There are no single channel gateways - a gateway has at least 8 decoders. These are disruptive to TTN and to other users - please disconnect this “not a gateway”. See Single Channel Packet Forwarders (SCPF) are obsolete and not supported
Can’t comment on the research but OTAA can be single frequency.
Is there a reason you don’t have a full gateway? You could setup a Single Channel Hub which are OK for use on TTN.