Optimal traffic balancing scheme in small cells between licensed and unlicensed bands

In order to increase the network capacity and alleviate the problem of scarcity spectrum, LTE in unlicensed band (LTE-U) has been proposed recently and provides a large amount of potential interests for most operators and companies (e.g., Qualcomm, Nokia). But because Wi-Fi has been widely used in unlicensed bands, how to offload the traffic from licensed bands to unlicensed bands is one of the crucial problems for LTE-U. To solve this problem, we introduce the system model of heterogeneous networks where LTE-U coexists with Wi-Fi and propose a new optimal traffic balancing scheme for small cells to assign traffic over several licensed bands and single unlicensed band which use the same power budget. Then we extend the new optimal traffic balancing scheme to the multi-unlicensed-bands case and develop a new fast algorithm to quickly achieve this optimal scheme. Finally, we make the simulations on both cases.