Issue link: https://read.uberflip.com/i/1423190
LoRa Alliance ® Whitepaper Page 22 of 49 LoRaWAN ® Gateways Radio Coexistence Issues and Solutions Copyright ©2021 LoRa Alliance, Inc. All rights reserved. www.lora-alliance.org The required vertical isolation is therefore: Frequency Offset from UTRA DL Band Required Isolation for Wide-area BS (48dBm) Required Isolation for Medium-range BS (38dBm) 0MHz 97dB 87dB 2MHz 90dB 80dB 5MHz 67dB 57dB 7.5MHz 47dB 37dB 10MHz 32dB 22dB 20MHz 12dB 2dB According to Figure 11, the corresponding distance between the LTE BS antenna and the LoRaWAN gateway antenna is therefore: Frequency Offset from UTRA DL Band Min. Vertical Separation for Wide-area BS (48dBm) Min. Vertical Separation for Medium-range BS (38dBm) Min. Horizontal Separation for Wide-area BS (48dBm) Min. Horizontal Separation for Medium-range BS (38dBm) 0MHz 200m 70m >10Km >10km 2MHz 100m 30m >10km 6km 5MHz 7m 2.5m 1500m 400m 7.5MHz 1m 1m 150m 40m 10MHz 1m 1m 25m 7m 20MHz 1m 1m 2.5m 1m The separation distance may be mitigated, as line of sight is never obtained in real situations. However, a guard band less than 5MHz may cause a desensitization issue at the edge of the LTE DL band. It is then preferable to use LoRaWAN channels far out of the LTE DL band. The above tables show that a 45dB isolation between the LTE antenna and LoRa antenna is a good trade-off. This isolation can be achieved with minimum vertical separation (1m or 2m) and acceptable horizontal separation (150m maximum). This isolation also ensures no sensitivity degradation of the LoRaWAN gateway by the LTE BS when the band guard is greater than 5MHz. We can then consider the 45dB antenna isolation as a minimum requirement and a good assumption to define the LoRaWAN gateway's requirements. Assuming 45dB isolation also means that the maximum LTE BS power at the gateway RF port is 48dBm - 45dB = +3dBm. An example is provided here, considering a colocated LoRaWAN gateway with a CDMA 800 base station in India. The CDMA band edge is 869MHz, whereas the LoRaWAN band is 865 – 867MHz. A cavity filter is used to reject the CDMA DL band, and we can measure the noise generated by the CDMA 800 BS at the LoRaWAN gateway input.