uality Tradeoffs In the case of a wireless telephone system, the are many objectives and tradeoffs vy- ing for a decision maker's attention. Better service versus lower cost Volume of traffic versus sound quality Voice calls versus data services Faster data transmission versus higher availability Lower cost today versus higher revenue tomorrow Assured gains versus greater opportunity The answers that a decision support system provides to wireless telephone system en- gineers depend greatly on the input parameters to the optimization tools being used. 22.6.2 Capacity Even something as apparently obvious as capacity can have ambiguity of meaning. Coming from the telephone world, it is natural to define capacity as the number of voice calls a system can support over a specific period of time. In the next chapter, "Traffic Engineering for Voice and Data," we explore the relationship between the amount of subscriber demand and the system's ability to serve a high enough fraction of the call attempts. There are other issues of geographic distribution of subscriber demand and demand at different times of day. Also, as we move from 2G to 3G, we have a growing market for data traffic. A wire- less telephone system is unlikely to be optimized for voice and for data simultaneously. Making a better packet data environment almost certainly means making compro- mises in voice-call performance. Perhaps the system will allow fewer calls, or perhaps those calls will have poorer sound quality. We cannot evade these choices by looking away: If the engineers deploying a wireless telephone system do not address these is- sues, then they will be decided by the gods of chance. In the design of a CDMA system, capacity is not an absolute feature. Rather, voice capacity will be determined by quality-of-service (QoS) performance criteria. These in- clude the rate of ineffective attempts (call blocking), lost calls, and sound quality. We can serve more calls if we are willing to subject our subscribers to more static. Televi- sion commercia