hitecture as the first radio system relying on managed interference. In Chapter 7, "TDMA Wireless Telephony (GSM)," we introduce the world's first and largest digital cellular system, Europe's Global System for Mobility (GSM) time division multiple access (TDMA) technology, which is serving about 700 million users worldwide in 2002. Having built a solid background in the fundamentals of radio and the evolution of cellular telephony, we turn to code division multiple access (CDMA) in Chapter 8. In Chapter 8, "The CDMA Principle," we discuss the underlying concept of CDMA, called spread spectrum, the mathematical derivation of the CDMA method of managed same- cell interference, and the principles of key CDMA components such as the rake filter and power control. We also describe how CDMA operates in both the forward and reverse directions and how it performs handoffs as subscribers move from cell to cell. The CDMA cellular networks our readers support embody both concepts developed for the first analog cellular systems and also the latest digital chipsets and technologies. With the background provided in Part I, "Key Radio Concepts," cellular engineers will be well prepared to understand the latest CDMA technology so that we can design and optimize today's CDMA networks. 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 Radio Engineering Concepts We all know what radio is, at least enough to get by. This chapter is for our readers who came to cellular from landline telephony or information technology and for those who want a refresher in the basics of radio engineering. 1.1 Radio Radio is electromagnetic radiation, a changing electric field accompanied by a similarly changing magnetic field that propagates at high speed, as illustrated in Fig. 1.1. A ra- dio wave is transmitted by creating an