Blind phase noise mitigation for a 72 GHz millimeter wave system

Operating at higher frequencies, and in particular the millimeter wave (mmWave) frequency of 72 GHz poses various challenges to the RF hardware. One of these particular RF challenges is the phase noise (PN) created by the local oscillators (LOs) which is made worse by upbanding (i.e., multiplication by some factor) the LO to reach the desired frequency. The result of this relatively large PN is that in block-processing systems such as frequency-domain equalization for single carrier, there will be an unknown phase value which changes from block to block. Thus even if the channel itself does not change from one block to another, there would be one unknown phase value which needs to be tracked. In this paper we explore existing and propose new blind methods for tracking the PN in a null cyclic prefix single-carrier communication system. The methods are designed for BPSK and QAM constellations and are seen in simulations to have better performance than pilot-assisted tracking.