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Chapter 10. Wireless Ethernet

Chapter 10. Wireless Ethernet

IEEE 802.11 Standards, also known as wireless Ethernet, have been developed mainly for enterprise LAN applications. However, the convenience of wireless connections and the affordability of transceiver technologies make it an attractive option for home networking. A wireless Ethernet can be initiated by installing an 802.11 hub, which is linked to a backbone wired network such as a conventional Ethernet, an ADSL, or a cable modem–based broadband access network, in an office or a home environment. Wireless Ethernet NICs also need to be installed inside other computing or communication devices to share these wireless connections. A laptop PC equipped with a wireless Ethernet NIC can enjoy wireless connectivities at home, office, or even some public area such as an airport or a hotel with 802.11 hubs.

Initial versions of RF wireless Ethernet are based on spread spectrum technologies. Spread spectrum technology was originally developed during World War II for secret RF communication applications. A spread spectrum communication system can be implemented using either frequency hopping or direct sequence technologies. For the Frequency-Hopping Spread Spectrum (FHSS) technology, the carrier hops on a set of frequencies in a particular sequence. For the Direct Sequence Spread Spectrum (DSSS) technology, the energy of a signal is spread to a broader bandwidth by a particular higher rate time domain sequence. These frequency hopping or time domain sequences are known only by the intended partners to maintain communications secrecy. On the other hand, the use of spread spectrum technology can also provide a Signal-to-Noise Ratio enhancement in a nonregulated RF environment. For SNR enhancement, both FHSS and DSSS technologies have been attempted for wireless LAN applications before the finalization of the IEEE 802.11 standards.


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