Principles of Information Systems Eighth Edition

1
Principles of Information SystemsEighth Edition

• Chapter 6
• Telecommunications and Networks

2
Principles and Learning Objectives

• ??????????????????????????????????????????????????
  ???????????????
• ????????????????????????? communications ???
  telecommunications ?????????????????????????????
  telecommunications

3
Principles and Learning Objectives (continued)?

• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ???? ???????????????????????????
• ????????????????????????? 2 ??????????????????????
  ??????????
• ??????????????????????????????????????????????????
  ????????????
• ????????????????????????(telecommunications
  carriers) 3 ????
• ???????????????????????????????????(telecommunicat
  ions network)

4
Principles and Learning Objectives (continued)?

• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ???? ???????????????????????????(continued)?
• ?????????????????????? communications protocols
  ????????????????? protocol ???
• ?????? 3 ??????????? distributed processing
• ??????????????????????????????????????????????????
  ???

5
Why Learn About Telecommunications and Networks?

• Need to access data wherever it resides
• Fast, reliable communications
• Exchange messages
• Upload/download data and software
• Route business transactions
• Connect to remote databases
• Send output to printers

6
An Overview Of Telecommunications

• Telecommunications(???????????????????) ???
  ????????????????????????????????????????? ?
  ??????????????????????????????????????????????
• Telephone, radio, and television
• Communications can be synchronous or asynchronous
• Synchronous communications ??????????????????????
  ?????? ???-??? ???????????????????????
• Asynchronous communications ?????????????????????
  ??????? ????????????-??? ???????????????????????

7
An Overview Of Telecommunications (continued)?
Figure 6.1 Elements of a Telecommunications
System
8
Basic Communications Channel Characteristics

• Communication channels(?????????????????) can be
  classified as
• Simplex channel (?????????????????????)
  ??????????????????????????????????????????????????
  ???????????? One-way Communication ????
  ?????????????????????? ????????????????????????
• Half-duplex channel (??????????????????????????)
  ???????????????????????????????????
  ???????????? ?????????????????????????????????
  ???? ??????????????????????? ????????? ??????
  ???????
• Full-duplex channel (???????????????????)
  ??????????????????????????-??? ???????????????????
  ???????? ???? ??????????????

9
Channel Bandwidth

• Channel bandwidth ???????????????????????????????
  ????????? ???????????????????
• ??????????????? bits per second (bps)?
• Broadband communications (???????????????????????
  ?????)
• ?????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ???????????????????? ?????????????????????????????
  ??????????????? ???????????????????????????
• - ??????????????????????????????
  ???????????????????????????????? ? ??????????
• Narrowband communications telecommunications
  system that supports a much lower rate of data
  exchange than broadband

10
Communications Media

• Guided transmission media communications signals
  guided along a solid medium
• Wireless media communications signal broadcast
  over airwaves as a form of electromagnetic
  radiation

11
Guided Transmission Media Types
????????????????? ???????? ????? ???????
?????????????? ????????????????????? ???????????????? ????????????? - ??????????????????????????????? ????????????????????????????????????????????????? ???????????????????????????????????
????????????? ??????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????? ?????????????????????????
????????????????? ???????????????????????????????????????????????????????????????????????????????? ??????????????????????? ?????????????????????????????? ? ?????????? ????????????????? ?????????????????????? ????????????????????????????? ???????????????????????????????? ??????????????????????
Home Plug, Broadband Over Powerlines ?????????????? ?????????????????????????????????????????????????????????????????????????? ?????????????? ???????????, ???????????, ????????????????? ???????????, ???????????????????????????????
12
Guided Transmission Media Types
????????????????? ???????? ????? ???????
???????? ??????????????????????????????????????????????? ??????????????????????????????????? ?????????????????????????????? - ???????????????????????????? - ??????????????????????
?????????? ??????????????? 30-300 MHz ??????????????????????? ?????????? -??????????????????????
????????? ??????????????????????????????????????? ??????????????????????????????? ??????????????????????? ????????????????????????????? - ?????????????????????????
13
Telecommunications Hardware

• Typical telephone line only accommodates an
  analog signal (continuous, curving signal)?
• Computers generate a digital signal representing
  bits
• Modem ????????????????????????????????????????
  ??????????????????????????????????????????????
  ?????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ?????????????????????????????????????

