Method, transceiver and telecommunication system for generating reference sequence matrices and for mapping elements thereof
An method for, in a cellular telecommunication system, generating reference sequence matrices and for mapping elements of said reference sequence matrices to reference signal positions having predetermined locations in two-dimensional multi-carrier time-frequency symbol spaces is provided. According to the method, a matrix S N of dimension N×N having N orthogonal rows or columns and orthogonal parts of rows or columns, respectively, N being a positive integer >3, is generated. N reference sequence matrices OS (k) , k=0, . . . , N−1, are then generated by forming rows or columns of the kth reference sequence matrix OS (k) based on at least part of the (k+1)th row or column, respectively, of said orthogonal matrix S N . Further, in a cell, within a given time period, mapping elements of one of said N reference sequence matrices OS (k) to reference signal positions having predetermined locations in two-dimensional multi-carrier time-frequency symbol spaces.
1. A method for generating a reference sequence matrix and mapping elements of the reference sequence matrix to a position of a reference signal used for channel estimation in a cellular telecommunication system, the method comprising:
generating, by a transceiver, a matrix S N of dimension N×N having N orthogonal rows or columns, with N being a positive integer >3;
generating, by the transceiver, a plurality of reference sequence matrices OS (k) , k=0, . . . , N−1, from the matrix S N ; and
mapping, by the transceiver, elements of at least one of the reference sequence matrices to a position of a reference signal having predetermined locations in a two-dimensional time-frequency symbol space, wherein rows or columns of a kth reference sequence matrix OS (k) are based at least in part on a (k+1)th row or column of the matrix S N .
2. The method according to claim 1 , wherein the mapping comprises:
mapping in a cell, within a given time period, elements of at least one of the reference sequence matrices by assigning elements located in vicinity of each other in a mapped reference sequence matrix to locations in vicinity of each other in the two-dimensional time-frequency symbol space.
3. The method according to claim 1 , wherein the matrix S N is generated according to:
S
N
=
A
⊗
B
=
(
a
11
B
…
a
1
M
B
⋮
⋱
⋮
a
M
1
B
…
a
MM
B
)
,
wherein A is an orthogonal matrix of dimension M×M, B is an orthogonal matrix of dimension L×L, and denotes a Kronecker product.
4. The method according to claim 3 , wherein the matrix S N is generated from a recursion
S
2
L
·
l
=
(
S
L
·
l
S
L
·
l
S
L
·
l
-
S
L
·
l
)
,
l
=
1
,
2
,
4
…
,
2
m
-
1
,
where S L =B, N=ML, M=2 m , and m is an integer greater than 0.
5. The method according to claim 4 , wherein said matrix B is:
B
=
(
1
1
1
1
ⅇ
j
2
π
/
3
ⅇ
j
4
π
/
3
1
ⅇ
j
4
π
/
3
ⅇ
j
2
π
/
3
)
·
ⅇ
j
ϕ
,
where 0≦φ<2π.
6. The method according to claim 4 , wherein said matrix B is:
B
=
(
1
1
1
-
1
)
·
ⅇ
j
ϕ
,
where 0≦φ<2π.
7. The method according to claim 1 , wherein the mapping further comprises: mapping, for each of a number of cells controlled by a Node B in the cellular telecommunication system, elements of at least one of the reference sequence matrices on the two-dimensional time-frequency symbol space for each cell.
8. The method according to claim 1 , wherein the mapping further comprises: mapping elements of at least one of the reference sequence matrices on the two-dimensional time-frequency symbol space of at least two cells controlled by a Node B in the cellular telecommunication system.
9. The method according to claim 1 , wherein the reference sequence matrices are arranged in subsets, and reference sequence matrices within each subset are orthogonal.
10. The method according to claim 1 , wherein the reference sequence matrices are arranged in subsets, and each subset is associated with a cell specific information, and each subset implicitly encodes the associated cell specific information when each subset is chosen to be used in a cell of the cellular telecommunication system.
11. The method according to claim 10 , wherein the associated cell specific information relating to an antenna configuration is used in the cell of the cellular telecommunication system.
12. The method according to claim 1 , wherein the two-dimensional time-frequency symbol space is organized in a lattice structure defined as:
x=m 1 a 1 +m 2 a 2 ,
where m 1 and m 2 are integers, and a 1 and a 2 are independent elements of a time-frequency grid.
13. The method according to claim 1 , wherein the kth reference sequence matrix OS (k) is generated using at least one cyclic shift of the (k+1)th row or column of the matrix S N , or at least one cyclic shift on segments of the (k+1)th row or column of the matrix S N .
14. The method according to claim 13 , wherein the reference sequence matrices are arranged in subsets defined by:
Ω k ={OS 3(k-1) ,OS 1+3(k-1) ,OS 2+3(k-1) }, k= 1, 2, 3, 4,
each subset Ω k being associated with information relating to an antenna configuration.
15. The method according to claim 1 , wherein the kth reference sequence matrix OS (k) is generated by repeating the (k+1)th row or column of the matrix S N .
16. The method according to claim 1 , wherein the mapping comprises assigning elements of concatenations of the reference sequence matrices
(
O
S
(
k
)
…
O
S
(
k
)
⋮
⋱
⋮
O
S
(
k
)
…
O
S
(
k
)
)
.
17. The method according to claim 1 , wherein more than one row or more than one column of a reference sequence matrix from the plurality of reference sequence matrices is generated by dividing one single row or one single column, respectively, in the matrix S N into parts, and assigning the divided parts to more than one row or more than one column in the reference sequence matrix.
18. The method according to claim 1 , wherein the reference sequence matrices are used for identifying at least part of the cell ID in a cell search procedure.
19. The method according to claim 1 , wherein the matrix S N is of dimension N 1 ×N 2 having N 1 orthogonal rows or N 2 orthogonal columns, N 1 and N 2 are positive integers, min(N 1 ,N 2 )>3, and the reference sequence matrices OS (k) , k=0, . . . , min(N 1 ,N 2 )−1, are generated from the matrix S N .
20. The method according to claim 1 , further comprising: constructing a reference symbol sequence as a product of a pseudo-random sequence and one of the reference sequence matrices OS (k) .
21. The method according to claim 1 , wherein the mapping is performed by mapping a matrix description onto resource elements used for the reference signal.
22. The method according to claim 1 , wherein reference sequence matrices from the plurality of reference sequence matrices are orthogonal to each other.
23. A transceiver for use in a cellular telecommunication system, said transceiver being arranged for generating a reference sequence matrix and mapping elements of the reference sequence matrix to a position of a reference signal used for channel estimation in the cellular telecommunication system, the transceiver configured to:
generate a matrix S N of dimension N×N having N orthogonal rows or columns, with N being a positive integer >3;
generate a plurality of reference sequence matrices OS (k) , k=0, . . . , N−1, from the matrix S N ; and
map elements of at least one of the reference sequence matrices to a position of a reference signal having predetermined locations in a two-dimensional time-frequency symbol space, wherein rows or columns of a kth reference sequence matrix OS (k) are based at least in part on a (k+1)th row or column respectively, of the matrix S N .
24. The cellular telecommunication system of claim 23 , the system comprising at least one transceiver.