t the website. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter Mobile Switching Center (MSC) Growth Our mobile switching centers (MSCs) and auxiliary equipment must grow to meet the capacity demands of our ever-growing cellular network. In this chapter we will exam- ine when to upgrade MSC equipment, how to assign users and base stations to new MSCs and deal with MSC borders, and options for MSC placement, equipment provi- sioning, and auxiliary equipment. 43.1 Determining When to Upgrade MSC Equipment As the subscriber traffic grows, the MSC will run out of critical resources to serve that traffic. As this happens, we will have to buy more MSC equipment to keep up with sub- scriber demand. As in the case of base station equipment planning, this is an ongoing process. While adding MSC equipment is a simpler process than site planning for new cells, increasing subscriber demand for an evolving mix of services can keep planners busy figuring out which MSC components need to expand to meet the growing demand for service. It is important that the MSC maintain enough capacity for peak-hour demand. Hav- ing the switch run out of capacity, even for 5 minutes during the busy hour, means no- ticeably degraded service over a large area with many subscribers. Each component of the MSC has its own limitations and its own time-of-day demand cycle. Of course, the time-of-day demands on MSC components will be highly correlated with each other, but it is possible that the mix of services will be different at different periods during the day. Peak-load processing increases with call processing, short message service (SMS), other signaling, and handoffs, as discussed in Sec. 24.1. Growth in call volume, in- creasing popularity of short messages, and more mobile subscribers will drive us to in- crease the MSC processing power. A trend toward longer calls or data services may have the opposite effect because they generate less call-processing activity. Increasing use of multimedia message service (MMS) ties up a lot of code d