14
Telecommunications Hardware (continued)?
Figure 6.6 How a Modem Works
15
Telecommunications Hardware (continued)?

• Multiplexer ?????????????????????????????????????
  ???? ? ???????????????????????? ?
  ??????????????????????????????????????????????????
  ???????????????????????????????
• Front-end processors ????????????????????????????
  ???????????????
• ?????????????????????????????????????????????????
  ????
• ????????????????????????????????
• ????????????????????????????????
• ????????????????????? ? ???? ?????? ???????
  ???????????????????????? ? ???????????????????????
  ???????

16
Services

• Telecommunications carriers organize
  communications channels, networks, hardware,
  software, people, and business procedures to
  provide valuable communications services

17
Digital Subscriber Line (DSL)?

• Telecommunications technology that delivers
  high-bandwidth information to homes and small
  businesses over ordinary copper telephone wires
• Asymmetric DSL (ADSL) ????????????? download
  ?????? upload
• Symmetric DSL (SDSL) ????????????????????????????
  ???????
• Does not allow you to use the phone at the same
  time

18
Digital Subscriber Line (DSL) (continued)?
Figure 6.8 Digital Subscriber Line (DSL)?
19
Wireless Telecommunications

• All major long-distance carriers offer wireless
  telecommunications services
• Phone calls or Internet access
• Wireless data communications will be broadly
  adopted when providers can offer business users
  enough bandwidth and connectivity so that they
  use wireless as their sole connection

20
Networks and Distributed Processing

• Computer network ????????????????????????????????
  ?????????????????????????????????????????????
  ????????????????????????? ????????????????????????
  ????? ????????????????????????????????????????????
  ? ??? ????????????????????????????????????????????
  ?????????????
• Network nodes ????????????????????????????????com
  puters and devices on the networks

21
Network Types

• Personal area network (PAN) ??????????????????????
  ???????????? ???? Bluetooth , Ultra Wide Band?
  (?????????????????1m)
• Local area network (LAN)? ????????????????????????
  ???? ???????????? ?????????????? ??????????????
• Metropolitan area network (MAN)?
  ????????????????????????? ????
  ??????????????????????????????????
  ??????????????????????????????????????????????????
  ??
• Wide area network (WAN)? ????????????????????????
  ????????? LAN ??????? 2 ????????????????????????
  ????? ????????????????????????????????????????????
  ???????????????????????????????? ??????
  ???????????????????????
• International networks ???????????????????????????
  ????????????????
• Mesh networking ???????????????????????
  ?????????????????? ????????????????????????????
  ?????????????????????????????

22
Network Types (continued)?
Figure 6.11 Partial Mesh Network
23
Distributed Processing

• Centralized Processing ?????????????????????????
  ????????????????????????? (????????????)
  ????????????????????????????????????
  ???????????????????? ????????
• Decentralized processing ??????????????????????
  ????????????????????????????????
  ?????????????????????????? ? ?????????????????????
  ??????????????????????????????
• Distributed processing ?????????????????????????
  ????????????????????????????????????????

24
Client/Server Systems

• Client/server ???????????????????????????????????
  ????????????????????
• ??????????????????????????????????????????????????
  ??????????????????? ????????????(Server)
• ?????????????????????????? ??????????????(Client)

25
Client/Server Systems (continued)?
Figure 6.13 Client/Server Connection
26
Communications Software and Protocols

• Communications protocol ?????????????????
  ????????? ?????? ????????????????????????????
  ??????????????????
• ATM ( Asynchronous Transfer Mode )
• ???????????? Packet Switching (???????????????????
  ???????? ????????????????? packet
  ???????????????? ?????????????????????????????????
  ?????????????????????????????? ???????????????????
  ???????????????????) ???????????????????????????
  10 Gbps
• ???????????????????????????????????
• ?????????????????????????????????????
  ?????????????????? ???????????????????????????????
  ????????????? ????????????
• ???????????????????????????? ?????? ?????? ??????
  ???????? ???????????????????????????????????
  ??????????????????????????????? ??????? LAN ???
  WAN ???????

