 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 users with half the path gain (or twice the path loss) to another serving antenna look like five users over there.2 The forward direction for multiple servers is surprisingly similar: TM = N (28.19) Equation (28.19) is the matrix equation, and Eq. (28.20) is the same system of equa- tions written out the long way: T1m11 + T2M21+++++ 1 N1 T1m12 + T2M22 + TkMk2 N2 (28.20) Tb is the total transmit power requirement for antenna face b, and Nb in Eq. (28.21) is the same noise component we saw in Eq. (28.10): (28.21) That the M matrix for reverse and forward directions is the exact same matrix is beautiful and wonderful result.³ Mathematician types would call it elegant. The single- server analysis tells us that there is a single component m, or Mbb in the matrix case, for both reverse and forward same-cell interference. The multiple-server analysis tells us that there is a single term Mbc for the interference between antenna face b and users served by antenna face C. The analysis goes on to tell us that the interference from one cell sector to another is completely described by the difference in the radio signal paths, the ability of the wireless telephone system to separate the radio environments of its cell sectors. 28.1.3 Wireless local loop (WLL) capacity These equations tell us that wireless local loop can have a fantastic capacity advantage over wireless mobile telephones. An antenna mounted on the side of a building can be a narrow-beam, directional, high-gain antenna pointed directly at the serving base sta- tion. A directional antenna at the user terminal reduces the interference from that user terminal to other cells in the wireless telephone system. This appears as a reduction in the cell-to-cell interference terms, Mbc, in M. There is on