Generating higher order modulation using QPSK modulations

1. An apparatus, comprising:

a receiver configured to receive a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation, wherein the apparatus is a first quadrature phase shift keying (QPSK) modulating apparatus of two QPSK modulating apparatuses;

a first mapping unit configured to map the symbols of the higher order modulation to first constellation points of the QPSK modulating apparatus in order to provide an output signal of the first QPSK modulating apparatus which is added to an output signal of a second QPSK modulating apparatus of the two QPSK modulating apparatuses, in order to generate the constellation points of the higher order modulation; and

a first weighting unit configured to apply first weights when mapping the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus,

wherein the second QPSK modulating apparatus comprises a second mapping unit configured to map the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and output the output signal of the second QPSK modulating apparatus corresponding to the second constellation points, and a second weighting unit configured to apply second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus,

wherein the first weights of the first QPSK modulating apparatus are two times higher than the second weights or half of the second weights applied by the second QPSK modulating apparatus.

2. The apparatus according to claim 1 , wherein the first mapping unit is configured to refer to a table relating the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus.

3. The apparatus according to claim 1 ,

wherein the higher order modulation is a 16QAM modulation, wherein a first constellation point of the first QPSK modulating apparatus, to which a symbol of the 16QAM modulation is mapped, is located at a same position in a constellation diagram as a corresponding constellation point of the 16QAM modulation when an origin of the constellation diagram of the first QPSK modulating apparatus is placed at a center of those constellation points of the 16QAM modulation which belong to a quadrant in which a second constellation point of the second QPSK modulating apparatus is located.

4. A system, comprising:

a first quadrature phase shift keying (QPSK) modulating apparatus comprising a first receiver configured to receive a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation, and

a first mapping unit configured to map the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus and outputting an output signal of the first QPSK modulating apparatus corresponding to the first constellation points, and

a first weighting unit configured to apply first weights when mapping the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus;

a second QPSK modulating apparatus comprising

a second receiver configured to receive the complex sequence of binary digits corresponding to the symbols of the higher order modulation, the symbols corresponding to the constellation points of the higher order modulation, and

a second mapping unit configured to map the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputting an output signal of the second QPSK modulating apparatus corresponding to the second constellation points; and

a second weighting unit configured to apply second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus, the first weights being half of the second weights or the first weights being two times higher than the second weights; and

an adding unit configured to add the output signals of the first and second QPSK modulating apparatuses to generate the constellation points of the higher order modulation.

5. The system according to claim 4 , comprising:

a generator configured to generate a mapping table relating the constellation points of the higher order modulation to the first and second constellation points of the first and second QPSK modulating apparatuses, wherein the first and second mapping units are configured to refer to the mapping table for mapping the symbols of the higher order modulation to the first and second constellation points, respectively.

6. A method for a first QPSK modulating apparatus of two QPSK modulating apparatuses, the first QPSK modulating apparatus comprising a first mapping unit and a first weighting unit, a second QPSK modulating apparatus of the two QPSK modulating apparatuses comprising a second mapping unit and a second weighting unit, the method comprising:

receiving, a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation;

mapping, at the first mapping unit, the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus in order to provide an output signal of the first QPSK modulating apparatus which is added to an output signal of the second QPSK modulating apparatus, in order to generate the constellation points of the higher order modulation; and

applying weights, at the first weighting unit, when mapping the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus,

wherein the second mapping unit of the second QPSK modulating apparatus maps the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputs the output signal of the second QPSK modulating apparatus corresponding to the second constellation points, and the second weighting unit of the second QPSK modulating apparatus applies second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus,

wherein the first weights are half of the second weights or two times higher than the second weights.

7. The method according to claim 6 , comprising:

referring to a table relating the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus when mapping the symbols at the first mapping unit.

8. The method according to claim 6 , wherein the higher order modulation is a 16QAM modulation, wherein a first constellation point of the first QPSK modulating apparatus, to which a symbol of the 16QAM modulation is mapped, is located in a same quadrant of a constellation diagram as a corresponding constellation point of the 16QAM modulation.

9. The method according to claim 6 , wherein the higher order modulation is a 16QAM modulation, wherein a first constellation point of the first QPSK modulating apparatus, to which a symbol of the 16QAM modulation is mapped, is located at a same position in a constellation diagram as a corresponding constellation point of the 16QAM modulation when an origin of the constellation diagram of the first QPSK modulating apparatus is placed at a center of those constellation points of the 16QAM modulation which belong to a quadrant in which a second constellation point of the second QPSK modulating apparatus is located.

