Transmission scheme for a K-way relay multiple-input multiple-output channel

In the multiple-input multiple-output Gaussian K-users relay interference channel, each user intends to convey a multicast message to all the other users while receiving K-1 independent messages from the other users via an intermediate relay. An encoding and decoding strategy is proposed which is inspired from cryptography theory. The proposed encoding and decoding strategy involves a signal space alignment for an encryption message for multiple access phases and zero forcing with successive network code decoding for the broadcast phase. Then, the investigation of the antenna configuration conditions is an initial step for addressing the degrees of freedom of the above channel. It presents a new modified high-order pulse amplitude modulation that enables us to use the computationally efficient binary channel coding under a physical-layer network coding. It is shown that the proposed signalling scheme significantly outperforms the conventional non-binary code and is slightly worse than the lattice code.