Dual Connectivity Enabled User Association Approach for Max-Throughput in the Downlink Heterogeneous Network

The architecture of dual connectivity (DC) allows each user’s equipment to simultaneously communicate with a macro and a small cell via two different radio-interfaces. User association (UA) with DC is considerably more challenging than traditional single one, because each user must be associated with the best combination of serving macro cell and small cell. This paper focuses on DC architecture and proposes an efficient DC-enabled UA approach to maximize the overall system throughput for downlink wireless heterogeneous network (HetNet). In this approach, we formulate it as a non-linear and integer optimization problem in a sum-of-ratios form. Since the formulated problem is non-deterministic polynomial hard (NP-hard), it is challenging to achieve its optimal solutions. To this end, this problem is relaxed and then transformed into a tractable form, which can be solved iteratively to obtain its solution. Numerical results show that, compared with the existing methods, the proposed algorithm can enhance system throughput and improve offloading performance of small cells.