ath it which also constitute layer 2: RLC and MAC. MAC is an entity that forms the Iub interface and channels the information coming in from the RLC layer. The RLC produces information related to RRC signalling, CS and PS data. The RRC has two main states: idle and connected. In the idle state, a subscriber is not connected to the network. In the connected state, user equipment is performing data transfer activity (voice, CS or PS). For the UE to change state from idle to connected, the call admission function comes into action. The admission control (AC) resource management function controls the number of sub- scribers logged on to the network. It may admit or deny access to a new subscriber based on the resulting effect the extra subscriber would cause to the existing users. The result is based on algorithms that are executed in the RNC. These algorithms are also known as AC algorithms or CAC (call-admission control) algorithms. Admission control prevents congestion in the network and thereby maintains quality for the connected subscribers. AC 3G RADIO NETWORK PLANNING AND OPTIMISATION algorithms are executed separately for uplink and downlink, but a requesting subscriber can be admitted only after gaining clearance from the uplink and downlink algorithms. AC algorithms can be power-based or throughput-based. In the former, the uplink AC takes a decision based on whether the new subscriber mobile will increase the interference level over the planned load target and degrade the quality of the network. Each new user's entry affects the interference levels of the cell and adjacent cell. Thus, the interference level calculations are based on each of these cell measurements and the receiver noise. In throughout based calculations, both uplink and downlink AC take a decision on admission based on load factor calculations. The load factor has a direct effect on the interference margin (IM), as seen from the equation below: Interference margin = 10 log (7.2) where L is the load factor from equation 7.1 Interference doe