WO2018040074A1

WO2018040074A1 - Methods, base stations, and user equipments for multi-user mimo co-scheduling with interference measurement

Info

Publication number: WO2018040074A1
Application number: PCT/CN2016/097976
Authority: WO
Inventors: Yaming LUO; Xiang Chen; Eddy Chiu
Original assignee: Huizhou Tcl Mobile Communication Co.,Ltd
Priority date: 2016-09-02
Filing date: 2016-09-02
Publication date: 2018-03-08
Also published as: CN109314556B; CN109314556A

Abstract

Methods for multi-user MIMO co-scheduling with interference measurement are disclosed. A method includes: transmitting a first RS to a UE; receiving a first CSI feedback from the UE as the UE measures the first RS; transmitting initial co-scheduling information and a second RS to the UE, the initial co-scheduling comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by Spatial Multiplexing (SM) in the data transmission, the initial co-scheduling information being derived based on the first CSI; receiving a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object; and adjusting the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information. The method can be applied to Full-Dimension MIMO. Associated base stations and UEs are also disclosed.

Description

METHODS, BASE STATIONS, AND USER EQUIPMENTS FOR MULTI-USER MIMO CO-SCHEDULING WITH INTERFERENCE MEASUREMENT

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to communications, and in particular relate to methods, base stations, and User Equipments (UEs) for multi-user co-scheduling.

BACKGROUND

Multiple-Input and Multiple-Output (MIMO) is a method for multiplying the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation.

MIMO supports Single-User MIMO (SU-MIMO) and Multi-User MIMO (MU-MIMO) . In SU-MIMO, the spatially multiplexed data streams are scheduled to one single user to improve the transmission rate and spectrum efficiency for the user. In MU-MIMO, the spatially multiplexed data streams are scheduled to multiple users, which will share the same time-frequency resources by spatial multiplexing (SM) in the data transmission, so the system can achieve additional multi-user diversity gain through multi-user scheduling in spatial dimensions. Since multiple UEs use the same time-frequency resources by SM, this requires the use of multiple transmit antennas at the base station/eNodeB to distinguish two or more transmissions. Furthermore, MU-MIMO typically requires more accurate Channel State Information (CSI) feedback.

UE may measure a downlink Reference Signal (RS) from the base station to obtain the CSI and report it to the eNodeB (eNB) . The eNB may schedule the UE and precode the data signal based on the CSI feedback. In MU-MIMO, the CSI information is better to further include interference, which requires the UE to have knowledge of object (s) to which it is co-scheduled (i.e., object (s) which use the same time-frequency resource as the UE by SM) , which in turn makes it difficult to obtain accurate CSI information.

If the co-scheduling result is not determined by base station, the UE can either report all the possible co-scheduling cases, or determines a co-scheduling on itself. For the first case the overhead of the resulted measurement report can be large, while for the second case, because the UE cannot directly acquire the co-scheduling result other UEs acquire, the decisions different UEs make are probable to conflict. On the other hand, if the base station determines the co-scheduled object (s) and informs the relevant information to the UE while transmitting the downlink RS, because the base station hasn’ t so far received any CSI feedback, the co-scheduled object (s) as decided may be inaccurate, for example, there may exist serious interference between the UE and some co-scheduled object. In both cases the accurate UE scheduling can be awkward, thus affecting the system performance in subsequent data transmission.

SUMMARY

Embodiments of the present disclosure provide methods, base stations, and UEs for multi-user co-scheduling, which can solve the difficulty in the prior art of obtaining accurate CSI information in MU-MIMO.

There is provided a method for multi-user co-scheduling that comprises: transmitting a first RS to a UE； receiving a first CSI feedback from the UE as the UE measures the first RS； transmitting initial co-scheduling information and a second RS to the UE, the initial co-scheduling comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； receiving a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and adjusting the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Adjusting the initial co-scheduling information according to the second CSI may comprise: removing from the initial co-scheduling information the identifier of at least one co-scheduled object that is found in the second CSI, the overall interference level including the at least one co-scheduled object to the UE lying beyond a preset range.

Adjusting the initial co-scheduling information according to the second CSI may further comprise: adding to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

The indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) .

The second CSI may further comprise co-scheduled objects modification recommendation information. Adjusting the initial co-scheduling information according to the second CSI may comprise: adding or removing the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduling objects modification recommendation information.

The method may further comprise: receiving aperiodic co-scheduling objects modification recommendation information from the UE； and adding or removing the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduling objects modification recommendation information to obtain refined co-scheduling information.

