ADMISSION CONTROL

Admission control function admits or denies new users. AD mechanism consists of two main step:

1. RAB Matching : This performs the mapping of the requested RAB onto a supported radio Bearer configuration. This step includes a RAB radio bearer mapping table which provides the means to admit a RAB at a rate lower than the requested Max bit rate according to the cell load. This function, which is called intelligent RAB mapping, only applies to a RAB with an interactive or background traffic class.
2. Call Admission control: THis is the function located in the CRNC responsible for deciding whether a request to establish a radio access bearer can be admitted in the UTRAN or not based on the available resources. Radio CAC is based on power and OVSF codes in the DL and on interference in the UL that other CAC function are performed at the transport. NodeB and RNC levels.

CAC is applied: 

• On initial admission
• On RB reconfiguration: Such as RB bit rate downgrading/upgrading, cell_Fach to Cell_Dch transition..
• On mobility: SHO, inter-frequency HHO and 2G to 3G HHO.