Drift Robust Non-Coherent Demodulation Scheme
AssigneeApple Inc.
InventorYuval Avner
Life of this patent
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Abstract
This document describes techniques for performing non-coherent demodulation of a differentially modulated signal in a drift robust manner. A differentially modulated signal, including a plurality of symbols, may be received. Non-coherent demodulation of the differentially modulated signal may be performed. The non-coherent demodulation may include performing noise prediction using a high-pass filtered estimated error signal associated with the differentially modulated signal. In some embodiments, frequency offset estimation to reduce frequency offset of the differentially modulated signal may also be performed as part of the non-coherent demodulation.
Claims20
A wireless device, comprising:
- an antenna;
- a radio operatively coupled to the antenna;
- and
- a processing element operatively coupled to the radio;
- wherein the wireless device is configured to:
- wirelessly receive a differentially modulated signal comprising a plurality of symbols;
- and
- demodulate the differentially modulated signal,
- wherein the wireless device comprises a noise prediction loop configured to reduce noise characteristics of the differentially modulated signal, wherein the noise prediction loop performs noise prediction for a next symbol of the differentially modulated signal based at least in part on a high-pass filtered error signal associated with a current symbol of the differentially modulated signal and modifies the next symbol based at least in part on a result of the noise prediction, wherein the noise prediction is based at least in part upon a difference between an ideal angular domain result and an angular domain result of subtraction of a previous symbol from the current symbol.
A method, comprising:
- at a wireless device:
- receiving a differentially modulated signal;
- and
- performing non-coherent demodulation of the differentially modulated signal,
- wherein the non-coherent demodulation comprises performing noise prediction using a high pass filtered estimated error signal associated with the differentially modulated signal,
- wherein the noise prediction is based at least in part upon a difference between an ideal angular domain result and an angular domain result of subtraction of a previous symbol from the current symbol.
An integrated circuit, comprising:
- a symbol value selection circuit portion configured to determine symbol values for symbols of a differentially modulated signal;
- an error estimation circuit portion configured to calculate an estimated error signal for symbols of the differentially modulated signal;
- a high pass filtering circuit portion configured to perform high pass filtering of the estimated error signal;
- and
- a noise prediction circuit portion configured to perform noise prediction based on the estimated error signal after the high pass filtering,
- wherein the noise prediction is based at least in part upon a difference between an ideal angular domain result and an angular domain result of subtraction of a previous symbol from the current symbol, and
- wherein the noise prediction circuit portion is further configured to feed back a result of the noise prediction into the differentially modulated signal to whiten noise effects in the differentially modulated signal.
Dependencies are inferred from the claim text.