Weighted autocorrelation method for downlink CDMA LMMSE equalizers

An article of manufacture comprising a program storage medium readable by a computer, the medium embodying instructions executable by the computer for performing actions for receiving a wireless code division multiple access signal, the actions comprising:

• receiving at least one received signal grouped in blocks of chips, the blocks being further grouped in slides, on at least one receive antenna;
• equalizing said received signal in a linear minimum mean squared error equalizer;
• updating said equalizer by estimating an auto-correlation matrix with a sample average of received signals over an update period and passing said auto-correlation matrix through a multidimensional matrix filter that weights older sample data less than recent sample data;
• and
• processing the output of said equalizer to generate said wireless code division multiple access signal.

A method of dynamically adjusting a filter in a receiver for changing channel conditions, comprising:

• receiving a first block of signals over at least one channel;
• estimating a first correlation matrix for the first block of signals once in an update period P1, said first correlation matrix correlating data from a total of n1 blocks of signals;
• equalizing the first block of signals using the first correlation matrix;
• receiving a second block of signals over the at least one channel;
• determining that a coherence interval between the second block of signals and a block of signals received immediately prior to the second block of signals is shorter than a coherence interval between the first block of signals and a block of signals received immediately prior to the first block of signals;
• estimating a second correlation matrix for the second block of received signals once in an update period P2, said second correlation matrix correlating data from a total of n2 blocks of data, where P2 is shorter than P1 and n2 is greater than n1;
• and
• equalizing the second block of signals using the second correlation matrix.