Fast and Optimal Beam Alignment for Off-the-Shelf mmWave Devices

Overcoming the very high path loss is considered a prerequisite for operating millimeter-wave (mmWave) beamforming to meet the high data-rate requirements of next-generation wireless systems. Existing work chose the optimal beam pattern outside the codebooks to maximize the SNR. However, it is nontrivial to quickly find the optimal beam for off-the-shelf mmWave devices, especially as the standardization efforts are moving towards incorporating large-scale antenna arrays. In this paper, we present SWIFT, a system that can significantly reduce the beam scan time while achieving optimal beam alignment for off-the-shelf mmWave devices. To implement SWIFT, we tackle algorithm complexity and calibration cost, making SWIFT independent of any phase measurements and instrument or specialized circuitry. Our results show that SWIFT can achieve near-optimal SNR performance on the off-the-shelf devices and significantly save beam scan time over the state-of-the-art. Our design is generic and has the potential to scale to future-large scale antenna arrays (e.g., massive MIMO in 5G and beyond).