Chapter 6 Telecommunications, Networks, and Wireless. Computing

Transcription

1 Chapter 6 Telecommunications, Networks, and Wireless Computing Essay Questions: 1. Define a hub, switch, and a router. 2. List the challenges associated with managing contemporary telecommunications and networking technology. 3. What is an information appliance? Identify three client platforms. 4. What are the principle methods for locating information on the Web. Provide an example of each. 5. Identify and briefly explain the four-layered Department of Defense reference model for TCP/IP. 6. How does packet switching work? 7. Define the following terms: ATM, ISDN, DSL, and T1. 8. List five advantages associated with using voice over IP (VoIP) technology. 9. Compare the uses of and groupware. 10. What is the difference between a virtual private network (VPN), an extranet, and an intranet? 98

2 Answers of Essay Questions: 1. Define a hub, switch, and a router. Hubs are very simple devices that connect network components, sending a packet of data to all other connected devices. A switch has more intelligence than a hub and can filter and forward data to a specified destination. Switches are used within individual networks. To communicate with another network, the network would use a device called a router. A router is a special communications processor used to route packets of data through different networks, ensuring that the message sent gets to the correct address. 2. List the challenges associated with managing contemporary telecommunications and networking technology. loss of management control, organizational change requirements, and scalability, reliability, security. 3. What is an information appliance? Identify three client platforms. An information appliance is a device customized to perform specialized computing tasks well with minimal user effort. Client platforms could be identified as - PC, Internet-enabled cell phones,, small handheld devices such as PDAs and wireless handhelds, and TV Internet receiver. 4. What are the principle methods for locating information on the Web. Provide an example of each. The principle methods are Web site directories, search engines, intelligent agents, and push technology. Yahoo! is an example of a Web site directory; Google is an example of a search engine; MySimon is an example of a shopping bot (a type of intelligent software agent). LATimes.com s NewsDirect is an example of push technology. 5. Identify and briefly explain the four-layered Department of Defense reference model for TCP/IP. a) Application layer enables client application programs to access the other layers and defines the protocols that applications use to exchange data. One of these application protocols is the Hypertext Transfer Protocol (HTTP) that is used to transfer Web page files. b) Transport layer responsible for providing the application layer with communication and packet services. This layer includes TCP and other protocols. c) Internet layer responsible for addressing, routing, and packaging data packets called IP datagrams. The Internet Protocol (IP) is one of the protocols used in this layer. d) Network interface layer responsible for placing packets on and receiving them from the network medium, which could be any networking technology. 6. How does packet switching work? Packet switching is a basic switching technique that can be used to achieve economies and higher speeds in long-distance transmission. VANs and the Internet use packet switching. Packet switching breaks up a lengthy block of text into small, fixed bundles of data called packets. There are many different packet sizes, some of them variable, depending on the communications standard being used. (The X.25 standard uses packets of 128 bytes each.) 99

