ential problems early. We can then maintain and grow a healthy network, offering high-quality service to the maximum number of users we can support. We also can detect early signs of growth in usage or changes in usage patterns and respond before QoS is affected. This lead time allows us to get changes in place before customers experience poor service, or at least before they ex- perience a lot of poor service. The more we know about exact network usage patterns and capacity performance, the more we can tune our network rather than overengineer it. And a finely tuned network is more cost-effective and therefore more profitable than an overengineered network. A network operations center (NOC) can monitor and record the status of all network equipment and links across a continent. The NOC monitors the performance levels dis- cussed in this chapter and also monitors the network for outages and equipment or link failures, allowing prompt dispatch when problems do occur. Sometimes, however, rapid subscriber growth can lead to problems before we are aware of them through monitoring. In such a case, we need to be able to turn user com- plaints into useful data. This is the topic of Chap. 40. 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 Turning User Complaints into Useful Data How many times have you had a cellular telephone call drop or given up and hung up due to static but not called to report the problem? Most users suffer poor service and do not complain until one day they change vendors, and we lose their business. The complaints we do get each represent many problems we never hear about at all. There- fore, it is essential that we take every complaint seriously and use it as information that can help us improve our systems. Service complaints describe the user's experience, the symptom