Beamforming and Power Allocation for Coexistence of Massive MIMO Cellular Network and WiFi Network

The coexistence technique is a promising solution to provide enhanced fifth-generation (5G) services by sharing unlicensed bands with WiFi systems. In this paper, we study beamforming design and power allocation in massive Multiple Input-Multiple Output (mMIMO) cellular multi-cell system coexisting with Wireless Fidelity (WiFi) network. We design the beamforming matrices based on the Block Diagonalization (BD) method in licensed and unlicensed bands in order to create spatial nulls for interference suppression on the users of adjacent cells and the WiFi devices, respectively. In the following, the power allocation problem is formulated as a convex optimization problem to maximize the achievable sum rate while one must guarantee the minimum quality of service (QoS) corresponding to each central cell user. The formulated problem is solved by the classical convex optimization method and we present a proposed algorithm to obtain the optimal solution. In the simulation results section, it is shown that the proposed beamforming and power allocation algorithm (PAA) outperforms the conventional benchmark methods. Also, it is indicated the output of PAA is significantly close to the output of the Matlab CVX toolbox.