Supporting measurments and feedback for 3D MIMO with data transmission optimization

• US 9,225,478 B2
• Filed: 12/27/2012
• Issued: 12/29/2015
• Est. Priority Date: 07/02/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Chen, Xiaogang, Davydov, Alexei, Li, Qinghua, Zhu, Yuan, Morozov, Gregory V., Fwu, Jong-Kae, Han, Seunghee, Niu, Huaning, Yang, Rongzhen
• Primary Examiner(s): PHAN, MAN U
• Application Number:
  US13/728,778
• Publication Number:
  US 20140003240A1
• Time in Patent Office: 1,097 Days
• Field of Search: 370235-253, 370255-252, 370328-345, 375267-295, 455450-562, 455423-446, 342373-379
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1628 List acknowledgements, i.e. the acknowledgement message consisting of a list of identifiers, e.g. of sequence numbers H04L1/1614 takes precedence
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1861 Physical mapping arrangements for ACK signaling see also H04L5/0053
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 28/0205 at the air interface dynamic wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/08 Load balancing or load distribution transferring a connection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: H04W 52/0209 in terminal devices terminal devices per se H04W88/02
• CPC Class Codes: H04W 52/0212 : managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/0245 : according to signal strength
• CPC Class Codes: H04W 52/383 : power control in peer-to-peer links
• CPC Class Codes: H04W 68/00 : User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 72/0446 : Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/046 : the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/30 : Resource management for broadcast services
• CPC Class Codes: H04W 88/08 : Access point devices
• CPC Class Codes: H04W 92/02 : Inter-networking arrangements
• CPC Class Codes: Y02D 30/70 : in wireless communication networks
• CPC Class Codes: Y02E 40/60 : Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Abstract

Technology is discussed for supporting wireless communication paths from an antenna array with a vertical directional component. Examples reduce training feedback for increased numbers of communication paths by only reporting on a subset of Reference Signals (RSs) provided for various vertical beam configurations. Additional examples reduce feedback with virtual measurements based on a difference between RS measurements. One such measurement can come from full set of RSs for a reference beam configuration and another from a partial set of RSs for an additional beam configuration. Such virtual measurements can also be based on cross correlation for beamforming weights associated with the two configurations. Several examples of preparing and sending measurement reports consistent with Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) standards are discussed. The supporting technology also increases diversity and reduces a power differential between spatially multiplexed layers transmitting a common codeword.

Claims

1. A device for reducing feedback overhead associated with multiple vertical beams from a two-dimensional antenna array having a plurality of rows of antenna elements and a plurality of columns of antenna elements for wireless communication, comprising:

a receive module, at a User Equipment (UE), configured to receive multiple Channel State Information-Reference Signal (CSI-RS) resources, wherein a CSI-RS resource corresponds to one of multiple vertical beam configurations associated with the plurality of columns of antenna elements; and

a selection module, at the UE, configured to select a subset of multiple vertical beam configurations for which to provide CSI-RS reports to reduce a number of CSI-RS reports, leaving a set of non-selected CSI-RS resources unreported; and

a preparation module, at the UE, configured to prepare at least one CSI-RS report for the subset of multiple vertical beam configurations; and

a reporting module, at the UE, to send the at least one CSI-RS report to an evolved Node B (eNodeB), wherein the two-dimensional antenna array, including the plurality of rows of antenna elements and the plurality of columns of antenna elements, is located at the eNodeB.

2. The device of claim 1, wherein the selection module selects the subset of multiple vertical beam configurations based on a superior spectral efficiency.

3. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to multiple antenna ports that comprise one of two and four antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, one of;

both a CSI reporting type 5a message and a CSI reporting type 2 message, the CSI reporting type 5a message carrying a Rank Indicator (RI) and a CSI-RS indicator which recommends a best CSI-RS resource based on a superior spectral efficiency, the CSI reporting type 2 message carrying a Precoding Matrix Indicator (PMI) and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator, and

both a CSI reporting type 3 message and a CSI reporting type 2d message, the CSI reporting type 3 message carrying an RI, the CSI reporting type 2d message carrying a CSI-RS indicator, a PMI, and a CQI.

4. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, one of;

both a CSI reporting type 5a message and a CSI reporting type 2c message, the CSI reporting type 5a message carrying a Rank Indicator (RI) and a CSI-RS indicator which recommends a best CSI-RS resource based on a superior spectral efficiency, the CSI reporting type 2c message carrying a first Precoding Matrix Indicator (PMI), a second PMI and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator; and

each of a CSI reporting type 3 message, a CSI reporting type 2e message, and a CSI reporting type 4 message, the CSI reporting type 3 message carrying an RI, the CSI reporting type 2e message carrying a CSI-RS indicator, a first PMI, and a second PMI for the best CSI-RS resource recommended by the CSI-RS indicator, and the CSI reporting type 4 message carrying a CQI.

5. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, one of;

both a CSI reporting type 5 message and a CSI reporting type 2f message, the CSI reporting type 5 message carrying a Rank Indicator (RI) and a first Precoding Matrix Indicator (PMI), the CSI reporting type 2f message carrying a CSI-RS indicator, a second PMI for a best CSI-RS resource recommended by the CSI-RS indicator, and a CQI; and

both a CSI reporting type 5a message and a CSI reporting type 2b message, the CSI reporting type 5a message carrying an RI, a first PMI, and a CSI-RS indicator, the CSI reporting type 2b message carrying a second PMI for a best CSI-RS resource recommended by the CSI-RS indicator and a CQI.

6. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, each of a CSI reporting type 7 message, a CSI reporting type 5 message, and a CSI reporting type 2b message, wherein;

the CSI reporting type 7 message carries a CSI-RS indicator and has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead,

the CSI reporting type 5 message carries an RI and a first Precoding Matrix Indicator (PMI) for a best CSI-RS resource recommended by the CSI-RS indicator, and

the CSI reporting type 2b message carries a second PMI and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI.

7. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to multiple antenna ports that comprise one of two and four antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, one of;

each of a CSI reporting type 5a message, a CSI reporting type 2 message, and a CSI reporting type 1 message, the CSI reporting type 5a message carrying a Rank Indicator (RI) and a CSI-RS indicator which recommends a best CSI-RS resource based on a superior spectral efficiency, the CSI reporting type 2 message carrying a Precoding Matrix Indicator (PMI) and a Wide Band Channel Quality Indicator (WBCQI) for the best CSI-RS resource recommended by the CSI-RS indicator, the CSI reporting type 1 message carrying a sub-band Channel Quality Indicator (CQI); and

each of a CSI reporting type 3 message, a CSI reporting type 2d message, and a CSI reporting type 1 message, the CSI reporting type 3 message carrying a Rank Indicator (RI), the CSI reporting type 2d message carrying a CSI-RS indicator, a PMI, and a WBCQI for a best CSI-RS resource recommended by the CSI-RS indicator, the CSI reporting type 1 message carrying a sub-band CQI.

8. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, one of;

each of a CSI reporting type 2a message, a CSI reporting type 2b message, a CSI reporting type 1 message, and a CSI reporting type 6a message, the CSI reporting type 2a message carrying a first Precoding Matrix Indicator (PMI), the CSI reporting type 2b message carrying a second PMI and a Wide Band Channel Quality Indicator (WBCQI), the CSI reporting type 1 message carrying a sub-band Channel Quality Indicator (CQI), and the CSI reporting type 6a message carrying a Rank Indicator (RI), a CSI-RS indicator and a Precoding Type Indicator (PTI), and

each of a CSI reporting type 2g message, a CSI reporting type 2b message, a CSI reporting type 1 message, and a CSI reporting type 6 message, the CSI reporting type 2g message carrying a first PMI and a CSI-RS indicator, the CSI reporting type 2b message carrying a second PMI and a WBCQI, the CSI reporting type 1 message carrying a sub-band CQI, and the CSI reporting type 6 message carrying a Rank Indicator (RI) and a PTI.

