Baseband predistortion method for multicarrier transmitters
AssigneeNokia Corporation
InventorTommi Ylamurto
Life of this patent
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Abstract
A multicarrier transmitter is shown having an embodiment of the invention. Sampling of modulated and amplified signals may be done to obtain energy values for four or more symbols. Combining the energy values with the baseband in-phase and quadrature signals of the multiple carriers may result in a set of imbalance parameters, which are subsequently stored. Later baseband in-hase and quadrature signals may be predistorted or compensated by applying the stored imbalance parameters to produce new compensated baseband in-phase and compensated baseband quadrature signals, which may be suitable for input to an inverse fast fourrier transform (IFFT) block.
Claims7
A method for providing a data symbol having a first quadrature compensated data symbol (FQCDS), second quadrature compensated data symbol (SQCDS), a first in-phase compensated data symbol (FICDS) and a second in-phase compensated data symbol (SICDS) to an inverse fast fourrier transform (IFFT) of a multicarrier quadrature modulator having an amplifier, wherein a first subcarrier data symbol and a second subcarrier data symbol are available from a mapper and an alpha, epsilon and gain are predetermined comprising the steps of:
- first quadrature compensating the data symbol based on the alpha, epsilon and gain to produce a FQCDS;
- second quadrature compensating the data symbol based on the alpha, epsilon and gain to produce a SQCDS;
- first in-phase compensating the data symbol based on the alpha, epsilon and gain to produce a FICDS;
- and
- second in-phase compensating the data symbol based on the alpha, epsilon and gain to produce a SICDS.
A method for providing a first quadrature compensated data symbol (FQCDS), second quadrature compensated data symbol (SQCDS), a first in-phase compensated data symbol (FICDS) and a second in-phase compensated data symbol (SICDS)to an inverse fast fourrier transform (IFFT) of a multicarrier quadrature modulator having an amplifier, wherein at least four transmitted symbol are available from the amplifier and at least four data symbols and a next data symbol are available from a mapper comprising the steps of:
- a) calculating the energy of at least four transmitted symbols;
- b) calculating a alpha, epsilon and gain based on the energy of the at least four transmitted symbols and at least four data symbols;
- c) storing the alpha, epsilon and gain;
- d) first quadrature compensating the next data symbol first quadrature subcarrier based on the alpha, epsilon and gain to produce a FQCDS;
- e) second quadrature compensating the next data symbol second quadrature subcarrier based on the alpha, epsilon and gain to produce a SQCDS;
- f) first in-phase compensating the next data symbol first in-phase subcarrier based on the alpha, epsilon and gain to produce a FICDS;
- g) second in-phase compensating the next data symbol second in-phase subcarrier based on the alpha, epsilon and gain to produce a SICDS;
- and
- h) repeating steps a, b and c wherein the at least four transmitted symbols include the next transmitted data symbol and the at least four data symbols include the next data symbol.
An apparatus for providing a first quadrature compensated data symbol (FQCDS), second quadrature compensated data symbol (SQCDS), a first in-phase compensated data symbol (FICDS) and a second in-phase compensated data symbol (SICDS)to an inverse fast fourrier transform (IFFT) of a multicarrier quadrature modulator having an amplifier, wherein at least four transmitted symbol are available from the amplifier and at least four data symbols and a next data symbol are available from a mapper comprising:
- a) means for calculating the energy of at least four transmitted symbols;
- b) means for calculating a alpha, epsilon and gain based on the energy of the at least four transmitted symbols and at least four data symbols;
- c) means for storing the alpha, epsilon and gain;
- d) means for first quadrature compensating the next data symbol first quadrature subcarrier based on the alpha, epsilon and gain to produce a FQCDS;
- e) means for second quadrature compensating the next data symbol second quadrature subcarrier based on the alpha, epsilon and gain to produce a SQCDS;
- f) means for first in-phase compensating the next data symbol first in-phase subcarrier based on the alpha, epsilon and gain to produce a FICDS;
- g) means for second in-phase compensating the next data symbol second in-phase subcarrier based on the alpha, epsilon and gain to produce a SICDS;
- and
- h) means for repeating steps a, b and c wherein the at least four transmitted symbols include the next transmitted data symbol and the at least four data symbols include the next data symbol.
Dependencies are inferred from the claim text.