You state that all devices are within 1km. I have found LoRaWAN is viable alternative to costly runs of conduit (which cost kills many data-collection projects) and my facility is large, with many metal-sheeting partition walls, reinforced concrete, etc. Even so, all my sensors uplinks are received by all gateways, just with different SNR/RSSI; so much so that I disabled some of the installed gateways (red dots) 
Example of one sensor’s uplink:
gatewayID:“*************7bc6”
* rssi:-105
* loRaSNR:-1.5
gatewayID:“**********474b”
* rssi:-106
* loRaSNR:-2.8
gatewayID:“***********3935”
* rssi:-72
* loRaSNR:12.2
gatewayID:“***********3da3”
* rssi:-75
* loRaSNR:12.8
Given particular sensor shown is in the “top” part of facility, you can deduce which gateways are which