US 2008/0165875 A1Published application

Multi-user MIMO-SDMA for finite rate feedback systems

AssigneeApple Inc.

InventorsJayakrishnan C. Mundarath, Jayesh H. Kotecha

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Abstract

A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable preceding for multi-stream transmission, where a channel codeword (ui) and one or more channel quality indicator values (CQIA, CQIB) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (ρi) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (ui) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.

Claims23

Dependent claims

A channel information feedback method for a multiple input, multiple output (MIMO) space division multiple access (SDMA) system, comprising:

estimating channel state information for a transmission channel from a transmitting device to a first receiving device by receiving one or more signals;
generating a receive beamforming vector v for the transmission channel and a codeword u which represents a product of the receive beamforming vector v and a channel matrix H for the transmission channel;
generating a first estimated channel quality indicator for the transmission channel based on the codeword u and receive beamforming vector v, where the first estimated channel quality indicator is computed for a minimum interference case where there is a minimum number of receiving devices sharing a time-frequency resource block with the first receiving device;
generating a second estimated channel quality indicator for the transmission channel based on the codeword u and receive beamforming vector v, where the second estimated channel quality indicator is computed for an additional interference case where there is more than the minimum number of receiving devices sharing a time-frequency resource block with the first receiving device;
and
transmitting feedback information to the transmitting device that is representative of the codeword u and at least one of the first or second estimated channel quality indicators.

3 more elements

Dependencies are inferred from the claim text.