The method may further comprise, before receiving the aperiodic co-scheduled objects modification recommendation information: transmitting signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information.

The method may further comprise: transmitting data based on the refined co-scheduling information or the initial co-scheduling information, wherein in the case the data may be transmitted based on the initial co-scheduling information, the refined co-scheduling information may be used for the data transmission of the next cycle.

The method may further comprise: transmitting signaling to the UE to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information.

The method may further comprise: transmitting a preset range to the UE, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

The second RS may be different from the first RS, and the second RS may be generated based on the first CSI.

The second RS may be carried by at least two beams formed through beamforming, and a port virtualization matrix among the mapping matrices used by the beamforming for at least one beam may be the same as Precoding Matrix Information (PMI) in the first CSI.

The second RS may serve as the first RS of the next cycle, wherein the first RS of the next cycle may be omitted, and the initial co-scheduling information of the next cycle may be determined based on the second CSI /aperiodic co-scheduled objects modification recommendation information of one or more cycles prior to the next cycle.

The initial co-scheduling information may further comprise information of a beam selected for the UE； and/or the second CSI may comprise information of a beam the UE actively selects.

Each co-scheduled object may be a beam.

Different beams may correspond to different time-frequency resources.

The identifier of each co-scheduled object may comprise parameters of time-frequency resource corresponding to the co-scheduled object.

The initial co-scheduling information may be carried by CSI-RS-Config or CSI-IM-Config signaling.

There is also provided a method for multi-user co-scheduling that comprises: measuring, by a UE, a first RS from a base station to generate first CSI； transmitting, by the UE, the first CSI to the base station； receiving, by the UE, initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； measuring, by the UE, a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and transmitting, by the UE, the second CSI to the base station, so that the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

The indication of the interference level may comprise initial MU-CQI.

The indication of the interference level may further comprise refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Transmitting the second CSI to the base station may comprise: removing once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmitting the reduced second CSI to the base station.

The method may further comprise: transmitting to the base station aperiodic co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

The method may further comprise, before transmitting the aperiodic co-scheduled objects modification recommendation information: receiving from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information.

The method may further comprise: receiving the preset range from the base station, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

The method may further comprise, before transmitting the second CSI to the base station: receiving from the base station signaling that informs the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information； adjusting the second CSI based on the signaling.

The second RS may be carried by at least two beams formed through beamforming. The initial co-scheduling information may further comprise information of a beam selected for the UE. The second CSI may comprise information of a beam the UE actively selects.

The is also provided a base station that comprises: a first transmitting module configured to transmit a first RS to a UE； a first receiving module configured to receive a first CSI feedback from the UE as the UE measures the first RS； a second transmitting module configured to transmit initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； a second receiving module configured to receive a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and an adjustment module configured to adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

The adjustment module may be configured to remove from the initial co-scheduling information the identifier of at least one co-scheduled object that is found in the second CSI, the overall interference level including the at least one co-scheduled object to the UE lying beyond a preset range.

The adjustment module may further be configured to add to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the level of overall interference to the UE lies within the present range and which is not present in the initial co-scheduling information.

The indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information. The adjustment module may be configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.

The second RS may be different from the first RS. The second RS may be carried by at least two beams formed through beamforming, and a port virtualization matrix among the mapping matrices used by the beamforming for at least one beam may be the same as PMI in the first CSI.

There is also provided a UE that comprises: a first measurement module configured to measure a first RS from a base station to generate first CSI； a first transmitting module configured to transmit the first CSI to the base station； a first receiving module configured to receive initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； a second measurement module configured to measure a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and a second transmitting module configured to transmit the second CSI to the base station, so that the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

The indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

The second transmitting module may be configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit the reduced second CSI to the base station.

The UE may further comprise a third transmitting module configured to transmit to the base station aperiodic co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

There is also provided a base station that comprises a processor and a transceiver coupled to the processor. The processor may be configured to: transmit via the transceiver a first RS to a UE； receive a first CSI feedback from the UE as the UE measures the first RS； transmit via the transceiver initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； receive via the transceiver a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

The processor may be configured to remove from the initial co-scheduling information the identifier of at least one initial co-scheduled object that is found in the second CSI, the overall interference level including the at least one initial co-scheduled object to the UE lying beyond a preset range.

The processor may be configured to add to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

The indication of the interference level may further comprise refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information. The processor may be configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.

The processor may further be configured to receive via the transceiver aperiodic co-scheduled objects modification recommendation information from the UE；and add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the initial co-scheduling object adjustment recommendation information to obtain refined co-scheduling information.

