Device and Method of Handling Cellular Network and Wireless Local Area Network Radio Level Integration with Internet Protocol Security Tunnel

A communication device of handling a Cellular Network and Wireless Local Area Network (WLAN) Radio Level Integration with Internet Protocol Security (IPsec) Tunnel (CWIP), comprising:

• a storage device, for storing instructions of:
• having a cellular connection with a base station (BS) of a cellular network;
• receiving a first Internet Protocol (IP) address from the BS via the cellular connection;
• receiving a CWIP configuration configuring a second IP address for establishing a first IPsec tunnel for the CWIP from the BS;
• having a WLAN connection with a WLAN, and receiving a third IP address for transmitting at least one IP packet via the WLAN, from the WLAN via the WLAN connection;
• establishing the first IPsec tunnel via the WLAN connection to the second IP address by using the third IP address, when having the cellular connection;
• generating a first IP packet of the at least one IP packet and setting a source IP address of the first IP packet to the first IP address;
• and
• transmitting the first IP packet to the BS via the first IPsec tunnel, when having the cellular connection;
• and
• a processing circuit, coupled to the storage device, configured to execute the instructions stored in the storage device.