Method and apparatus for modulation and demodulation
One of the embodiments of the present invention relates to a method for modulation. The method comprises: providing a first bit sequence of continuous bits “1” or continuous bits “0” generating a second bit sequence by replacing, in each of a plurality of modulation intervals with a predetermined bit number, at least one bit of the first bit sequence at least one fixed position of the respective modulation interval with one information bit from an information bit sequence; and modulating the second bit sequence so as to generate a positioning packet with a modulated continuous wave signal for transmission. The embodiments further relate to a method for demodulation. Embodiments of the present invention also provide corresponding apparatuses and computer program products.
1. An apparatus, comprising:
at least one processor and at least one memory including computer program instructions, wherein the at least one memory and computer program instructions are configured to, with the at least one processor, cause the apparatus at least to:
provide a first bit sequence of continuous bits “1” or continuous bits “0”;
generate a second bit sequence by replacing, in each of a plurality of modulation intervals with a predetermined bit number N modulation _ interval , at least one bit of the first bit sequence at least one fixed position of the respective modulation interval with one information bit from an information bit sequence; and
modulate the second bit sequence so as to generate a positioning packet with a modulated continuous wave signal for transmission,
wherein N is an integer.
2. The apparatus according to claim 1 , wherein the predetermined bit number N modulation _ interval satisfies:
N modulation _ interval =n*L cw /N measurement _ points ,
where L cw denotes the length of the first sequence of continuous bits; N measurement _ points denotes the number of measurement points, at each of which positioning measurement is performed at receiving side based on the received modulated continuous wave signal by measuring phase differences among a plurality of different antenna elements; n denotes a predefined positive integer.
3. The apparatus according to claim 1 , wherein generate the second bit sequence comprises arrange bit positions of the replaced information bits and the measurement points such that only bits which belong to the continuous bits but not the replaced information bits will be used at the respective measurement points to perform the positioning measurement at receiving side.
4. The apparatus according to claim 1 , wherein generate the second bit sequence comprises flip the at least one bit in a modulation interval depending upon the value of a respective information bit.
5. The apparatus according to claim 1 , wherein modulate the second bit sequence comprises modulate the second bit sequence by a frequency-shift keying modulator, a phase-shift keying modulator, a pulse-amplitude modulation modulator or a quadrature amplitude modulation modulator.
6. An apparatus, comprising:
at least one processor and at least one memory including computer program instructions, wherein the at least one memory and computer program instructions are configured to, with the at least one processor, cause the apparatus at least to:
receive a positioning packet with a modulated continuous wave signal via a plurality of different antenna elements;
demodulate the modulated continuous wave signal to obtain a first bit sequence including a plurality of modulation intervals with a predetermined bit number N modulation _ interval , wherein at least one information bit occupies at least one fixed position in each of said plurality of modulation intervals and continuous bits “1” or continuous bits “0” occupy the other positions in the respective modulation intervals; and
perform concurrently, based on the modulated continuous wave signal, positioning measurement by measuring phase differences among the plurality of different antenna elements at each of a number N measurement _ points of measurement points,
wherein N is an integer.
7. The apparatus according to claim 6 , wherein the predetermined bit number N modulation _ interval satisfies:
N modulation _ interval =n*L cw /N measurement _ points ,
where L cw denotes the length of the first bit sequence of continuous bits; n denotes a predefined positive integer.
8. The apparatus according to claim 6 , wherein the measurement points and bit positions of the information bits are arranged such that only bits which belong to the continuous bits but not the information bits will be used at the respective measurement points to perform the positioning measurement.
9. The apparatus according to claim 6 , wherein demodulate the modulated continuous wave signal comprises demodulate the modulated continuous wave signal by a Gaussian frequency-shift keying demodulator.
10. The apparatus according to claim 6 , wherein the bit position of an information bit in a modulation interval and a respective measurement point are arranged such that the information bit is separated, by at least one bit, from a bit to be used at the respective measurement point to perform the positioning measurement, and further comprising at least one of:
apply phase compensation values c 0 , c 1 , c 2 , . . . , c i , . . . , c Nmeasurement _ point-1 to the positioning measurement at the respective measurement points; and
compute, in response to determining that there are two sequential bit flips in the first bit sequence between an (i−1) th measurement point and an i th measurement point, a phase compensation value c i to be applied to the positioning measurement according to:
c i =c i-1 +Pi, when the first bit sequence is composed of continuous bits “1” and the information bits,
c i =c 1-1 −Pi, when the first bit sequence is composed of continuous bits “0” and the information bits; and
compute, in response to determining that there is not any bit flip in the first bit sequence between an (i−1) th measurement point and an i th measurement point, a phase compensation value c i to be applied to the positioning measurement according to c i =c i-1 .
