Method and apparatus for suppressing interference from bandspread

Abstract

A method and apparatus are provided for suppressing interference from a sence of bandspread communication signals received by a radio receiver. Each sample is defined as a vector having signal and interference vector components. The interference vector component is such that: 1) the interference dominates the signal vector component, and 2) the phase of the interference vector components in the sequence changes slowly with time. Interference is suppressed while a portion of the signal vector component that is normal to the interference vector component is estimated as an indication of the bandspread communication signal. To do this, a phase angle is determined for each sample based upon each sample's defined vector. The phase angle for each sample is transformed into a corresponding phase vector based on a symmetric sampling of phase angles from previous and subsequent received signal samples. All terms of each corresponding phase vector are summed and averaged to generate a corresponding average phase gain for each sample. Each corresponding average phase gain is multiplied by a vector normal to the corresponding sample's defined vector to estimate the signal vector that is normal to the interference vector for each sample. The method and apparatus are effective whenever the phase of the interference vector components is characterized as having a frequency of change that is less than 1/2T, where T is the time required to receive the symmetric sampling.