 it fits well with its small packet size for use in real-time connections like traditional voice. In Iu-ps however, the services are different and less sensitive to delays, SO AAL5, which has a larger packet size, is chosen as the adaptation layer, which means, for example, less overheads. In addition to Iu-ps, IP, UDP and GTP-U protocols are also used for layers 3 and 4 to provide as close as possible the full flexibility and gains of packet switched data communication networks to the WCDMA transmission network. Signalling in the WCDMA Access Network There are three main categories of signalling that can be distinguished in the WCDMA transmission network. These are signalling for transport, signalling for the WCDMA system and signalling between the radio network controller and the user element. Transmission Network Planning and Optimisation Transport Signalling Signalling for transport means signalling to establish and release AAL2 connections for user plane connections. The signalling itself is done using AAL5 connections. This signalling is needed everywhere where AAL2 connections are used, i.e. in Iub, I-cs and Iur interfaces. AAL2 signalling (Access link control application protocol, or ALCAP) bandwidth dimensioning is directly proportional to the amount of connection establishments and releases, which is then further directly proportional to the average length of service usage, network bandwidth reallocation capability and policy, mobility of the users and soft handover policy. The average use of traditional voice services is still reasonably easy to predict and project against changing call plans, but forecasting the user behaviour with new services provided by the WCDMA network is challenging. It is even more difficult bearing in mind that it might depend on adjustable or fixed system parameters when there is an automatic release time for AAL2 connections of different services. In other words, if that is the case then user behaviour for the average idle time (e.g. reading time) per service should be forec