How is OFDM implemented in the real world?
OFDM is accomplished with digital signal processing (DSP). You can program the IFFT and FFT math functions on any fast PC, but it is usually done with a DSP IC or an appropriately programmed FPGA or some hardwired digital logic. With todays super-fast chips, even complex math routines like FFT are relatively easy to implement. In brief, you can put it all on a single chip.