Asymmetric Links Beamforming for mmWave Overlay in LTE-Based Heterogeneous Network

Traffic offloading to the millimeter-wave hotspots is an efficient way to increase the throughput and spectral efficiency of existing LTE networks. Such approach can be considered as first step towards 5G systems, but before the millimeter-wave overlay realize its full potential, several important problems should be solved. Firstly, the millimeter-wave coverage should be increased up to several hundred meters - and this is possible not only with implementation of high-gain steerable antennas, and usage of special beamforming algorithms. Secondly, the MU-MIMO should be introduced in the mmWave standards, which lead to significant increase of simultaneously served stations and therefore, substantial increase probability of collisions between them. In this paper we will show that both mentioned problems may be resolved with the proposed asymmetric links beamforming procedure. This enhanced beamforming was initially submitted and accepted as part of upcoming next-generation millimeter-wave standard: IEEE 802.11ay.