The processor may further be configured to transmit via the transceiver signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information before receiving via the transceiver the aperiodic co-scheduled objects modification recommendation information.

The processor may further be configured to transmit data based on the refined co-scheduling information or the initial co-scheduling information, wherein in the case the data may be transmitted based on the initial co-scheduling information, the refined co-scheduling information may be used for the data transmission of the next cycle.

The processor may further be configured to transmit via the transceiver signaling to the UE to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information.

The processor may further be configured to transmit via the transceiver a preset range to the UE, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

The second RS may be carried by at least two beams formed through beamforming, and a port virtualization matrix among the mapping matrices used by the beamforming for at least one beam may be the same as PMI in the first CSI.

Each co-scheduled object may be a beam.

Different beams may correspond to different time-frequency resources.

The identifier of a co-scheduled object may comprise parameters of time-frequency resource corresponding to the co-scheduled object.

There is also provided a UE that comprises a processor and a communication circuit coupled to the processor. The processor may be configured to: measure via the communication circuit a first RS from a base station to generate first CSI； transmit via the communication circuit the first CSI to the base station； receive via the communication circuit initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, and the initial co-scheduling information being derived based on the first CSI； measure via the communication circuit a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and transmit via the communication circuit the second CSI to the base station, so that the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

The indication of the interference level may comprise initial MU-CQI.

The processor may be configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit via the communication circuit the reduced second CSI to the base station.

The processor may further be configured to transmit to the base station via the communication circuit aperiodic co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

The processor may further be configured to receive via the communication circuit from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information before transmit to the base station via the communication circuit aperiodic co-scheduled objects modification recommendation information.

The processor may further be configured to receive via the communication circuit the preset range from the base station, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

The processor may further be configured to receive via the communication circuit from the base station signaling that informs the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information； and adjust the second CSI based on the signaling before transmitting via the communication circuit the second CSI to the base station.

The second RS may be carried by at least two beams formed through beamforming. The initial co-scheduling information may comprise information of a beam selected for the UE. The second CSI may comprise information of a beam the UE actively selects.

Advantages of the present disclosure may follow. The base station may send twice the RS to the UE. The UE may measure a first RS and feedback first CSI, based on which the base station may perform initial scheduling and transmit the initial scheduling information and a second RS to the UE. The UE may measure the second RS at least based on the initial scheduling information to generate second CSI, and transmit the second CSI to the base station. The base station may then make further adjustments to the initial scheduling according to the second CSI to obtain refined scheduling. Compared with the prior art, the UE scheduling is centralized on the base station, avoiding potential conflicts between decisions different UEs make on their own. In addition, the decision-making uses the CSI the UE feeds back after measurement, so the scheduling accuracy is improved, resulting in enhanced system performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a first embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 2 is a flowchart illustrating a second embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 3 is a flowchart illustrating a third embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 4 is a flowchart illustrating a fourth embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 5 is a schematic diagram showing the beamforming for downlink data signal in Full-Dimension MIMO (FD-MIMO) .

FIG. 6 is a schematic diagram showing the base station transmitting non-precoded CSI-RS to UEs in an example of the fourth embodiment of the method for multi-user co-scheduling.

FIG. 7 is a schematic diagram showing the base station grouping UEs in an example of the fourth embodiment of the method for multi-user co-scheduling.

FIG. 8 is a schematic diagram illustrating refined co-scheduling in an example of the fourth embodiment of the method for multi-user co-scheduling.

FIG. 9 shows a simulation example for the fourth embodiment of the method for multi-user co-scheduling.

FIG. 10 shows another simulation example for the fourth embodiment of the method for multi-user co-scheduling.

FIG. 11 shows yet another simulation example for the fourth embodiment of the method for multi-user co-scheduling.

FIG. 12 shows still another simulation example for the fourth embodiment of the method for multi-user co-scheduling.

FIG. 13 shows still another simulation example for the fourth embodiment of the method for multi-user co-scheduling.

FIG. 14 is a flowchart illustrating a fifth embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 15 is a flowchart illustrating a sixth embodiment of a method for multi-user co-scheduling according to the disclosure.

FIG. 16 is a block diagram of a first embodiment of a base station according to the disclosure.

FIG. 17 shows a block diagram of a second embodiment of a base station according to the disclosure.

FIG. 18 shows a block diagram of a first embodiment of a UE according to the disclosure.

FIG. 19 shows a block diagram of a second embodiment of a UE according to the disclosure.

FIG. 20 shows a block diagram of a third embodiment of a UE according to the disclosure.

