Radio receiver with frequency segment offset compensation and related methods
Aspects of this disclosure relate to frequency offset compensation in a radio receiver. In embodiments of the disclosure, a frequency domain orthogonal frequency-division multiplexing signal can be received, and a phase error offset in individual frequency segments of the frequency domain orthogonal frequency-division multiplexing signal can be compensated for based on estimates of the phase error offset for the individual frequency segments. Related radio receivers and radio systems are disclosed.
1 . A method of frequency offset compensation in a radio receiver, the method comprising:
generating, in the radio receiver, an estimate of a carrier frequency offset in a time domain orthogonal frequency-division multiplexing signal based on processing the time domain orthogonal frequency-division multiplexing signal;
compensating, using a first compensation loop in the radio receiver, for the carrier frequency offset in the time domain orthogonal frequency-division multiplexing signal based on the estimate of the carrier frequency offset, the first compensation loop including a first loop filter;
generating a frequency domain orthogonal frequency-division multiplexing signal in the radio receiver from the time domain orthogonal frequency-division multiplexing signal; and
compensating, using a second compensation loop in the radio receiver, for a phase error offset in individual frequency segments of the frequency domain orthogonal frequency-division multiplexing signal based on estimates of the phase error offset for the individual frequency segments, the second compensation loop including a plurality of loop filters each having a longer time constant than the first loop filter.
2 . The method of claim 1 further comprising generating the estimates of the phase error offset for the individual frequency segments with a plurality of phase error offset estimation circuits, each of the plurality of phase error offset estimation circuits being associated with a respective frequency segment of the individual frequency segments.
3 . The method of claim 2 further comprising filtering the estimates of the phase error offset with respective loop filters of the plurality of loop filters, the compensating being based on outputs of the plurality of loop filters.
4 . The method of claim 1 wherein the compensating for the phase error offset is applied before equalizing the frequency domain orthogonal frequency-division multiplexing signal.
5 . The method of claim 1 further comprising generating the estimates of the phase error offset using average phase error estimation.
6 . The method of claim 1 wherein the processing the time domain orthogonal frequency-division multiplexing signal includes cyclic prefix correlation.
7 . The method of claim 1 further comprising storing time domain orthogonal frequency-division multiplexing symbols in a buffer, the buffer having an output coupled to an input of a Fourier transform engine that generates the frequency domain orthogonal frequency-division multiplexing signal.
8 . The method of claim 1 wherein the frequency domain orthogonal frequency-division multiplexing signal is a Digital Audio Broadcasting signal.
9 . A radio receiver with frequency offset compensation, the radio receiver comprising:
a first compensation loop configured to receive a time domain orthogonal frequency-division multiplexing signal and to compensate for a carrier frequency offset in the time domain orthogonal frequency-division multiplexing signal, the first compensation loop including a carrier frequency offset estimation circuit and a first loop filter;
a Fourier transform engine configured to convert the time domain orthogonal frequency-division multiplexing signal into frequency domain orthogonal frequency-division multiplexing signal; and
a second compensation loop configured to apply phase error offset compensation to individual frequency segments of the frequency domain orthogonal frequency-division multiplexing signal, the second compensation loop including a plurality of phase error offset estimation circuits and a plurality of loop filters, the plurality of loop filters each having a longer time constant than the first loop filter.
10 . The radio receiver of claim 9 further comprising a plurality of phase rotators and an equalizer, the plurality of phase rotators being in signal paths from the Fourier transform engine to the equalizer, and the plurality of phase rotators being connected to outputs of the plurality of loop filters.
11 . The radio receiver of claim 10 wherein the plurality of phase error offset estimation circuits are in signal paths between the equalizer and the plurality of loop filters.
12 . The radio receiver of claim 9 wherein the frequency domain orthogonal frequency-division multiplexing signal is a Digital Audio Broadcasting signal.
13 . The radio receiver of claim 9 further comprising a buffer configured to store time domain orthogonal frequency-division multiplexing symbols, the buffer having an output coupled to an input of the Fourier transform engine.
14 . The radio receiver of claim 9 wherein the plurality of phase error offset estimation circuits includes at least 4 phase error offset estimation circuits.
15 . The radio receiver of claim 9 wherein phase error offset in the frequency domain orthogonal frequency-division multiplexing signal is frequency selective.
16 . The radio receiver of claim 9 wherein the carrier frequency offset estimation circuit is configured to generate an estimate of the carrier frequency offset based on cyclic prefix correlation.
17 . A radio system with frequency offset compensation and phase error compensation, the radio system comprising:
at least one antenna configured to receive a radio signal, the radio signal being an orthogonal frequency-division multiplexing signal; and
a radio receiver including a first compensation loop and a second compensation loop, the first compensation loop including a first loop filter, the first compensation loop configured receive a time domain samples of the radio signal and to compensate for a carrier frequency offset using time domain circuitry, the second compensation loop including a plurality of loop filters each having a longer time constant than the first loop filter, and the second compensation loop configured to apply phase offset compensation for individual frequency segments of the radio signal in frequency domain circuitry.
18 . The radio system of claim 17 further comprising a speaker in communication with the radio receiver.
19 . The radio system of claim 17 wherein the first compensation loop includes a carrier frequency offset estimation circuit configured to generate an estimate of the carrier frequency offset based on cyclic prefix correlation.