(Note: This is a very rough draft just to jot things down before I forget.)
LEMA was the name of a Lithuanian country-wide IP radio network to provide Internet access to schools and other educational institutions in the 1990s and 2000s. (More accurately, it was the name of the company that had been contracted by LITNET to build the network.)
Over most of its lifetime, LEMA used 802.11b (2.4 GHz) Wi-Fi links in 'ahdemo' mode, which was somewhat similar to the standard 'ad-hoc' mode but without any beacons – effectively like "Ethernet over radio". From what I know, the network was mostly based on static routing, though it seems OSPF may have been used in a later iteration.
The links were built out of off-the-shelf hardware: several grid antennae on the roof, with thick coaxial lines going into ORiNOCO (and similar) PCMCIA wireless cards of a gateway. The gateways were either standard desktop/tower PCs with Avaya PCI-to-PCMCIA adapter cards, or Soekris net4511 single-board computers (an early Raspberry Pi if you will).
One generation of the gateways (Pentium and Soekris) ran MS-DOS and custom LEMAbridge software which provided static IPv4 routing, port filtering, and even NAT. One of the interesting features was a custom hardware watchdog connected to the floppy drive port; the LEMAbridge software would issue a low-level read command every so often. (Soekris units had an internal SoC watchdog and didn't need this hack.)
A slightly later generation seems to have been based on Bifrost Linux.