e user re- ceivers as if all that noise were broadcast from the antenna face. The total antenna face transmit power T for all the users is expressed in Eqs. (28.11) through (28.14): xT = (b - 1)T + N (28.11) (a ++1-6)T=1 N (28.12) (28.13) (28.14) As in the reverse direction, the forward direction has a severe limit at a + 1 users beyond which no amount of power is sufficient. The graph of total forward power T as a function of users shown in Fig. 28.2 has a different shape1 with the same basic idea: 1The reverse power curve is a hyperbola with asymptotes at r = 0 and = a + 1, whereas the forward direction has an extra linear component. The forward noise value N increases linearly as increases, whereas the reverse noise n does not. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CDMA Principles for Multicellular Systems Capacity and Quality Principles Number of Users Figure 28.2 CDMA forward power requirement as a function of number of users. Forward power requirements remain very low until gets very close to a. The reader should notice the pleasing symmetry of the same m value, mr = n and Tm = N, in Eqs. (28.3) and (28.13). 28.1.2 Multiple servers For multiple antenna faces, the algebra gets more complicated, but the basic idea stays the same. We need to maintain the distinction between the users in the cell sector be- ing served and the base station antenna face serving them. We refer to the antenna faces as b and C and the sets of their users as B and C. Thus the notation U E B means all the users in the cell sector served by antenna face b. It makes no difference for this analysis whether the two serving antenna faces b and C serve sectors in the same cell or sectors in two different cells. If a full-blown CDMA system has 500 cells and each cell has three sectors, then the total number of antenna faces and sectors, k is 1500. When we writ