Online Packet Dispatching for Concurrent Transmissions in Heterogeneous Multi-RAT Networks

The heterogeneity of different radio access technologies (RATs) in the tightly integrated multi-RAT networks can be exploited to support bandwidth hungry applications. However, the out-of-order problem due to concurrent transmissions over multiple RATs may compromise the performance gain if packets are not well dispatched between different RATs. In this paper, we address this problem by adopting value function as a measure of the admittance cost based on current RAT and queuing states, with which the online packet dispatching problem is formulated as a nonlinear mix-integer programming problem. We obtain the close-form solution for this problem for the special case of two RATs and design a gradient algorithm based on the dual decomposition technique for general cases. Simulation results show that the proposed scheme significantly reduces the delay variation over different RATs, which is effective in alleviating the out-of-order problem in concurrent transmissions.