# US 2014/0192915 A1 · Multi-user mimo-sdma for finite rate feedback systems

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- Number: US 2014/0192915 A1
- Document ID: US20140192915A1
- Status: Published application
- Kind: A1
- Application number: 13/888,094
- Filed: 2013-05-06
- Published: 2014-07-10
- Earliest claimed: 2007-01-05
- Assignees: Apple Inc.
- Inventors: Jayakrishnan C. Mundarath; Jayesh H. Kotecha
- Web page: https://patentgrep.com/patent/US20140192915A1

## CPC

- H04B 7/0417: Feedback systems
- H04B 7/0632: {Channel quality parameters, e.g. channel quality indicator [CQI]}
- H04B 7/0634: {Antenna weights or vector/matrix coefficients}
- H04B 7/0857: {using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]}
- H04B 7/086: {using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming}
- H04L 5/14: Two-way operation using the same type of signal, i.e. duplex
- H04W 88/02: Terminal devices
- H04W 88/08: Access point devices
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable precoding 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 (pi) which estimates file 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.

## Claims

### Claim at position 1

1-23. (canceled)

### Claim 24

A method of operating a mobile wireless communications device operable in a multiple input, multiple output (MIMO) space division multiple access (SDMA) communications mode, the method comprising:
receiving one or more signals from a base station at the mobile wireless communications device;
determining a parameter related to a transmission channel based at least in part on the one or more signals;
determining (i) a receive beamforming vector for the transmission channel and (ii) a codeword using a predetermined channel quality indicator (CQI) metric; and
transmitting feedback information to a base station, the feedback information being representative of at least the codeword.

### Claim 25

A mobile wireless communications device operable in a multiple input, multiple output (MIMO) space division multiple access (SDMA) communications mode, the device comprising:
processing apparatus; and
logic in data communication with the processing apparatus, the logic configured to:
receive one or more signals from a base station;
determine a parameter related to a transmission channel based at least in part on the one or more signals;
determine a receive beamforming vector for the transmission channel;
determine a codeword using a predetermined channel quality indicator (CQI) metric; and
transmit feedback information to the base station, the feedback information being representative of at least the codeword.

### Claim 26

A mobile wireless communications system, comprising:
a base station; and
a mobile device operable in a multiple input, multiple output (MIMO) space division multiple access (SDMA) communications mode, the device comprising:
processing apparatus; and
logic in data communication with the processing apparatus, the logic configured to:
receive one or more signals from the base station;
determine a parameter related to a transmission channel based at least in part on the one or more signals;
determine a receive beamforming vector for the transmission channel;
determine a codeword using a predetermined channel quality indicator (CQI) metric; and
transmit feedback information to the base station, the feedback information being representative of at least the codeword.