Modified Wiener beamforming for indoor channel improvement

The impulse response of an indoor channel varies with different environments and spatial positions of a transceiver pair as a function of the phase relationship among individual multipath components that have variety of time delays. This factor results in various fading especially in a chip duration of the direct sequence code division multiple access (DS-CDMA) system. To solve this problem, a modified Wiener beamforming (MWB) has been proposed to co-phase the multipath components and then combine them by maximum ratio combining in a chip duration. We derive formulas for MWB with a method to separate and estimate multipath vectors through each chip. Our purpose is to isolate and recombine multipath components before they are added together as a phasor to produce fading. Therefore, the fading of Rayleigh or Rice distributed multipath in a chip duration can be reduced to a minimum. Simulation results are presented by using a three-dimensional ray tracing to support the proposed method