Method and apparatus for robust MIMO transmission
A method for operating a user equipment (UE) comprises receiving information about a downlink (DL) transmission transmitted from N RRH >1 RRHs, wherein: N RRH =number of remote radio heads (RRHs), RRH r comprises a group of antenna ports, and r=1, . . . , N RRH ; receiving the DL transmission; and decoding the information about the DL transmission; wherein the DL transmission is based on a scheme that is a combination of a precoding scheme and a diversity scheme, wherein the precoding scheme corresponds to applying an intra-RRH precoder component to antenna ports within an RRH, and wherein the diversity scheme corresponds to applying an inter-RRH diversity component to antenna ports across RRHs.
1. A user equipment (UE) comprising:
a transceiver configured to:
receive information about a report associated with N remote radio heads (RRHs), where N>1 and each of the N RRHs comprises a group of antenna ports, and
receive a channel state information-reference signal (CSI-RS) configuration including information about (i) one non-zero power (NZP) CSI-RS resource associated with all of the N RRHs or (ii) N NZP CSI-RS resources, each associated with one of the N RRHs; and
a processor operably coupled to the transceiver, the processor:
based on the CSI-RS configuration, configured to measure the one NZP CSI-RS resource or the N NZP CSI-RS resources, and
based on the information about the report, configured to determine n delay values, d 1 , . . . d n , where 1<n≤N,
wherein the transceiver is further configured to transmit the report including information about the n delay values, d 1 , . . . d n .
2. The UE of claim 1 , wherein each of the N NZP CSI-RS resources is associated with 1 or 2 CSI-RS ports, or density=1 or 3 REs per RB.
3. The UE of claim 1 , wherein each of the one NZP CSI-RS resource or the N NZP CSI-RS resources is an aperiodic NZP CSI-RS resource.
4. The UE of claim 1 , wherein n=1, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =(r−1)d 1 or (ρ(r)−1)d 1 , where ρ is a permutation function which permutes the RRH indices.
5. The UE of claim 1 , wherein:
n=N, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =d r , or
n=N−1, and for one of the N RRHs with index r*, a delay value is Δ r* =0, and for each of the remaining N RRHs with index r∈{1, . . . , N} and r≠r*, a delay value is given by Δ r =d r .
6. The UE of claim 1 , wherein a unit of the n delay values is in number of orthogonal frequency division multiplexing (OFDM) symbols or in length of a cyclic prefix (CP).
7. The UE of claim 1 , wherein the report is:
standalone including only the n delay values, or
multiplexed with at least one of CSI, a scheduling request (SR), or a hybrid automatic repeat request acknowledgement (HARQ-ACK).
8. A method performed by a user equipment (UE), the method comprising:
receiving information about a report associated with N remote radio heads (RRHs), where N>1 and each of the N RRHs comprises a group of antenna ports;
receiving a channel state information-reference signal (CSI-RS) configuration including information about (i) one non-zero power (NZP) CSI-RS resource associated with all of the N RRHs or (ii) N NZP CSI-RS resources, each associated with one of the N RRHs;
based on the CSI-RS configuration, measuring the one NZP CSI-RS resource or the N NZP CSI-RS resources;
based on the information about the report, determining n delay values, d 1 , . . . d n , where 1≤n≤N; and
transmitting the report including information about the n delay values, d 1 , . . . d n .
9. The method of claim 8 , wherein each of the N NZP CSI-RS resources is associated with 1 or 2 CSI-RS ports, or density=1 or 3 REs per RB.
10. The method of claim 8 , wherein each of the one NZP CSI-RS resource or the N NZP CSI-RS resources is an aperiodic NZP CSI-RS resource.
11. The method of claim 8 , wherein n=1, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =(r−1)d 1 or (ρ(r)−1)d 1 , where ρ is a permutation function which permutes the RRH indices.
12. The method of claim 8 , wherein:
n=N, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =d r , or
n=N−1, and for one of the N RRHs with index r*, a delay value is Δ r* =0, and for each of the remaining N RRHs with index r∈{1, . . . , N} and r≠r*, a delay value is given by Δ r =d r .
13. The method of claim 8 , wherein a unit of the n delay values is in number of orthogonal frequency division multiplexing (OFDM) symbols or in length of a cyclic prefix (CP).
14. A base station (BS) comprising:
a processor configured to identify information about a report associated with N remote radio heads (RRHs), where N>1 and each of the N RRHs comprises a group of antenna ports; and
a transceiver operably coupled to the processor, the transceiver configured to:
transmit the information,
transmit a channel state information-reference signal (CSI-RS) configuration including information about (i) one non-zero power (NZP) CSI-RS resource associated with all of the N RRHs or (ii) N NZP CSI-RS resources, each associated with one of the N RRHs, and
receive the report including information about n delay values, d 1 , . . . d n , where 1≤n≤N,
wherein the n delay values are associated with the one NZP CSI-RS resource or the N NZP CSI-RS resources.
15. The BS of claim 14 , wherein each of the N NZP CSI-RS resources is associated with 1 or 2 CSI-RS ports, or density=1 or 3 REs per RB.
16. The BS of claim 14 , wherein each of the one NZP CSI-RS resource or the N NZP CSI-RS resources is an aperiodic NZP CSI-RS resource.
17. The BS of claim 14 , wherein n=1, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =(r−1)d 1 or (ρ(r)−1)d 1 , where ρ is a permutation function which permutes the RRH indices.
18. The BS of claim 4 , wherein:
n=N, and for each RRH with index r∈{1, . . . , N}, a delay value is given by Δ r =d r , or
n=N−1, and for one of the N RRHs with index r*, a delay value is Δ r* =0, and for each of the remaining N RRHs with index r∈{1, . . . , N} and r≠r*, a delay value is given by Δ r =d r .
19. The BS of claim 14 , wherein a unit of the n delay values is in number of orthogonal frequency division multiplexing (OFDM) symbols or in length of a cyclic prefix (CP).