Multi-User (MU) Multiple-Input and Multiple-Output (MIMO) Enhancement

• US 20140198750A1
• Filed: 01/15/2014
• Published: 07/17/2014
• Est. Priority Date: 01/17/2013
• Status: Abandoned Application

• Current Assignee: NEC Laboratories America Inc (NEC Corporation)
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Prasad, Narayan, Yue, Guosen, Rangarajan, Sampath
• Application Number:
  US14/156,043
• Publication Number:
  US 20140198750A1
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/021 Estimation of channel covariance
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/03923 according to the rank
• CPC Class Codes: H04L 25/03949 equalizer selection or adaptation based on feedback multiple signaling inclusive of a precoding command for adapting the transmitter H04L1/0031; feedback for transmit diversity systems H04B7/0619; selection of codebook or precoding matrix for MIMO diversity systems H04B7/0456
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• 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

Abstract

A method implemented in a base station used in a mobile communications system is disclosed. The method includes configuring for a user equipment (UE) a channel state information (CSI) process for multi-user (MU) multiple-input and multiple-output (MIMO), the CSI process for MU-MIMO being associated with a channel part and an interference part, and according to the interference part, configuring the UE to measure or estimate inter-cell interference (ICI) and to compute or estimate intra-cell interference. Other apparatuses, systems, and methods also are disclosed.

Claims

1. A method implemented in a base station used in a mobile communications system, the method comprising:

configuring for a user equipment (UE) a channel state information (CSI) process for multi-user (MU) multiple-input and multiple-output (MIMO), the CSI process for MU-MIMO being associated with a channel part and an interference part; and

according to the interference part, configuring the UE to measure or estimate inter-cell interference (ICI) and to compute or estimate intra-cell interference.

2. The method as in claim 1,

wherein the channel part represents a channel seen from a serving transmission point (TP).

3. The method as in claim 1,

wherein, for the channel part, a channel estimate is obtained using a non-zero power (NZP) CSI reference signal (RS) resource.

4. The method as in claim 1,

wherein the interference part is associated with a zero-power (ZP) CSI reference signal (RS) resource in an interference measurement resource (IMR).

5. The method as in claim 1,

wherein the CSI process for MU-MIMO defines multiple intervals over which the UE reports CSI.

6. The method as in claim 5,

wherein a sequence of intervals containing a non-zero power (NZP) CSI reference signal (RS) resource is configured along with a sequence containing an interference measurement resource (IMR), and

wherein each set of IMR resource elements (REs) is associated with a set of NZP-CSI-RS REs.

7. The method as in claim 1, further comprising:

configuring for the UE a CSI process for single-user (SU) multiple-input and multiple-output (MIMO), the CSI process for SU-MIMO being associated to the channel part and the interference part.

8. The method as in claim 1,

wherein the mobile communications system allows multiple CSI processes including the CSI process for MU-MIMO.

9. The method as in claim 8,

wherein the number of the multiple CSI processes is two.

10. The method as in claim 1,

wherein the intra-cell interference is emulated using a precoder or an indication of the precoder determined for a reference baseline CSI process and by assuming that intra-cell interfering signals are isotropically distributed in a subspace of the M_t dimensional vector space ^Mt, where M_t denotes the number of transmit antennas at a serving transmission point (TP).

11. The method as in claim 1,

wherein the intra-cell interference is emulated by using a precoder or an indication of the precoder determined for a reference baseline CSI process and by assuming interfering vectors to be uniformly distributed in a pre-determined precoder codebook subset.

12. The method as in claim 1,

wherein the UE follows a rule to obtain a second precoder or an indication of the second precoder from a first precoder or an indication of the first precoder determined for a reference baseline CSI process to emulate the intra-cell interference.

13. The method as in claim 1,

wherein the UE reports MU-CSI including a precoding matrix indicator (PMI) and a channel quality indicator (CQI) or a signal-to-interference-plus-noise ratio (SINR) by checking each precoder in another subset configured semi-statically for the CSI process for MU-MIMO, performing the intra-cell interference emulation for each precoder, and computing an MU-SINR.

14. The method as in claim 1,

wherein the UE assumes a first precoder or an indication of the first precoder determined for a reference baseline CSI process and a second precoder or an indication of the second precoder for the intra-cell interference,

wherein a power scaling factor for interference is semi-statically configured, and

wherein the UE reports a second PMI and an MU signal-to-interference-plus-noise ratio (SINR).

15. The method as in claim 14, further comprising:

configuring and conveying a specific codebook subset semi-statically to the UE,

wherein the UE assumes the specific codebook subset in search for the second precoder, and

wherein the specific codebook subset varies depending on the first precoder.

16. The method as in claim 1,

wherein the CSI process for MU-MIMO specifies a rule where a precoder or an indication of the precoder in a reference baseline CSI process is first used to identify a codebook subset, and

wherein a single-user (SU) multiple-input and multiple-output (MIMO) rule is followed to determine a precoding matrix indicator (PMI) and a signal-to-interference-plus-noise ratio (SINR) in the codebook subset.

17. The method as in claim 16, further comprising:

configuring and conveying the codebook subset semi-statically to the UE,

wherein the specific codebook subset varies depending on a reference PMI.

18. A method implemented in a user equipment (UE) used in a mobile communications system, the method comprising:

receiving a channel state information (CSI) process for multi-user (MU) multiple-input and multiple-output (MIMO), the CSI process for MU-MIMO being associated with a channel part and an interference part; and

according to the interference part, measuring or estimate inter-cell interference (ICI) and to compute or estimate intra-cell interference.

19. A mobile communications system comprising:

a user equipment (UE); and

a base station configuring for a user equipment (UE) a channel state information (CSI) process for multi-user (MU) multiple-input and multiple-output (MIMO), the CSI process for MU-MIMO being associated with a channel part and an interference part,

wherein, according to the interference part, the UE is configured to measure or estimate inter-cell interference (ICI) and to compute or estimate intra-cell interference.