COFDM

Coded Orthogonal Frequency Division Multiplexing (COFDM) [1, 2] has been specified for digital broadcasting systems for both audio -- Digital Audio Broadcasting (DAB) [3] and (terrestrial) television -- Digital Video Broadcasting (DVB-T) [4, 5, 6]. COFDM is particularly well matched to these applications, since it is very tolerant of the effects of multipath (provided a suitable guard interval is used). Indeed, it is not limited to 'natural' multipath as it can also be used in so-called Single-Frequency Networks (SFNs) in which all transmitters radiate the same signal on the same frequency. A receiver may thus receive signals from several transmitters, normally with different delays and thus forming a kind of 'unnatural' additional multipath. Provided the range of delays of the multipath (natural or 'unnatural') does not exceed the designed tolerance of the system (slightly greater than the guard interval) all the received-signal components contribute usefully.

J H Stott (BBC) Explaining some of the magic of COFDM 

(c) Real-Time Vision 2005