9. The device of claim 1, wherein:

the at least one CSI-RS report is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

the reporting module reports the at least one CSI-RS report by sending, to the eNodeB, each of a CSI reporting type 7 message, a CSI reporting type 6 message, a CSI reporting type 2a message, a CSI reporting type 2b message, and a CSI reporting type 1a message, wherein;

the CSI reporting type 7 message carries a CSI-RS indicator and has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead,

the CSI reporting type 6 message carries an RI, and a Precoding Type Indicator (PTI) for the recommended CSI-RS resource,

the CSI reporting type 2a message carries a first Precoding Matrix Indicator (PMI),

the CSI reporting type 2b message carries a second PMI and a Wide Band Channel Quality Indicator (WBCQI), and

the CSI reporting type 1 message carries a sub-band Channel Quality Indicator (CQI).

10. The device of claim 1, wherein the reporting module reports at least one CSI-RS report by sending, to the eNodeB, each of a CSI reporting type 7 message, a CSI reporting type 3 message, and one of a CSI reporting type 2 message and a CSI reporting type 2c message, wherein:

the CSI reporting type 7 message carries a CSI-RS indicator that recommends a best CSI-RS resource based on a superior spectral efficiency and has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead;

the CSI reporting type 3 message carries an RI for the best CSI-RS resource recommended by the CSI-RS indicator;

the CSI reporting type 2 message carries a Precoding Matrix Indicator (PMI) and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI; and

the CSI reporting type 2c message carries a first Precoding Matrix Indicator (PMI), a second PMI, and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI.

11. The device of claim 1, wherein the multiple vertical beam configurations have the same number of ports and share a common codebook at the UE.

12. A method for reducing feedback overhead for multiple vertical beams from a two-dimensional antenna array having a plurality of rows of antenna elements and a plurality of columns of antenna elements for wireless communication, comprising:

receiving, at a User Equipment (UE) from an evolved Node B (eNodeB);

reference Channel State Information-Reference Signal (CSI-RS) resources configured for a first full set of antenna ports for a first vertical beam configuration associated with the plurality of columns of antenna elements, and

a set of additional CSI-RS resources configured for at least one subset of a second full set of antenna ports for an additional vertical beam configuration associated with the plurality of columns of antenna elements, wherein the two-dimensional antenna array, including the plurality of rows of antenna elements and the plurality of columns of antenna elements, is located at the eNodeB;

measuring reference channel response information for the reference CSI-RS resources and additional channel response information for the set of additional CSI-RS resources; and

calculating an offset between the first vertical beam configuration and the additional vertical beam configuration with the reference channel response information and the additional channel response information.

13. The method of claim 12, wherein calculating the offset further comprises calculating a difference between the reference channel response information for the reference CSI-RS resources configured for the first full set of antenna ports and the additional channel response information for the set of additional CSI-RS resources configured for the subset of the second full set of antenna ports, where the offset is measured in decibels (dBs).

14. The method of claim 12, further comprising:

receiving vertical beamforming weights for the first vertical beam configuration over one of Layer 1 (L1), Layer 2 (L2), and Radio Resource Control (RRC) signaling in order to assist in vertical beamforming gain compensation;

selecting a best vertical Precoding Matrix Indicator (PMI) for the additional channel response information corresponding to the set of additional CSI-RS resources;

determining beamforming weights of the best vertical PMI;

calculating a cross correlation between the vertical beamforming weights and the beamforming weights of the best vertical PMI, and

assigning the offset based on the cross correlation.

15. The method of claim 14, wherein assigning the offset further comprises assigning a value to the offset equal to the cross correlation between the vertical beamforming weights of the first vertical beam configuration and the beamforming weights of the best vertical PMI for the second set of CSI-RS resources, wherein a cross correlation of 0 results in assigning a predetermined vertical beamforming gain value.

