Beam Broadening for 5G Millimeter Wave Systems

Fifth generation (5G) wireless systems will use higher frequency bands (24GHz-70GHz), the so-called millimeter wave frequencies in order to achieve higher capacity. These systems rely on using large antenna arrays and narrow beamforming to counter the large path-loss experienced. Narrow beamforming maximizes array gain but results in a significant increase in beam management complexity, and is sensitive to channel dynamics as well. This, in-turn attracted attention towards beam-broadening algorithms, where a trade-off between high transmission quality and robustness can be achieved. In this paper, a novel beam-broadening algorithm based on Sequential Quadratic Programming (SQP) is proposed. Numerical results show up to 3 dB performance gain in comparison to competing beam broadening algorithms. It is worth noting that the performance gain is achieved at no additional cost.