US 5,634,199 AGranted

Method of subspace beamforming using adaptive transmitting antennas with feedback

AssigneeStanford University

InventorsDerek Gerlach, Arogyaswami Paulraj, Gregory G. Raleigh

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Abstract

A method is disclosed for using feedback to reduce crosstalk between mobile receivers in a wireless communications system comprising an adaptive transmitting antenna array. Feedback signals from the receivers are time-averaged and used to calculate a set of weight vectors that minimize crosstalk and maximize desired signal without requiring burdensome feedback rates. Beamforming diversity is combined with feedback through the use of diversity vectors. The preferred embodiment includes a method for obtaining the required feedback by exploiting the SAT circuitry present in the AMPS system currently in use. Consequently, the method may be implemented without modification to existing cellular phone handsets.

Claims10

Dependent claims

A method for minimizing crosstalk in a wireless communications system comprising an array of transmitting elements and a set of receivers, the method comprising the steps of:

transmitting from the array to the receivers a set of transmitted signals chosen from the group consisting of a set of information signals and a set of probing signals, where the transmitting is in accordance with a set of initial weight vectors;
feeding back to the array a set of feedback signals, where each of the feedback signals is derived from the response at one of the receivers to the set of transmitted signals;
calculating from the set of feedback signals a set of new information weight vectors that minimize time-average crosstalk between the receivers and maximize time-average desired signal at each receiver;
and
transmitting the set of information signals from the array to the receivers in accordance with the set of new information weight vectors.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/424,662Filed 17 Apr 1995 · continuation in part
Priority: 14 Apr 1993
Granted: 27 May 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H01Q 3/2605
Varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of…
H04B 1/126
Using adaptive balancing or compensation means: having multiple inputs, e.g. auxiliary antenna for receiving interfering signal
H04B 7/0626
Feedback content: channel coefficients, e.g. channel state information [CSI]
H04B 7/0617
Of weighted versions of same signal: for beam forming