LoRaWAN® Gateways: Radio Coexistence Issues and Solutions

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LoRa Alliance ® Whitepaper Page 25 of 49 LoRaWAN ® Gateways Radio Coexistence Issues and Solutions Copyright ©2021 LoRa Alliance, Inc. All rights reserved. www.lora-alliance.org Depending on the noise performance of the gateway, the gateway manufacturer has basically two options: • Use a cavity filter (external or internal) to attenuate the out-of-band noise in the LTE BS UL band. • Increase isolation between the LTE and LoRa antennas, according to the following vertical and horizontal separation distance: Noise in LTE UL Band Required Isolation Min. Vertical Separation Min. Horizontal Separation -70dBm/100KHz 54dB 2m 300m -75dBm/100KHz 49dB 1m 150m -80dBm/100KHz 44dB 1m 90m -85dBm/100KHz 39dB 1m 50m -124dBm/100KHz 0dB 1m 1m The vertical and horizontal separation distance is evaluated according to Figure 11. 3.6 INTERMODULATION OF LTE EMITTERS An LTE BS signal is an OFDM signal based on QPSK, 16QAM, or 64QAM modulation. This modulation is a non-linear modulation; injecting the OFDM into signal in a non- linear receiver would cause generation of IM3 products, as explained in §2.4. When the LTE BS signal is injected into the LoRa receiver, IM3 (or even IM5) products may be generated, falling into the LoRaWAN band as shown here: LTE DL band LoRaWAN band Figure 23: Intermodulation of LTE BS signal in LoRa receiver

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