WCDMA is an interference limited multiple access technique .It is widely used in the 3rd generation mobile networks like UMTS. When a new call arrives in the system to get admission, it checks whether the call is admitted or not based on some parameters like signal to interference ratio (SIR), transmission power of the Node B and the air interface load .If the call is accepted this will increase some interference to the ongoing calls. This new interference would degrade the ongoing calls and this will also add some extra load which may also lead to the exceeding capacity. So that the system has to decide this admission policy in a systematic way that all the users should maintain their communication with guaranteed quality of service. This decision making algorithm belongs to the radio resource management functionalities of the Radio Network Controller (RNC) in a WCDMA based UMTS network. This thesis paper focuses on the mathematical representation of the call admission control in an interference based environment. There is also a comparative study with different methods.