A Stack algorithm with limited tree-search

Due to the capacity achievable, Multiple-Input Multiple-Output (MIMO) systems witnessed more interest in recent years. Several data detection algorithms are available for MIMO systems, especially the tree-search ones which offer lower complexity comparing to the ML receiver. In this paper, we are interested in one of tree-search algorithms, which is the Stack decoder. Nevertheless, the stack decoder is only proposed to decode MIMO systems employing finite constellations, as the QAM (Quadrature Amplitude Modulation). In this work, we introduce a new Stack decoder capable of decoding lattice and we call it the M-Stack decoder. The principle idea behind it is to generate M nodes at each tree-level and so to reduce the infinite alphabet of the lattice to only M components at each step. Then, we propose to adapt it to decode QAM constellations. This one is compared to the known QRD-Stack algorithm. While both visit the same number of nodes, the proposed M-Stack algorithm offers lower computational complexity and it is much faster than the QRD-Stack one.