Efficient Route Optimization Methods for Femtocell-Based All IP Networks

Recently, femtocells, which cover a cell area of several tens of meters, have been attracting considerable attention in mobile communications. When a femtocell is connected through a public network, such as a broadband access network or the Internet, a secure tunnel is established between the femtocell and the security gateway located in the mobile core network and media data are sent and received over that tunnel. Therefore, if the security gateway is far away from the femtocells and those femtocells are in close proximity with each other, the routing path of the media data between users becomes redundant. Moreover, the intensive processing due to encryption and decryption for the media data protection could impact on the load of the security gateway. In this paper, we propose efficient media path optimization mechanisms by sending and receiving media data directly between femtocells in coordination with IMS (IP multimedia subsystem), which is expected to be a core technology for session control in an all-IP network, and evaluate the proposed mechanisms using a commercial femtocell.