Transmitter device and receiver device for a wireless communication system

A receiver device for a wireless communication system, the receiver device comprising:

• processing circuitry configured to:
• obtain an aggregated matrix in an intermediate-frequency domain for a plurality of users based on a signal received in a time domain from a transmitter device, the aggregated matrix in the intermediate-frequency domain having a form of M×N, M being a number of rows, where M>1, and N being a number of columns, where N≥1;
• obtain a plurality of first data symbol matrices in the intermediate-frequency domain for the plurality of users by deconcatenating the N columns of the aggregated matrix in the intermediate-frequency domain, each first data symbol matrix having a form of Mu×N, Mu being a number of rows specific to a user u of the plurality of users, wherein M is greater than a sum of the respective numbers of rows Mu of the plurality of first data symbol matrices for the plurality of users;
• and
• obtain a plurality of second data symbol matrices in a delay-Doppler domain for the plurality of users by performing, for each user u of the plurality of users, a Mu-point Inverse Fast Fourier Transform (IFFT) operation on the first data symbol matrix of the user u, the obtained second data symbol matrix of the user u having the form of Mu×N.

A method for a transmitter device, the method comprising:

• obtaining a plurality of first data symbol matrices in a delay-Doppler domain for a plurality of users by arranging, for each user u of the plurality of users, data symbols of the user u in a first data symbol matrix having a form of Mu×N, Mu being a number of rows specific to the user u, where Mu>1, and N being a number of columns, where N≥1;
• obtaining a plurality of second data symbol matrices in an intermediate-frequency domain for the plurality of users by performing, for each user u of the plurality of users, a Mu-point Fast Fourier Transform (FFT) operation on the first data symbol matrix of the user u, the obtained second data symbol matrix of the user u having the form of Mu×N;
• and
• obtaining an aggregated matrix in the intermediate-frequency domain for the plurality of users by concatenating the N columns of each of the plurality of second data symbol matrices in the intermediate-frequency domain, the aggregated matrix having a form of M×N, M being a number of rows, wherein M is greater than a sum of the respective numbers of rows Mu of the plurality of second data symbol matrices for the plurality of users.