Generating a linear dispersion code for use in a MIMO system using a second matrix itself derived from a first matrix

摘要

A method of generating an LDC for use in a MIMO communication system in which M transmit antennas are used to transmit a codeword over T time slots, each codeword encoding Q constellation symbols. The invention involves generating a first matrix S2a (such as the external control matrix defined in equations 7 and 8 of p15) having 2Q columns and a predetermined number m of rows, each column comprising a plurality of elements, each element being a real number within a respective predefined range for the respective row. A second matrix S4a (such as the internal control matrix of equations 10 and 11 of p15) having 2Q columns and m rows is derived from the first matrix. Claim 1 requires that "the elements of one row of the second matrix are dependent upon the corresponding elements of the corresponding row of the first matrix and upon M and T". A set of 2Q LDC dispersion matrices, each of dimensions T x M is generated from the second matrix. Preferably this involves generating rotated unitary matrices from the second matrix S5a (equation 12), generating 2Q unitary matrices from the rotated unitary matrices S6a (equations 13 and 14) and extracting from each unitary matrix a corresponding LDC dispersion matrix by selecting elements of the unitary matrix using a dimension requirement based on the relative values of T and M (equations 17-19). An optimization procedure preferably involves generating a plurality of different LDCs and applying a cost-function to each.