An overview of beam-tracking techniques for mmWave wireless communications

Millimeter-wave (mmWave) communication is the key to increasing the demand for high data rates and low latency resulting from the rapid evolution of wireless communications, especially in the fifth generation (5G) of wireless communication systems and beyond. The mmWave band suffers from high path loss and obstacle blockage, significantly reducing the transmission range. Note that high-directional beams are required to perform well in the mmWave band. Hence, beam alignment is crucial for high-data-rate transmission between the transmitter (Tx) and the receiver (Rx). One of the drawbacks is getting an accurate beam alignment when the transceiver (Tx, Rx, or both) is mobile. Beam tracking plays a considerable role in 5G communications, especially in vehicular communications, due to the repeated change of the transceiver (Tx, Rx, or both) position. This work presents an overview of the different beam-tracking methods used in mmWave communications, focusing on hybrid beamforming techniques. We also compare the various tracking techniques in a recommendation table. This overview suggests that some tracking methods used in the sub-6-GHz band, such as least mean squares (LMS), recursive least squares (RLS), and Kalman filter, are unsuitable for the mmWave band (due to higher frequency and shorter coherence time), and it recommends faster tracking strategies.