3 The packets include information for directing the packets to the right address, and for checking transmission errors, along with the data. Data are gathered from many users, divided into small packets, and transmitted via various available communications channels. Each packet travels independently through the network. Packets of data originating at one source can be routed to different paths in the network before being reassembled into the original message when they reach their destination. 7. Define the following terms: ATM, ISDN, DSL, and T1. a) ATM-Asynchronous Transfer Mode, parcels information into uniform 53-byte cells, eliminating the need for protocol conversion. It can pass data between computers from different vendors and permits data to be transmitted at any speed the network handles. b) ISDN-Integrated Services Digital Network, an international standard for dial-up network access that integrates voice, data, image, and video services in a single link. c) DSL-Digital Subscriber Line, operates over existing copper telephone lines to carry voice, data, and video, but has higher transmission capacities than ISDN. d) T1-a dedicated telephone connection comprising 24 channels that can support a data transmission rate of Mbps. Each of the 64-Kb-per-second channels can be configured to carry voice or data traffic. These services are often used for high-capacity Internet connections. 8. List five advantages associated with using voice over IP (VoIP) technology. a) Uses the Internet Protocol to deliver voice information in digital form using packet switching, avoiding the tolls charged by local and long-distance telephone networks. b) IP telephone calls can be made and received with a desktop computer equipped with a microphone and speakers or with a VoIP-enabled telephone. c) Can reduce communication and network management costs by 20 to 30 percent. d) Supports Internet conference calls using video e) Flexibility - phones can be added or moved to different offices without rewiring or reconfiguring the network. f) Can be used for telephone voice transmission over the Internet or private networks. 9. Compare the uses of and groupware. allows swift, inexpensive transmission of text messages and attachments to one person or to a list of persons. can go back and forth amongst the members of an organization much more quickly than written materials and hard copy. Groupware provides additional capabilities for supporting enterprise-wide communications and collaborative work. Individuals, teams, and workgroups at different locations in the organization can use groupware to participate in discussion forums and work on shared documents and projects. 10. What is the difference between a virtual private network (VPN), an extranet, and an intranet? A virtual private network (VPN) is a private network of computers linked using a secure tunnel connection over a public network such as the Internet. An intranet is an internal company network based on Internet and World Wide Web technology and standards that is not open to outsiders. An extranet is a private intranet that is accessible to authorized outsiders. 100

4 Chapter 6-2 The Internet: Information Technology Infrastructure for the Digital Firm Essay Questions: 1. Identify at least five principal wireless transmission media and devices. 2. Identify the two major cellular standards and briefly describe the evolution of these networks. 3. What is the difference between Bluetooth and Wi-Fi b wireless technology? 4. What is the difference between Bluetooth and WiMax wireless technology? 5. Evaluate the role of m-commerce in business. Identify some key areas where m-commerce is useful. 6. Explain the difference between wireless mobile portal, voice portals, and m-wallets. 7. Describe how wireless technology can increase productivity and worker output. 8. Describe three important wireless applications in business. Give examples. 9. Describe the main differences between a voice portal and a smart phone. 10. Discuss how wireless transmission works to send signals. 101

5 Answers of Essay Questions: 1. Identify at least five principal wireless transmission media and devices. Technologies and devices for wireless transmission include: microwave transmission, communication satellites, pagers, handhelds, personal digital assistants (PDAs), cellular telephones, and smart phones. Personal computers are also starting to be used in wireless transmission. 2. Identify the two major cellular standards and briefly describe the evolution of these networks. The two major cellular standards include Code Division Multiple Access (CDMA), which is used primarily in the United States, and Global System for Mobile Communication (GSM), which is the standard in Europe and much of the rest of the world. Cellular networks have evolved from slow-speed (1G) analog networks to high-speed high-bandwidth digital packet-switched third-generation (3G) networks with speeds ranging from 144 Kbps to over 2 Mbps for data transmission. Second-generation (2G) cellular networks are digital circuit-switched networks used primarily for voice transmission, but they can also transmit data at rates ranging from 9.6 to 14.4 Kbps. 2.5G networks are packet-switched, use many existing infrastructure elements, and have data transmission rates ranging from 50 to 144 Kbps. 3. What is the difference between Bluetooth and Wi-Fi b wireless technology? Bluetooth can link up to eight devices within a 10-meter area using low-power, radio-based communication and can transmit up to 722 Kpbs in the 2.4 GHz band. Wireless phones, keyboards, computers, printers, and PDAs using Bluetooth can communicate with each other and even operate each other without direct user intervention. The most popular standard of the standards is currently b, which can transmit up to 11 Mbps in the unlicensed 2.4 GHZ band and has an effective distance of 30 to 50 meters, although this range can be extended outdoors by using tower-mounted antennas. The b standard has been the most widely used standard for creating wireless LANs and providing broadband wireless Internet access. However, b is vulnerable to penetration by outsiders and interference from other wireless devices in the same frequency spectrum. 4. What is the difference between Bluetooth and WiMax wireless technology? Bluetooth can link up to eight devices within a 10-meter area using low-power, radio-based communication and can transmit up to 722 Kpbs in the 2.4 GHz band. Wireless phones, keyboards, computers, printers, and PDAs using Bluetooth can communicate with each other and even operate each other without direct user intervention. WiMax has a wireless access range of up to 31 miles and a data transfer rate of up to 75 Mbps, making it suitable for providing broadband Internet access in areas lacking DSL and cable lines. The specifications also have robust security and quality of service 102

