Coherence time estimation and mobility detection for wireless channel
First Claim
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1. A method comprising:
- at a first wireless communication device, receiving, over a period of time, at a plurality of antennas transmissions in a channel from a second wireless communication device to produce a corresponding plurality of antenna-specific receive signals;
computing from the plurality of antenna-specific receive signals a plurality of channel estimates for a channel between the first wireless communication device and the second wireless communication device;
computing a channel observation parameter from each of the plurality of channel estimates, wherein the channel observation parameters represent conditions of the channel between the first wireless communication device and the second wireless communication device at a time instance;
storing the channel observation parameters computed for each of the plurality of channel estimates at the first wireless communication device;
determining combinations of the channel observation parameters;
for each determined combination of channel observation parameters, computing data representing differences between the channel observation parameters in the respective combination;
storing the data representing the differences in bins that each correspond to a range of time intervals, wherein the data representing the differences are each stored in a bin corresponding to a range of time intervals that encompasses the time interval between time of reception of the transmissions corresponding to the channel observations parameters used to compute the respective differences; and
generating an estimate of the coherence time of the channel based on a distribution of the data representing the differences stored in the bins.
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Abstract
Techniques are provided to measure how fast a wireless channel is changing between a first wireless communication device (e.g., a wireless base station or access point) and a second wireless device (e.g., a wireless client device) based on signals that the first communication wireless device receives at a plurality of antennas from a second wireless communication device. Techniques are also provided to measure a degree of mobility of the second wireless communication device based on signals received at the first communication wireless device from the second communication wireless device.
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Citations
25 Claims
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1. A method comprising:
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at a first wireless communication device, receiving, over a period of time, at a plurality of antennas transmissions in a channel from a second wireless communication device to produce a corresponding plurality of antenna-specific receive signals; computing from the plurality of antenna-specific receive signals a plurality of channel estimates for a channel between the first wireless communication device and the second wireless communication device; computing a channel observation parameter from each of the plurality of channel estimates, wherein the channel observation parameters represent conditions of the channel between the first wireless communication device and the second wireless communication device at a time instance; storing the channel observation parameters computed for each of the plurality of channel estimates at the first wireless communication device; determining combinations of the channel observation parameters; for each determined combination of channel observation parameters, computing data representing differences between the channel observation parameters in the respective combination; storing the data representing the differences in bins that each correspond to a range of time intervals, wherein the data representing the differences are each stored in a bin corresponding to a range of time intervals that encompasses the time interval between time of reception of the transmissions corresponding to the channel observations parameters used to compute the respective differences; and generating an estimate of the coherence time of the channel based on a distribution of the data representing the differences stored in the bins. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus comprising.
a plurality of antennas; -
a radio receiver configured to be coupled to the plurality of antennas and to generate a plurality of antenna-specific receive signals derived from a transmission sent by an other wireless communication device over a period of time and detected at the plurality of antennas; a controller coupled to the radio receiver and configured to; generate from the plurality of antenna-specific receive signals a plurality of channel estimates for a channel with respect to the other wireless communication device; compute a channel observation parameter from each of the channel estimates, wherein the channel observation parameters represent conditions of the channel with respect to the other wireless communication device at a time instance; store the channel observation parameters computed for each of the plurality of channel estimates; determine combinations of the channel observation parameters; for each determined combination of channel observation parameters, compute data representing differences between the channel observation parameters in the respective combination; store the data representing the differences in bins that each correspond to a range of time intervals, wherein the data representing the differences are each stored in a bin corresponding to a range of time intervals that encompasses the time interval between time of reception of the transmissions corresponding to the channel observations parameters used to compute the respective differences; and generate an estimate of the coherence time of the channel based on a distribution of the data representing the differences stored in the bins. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A non-transitory computer-readable medium encoded with instructions that, when executed by a processor, cause the processor to:
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generate from a plurality of antenna-specific receive signals derived from a transmission received over a period of time at a plurality of antennas of a first wireless communication from a second wireless communication device, a plurality of channel estimates for a channel between the first wireless communication device and the second wireless communication device; compute a plurality of channel observation parameters from the channel estimates, wherein the channel observation parameters represent conditions of the channel between the first wireless communication device and the second wireless communication device at a time instance; store the channel observation parameters computed for each of the plurality of channel estimates at the first wireless communication device; determine combinations of the channel observation parameters; for each determined combination of channel observation parameters, compute data representing differences between the channel observation parameters in the respective combination; store the data representing the differences in bins that each correspond to a range of time intervals, wherein the data representing the differences are each stored in a bin corresponding to a range of time intervals that encompasses the time interval between time of reception of the transmissions corresponding to the channel observations parameters used to compute the respective differences; and generate an estimate of the coherence time of the channel based on a distribution of the data representing the differences stored in the bins. - View Dependent Claims (17, 18, 19)
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20. A method comprising:
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at a first wireless communication device, receiving, over a period of time, at a plurality of antennas transmissions in a channel from a second wireless communication device to produce a corresponding plurality of antenna-specific receive signals; computing from the plurality of antenna-specific receive signals a plurality of channel estimates for a channel between the first wireless communication device and the second wireless communication device; computing a channel observation parameter from each of the channel estimates, wherein the channel observation parameters represent conditions of the channel at a plurality of subcarriers; comparing corresponding subcarriers of the channel observation parameters computed for successive transmissions; and generating an indication as to whether the second wireless communication device is moving or stationary with respect to the first wireless communication device based on the number of subcarriers determined to exhibit a difference. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification