.Summary Chapter 8 1. Identify advantages and disadvantages of each of the four main types of wireless transmission media. Microwave transmission systems are used for high-volume, long-distance, line-of-sight communication. One advantage is the high volume. A disadvantage is that microwave transmissions are susceptible to environmental interference during severe weather such as heavy rain and snowstorms. Satellite transmission systems make use of communication satellites, and they receive and transmit data via line-of-sight. One advantage is that the enormous footprint—the area of Earth's surface reached by a satellite's transmission—overcomes the limitations of microwave data-relay stations. Like microwaves, satellite transmissions are susceptible to environmental interference during severe weather. Radio transmission systems use radio-wave frequencies to send data directly between transmitters and receivers. An advantage is that radio waves travel easily through normal office walls. A disadvantage is that radio transmissions are susceptible to snooping by anyone who has similar equipment that operates on the same frequency. Infrared light is red light that is not commonly visible to human eyes. Common applications of infrared light are in remote-control units for televisions, VCRs, and DVD and CD players. An advantage of infrared is that it does not penetrate walls and so does not interfere with other devices in adjoining rooms. A disadvantage is that infrared signals can be easily blocked by furniture. 2. Explain how businesses can use technology employed by short-range, medium-range, and long-range networks, respectively. Short-range wireless networks simplify the task of connecting one device to another, eliminating wires and enabling users to move around while they use the devices. In general, short-range wireless networks have a range of 100 feet or less. Short-range wireless networks include Bluetooth, ultra-wideband, and near-field communications. A business application of ultra-wideband is the PLUS Real-Time Location System from Time Domain. Using PLUS, an organization can locate multiple people and assets simultaneously. Medium-range wireless networks include Wireless Fidelity (Wi-Fi) and mesh networks. Wi-Fi provides fast and easy Internet or intranet broadband access from public hotspots located at airports, hotels, Internet cafés, universities, conference centers, offices, and homes. Mesh networks use multiple Wi-Fi access points to create a wide area network that can be quite large. Wide-area wireless networks connect users to the Internet over geographically dispersed territory. They include cellular telephones and wireless broadband. Cellular telephones provide two-way radio communications over a cellular network of base stations with seamless handoffs. Wireless broadband (WiMAX) has a wireless access range of up to 31 miles and a data-transfer rate of up to 75 Mbps. WiMAX can provide long-distance broadband wireless access to rural areas and remote business locations. 3. Provide a specific example of how each of the five major m-commerce applications can benefit a business. Location-based services provide information specific to a location. For example, a mobile user can (1) request the nearest business or service, such as an ATM or restaurant; (2) receive alerts, such as a warning of a traffic jam or an accident; and (3) find a friend. With location-based advertising, marketers can integrate the current locations and preferences of mobile users. They can then send user-specific advertising messages about nearby shops, malls, and restaurants to wireless devices. Mobile financial applications include banking, wireless payments and micropayments, money transfers, wireless wallets, and bill-payment services. The bottom line for mobile financial applications is to make it more convenient for customers to transact business regardless of where they are or what time it is. Intrabusiness applications consist of m-commerce applications that are used within organizations. Companies can use nonvoice mobile services to assist in dispatch functions—that is, to assign jobs to mobile employees, along with detailed information about the job. When it comes to accessing information, mobile portals and voice portals are designed to aggregate and deliver content in a form that will work within the limited space available on mobile devices. These portals provide information anywhere and anytime to users. Telemetry is the wireless transmission and receipt of data gathered from remote sensors. Company technicians can use telemetry to identify maintenance problems in equipment. Car manufacturers use telemetry applications for remote vehicle diagnosis and preventive maintenance. 4. Describe technologies that underlie pervasive computing, providing examples of how businesses can utilize each one. Pervasive computing is invisible and everywhere computing that is embedded in the objects around us. Two technologies provide the infrastructure for pervasive computing: radio-frequency identification (RFID) and wireless sensor networks (WSNs). RFID is the term for technologies that use radio waves to automatically identify the location of individual items equipped with tags that contain embedded microchips. WSNs are networks of interconnected, battery-powered, wireless devices placed in the physical environment to collect data from many points over an extended space. 5. Explain how the four major threats to wireless networks can damage a business. The four major threats to wireless networks are rogue access points, war driving, eavesdropping, and radio-frequency jamming. A rogue access point is an unauthorized access point to a wireless network. War driving is the act of locating WLANs while driving around a city or elsewhere. Eavesdropping refers to efforts by unauthorized users to access data that are traveling over wireless networks. Radio-frequency jamming occurs when a person or a device intentionally or unintentionally interferes with wireless network transmissions.