es, reducing its degree of freedom, and then manage the tradeoff between the other two components. Since we can choose to constrain any one of the three variables, this gives us three options. We can fix the amount of traffic we will serve. Once the number of subscribers and their usage patterns are fixed, we have a tradeoff between cost and quality of service (QoS). We can spend money on more CDMA capacity to offer lower blocking and lower occupancy. This means that subscribers will see fewer ineffective attempts and higher call quality. Their data links will have faster response times and higher average rates over time. The service provider has to determine how willing the subscribers are to pay more for these improvements. We can fix the budget for the wireless telephone system. A fixed amount of money buys a fixed amount of CDMA capacity, and we have a tradeoff between traffic and quality. We can continue to add subscribers to the system, or we can encourage those subscribers to use more air time or more services. As the usage increases, the system has higher call blocking and more data delays. Since most service providers are loathe to turn away new subscribers, this road usually leads to the lower-quality choice. Finally, we can fix the QoS. We can decide that the wireless telephone system will meet specified targets of ineffective attempts, lost calls, lousy calls, slow bit rates, and data errors to its voice, data, and other subscribers. This commitment may be a mar- keting decision, or it may be in a contractual form with service-level agreements (SLAs). Then we have a tradeoff between traffic and cost. As we add subscribers, we add carriers, sectors, and cells to maintain the QoS. This is closer to the mindset of the old telephone company engineers. These frontiers are not easy to find. It takes first-rate engineering and a lot of hard work to get the most CDMA capacity for the money we spend on a system. It takes keen marketing planning to offer the mix of services that generates the most revenue for t