A method for cartesian (IQ) to polar phase conversion includes: converting a first input value into a first absolute value, and a second input value into a second absolute value; converting the first absolute value into a first logarithmic value by calculating a scaled logarithmic value of the first absolute value, and the second absolute value into a second logarithmic value by calculating a scaled logarithmic value of the second absolute value; subtracting the first logarithmic value from the second logarithmic value, to provide a subtract value; and selecting a phase value from a plurality of phase values stored in a storage unit. Each of the plurality of phase values corresponds to a respective index value, and the phase value is selected taking the subtract value as the index value.

Embodiments of the present disclosure relate to a method and apparatus for reducing storage space of a parameter table. The method may include: storing the parameter table in a lookup table system configured to compute an output value of a non-linear function according to an input value of the non-linear function, the parameter table including only an index value associated with an input value on one side of a median in a domain of the non-linear function and a parameter value corresponding to the index value; determining, by using a corresponding relationship between the index value associated with the input value on one side and the parameter value corresponding to the index value, a parameter value corresponding to an index value associated with an input value on the other side; and computing the output value by using the input value on the other side and the determined corresponding parameter value.

Embodiments of the present disclosure relate to a method and apparatus for reducing storage space of a parameter table. The method may include: storing the parameter table in a lookup table system configured to compute an output value of a non-linear function according to an input value of the non-linear function, the parameter table including only an index value associated with an input value on one side of a median in a domain of the non-linear function and a parameter value corresponding to the index value;

determining, by using a corresponding relationship between the index value associated with the input value on one side and the parameter value corresponding to the index value, a parameter value corresponding to an index value associated with an input value on the other side; and computing the output value by using the input value on the other side and the determined corresponding parameter value.

A method for cartesian (IQ) to polar phase conversion includes: converting a first input value into a first absolute value, and a second input value into a second absolute value; converting the first absolute value into a first logarithmic value by calculating a scaled logarithmic value of the first absolute value, and the second absolute value into a second logarithmic value by calculating a scaled logarithmic value of the second absolute value; subtracting the first logarithmic value from the second logarithmic value, to provide a subtract value; and selecting a phase value from a plurality of phase values stored in a storage unit. Each of the plurality of phase values corresponds to a respective index value, and the phase value is selected taking the subtract value as the index value.