This base station performs also as a mini-RNC/BSC, generally capable of performing layer 1, 2 and 3 functions. There are two types: serving BTS and drift BTS (equivalent to serving RNC and drift RNC in a WCDMA radio network). (IP) servers: The IP base station is not capable of performing all the RNC/BSC functions, which are of network level. These servers handle the signalling between the network elements. They are capable also of auto-tuning the parameters of the radio network, leading to better utilization of radio resources. As there are multiple technologies to be handled, a common server improves the performance and efficiency of the network in comparison with separate servers for each of the radio interfaces. Gateways (GW): These are responsible for the interaction of the IP-RAN and IP-Core networks. They are usually of two types, CS-GW and PS-GW, based on the type of call (circuit-switched or packet-switched) it is capable of handling. Network Planning for the All-IP Network Network planning covers the access (transmission) network and the packet core network. Figure 10.3 shows a small box with the core network as a subset of the packet core network, indicating that voice traffic will still be a part of mobile communications, but it will travel on the packet core network (as opposed to the circuit core in 2G and 3G networks). Access Packet Core Network Network Circuit Core Figure 10.3 Network planning for an All-IP network Process and Protocol Overview The transmission network planning process is similar to that discussed in Chapter 8. The process thus starts with dimensioning and pre-planning, followed by detailed planning and implementation. The main steps in pre-planning will be: dimensioning the number of network elements such as IP base stations, servers, PS- (and CS-) core network elements etc. dimensioning the capacities of 'open' interfaces tackling inter-operability issues between the GSM/UMTS/WLAN networks. Transmission and core network planning are more dependent on each other compared with 3G n