AFC wrap-around detection
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorKarin Engdahl
Life of this patent
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Abstract
A wrap-around event in an automatic frequency control (AFC) in a receiver in a communication system can be detected by performing AFC-like operations on one or more additional channel estimates of the strongest communication path. Once a wrap-around event is detected, a correct frequency reference can be restored by forcing the AFC into a high-speed mode of operation, which gives the AFC a chance to restore the correct frequency reference, or by applying a momentary frequency reference change.
Claims20
A method of detecting an automatic frequency control (AFC) wrap-around event based on a signal received through a communication channel, comprising the steps of:
- collecting, by a receiver, a first plurality of channel parameters;
- carrying out typical AFC computations using the first plurality of channel parameters;
- collecting, by the receiver, a second plurality of wrap-around channel parameters;
- carrying out wrap-around AFC computations using the second plurality of wrap-around channel parameters;
- and
- detecting the AFC wrap-around event based on results of the wrap-around AFC computations.
An apparatus for detecting wrap-around events based on signals received through a communication channel, comprising:
- a RAKE processor configured to generate correlated signals from a signal received through the communication channel;
- a channel estimator configured to generate channel parameters of the communication channel from the correlated signals, the channel parameters including a first plurality of channel parameters and a second plurality of wrap-around channel parameters;
- an automatic frequency controller (AFC) configured to generate at least one of a first phase angle φ and a first frequency error ferr based on the first plurality of channel parameters;
- and
- a wrap-around detector configured to generate at least one of a second wrap-around phase angle φwa and a second wrap-around frequency error ferrwa based on the second plurality of wrap-around channel parameters;
- wherein a wrap-around event is detected based on at least one of the second wrap-around angle signal and the second wrap-around control signal.
Dependencies are inferred from the claim text.