Two-stage interference-resistant adaptive periodically time-varying CMA blind equalization

In this paper, we consider the problem of blindly equalizing a digital communication signal distorted by a linear time-invariant channel and contaminated by severe co-channel or adjacent-channel digital interference under the assumption that the latter exhibits a different symbol rate from the desired signal. The proposed equalizer is composed of two stages that are both periodically time-varying (PTV) in order to better match the periodical statistics of the received signal. The first stage employs linear PTV filtering to mitigate interference, thus allowing the second stage, based on the constant modulus algorithm (CMA), to reliably recover the transmitted information symbols. Computer simulations confirm the effectiveness of the new approach, and comparisons with existing blind methods show that a significant performance gain can be attained.