Method and system for transmitting/receiving data in heterogeneous communication systems

A system for transmitting/receiving data in heterogeneous communication systems comprising a mobile station, a first communication system, the mobile station currently accessing the first communication system, and a second communication system having an access scheme different from the first communication system, the system comprising:

• a mobile station for accessing the first communication system and maintaining a first active session with the first communication system, accessing the second communication system and requesting a second active session to the second communication system when sensing handover to the second communication system while the first active session with the first communication system is maintained, maintaining the first active session with the first communication system by means of the second active session with the second communication system created according to the request;
• the first communication system seamlessly transmitting traffic to the mobile station through the second active session with the mobile station and the second communication system, the mobile station having performed handover to the second communication system;
• and
• the second communication system transmitting the traffic from the first communication system to the mobile station through the first active session with the mobile station and the first communication system, the mobile station having performed handover and having accessed the second communication system,
• wherein the mobile station receives an Internet protocol address from the second communication system, and wherein the Internet protocol address is identically allocated from the first communication system, and receives traffic from the first communication system based on the Internet protocol address,
• wherein the mobile station receives the traffic from the first communication system through the second communication system by means of tunneling established between the first communication system and the second communication system based on the Internet protocol address,
• wherein the mobile station acquires the first communication system, receives an Internet protocol address from the acquired first communication system wherein the Internet protocol address is allocated from the first communication system, receives traffic based on the Internet protocol address, and maintains the first active session with the first communication system.