The present invention provides a method using Q-learning rule to accurately estimate the transmission cost for the multi-rate transmission control (MRTC) for RRC (radio resource control) in the WCDMA network. This method comprises the following iterative steps: first obtaining a system state and an action using an incoming request, a mean of interference and a variance of interference, then obtaining Q values based on the system state and the action. Afterwards, allocating an optimal action with the Q values, and when a new request with a new state arrives, going back to the first step and updating the Q values using the new state and a cost function based on the system state and the action.