th Asilomar Conference on Signals Systems & ComputersFundamentals of Coding for Broadcast OFDMRichard

The same information is often broadcast to many receivers over diierent frequency selective channels. Digital audio signals and digital video signals are commonly distributed by such broadcasts. A coded modulation technique for orthogonal frequency division mul-tiplexing (OFDM) is presented that provides consistent performance over a variety of frequency selective channels. The range of performance for an example of the new scheme over three diierent frequency selective channels is 0.75 dB at P e = 10 ?6 as compared to 4 dB for a commonly used scheme. The new technique employs relatively dense constellations combined with low rate codes designed to allow the receiver to take advantage of reliable symbols to compensate for unreliable symbols. Frequency hopped systems and at fading systems with inter-leaving can also beneet from the new technique.