5G NR Uplink Coverage Enhancement Based on DMRS Bundling and Multi-slot Transmission

With the deployment of fifth-generation base stations, the improvement of cell edge coverage has become an important issue that needs to be solved. Compared with the downlink coverage, the uplink coverage limitation is more serious. Through the simulation analysis of the coverage performance of physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), and physical random access channel (PRACH), it is found that the coverage of PUSCH is the most severely restricted. This article analyzes the impact of the demodulation reference signal (DMRS) density and uplink waveform on PUSCH coverage. We find that adding DMRS in the same slot can improve the performance of channel estimation. Specifically, we propose to use DMRS bundling with the same or coherent DMRS being sent in multiple time slots for coverage enhancement. The receiver performs joint channel estimation on the DMRS in multiple time slots to improve the accuracy of channel estimation and enhance the coverage. Besides, a multi-slot repetitive transmission scheme is proposed, where the same data is repeatedly transmitted in multiple slots. Joint channel estimation and independent channel estimation are performed for this scheme separately. Our simulation results show that the proposed schemes can improve the coverage effectively.