MIMO transmission method for discrete modulated signals

A Multiple Input Multiple Output (MIMO) transmission method for discrete modulated signals, and a MIMO transmission model for the discrete modulated signals is y=HGΔx+n, where x is source multi-dimensional vectors of initial multi-channel Amplitude Shift Key (ASK) constellation diagram symbols, y is received signals of each channel obtained by a receiver, H is a known channel matrix, G is a precoding matrix of MIMO, and Δ is a constellation expansion factor;

• the method comprises the following steps:
• (S1) initializing the precoding matrix G;
• (S2) for any value of the constellation expansion factor Δ, maximizing a source entropy H(x) by adjusting a source distribution Px of the source multi-dimensional vectors x, and selecting the constellation expansion factor Δ and the source distribution Px for maximizing a mutual information I(x;y)=H(x)−H(x|y) according to the current precoding matrix G, where H(x|y) is a conditional entropy;
• (S3) according to the current constellation expansion factor Δ and the source distribution Px, adjusting the precoding matrix G by a gradient descent method to further maximize the mutual information I(x;y);
• (S4) determining whether the values of the current constellation expansion factor Δ, the source distribution Px and the precoding matrix G converge, and if the values do not converge, performing step (S2);
• and
• (S5) obtaining a marginal distribution of the symbols of each channel in the source multi-dimensional vectors X according to the distribution of the source multi-dimensional vectors x, and performing a non-uniform modulation on the signals of each channel by a single-channel probabilistic amplitude shaping technology.