A digital communication system and a receiver for use in such a system

Known in a digital communication system (1) are phase recovery methods for QPSK modulated signals. It is proposed to extend such methods to multi-resolution QAM signals, which can be represented by rotationally invariant signal constellations. To this end, with each received symbol (ri), a phase reference ( phi i) for a high priority-bit (HP-bits) constellation is determined, and with respect to this phase reference ( phi i), a sub-constellation (CLx) for low-priority bits (LP-bits) is constructed, the sub-constellation (CLx) being rotationally invariant. The sub-configuration (CLx) is translated to an origin (O) of the signal constellation, and then the low priority-bits (LP-bits) are determined by determining a minimum squared Euclidean distance (Ed) of the rotated and translated received symbol (bi') with respect to the rotated and translated sub-constellation. For a 2R(2,2)-QAM signal constellation a simple detection method is thus provided. The method can be made adaptive, and can also be made recursive for more complicated signal constellations such as a 64-QAM signal constellation.