Reference Signal Design for Remote Interference Management in 5G New Radio

In 5G new radio (NR) networks with macro deployment scenarios, downlink transmissions from one remote base station, e.g located hundreds of kilometers away, may interfere the uplink reception of a victim base station under certain atmospheric ducting conditions. This paper addresses two potential reference signal designs (RS) for remote interference management (RIM) based on the latest 3GPP Release 16 specifications. Exact RS requirements for the 5G NR networks are still under discussion as part of the work item phase. Therefore, to comprehensively evaluate the most suitable RIM-RS designs, first, we evaluate one-symbol (1OS) RS structure based on the existing channel-state-information reference signal (CSI-RS). Secondly, a new RS is examined based on the baseband signal generation for the physical random access channel (PRACH), where two copies (2OS) of the RS sequence are concatenated and one cyclic prefix (CP) is attached at the beginning. In both cases, a symbollevel detector algorithm is adopted exploiting the RSs repetition structure in time domain. The results indicate that the number of detection windows in addition to the RS sequence length and symbol duration have a high impact in the detection performance. In general, both RS designs can be detected up to 500 km distance and these results suggest that 1OS RS can be considered as a potential NR RIM-RS candidate using less resources and allowing RIM-RS to be time and frequency multiplexed within PDSCH data. Besides, in real deployment scenarios, the 1OS RS could be more suitable than the 2OS RS when increasing the number of gNBs transmitting different sequences of the RIM-RS, due to the shorter time duration and lower overlap between sequences.