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Linux+ Guide to Linux Certification, Second Edition Wireless# Guide to Wireless Communications Wireless# Guide to Wireless Communications Chapter 9 Wireless Metropolitan Area Networks Objectives Explain why wireless metropolitan area networks (WMANs) are needed Describe the components and modes of operation of a WMAN List the range of WMAN technologies, including FSO, LMDS, MMDS, and 802.16 (WiMAX) Explain how WMANs function Outline the security features of WMANs What is a WMAN? Wireless metropolitan area networks (WMANs) Provide wireless connectivity across a substantial geographical area such as a large city WMANs primary goals Extend wired networks beyond a single location Without the expense of high-speed cable-based connections Extend user mobility throughout a metropolitan area Provide high-speed connections to areas not serviced by any other method of connectivity Last Mile Wired Connections Last mile connection Link between a customer and ISP Most last mile connections use copper wiring Copper-based digital communications lines (T1) Require the signal to be regenerated every 6,000 feet (1.8 KM) Last mile delivery of telephone and data lines has long been a problem for the carrier Must be able to justify the cost of installing wired connections to remote areas Last Mile Wireless Connections Microwaves are higher frequency RF waves In the 3 to 30 GHz range of the electromagnetic spectrum known as super high frequency (SHF) band Microwave towers are installed roughly 35 miles (56 kilometers) apart from each other A microwave link operating at 4.0 GHz carries 1800 voice calls simultaneously Fixed wireless Wireless as the last mile connection for buildings Backhaul connection Company’s internal infrastructure connection Baseband vs. Broadband Broadband transmission Sends multiple signals at different frequencies Baseband transmission Treats the entire transmission medium as if it were only one channel Only one signal can be sent at a time Land-Based Fixed Broad