▁ 5 0 ▁U . S . ▁pat ents . ▁He ▁author ed ▁a ▁labor atory ▁manual ▁that ▁teach es ▁the ▁principles ▁of ▁wireless ▁communication ▁to ▁under grad uate ▁students ▁ ▁and ▁co - author ed ▁a ▁book ▁on ▁millimeter ▁wave ▁wireless ▁communication . ▁He ▁is ▁particularly ▁known ▁for ▁his ▁work ▁on ▁different ▁aspects ▁of ▁M I MO ▁communication ▁systems . ▁ ▁Professional ▁career ▁He ath ' s ▁early ▁work ▁at ▁Stan ford ▁advanced ▁the ▁then ▁nas cent ▁field ▁of ▁M I MO ▁communication . ▁During ▁his ▁Ph . D . ▁he ▁took ▁a ▁leave ▁of ▁absence ▁to ▁be ▁one ▁of ▁the ▁first ▁employees ▁at ▁I osp an ▁W ire less ▁( ear lier ▁known ▁as ▁G ig ab it ▁W ire less ▁Inc ), ▁where ▁he ▁was ▁part ▁of ▁a ▁small ▁team ▁that ▁created ▁the ▁first ▁practical ▁M I MO - OF DM ▁radio ▁( a ▁prede cess or ▁of ▁what ▁we ▁now ▁know ▁as ▁IE EE ▁ 8 0 2 . 1 1 n ). ▁ ▁His ▁work ▁at ▁I osp an ▁resulted ▁in ▁several ▁early ▁pat ents ▁on ▁critical ▁M I MO ▁techn ologies . ▁ ▁He ath ' s ▁work ▁at ▁I osp an ▁led ▁to ▁his ▁discovery ▁that , ▁depending ▁on ▁the ▁wireless ▁propag ation ▁conditions , ▁different ▁M I MO ▁configurations , ▁e . g ., ▁spatial ▁multiple x ing ▁or ▁space - time ▁coding , ▁are ▁preferred . ▁He ath ' s ▁discovery ▁opened ▁new ▁research ▁a ven ues ▁to ▁enh ance ▁the ▁fundamental ▁understanding ▁of