LoRaWAN® Gateways: Radio Coexistence Issues and Solutions

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LoRa Alliance ® Whitepaper Page 4 of 49 LoRaWAN ® Gateways Radio Coexistence Issues and Solutions Copyright ©2021 LoRa Alliance, Inc. All rights reserved. www.lora-alliance.org 2 FUNDAMENTALS OF INTERFERENCE 2.1 RECEIVER DESENSITIZATION BASICS Going back to radio basics, a radio receiver requires the wanted received signal to have an amplitude that is a minimum number of dB above the noise floor, often expressed in terms of signal-to-noise ratio (SNR). Figure 2: Signal-to-noise ratio (SNR) Receiver sensitivity and SNR are important points of background information when considering RF interference. Desensitization of a receiver is generally defined as an additive noise phenomenon which degrades the receiver sensitivity or SNR, measured in dB. A receiver could be desensitized in different ways: • Out-of-band blockers • In-band blockers (co-channel, adjacent channels, etc.) • In-band spurious emissions • Intermodulation distortion (IMD) These phenomena are detailed in the following sections. 2.2 OUT-OF-BAND BLOCKERS Out-of-band blockers provide strong interference outside the useful band, causing saturation of the receiver. The consequence of this saturation is a degradation of the SNR, leading to desensitization. High-power blockers obviously generate more saturation and therefore more desensitization. Figure 3: Receiver out-of-band blocking and desensitization

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