Optimal beamsteering on D2D mmWave transmitters by employing general benders decomposition

The implementation of beamforming schemes on the base station side has been widely employed in recent communication networks. Thanks to the small size of microstrip antenna elements in millimeter-wave (mmWave) frequencies, the implementation of uplink beamforming in small-size user equipments (UEs) is now available and recently becoming popular. The practical implementation of beamforming on the UE side is limited by a variety of challenges and bottlenecks, of which the most significant are the hardware and software complexity as well as power consumption, and hence the low-complexity beamsteering techniques such as analog beamsteering is generally preferred to other schemes on the UE side. In this paper, we consider a mmWave D2D underlaid cellular network, wherein D2D UEs are equipped with low-complexity beamsteering capable antennas. The problem is then formally defined as to find the channel scheduling together with assigning optimal directivity angle and transmit powers of D2D UEs corresponding to the maximum throughput of D2D network. We will employ novel distributed solution approach based on generalized benders decomposition scheme. More specifically, we manage to obtain the closed-form solutions of the primal and master subproblems through which the optimal solution variables can be obtained in a low-complexity distributed scheme.