A low-complexity fuzzy-logic-control-based vertical handoff decision algorithm with rough set theory

In many vertical handoff decision algorithms, various factors, such as the received signal strength, the available bandwidth, monetary cost, residual battery and so on, need to be taken into account to make a handoff decision. Among different kinds of vertical handoff decision (VHD) schemes, fuzzy-logic-based VHD algorithm has an advantage in dealing with incomplete and uncertain information. However, the computational complexity of fuzzy-logic-based VHD method follows an exponential increase with the number of input parameters, which limits its practicability. In this paper, a low-complexity fuzzy-logic-control-based (FLC-based) VHD algorithm is proposed for heterogeneous wireless networks. In proposed FLC-based VHD algorithm, a technique on the basis of rough set theory is put forward to reduce fuzzy logic decision rules and select core parameters as input criteria. Using these core parameters in fuzzy logic controller, the value of access network candidacy is estimated. And VHD is made based on access network candidacy. Simulation results show that the proposed low-complexity FLC-based VHD algorithm can dramatically reduce the handoff decision time, as well as achieve almost the same network selection performance compared to the original FLC-based VHD algorithm, and better network selection performance compared to the FLC-based VHD algorithm with the same number of input parameters.