Recent theoretical results describing the sum-capacity when using multiple antennas to communicate with multiple users in a rich scattering environment have not yet been followed with practical transmission schemes that achieve this capacity. We introduce a simple encoding algorithm that achieves near-capacity at sum-rates of tens of bits/channel-use. The algorithm is a variation on channel inversion that regularizes the inverse and uses a ``sphere encoder'' to perturb the data to reduce the energy of the transmitted signal. The performance difference between channel inversion with and without this perturbation is shown to be dramatic. With the perturbation, we can achieve linear growth in the sum-rate with the number of users. The results of both uncoded and turbo-coded simulations are presented. This is joint work with C. Peel and A. L. Swindlehurst, BYU.

Bertrand Hochwald was born in New York, NY. He received his undergraduate education from Swarthmore College, Swarthmore, PA and the M.S. in electrical engineering from Duke University, Durham, NC. From 1986 to 1989 he worked for the Department of Defense at Fort Meade, MD. In 1989 he enrolled at Yale University, New Haven, CT, where he received the M.A. in statistics and the Ph.D. in electrical engineering. In 1995-1996 he was a research associate and visiting assistant professor at the Coordinated Science Laboratory, University of Illinois, Urbana-Champaign. He joined the Mathematics of Communications Research Department at Lucent Technologies Bell Laboratories in September, 1996. He is now a Distinguished Member of the Technical Staff.

He is the recipient of several achievement awards while employed at the Department of Defense and the Prize Teaching Fellowship at Yale. His interests include communications and information theory, probability theory, and statistical signal processing.