Iterative optimization of FIR precoder for frequency-selective MIMO channel

The frequency selectivity of wireless channels makes the multiple-input multiple-output (MIMO) precoder design significantly more complicated than its counterpart in the frequency-flat fading channels. In this paper, a new precoder with finite impulse response (FIR) structure is proposed for maximizing the throughput of frequency-selective MIMO channels under an average transmit power constraint. We investigate an iteration mechanism by tracking two associated parameters, named as the innovation orientation and the iteration step size, so as to obtain the desired FIR precoding matrix. The convex optimization program and the traditional Gauss-Newton approach are exploited to derive the update equations and the relationship among different parameters. The analytical and numerical results are presented to indicate the efficiency of the proposed method in the high signal to noise ratio (SNR) regime.