Impact of PDCCH Position on Air Interface Latency: For Dynamic Spectrum Sharing and uRLLC

Abstract

Since Physical Downlink Control Channel (PDCCH) is used to schedule Physical Uplink Shared Channel (PUSCH) or Physical Downlink Shared Channel (PDSCH), the change of PDCCH position will affect the air interface latency. In terms of manufacturers' implementation, the PDCCH is generally placed at the beginning of a slot. However, for Dynamic Spectrum Sharing (DSS) and uRLLC, PDCCH can be moved to other positions in the slot. In this paper, using probability density function (PDF), we discussed the impact of changing position of PDCCH on air interface latency, find the PDCCH position that causes maximal air interface latency, the mean value of which is calculated for every slot in a subframe. Comparing with the latency when the PDCCH is located at the beginning of the slot, we can obtain the maximum impact of PUCCH position on air interface latency for Frequency Division Duplex (FDD) and Time Division Duplex (TDD).