10. A method for a system comprising a first QPSK modulating apparatus and a second QPSK modulating apparatus, the first QPSK modulating apparatus comprising a first mapping unit and a first weighting unit, the second QPSK modulating apparatus comprising a second mapping unit and a second weighting unit, the method comprising:

receiving a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation;

mapping, at the first mapping unit, the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus and outputting an output signal of the first QPSK modulating apparatus corresponding to the first constellation points;

mapping, at the second mapping unit, the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputting an output signal of the second QPSK modulating apparatus corresponding to the second constellation points;

applying, at the first weighting unit, first weights when mapping the symbols of the higher order modulation to the first constellation points and applying, at the second weighting unit, the second weights when mapping the symbols of the higher order modulation to the second constellation points, the first weights being half of the second weights or the first weights being two times higher than the second weights; and

adding the output signals of the first and second QPSK modulating apparatuses to generate the constellation points of the higher order modulation.

11. A computer program embodied on a computer-readable medium, said program configured to control a computer to perform

a method for a first QPSK modulating apparatus of two QPSK modulating apparatuses, the first QPSK modulating apparatus comprising a first mapping unit and a first weighting unit, a second QPSK modulating apparatus of the two QPSK modulating apparatuses comprising a second mapping unit and a second weighting unit, the method comprising:

receiving a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation;

mapping, at the first mapping unit, the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus in order to provide an output signal of the first QPSK modulating apparatus which is added to an output signal of the second QPSK modulating apparatus, in order to generate the constellation points of the higher order modulation; and

applying weights, at the first weighting unit, when mapping the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus,

wherein the second mapping unit of the second QPSK modulating apparatus maps the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputs the output signal of the second QPSK modulating apparatus corresponding to the second constellation points, and the second weighting unit of the second QPSK modulating apparatus applies second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus,

wherein the first weights are half of the second weights or two times higher than the second weights.

12. The computer program according to claim 11 , wherein the computer program is loaded into an internal memory of the computer.

13. A computer program embodied on a computer-readable medium, said program configured to control a computer to perform:

a method for a system comprising a first QPSK modulating apparatus and a second QPSK modulating apparatus, the first QPSK modulating apparatus comprising a first mapping unit and a first weighting unit, the second QPSK modulating apparatus comprising a second mapping unit and a second weighting unit, the method comprising:

receiving a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation;

mapping, at the first mapping unit, the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus and outputting an output signal of the first QPSK modulating apparatus corresponding to the first constellation points;

mapping, at the second mapping unit, the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputting an output signal of the second QPSK modulating apparatus corresponding to the second constellation points;

applying, at the first weighting unit, first weights when mapping the symbols of the higher order modulation to the first constellation points and applying, at the second weighting unit, the second weights when mapping the symbols of the higher order modulation to the second constellation points, the first weights being half of the second weights or the first weights being two times higher than the second weights; and

adding the output signals of the first and second QPSK modulating apparatuses to generate the constellation points of the higher order modulation.

14. The computer program according to claim 13 , wherein the computer program is loaded into an internal memory of the computer.

15. An apparatus, comprising:

receiving means for receiving a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation, wherein the apparatus is a first quadrature phase shift keying (QPSK) modulating apparatus of two QPSK modulating apparatuses;

first mapping means for mapping the symbols of the higher order modulation to first constellation points of the QPSK modulating apparatus in order to provide an output signal of the first QPSK modulating apparatus which is added to an output signal of a second QPSK modulating apparatus of the two QPSK modulating apparatuses, in order to generate the constellation points of the higher order modulation; and

first weighting means for applying first weights when mapping the symbols of the 16QAM higher order modulation to the first constellation points of the first QPSK modulating apparatus,

wherein the second QPSK modulating apparatus comprises second mapping means for mapping the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputting the output signal of the second QPSK modulating apparatus corresponding to the second constellation points, and second weighting means for applying second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus,

wherein the first weights of the first QPSK modulating apparatus are two times higher than the second weights or half of the second weights applied by the second QPSK modulating apparatus.

16. A system, comprising:

a first quadrature phase shift keying (QPSK) modulating apparatus comprising

first receiving means for receiving a complex sequence of binary digits corresponding to symbols of a higher order modulation, the symbols corresponding to constellation points of the higher order modulation,

first mapping means for mapping the symbols of the higher order modulation to first constellation points of the first QPSK modulating apparatus and outputting an output signal of the first QPSK modulating apparatus corresponding to the first constellation points, and

first weighting means for applying first weights when mapping the symbols of the higher order modulation to the first constellation points of the first QPSK modulating apparatus;

a second QPSK modulating apparatus comprising

second receiving means for receiving the complex sequence of binary digits corresponding to the symbols of the higher order modulation, the symbols corresponding to the constellation points of the higher order modulation,

second mapping means for mapping the symbols of the higher order modulation to second constellation points of the second QPSK modulating apparatus and outputting an output signal of the second QPSK modulating apparatus corresponding to the second constellation points, and

second weighting means for applying second weights when mapping the symbols of the higher order modulation to the second constellation points of the second QPSK modulating apparatus, the first weights being half of the second weights or the first weights being two times higher than the second weights; and

adding means for adding the output signals of the first and second QPSK modulating apparatuses to generate the constellation points of the higher order modulation.