Remote interference management in 5G new radio: methods and performance

Elena Peralta,Toni Levanen,Mikko Valkama,Sari Nielsen,Youngsoo Yuk,Mikko Mäenpää,Klaus Pedersen

doi:10.1186/s13638-021-01926-2

Abstract

In time division duplexing based mobile networks, under certain atmospheric ducting conditions, the uplink reception may be interfered by the downlink transmissions of remote base-stations (gNBs) located hundreds of kilometers away. This paper addresses such remote interference problem in a 5G new radio (NR) macro deployment context. Specifically, two potential reference signal (RS) designs for remote interference management (RIM) are described. The first signal structure, denoted as the one OFDM symbol (1OS) based RIM-RS, is building on the channel state information reference signals of 5G NR. The second candidate is referred to as the two OFDM symbol based RIM-RS design, which builds on the design principles of LTE RIM-RS. The achievable detection performance is evaluated by introducing enhanced receiver algorithms together with three feasible propagation delay based gNB grouping and corresponding RIM-RS transmissions schemes. The performance results in terms of the receiver processing gain highlight that the improved detection algorithm assures sufficient performance to detect the remote interference for both RIM-RSs with all evaluated frequency domain comb-like patterns. The benefit of grouping corresponding RIM-RS transmissions from gNBs located on the same area is greater when using same frequency domain resources per transmitted sequence in practical interference scenarios. Furthermore, applying a common base sequence for all gNBs within a group allows to identify the group based on detected sequence and enables adaptive RIM mitigation schemes. On the other hand, it is shown that the 1OS RIM-RS provides smaller overhead and can be frequency multiplexed with the physical downlink shared channel, which opens up the possibility of using gNB group wise 1OS RIM-RS also for UE interference measurements.

Highlights

1.1 Background and basicsThe large number of base stations envisioned for the dense deployment of the fifth generation new radio (5G NR) mobile networks [1, 2] motivates the development of efficient remote interference management (RIM) schemes
An additive white Gaussian noise (AWGN) channel model with random phase rotation is assumed as a baseline to evaluate the detection performance of different 5G NR RIM-reference signal (RS) transmission schemes [10]
We extend the analysis by including a tapped-delay-line (TDL-E) fading channel model [19], which models a line-of-sight channel with first tap following Ricean distribution with a K-factor of K = 22 dB and a root-mean-squared delay spread of 30 ns

Summary

Introduction

1.1 Background and basicsThe large number of base stations envisioned for the dense deployment of the fifth generation new radio (5G NR) mobile networks [1, 2] motivates the development of efficient remote interference management (RIM) schemes. The so-called atmospheric ducting phenomena can impact the signal-to-interference-and-noise ratio in the uplink (UL) reception of a 5G NR base station (called gNB) by the downlink (DL) transmissions from a remote gNB. In [9], an increased RI level in Korea’s LTE-TDD system was shown due to Japan’s WiMax gNB from a distance of 240km, especially in cell radius of 0.5 km compared to smaller cells. In this practical study, it was observed that the path loss between both gNBs is about 142 dB when the height of both antennas is 30 meters—a path loss value lower than the free space propagation loss with the same distance

Methods

Results

Conclusion