6 features to support voice and video. 5. Evaluate the role of m-commerce in business. Identify some key areas where m-commerce is useful. M-commerce uses the Internet for purchasing goods and services as well as for transmitting messages using wireless mobile devices. It is especially well-suited for location-based applications, such as finding local hotels and restaurants, monitoring local traffic and weather, and providing personalized location-based marketing. Mobile phones and handhelds are being used for mobile bill payment, banking, securities trading, transportation schedule updates, and digital music and game downloads. 6. Explain the difference between wireless mobile portal, voice portals, and m-wallets. Wireless portals (mobile portals) feature content and services optimized for mobile devices to steer users to the information they are most likely to need. Voice portals accept voice commands for accessing Web content, , and other electronic applications from a cell phone or standard telephone. M-commerce requires special digital payment systems that can handle micropayments, because most m-commerce purchases today are for very small amounts. Mobile wallets (m-wallets) expedite purchases by storing online shoppers personal information and credit card numbers. 7. Describe how wireless technology can increase productivity and worker output. Wireless technology increases productivity and worker output by providing anytime, anywhere communication and access to information, including the information resources of the Internet. Wireless communication helps businesses stay more easily in touch with customers, suppliers, and employees and provides more flexible arrangements for organizing work. Employees can make productive use of formerly wasted slices of time between larger tasks. 8. Describe three important wireless applications in business. Give examples. Mobile applications are having a significant impact on customer relationship management (CRM), supply chain management (CRM), and health care. a) Mobile CRM applications provide additional support for sales and service activities at the point of customer interaction. b) Mobile wireless technology facilitates supply chain management by capturing data on the movement of goods as these events take place and by providing detailed, immediate information as goods move along supply chain partners. Radio frequency identification (RFID) systems provide a powerful technology for this purpose. c) Mobile technology is improving health care by delivering essential information to physicians and nurses who constantly move from place to place and capturing patient information for electronic record systems at the point of creation. 9. Describe the main differences between a voice portal and a smart phone. A voice portal is a Web site or other service that a user can reach by telephone. For 103

7 example, a voice portal accepts voice commands for accessing Web content, , and other electronic applications from a cell phone or standard telephone. Mobile user with a cellular telephone can dial in to a voice portal Web site and request information from a special voice-producing program at the Web site. This sophisticated voice recognition software processes the requests, and responses are translated back into speech for the customer. Whereas a user with a smart phone can connect to the Internet and get information on a small visual display, the user of a voice portal needs only a regular cellular phone. After requesting information by speaking or pressing keys, the voice portal responds with voice information or, in some cases, with an message. A smart phone can handle voice transmission and ; save addresses; store schedules; access a private corporate network; and access information from the Internet. Some have embedded digital cameras. 10. Discuss how wireless transmission works to send signals. Wireless transmission sends signals through the air or space without being tied to a physical line. All wireless media rely on various parts of the electromagnetic spectrum. Some types of wireless transmission, such as microwave or infrared by nature occupy specific spectrum frequency ranges (measured in megahertz (MHz). Other types of wireless transmissions, such as cellular telephones and paging devices, have been assigned a specific range of frequencies by national regulatory agencies and international agreements. Each frequency range has characteristics that have helped determine the specific function or data communications niche assigned to it. Microwave systems, both terrestrial and celestial, transmit high-frequency radio signals through the atmosphere and are widely used for high-volume, long-distance, point-to-point communication. Microwave signals follow a straight line and do not bend with the curvature of the earth, therefore, long-distance terrestrial transmission systems require that transmission stations be positioned about 37 miles apart, adding to the expense of microwave. 104