“…As the compression matrix is sparse according to the assumptions given in Section 2, the optimization problem involving Φ ∈ C N ×6 M turns out to be a non‐convex problem which is generally intractable (NP‐Hard). To handle this problem, motivated by [
29, 30], we build up the relationship between the sparse compression matrix topology and the compressive coefficients. Without loss of generality, we use the notation
to denote the compression matrix.…”