Patent ID: 6021334
Filing Date: 2000-02-01
Classification: H04B

Abstract:
Method for transmitting a digital signal composed of successive frames of samples, by a base station equipped with a multi-element antenna to a specific mobile, in the presence of interference sources and background noise, with the aid of at least one reception carrier frequency and at least one transmission carrier frequency, according to which:prior to sending:(a) for each reception carrier frequency, a reception calibration table is developed, representing the variation in contribution, as a function of the reception direction, of the various reception elements at the said reception carrier frequency;(b) for each transmission carrier frequency, a transmission calibration table is developed, representing the variation in contribution, as a function of the transmission direction, of the various transmission elements at the said transmission carrier frequency;(c) at least one frequency transposition operator is calculated which approximately transforms one said reception calibration table into one said transmission or reception calibration table;then, during sending:(d) statistical data are calculated on the basis of a plurality of samples of a plurality of frames of the signals received by the various elements, originating from the mobile and the interference sources;(e) for the said mobile, an optimum set of spatial weightings is calculated on the basis of the said statistical data, the said frequency transposition operator or operators, and a criterion for reinforcing the useful signal and reducing the interference sources;(f) the contributions to the said digital signal to be transmitted by each element are respectively weighted by the weightings obtained on the basis of the spatial weightings of the said optimum set; and(g) the said digital signal thus weighted is transmitted.