Characteristics of band-limited channels unidentifiable from second-order cyclostationary statistics

Several works on blind channel identification and equalization rely on a system model with multiple sub-channels driven by a single input. These methods depend on a critical condition that no common zero exists among the sub-channels. We aimed at establishing the physical significance of this critical zero condition and understanding the limitation of methods based on second-order statistics, By deriving a number of sufficient conditions, we characterize several classes of band-limited channels that are not identifiable from only the second-order statistics of the channel output.