Method for spreading a plurality of data symbols onto subcarriers of a carrier signal
View Patent ↗A method for spreading a plurality of data symbols onto subcarriers of a carrier signal for a transmission in a transmission system provides a data vector, including the plurality of data symbols. The provided data vector is transformed, and based on the transformed data vector and a spreading matrix subsequent to the transform, a spread data vector is being created, having a length which corresponds to the number of the subcarriers.
1. A method for spreading a plurality of data symbols onto subcarriers of a carrier signal for a transmission in a transmission system, comprising:
providing a data vector, comprising the plurality of data symbols;
performing a spreading allocation of the data vector using a spreading allocation matrix to deliver a vector exhibiting a length which corresponds to the number of subcarriers,
transforming, by a transformer, the delivered vector; and
after transforming the delivered vector, spreading the transformed data vector using a spreading matrix, to thereby create a spread data vector,
wherein the spread data vector has a length which corresponds to the number of subcarriers,
wherein the spreading allocation assigns the data symbols in the data vector to the inputs of a transformer.
2. The method according to claim 1 , wherein the spreading matrix comprises a diagonal matrix.
3. The method according to claim 1 , wherein the spreading matrix comprises a diagonal matrix, which is defined by a spreading sequence.
4. The method according to claim 3 , wherein the spreading sequence comprises a sequence with perfect periodic autocorrelation function (PACF).
5. The method according to claim 4 , wherein the spreading sequence comprises one of the following sequences:
(1) a Frank sequence,
(2) a Frank-Zadoff-Chu sequence,
(3) a sequence, which results from the sequences mentioned under (1) and (2) by invariance operations,
(4) a sequence, which results from the sequences mentioned under (1)-(3) by discrete Fourier transform (DFT) or inverse discrete Fourier transform (IDFT),
(5) a sequence, which results from the sequences mentioned under (4) by invariance operations.
6. The method according to claim 3 , wherein the spreading sequence comprises a sequence with good periodic autocorrelation function (PACF).
7. The method according to claim 6 , wherein the spreading sequence comprises one of the following sequences:
(1) a binary m-sequence,
(2) a binary Legendre sequence,
(3) a binary generalized Sidelnikov sequence,
(4) a Twin-Prime sequence,
(5) a Barker sequence,
(6) a quadriphase Legendre sequence,
(7) a quadriphase generalized Sidelnikov sequence,
(8) a quadriphase complement-based sequence,
(9) a quadriphase Lee sequence,
(10) a sequence, which results from the sequences mentioned under (1)-(9) by invariance operations.
8. The method according to claim 1 , wherein the spreading allocation matrix comprises the elements 1 and 0, wherein:
∑
m
=
1
M
[
T
]
n
m
∈
{
0
,
1
}
∀
n
=
1
…
N
applies, so that any of the N parallel inputs of the base spreading module is only allocated one-fold, and
∑
n
=
1
N
[
T
]
n
m
>
0
∀
m
=
1
…
M
,
so that all M data symbols are taken into consideration for base spreading, with
M number of data symbols, and
N number of subcarriers.
9. The method according to claim 8 , wherein, for the spreading allocation matrix the following applies:
∑
n
=
1
N
[
T
]
n
m
=
1
∀
m
=
1
…
M
wherein the spreading allocation matrix is composed of a unit matrix and a zero matrix as follows:
T
block
=
(
I
M
0
(
N
-
M
)
,
M
)
,
or
wherein the spreading allocation matrix results from an auxiliary matrix as follows:
T
rake
=
(
T
h
0
(
N
-
⌊
N
M
⌋
·
M
)
,
M
)
,
with the auxiliary matrix being defined as follows:
T
h
=
I
M
⊗
(
1
0
(
⌊
N
M
⌋
-
1
)
,
1
)
with:
I unit matrix, and
0 zero matrix.
10. The method according to claim 9 , wherein the spreading allocation matrix comprises a cyclically shifted matrix.
11. The method according to claim 1 , wherein, in support of K users of the transmission system, one user-specific spreading allocation matrix respectively allocated to a user k is used, where also:
∑
k
=
1
K
∑
m
=
1
M
[
T
k
]
n
m
∈
{
0
,
1
}
∀
n
=
1
…
N
,
so that any of the N parallel inputs of the base spreading module is only allocated one-fold, in case of multiple users.
