Fractionally spaced blind equalization of FIR channels under symbol timing offsets

Considers the problem of blind estimation and equalization of digital communication FIR channels using fractionally spaced samples. Fractionally sampled data are cyclostationary rather than stationary. The problem is cast into a mathematical framework of parameter estimation for a vector stationary process with single input (information sequence) and multiple outputs, by using a time-series representation of a cyclostationary process. The channel parameters are estimated by first estimating various subchannels using the second and the fourth order cumulant function of the received data, and then appropriately aligning and scaling them. The estimated channel impulse response is then used to construct a linear equalizer. An illustrative simulation example using a 16-QAM signal is presented where the effect of symbol-timing-phase offset is studied via simulations