C) Planning Planning for CDMA Capacity workload relatively evenly among the MSCs and to control the amount of inter-MSC communication. The first job of the base station assignment is to balance the workload. If we as- sume that each base station generates the same amount of MSC activity, then we start the assignment by assuming that we will divide the base stations evenly among the MSCs. It is not necessarily true that each base station uses the same amount of MSC re- sources. Some have more CDMA carriers than others, and some may have more an- tenna faces than others, so these base stations will generate more call activity. Also, base stations with a high fraction of data-service subscribers will use different MSC re- sources than those with mostly voice subscribers. In considering the demand that a base station places on an MSC, it is best to focus on the resources that are most scarce, as determined by the lower bounds given in Sec. 34.3, where we define the one resource driving the MSC count. Base stations requiring more of that resource can be said to re- quire more of the MSC's most critical resource. For example, if processor capacity is the resource driving MSC count, then a base station that is busy with 3G data traffic is ac- tually using relatively little of the MSCs most critical resource. However, it can be valu- able to identify base stations that are heavy users of resources that are nearing capac- ity, even if they were not the resource defined as critical during planning. Base stations serving primarily voice calls will have more call processing and less packet data than those serving primarily data service. The result of the base station assignment is an even distribution of workload. This workload should be calculated in terms of whichever MSC components were the limit- ing factor in deciding how many MSCs to use. The assignment also should manage the inter-MSC borders discussed in the next section. 34.5 Inter-MSC Borders In a multiple-MSC wireless telephone system, we can think of the MSC regi