12. The method according to claim 1 , comprising:
further processing of the spread data vector by the transmission system.
13. The method according to claim 12 , wherein the carrier signal comprises an OFDM signal with N subcarriers, with M coded data symbols being spread onto the N subcarriers, and wherein the provided data vector is being transformed by an inverse discrete Fourier transform.
14. A method for de-spreading of a signal being transmitted in a transmission system, which comprises a plurality of data symbols, which were spread onto subcarriers of a carrier signal by a method according to claim 1 , comprising:
providing a receive vector of the length N, which comprises the data symbols; and
de-spreading the provided receive vector by
de-spreading the receive vector, and
applying an inverse spreading allocation matrix for selecting a symbol vector of the length M.
15. The method according to claim 14 , wherein the de-spreading comprises a multiplication with the inverse of the base spreading matrix, which is equivalent to the spreading sequence.
16. The method according to claim 15 , wherein the base spreading matrix, which is equivalent to the spreading sequence, results as follows:
C eq =circ(c eq ), with
c
eq
=
1
N
Fu
=
1
N
DFT
(
u
)
,
where F is the discrete Fourier transform (DFT) matrix, and
1
N
is a scaling factor.
17. A non-transitory computer readable medium including a computer program comprising a program code for implementing the method according to claim 1 , when the program code runs on a computer or processor.
18. A non-transitory computer readable medium including a computer program comprising a program code for implementing the method according to claim 14 , when the program code runs on a computer or processor.
19. An apparatus for spreading a plurality of data symbols onto subcarriers of a carrier signal for a transmission in a transmission system, the apparatus comprising:
a serial/parallel converter to provide a data vector comprising the plurality of data symbols;
a first spreader to perform a spreading allocation of the data vector using a spreading allocation matrix to deliver a vector exhibiting a length which corresponds to the number of subcarriers,
a transformer to transform the delivered vector; and
a second spreader to perform, after transforming the delivered vector, a spreading of the transformed data vector using a spreading matrix, to thereby create a spread data vector, wherein
the spread data vector has a length that corresponds to the number of subcarriers, and
the spreading allocation assigns the data symbols in the data vector to the inputs of the transformer.
20. An apparatus for de-spreading a signal that comprises a plurality of data symbols spread onto subcarriers of a carrier signal by an apparatus for spreading a plurality of data symbols onto subcarriers of a carrier signal for a transmission, wherein
the apparatus for spreading comprises: a serial/parallel converter to provide a data vector comprising the plurality of data symbols, a first spreader to perform a spreading allocation of the data vector using a spreading allocation matrix to deliver a vector exhibiting a length which corresponds to the number of subcarriers, a transformer to transform the delivered vector; and a second spreader to perform, after transforming the delivered vector, spreading of the transformed data vector using a spreading matrix, to thereby create a spread data vector, wherein the spread data vector has a length which corresponds to the number of subcarriers, wherein the spreading allocation assigns the data symbols in the data vector to the inputs of the transformer; and
the apparatus for de-spreading comprises: a serial/parallel converter to provide a receive vector of the length N, which comprises the data symbols, a de-spreader to de-spread the receive vector, and to apply an inverse spreading allocation matrix for selecting a symbol vector of the length M.
21. A transmission system, comprising:
a transmitter, which comprises an apparatus for spreading a plurality of data symbols onto subcarriers of a carrier signal for a transmission in the transmission system, the apparatus for spreading comprising: serial/parallel converter to provide a data vector comprising the plurality of data symbols, a first spreader to perform a spreading allocation of the data vector using a spreading allocation matrix to deliver a vector exhibiting a length which corresponds to the number of subcarriers, a transformer to transform the delivered vector; and a second spreader to perform, after transforming the delivered vector, spreading of the transformed data vector using a spreading matrix, to thereby create a spread data vector, wherein the spread data vector has a length which corresponds to the number of subcarriers, wherein the spreading allocation assigns the data symbols in the data vector to the inputs of the transformer; and
a receiver, which comprises an apparatus for de-spreading, the apparatus for de-spreading comprising: a serial/parallel converter to provide a receive vector of the length N, which comprises the data symbols, a de-spreader to de-spread the receive vector, and to apply an inverse spreading allocation matrix for selecting a symbol vector of the length M.