16. The method of claim 12, further comprising calculating a unit of virtual channel response information for the additional vertical beam configuration by adding the offset to at least one unit of channel response information measured with respect to the reference CSI-RS resources for the first vertical beam configuration for at least one antenna port.

17. The method of claim 16, further comprising reporting the unit of virtual channel response information to the eNodeB.

18. The method of claim 17, wherein:

the unit of virtual channel response information is configured with respect to multiple antenna ports that comprise one of two and four antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

reporting the unit of virtual channel response information comprises sending one of;

both a CSI reporting type 5a message and a CSI reporting type 2 message, the CSI reporting type 5a message carrying a Rank Indicator (RI) and a CSI-RS indicator which recommends a best CSI-RS resource based on a superior spectral efficiency, the CSI reporting type 2 message carrying a Precoding Matrix Indicator (PMI) and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator, and

both a CSI reporting type 3 message and a CSI reporting type 2d message, the CSI reporting type 3 message carrying an RI, the CSI reporting type 2d message carrying a CSI-RS indicator, a PMI, and a CQI.

19. The method of claim 17, wherein:

the unit of virtual channel response information is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 1-1; and

reporting the unit of virtual channel response information comprises sending each of a CSI reporting type 7 message, a CSI reporting type 5 message, and a CSI reporting type 2b message, wherein;

the CSI reporting type 7 message carries a CSI-RS indicator and has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead,

the CSI reporting type 5 message carries an RI and a first Precoding Matrix Indicator (PMI) for a best CSI-RS resource recommended by the CSI-RS indicator, and

the CSI reporting type 2b message carries a second PMI and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI.

20. The method of claim 17, wherein:

the unit of virtual channel response information is configured with respect to multiple antenna ports that comprise one of two and four antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

reporting the unit of virtual channel response information comprises sending one of;

each of a CSI reporting type 5a message, a CSI reporting type 2 message, and a CSI reporting type 1 message, the CSI reporting type 5a message carrying a Rank Indicator (RI) and a CSI-RS indicator which recommends a best CSI-RS resource based on a superior spectral efficiency, the CSI reporting type 2 message carrying a Precoding Matrix Indicator (PMI) and a Wide Band Channel Quality Indicator (WBCQI) for the best CSI-RS resource recommended by the CSI-RS indicator, the CSI reporting type 1 message carrying a sub-band Channel Quality Indicator (CQI); and

each of a CSI reporting type 3 message, a CSI reporting type 2d message, and a CSI reporting type 1 message, the CSI reporting type 3 message carrying a Rank Indicator (RI), the CSI reporting type 2d message carrying a CSI-RS indicator, a PMI, and a WBCQI for a best CSI-RS resource recommended by the CSI-RS indicator, the CSI reporting type 1 message carrying a sub-band CQI.

21. The method of claim 17, wherein:

the unit of virtual channel response information is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

reporting the unit of virtual channel response information comprises sending one of;

each of a CSI reporting type 2a message, a CSI reporting type 2b message, a CSI reporting type 1 message, and a CSI reporting type 6a message, the CSI reporting type 2a message carrying a first Precoding Matrix Indicator (PMI), the CSI reporting type 2b message carrying a second PMI and a Wide Band Channel Quality Indicator (WBCQI), the CSI reporting type 1 message carrying a sub-band Channel Quality Indicator (CQI), and the CSI reporting type 6a message carrying a Rank Indicator (RI), a CSI-RS indicator and a Precoding Type Indicator (PTI), and

each of a CSI reporting type 2g message, a CSI reporting type 2b message, a CSI reporting type 1 message, and a CSI reporting type 6 message, the CSI reporting type 2g message carrying a first PMI and a CSI-RS indicator, the CSI reporting type 2b message carrying a second PMI and a WBCQI, the CSI reporting type 1 message carrying a sub-band CQI, and the CSI reporting type 6 message carrying a Rank Indicator (RI) and a PTI.

