# On Spectral Coexistence of CP-OFDM and FB-MC Waveforms in 5G Networks

## TL;DR

This paper critically evaluates the spectral coexistence of CP-OFDM and FB-MC waveforms in 5G networks, revealing that FB-MC does not significantly improve coexistence as previously assumed, based on a comprehensive interference metric.

## Contribution

It challenges the assumption that FB-MC waveforms enhance coexistence with CP-OFDM by demonstrating the need for proper interference metrics and providing new insights into spectral compatibility.

## Key findings

- FB-MC waveforms do not significantly improve coexistence with CP-OFDM
- A proper interference metric is essential for accurate coexistence assessment
- Spectral localization alone is insufficient for coexistence evaluation

## Abstract

Future 5G networks will serve a variety of applications that will coexist on the same spectral band and geographical area, in an uncoordinated and asynchronous manner. It is widely accepted that using CP-OFDM, the waveform used by most current communication systems, will make it difficult to achieve this paradigm. Especially, CP-OFDM is not adapted for spectral coexistence because of its poor spectral localization. Therefore, it has been widely suggested to use filter bank based multi carrier (FB-MC) waveforms with enhanced spectral localization to replace CP-OFDM. Especially, FB-MC waveforms are expected to facilitate coexistence with legacy CP-OFDM based systems. However, this idea is based on the observation of the PSD of FB-MC waveforms only. In this paper, we demonstrate that this approach is flawed and show what metric should be used to rate interference between FB-MC and CP-OFDM systems. Finally, our results show that using FB-MC waveforms does not facilitate coexistence with CP-OFDM based systems to a high extent.