Channel estimation feedback in an orthogonal frequency division multiplexing system or the like
First Claim
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1. A method for channel estimation in an OFDM system, the method comprising:
- quantizing a channel response function of a signal received from a transmitter or a residual value of the channel response function, wherein the channel response function is represented by M complex numbers, wherein a channel estimate is subtracted from the channel response function to provide the residual value;
limiting the channel response function to N complex numbers where N is less than M, wherein the N complex numbers are limited to values having time delays less than a predetermined delay spread;
converting the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to said quantizing; and
generating a channel state information packet to be transmitted back to the transmitter, wherein the packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption, and includes the quantized residual value of the channel response function otherwise, andwherein the channel state information permits the transmitter to obtain a channel state estimation.
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Abstract
Briefly, in accordance with one embodiment of the invention, a channel state information packet is encoded by a receiver side device and is fed back to the transmitter side device. The transmitter side device decodes the channel state information packet to extract an estimate of the channel response function.
16 Citations
22 Claims
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1. A method for channel estimation in an OFDM system, the method comprising:
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quantizing a channel response function of a signal received from a transmitter or a residual value of the channel response function, wherein the channel response function is represented by M complex numbers, wherein a channel estimate is subtracted from the channel response function to provide the residual value; limiting the channel response function to N complex numbers where N is less than M, wherein the N complex numbers are limited to values having time delays less than a predetermined delay spread; converting the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to said quantizing; and generating a channel state information packet to be transmitted back to the transmitter, wherein the packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption, and includes the quantized residual value of the channel response function otherwise, and wherein the channel state information permits the transmitter to obtain a channel state estimation. - View Dependent Claims (2, 3, 4)
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5. An article comprising:
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a storage medium having stored thereon instructions that, when executed by a computing platform, result in the encoding of a channel state information packet by; quantizing a channel response function of a signal received from a transmitter or a residual value of the channel response function, wherein the channel response function is represented by M complex numbers, and wherein a channel estimate is subtracted from the channel response function to provide the residual value; limiting the channel response function to N complex numbers where N is less than M, wherein the N complex numbers are limited to values having time delays less than a predetermined delay spread; converting the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to said quantizing; and generating a channel state information packet to be transmitted back to the transmitter, wherein the packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption, and includes the quantized residual value of the channel response function otherwise, and wherein the channel state information permits the transmitter to obtain a channel state estimation. - View Dependent Claims (6, 7, 8, 9)
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10. A method for channel estimation in an OFDM system, the method comprising:
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parsing a channel state information packet received from a device after transmitting a signal to the device to obtain a quantized channel response function of the signal, wherein the device converts the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to quantization, wherein the channel state information packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption and includes a quantized residual value of the channel response function otherwise, wherein a channel estimate is subtracted from the channel response function to provide the residual value; and dequantizing the quantized channel response function to provide a channel response function, wherein the channel response function is an estimate of the channel response function, wherein the estimate of the channel response function is represented by N complex numbers, wherein the channel response function is represented by M complex numbers, and wherein N is less than M. - View Dependent Claims (11, 12)
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13. An article, comprising:
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a storage medium having stored thereon instructions that, when executed by a computing platform, result in the decoding of a channel state information packet by; parsing a channel state information packet received from a device after transmitting a signal to the device to obtain a quantized channel response function of the signal wherein the channel state information packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption and includes a quantized residual value of the channel response function otherwise, wherein a channel estimate is subtracted from the channel response function to provide the residual value, and wherein the device converts the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to quantization; and dequantizing the quantized channel response function to provide a channel response function, wherein the channel response function is an estimate of the channel response function, wherein the estimate of the channel response function is represented by N complex numbers, wherein the channel response function is represented by M complex numbers, and wherein N is less than M. - View Dependent Claims (14, 15)
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16. An apparatus, comprising:
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a baseband processor; and a transceiver to couple to said baseband processor and an omnidirectional antenna; wherein said baseband processor; quantizes a channel response function of a signal received from a transmitter via said transceiver or a residual value of the channel response function, wherein the channel response function is represented by M complex numbers, and wherein a channel estimate is subtracted from the channel response function to provide the residual value; limits the channel response function to N complex numbers, wherein N is less than M wherein the N complex numbers are limited to values having time delays less than a predetermined delay spread; converts the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to quantizing the channel response function; and generates a channel state information packet to be transmitted back to the transmitter wherein the packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption, and includes the quantized residual value of the channel response function otherwise. - View Dependent Claims (17, 18, 19)
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20. An apparatus, comprising:
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a baseband processor; and a transceiver to couple to said baseband processor and an omnidirectional antenna; wherein said baseband processor parses a channel state information packet received from a device after transmitting a signal to the device to obtain a quantized channel response function of the signal to obtain a quantized channel response function of the signal, wherein the device converts the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to quantizing the channel response function, wherein the channel state information packet includes the quantized channel response function when the packet is a first feedback packet sent to the transmitter or a first feedback packet sent after a channel interruption, and includes a quantized residual value of the channel response function otherwise, and dequantizes the quantized channel response function to provide a channel response function, and wherein the channel response function is an estimate of the channel response function, wherein the estimate of the channel response function is represented by N complex numbers, wherein the channel response function is represented by M complex numbers, and wherein N is less than M. - View Dependent Claims (21, 22)
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Specification