Title: Chapter 6 Business Networks and Telecommunications
1Chapter 6 Business Networks andTelecommunications
2Telecommunications 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
3The 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
4Dominant 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
5The 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)
6Corporate Networks
Voice
Data
7Pieces 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?
8Digital and Analog Signals
- Digital signals (1s and 0s) 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) -
9More 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)
10Representation of Signals
11Electromagnetic Frequency Spectrum(Radio Waves)
TV 54M - 216 MHz
TV 220M - 500 MHz
AM 550K - 1650 KHz
FM 88M - 108 MHz
Navy/submarines
ELF
VLF
LF
MF
HF
VHF
UHF
Microwave
Optical
Hertz
100
1K
100K
1M1M
10M
100M
1G
10G
- All waves behave similarly
- Frequency differences
- Amount of data
- Distance
- Interference / Noise
Public Safety 150M - 160 MHz
Public Safety 460M - 500 MHz
Cellular phones 800 MHz
Cordless phones (some) 900 MHz
PCS ET 2 GHz
Pers. Com. Sys (PCS) 1.85 G - 2.2 GHz
12Electromagnetic 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. -
13Transmission 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 Nyquists theorem - C2f(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
14Measures of Transmission Speeds
15Multiplexing 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)
16Transmission 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
17Media Comparisons
18Transmission Speeds of Typical Mediums
19A Simple Network
20Basic 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)
21Basic 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
22Types 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
23Local 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
24Wireless 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
25Large 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
26Large 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
27Other 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
28Client/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)
29Switching 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 networks 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
30Protocols
- 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
31TCP/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
32More 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)
33Internet 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 21022103103103221094 (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
34Wireless 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
35Access 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
36Wireless 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)
37Wireless 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.
38WiMAX 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
39How Wi-MAX Works
40Mobile 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/busi
ness/products/phones/usbU720_allPcsPhones.html )
41Protocol Summary
42Generations 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)
43Internet 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
44Internet Networking Services (continued)
Figure 6.6 Wireless networking protocols
45Internet 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
46Internet 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
47Internet 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
48Future of Networking Technologies
- Broadband telephoning
- Radio Frequency Identification
- Convergence of technologies
49Voice 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 dont 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
50Radio 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
51RFID Tags (Continued)
- Major applications of EPC chips (current and
future) - Track and locate inventory
- Track items as they move through a firms 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
52Current Uses of RFID
53Future Uses of RFID
54Convergence 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