Effects of desired signal on the performance of a sidelobe canceller

The performance of a sidelobe canceller is studied in a communication system where the desired signal is continually present and its amplitude in the auxiliary antennas may be large (above thermal noise). In such a system to avoid the cancellation of the desired signal, one can use a reference signal and adjust the auxiliary antenna weights to minimize the error between the reference signal and the sidelobe canceller output or one can use a steering vector. It is shown that in spite of the reference signal or a steering vector, the presence of the desired signal in the auxiliary antennas degrades the interference suppression provided by a sidelobe canceller. The amount of degradation depends on the number of degrees of freedom, the strength of the various signals, and the angular resolution of the auxiliary antenna array. Signal scenarios involving a single interfering signal as well as those involving multiple interfering signals are considered