22. The method of claim 17, wherein:

the unit of virtual channel response information is configured with respect to eight antenna ports for a Physical Uplink Control CHannel (PUCCH) of mode 2-1; and

reporting the unit of virtual channel response information comprises sending each of a CSI reporting type 7 message, a CSI reporting type 6 message, a CSI reporting type 2a message, a CSI reporting type 2b message, and a CSI reporting type 1a message, wherein;

the CSI reporting type 7 message carries a CSI-RS indicator and that has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead,

the CSI reporting type 6 message carries an RI, and a Precoding Type Indicator (PTI) for the recommended CSI-RS resource,

the CSI reporting type 2a message carries a first Precoding Matrix Indicator (PMI),

the CSI reporting type 2b message carries a second PMI and a Wide Band Channel Quality Indicator (WBCQI), and

the CSI reporting type 1 message carries a sub-band Channel Quality Indicator (CQI).

23. The method of claim 17, wherein reporting the unit of virtual channel response information comprises sending each of a CSI reporting type 7 message, a CSI reporting type 3 message, and one of a CSI reporting type 2 message and a CSI reporting type 2c message, wherein:

the CSI reporting type 7 message carries a CSI-RS indicator that recommends a best CSI-RS resource based on a superior spectral efficiency and has a periodicity that is one of equal to and a multiple of a Rank Indicator (RI) periodicity, making use of a relatively slow variability with respect to vertical CSI to reduce overhead;

the CSI reporting type 3 message carries an RI for the best CSI-RS resource recommended by the CSI-RS indicator;

the CSI reporting type 2 message carries a Precoding Matrix Indicator (PMI) and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI; and

the CSI reporting type 2c message carries a first Precoding Matrix Indicator (PMI), a second PMI, and a Channel Quality Indicator (CQI) for the best CSI-RS resource recommended by the CSI-RS indicator and conditioned on the RI.

24. A computer program product comprising at least one non-transitory computer usable medium having a computer readable program code embodied therein to implement instructions for a method for reducing a power differential between multiple spatial multiplexing layers transmitting a common codeword, comprising:

generating a column vector, at an evolved Node B (eNodeB), with multiple symbols from a common codeword, wherein the column vector has a length equal to a Rank Indicator (RI) and each symbol in the column vector is assigned to a spatial multiplexing layer, wherein vertical beam forming increases a number of spatial multiplexing layers transmitted from the eNodeB and the vertical beamforming is performed using an antenna array having a plurality of rows of antenna elements and a plurality of columns of antenna elements, wherein the two-dimensional antenna array, including the plurality of rows of antenna elements and the plurality of columns of antenna elements, is located at the eNodeB;

multiplying the column vector by a rotation matrix, wherein the rotation matrix combines symbols from the common codeword to equalize transmission signals among the symbols from the common codeword to reduce differences arising from differing characteristics in multiple spatial multiplexing layers for the symbols from the common codeword; and

multiplying by a precoding matrix so that the symbols in the column vector are prepared for transmission from the eNodeB to a User Equipment (UE).

25. The computer program product of claim 24 further comprising multiplying by a Cyclic Delay Diversity (CDD) matrix to provide spatial diversity to symbols in the column vector.

26. The computer program product of claim 25, wherein the CDD matrix combines symbols within the column vector from the common codeword while preventing a symbol from the column vector from a different codeword from being combined with a symbol from the common codeword.

27. The computer program product of claim 24, wherein the rotation matrix combines symbols within the column vector for each of at least two differing codewords while preventing symbols from differing codewords from being combined.

28. The computer program product of claim 24, further comprising including a Reference Signal (RS) in the common codeword.

29. The computer program product of claim 28, wherein the RS is one of a User-Equipment-specific RS (UERS) and a Cell-specific RS (CRS), enabling a more accurate calculation of a Channel Quality Indicator (CQI) by a User Equipment (UE) by reducing errors arising from differences in spatial multiplexing layers.