Methods and systems for CSI-RS resource allocation in LTE-advance systems
Systems and methods for the configuration of channel state information reference signals (CSI-RS) are disclosed. The systems and methods include providing user equipment with the locations of CSI-RS reuse information. Several encoding patterns and exemplary methodology for both the identification of the CSI-RS resource element locations are provided in exemplary embodiments. In addition, exemplary embodiments provide muting methods and systems for a physical downlink shared channel resource elements.
1. A method for transmitting a channel state information reference signal (CSI-RS) comprising:
identifying a location of one or more subframes where one or more CSI-RS reuse patterns are transmitted;
identifying a location of one or more resource elements (REs) used to transmit a CSI-RS within a CSI-RS subframe wherein the REs that comprise a CSI-RS reuse pattern are specified by the number of CSI-RS ports and the location of a first resource element (RE # 0 ) in the reuse pattern;
providing a location of the one or more subframes and one or more REs where the one or more CSI-RS reuse patterns are transmitted to one or more pieces of user equipment (UE); and
generating one or more CSI-RS modulation symbols in one or more CSI-RS REs, respectively, where each symbol contains a CSI-RS sequence element as a multiplication component.
2. The method of claim 1 wherein the subframe instances that transmit the CSI-RS are specified by a frame index n ƒ and a slot index n s (0≦n s <20) that satisfies (10×n ƒ +└n s /2┘−Δ CSIRS )mod T CSIRS =0, where T CSIRS and Δ CSIRS are respectively the subframe period and the subframe offset of the CSI-RS, and are signaled to the UE by a high-layer radio resource control (RRC) parameter I CSIRS , based upon a predefined table, where I CSIRS is the CSI-RS configuration index.
3. The method of claim 1 wherein a number of CSI-RS ports and the location of RE # 0 in the CSI-RS reuse pattern are separately encoded.
4. The method of claim 3 wherein the number of CSI-RS ports (N ANT ) is encoded in 2 bits, wherein the 2 bit binary pattern=01 for N ANT =2, 10 for N ANT =4, and 11 for N ANT =8.
5. The method of claim 3 wherein the location of RE# 0 is encoded in ┌log 2 (4×N 8Tx )┐ bits based on a table of 4*N 8Tx entries that include all locations of CSI-RS REs whose RE indices are even numbers across all CSI-RS reuse patterns of eight CSI-RS antenna ports, where N 8Tx is equal to the number of all CSI-RS reuse patterns for eight CSI-RS antenna ports.
6. The method of claim 3 wherein:
the location of the RE#0 of the m−Tx(m=the number of CSI-RS antenna ports) CSI-RS reuse pattern is equal to the location of a second resource element RE#z of a nested CSI-RS reuse pattern of eight CSI-RS antenna ports for z=m ·ƒ(x,m), where ƒ(x,m)ε{0,1,2,3} is a pre-defined function and the parameter x can be either the cell identification parameter or another RRC-signaled parameter; and
┌log 2 N 8Tx ┐, bits are used to encode the RE# 0 location of the nested CSI-RS reuse pattern based on a pre-defined table with N 8Tx entries, where N STx is equal to the number of all CSI-RS reuse patterns for eight CSI-RS antenna ports.
7. The method of claim 6 wherein x is an RRC-signaled parameter and ƒ(x,m)=xε{0,1,2,3} requires 2 more signaling bits for x.
8. The method of claim 1 , wherein
the location of the RE#0 of the m−Tx (m=the number of CSI-RS antenna ports) CSI-RS reuse pattern is equal to the location of RE#z of a nested CSI-RS reuse pattern of eight CSI-RS antenna ports, where z and m are jointly encoded; and
┌log 2 N 8Tx ┐ bits are used to encode the RE# 0 location of the nested reuse pattern based on a pre-defined table with N 8Tx entries, where N 8Tx is equal to the number of all CSI-RS reuse patterns for eight CSI-RS antenna ports.
9. The method of claim 5 , 6 , 7 , or 8 , wherein
N
8
Tx
=
{
8
normal
Cyclic
prefix
7
extended
Cyclic
prefix
10. The method of claim 1 , wherein
the relation between the index (m′) of CSI-RS sequence element (r l,n s (m′)) and the frequency-domain index (m) of physical resource block containing the CSI-RS RE to which the CSI-RS sequence element is mapped is given by
m
′
=
m
+
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
where N RB DL is the actual system bandwidth in number of physical resource block and N RB max,DL is the maximum supported bandwidth in number of physical resource block, and wherein the transmitted segment of CSI-RS sequence r l,n s (m′) is determined by sequence element index
m
′
=
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
,
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
+
1
,
…
,
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
+
N
RB
DL
-
1.
11. A system configured to receive a channel state information reference signal (CSI-RS), the system comprising:
one or more subframes within a physical resource block (PRB), wherein the subframes comprise one or more CSI-RS reuse patterns;
one or more resource elements (REs) used to transmit CSI-RS within the CSI-RS subframe wherein the REs that comprise the CSI-RS reuse patterns are specified by the number of CSI-RS ports and the location of a first resource element (RE # 0 ) in the reuse pattern;
user equipment (UE), wherein the UE comprises location information relating to the one or more subframes and the one or more REs; and
one or more CSI-RS modulation symbols configured for transmission over one or more REs within one or more subframes, where each CSI-RS symbol contains a CSI-RS sequence element as a multiplication component.
12. The system of claim 11 wherein the subframe instances that transmit the CSI-RS are specified by a frame index n ƒ and a slot index n s that satisfy (10×n ƒ +└n s /2┘−Δ CSIRS )mod T CSIRS =0, where T CSIRS and Δ CSIRS are respectively the subframe period and the subframe offset of the CSI-RS, and are signaled to the UE by a high-layer radio resource control (RRC) parameter I CSIRS , based upon a predefined table, where I CSIRS is the CSI-RS configuration index.
13. The system of claim 11 wherein a number of CSI-RS ports and the location of RE # 0 in the CSI-RS reuse pattern are separately encoded.
14. The system of claim 13 wherein the number of CSI-RS ports (N ANT ) is encoded in 2 bits, wherein the 2 bit binary pattern=01 for N ANT =2, 10 for N ANT =4, and 11 for N ANT =8.
15. The system of claim 13 wherein the location of RE# 0 is encoded in ┌log 2 (4×N 8Tx ┐ bits based on a table of 4*N 8Tx entries that include all locations of CSI-RS REs whose RE indices are even numbers across all CSI-RS reuse patterns of eight CSI-RS antenna ports, where N 8Tx equals to the number of all CSI-RS reuse patterns for eight CSI-RS antenna ports.
16. The system of claim 15 wherein
N
8
Tx
=
{
8
normal
7
extended
Cyclic
prefix
17. The system of claim 11 , wherein the relation between the index (m′) of CSI-RS sequence element (r l,n s (m′)) and the frequency-domain index (m) of a physical resource block containing the CSI-RS RE to which the CSI-RS sequence element is mapped is given by
m
′
=
m
+
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
where N RB DL is the actual system bandwidth in number of physical resource block and N RB max,DL is the maximum supported bandwidth in number of physical resource block; equivalently, the transmitted segment of CSI-RS sequence r l,n s (m′) is determined by sequence element index
m
′
=
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
,
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
+
1
,
…
,
⌊
N
RB
max
,
DL
-
N
RB
DL
2
⌋
+
N
RB
DL
-
1.