Data transmission method and apparatus
View Patent ↗The present disclosure provides a data transmission method. A UE receives CSI-RS configuration signaling from a base station, measuring and reporting CSI according to the CSI-RS configuration signaling. The UE receives scheduling signaling from the base station, and receives downlink data according to the scheduling signaling. The method provides a way of measuring and feeding back CSI with reduced CSI-RS overhead. The method can configure DMRS ports in a flexible manner. Therefore, performances of MU-MIMO can be optimized.
1. A method of a user equipment (UE), the method comprising:
receiving configuration information related to a channel state information (CSI) process, the configuration information comprising configuration information of N non-zero power (NZP) channel state information reference signal (CSI-RS) resources; and
measuring a channel state based on the configuration information,
wherein the CSI process is associated with multiple NZP CSI-RS resources,
wherein the UE assumes reference physical downlink shared channel (PDSCH) transmission power corresponding to the multiple NZP CSI-RS resources based on at least one parameter configured via higher layer signaling for measuring the channel state for the CSI process based on the multiple NZP CSI-RS resources,
wherein the at least one parameter includes P c which is an assumed ratio of PDSCH energy per resource element (EPRE) to NZP CSI-RS EPRE, and
wherein the higher layer signaling comprises the P c of the reference PDSCH transmission power configured for the N NZP CSI-RS resources.
2. The method of claim 1 , further comprising:
measuring interference based on one zero power (ZP) CSI interference measurement (CSI-IM) resource.
3. The method of claim 1 , further comprising:
receiving scheduling information from a base station; and
receiving downlink data based on the scheduling information.
4. The method of claim 3 , wherein:
the scheduling information comprises information of de-modulation reference signal (DMRS) ports allocated to the UE, a number of data transmission layers and a number of resource element (RE) collections occupied by DMRSs,
the UE receives the DMRSs based on the allocated DMRS ports and the number of data transmission layers,
DMRS ports 7-10 are used for supporting multi-user multiple input multiple output (MU-MIMO) transmission of the DMRSs, and
the UE receives a PDSCH from an RE collection of port 9 when the DMRSs are transmitted using an RE collection of port 7.
5. The method of claim 3 , further comprising:
increasing a length of a time-expanded Walsh code to support multi-user multiple input multiple output (MU-MIMO) transmission of de-modulation reference signals (DMRSs) signals, DMRS ports having best orthogonality among all of DMRS ports that support MU-MIMO are allocated to different layers of the UE or to different UEs,
wherein the scheduling information comprises information of DMRS ports allocated to the UE and the number of data transmission layers.
6. The method of claim 1 , wherein measuring the channel state comprises:
measuring channel characteristics of a two-dimensional antenna array on an axis x and an axis y respectively,
wherein the axis x and the axis y are directions respectively corresponding to two dimensions of the two-dimensional antenna array.
7. The method of claim 6 , wherein receiving the configuration information comprises:
receiving CSI-RS signals via NZP CSI-RS ports on which channel characteristics on the axis x and the axis y are measured,
wherein an NZP CSI-RS signal for measuring the channel characteristics on the axis x and the axis y is received from one NZP CSI-RS port for a shared antenna unit on the axis x and the axis y, and an NZP CSI-RS signal for measuring channel characteristics of another antenna unit is received from the other NZP CSI-RS port for the shared antenna unit.
8. The method of claim 6 , wherein antenna units in a cross-polarized two-dimensional antenna array are divided into two groups according to polarization directions,
wherein the configuration information comprises configuration information of NZP CSI-RS ports corresponding to each group of antenna units having the same polarization direction, and
wherein the two groups of antenna units are configured with the same number of NZP CSI-RS ports.
9. The method of claim 1 , further comprising:
reporting a pre-coding matrix indicator (PMI) and information of a phase between each pair of PMIs.
10. The method of claim 1 ,
wherein the P c corresponds to an index k, k is the index of each NZP CSI-RS resource, k=0, 1, . . . N−1, and N is an integer larger than 2, and
wherein the UE assumes the reference PDSCH transmission power based on the P c when measuring CSI based on the k th NZP CSI-RS resource.
11. The method of claim 1 , wherein the UE calculates the reference PDSCH transmission power corresponding to a portion of the multiple NZP CSI-RS resources based on a pre-set assumption of the reference PDSCH transmission power, and
wherein the channel state is measured based on a portion of the multiple NZP CSI-RS resources without using an assumption of the reference PDSCH transmission power.
12. A user equipment (UE) for data processing, the UE comprising:
a transceiver configured to receive configuration information related to a channel state information (CSI) process from a base station (BS), the configuration information comprising configuration information of N non-zero power (NZP) channel state information reference signal (CSI-RS) resources; and
at least one processor configured to measure a channel state based on the configuration information,
wherein the CSI process is associated with multiple NZP CSI-RS resources,
wherein the UE assumes reference physical downlink shared channel (PDSCH) transmission power corresponding to the multiple NZP CSI-RS resources based on at least one parameter configured via higher layer signaling for measuring the channel state for the CSI process based on the multiple NZP CSI-RS resources,
wherein the at least one parameter includes P c which is an assumed ratio of PDSCH energy per resource element (EPRE) to NZP CSI-RS EPRE, and
wherein the higher layer signaling comprises the Pc of the reference PDSCH transmission power configured for the N NZP CSI-RS resources.
13. The UE of claim 12 , wherein the UE measures interference based on one zero power (ZP) CSI interference measurement (CSI-IM) resource.
14. The UE of claim 12 , further comprising:
a scheduler configured to receive scheduling information from the base station, receives downlink data based on the scheduling information.
15. The UE of claim 14 , wherein the scheduling information comprises information of de-modulation reference signal (DMRS) ports allocated to the UE, the number of data transmission layers, and
wherein the UE increases the length of a time-expanded Walsh code to support MU-MIMO transmission of DMRS signals, and the DMRS ports having best orthogonality among all of DMRS ports that support MU-MIMO are allocated to different layers of the UE or to different UEs.
16. The UE of claim 12 ,
wherein the P c corresponds to an index k, k is the index of each NZP CSI-RS resource, k=0, 1, . . . N−1, and N is an integer larger than 2, and
wherein the UE assumes the reference PDSCH transmission power based on P c when measuring CSI based on the k th NZP CSI-RS resource.