Determining a response of a rapidly varying OFDM communication channel using an observation scalar
First Claim
1. A channel estimator, comprising:
- a first stage configurable to generate a first observation scalar for a first communication path of a communication channel;
a second stage configurable to generate channel estimation coefficients in response to the first observation scalar;
a first Kalman filter configurable to generate in response to the first observation scalar first intermediate coefficients;
a third stage configurable to generate first path estimation coefficients in response to the first intermediate coefficients;
a fourth stage configurable to generate a second observation scalar for a second communication path of the communication channel;
a second Kalman filter configurable to generate in response to the second observation scalar second intermediate coefficients;
a fifth stage configurable to generate second path estimation coefficients in response to the second intermediate coefficients; and
wherein the second stage is configurable to generate the channel estimation coefficients in response to the first and second path estimation coefficients.
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Abstract
In an embodiment, a channel estimator includes first and second stages. The first stage is configurable to generate an observation scalar for a communication path of a communication channel, and the second stage is configurable to generate channel-estimation coefficients in response to the first observation scalar. For example, such a channel estimator may use a recursive algorithm, such as a VSSO Kalman algorithm, to estimate the response of a channel over which propagates an OFDM signal that suffers from ICI due to Doppler spread. Such a channel estimator may estimate the channel response more accurately, more efficiently, with a less-complex algorithm, and with less-complex software or circuitry, than conventional channel estimators. Furthermore, such a channel estimator may be able to dynamically account for changes in the number of communication paths that compose the channel, changes in the delays of these paths, and changes in the signal-energy levels of these paths.
47 Citations
20 Claims
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1. A channel estimator, comprising:
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a first stage configurable to generate a first observation scalar for a first communication path of a communication channel; a second stage configurable to generate channel estimation coefficients in response to the first observation scalar; a first Kalman filter configurable to generate in response to the first observation scalar first intermediate coefficients; a third stage configurable to generate first path estimation coefficients in response to the first intermediate coefficients; a fourth stage configurable to generate a second observation scalar for a second communication path of the communication channel; a second Kalman filter configurable to generate in response to the second observation scalar second intermediate coefficients; a fifth stage configurable to generate second path estimation coefficients in response to the second intermediate coefficients; and wherein the second stage is configurable to generate the channel estimation coefficients in response to the first and second path estimation coefficients. - View Dependent Claims (2, 3, 4)
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5. A receiver, comprising:
a channel estimator, including; a first stage configurable to generate a first observation scalar for a first communication path of a communication channel; a second stage configurable to generate channel estimation coefficients in response to the first observation scalar; a first Kalman filter configurable to generate in response to the first observation scalar first intermediate coefficients; a third stage configurable to generate first path estimation coefficients in response to the first intermediate coefficients; a fourth stage configurable to generate a second observation scalar for a second communication path of the communication channel; a second Kalman filter configurable to generate in response to the second observation scalar second intermediate coefficients; and a fifth stage configurable to generate second path estimation coefficients in response to the second intermediate coefficients; wherein the second stage is configurable to generate the channel estimation coefficients in response to the first and second path estimation coefficients. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A transmitter-receiver, comprising:
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a receiver configurable to receive a first orthogonal frequency division multiplexed signal from a communication channel having a communication path, the receiver including; a channel estimator, including; a first stage configurable to generate from the first signal a first observation scalar for the communication path; and a second stage configurable to generate channel estimation coefficients in response to the first observation scalar; a first Kalman filter configurable to generate in response to the first observation scalar first intermediate coefficients; a third stage configurable to generate first path estimation coefficients in response to the first intermediate coefficients; a fourth stage configurable to generate a second observation scalar for a second communication path of the communication channel; a second Kalman filter configurable to generate in response to the second observation scalar second intermediate coefficients; and a fifth stage configurable to generate second path estimation coefficients in response to the second intermediate coefficients; wherein the second stage is configurable to generate the channel estimation coefficients in response to the first and second path estimation coefficients; and a transmitter configurable to transmit a second orthogonal frequency division multiplexed signal. - View Dependent Claims (13)
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14. A system, comprising:
a first transmitter-receiver, including; a first receiver configurable to receive a first orthogonal frequency division multiplexed signal from a communication channel having a communication path, the receiver including; a channel estimator, including; a first stage configurable to generate from the first signal a first observation scalar for the communication path; a second stage configurable to generate channel estimation coefficients in response to the first observation scalar; a first Kalman filter configurable to generate in response to the first observation scalar first intermediate coefficients; a third stage configurable to generate first path estimation coefficients in response to the first intermediate coefficients; a fourth stage configurable to generate a second observation scalar for a second communication path of the communication channel; a second Kalman filter configurable to generate in response to the second observation scalar second intermediate coefficients; and a fifth stage configurable to generate second path estimation coefficients in response to the second intermediate coefficients; wherein the second stage is configurable to generate the channel estimation coefficients in response to the first and second path estimation coefficients; a first transmitter configurable to transmit a second orthogonal frequency division multiplexed signal; and a second transmitter-receiver including; a second receiver configurable to receive the second signal from the first transmitter, and a second transmitter configurable to transmit the first signal to the first receiver.
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15. A non-transitory computer-readable medium storing instructions that when executed by a computing apparatus cause the apparatus to perform steps comprising:
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generating an observation scalar for a communication path of a communication channel; generating channel estimation coefficients in response to the observation scalar; generating, in response to the first observation scalar, first intermediate coefficients using a first Kalman filtering operation; generating first path estimation coefficients in response to the first intermediate coefficients; generating a second observation scalar for a second communication path of the communication channel; generating, in response to the second observation scalar, second intermediate coefficients using a second Kalman filtering operation; and generating second path estimation coefficients in response to the second intermediate coefficients; wherein the channel estimation coefficients are generated in response to the first and second path estimation coefficients.
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16. A method, comprising:
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receiving a signal over a communication channel having a number of communication paths; generating in response to the signal a first observation scalar for a first one of the communication paths; and estimating channel coefficients in response to the first observation scalar; generating, in response to the first observation scalar, first intermediate coefficients using a first Kalman filtering operation; generating first path estimation coefficients in response to the first intermediate coefficients; generating a second observation scalar for a second communication path of the communication channel; generating, in response to the second observation scalar, second intermediate coefficients using a second Kalman filtering operation; and generating second path estimation coefficients in response to the second intermediate coefficients; wherein the channel estimation coefficients are generated in response to the first and second path estimation coefficients. - View Dependent Claims (17, 18, 19, 20)
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Specification