sion As the market for CDMA services continues to evolve, business models will need to be adapted. Subscriber growth is slowing, and the increased churn and the ups and downs of a competitive market need to be taken into account. Multiple service offerings compete for the same air-interface resources. Each offers a different rate of return and has a dif- ferent and as yet unknown popularity with subscribers. Business and engineering teams are most likely to succeed if they cooperate closely with one another to determine the best investment of available funds in the relative growth of different service offerings. 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 Propagation Models Modeling propagation allows us to plan locations and design of our base stations for better cell coverage with less interference. The basic approaches to modeling and im- plementing code division multiple access (CDMA) cells contain some interesting con- trasts from methods used for conventional-reuse systems. The problems that arise are not the same. There are different models of radio propagation, each requiring different inputs. The best model for our system depends on a number of factors, such as the type of terrain over which we are providing coverage and the size of the cells. 47.1 CDMA Issues and Challenges As students of CDMA, we can scoff at the trials and toils of those who manage conventional-reuse systems with their intricate channel-set-reuse paradigms and the complexities involved with multiple cell sizes. While they pore over their "most likely interferer" maps trying to track down a problem in North Lake caused by too strong a signal across town in Springfield, we sit quietly knowing that our N = 1 CDMA system has no channel assignment issues and balances power second by second. As students of capa