Inter-Numerology Interference in 5G New Radio: Analysis and Bounds for Time-Varying Fading Channels

Mixed numerology is a new feature of the orthogonal frequency division multiplexing-based physical layer of 5G new radio (NR). It enables 5G to serve diverse use cases and services. However, the subcarriers of different numerologies, despite being non-overlapping in frequency, interfere with each other due to their different bandwidths and symbol durations. We derive novel expressions for the fading-averaged INI power at each subcarrier of a numerology in a wideband timevarying channel. These expressions cover the general family of numerologies of 5G NR, account for the guard band (which is used to mitigate INI), and apply to line-of-sight (LoS) and non-LoS channels. These lead to insightful expressions and tight bounds for the bandwidth-averaged INI power. They reveal that the INI power increases quadratically with the Doppler spread of the channel and affects higher-rate modulation and coding schemes.