ABSTRACT
The state of coded orthogonal frequency division multiplex (COFDM) development reported by the Task Force varies from laboratory-to-laboratory in Europe. Much of the difference results from different purposes or emphases for which the COFDM systems are being developed. In each case, there is a large number of closely spaced carriers, but the modulation levels applied varied considerably. Some aspects of COFDM systems have not yet been fully addressed by the European laboratories because of where they are in the development process. Techniques proposed range from various sync symbols sent with the data to separate pilot carriers for both local oscillator locking and clock recovery. The Task Force identified a number of areas of concern regarding the COFDM approach. The Task Force found no benefit to cable operations from COFDM. With single-carrier systems, cable implementations might be able to double channel capacity by trading off against carrier-to-noise ratio.
