHF
100M
Microwave
1G
Optical
Hertz
10G
All waves behave
similarly
Frequency differences
 Amount of data
 Distance
 Interference / Noise
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Electromagnetic Signals
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.
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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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Measures of Transmission Speeds
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Multiplexing Concept
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A channel is a path followed by a flow of information
(stream of bits). The information is carried by a
digital or analog signal.
Channels and bandwidth – cell phone example
Multiplexing uses a single 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
code enabling multiple users on a single channel (CDMA)
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Transmission Media
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Wire mediums
 twisted pair
 coaxial cable
 fiber optic (each strand carries one signal)
 Next generation optical networks (multiple data
streams over a single strand)
Wireless transmissions are based on various types
of electromagnetic waves (radio frequencies)
 terrestrial microwave
 satellite microwave (GEO)
 low-orbit satellites (LEO)
Electrical power line (broadband over power lines –
BPL) – Duke Energy will be doing this soon
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Media Comparisons
Figure 6.7 Characteristics of channel media
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Transmission Speeds of Typical
Mediums
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A Simple Network
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Basic Network Components
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A network consists of two or more connected
computers.
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A network interface card (NIC) is the connection
point between one computer and the network
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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. The switch is
used within a given network to move information.
Unlike a switch, a router (or 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.
Modems are used to convert digital signals to analog
signals and vice versa
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Types of Networks
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Geographic scope
 LANs (wired and wireless)
 MANs
 WANs and VANs
 PANs (special type of LAN)
 VPN (virtual private networks)
Role of server
 Client-server networks
 Peer-to-peer networks
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Local Networks: LANs
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Local area network - a network that requires its
own cabling and encompasses a limited distance
(one or two buildings); nodes are usually PCs
and peripherals
Advantages
 handle high volumes of data
 sharing of hardware, software, files, and data
 unique application (email, video conferencing,
on-line applications)
Disadvantages
 expandability
 vendor support or internal expertise
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Wireless LANS
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Benefits
 Easier installation
 Lower initial cost; lower operational costs
 Easily expanded (scalability)
Main drawback is security
 Compared to wired networks wireless networks
are less secure
 Security measures exist but are not as easy to set
up as in wired; tend to slow down transmission
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Large Networks: WAN
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Wide area networks nodes
Corporations can build their own using
communications service providers
Switched and dedicated lines
Individual firm assumes significant role in
telecommunications management
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Large Networks: VANs
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Value-added networks are private data-only
networks that provide economies in service cost and
network management because they are used by
many firms. Many also provide Internet access.
Value-added means customers do not have to invest
in network equipment and management
Disadvantage
 loss of control/expertise
 Security
Tymnet, SprintNet, and General Electric provide VAN
services
An example of a Web based EDI product
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Other Networks
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Metropolitan area network (MAN) links multiple LANs
within a large city
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Personal area network (PAN) wireless network
designed for handheld and portable devices
 Used by one or two people
 Transmission speed slower
 Maximum distance 10 meters
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A virtual private network (VPN) enables companies
to link their LANS to the Internet and protect the LAN
from unwanted intruders. Used in the construction
of intranets and extranets
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Client/Server and Peer-to-Peer Networks
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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
Peer-to-peer networks there is no central device that
controls communication (Napster)
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Switching Techniques
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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 reassembled once they reach their
destinations.
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More efficient use of the network’s capacity
Packets include addressing information and ways to check
transmission errors along with the data.
Always done on the Internet, but restricted to data now
being used for voice (VoIP)
Circuit switching creates a dedicated path between
points in a network. For the duration of the
communication no other transmissions may use this
circuit and all transmissions follow a dedicated path.
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The telephone system links together media segments to
create a single unbroken circuit for each telephone call.
Not very efficient for large volumes of data
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Protocols
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Protocols are rules and procedures (virtually
languages) that govern the transmissions
between components (devices) in a single
network or between two networks
Important protocols
 TCP/IP (Internet protocols)
 HTTP (Internet protocol)
 Ethernet is the most popular protocol for wired
LANs
Important wireless protocols
 Wi-Fi
 Bluetooth
 WiMax
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TCP/IP
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TCP/IP is the communications protocol used by the
Internet and all Internet devices.
