ll need to be provided at lower and lower cost as they are included in existing equipment or given away at low cost or for free as incentives for choosing cellular service. 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. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter The Base Station The base station is the critical component of a cellular network technically, economi- cally, and oddly enough, aesthetically as well. In system terms, we can define the base station by its two interfaces: a noncellular pipe back to the mobile switching center (MSC) and public switched telephone network (PSTN) and an air-interface link using the system's cellular standard [Advanced Mobile Phone Service (AMPS), Global System for Mobility (GSM), code division multiple access (CDMA)] to the user terminals oper- ating within the cell. On the air interface, the base station transmits the forward (downlink) radio signal and receives the reverse (uplink). As an engineering compo- nent, the base station is a unique technology that creates the cellular structure. Of course, every component of the cellular system has a crucial function, but base stations, due to their combination of telephony and radio components, are more specialized than, for example, MSCs, which are largely telephone switches adapted to cells. The engi- neering of the base station as a whole determines the reliability of the cell, and the en- gineering and management of the air interface are the most critical components in op- timizing cell capacity and quality. Economically, base stations are expensive to build, and a cellular system needs a lot of them. Also, due to their remote locations, they are often expensive to repair as well. Aesthetically, they are considered a nuisance in most neighborhoods, and this con- strains their height and location and adds considerably to their cost. In this 