▁performance ▁limitations ▁in ▁M I MO ▁wireless ▁communication . ▁ ▁From ▁his ▁divers ity ▁and ▁multiple x ing ▁discovery , ▁he ▁also ▁recognized ▁the ▁critical ▁importance ▁of ▁feedback ▁and ▁adaptation ▁in ▁M I MO ▁wireless ▁systems , ▁i . e ., ▁to ▁make ▁M I MO ▁wireless ▁communication ▁commer cially ▁vi able ▁the ▁receiver ▁must ▁inform ▁the ▁transmit ter ▁about ▁the ▁best ▁M I MO ▁configuration ▁before ▁communication ▁▁ ▁At ▁U T ▁Austin , ▁based ▁on ▁his ▁ins ights ▁into ▁the ▁importance ▁of ▁feedback ▁in ▁M I MO ▁communication , ▁he ▁pione ered ▁M I MO ▁feedback ▁strateg ies ▁( limited ▁feedback ▁prec oding ). ▁ ▁He ath ▁was ▁able ▁to ▁construct ▁a ▁strategy ▁for ▁which ▁the ▁overhead ▁penalty ▁for ▁feedback ▁was ▁very ▁small ▁( only ▁a ▁few ▁bits ▁of ▁feedback ▁required ▁to ▁configure ▁an ▁entire ▁M I MO ▁transmit ter ). ▁ ▁This ▁allowed ▁practical ▁M I MO ▁wireless ▁communication ▁to ▁achieve ▁data ▁rates ▁and ▁link ▁reli ability ▁very ▁close ▁to ▁theoretical ▁expect ations ▁by ▁varying ▁the ▁number ▁of ▁spatial ▁multiple x ing ▁streams . ▁ ▁View s ▁on ▁ 5 G ▁He ath ▁is ▁an ▁advoc ate ▁of ▁moving ▁to ▁millimeter - wave ▁spectrum ▁for ▁the ▁ 5 G ▁cell ular ▁standard ization . ▁He ▁recogn izes , ▁however , ▁that ▁ 5 G ▁cell ular ▁deploy ments ▁will ▁likely ▁require ▁significant ▁changes ▁to ▁cell ular ▁planning . ▁ ▁He ▁has ▁predicted ▁that , ▁due ▁to ▁block age , ▁millimeter ▁wave ▁cell ular ▁will ▁need ▁to ▁be ▁much ▁more ▁dens ely