e about the interaction between antenna faces b and c, the reader should remember that sometimes they will be al- ternative sectors on the same cell and sometimes they will be on completely different cells. In the reverse direction we get the matrix Eq. (28.15): (28.15) 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 CDMA Principles for Multicellular Systems This becomes Eq. (28.16) when written out the long way: M11r1 + M12r2 + M1krk=1 M21r1 + M22r2 + + M2krk N2 (28.16) Mk1r1 + Mk2r2 + Mkkrk - Nk rb is the received power for b users (that is, subscribers served by antenna face b), and Nb is the receiver noise level at antenna face b. The components of the matrix M in Eqs. (28.17) and (28.18) are the interactions of antenna faces and users of the same and other antenna faces: (28.17) (28.18) The matrix diagonal terms Mbb are the same as the m variable we had in the single- server case where Ob is the number of b users. The matrix off-diagonal terms Mbc for two different antenna faces b and C are the interference antenna face b causes for users served by antenna face C. Mbc reflects the interfering signal path from antenna face b to users served by c, as shown in Fig. 28.3. Another way to look at M is that each antenna face b is represented by a row in the matrix, Mb1, Mb2, , and each set C of users served by an antenna face is represented by a column in the matrix, M1c,M2c, Let us look a little more closely at the summation in Eq. (28.18). Mbc is the (negative) sum over all C users of the path gain ratio of b to C. This makes sense, really. If the path from C users to face C is twice as good as the path from the same C users to another face b, then their effect on face b should be half as much as their effect on face C. Ten Figure 28.3 Interference path from base b to C users. Downloaded from Digital