These systems however are more complex to design and

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Unformatted text preview: Ls) technology has been designed to support fixed wireless systems. Since WLLs provide fixed wireless access (as opposed to mobile access provided by cellular and PCS), they can provide several MHz of bandwidth that can be used for high-speed Internet access and data transfer in addition to the basic telephone service. These loops allow long-distance carriers to bypass the existing wired local loops owned b) local telephone carriers (which may result in the saving of tremendous access charges). Due to this reason, man} long-distance companies in advanced countries (like the U.S.) are looking to build their WLLs to avoid paying access charges. Moreover, in developing nations where laying thousands of miles of copper cable is impractical WLLs can be used to provide telephone and low-speed data transfer services. Among many choices of technologies that can be used in WLL environments, cellular and microcellular system; can be used in the 900, 1800, and 1900 MHz ranges with 9.6 Kbps for 10 to 100 users within a few kilometer; range. Wireless LANs can be deployed to support WLL for users in smaller areas but with higher bandwidth requirements. Systems that are especially designed for fixed wireless access, such as Local Multipoint Distribution Systems (LMDS), can provide very high bandwidth (tens of Mbps) in large areas for large number o users but require a direct line of sight. Radio-router Technology Radio-router technology is an emerging wireless technology designed to make links in an IP network mobile. It uses a radio-transmission framework for packetbased, broadband, IP wireless communications. A radio-router network can be built on top of the existing IP infrastructure, rather than from the ground up like a 3G network Since IP network technology is already well developed and inexpensive, radio-router systems will be relatively easy, quick, and economical to implement. The technology uses OFDM (Orthogonal Frequency Division Multiplexing), in which a single channel is divided i...
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