Mitigating interference challenges in integrated 5G New Radio and Narrowband Internet of Things networks

Abstract

This study focuses on mitigating Narrowband Interference (NBI) that results from Fifth Generation New Radio (5GNR) and Narrowband Internet-of-Things (NB-IoT) coexisting on the same spectrum. As NB-IoT reuses the same spectrum as the 5GNR, the coexistence of these two frequency bands results in an unwanted interference referred to as a Narrowband Interference (NBI). The main aim of the coexistence of these two bands is to enable frequency reuse which is important to maximise spectrum utilisation as spectrum is very scarce. This study describes 5GNR specifications and how devices and network infrastructure transmit/receive data to/from each other by the reuse of electromagnetic radio waves. As 5GNR uses some of the frequencies up to 6GHz of the spectrum, referred to as sub-6 spectrum, interference tends to occur because of the spectrum being occupied by other cellular radio technologies including but not limited to Machine-Type Communication (LTE-M), Long-Term Evolution (LTE) and NB-IoT. Although 5GNR has an advantage of using a technology called Dynamic Spectrum Sharing (DSS) which allows spectrum sharing as the LTE, LTE-M and NB-IoT, the challenge of reduced spectral efficiency, user and network performance still exists. The principal objective of this study is therefore to effectively analyse the coexistence of the 5GNR and NB-IoT and develop a protocol to reduce the current spectral efficiency limitation with the further aim of increasing overall user and network performance in a smart network. Firstly, analysis of the characteristics of 5GNR and NB-IoT was performed using MATLAB based on their bandwidth and modulation schemes and then which problem was addressed by experiments in MATLAB. The characteristics of these waves on the spectrum analyser were investigated. The frequencies used in 5GNR and NB-IoT were of the most importance as frequency and bandwidth have a relationship, and again the relationship of bandwidth and wavelength were among the considerations. Various modulation schemes were considered, and it was concluded that for this study, the highest order modulation scheme which is 256 Quadrature Amplitude Modulation (256QAM) be used as it is a better modulation scheme compared to other modulations schemes based on more information capacity than 64-QAM and 16-QAM and has 256 number of message points which is higher than the 64-QAM and 16-QAM. Among the key results of the study, it is shown that lower frequencies are required to be used to mitigate interference. Another advantage of using lower frequencies is that of having higher wavelength which are good for penetration of larger distances especially in South Africa where recently there are still not enough towers with 5GNR. From the results of the MATLAB experiments in this study it was concluded that lower frequencies are used in either of the two technologies coexisting on the same spectrum to mitigate interference. As 256QAM is the modulation scheme used for 5GNR, the interferer gain is kept as low as possible. The key result from this study is the improved Signal to Interference and Noise Ratio (SINR).