Method and apparatus for timing recovery in an OFDM system
AssigneeXM Satellite Radio, Inc.
InventorJoseph Smallcomb
Life of this patent
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Abstract
A method (500) for timing recovery in an orthogonal frequency division multiplexing (OFDM) system includes the steps of detecting (502) a lack of a synchronization symbol and determining (504) a timing offset from calculating the average group delay across the subcarriers over multiple OFDM symbols. The timing offset is fed back (506) to a demodulator and the symbol timing is adjusted (508) based on the Average Group Delay phasor fed back to the demodulator.
Claims13
A method for timing recovery in an orthogonal frequency division multiplexing (OFDM) system, comprising the steps of:
- detecting a lack of a synchronization symbol;
- determining a timing offset from calculating the Average Group delay over a set of OFDM symbols;
- feeding back the timing offset to a demodulator;
- and
- adjusting the symbol timing based on the Average Group Delay fed back to the demodulator.
A method for timing recovery in an orthogonal frequency division multiplexing (OFDM) system, comprises:
- detecting a negative phase in a OFDM modulated signal;
- narrowing a search window for the synchronization symbol;
- and
- adjust timing to an earlier arriving signal detected by a synchronization symbol recovery detector.
A method for timing recovery in an orthogonal frequency division multiplexing (OFDM) system, comprises:
- detecting a negative phase;
- disabling a synchronization symbol recovery algorithm;
- and
- adjusting the phase until a non-negative phase is detected.
A digital receiver unit, comprising:
- a receiver;
- an orthogonal frequency division multiplexing demodulator;
- and
- a processor coupled to the receiver and the demodulator, wherein the processor is programmed to:
- detect a lack of a synchronization symbol;
- determine a phase offset from a set of OFDM symbols;
- feed back the phase offset to the demodulator;
- and
- adjust the symbol timing based on the phase offset fed back to the demodulator.
Dependencies are inferred from the claim text.