It's a full AT stack software architecture, so everything runs on the host processor that is on the module itself; the AT commands are in the UART manager. There is an RTOS that runs on top of the drivers; this includes a file system with boot loaders, radio, UMAC, TCP/IP sockets, WPA supplicant, and the mini-access-point-related tasks. Everything runs on top of the STM32 and the lower MAC of the radio.