ioning. This is based upon subscriber capacity, geographical conditions, types of equipment available (in terms capacity), the type of routing employed, etc. Transmission connections: This refers to the interconnections between the switches and the actual capacities required for these transmission links. Transmission can be via op- tical fibre cables or microwave links (for dimensioning and designing the latter, refer to Chapter 2). Signalling plans: The various aspects of signalling such as routing, protection and related synchronisation should be planned during the network analysis and dimensioning phase. These plans constitute the major outputs of the dimensioning phase. Some typical ex- amples of switch and signalling network dimensioning plans are shown in Figures 4.8 and 4.9 respectively. Figure 4.8 shows an example of a big network. Instead of interconnecting the switches directly, transit switches have been used. Each region generates traffic from mobile, fixed Other Mobile Fixed Transit Other Tran 98 Mobile Other Mobile Fixed Transit Fixed Other Trans Mobile Transit Fixed Other Other Transit 498 Fixed Mobile Fixed Other Transit Mobile Fixed Other Figure 4.8 Typical output of switch network dimensioning CORE NETWORK PLANNING AND OPTIMISATION and other sources. The traffic is routed through the transit switches. The numbers shown in the figure indicate the traffic in milli-erlangs (mErl). Figure 4.9 shows a typical plan with signalling links and link sets (SLS), along with routing plans. This is a simplified example; in practice, more complicated networks involve more switches, and signalling plans become more complicated. Linkset = 12(MSC1), 2 SS7 Links Linkset = 11 (MSC1), HLR 1 4 SS7 Links Interactive Voice Response Linkset = 22 (MSC1), 6 SS7 Links MSC 1 Pre-paid Linkset = 22 (MSC2), 6 SS7 Links Linkset = 30 (MSC1), 4 SS7 Links Linkset = 20 (MSC2), 6 SS7 Links Linkset = 25 (MSC1), 4 SS7 Links MSC 2 Figure 4.9 Example of a signalling plan 4.6 DETAILED PLANNING Detailed planning of a core network generall