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Chapter 6 Business Networks and
Telecommunications
Ch 6 Oz (5th ed)
1
Telecommunications and Networks
Telecommunications concerns the movement of
information between two devices over a distance
Information includes data, audio, or video
Networks are collections of devices (nodes) that can
engage in telecommunications
2
The Value of Telecommunications in
Business
Telecommunications has improved business
efficiency and effectiveness to the point that
business cannot be conducted without
telecommunications
Advantages
Better business communication
Geographical distance irrelevant
Faster communication/instant transaction
Information becomes immediately available
Better distribution of data
Flexible and mobile workforce
Alternative channels
3
Dominant Telecommunications
Applications
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
4
The Current Business Environment for
Large Firms
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)
5
Corporate Networks
Voice
Data
6
Pieces in the Corporate Network
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? 7
Digital and Analog Signals
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)
8
More on Signals
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)
9
Representation of Signals
Figure 6.8 Signal modulation
10
Electromagnetic Frequency Spectrum
(Radio Waves)
ELF VLF LF MF HF VHF UHF Microwave Optical
100 1K 100K 1M1M 10M 100M 1G 10G Hertz
All waves behave
similarly
Frequency differences
Amount of data
Distance
Interference / Noise
11
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.
12
Transmission Speeds
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
13
Measures of Transmission Speeds
14
Multiplexing Concept
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
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)
15
Transmission Media
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
16
Media Comparisons
Figure 6.7 Characteristics of channel media
17
Transmission Speeds of Typical
Mediums
18
A Simple Network
19
Basic Network Components
A network consists of two or more connected
computers.
A network interface card (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)
20
Basic Network Components (continued)
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
21
Types of Networks
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
22
Local Networks: LANs
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
23
Wireless LANS
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
24
Large Networks: WAN
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
25
Large Networks: VANs
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
26
Other Networks
Metropolitan area network (MAN) links multiple LANs
within a large city
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
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
27
Client/Server and Peer-to-Peer Networks
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)
28
Switching Techniques
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.
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.
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 29
Protocols
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
30
TCP/IP
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
31
More on TCP/IP
Adoption by the world of TCP/IP as a standard
protocol is a major factor in the success of the
Internet
Other terms associated with the Internet and TCP/IP
Host and backbone
IP number (static and dynamic)
Domain Name System (DNS)
32
Internet Protocol Numbers (IPv4)
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.ip-
adress.com/speedtest/
To determine your IP number: http://www.What ismyIpaddress.com
33
Wireless Network Protocols
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
34
Access Points and Hot Spots
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
35
Wireless Issues
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)
36
Wireless Applications
Use of wireless devices in warehouses
Airlines are equipping their planes with Wi-Fi
circuitry so passengers can connect to the Internet
in flight
Utility companies have installed meters that can
send signals to the utility company indicating
customer usage
Equipping electronic devices such as cell phones,
digital cameras, game consoles, digital camcorders
with Wi-Fi circuitry eliminates need for a physical
connection.
37
WiMAX Protocol
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
38
How Wi-MAX Works
39
Mobile Broadband Wireless Access
(MBWA or IEEE 802.20)
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 ) 40
Protocol Summary
Frequency
Protocol Usage Speed
Range
TCP/IP Internet Wide variety Wide variety
Ethernet Wired LANs Up to 10 Gbps
IEEE 802.11b and g Wireless LANs 2.4-2.5 GHz Up to 54 Mbps
(Wi-Fi)
Bluetooth (IEEE Wireless PANs 2.4-2.5 GHz 1 Mbps
802.15)
Wi-Max (IEEE Wireless MANs 2-11 GHz Up to 100 Mbps
802.16)
CDMA and GSM Cell phones Up to 3 GHz Up to 144 Kbps
MBWA (IEEE Mobile broadband < 3.5 GHz 4 Mbps
802.20) wireless access
EV-DO Mobile broadband 2.4 Mbps
Internet access
over a cellular
network
41
Generations of Mobile Communication
(cell phones)
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)
42
Internet Networking Services
Variety of options to choose from when subscribing
to network services
Downstream: speed of receiving from network
Upstream: speed of transmitting to network
43
Internet Networking Services (continued)
Figure 6.6: Wireless networking protocols
44
Internet Networking Services: Cable and
Digital Subscriber Lines (DSL)
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
45
Internet Networking Services: T1 and T3 Lines
and Satellite
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
46
Internet Networking Services: Fixed Wireless
and Optical Carrier
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
47
Future of Networking Technologies
Broadband telephoning
Radio Frequency Identification
Convergence of technologies
48
Voice over Internet Protocol (VoIP)
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
49
Radio Frequency ID (RFID)
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
50
RFID Tags (Continued)
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
51
Current Uses of RFID
52
Future Uses of RFID
53
Convergence of Technologies
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
54
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