It also performs functions such as error checking, or carrying signalling for lower ATM layers. NBAP (on Iub): NBAP is of two types, common (C-NBAP) and dedicated (D-NBAP). C-NBAP is responsible for the handling of channels like RACH/FACH, cell configura- tions, fault management, etc. D-NBAP is required for the handling of dedicated/shared channels, air-interface fault management, configuration of radio links, etc. RNSAP (on Iur): RNSAP (radio network sub-system application protocol) is responsible for functions such as radio link management, physical channel reconfiguration, measure- ments on dedicated resources, compressed mode control, power-drift correction, error indications, UL/DL signalling transfers, etc. RANAP (on Iu): RANAP (radio access network application protocol) is responsible for paging, flow control, processor/CCCH overload at the UTRAN, cipher mode control, location reporting, resource checking, direct transfer, trace invocation, error handling, handover procedures, etc. Other Factors When a call is transferred from the base station to the MSC (for voice) or towards the SGSN (for data), overheads are added. As the RRM functions are located in the RNC, there are no soft handovers at the Iu-cs interface, SO no SHO factor is taken into account. However, factors such as blocking probability and signalling should be taken into account. If the call is a data call, some additional overheads are added especially related to the GTP protocol apart from the overheads added due to UDP, IP, etc. (refer to Figure 8.8(b)) and those related to signalling. RNC Dimensioning Another focus area is RNC dimensioning. It is dependent on the capacity of the RNC to handle: interface traffic (e.g. Iub/Iur/Iu) the number of TRXs the number of BTS. 8.4.3 Example of Transmission Network Dimensioning Consider an upcoming network for which transmission network dimensioning is to be done. The inputs required/given are as follows: Dimensioning is to be done for phase I only. 3G TRANSMISSION NETWORK PLANNING AND OPTIMISATION The