Channel estimation in OFDMA for switched antenna array based angle-of-arrival location
First Claim
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1. A method comprising:
- detecting at a plurality of antennas of at least one wireless device, energy spanning a frequency bandwidth that may include a transmission from each of one or more source devices, wherein a transmission from a source device occupies a unique set of subcarriers in a sub-band of the frequency bandwidth;
generating at least one reference receive signal from at least one designated antenna;
switching among the plurality of antennas, excluding the at least one designated antenna, over time, to generate a plurality of antenna-specific receive signals for a corresponding antenna state, each for a different time interval;
computing a first channel estimate based on the at least one reference receive signal;
decoding at least a portion of a frame for one of the transmissions based on the first channel estimate to recover symbol data;
computing a second channel estimate based on the plurality of antenna-specific receive signals;
generating a composite channel estimate from at least one of the first channel estimate and the second channel estimate;
using the composite channel estimate, computing an angle of arrival vector for a transmission from a corresponding source device of the one or more source devices; and
deriving a location estimate for the corresponding source device of the one or more source devices based at least in part on the angle of arrival vector for the corresponding source device.
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Abstract
Techniques are presented herein for computing angle-of-arrival estimates while switching antenna states during a packet unit for the general Orthogonal Frequency Division Multiple Access (OFMDA) case (including a single user). A wireless device computes channel estimates throughout the entire frame and not only during the training symbols. Consequently, the wireless device computes channel estimates for all antennas in its array within a single frame instead of having to wait for multiple frames.
120 Citations
20 Claims
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1. A method comprising:
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detecting at a plurality of antennas of at least one wireless device, energy spanning a frequency bandwidth that may include a transmission from each of one or more source devices, wherein a transmission from a source device occupies a unique set of subcarriers in a sub-band of the frequency bandwidth; generating at least one reference receive signal from at least one designated antenna; switching among the plurality of antennas, excluding the at least one designated antenna, over time, to generate a plurality of antenna-specific receive signals for a corresponding antenna state, each for a different time interval; computing a first channel estimate based on the at least one reference receive signal; decoding at least a portion of a frame for one of the transmissions based on the first channel estimate to recover symbol data; computing a second channel estimate based on the plurality of antenna-specific receive signals; generating a composite channel estimate from at least one of the first channel estimate and the second channel estimate; using the composite channel estimate, computing an angle of arrival vector for a transmission from a corresponding source device of the one or more source devices; and deriving a location estimate for the corresponding source device of the one or more source devices based at least in part on the angle of arrival vector for the corresponding source device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
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8. A method comprising:
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detecting at a plurality of antennas of at least one wireless device, energy spanning a frequency bandwidth that may include a transmission from each of one or more source devices, wherein a transmission from a source device occupies a unique set of subcarriers in a sub-band of the frequency bandwidth; generating at least one reference receive signal from at least one designated antenna; switching among the plurality of antennas, excluding the at least one designated antenna, over time, to generate a plurality of antenna-specific receive signals for a corresponding antenna state, each for a different time interval; computing a first channel estimate based on the at least one reference receive signal; decoding at least a portion of a frame for one of the transmissions based on the first channel estimate to recover symbol data; filtering samples of the plurality of antenna-specific receive signals with a filter bank that separates antenna-specific receive signals for a corresponding source device of the one or more source devices, to produce a filtered output; performing a cross correlation on the filtered output to generate a plurality of cross correlation outputs, one for each of the plurality of antennas, excluding the at least one designated antenna, to produce cross correlation outputs that comprise separate cross correlation samples for each antenna state; storing the cross correlation samples mapped by antenna state and filter bank index associated with a corresponding source device; converting the cross correlation outputs to an angle of arrival vector for each source device of the one or more source devices; and deriving a location estimate for the corresponding source device of the one or more source devices based, at least in part, on the angle of arrival vector for the corresponding source device. - View Dependent Claims (9, 12)
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13. An apparatus comprising:
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a plurality of antennas configured to detect wireless transmissions spanning a frequency bandwidth that may include a transmission from each of one or more source devices, wherein a transmission from a source device occupies a unique set of subcarriers in a sub-band of the frequency bandwidth; a first radio receiver coupled to a first antenna of the plurality of antennas, the first radio receiver configured to generate at least one reference receive signal; a second radio receiver; a switch coupled to the plurality of antennas excluding the first antenna, and to the second radio receiver, the switch configured to switch over time among the plurality of antennas excluding the first antenna to connect one of the plurality of antennas, excluding the first antenna, to the second radio receiver to generate a plurality of antenna-specific receive signals for a corresponding antenna state, each for a different time interval; a processor coupled to the first radio receiver and the second radio receiver, wherein the processor is configured to; compute a first channel estimate based on the at least one reference receive signal; decode at least a portion of a frame for one of the transmissions based on the first channel estimate to recover symbol data; compute a second channel estimate based on the plurality of antenna-specific receive signals; generate a composite channel estimate from at least one of the first channel estimate and the second channel estimate; using the composite channel estimate, compute an angle of arrival vector for a transmission from a corresponding source device of the one or more source devices; and derive a location estimate for the corresponding source device of the one or more source devices based at least in part on the angle of arrival vector for the corresponding source device. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification