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Rearranging (5.11) in terms of energy of a single bit per user per bandwidth,we have23CB ¼ log C=N62 1 þ B 1 þ C 74N ðl 1Þ5ð5:12Þ¼ log 2 1 þ r b =B E b =N 0B 1 þ r b =Bðl 1ÞE b =N 0which can be rewritten as EC x ¼ log 2 1 þ C b =N 0x1 þ C x ðl 1ÞE b =N 0ð5:13ÞOr, equivalently,E b 2 C x 1¼N 0 C x l 2 C ð5:14Þ½ x ðl 1ÞŠwhere C x ¼ r b =B =B.The plot of (5.14) is shown in Fig. 5.9 for variable number of users, lWe observe in Fig. 5.9 that the larger the number of users, the smallerthe allocated channel capacity with increased noise tolerance level. However,for a large number of users we can use well-known power-series approxima-FIGURE 5.9Normalized capacity of noncooperative CDMA system.Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.