Channel estimation feedback in an orthogonal frequency division multiplexing system or the like
First Claim
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1. A system comprising:
- an access point including a transceiver configured to communicate via a wireless network; and
a mobile unit configured to communicate with the access point, the mobile unit including;
a transceiver; and
a channel estimation feedback encoder configured to;
quantize a channel response function of a signal received from the access point 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;
calculate a channel attenuation estimation to quantize the channel response function, wherein the channel attenuation estimation includes an estimate of time delay attenuation function of a magnitude of the time domain representation of the signal;
de-quantize the quantized values of the channel response function and to use the de-quantized values to calculate the residual value of the channel response function;
limit 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;
convert the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to said quantizing; and
generate a channel state information packet to be transmitted back to the access point, 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.
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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.
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Citations
18 Claims
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1. A system comprising:
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an access point including a transceiver configured to communicate via a wireless network; and a mobile unit configured to communicate with the access point, the mobile unit including; a transceiver; and a channel estimation feedback encoder configured to; quantize a channel response function of a signal received from the access point 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; calculate a channel attenuation estimation to quantize the channel response function, wherein the channel attenuation estimation includes an estimate of time delay attenuation function of a magnitude of the time domain representation of the signal; de-quantize the quantized values of the channel response function and to use the de-quantized values to calculate the residual value of the channel response function; limit 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; convert the signal from a frequency domain representation of the signal to a time domain representation of the signal prior to said quantizing; and generate a channel state information packet to be transmitted back to the access point, 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 (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification