Device and Method of Handling Radio Resource Control Connection Resume Procedure

A method of handling a radio resource control (RRC) connection resume procedure between a first layer and a second layer of a communication device, the method comprising:

• the first layer transmitting a first request message for establishing a RRC connection and at least one first identity parameter to the second layer;
• the second layer establishing the RRC connection with a network, after receiving the first request message and the at least one first identity parameter from the first layer;
• the second layer receiving a RRC suspend request message from the network;
• the second layer suspending the RRC connection and transmitting a suspend indication to the first layer, after receiving the RRC suspend request message;
• the first layer entering a first idle mode with suspend indication, when receiving the suspend indication;
• the second layer not releasing the at least one first identity parameter received from the first layer, when the RRC connection is suspended;
• the second layer storing the at least one first identity parameter;
• the first layer in the first idle mode with suspend indication transmitting a second request message for resuming the RRC connection to the second layer, after receiving the suspend indication from the second layer;
• the second layer transmitting a RRC connection resume request message to the network, after receiving the second request message from the first layer;
• the second layer receiving a first RRC connection setup message from the network, after transmitting the RRC connection resume request message to the network;
• and
• the second layer transmitting a first RRC connection setup complete message comprising the at least one first identify parameter to the network, after receiving the first RRC connection setup message from the network.