ABSTRACT
Contents 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 9.2 Cellular WMAN Architectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
9.2.1 Single-Cell Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 9.2.2 Frequency Reuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 9.2.3 Propagation Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
9.3 Interference Scenarios in TDMA-Based LMDS . . . . . . . . . . . . . . . . . . . . . 282 9.3.1 General Considerations and Interference Scenarios . . . . . . . . 282 9.3.2 LOS Analysis and Correlated Rain Fading . . . . . . . . . . . . . . . . . . 285 9.3.3 Nearly LOS Analysis and Shadow Modeling . . . . . . . . . . . . . . . . 289 9.3.4 Three-Dimensional Analysis: The Effect of Elevation
and Building Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 9.4 An Alternative Access Solution: CDMA-Based LMDS Networks . . . 293
9.4.1 General Considerations and Interference Scenarios . . . . . . . . 293 9.4.2 Comparison between TDMA-and CDMA-Based LMDS
in Terms of Intercell Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 9.4.3 Correlated Rain Fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
9.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
9.1 Introduction Wireless metropolitan area networks (WMAN) operating in the millimeterwave range are usually referred to in the literature under the broad term fixed broadband wireless access (BWA), which encompasses a plethora of fixed wireless systems. Among others, the term fixed BWA includes LMDS (local multipoint distribution service) networks [1,2] operating in licensed frequency bands above 20 GHz. Specifically, the International Telecommunication Union (ITU) in Europe and the Federal Communications Commission (FCC) in the United States have allocated spectrum in the range 24.5-26.5 GHz/40.5-43.5 GHz and 28 GHz/38 GHz, respectively, for implementing LMDS. Furthermore, the air interface specified in recent technical WMAN standards issued by the IEEE (802.16 WirelessMAN [3]) and ETSI (BRAN HIPERACCESS [4]), covers frequencies from 10 GHz to 66 GHz to provide access at high data rates (up to approximately 100 Mbps). These two standards constitute the WiMax∗ forum, aiming at the convergence and interoperability of the two technologies.
