IIR array processing based fast adaptive null steering algorithm using shift-invariant subarrays

This paper presents and investigates a fast adaptive null steering system employing infinite impulse response (IIR) array processing. The new algorithm is of considerable interest in communications where the desired signal is weak compared with the interfering signals or where the desired signal can be easily separated out. With the proposed algorithm, the nulls of the array system are repetitively updated one by one in a cyclical manner through a sequence of adjustment cycles. In each adjustment cycle, a particular null is updated by using the least mean square (LMS) algorithm and the update of each particular null will not affect other null positions. The proposed method is very effective and useful in the sense that it will result in a nearly flat gain in the antenna pattern, except zero gains at the null directions. Moreover, as will be demonstrated later from both analysis and simulation results, the convergence behavior of the new algorithm is significantly faster than the linearly constrained minimum variance (LCMV) method and is almost independent of the external noise environment.

► We present a fast adaptive null steering system employing IIR array processing.
► It has nearly flat gain in array pattern, except zero gains at null directions.
► Implementation complexity is comparable to that of LMS based LCMV method.
► Convergence behavior is significantly faster than that of LMS based LCMV method.