mised design of the network identifying selected network architecture and the required number of sites and equipment needed during roll-out of the network. The network design can be achieved through several planning phases (Figure 4.11). The designed network should be able to carry the total traffic at the end of each phase. The pace of the subscriber growth determines the phases. At the end of each phase the master plan should be reviewed and where necessary modifications for the upcoming phases can be made. When several planning phases are required the last phase is optimised first. The network should then be dimensioned such that there is no unnecessary capacity introduced that is not needed in later phases. Planning is generally an iterative process. The network architecture and topology can be selected with the inputs collected, based on the coverage area of each element. Each network element is dimensioned according to site location and subscriber/transmission capacity per road map. In the release 4 split architecture, the user plane and control plane are calculated separately. The end-to-end signalling traffic 3GPP Release 4 Circuit Core Network is calculated between the network elements. The traffic can then be routed based on the interconnection of the elements. It is important to check that the load on each element in terms of processing capacity and number of interfaces does not exceed its nominal capacity. Calculate the transmission needs to implement the chosen configuration. If the network element capacity or interface is exceeded, then a repeat of the iterative process is required until an optimal solution is found. User Plane Planning As one of the innovative aspects of the 3GPP release 4 network is the separation of the user plane and control plane, the location and coverage areas can be defined for both the MGW and MSS/GCS. In brief, the user plane planning process can be summarised as follows: Determine the number of MGWs, site locations and coverage areas. Calculate end-to-end traffic matrices