Method for reducing power consumption when estimating timing errors in wireless signals
View Patent ↗A method and apparatus for low power timing recovery is provided. In an embodiment, different gains are used to estimate timing errors during different portions of the data packet. In an embodiment, timing errors are only estimated during known sequences of a data packet. In further embodiments, errors are initially estimated independently in a first portion of the data packet in order to determine a phase shift between the errors. In the second portion of the data packet, the total error is derived from one estimated error and the phase shift between the errors.
1. A radio frequency signal receiver, comprising:
one or more receiver clocks;
a first error estimator, configured to estimate a carrier frequency offset error for a received data packet during a first portion of the received data packet;
a first error corrector, configured to correct for the carrier frequency offset error in the received data packet;
a second error estimator, configured to estimate a sampling frequency offset error for the received data packet during the first portion of the received data packet;
a second error corrector, configured to correct for the sampling frequency offset error in the received data packet;
a phase shift calculator, configured to determine initial phases of the carrier frequency offset error and the sampling frequency offset error;
wherein one or more of the first error estimator and the second error estimator are further configured to operate during a second portion of the received data packet and estimate one or more components of a total timing error in the received data;
an error calculator, configured to determine an estimate of the total timing error based on the initial phases of the carrier frequency offset error, the initial phases of the sampling frequency offset error and the one or more components of the total timing error; and
a third error corrector, configured to correct for the total timing error in the received data packet.
2. The radio signal frequency receiver of claim 1 , wherein the first portion of the received data packet is the preamble of the received data packet and the second portion of the received data packet is the payload of the received data packet.
3. The radio signal frequency receiver of claim 1 , wherein:
the one or more components of the total timing error in the received data packet consists of the carrier frequency offset error; and
the error calculator calculates the total timing error by:
estimating the sampling frequency offset error based on its relationship to the carrier frequency offset error; and
combining the estimated carrier frequency offset error with the estimated sampling frequency offset error.
4. The radio signal frequency receiver of claim 1 , wherein:
the one or more components of the total timing error in the received data packet consists of the sampling frequency offset error; and
the error calculator calculates the total timing error by:
estimating the carrier frequency offset error based on its relationship to the sampling frequency offset error; and
combining the estimated sampling frequency offset error with the estimated carrier frequency offset error.
5. The radio signal frequency receiver of claim 1 , wherein:
the one or more components of the total timing error in the received data packet comprises the carrier frequency offset error and the sampling frequency offset error;
the first error estimator is configured to estimate the carrier frequency offset error at a first rate and the second error estimator is configured to estimate the sampling frequency offset error at a second rate;
wherein the first rate is greater than the second rate;
the error calculator determines the estimate of the total timing error in the received data packet by:
estimating the sampling frequency offset error based on its relationship to the carrier frequency offset error;
making corrections to the estimated sampling frequency offset error using the estimated sampling frequency offset error; and
combining the estimated carrier frequency offset error with the corrected sampling frequency offset error.
6. The radio signal frequency receiver of claim 1 :
wherein the second portion of the received data packet begins immediately after the phase shift calculator determines the initial phases of the carrier frequency offset error and the sampling frequency offset error.
7. The radio signal frequency receiver of claim 1 , wherein the one or more of the first error estimator and the second error estimator are further configured to operate only during one or more known portions of the second portion of the received data packet.
8. The radio signal frequency receiver of claim 1 , further comprising a gain selector, configured to cause the radio frequency signal receiver to use a first gain during the first portion of the received data packet and use a second gain during the second portion of the received data packet;
wherein the first gain is greater than the second gain.