TCP 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 part
 Responsible for the delivery of packets
 Includes the disassembling and reassembling of
packets during transmission
 Defines the numeric addressing scheme; 4 bytes
in length; 232 potential addresses
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More on TCP/IP
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Adoption by the world of TCP/IP as a standard
protocol is a major factor in the success of the
Internet
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Other terms associated with the Internet and TCP/IP
 Host and backbone
 IP number (static and dynamic)
 Domain Name System (DNS)
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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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Wireless Network Protocols
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Wireless technologies are of interest to business
because they eliminate the need for expensive
cables and enable mobility
Wireless protocols (or Wi-Fi) apply to mobile
devices (e.g., laptops or PDA)
 Family of standards IEEE 802.11 (the 11 stands
for the max bit rate supported, 11 Mpbs)
 Most popular is 802.11g which operates in the
2.4-2.5 GHz range
 Transmission range is about 300 ft (distance is
likely to increase)
 To make a device wireless requires the device
to contain a wireless card
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Access Points and Hot Spots
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In order to communicate with a network using a
wireless device, you must be close enough to an
access point (AP). The access point is a device
that is connected to a wired network.
 If a household has a wired connection to the
Internet (cable or DSL) then wireless devices
can access the Internet by acquiring a wireless
router (an AP) that is connected to your cable
or DSL modem. This enables all your wireless
devices to link to the Internet.
 Public access points are often called hotspots.
Winthrop has several hotspots on campus
 Cell phones with dual circuitry can
communicate with hot spots
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Wireless Issues
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Plus side
 Mobility and low installation cost
 Can be extended by adding access points
 Newer protocols in the 802.11 family offer
security protocols (WEP, WPA, and WPA2)
Down side
 Interference from other devices
 The Wi-Fi standard (802.11g is replacing
802.11b) is easily penetrated by outsiders with
appropriate hardware and software
 Competing standards (protocols); Bluetooth is
another wireless networking standard for
creating small private networks (range of 30
meters)
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Wireless Applications
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Use of wireless devices in warehouses
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Airlines are equipping their planes with Wi-Fi
circuitry so passengers can connect to the Internet
in flight
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Utility companies have installed meters that can
send signals to the utility company indicating
customer usage
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Equipping electronic devices such as cell phones,
digital cameras, game consoles, digital camcorders
with Wi-Fi circuitry eliminates need for a physical
connection.
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WiMAX Protocol
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WiMAX (IEEE 802.16)
 Increases range and speed of Wi-Fi to 8-10 miles
and 100 Mbps
 Enables an entire city to become a hotspot
 Provide low-cost Internet service to masses
 No need for telephone companies
 A nationwide network could be built for less than
$3 billion
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How Wi-MAX Works
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Mobile Broadband Wireless Access
(MBWA or IEEE 802.20)
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This protocol will enable cell phones to use cell phone towers
to get VoIP and access Internet resources
Similarly a laptop with a special MBWA card will be able to act
as a cell phone
A device that employs this protocol will be able to do
everything you currently do with a telephone through the
Internet (Web browsing, file transfer, e-mail, VoIP video
telephony, videoconferencing, audio streaming, Web –based
gaming, and file sharing).
