Design and performance analysis of collaborative spatial multiplexing for IEEE 802.16e-based systems. - Krishna Balachandran; Doru Calin; Nandu Gopalakrishnan; Joseph H. Kang; Achilles G. Kogiantis; Shupeng Li; Lawrence H. Ozarow; Sudhir Ramakrishna; Ashok N. Rudrapatna; Russell Sun (Bell Labs Tech. J., 2009)