Downlink transmit beamforming
First Claim
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1. 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.
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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.
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Citations
19 Claims
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1. A method comprising:
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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. - View Dependent Claims (2, 3, 4, 5)
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6. A method comprising:
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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. - View Dependent Claims (7, 8, 9, 10)
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11. A wireless network access point comprising:
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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. - View Dependent Claims (12, 13, 14, 15)
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16. 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. - View Dependent Claims (17, 18, 19)
Specification