Adaptive predistortion for a transmit system with gain, phase and delay adjustments
AssigneeZarbana Digital Fund LLC
InventorAryan Saed
Life of this patent
Estimating the term…
Abstract
Systems and methods relating to the provision of gain, phase and delay adjustments to signals to be used by a predistortion subsystem. A portion of an input signal is delayed by delay elements prior to being received by the predistortion subsystem. The delayed input signal portion is also received by a feedback signal processing subsystem that adjusts the gain and phase of the feedback signal based on the delayed input signal portion. The adjusted feedback signal is used, along with the delayed portion of the input signal, to determine an appropriate predistortion modification to be applied to the input signal.
Claims48
A system for processing an input signal, the system comprising:
- an adaptive predistortion subsystem for receiving said input signal and for producing a predistorted signal by applying a deliberate predistortion to said input signal;
- a signal processing subsystem receiving and processing said predistorted signal and producing a system output signal:
- a feedback signal processing subsystem for receiving and processing a feedback signal derived from said system output signal;
- and
- a delay subsystem for providing a delay to a replica of said input signal to produce a delayed signal, said delayed signal being used by said adaptive predistortion subsystem and said feedback processing subsystem,
- wherein
- said adaptive predistortion subsystem distorts said input signal to compensate for distortions in said system output signal;
- said signal processing subsystem decomposes said predistorted signal into separate components, each of said separate components being processed separately;
- said processing subsystem combines said components after processing to produce said system output signal;
- an output of said feedback processing subsystem being used by said adaptive predistortion subsystem;
- said deliberate predistortion applied to said input signal by said adaptive predistortion subsystem to produce said predistorted signal is adjusted based on said system output signal.
A method of processing an input signal to produce a system output signal, the method comprising:
- a) receiving said input signal;
- b) applying a deliberate predistortion to said input signal to result in a predistorted signal;
- c) decomposing said predistorted signal into at least two component signals;
- d) combining said at least two component signals to produce said system output signal;
- e) adjusting said deliberate predistortion based on said system output signal
- f) concurrent with steps b) -e), executing the following steps:
- f1) delaying a replica of said input signal;
- f2) diverting a diverted replica of said system output signal to a feedback path;
- f3) processing said diverted replica to produce a corrected version of said diverted replica;
- and
- f4) determining said deliberate predistortion using said corrected version and said replica of said input signal.
An adaptive predistortion subsystem for use with a signal processing system which produces a system output signal, the predistortion subsystem comprising:
- determining means for determining a deliberate predistortion to be applied to an input signal;
- adjustment means for applying said deliberate predistortion to said input signal;
- update means for periodically updating said determining means based on characteristics of said system output signal
- wherein said adaptive predistortion subsystem uses
- an output of a delay subsystem for delaying said input signal and
- an output of a feedback processing subsystem for processing a feedback signal derived from said system output signal
- to determine said deliberate predistortion.
A method of initializing a phase correction to be applied to a feedback signal, said feedback signal to be used in determining a deliberate predistortion for a signal processing system, the method comprising:
- a) initiating a coarse delay search
- b) selecting a time window of W samples of said feedback signal and an input signal with a predetermined sample delay increments of δ between samples
- c) calculating an inner product Pδ by performing a complex multiply and accumulate process for the W samples in the time window
- d) storing a maximum |Pδ| found
- e) repeating steps c) and d) for subsequent time windows and incrementing δ by a predetermined amount for each time window
- f) repeating steps b)-e) for a fine delay search using factional sample increments to cover a predetermined delay range, said delay range being centered on a maximum delay increment δmax found during said coarse delay search.
Dependencies are inferred from the claim text.