Networking that doesn't use ethernet cables or Wi-Fi is always fascinating. I'm reminded of the way some labs in the pre-wifi days used infrared beacons and transceivers on laptops to create local wireless networks.
https://www-01.ibm.com/common/ssi/ShowDoc.wss?docURL=/common... or https://groups.csail.mit.edu/mac/ftpdir/thinkpad/old-archive...
only picture I could find of one: https://www.ebay.com/itm/0934340-IBM-INFRARED-WIRELESS-PCMCI...
Still you wouldnt be aiming whole computers with pcmcia cards in them, there was a dongle, most likely with a clip or velcro to slap in on the back of laptop screen.
The device in question was only available on appointment, so we only had a few shots at this.
Eventually we went with adding a checksum and resending the whole "packet" (one byte) when it didn't match, because we couldn't get the damn thing to send stuff correctly 100% of the time.