Signal modulation and demodulation for multiuser superposition transmission scheme

A method for a base station that is configured to operate under a multiuser superposition transmission (MUST) operation in a mobile communication network, comprising:

• generating a constellation map based on a first modulation having an order of 2n, a second modulation having an order of 2m, and a power split factor, m and n being positive integers,
• the constellation map including 2m+n constellation points, and
• the constellation points including 2n first groups of 2m constellation points, the 2n first groups being positioned based on the first modulation and the power split factor, and the 2m constellation points within each first group being positioned based on the second modulation and the power split factor;
• assigning, by a processor of the base station, a bit sequence for each constellation point on the constellation map,
• each bit sequence including n bits assigned for a first terminal device in the mobile communication network concatenated with m bits assigned for a second terminal device in the mobile communication network,
• the constellation points being arranged into 2n second groups of constellation points according to clustering of the constellation points,
• each second group including 2m constellation points, being assigned a respective n-bit sequence for the first terminal device, and overlapping two or more of the 2n first groups, and
• each of the 2m constellation points within a particular second group being assigned a respective m-bit sequence for the second terminal device;
• modulating and outputting, by the processor of the base station using the first modulation and the second modulation, a superposed signal corresponding to a particular constellation point that represents a particular bit sequence based on the assigned bit sequences;
• and
• transmitting the superposed signal to the mobile communication network.