A closed-form performance upper-bound on the finite-length MMSE-DFE with arbitrary decision delay

A simple analytical upper-bound on the decision-point SNR of the unbiased finite-length MMSE-DFE with arbitrary decision delay is derived. The bound can be easily computed given the channel impulse response, input SNR, length of feedforward filter, and desired decision delay. The bound is shown to be tighter than the matched-filter bound. A by-product is a computationally-efficient method for setting the decision delay.