ed as follows: Sector 1. MAIO = 0, MAIO step = 2 Sector 2. MAIO = 1, MAIO step = 2 Sector 3. MAIO = 2, MAIO step = 2 Radio Network Planning and Optimisation Used frequencies at a given time for all TRXs, all sectors HSN starts MAIO Offset = 0 MAIO Step = 2. MAIO Offset = 1 MAIO Step = 2. MAIO Step = 2. MAIO Offset = 2. Sector 1 Sector 2 Sector 3 Figure 2.53 Example of synthesised frequency hopping Other Procedures Besides what is detailed in the previous sections, there are some operations that take place during the network life and that require advice from Network optimisation engineers. BSC Re-hosting Plan Review When adding new BSCs to the network, it is necessary to review the split plan (which site goes to which BSC with which Location Area Identity (LAI)). In defining a new BSC plan, it is fundamental to distribute sites properly depending on three criteria: Geographical distribution Intercell handovers BSC load Remember that geographically speaking, it is not recommended to use highways or high traffic roads as a frontier between BSCs, especially if they have different Location Area Codes (LACs). This is to avoid Radio Network Optimisation a handover ping-pong for high speed car mobiles. For the same reason (to minimise ping-pong), BSC frontiers are drawn between cells to minimize possible handover attempts between them. In addition to these two conditions, at the end, the BSC plan should respect a certain balance in the BSC load, which is calculated according to several elements according to manufacturer limitations. In general, however, the BSC load will be calculated as a ratio between the actual number of considered elements (TRX, PCM, BCFs (base control function), BTS (base transceiver station), TCH (traffic channel), etc.) and the maximum capacity of the BSC. Location area planning should also be considered. In fact, an LA constitutes a logical group of BTSs to which the same paging messages are sent instead of being sent to the entire network to inform one single mobile about an incoming call or SMS