Sequence initialization for demodulation reference signal
View Patent ↗A new sequence initialization for demodulation reference signal (DMRS) sequence design used in the LTE-A system is provided. In some implementations, the modulo-2 addition of n SCID and n NDI , both of which are provided in a downlink control information (DCI) message, is used to dynamically select one of a plurality of parameter candidates and the dynamically selected parameter is then used for determining the initialization state of a DMRS sequence. In some other implementations, the modulo-2 addition of n SCID and n NDI is used for determining the least significant bit of the initialization state of the DMRS sequence.
1. A method of dynamically selecting one parameter X from multiple candidates {x(0), x(1), . . . x(N-1)} to initialize a linear feedback shift register for generating a downlink demodulation reference signal (DMRS) sequence, wherein the linear feedback shift register has an initialization state that is a function of X and n SCID , wherein the method is performed by a system having one or more processors and:
the parameter X is dynamically selected from multiple candidate values based on an NDI bit in a DCI message, n SCID information provided by the DCI message, or a combination of the NDI bit and the n SCID information provided by DCI message; and
specific values are assigned to the multiple candidates {x(0), x(1), . . . x(N-1)}.
2. The method recited in claim 1 , wherein X=x(n NDI ) for N=2 and
n
NDI
=
{
NDI
bit
for
codeword
1
in
DCI
-
2
C
one
codeword
0
two
codewords
3. The method recited in claim 1 , wherein X=x(2·n NDI +n SCID ) or
X
=
x
(
2
·
n
SCID
+
n
NDI
)
for
N
=
4
,
and
n
NDI
=
{
NDI
bit
for
codeword
1
in
DCI
-
2
C
one
codeword
0
two
codewords
n
SCID
=
{
n
SCID
bit
in
DCI
format
2
C
M
codeword
and
M
layer
,
M
=
{
1
,
2
}
0
otherwise
4. The method recited in claim 3 , wherein one specific x(n) candidate, whose index n corresponds to n NDI =0 and n SCID =1 such that it is represented equivalently by x(n NDI =0,n SCID =1), is assigned with a unique value on a TP-basis in the neighboring area such that different TPs in the neighboring area have different x(n NDI =0,n SCID =1); and x(n NDI =0,n SCID =1) is not equal to x(n NDI =0,n SCID =0) for the same TP.
5. The method recited in claim 1 , wherein
X
=
x
(
n
SCID
)
for
N
=
2
and
n
SCID
=
{
n
SCID
bit
in
DCI
message
M
codeword
and
M
layer
,
M
=
{
1
,
2
}
0
otherwise
,
and
n SCID in the equation c init =(└n s /2┘+1)·(2X+1)·2 16 +n SCID is set to zero.
6. The method recited in claim 1 , wherein one specific x(n) candidate, x(n 0 ), where n 0 is derived from the parameters allowing PDSCH transmission of up to eight layers or more than two layers, is assigned with a unique value on a TP-basis in the neighboring area, that is, different TPs in the neighboring area have different x(n 0 ).
7. The method recited in claim 6 , wherein n 0 corresponds to n NDI =0.
8. The method recited in claim 6 , wherein n 0 corresponds to n NDI =0 and n SCID =0.
9. The method recited in claim 6 , wherein n 0 corresponds to n SCID =0.
10. The method recited in claim 6 , wherein the unique value is physical cell identification (N ID cell ) of the transmission TP if the transmission TP is the macro eNB or the RRH in CoMP scenario-3.
11. The method recited in claim 6 , wherein the unique value is some number other than physical cell identification (N ID cell ) of the transmission TP if the transmission TP is the RRH in CoMP scenario-4.
12. The method recited in claim 1 , wherein one specific x(n) candidate, x(n 1 ), where n 1 ≠n 0 (n 0 is given by claim 6 ) and n 1 is derived from the parameters that do not prevent n SCID in c init from being 0, is assigned with physical cell identification (N ID cell ) of the macro TP, if the transmission TP is the RRH and can transmit to UE in cooperation with macro TP.
13. The method recited in claim 12 , wherein n 1 corresponds to n NDI =1.
14. The method recited in claim 12 , wherein n 1 corresponds to n NDI =1 and n SCID =0.
15. The method recited in claim 12 , wherein n 1 corresponds to n SCID =1.
16. The method recited in claim 1 , wherein the value range of each x(n) is between 0 and 1637 inclusively.
17. The method recited in claim 1 , wherein the initialization state that is a function of X and n SCID is given by
c init =(└ n s /2┘+1)·(2 X +1)·2 16 +[( n SCID +n UE )mod 2]; and
n UE ε{0,1} is either the UE-specific parameter configured by RRC signaling, or equal to NDI bit derived from DCI message.
18. The method recited in claim 1 , wherein the initialization state that is a function of X and n SCID is given by c init =(└n s /2┘+1)·(2X+1)·2 16 +n SCID .
19. The method recited in claim 1 , wherein the system is a base station.
20. The method recited in claim 1 , wherein the system is a user equipment.