11. A method comprising:
receiving a positioning packet with a modulated continuous wave signal via a plurality of different antenna elements;
demodulating the modulated continuous wave signal to obtain a first bit sequence including a plurality of modulation intervals with a predetermined bit number N modulation _ interval , wherein at least one information bit occupies at least one fixed position in each of said plurality of modulation intervals and continuous bits “1” or continuous bits “0” occupy the other positions in the respective modulation intervals; and
performing concurrently, based on the modulated continuous wave signal, positioning measurement by measuring phase differences among the plurality of different antenna elements at each of a number N measurement _ points of measurement points,
wherein N is an integer.
12. The method according to claim 11 , wherein the predetermined bit number N modulation _ interval satisfies:
N modulation _ interval =n*L cw /N measurement _ points ,
where L cw denotes the length of the first bit sequence of continuous bits; n denotes a predefined positive integer.
13. The method according to claim 11 , wherein the measurement points and bit positions of the information bits are arranged such that only bits which belong to the continuous bits but not the information bits will be used at the respective measurement points to perform the positioning measurement.
14. The method according to claim 11 , wherein demodulating the modulated continuous wave signal comprises demodulating the modulated continuous wave signal by a Gaussian frequency-shift keying demodulator.
15. The method according to claim 11 , wherein the bit position of an information bit in a modulation interval and a respective measurement point are arranged such that the information bit is separated, by at least one bit, from a bit to be used at the respective measurement point to perform the positioning measurement, and further comprising at least one of:
applying phase compensation values c 0 , c 1 , c 2 , . . . , c i , . . . , c Nmeasurement _ point-1 to the positioning measurement at the respective measurement points; and
computing, in response to determining that there are two sequential bit flips in the first bit sequence between an (i−1) th measurement point and an i th measurement point, a phase compensation value c i to be applied to the positioning measurement according to:
c i =c i-1 +Pi, when the first bit sequence is composed of continuous bits “1” and the information bits,
c i =c i-1 −Pi, when the first bit sequence is composed of continuous bits “0” and the information bits; and
computing, in response to determining that there is not any bit flip in the first bit sequence between an (i−1) th measurement point and an i th measurement point, a phase compensation value c i to be applied to the positioning measurement according to c i =c i-1 .
16. A method, comprising:
providing a first bit sequence of continuous bits “1” or continuous bits “0”;
generating a second bit sequence by replacing, in each of a plurality of modulation intervals with a predetermined bit number N modulation _ interval , at least one bit of the first bit sequence at least one fixed position of the respective modulation interval with one information bit from an information bit sequence; and
modulating the second bit sequence so as to generate a positioning packet with a modulated continuous wave signal for transmission,
wherein N is an integer.
17. The method according to claim 16 , wherein the predetermined bit number N modulation _ interval satisfies:
N modulation _ interval =n*L cw /N measurement _ points ,
where L cw denotes the length of the first sequence of continuous bits; N measurement _ points denotes the number of measurement points, at each of which positioning measurement is performed at receiving side based on the received modulated continuous wave signal by measuring phase differences among a plurality of different antenna elements; n denotes a predefined positive integer.
18. The method according to claim 16 , wherein generating the second bit sequence comprises arranging bit positions of the replaced information bits and the measurement points such that only bits which belong to the continuous bits but not the replaced information bits will be used at the respective measurement points to perform the positioning measurement at receiving side.
19. The method according to claim 16 , wherein generating the second bit sequence comprises flipping the at least one bit in a modulation interval depending upon the value of a respective information bit.
20. The method according to claim 16 , wherein modulating the second bit sequence comprises modulating the second bit sequence by a frequency-shift keying modulator, a phase-shift keying modulator, a pulse-amplitude modulation modulator or a quadrature amplitude modulation modulator.
21. A computer program product, comprising at least one non-transitory computer readable storage medium having a computer readable program code portion stored thereon, the computer readable program code portion comprising:
program code instructions for providing a first bit sequence of continuous bits “1” or continuous bits “0”;
program code instructions for generating a second bit sequence by replacing, in each of a plurality of modulation intervals with a predetermined bit number N modulation _ interval , wherein N is an integer, at least one bit of the first bit sequence at least one fixed position of the respective modulation interval with one information bit from an information bit sequence; and
program code instructions for modulating the second bit sequence so as to generate a positioning packet with a modulated continuous wave signal for transmission.
22. A computer program product, comprising at least one non-transitory computer readable storage medium having a computer readable program code portion stored thereon, the computer readable program code portion comprising:
program code instructions for receiving a positioning packet with a modulated continuous wave signal via a plurality of different antenna elements;
program code instructions for demodulating the modulated continuous wave signal to obtain a first bit sequence including a plurality of modulation intervals with a predetermined bit number N modulation _ interval , wherein at least one information bit occupies at least one fixed position in each of said plurality of modulation intervals and continuous bits “1” or continuous bits “0” occupy the other positions in the respective modulation intervals; and
program code instructions for performing concurrently, based on the modulated continuous wave signal, positioning measurement by measuring phase differences among the plurality of different antenna elements at each of a number N measurement _ points of measurement points,
wherein N is an integer.