No they did not patent OFDM, the patented the combination of an OFDM encoding schema and forward ECC, which, in combination allowed effective data transmission

No they did not patent OFDM, the patented the combination of an OFDM encoding schema and forward ECC, which, in combination allowed effective data transmission in a highly reflective environment. Everything the patent was based on was already known. Patents like this are not for inventing something new but combining some existing things to allow something new.