Correlation based doubly adaptive array for CDMA uplink signal communication

Many 900 MHz cellular telephone propagation experiments show multipath induced rms delay spreads with 2 to 3 ps being typical in urban areas and continuous multipath power out to 5 μs. The doubly-adaptive-array (DAA) technique described herein is designed to provide coherent integration over a continuous delay window of arbitrary size and thereby minimize uplink IS-95 code-division-multiple-access (CDMA) demodulation errors. Multiple user interfering signals are ed by conventional digital techniques after the array space has been transformed by eigenvector multiplication into orthogonal beam space. A scheme for computing two sets of array beamforming weights in closed form is the key to the successful implementation of this array processing technique. Many downlink beamforming techniques are based on uplink RF angle-of-arrival (AOA) measurements, therefore one of the DAA outputs can be used to compute measured array steering vectors that are then inserted into a direction finding processor.