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To access the contents, click the chapter and section titles.
Wireless Networking Handbook
IEEE 802.3 describes several physical layer specifications, namely 10baseT and 100baseT. The word base identifies the use of baseband signalsthat is, digital signals. The 10 and 100 mean 10 Mbps and 100 Mbps, respectively. 10baseT and 100baseT configure network devices as shown in figure 8.7. Both enable computers to connect in a star topology, via IEEE 802.3 network interface cards (ethernet boards), to a hub or switch at a distance of 100 meters (300 feet). A hub normally deploys shared ethernet that constitutes a single-collision domain. As an example, when station A transmits a frame, all other stations connected to that hub (B and C) will receive it. Since ethernet operates in a half-duplex mode, station A will block all other stations connected to the hub (within the collision domain) from transmitting. A switch, though, is smarter because it physically connects the sending station directly to the receiving station only. This results in multiple collision domains that significantly increase throughput. For example, communications can take place simultaneously between stations A and H and stations D and G.
Interbuilding ConnectionsThe interconnection of buildings often goes beyond the range of wireless LAN technologies and standards. Therefore, you need to use other means to provide these types of connections. In general, the wireless technologies offer many advantages as noted in Chapter 1, Introduction to Wireless Networking, for installation of links between buildings in difficult-to-wire environments, such as across freeways, rivers, or hard soil. For wireless implementations, consider the use of radio-based or infrared-based approaches as described in Chapter 3, Wireless Metropolitan Area Networks (MANs). Recall that these methods use highly directive signals to focus the power in a single direction. Choosing Interbuilding MediaThe following are some suggestions for choosing a wireless interbuilding medium type: Radio Waves Consider the use of radio waves for the following situations:
Infrared Light Consider the use of infrared light for the following situations:
Optical Fiber Optical fiber is an alternative to wireless networking. In many cases, your local city, county, or building company might have installed multiple optical fiber strands between buildings in your area. In that case, building-to-building interconnectivity would only require you to obtain access to the fiber in both of the buildings. But if no fiber exists between the buildings of interest, a wireless solution will probably be most practical. Wide Area NetworksIf requirements indicate the need for mobile users covering a large geographical area to have access to network resources, then you certainly want to focus on one of the wireless WAN approaches mentioned in Chapter 4, Wireless Wide Area Networking (WANs). These approachespacket radio, analog cellular, CDPD, satellite, or meteor burstare all based on the use of radio waves. Refer to Chapter 4 for trade-offs between these wireless methods when selecting a wireless WAN technology. In many cases, though, you may be only deploying wireless LAN components. Requirements stating the need for high bandwidth and operation from fixed sites will necessitate the design and implementation of a wire-based WAN. The remaining part of this section briefly describes traditional WAN concepts and technologies.
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