In this paper, the problem of preamble-based channel estimation in OFDM offset QAM (OFDM/OQAM) systems under a deterministic channel assumption is studied. Recent results indicate that full (all tones carrying pilot symbols) preambles with equal pilot symbols are locally optimal, in the sense that they yield a local minimum of the mean square error (MSE) performance metric of the estimated channel frequency response (CFR), subject to a total training energy constraint. We study the problem of finding the globally optimal full preamble. We show that under a channel constancy assumption, the global optimum coincides with the full preamble of equal symbols. The same result holds even if the channel constancy assumption is removed. Numerical simulations are presented to support the derived results.
['Dimitrios Katselis', 'Mats Bengtsson', 'Cristian R. Rojas', 'Hakan Hjalmarssona', 'Eleftherios Kofidisb']
On preamble-based channel estimation in OFDM/OQAM systems