What does the author mean with "Command Node" in the research paper?

I’ve been reading this research paper about a lightweight network protocol the author proposed to fix the privacy and security issues of smart homes. He mentioned “Command Node” multiple times and it’s still not clear to me what this is. I know what an IoT device is and a gateway (a router as example), but I still can’t figure out what the author means by “Command Node”.
What I was thinking is that this is an IoT device (like a cellphone or laptop) that executes a command, for example to turn on the lights, but im not sure… I can’t think of anything else.