27
Communications Software and Protocols

• Frame relay
• ????????????????????? Packet Switching
• ??????????????????????????? 2Mbps
• IEEE 802.3 (Ethernet)?
• ???????????????????????? delay ????????????????
  10 ???? ??????????????????????????????? Fast
  Ethernet
• ??????????????????
• T-carrier system
• - ????????????? ? ????????????????????????????
  ??????????
• ????????
• - ?????????????????????????????
• - ????????????????????????????????????????
  ?? ?????????????????
• ??????????????????

28
Wireless Communications Protocols

• Wi-Fi ???????? Wireless Fidelity
  ????????????????????? Wireless LAN ???? WLAN
  ????????????????? ????????? ???
• WiMAX ???????? WiFi ????????????????????????????
  ????????????????????????????????? ????
  ??????????????????????????
• Smart antenna technology ??????????? ?????
  (???????????)
• Ultra Wideband (UWB)? ???????????????????????????
  ???? ???????????? ??????????????????????
  480Mbps ???????? Bluetooth ???????????????????????
  ???????????????, ??????, ???????? ???????
• 3G wireless communication ???????????????????????
  ??????????????????? ??????????????????????????????
    ???????????????? ???
• 4G wireless communications ?????????????????????
  3G ???  ????????????????????????????????????
  20-40 Mbps

29
Wireless Communications Protocols (continued)?
Table 6.14 Wi-Fi Network
30
Wireless Communications Protocols (continued)?

• Switch ????????????????????????????????????????
  ??????????????????????????????????????????????
• Bridge ????????????????????????????????????
  ???? LAN ??? LAN ?????? protocol ????????
• Router ????????????-?????????????????????????????
  ??????????????????? ??????? Router
  ??????????????????????????? Address ???????? ???
  Router ???????????? Address ?????????????????????
  ??????????????????????????????????????????????????
  ?????????????????????????
• Gateway ?????????????????????????????????????????
  ????????????????? ?????????????????????????-?????
  ?????????????????

31
Communications Software

• Network operating system (NOS)
• ??????????????????????????????????????????????????
  ?????????????????????????? ???????????????????????
  ????
• ???????????????????????????????
• ????????? ???? ???????????????????????
  ????????????????????????????????? ???????????
  ??????????????????????????
• ???? Windows NT Windows 2000 Server ???????
• Network-management software
• ??????????????????????????????????????????????????
  ????????????????????
• Scans viruses
• ?????????? software licenses

32
Telecommunications and Network Applications

• Telecommunications and networks are a vital part
  of todays information systems
• In some industries, telecommunications is
  virtually a requirement for doing business

33
Linking Personal Computers to Mainframes and
Networks

• Personal computers can be connected to mainframe
  computers so that data can be downloaded or
  uploaded
• Example user can download a file from a database
  to a personal computer
• Unattended systems ??????????????????????????????
  ??????????????????????????????????????????????????
  ?????????????? ???????????????
  ?????????????????????????????????????????
  ???????????????????????

34
Voice Mail

• Users can send, receive, and store verbal
  messages for and from other people around the
  world
• Call management systems can be linked to
  corporate e-mail and instant messaging systems

35
Home and Small Business Networks

• Simple networks can be used to share printers or
  an Internet connection, access files on different
  machines, etc.
• Wireless network
• 802.11n access point ???? DSL modem
• Combined router, firewall, Ethernet hub, and
  wireless hub
• Configure computers to share printers and files

36
Electronic Document Distribution

• Send and receive documents in a digital form
  without printing them (although printing is
  possible)?
• ?????????????????????????????????
• Much faster
• Saves paper
• Saves document storage space

37
Call Centers

• Call center physical location where an
  organization handles customer and other telephone
  calls
• Usually with some computer automation
• Automatic call distributor (ACD) telephone
  facility that manages incoming calls
• Handles calls based on the called number and an
  associated database of instructions
• National Do Not Call Registry
• Offshore call centers

38
Telecommuting and Virtual Workers and Workgroups

• Telecommuting
• ??????????????, ??????????????????????????????????
  ??????????????????????????????????????????????????
  ???????????????????
• ??????????? ??????? ???????????????
• ????????????????????????????????????????????
  telecommuting ?????? ???? ????????????? ???????

