Method for generating an OFDM data signal

1. A method for generating an OFDM data signal in an OFDM signal generator, comprising:

forming a frequency domain data signal including determining a plurality of non-data carriers and setting the non-data carriers to zero in a frequency domain data signal generator;

forming a time domain data signal by performing an inverse Fourier transformation of the frequency domain data signal in a time domain data signal generator;

forming a tail section signal comprising a tail section of the time domain data signal in a tail section signal generator;

forming a multiplied tail section signal in a multiplied tail section signal generator, by forming a plurality of partial signals, each one of the partial signals being derived from the tail section signal;

forming a difference between or a sum of the multiplied tail section signal and the time domain data signal in a difference forming circuit, thereby generating the OFDM data signal with a guard interval associated therewith; and

transmitting the OFDM data signal using a transmitter circuit.

2. The method according to claim 1 , wherein forming a difference between the multiplied tail section signal and the time domain data signal comprises subtracting the multiplied tail section signal from the time domain data signal or subtracting the time domain data signal from the multiplied tail section signal.

3. The method according to claim 1 , wherein forming a difference between the multiplied tail section signal and the time domain data signal comprises forming a negated multiplied tail section signal by changing a sign of the multiplied tail section signal and superposing the time domain data signal and the negated multiplied tail section signal.

4. The method according to claim 1 , further comprising:

determining the plurality of non-data carriers in such a way that the carrier spacings satisfy the relationship

S r =( k r −k r-1 )≦ N/L , wherein

k r , N, L are the positions of the carriers in the OFDM spectrum, the total frequency band width of the OFDM spectrum, and the length of the tail section, respectively.

5. The method according to claim 1 , further comprising:

determining the plurality of non-data carriers in such a way that the carriers are equally spaced at least across a region of the OFDM spectrum.

6. The method according to claim 1 , further comprising:

forming the time domain data signal y d by inverse Fourier transformation comprises performing the following calculations:

y

n

=

1

N

⁢

∑

k

=

0

N

-

1

⁢

w

kn

*

⁢

x

k

,

wherein

w

kn

*

=

ⅇ

j

⁢

2

⁢

π

N

⁢

kn

,

wherein

N, k, n being the number of sampling points in the frequency domain, the frequency index and the time index, respectively, and wherein w* comprises a rotation factor.

7. The method according to claim 1 , further comprising:

forming the tail section signal by taking the time domain data signal and setting therein all signal components in sections outside of the tail section to zero.

8. The method according to claim 7 , further comprising:

forming the tail section signal y dg by selecting a tail section of the time domain data signal y d

y dg =Y dg ( Y d ,n g ), wherein

n g =[ N −L . . . N− 1] T and wherein

the signal components of the time domain data signal y d at 0≦n N−L−1 are set to zero, wherein

n, n g , N, L are the set of indices of non-GI samples, of GI samples, the number of sampling points in the time domain, and the number of sampling points in the tail section, respectively.

9. The method according to claim 1 , wherein forming the multiplied tail section signal comprises forming each one of the partial signals by taking a copy of the tail section, shifting the copy to a time position outside of the position of the tail section, and multiplying the copy with a rotation factor.

10. The method according to claim 9 , further comprising:

forming the multiplied tail section signal by

y

~

dg

=

∑

s

=

0

S

-

1

⁢

y

dgs

,

wherein

Y dgs =Y dgs ( w* sM,m 0 y dg ,SM+n g ), wherein the rotation factor w* sM,m 0

w

sM

,

m

0

*

=

ⅇ

j

⁢

2

·

π

N

·

(

sM

·

m

0

)

,

wherein

M, s are the time spacing between the partial signals and the index of the partial signals, respectively.

11. The method according to claim 1 , further comprising:

after forming a difference or a sum between the multiplied tail section signal and the time domain data signal, filling the tail section with a unique word.

12. The method according to claim 1 , further comprising:

performing a Fourier transform of an inverted multiplied tail section signal;

blanking a guard band from the Fourier transformed inverted multiplied tail section signal; and

performing an inverse Fourier transform of the guard blanked Fourier transformed inverted multiplied tail section signal.

13. The method according to claim 1 , further comprising:

after forming a difference or a sum between the multiplied tail section signal and the time domain data signal, blanking residual signal samples inside the tail section.

14. A method for generating an OFDM data signal in an OFDM signal generator, comprising:

generating a time domain data signal in a time domain data signal generator;

generating a tail section signal comprising a tail section of the time domain data signal in a tail section signal generator;

generating the OFDM data signal, the OFDM data signal comprising a data section and a guard interval;

generating the data section and the guard interval by forming a difference or a sum between the time domain data signal and a plurality of partial signals in an adder circuit, wherein each one of the partial signals is derived from the tail section data signal; and

transmitting the OFDM data signal using a transmitter circuit.

