COFDM: an overview

The research and development of OFDM/COFDM for digital television broadcasting has received considerable attention and has made a great deal of progress in Europe. OFDM/COFDM has already been implemented in digital audio broadcasting and is being considered for terrestrial digital television and HDTV broadcasting. The advantages of COFDM claimed by the advocates in Europe have also caught the attention of US broadcasters and generated enthusiasm although a digital modulation technique called 8-VSB has been selected by the FCC Advisory Committee on Advanced Television Service (ACATS) for the final testing. There is considerable debate in the industry over the use of COFDM vs. VSB or QAM for terrestrial HDTV broadcasting. In this paper, the history of research and development on OFDM and COFDM is reviewed. Then, the basic principles, performance and implementation of OFDM and COFDM are examined. Analysis is given to enable the selection of key elements for meeting the constraints of the required applications. Based on the ATV channel model, performance expectation of COFDM under imperfect channel conditions and implementation issues are examined in details