A New Algorithm for Improved Blind Detection of Polar Coded PDCCH in 5G New Radio

Abstract: In recent release of the new cellular standard known as 5G New Radio (5G-NR), the physical downlink control channel (PDCCH) has adopted polar codes for error protection. Similar to 4G-LTE, each active user equipment (UE) must blindly detect its own PDCCH in the downlink search space. This work investigates new ways to improve the accuracy of PDCCH blind detection in 5G-NR. We develop a novel design of joint detection and decoding receiver for 5G multiple-input multiple-output (MIMO) transceivers. We aim to achieve robustness against practical obstacles including channel state information (CSI) errors, noise, co-channel interferences, and pilot contamination. To optimize the overall receiver performance in PDCCH blind detection, we incorporate the polar code information during the signal detection stage by relaxing and transforming the Galois field code constraints into the complex signal field. Specifically, we develop a novel joint linear programming (LP) formulation that takes into consideration the transformed polar code constraints. Our proposed joint LP formulation can also be integrated with polar decoders to deliver superior receiver performance at low cost. We further introduce a metric that can be used to eliminate most of wrong PDCCH candidates to improve the computational efficiency of PDCCH blind detection for 5G-NR.