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View File - University of Engineering and Technology, Taxila

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FIGURE 8.12Tessellated clusters <strong>of</strong> cells, five cells per cluster.transmitting to mobile stations in their cells using the same frequency. This isco-channel interference. To deliver an acceptable speech quality to mobileusers, with minimum co-channel interference, the reuse distance d i must be atleastpffiffiffiffiffiffid i ¼ r c 3Nð8:10ÞIf the same b<strong>and</strong>width Df ch , but not the same frequency b<strong>and</strong>, is assigned toeach cell <strong>and</strong> each user is allocated a b<strong>and</strong>width Df u , then the maximumnumber <strong>of</strong> channels per cell isn c max ¼ Df chDf uð8:11ÞIf each cell covers an area A c , then the channels’ density may be expressed asd c ¼ Df chA c Df uð8:12ÞFading <strong>and</strong> Diversity SchemesIn addition to changes in polarization due to the Faraday rotation effect in theionosphere, mobile satellite communications have crossover from polarizationto polarization due to the structure <strong>of</strong> the mobile services. This rotational effectCopyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.

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