15. An OFDM signal generator, comprising:

a frequency domain data signal generator configured to generate a frequency domain data signal by determining a plurality of non-data carriers and setting the non-data carriers to zero;

a time domain data signal generator configured to generate a time domain data signal by performing an inverse Fourier transformation of the frequency domain data signal;

a tail section signal generator configured to generate a tail section signal comprising a tail section of the time domain data signal;

a multiplied tail section signal generator configured to form a multiplied tail section signal comprising a plurality of partial signals, wherein each one of the partial signals is based on the tail section signal;

a circuit element configured to form a difference between or a sum of the time domain data signal and the multiplied tail section signal, thereby generating an OFDM signal with a guard interval associated therewith; and

a transmitter circuit configured to transmit the OFDM signal.

16. The OFDM signal generator according to claim 15 , wherein the circuit element is configured to form the difference between the multiplied tail section signal and the time domain data signal by subtracting the multiplied tail section signal from the time domain data signal.

17. The OFDM signal generator according to claim 15 , wherein the circuit element is configured to form the difference between the multiplied tail section signal and the time domain data signal by forming a negated multiplied tail section signal by changing the sign of the multiplied tail section signal and superposing the time domain data signal and the negated multiplied tail section signal.

18. The OFDM signal generator according to claim 15 , wherein the frequency domain data signal generator is configured to determine the plurality of non-data carriers in such a way that the carrier spacings between the plurality of non-data carriers satisfy the relationship

S r =( k r −k r-1 )≦ N/L , wherein

S r , k r , N, and L are the carrier spacing, the positions of the carriers in the OFDM spectrum, the total frequency band width of the OFDM spectrum, and the length of the tail section respectively.

19. The OFDM signal generator according to claim 15 , wherein the frequency domain data signal generator is configured to determine the plurality of non-data carriers in such a way that the carriers are equally spaced in frequency at least across a region of the OFDM spectrum.

20. The OFDM signal generator according to claim 15 , wherein the time domain data signal generator is configured to form the time domain data signal y d by inverse Fourier transformation performing the following calculations:

y

n

=

1

N

⁢

∑

k

=

0

N

-

1

⁢

w

kn

*

⁢

x

k

,

wherein

w

kn

*

=

ⅇ

j

⁢

2

⁢

π

N

⁢

kn

,

wherein

N, k, n being the number of sampling points in the frequency domain, the frequency index and the time index, respectively, and x K represents a data symbol.

21. The OFDM signal generator according to claim 15 , wherein the tail section signal generator is configured to form the tail section signal by taking the time domain signal and setting therein all signal components in sections outside of the tail section to zero.

22. The OFDM signal generator according to claim 21 , wherein the tail section signal generator is configured to form the tail section signal y dg by selecting a tail section of the time domain data signal y d

y dg =y dg ( y d ,n g ), wherein

n g =[N−L . . . N− 1] T and wherein

the signal components of the time domain data signal y d at 0≦n≦N−L−1 are set to zero, wherein

n, n g , N, and L are a set of indices of non-GI samples, of GI samples, the number of sampling points in the time domain, and the number of sampling points in the tail section, respectively.

23. The OFDM signal generator according to claim 15 , wherein the multiplied tail section signal generator is configured to form the multiplied tail section signal by forming each one of the partial signals by taking a copy of the tail section, shifting the copy to a time position outside of the position of the tail section, and multiplying the copy with a rotation factor.

24. The OFDM signal generator according to claim 23 , wherein the multiplied tail section signal generator is configured to form the multiplied tail section signal by

y

~

dg

=

∑

s

=

0

S

-

1

⁢

y

dgs

,

wherein

Y dgs =Y dgs ( w* sM,m 0 y dg ,SM+n g ), wherein the rotation factor w* sM,m 0

w

sM

,

m

0

*

=

ⅇ

j

⁢

2

·

π

N

·

(

sM

·

m

0

)

,

wherein

M, s, m 0 are the time spacing between the partial signals, the index of the partial signals, and the sampling offset, respectively.

25. The OFDM signal generator according to claim 15 , further comprising:

a unique word register configured to fill the tail section of the time domain signal with a unique word after forming a difference or a sum between the multiplied tail section signal and the time domain data signal.

26. The OFDM signal generator according to claim 15 , further comprising:

a guard band blanking unit comprising a Fourier transformer, a guard band blanker, and an inverse Fourier transformer, wherein:

the Fourier transformer is configured to perform a Fourier transform of an inverted version of the multiplied tail section signal,

the guard band blanker unit is configured to blank a guard band from the Fourier transformed inverted multiplied tail section signal, and

the inverse Fourier transformer is configured to perform an inverse Fourier transform of the guard blanked Fourier transformed inverted multiplied tail section signal.

27. The OFDM signal generator according to claim 15 , further comprising:

a guard interval blanking unit configured to blank residual signal samples in the tail section signal after forming a difference or a sum between the multiplied tail section signal and the time domain data signal.

28. An OFDM signal generator, comprising:

a time domain data signal generator configured to generate a time domain data signal;

a tail section signal generator configured to generate a tail section signal comprising a tail section of the time domain data signal;

a partial signal generator configured to generate a plurality of partial signals based on the tail section signal;

a circuit element configured to form a difference between or a sum of the time domain data signal and the plurality of partial signals, thereby generating an OFDM signal with a guard interval associated therewith; and

a transmitter circuit configured to transmit the OFDM signal.