Multi-resolution 64-DAPSK modulation in a hierarchical COFDM transmission system

The two alternative modulation schemes of 64-QAM (quadrature amplitude modulation) and 64-DAPSK (differential amplitude and phase shift keying) with a coherent and incoherent demodulation have been proposed for digital terrestrial video broadcasting (DTVB) in combination with the Coded Orthogonal Frequency Division Multiplexing (COFDM) technique [2, 3]. Additionally, a hierarchical transmission system based on a multi-resolution (MR) 64-QAM is described in [2] which extends the service area of a TV programme in decoding a stepwise reduced data rate with an increasing transmitter distance (graceful degradation). This procedure corresponds with a decreasing of picture quality. In this paper MR concepts for the 64-DAPSK - which is rather new - are developed. A performance comparison between the hierarchical transmission systems (MR-64-QAM/OFDM and MR-64-DAPSK/OFDM) is described for the uncoded and coded case.