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US 7,719,993 B2Granted
Downlink transmit beamforming
AssigneeIntel Corporation
InventorsQinghua Li, Xintian E. Lin
Life of this patent
Estimating the term…
Abstract
A wireless network access point can operate as a closed loop MIMO device when communicating with a station that is operating as an open loop MIMO device. Transmit/receive chains in the access point are calibrated to support aggregate channel reciprocity.
Claims19
A method comprising:
- calibrating a plurality of transmit/receive chains in a wireless network access point device, wherein calibrating comprises determining a ratio of transmitter gain to receiver gain for each of the plurality of transmit/receive chains in terms of a ratio of transmitter gain to receiver gain for one of the plurality of transmit/receive chains, and adjusting gain values to make the transmitter gain to receiver gain ratios substantially equal;
- receiving an open loop packet from a station having a first antenna and a second antenna;
- determining a downlink beamforming matrix as a pseudo-inverse of an transpose of the aggregate uplink channel matrix;
- and
- transmitting a first data stream to the first antenna of the station, and transmitting a second data stream to the second antenna of the station.
2 more elements
A method comprising:
- determining a ratio of transmitter gain to receiver gain for each of a plurality of transmitter/receiver pairs in an access point in terms of a ratio of transmitter gain to receiver gain for one of the plurality of transmitter/receiver pairs;
- adjusting gain values of transmitter/receiver pairs in the access point to cause the ratios to be substantially equal;
- and
- forming at least two antenna beams to transmit separate data streams to separate antennas at a single station.
1 more element
A wireless network access point comprising:
- a plurality of transmit/receive chain pairs;
- and
- a processing element, which is operable to calibrate the transmit/receive chain pairs by determining a ratio of transmitter gain to receiver gain for each of a plurality of transmit/receive chain pairs in the wireless network access point in terms of a ratio of transmitter gain to receiver gain for one of the plurality of transmit/receive chain pairs and adjusting gain values so that ratios of transmit gain to receive gain for each transmit/receive chain pair are substantially equal, and to provide a beamforming matrix to form at least two beams to communicate separately with at least two antennas on one station.
An article comprising:
- a machine-readable medium adapted to hold instructions that when accessed result in a wireless network access point determining a ratio of transmitter gain to receiver gain for each of a plurality of transmitter/receiver pairs in a wireless network access point in terms of a ratio of transmitter gain to receiver gain for one of the plurality of transmitter/receiver pairs, adjusting gain values of transmitter/receiver pairs to cause the ratios to be substantially equal, and forming at least two antenna beams to transmit separate data streams to separate antennas at a single station.
Dependencies are inferred from the claim text.