When I flashed my WRT3200ACM with a new firmware compiled to up-to-date master, I noticed that there is now a third radio in wifi config. Originally named as "mlan0".
That is due to these commits that created a new kernel module kmod-mwifiex-sdio and enabled it by default in WRT3200ACM:
https://github.com/lede-project/source/commit/6674aa97981001c7a96e629146b28be518165211
https://github.com/lede-project/source/commit/fb436f49ad5cff8836109159b2b6a2b4212d4700
Based on links found in the net, it sounds like a third radio interface, possibly with an internal antenna? Possibly also supporting Bluetooth?
https://eko.one.pl/forum/viewtopic.php?id=15254
https://github.com/Chadster766/McDebian
@Heinz
As you added those commits, could you please enlighten me about the practical usage of the new radio. Is it usable? Did you get bluetooth working?