Depth-First Spherical Lattice Space-Time Decoder with Boundary Control

Depth-first stack-based sequential decoder for spherical LAST codes with boundary control

A stack-based sequential depth-first decoder that returns Maximum-Likelihood solutions to spherical LAST coded MIMO system-type problems, i.e., a lattice decoder with spherical boundary control. In such problems, the depth of the search tree is known but the number of children per node is not fixed. The number of children and their associated symbol decisions are governed by the structure of the spherical LAST code. SEAL_det enforces boundary control by decomposing the code generator matrix in a manner that is like a dual to the standard sequential decoding procedure itself.

Note that inputs to SEAL_det must be real. The depth-first search is effected by applying the Schnorr-Euchner (Adaptive radius) enumeration to traverse the nodes of the tree. Exclusive of spherical boundary control, its operation is identical to that of a sphere decoder based on this enumeration.

Please see the function pre-amble (type `help SEAL_det` at the Matlab prompt) for more details.