UMTS Terrestrial Radio Access Network (UTRAN) Transport Network Layer dimensioning has been of great interest among network researchers and planners due to the limit of Iub bandwidth. This paper investigates the potential impacts caused by Connection Admission Control (CAC) mechanism of the air interface and User Mobility (UM) on simulations carried out for the UTRAN transport network domain. Independent from the TNL CAC mechanism of the transport network which is in charge of Iub link bandwidth, the Radio CAC function deals with the highly non-linear resources needed for an attempted connection depending on its specific propagation and interference situation. The consideration of the air interface acting as bottleneck results into a less challenging amount of traffic for the transport domain. In addition, mobile user behaviors, e.g. UM, may dynamically change traffic load at the air interface, and in consequence affect Iub load, which has a very close correlation with cell load. In this work, a simulation model with Radio CAC mechanism and Handover strategies is implemented to study this correlation, and evaluate the UTRAN transport network performance given a limited radio capacity. The analysis on the impacts of the Radio CAC and UM are derived from qualitative simulations.
