Optimisation of convergence of sequential decorrelator

Claim 1

A sequential decorrelator arrangement for an adaptive antenna array comprising a plurality of antenna elements the outputs of which feed a cascaded beamforming network having a succession of stages, each stage including a group of signal decorrelation cells, the group in each stage having one less cell than the group of the preceding stage and the first stage group having one less cell than the number of antenna elements, each cell of the first stage having as one input the output of a respective antenna element and as a second input the output of the remaining antenna element to produce an output signal and each cell of each subsequent stage having as one input the output of a respective cell of the preceding stage and as a second input the output from the remaining cell of the preceding stage to produce an output signal, the whole arrangement including means for applying weighting to the signals applied as inputs to the cells of at least the first stage, characterised in that the decorrelation cells in each stage comprise means for applying simple transforms to the input data in accordance with a weighting factor common to all the cells in a stage, each stage further including means for deriving said weighting factor from the weighting factor deriving means of the previous stage and the output of one cell of the preceding stage, and each stage including means for scaling the output of each cell in the stage by a scaling factor calculated from the weighting factor deriving means of the stage.

Claim 3

A method of sequentially decorrelating by the least squares QR processing algorithm signals received from an antenna array using cascaded stages of decorrelation cells in which each cell decorrelates the outputs of two cells of the preceding stage by applying rotational transforms thereto in accordance with a weighting factor common to all the cells in a stage, the weighting factor for each stage being derived from the weighting factor of the preceding stage modified by the output of one cell of said preceding stage, characterised in that the method includes the application of scaling factors for scaling the output of each cell in a stage, said scaling factor being calculated from the weighting factor for the stage.

Claim 4

A method of sequentially decorrelating by the least squares QR processing algorithm signals received from an antenna array using cascaded stages of decorrelation cells in which each cell decorrelates the outputs of two cells of the preceding stage by applying rotational transforms thereto in accordance with a weighting factor common to all the cells in a stage, the weighting factor for each stage being derived from the weighting factor of the preceding stage modified by the output of one cell of said preceding stage, characterised in that the method includes the application of scaling factors for scaling the output of each cell in a stage, said scaling factor being calculated from the weighting factor for the stage.