Adaptive filter for channel estimation with adaptive step-size
AssigneeST-Ericsson SA
InventorStefan Mueller-Weinfurtner
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Abstract
A receiving apparatus for a digital mobile communication system comprises an adaptive filter for filtering an input signal. A step-size parameter chosen for the adaption of filter coefficients of the adaptive filter is computed from a variation of the filter coefficients used by the adaptive filter. This facilitates an indirect measure for the channel variation so that a good reception quality over a wide range of user velocities may be enabled in contrast to a system design based on a compromise step-size parameter being optimum for one velocity only.
Claims15
An adaptive filter for filtering an input signal, the filter comprising:
- a filter coefficients storage unit configured to store filter coefficients;
- a filter coefficients determination unit configured to determining adapted filter coefficients based on the filter coefficients, an error signal and a step-size parameter;
- and
- a step-size parameter control unit configured:
- to determine a channel variation quantity based:
- on a variation of a filter coefficient stored in the filter coefficient storage unit;
- and
- on an auxiliary quantity based on a scalar product of a vector of filter coefficients from a first timing for the auxiliary quantity and a vector of filter coefficients from a second timing for the auxiliary quantity;
- and
- to determine the step-size parameter based on the channel variation quantity.
A system, comprising:
- a signal processing unit;
- and
- an adaptive filter coupled to the signal processing unit and having:
- a filter coefficients storage unit configured to store filter coefficients;
- a filter coefficients determination unit configured to determining adapted filter coefficients based on the filter coefficients, an error signal and a step-size parameter;
- and
- a step-size parameter control unit configured:
- to determine a channel variation quantity based:
- on a variation of a filter coefficient stored in the filter coefficient storage unit;
- and
- on an auxiliary quantity based on a scalar product of a vector of filter coefficients from a first timing for the auxiliary quantity and a vector of filter coefficients from a second timing for the auxiliary quantity;
- and
- to determine the step-size parameter based on the channel variation quantity.
An adaptive method for filtering an input signal in a filter, the method comprising:
- determining adapted filter coefficients based on actual filter coefficients, an error signal, and a step-size parameter;
- determining a channel variation quantity based:
- on a variation of a filter coefficient;
- and
- on an auxiliary quantity based on a scalar product of a vector of filter coefficients from a first timing for the auxiliary quantity and a vector of filter coefficients from a second timing for the auxiliary quantity;
- determining the step-size parameter based on the channel variation quantity.
A non-transitory computer readable memory medium storing instructions that, when executed, cause a computing device to implement a method of filtering an input signal, the method comprising:
- determining adapted filter coefficients based on actual filter coefficients, an error signal, and a step-size parameter;
- determining a channel variation quantity based:
- on a variation of a filter coefficient;
- and
- on an auxiliary quantity based on a scalar product of a vector of filter coefficients from a first timing for the auxiliary quantity and a vector of filter coefficients from a second timing for the auxiliary quantity;
- determining the step-size parameter based on the channel variation quantity.
Dependencies are inferred from the claim text.