39
Videoconferencing

• ?????????????????????????????????????????
  ??????????????
• ???????????????????????????????
• ??????????????????????????????????????????????????
  ????????????? ??? ???? ??? ????????????????
• ??????????????????????????????????????????????????
  ???? ? ??? ?????????????????????????????????????

40
Electronic Data Interchange(EDI)

• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ??????????????????????????????????????????
• ??????????????????????????????????????????????????
  ????? ???????????????????
• ????????????????????????????? ??????????????
  ????????????? ????? ???????

41
Electronic Data Interchange (continued)?
Table 6.17 Two Approaches to Electronic Data
Interchange
42
Public Network Services

• Give personal computer users access to vast
  databases, the Internet, and other services
• Usually an initial fee plus usage fees
• Fees are based on services used can range from
  under 15 to over 500 per month
• Providers of public network services include
  Microsoft, America Online, and Prodigy

43
Electronic Funds Transfer

• Electronic funds transfer (EFT)?
• Transfers money from one bank account directly to
  another without the use of paper money
• ???? ????????????????????????????????????????????
  ???????????????????????? ?????????????????????????
  ??? ???? ?????????????????????????????????????????
  ? ????????????????????????????????? 7Eleven
• Wire transfer
• Fast, reliable means to move funds from one
  account to another using one of three major
  wire-transfer networks
• Automated clearing house (ACH)?
• Secure private network connecting all U.S.
  financial institutions to each other through the
  Federal Reserve Board or other ACH operators

44
Distance Learning

• ??????????????????????????????????????????????????
  ?????????? ???????????????????????????????????????
  ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ?????????? ???????????????????????????????????????
  ???????????????????????????????????
  ??????????????????????????????????????
• ???????????????????????????????Internet
• ?????????????????????? ????? ????????????????????
  ???????
• ???????????????????? ?????????????????????? web
  board ???? e-mail

45
Team Collaboration Systems

• Microsoft Office Groove example of software
  designed to enable collaboration and
  communication within small teams
• Allows you to set up shared workspaces among
  employees and others outside your organization

46
Specialized Systems and Services

• Increased interest in specialized and regional
  information services
• Electronic bulletin board message center that
  displays messages in electronic form
  ??????????????????????????????????????????????????
  ?? ??????????????????????????????????? ???????
• Regional, national, and international bulletin
  boards
• Global positioning systems (GPSs) provide
  specialized telecommunications services
• Virtual workers conduct business at any time and
  place

47
Summary

• Telecommunications electronic transmission of
  signals for communications, by such means as
  telephone, radio, and television
• Guided transmission media types twisted-pair
  wire, coaxial cable, fiber-optic cable, and
  broadband over power lines
• Wireless transmission types microwave, radio,
  and infrared
• Computer network communications media, devices,
  and software needed to connect two or more
  computer systems and/or devices

48
Summary (continued)?

• Network types personal area network (PAN), local
  area network (LAN), metropolitan area network
  (MAN), wide area network (WAN), international
  networks, and mesh networking
• Client/server systems multiple computer
  platforms dedicated to special functions such as
  database management, printing, communications,
  and program execution
• Communications protocol set of rules that
  governs the exchange of information over a
  communications channel

49
Summary (continued)?

• Examples of telecommunications and network
  applications
• Linking personal computers to mainframes and
  networks, voice mail, home and small business
  networks, electronic document distribution, call
  centers, telecommuting, videoconferencing,
  electronic data interchange, public network
  services, electronic funds transfer, distance
  learning, and team collaboration systems