Protocol will be compatible with Wi-fi and Bluetooth protocols
Protocol will have high levels of security
An example from Sprint
(http://www.sprint.com/business/products/phones/usbU720_all
PcsPhones.html )
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Protocol Summary
Protocol
Usage
Frequency
Range
Wide variety
Speed
TCP/IP
Internet
Wide variety
Ethernet
Wired LANs
IEEE 802.11b and g
(Wi-Fi)
Wireless LANs
2.4-2.5 GHz
Up to 54 Mbps
Bluetooth (IEEE
802.15)
Wireless PANs
2.4-2.5 GHz
1 Mbps
Wi-Max (IEEE
802.16)
Wireless MANs
2-11 GHz
Up to 100 Mbps
CDMA and GSM
Cell phones
Up to 3 GHz
Up to 144 Kbps
MBWA (IEEE
802.20)
Mobile broadband
wireless access
< 3.5 GHz
4 Mbps
EV-DO
Mobile broadband
Internet access
over a cellular
network
Up to 10 Gbps
2.4 Mbps
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Generations of Mobile Communication
(cell phones)
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First generation (1 G)
 Analog signals with circuit switching
Second generation (2 G)
 Use of multiplexing
 Converted voice to digital signals
 Faster than 1 G
Third generation (2.5 G)
 Speeds up to 144Kbps
 Limited Internet access
 Packet switching
Fourth generation (3G)
 Speeds up to 1 Mbps
 Support for video conferencing
 Full Internet access
 Similar to Wi-Fi but more expensive; Wi-Fi inside – 3G outside
Fifth generation (4G)
 Speeds up to 100 Mbps
 Multitasking (listen to music; access Internet; and make calls)
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Internet Networking Services
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Variety of options to choose from when subscribing
to network services
Downstream: speed of receiving from network
Upstream: speed of transmitting to network
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Internet Networking Services (continued)
Figure 6.6: Wireless networking protocols
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Internet Networking Services: Cable and
Digital Subscriber Lines (DSL)
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Cable
 Internet links provided by television cable firms
 At residence, cable split into TV set and
computer; cable modem
 Cable line into a neighborhood is shared by all
subscribers
DSL
 Data remains digital through entire transmission
 Uses telephone lines connected to DSL bridge
 Asymmetric versus symmetric DSL
 Transmission rates related to distance from
telephone company
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Internet Networking Services: T1 and T3 Lines
and Satellite
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T1 and T3 lines
 Point-to-point dedicated digital circuits
 T3 lines made of 24 channels of 64 Kbps
 T1 line made of 672 channels of 64 Kbps
 Expensive; not for individual consumers
Satellite (useful in areas that lack DSL or cable)
 Service use microwaves
 Service provider installs dish antenna, used as
communications satellite
 Speeds up to 45 Mbps
 GPS free satellite service
 Uses fixed or mobile antennas
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Internet Networking Services: Fixed Wireless
and Optical Carrier
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Fixed wireless
 Point-to-point transmission between two stationary devices;
requires microwave transceivers on rooftop
 Wireless Internet service provider (WISP)
 Highly modular and scalable
Optical Carrier (OC)
 Expensive but high connection speeds
 Uses basic unit of 51.84 Mbps
 Used by ISPs, search engines, and content-rich Web sites
Broadband over Power Lines (BPL)
 Uses electric power lines to carry digital signals
 Even if subscriber revenue is low there are advantages to
utility companies; monitor power consumption, detect
power failure, track power outages
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Future of Networking Technologies
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Broadband telephoning
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Radio Frequency Identification
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Convergence of technologies
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Voice over Internet Protocol (VoIP)
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Uses Internet connection to conduct telephone
conversations
Can be done with special software or pay firms that
specialize in the service (Vonnage)
Possible ways to VoIP (PC to PC, PC-to-telephone, or
telephone-to-telephone)
For business users there are significant savings
For individual consumer
 Often you don’t have 911
 No phone when power is out since VoIP requires
an electric modem
Future is with advanced cell phones that support
VoIP; big reduction in cell phone costs
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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
large ticket items
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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
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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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Convergence of Technologies
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Convergence implies one device or one network
doing multiple tasks
 Cell phones will double as Internet phones using
VoIP
 Television sets will be able to function as regular
TV and connect to the Internet concurrently
 PDAs soon will function as a TV and phone
concurrently
 Portable music players (e.g., IPods) can use Wi-Fi
to communicate with other Wi-Fi devices
 Local radio stations can use WiMax for digital
radio; you will be able to download songs you
have listened to and play them back
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