Apparatuses and methods for generating an apsk signal

The invention relates to a transmitter communication apparatus (101) for communicating with a receiver communication apparatus (131) via a communication channel. The transmitter communication apparatus (101) comprises: a processing unit (105) configured to generate a stream of modulation symbols and map the modulation symbols to a digital signal constellation for generating a modulated signal, wherein the digital signal constellation comprises a plurality of digital signal points regularly spaced on at least two concentric circles having respective predetermined radii, wherein each circle has the same number of digital signal points and the digital signal points on each circle have the same phase with respect to the digital signal points on the other circles; and a communication interface (103) configured to transmit the modulated signal via the communication channel to the receiver communication apparatus (131). The invention also relates to a corresponding receiver apparatus (131) comprising a processing unit (135) and a communication interface (133) for communicating with the transmitter communication apparatus (101).