Shuichi Ohno Georgios B. Giannakis Optimal training and redundant precoding for block transmissions with application to wireless OFDM. 2113-2123 2002 50 IEEE Transactions on Communications 12 http://dx.doi.org/10.1109/TCOMM.2002.806547 db/journals/tcom/tcom50.html#OhnoG02