Method and apparatus for modular massive MIMO
A method for operating a user equipment (UE) comprises receiving configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N RRH >1; selecting a subset of RRHs from the N RRH RRHs independently for each subband (SB); determining the CSI report including an indicator indicating the selected subset of RRHs for each SB; and transmitting the CSI report including the indicator indicating the selected subset of RRHs for each SB.
1. A user equipment (UE) comprising:
a transceiver configured to receive configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N RRH >1; and
a processor operably coupled to the transceiver, the processor configured, based on the configuration information, to:
select a subset of RRHs from the N RRH RRHs independently for each subband (SB), and
determine the CSI report including an indicator indicating the selected subset of RRHs for each SB;
wherein the transceiver is further configured to transmit the CSI report including the indicator indicating the selected subset of RRHs for each SB.
2. The UE of claim 1 , wherein the indicator is determined based on RRH selection of |S RRH (k)| out of N RRH RRHs, for each SB k, and the CSI report is determined for the selected |S RRH (k)| RRHs for each SB k.
3. The UE of claim 2 , wherein:
the indicator is of length N RRH bits for each SB k, or
the indicator is of length
⌈
log
2
(
N
RRH
❘
"\[LeftBracketingBar]"
S
RRH
(
k
)
❘
"\[RightBracketingBar]"
)
⌉
bits for each SB k, where ┌ ┐ is a ceiling function.
4. The UE of claim 1 , wherein the indicator indicates an SB selection of |S SB (g)| out of K SBs for each RRH g, and the CSI report is determined for the selected |S SB (g)| SBs for each RRH g.
5. The UE of claim 4 , wherein:
the indicator is of length K bits for each RRH g, or
the indicator is of length
⌈
log
2
(
K
❘
"\[LeftBracketingBar]"
S
SB
(
g
)
❘
"\[RightBracketingBar]"
)
⌉
bits for each RRH g, where ┌ ┐ is a ceiling function.
6. The UE of claim 1 , wherein:
the indicator is a two-stage indicator,
a first-stage indicator indicates a set of selected RRHs S WB in a wideband (WB) manner, for all SBs, and
a second-stage indicator indicates selected |S SB (g)| SBs for each RRH g ∈ S WB .
7. The UE of claim 1 , wherein:
the indicator is a two-stage indicator,
a first-stage indicator indicates a set of selected RRHs S WB in a wideband (WB) manner, for all SBs, and
a second-stage indicator indicates selected RRHs S RRH (k) ⊂ SWB for each SB k.
8. The UE of claim 1 , wherein:
the CSI report includes a precoding matrix indicator (PMI) indicating spatial domain (SD) basis vectors, frequency domain (FD) basis vectors, and coefficients for (SD,FD) basis vector pairs, for a selected subset of SBs S SB (g) for a selected RRH g, and
for SB k when |S RRH (k)|>1, the CSI report further includes inter-RRH amplitude and phase components.
9. A base station (BS) comprising:
a processor configured to generate configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N RRH >1; and
a transceiver operably coupled to the processor, the transceiver configured to:
transmit the configuration information; and
receive the CSI report including an indicator indicating a selected subset of RRHs for each subband (SB);
wherein the subset of RRHs is selected from the N RRH RRHs independently for each subband (SB).
10. The BS of claim 9 , wherein the indicator is based on RRH selection of |S RRH (k)| out of N RRH RRHs, for each SB k, and the CSI report is based on the selected |S RRH (k)| RRHs for each SB k.
11. The BS of claim 10 , wherein:
the indicator is of length N RRH bits for each SB k, or
the indicator is of length
⌈
log
2
(
N
RRH
❘
"\[LeftBracketingBar]"
S
RRH
(
k
)
❘
"\[RightBracketingBar]"
)
⌉
bits for each SB k, where ┌ ┐ is a ceiling function.
12. The BS of claim 9 , wherein the indicator indicates an SB selection of |S SB (g)| out of K SBs for each RRH g, and the CSI report is based on the selected |S SB (g)| SBs for each RRH g.
13. The BS of claim 12 , wherein:
the indicator is of length K bits for each RRH g, or
the indicator is of length
⌈
log
2
(
K
❘
"\[LeftBracketingBar]"
S
SB
(
g
)
❘
"\[RightBracketingBar]"
)
⌉
bits for each RRH g, where ┌ ┐ is a ceiling function.
14. The BS of claim 9 , wherein:
the indicator is a two-stage indicator,
a first-stage indicator indicates a set of selected RRHs S WB in a wideband (WB) manner, for all SBs, and
a second-stage indicator indicates selected |S SB (g)| SBs for each RRH g ∈ S WB .
15. The BS of claim 9 , wherein:
the indicator is a two-stage indicator,
a first-stage indicator indicates a set of selected RRHs S WB in a wideband (WB) manner, for all SBs, and
a second-stage indicator indicates selected RRHs S RRH (k)⊂S WB for each SB k.
16. The BS of claim 9 , wherein:
the CSI report includes a precoding matrix indicator (PMI) indicating spatial domain (SD) basis vectors, frequency domain (FD) basis vectors, and coefficients for (SD,FD) basis vector pairs, for a selected subset of SBs S SB (g) for a selected RRH g, and
for SB k when |S RRH (k)|>1, the CSI report further includes inter-RRH amplitude and phase components.
17. A method for operating a user equipment (UE), the method comprising:
receiving configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N RRH >1;
selecting a subset of RRHs from the N RRH RRHs independently for each subband (SB);
determining the CSI report including an indicator indicating the selected subset of RRHs for each SB; and
transmitting the CSI report including the indicator indicating the selected subset of RRHs for each SB.
18. The method of claim 17 , further comprising:
determining the indicator based on RRH selection of |S RRH (k)| out of N RRH RRHs, for each SB k; and
determining the CSI report for the selected |S RRH (k)| RRHs for each SB k.
19. The method of claim 18 , wherein:
the indicator is of length N RRH bits for each SB k, or
the indicator is of length
⌈
log
2
(
N
RRH
❘
"\[LeftBracketingBar]"
S
RRH
(
k
)
❘
"\[RightBracketingBar]"
)
⌉
bits for each SB k, where ┌ ┐ is a ceiling function.
20. The method of claim 17 , wherein the indicator indicates an SB selection of |S SB (g)| out of K SBs for each RRH g, and
the method further comprises determining the CSI report for the selected |S SB (g)|SBs for each RRH g.