Issue link: https://read.uberflip.com/i/1423190
LoRa Alliance ® Whitepaper Page 33 of 49 LoRaWAN ® Gateways Radio Coexistence Issues and Solutions Copyright ©2021 LoRa Alliance, Inc. All rights reserved. www.lora-alliance.org • Sensitivity = -140dBm, and we may allow maximum 3dB degradation • Co-channel rejection = 25dB • Adjacent channel rejection = 75dB • 2MHz offset rejection = 95dB Therefore, the required isolation, depending on the allowed EIRP, is: Required Isolation Co-channel Adjacent Channel +/- 200KHz +/- 2MHz In-band blocker rejection 25dB 75dB 95dB In-band blocker max. level (relative to -140dBm) -115dBm -65dBm -45dBm Gateway Tx EIRP = 16dBm 131dB 81dB 61dB Gateway Tx EIRP = 29dBm 144dB 94dB 74dB Gateway Tx EIRP = 36dBm 151dB 101dB 81dB The co-channel required isolation is very high, from 131dB to 151dB. This basically means that desensitization on the same channel is inevitable. The required isolation for adjacent channels, alternate channels, and up to 2MHz offset varies from 61dB to 101dB. The required isolation must be translated into distance separation. Two use cases are considered: vertical separation and horizontal separation. Vertical separation is obviously recommended, as we can benefit from the antenna pattern characteristic of the antenna. About 30dB isolation can be achieved with the vertical position for a 6dBi antenna gain, whereas no improvement can be achieved in the horizontal plane. High antenna gain (6dBi or more) is therefore highly recommended in the case of colocation of LPWAN gateways. In the following table, the distance is converted into isolation (dB) assuming direct line of sight (LoS). The frequency used for the calculations is 868MHz, but results would not be very different using 915MHz, for instance. Vertical separation: Vertical Antenna Separation (m) 1m 3m 6m 15m 30m 60m Antenna isolation (vertical) 30dB 30dB 30dB 30dB 30dB 30dB Antenna separation (LoS) 31dB 41dB 47dB 55dB 61dB 67dB Total isolation 61dB 71dB 77dB 85dB 91dB 97dB Horizontal separation: Horizontal Antenna Separation (m) 30m 50m 100m 300m 1000m 2000m Antenna isolation (horizontal) 0dB 0dB 0dB 0dB 0dB 0dB Antenna separation (LoS) 61dB 65dB 71dB 81dB 91dB 97dB Total isolation 61dB 65dB 71dB 81dB 91dB 97dB