System and method for blind channel estimation and coherent differential equalization in an orthogonal frequency division multiplexing (ofdm) receiver

Patent metadata

Field	Value
Publication number	US-2024031203-A1
Application number	US-202318212608-A
Country	US
Kind code	A1
Filing date	Jun 21, 2023
Priority date	Dec 17, 2020
Publication date	Jan 25, 2024
Grant date	—

Abstract

In one aspect, an apparatus includes: a fast Fourier transform (FFT) engine to receive and convert a plurality of orthogonal frequency division multiplexing (OFDM) samples into a plurality of frequency carriers; a detector coupled to the FFT engine to determine a channel estimate for a first frequency carrier using a first channel estimate for the first frequency carrier and a plurality of other channel estimates, each of the plurality of other channel estimates for one of a plurality of neighboring frequency carriers within an evaluation window, and determine a log likelihood ratio (LLR) for the first frequency carrier using the channel estimate for the first frequency carrier; and a decoder coupled to the detector to decode a first OFDM symbol comprising the first frequency carrier using the LLR for the first frequency carrier.

First claim

1 . (canceled)

2 . A wireless receiver comprising:
a front end circuit to receive and process radio frequency signals into frequency domain data; a detector configured, based on the frequency domain data, to determine a channel estimate for a first frequency carrier using a first channel estimate for the first frequency carrier and one or more other channel estimates, each of the one or more other channel estimates for one of one or more neighboring frequency carriers within an evaluation window, the detector further configured to determine a soft decision for the first frequency carrier using the channel estimate for the first frequency carrier; and a decoder coupled to the detector and configured to decode encoded message information in the frequency domain data using the soft decision.

3 . The wireless receiver of claim 2 wherein the detector is further configured to determine the channel estimate for the first frequency carrier by calculating an average using the first channel estimate and the one or more other channel estimates.

4 . The wireless receiver of claim 2 wherein the soft decision is a log likelihood ratio.

5 . The wireless receiver of claim 3 wherein the evaluation window includes a first plurality of frequency carriers of a first orthogonal frequency division multiplexing symbol and a second plurality of frequency carriers of a second orthogonal frequency division multiplexing symbol adjacent to the first orthogonal frequency division multiplexing symbol.

6 . The wireless receiver of claim 2 wherein the soft decision includes a log likelihood ratio, and the detector is further configured to:
calculate a plurality of metrics for the first frequency carrier and the one or more neighboring frequency carriers within the evaluation window; and
determine the log likelihood ratio for a pair of frequency carriers including the first frequency carrier and a second frequency carrier based at least in part on the plurality of metrics.

7 . The wireless receiver of claim 5 wherein the detector includes:
a channel estimator configured to generate a plurality of channel estimates for the first frequency carrier, the plurality of channel estimates including the first channel estimate; and
a channel estimation smoother configured to determine the channel estimate for the first frequency carrier using the first channel estimate and the one or more other channel estimates.

8 . The wireless receiver of claim 2 wherein the detector and the decoder are implemented in a programmable controller.

9 . The wireless receiver of claim 2 wherein the detector and the decoder are implemented in dedicated hardware circuitry.

10 . The wireless receiver of claim 2 wherein the decoder is configured to perform coherent demodulation for a differentially encoded quadrature phase shift keying orthogonal frequency division multiplexing symbol.

11 . A method of operating a wireless receiver comprising:
receiving radio frequency signals with a front end circuit of the wireless receiver, and converting the radio frequency signals into frequency domain data; determining, with processing circuitry of the wireless receiver, based on the frequency domain data, a channel estimate for a first frequency carrier using a first channel estimate for the first frequency carrier and one or more other channel estimates, each of the one or more other channel estimates for one of one or more neighboring frequency carriers within an evaluation window; determining, with the processing circuitry, a log likelihood ratio for the first frequency carrier using the channel estimate for the first frequency carrier; and decoding encoded message information in the frequency domain data using the log likelihood ratio.

12 . The method of claim 11 wherein determining the channel estimate for the first frequency carrier includes calculating an average using the first channel estimate and the one or more other channel estimates.

13 . The method of claim 12 wherein the evaluation window includes a first plurality of frequency carriers of a first orthogonal frequency division multiplexing symbol and a second plurality of frequency carriers of a second orthogonal frequency division multiplexing symbol adjacent to the first orthogonal frequency division multiplexing symbol.

14 . The method of claim 11 claim wherein decoding encoded message information in the frequency domain data using the log likelihood ratio includes performing coherent demodulation for a differentially encoded quadrature phase shift keying orthogonal frequency division multiplexing symbol.

15 . A wireless receiver comprising:
a front end circuit to receive and process radio frequency signals into frequency domain data; a detector configured, based on the frequency domain data, to determine a plurality of channel estimates within an evaluation window having a plurality of frequency carriers including a first frequency carrier, each of the plurality of channel estimates for one of the plurality of frequency carriers, the detector further configured to calculate a plurality of metrics for each of the plurality of frequency carriers using at least some of the plurality of channel estimates, and to determine a soft decision for the first frequency carrier based at least in part on the plurality of metrics; and a decoder coupled to the detector to decode encoded message information in the frequency domain data using the soft decision for the first frequency carrier.

16 . The wireless receiver of claim 15 wherein the detector is further configured to determine a first channel estimate for the first frequency carrier by calculating an average of an initial channel estimate for the first frequency carrier and initial channel estimates for a plurality of other frequency carriers of the plurality of frequency carriers.

17 . The wireless receiver of claim 16 wherein the initial channel estimate is a channel estimate of the plurality of channel estimates closest to the initial channel estimate.

18 . The wireless receiver of claim 15 wherein the detector further includes a buffer configured to store the plurality of metrics.

19 . The wireless receiver of claim 15 wherein the detector and the decoder are implemented in a programmable controller.

20 . The wireless receiver of claim 15 wherein the detector and the decoder are implemented in dedicated hardware circuitry.

21 . The wireless receiver of claim 15 wherein the decoder is configured to perform coherent demodulation for a differentially encoded quadrature phase shift keying orthogonal frequency division multiplexing symbol.

Assignees

• Skyworks Solutions Inc

Inventors

• Kleinerman Alexander
• Wallace Bradley Arthur

Classifications

• H04L25/0238 Primary

  using blind estimation · CPC title

• H04L27/2636

  with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM] · CPC title

• H04L25/0204

  of multiple channels · CPC title

• H04L25/067

  providing soft decisions, i.e. decisions together with an estimate of reliability (H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178) · CPC title

• H04L25/0236

  using estimation of the other symbols · CPC title