An overview of the 5G New Radio (NR) physical downlink control channel (PDCCH) design of 3GPP Release 15 is presented and performance enhancements are proposed. A novel PDCCH hash function is shown to outperform the legacy hash function by about one order of magnitude in terms of inter-user blocking probability while maintaining the frequency-selective scheduling capability for downlink control information. Enhanced PDCCH candidate overbooking and mapping/dropping algorithms are investigated. Link level performance results of NR PDCCH with precoder cycling transmit diversity are presented for various aggregation levels and physical resource configuration options.

5G NR Physical Downlink Control Channel: Design, Performance and Enhancements