Time domain pilot of single-carrier MIMO system and synchronization method thereof
The present invention discloses a time domain pilot design solution suitable for a single-carrier MIMO system. The design solution comprises a time domain pilot location design and a training sequence design. In the present invention, several identical ZCZ sequences are uniformly inserted into each of the data blocks in the same data stream to serve as training sequences, wherein the training sequences inserted into different data streams are different. In addition, the present invention also discloses a simple algorithm for pilot tracking and phase correction suitable for the time domain pilot design solution for the single-carrier MIMO system. The time domain pilot design solution for a single-carrier MIMO system and the algorithm for pilot tracking and phase correction as disclosed in the present invention can improve the performance of a system.
1. A synchronization method based on time domain pilot of a single-carrier multi-input multi-output (MIMO) system, comprising the following steps:
(1) performing fast Fourier transformation (FFT), equalization and inverse fast Fourier transformation (IFFT) on data blocks received from different antennas, and estimating a phase error at a central symbol position of each training sequence (TS) in the data blocks;
(2) shifting the TS sequence in a cyclic prefix (CP);
(3) utilizing the TS sequence in the CP for shifting, performing FFT, equalization and IFFT transformation on the data blocks in which the TS sequence is shifted, and estimating a phase error at an initial position of data blocks; and
(4) estimating and compensating for a phase error of each data symbol in the data blocks,
wherein the method for estimating the phase error of each data symbol is as follows:
supposing N TS represents the length of the TS sequence, N D represents the number of data symbols between every two adjacent TS sequences, M represents the number of TS sequences inserted into each data block; s[i],i=1, 2, . . . , N TS represents the inserted TS sequences; {circumflex over (x)}′[i],i=1, 2, . . . , N represents a time domain signal obtained after FFT, equalization and IFFT transformation of N points is performed on the received time domain signal y[i], i=1, 2, . . . , N; r m [i],i=1, 2, . . . , N TS ,m=1, 2, . . . , M represents the i th pilot symbol of the m th TS sequence in the transformed data symbol block; and {circumflex over (x)}′[i],i=1, 2, . . . , N represents a time domain signal obtained after FFT, equalization and IFFT transformation of N points is performed on the received data symbol {y[−N TS +1], . . . , y[−1], y[0], y[1], y[2], . . . , y[i], . . . y[N−N TS +1]}, then
the phase error at the central symbol position of each TS sequence in the data block is as follows:
θ
m
=
∠
(
∑
i
=
1
N
TS
r
m
[
i
]
s
*
[
i
]
)
,
m
=
1
,
2
,
…
,
M
(
formula
12
)
the phase error at the initial position of the data block is as follows:
θ
0
=
∠
(
∑
i
=
1
N
TS
x
^
′
[
i
]
s
*
[
i
]
)
(
formula
14
)
the phase error of each data symbol {circumflex over (x)}′[i],i=1, 2, . . . , N in the data block is as follows:
θ
[
i
]
=
{
θ
1
-
θ
0
N
D
+
N
TS
(
i
-
N
D
-
⌈
N
TS
+
1
2
⌉
)
+
θ
1
,
if
1
≤
i
<
N
D
+
⌈
N
TS
+
1
2
⌉
θ
m
-
θ
m
-
1
N
D
+
N
TS
(
i
-
mN
D
-
(
m
-
1
)
N
TS
-
⌈
N
TS
+
1
2
⌉
)
+
θ
m
,
if
a
≤
i
<
b
wherein
a
=
(
m
-
1
)
N
D
+
(
m
-
2
)
N
TS
+
⌈
N
TS
+
1
2
⌉
,
b
=
mN
D
+
(
m
-
1
)
N
TS
+
⌈
N
TS
+
1
2
⌉
.
(
formula
15
)
2. The synchronization method based on time domain pilot of a single-carrier MIMO system of claim 1 , wherein the method of phase error compensation is as follows:
{circumflex over ({circumflex over (x)})} [ i ]= {circumflex over (x)} [ i ]□ e −jθ[i] , i= 1,2, . . . , N (formula 16),
wherein {circumflex over (x)}′[i],i=1, 2, . . . , N represents a time domain signal obtained after FFT where the N represents a number of samples, equalization and IFFT transformation of N points is performed on the received data symbol y[i], i=1, 2, . . . , N; and θ i =1, 2, . . . , N represents a phase error of each data symbol in the data blocks.