Abstract: A method for optimizing a bit-to-symbol mapping operation. The method has steps of (a) determining a most probable symbol selection error made during a space-time decoding operation; and (b) selecting a bits-to-symbol mapper such that a bit-to-symbol mapping step results in a most probable symbol selection error, made during a space-time decoding operation, causes a minimal number of bit errors. The bits-to-symbol mapping step can be carried out so as to minimize an average number of bit errors resulting from an occurrence of the most probable symbol selection error, as well as from an occurrence of at least a second most probable symbol selection error, during the space-time decoding operation. A space-time coded communications system that operates in accordance with the method is also disclosed.

Abstract: A method is disclosed to minimize the mean-square-error of an estimate of an unknown parameter, such as a data symbol transmitted through a channel, such as a WCDMA channel. The method includes steps of (a) replacing a required multiplication of an input signal vector by an inverse covariance matrix, which is one of a total signal covariance matrix or an interference-plus-noise covariance matrix, by linear filtering, wherein directly computed or estimated filter elements of a row or a column of the inverse covariance matrix, corresponding to time instant i, are used as linear filter coefficients; (b) forming a vector g(i) from the filter outputs, the vector g(i) being estimated element by element using the linear filter; and (c) using the vector g(i) in place of a vector that would have been obtained by directly multiplying the signal vector by the inverse covariance matrix. The linear filter w(i) converges or closely converges to a row or column of the required inverse covariance matrix.