Pilot-less noise estimation
AssigneeCisco Technology, Inc.
InventorsHang Jin, Koen Van Renterghem, Richard Meller, Denis Downey
Life of this patent
Estimating the term…
Abstract
Presented herein are pilot-less noise estimation techniques that utilize a correlation between attributes of a received signal and the noise to generate signal-to-noise ratio (SNR) estimate for the signal. More specifically, an interval of a digital signal is received a log-likelihood ratio (LLR) value is calculated for a plurality of bits in the interval of the signal. A scalar value that relates to a distribution of the calculated LLR values is computed. The SNR for the interval of the signal is determined based on a predetermined correlation between the scalar value and noise within the received interval of the signal.
Claims20
A method comprising:
- receiving a digital signal comprising a plurality of symbols transmitted over a communication channel, wherein the plurality of symbols each have a least significant bit and a second least significant bit;
- calculating a log-likelihood ratio (LLR) value for a plurality of bits within an interval of the signal by calculating an LLR value for either the least significant bit or the second least significant bit of each of a plurality of symbols in an interval, or for both the least significant bit and the second least significant bit of the plurality of symbols in the interval;
- computing a scalar value that relates to a statistical distribution of the calculated LLR values;
- and
- determining a signal-to-noise ratio (SNR) for the interval of the signal based on a predetermined correlation between the scalar value and noise within the interval of the signal.
An apparatus comprising:
- an interface unit configured to receive a digital signal comprising a plurality of symbols transmitted over a communication channel, wherein the plurality of symbols each have a least significant bit and a second least significant bit;
- and
- a processor coupled to the interface unit, and configured to:
- calculate a log-likelihood ratio (LLR) value for a plurality of bits within an interval of the signal by calculating an LLR value for either the least significant bit or the second least significant bit of each of a plurality of symbols in an interval, or for both the least significant bit and the second least significant bit of the plurality of symbols in the interval,
- compute a scalar value that relates to a statistical distribution of the calculated LLR values, and
- determine a signal-to-noise ratio (SNR) for the interval of the signal based on a predetermined correlation between the scalar value and noise within the interval of the signal.
An apparatus comprising:
- a receiver configured to receive a digital signal comprising a plurality of symbols transmitted over a communication channel, wherein the plurality of symbols each have a least significant bit and a second least significant bit;
- and
- a Low-Density Parity-Check (LDPC) decoder configured to:
- calculate a log-likelihood ratio (LLR) value for a plurality of bits within an interval of the signal by calculating an LLR value for either the least significant bit or the second least significant bit of each of a plurality of symbols in an interval, or for both the least significant bit and the second least significant bit of the plurality of symbols in the interval;
- calculate a standard deviation of the LLR values, wherein the standard deviation relates to a statistical distribution of the calculated LLR values;
- and
- determine a signal-to-noise ratio (SNR) for the interval of the signal based on a predetermined correlation between the standard deviation and noise within the interval of the signal.
Dependencies are inferred from the claim text.