ANDSF-based WLAN offloading in the Evolved Packet System (EPS)

WLAN offloading has been identified as a novel solution to leverage the channel capacity crunch over the cellular networks. However, this solution does not consider the congestion states of the target access network and the method of selecting the best access for offloading. To assist the User Equipment(UE) with the discovery and selection of candidate access network for offloading, 3GPP in Release 10 introduce the Access Network Discovery and Selection Function (ANDSF), which contains preconfigured intersystem mobility and routing policies that can guide the UE to discover and select available access network for handover. The current ANDSF however, cannot make discovery and selection policies which reflect the current state of the available access networks. This can lead to the selection of unavailable or inappropriate access network for offloading. In this paper, we propose a scheme which incorporates a Network Event Reporting Function (NERF) at access network level, and enhancements to the ANDSF. The scheme obtains dynamic characteristics of the access networks, which are used as input to a Multi attribute decision making (MADM) module in the ANDSF to update the statically configured mobility and routing policies provided to the UE for access selection. The scheme provides the best access network for data offloading.