Phase Noise Limits in Low-Rate Communication via Satellite

In the Internet of Remote Things (IoRT), when satellite communication (SATCOM) is the preferred or the only available connection for Internet of Things (IoT)-devices, massive machine type communication (mMTC) is enabled by upcoming and established systems using sophisticated multiple access (MA) techniques. To close the radio link between compact and battery-powered devices, very low symbol rates must be chosen in many cases, due to the constraints of the link budget. If at the same time MA interference must be tolerated, orthogonal signaling with successive interference cancellation (SIC) receivers is usually the physical layer technology of choice in many IoT solutions. While SIC has been investigated for medium and high data rates, phase noise (PN) poses additional challenges for very low data rate transmission. We derive a general performance estimation applicable to SIC-based transmission schemes under PN with different levels of orthogonality between the user signals. Realistic values for the PN are derived from a PN model that includes all relevant PN processes and is parametrized by measurements of the Allan variance of real hardware. It is shown that PN strongly limits the performance of systems with high orthogonality at symbol rates below 1 kHz, while systems with less orthogonal transmit signals and lower spreading gain are more robust.