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Chapter 6 Business Networks and Telecommunications

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Title: Chapter 6 Business Networks and Telecommunications


1
Chapter 6 Business Networks andTelecommunications
  • Ch 6 Oz (5th ed)

2
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

3
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

4
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

5
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)

6
Corporate Networks
Voice
Data
7
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?

8
Digital 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)

9
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)

10
Representation of Signals
11
Electromagnetic 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
12
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.

13
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 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

14
Measures of Transmission Speeds
15
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)

16
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

17
Media Comparisons
18
Transmission Speeds of Typical Mediums
19
A Simple Network
20
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)

21
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

22
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

23
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

24
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

25
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

26
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

27
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

28
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)

29
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 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

30
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

31
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

32
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)

33
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 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

34
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

35
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

36
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)

37
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.

38
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

39
How Wi-MAX Works
40
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/busi
    ness/products/phones/usbU720_allPcsPhones.html )

41
Protocol Summary
42
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)

43
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

44
Internet Networking Services (continued)
Figure 6.6 Wireless networking protocols
45
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

46
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

47
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

48
Future of Networking Technologies
  • Broadband telephoning
  • Radio Frequency Identification
  • Convergence of technologies

49
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 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

50
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

51
RFID 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

52
Current Uses of RFID
53
Future Uses of RFID
54
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
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