distance telephone service in the United States. The 1984 divestiture ruling formally sanctioned competition in the long-distance arena. Microwave offered great cost efficiencies because no cables had to be laid, allowing a new entrant to easily build a network of long-haul trunks to serve busy routes. The role of microwave has been greatly expanded since the 1980s, with appli- cations in just about every network domain. It is beyond the scope of this discus- sion of basic characteristics to go into detail on all the options available today, but detailed coverage is provided in Part IV. The following is a summary of the wireless systems that rely on microwave: Wireless wide area networks (WWANs)-In the context of WWANs, microwave is used to support 2G cellular PCS services (TDMA, GSM, CDMA), 2.5G enhanced data services (GPRS, HSCSD, EDGE), 3G high- Satellite speed data and multimedia services (W-CDMA, UMTS, CDMA2000, TD- SCDMA), 3.5G IP backbones (HSDPA, HSUPA, HSOPA), and 4G mobile broadband systems (using OFDM and MIMO technologies). WWANs are discussed further in Chapter 14, "Wireless WANs." Wireless metropolitan area networks (WMANs)-When it comes to WMANs, the microwave spectrum is used in support of broadband fixed wireless access (BFWA) systems, IEEE 802.16 WiMax standards, the Korean WiBro specification, ETSI's broadband radio access network (BRAN), HiperMAN and HiperAccess, Flash-OFDM, IEEE 802.20 Mobile- Fi, iBurst Personal Broadband System, IEEE 802.22 Wi-TV standards, and virtual fiber or millimeter wave technology. WMANs are discussed further in Chapter 15. Wireless local area networks (WLANs)-The ever-so-popular WLANs, including the IEEE 802.11 family of protocols and ETSI HiperLAN and HiperLan2, operate in the microwave band, relying on the unlicensed bands of 2.4GHz and 5GHz. WLANs are discussed further in Chapter 15. Wireless personal area networks (WPANs)-WPAN standards make use of unlicensed portions of the microwave spectrum, including IEEE 802.15.1 Bluetooth, IEEE 802.15.3 WiMedia, Ultra-Wide