TWO-DIMENSIONAL PILOT PATTERNS
The present invention relates to a method for generating, in a multiple access communication system, two-dimensional pilot signal patterns for propagation channel estimation in time and frequency, with equidistant sampling. The method includes the steps of: generating a generic pilot pattern that covers completely a first dimension and covers partially a second dimension, within a segment of the second dimension where the propagation channel is considered to have a constant value, and performing periodical duplication of the generic pilot pattern along the second dimension, where the duplication interval of the generic pilot pattern is equal to the required sampling interval in the second dimension. The invention also relates to a transmitter and a receiver of a multiple access communication system, such as a multiple access communication system and a radio multiple access communication system.
1 . A method for generating, in a multiple access communication system, two-dimensional pilot signal patterns for propagation channel estimation in time and frequency, with equidistant sampling, said patterns comprising tones placed in time and frequency units, the method comprising:
generating a generic pilot pattern that covers completely a first dimension and covers partially a second dimension, within a segment of the second dimension where the propagation channel is considered to have a constant value;
performing periodical duplication of the generic pilot pattern along the second dimension, where the duplication interval of the generic pilot pattern is equal to the required sampling interval in the second dimension.
2 . The method according to claim 1 , wherein the first dimension is time and the second dimension is frequency, or vice versa.
3 . The method according to claim 1 , wherein the generic pilot pattern is obtained from an integer sequence by separating the successive sequence elements with equal number of empty signalling units, corresponding to the required sampling interval in the first dimension, while the sequence elements determine the position of tones in the second dimension.
4 . The method according to claim 3 , wherein the integer sequence is obtained by mapping from a sequence f(i)=P[x(i)], where
P
(
x
)
=
∑
j
=
0
k
n
j
x
j
is an associated polynomial of a degree k, whose argument function x(i) is a sequence of elements of a Galois Field GF(Q), where “i” is the ordinal number of the sequence element x(i), and where multiplications and additions in the polynomial P(x) are performed in GF(Q), Q is power of prime.
5 . The method according to claim 4 , wherein a set of generic pilot patterns are obtained from a set of associated polynomials with different coefficients.
6 . The method according to claim 5 , wherein Q is a prime, the argument function is x(i)=i, i=0,1,2, . . . , Q−1, the coefficient n k−1 is fixed and all other coefficients nj take all the values from GF(Q).
7 . The method according to claim 5 , wherein Q is a power of prime and the argument function is x(i)=α i , i=0,1,2, . . . , Q−2, α is a primitive element of GF(Q), the coefficient n 1 is fixed and all other coefficients n j take all the values from GF(Q).
8 . The Method according to claim 5 , wherein Q is a prime, the argument function is
x
(
i
)
=
{
1
/
i
,
i
=
1
,
2
,
…
,
Q
-
1
0
,
i
=
0
,
and all the coefficients nj take all the values from GF(Q).
9 . The Method according to claim 8 , wherein the coefficient no is fixed and all other coefficients n j take all the values from GF(Q).
10 . A transmitter in a multiple access communication system comprising a processor configured to implement a method for generating two-dimensional pilot signal patterns for propagation channel estimation in time and frequency, with equidistant sampling, said patterns comprising tones placed in time and frequency units, wherein the method comprises:
generating a generic pilot pattern that covers completely a first dimension and covers partially a second dimension, within a segment of the second dimension, wherein the propagation channel is considered to have a constant value;
performing periodical duplication of the generic pilot pattern along the second dimension, wherein the duplication interval of the generic pilot pattern is equal to the required sampling interval in the second dimension
11 . The transmitter according to claim 10 wherein the processor is arranged to pseudo-randomly change pilot patterns from one transmission interval to another.
12 . A receiver for a multiple access communication system comprising a processor configured to receive and process signals generated by a transmitter in the multiple access communication system comprising a processor configured to implement a method for generating two-dimensional pilot signal patterns for propagation channel estimation in time and frequency, with equidistant sampling, said patterns comprising tones placed in time and frequency units, the method comprising:
generating a generic pilot pattern that covers completely a first dimension and covers partially a second dimension, within a segment of the second dimension, wherein the propagation channel is considered to have a constant value;
performing periodical duplication of the generic pilot pattern along the second dimension, wherein the duplication interval of the generic pilot pattern is equal to the required sampling interval in the second dimension.
13 . The receiver according to claim 12 , wherein the processor comprised in the transmitter is arranged to pseudo-randomly change pilot patterns from one transmission interval to another.
14 . A multiple access communication system comprising:
at least one transmitter adapted to execute a method for generating two-dimensional pilot signal patterns for propagation channel estimation in time and frequency, with equidistant sampling, said patterns comprising tones placed in time and frequency units, wherein the method comprises:
generating a generic pilot pattern that covers completely a first dimension and covers partially a second dimension within a segment of the second dimension, wherein the propagation channel is considered to have a constant value;
performing periodical duplication of the generic pilot pattern along the second dimension, wherein the duplication interval of the generic pilot pattern is equal to the required sampling interval in the second dimension; and
at least one receiver adapted to receive and process signals generated by the at least one transmitter.
15 . The multiple access communication system according to claim 14 , wherein the transmitter is arranged to pseudo-randomly change pilot patterns from one transmission interval to another.
16 . A radio multiple access communication system with a number of antennas, wherein various subsets of orthogonal pilot patterns, wherein a set of generic pilot patterns obtained from a set of associated polynomials with different coefficients are allocated to different users, so that each orthogonal pattern is used for the transmission from a particular transmit antenna ( 240 ).
17 . The radio multiple access communication system according to claim 16 , wherein the pilot is changed pseudo-randomly from one transmission interval to another.