A Vector-Perturbation Technique for Near-Capacity Multi-Antenna Multi-User Commu

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Abstract: Recent theoretical results describing the sum-capacity when using multiple antennas to communicate with multiple users in a known 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.

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