This disclosure includes references to “one embodiment, ” “a particular embodiment, ” “some embodiments, ” “various embodiments, ” or “an embodiment. ” The appearances of the phrases “in one embodiment, ” “in a particular embodiment, ” “in some embodiments, ” “in various embodiments, ” or “in an embodiment, ” do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

Various modules, units, circuits, or other components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the modules/units/circuits/components include structure (e.g., circuitry) that performs those task or tasks during operation. As such, the modules/units/circuits/components can be said to be configured to perform the task even when the specified module/unit/circuit/component is not currently operational (e.g., is not on) . The modules/units/circuits/components used with the “'configured to” language include hardware—for example, circuits, memory storing program instructions executable to implement the operation, etc. Reciting that a module/unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. §112 (f) , for that module/unit/circuit/component. Additionally, “configured to” can include a generic structure (e.g., generic circuitry) that is manipulated by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in a manner that is capable of performing the task (s) at issue. “Configured to” may also include adapting a manufacturing process (e.g., a semiconductor fabrication facility) to fabricate devices (e.g., integrated circuits) that are adapted to implement or perform one or more tasks.

As used herein, the term “based on” describes one or more factors that affect a determination. This term does not foreclose additional factors that may affect the determination. That is, a determination may be solely based on those factors or based, at least in part, on those factors. Consider the phrase “determine A based on B. ” While in this case, B is a factor affects the determination of A, such a phrase does not foreclose the determination of A from also being based on C. In other instances, A may be determined based solely on B.

DETAILED DESCRIPTION

FIG. 1 depicts a flowchart of a first embodiment of a method for multi-user co-scheduling according to the disclosure. The method may be performed by a base station. The base station may be connected to a core network and may perform wireless communications with a plurality of UEs to provide communications coverage for the associated geographical area. The base station may comprise, but not limited to, macro base stations, micro base stations, or pico base stations. In various embodiments, a base station can also be interchangeably referred to as a wireless base station, access point, Node B, evolved Node B (eNodeB or eNB) , etc.. For purposes of illustration, the method is illustrated as being sequential. However, portions of the method may be performed in other orders or in parallel (e.g., simultaneously) . The method may comprise the following blocks.

In S11, the method comprises transmitting a first RS to a UE.

The first RS may be Cell-specific RS (CRS) or Channel State Information RS (CSI-RS) .

In S12, the method comprises receiving a first CSI feedback from the UE as the UE measures the first RS.

The first CSI may comprise at least PMI that indicates a precoding matrix the UE recommends the base station to use in downlink transmission. The precoding matrix is used for mapping layers to antenna ports. The precoding technique can perform appropriate weightings to the antennas based on channel conditions, so as to optimize the spatial distribution properties of the signals. The precoding matrix can reflect the weighting of the antennas. PMI may or may not be based on a codebook.

In addition to PMI, the first CSI may further include Rank Indicator (RI) , Channel Quality Indicator (CQI) , and the like. RI indicates the transmission layers (or ranks) or spatial layers the UE recommends the base station to use in the downlink transmission. CQI indicates the downlink channel quality, and the base station can select the code rate for data transmission based on the CQI. Note that the CQI in the first CSI generally does not consider interference, which is SU-CQI. Since the UE doesn't consider the interferences from other UEs within the same cell during the computation of the CQI contained in the first CSI, the CQI cannot accurately reflect the channel quality under MU-MIMO environment, thus the base station will not base on the CQI included in the first CSI to select code rate for the corresponding data transmission, and the CQI in the first CSI can be omitted.

In S13, the method comprises transmitting initial co-scheduling information and a second RS to the UE.

The initial co-scheduling information may comprise an identifier of at least one co-scheduled object that uses the same time-frequency resource as the UE by SM. The initial co-scheduling information may be derived based on the first CSI. A co-scheduled object may be a particular UE or a group of UEs.

In general, the UEs that have chosen the same PMI may probably have the same or similar channel conditions. For example, locations of different UEs may overlap, so that these UEs may have serious interference with one another and thus are not suitable to be co-scheduled. Thus, when performing the initial co-scheduling for the UE, the base station will not pick the UE (s) that has chosen the same PMI as the co-scheduled object of the UE.

The base station may transmit the initial co-scheduling information and the second RS simultaneously or separately. Since the UE may need to measure the second RS based on the initial co-scheduling information, the base station should transmit the initial co-scheduling information no later than the second RS.

In S14, the method comprises receiving a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information.

The second CSI may comprise an indication of an interference level from at least one co-scheduled object. The indication may comprise initial MU-CQI. The MU-CQI computed by the UE based on the initial co-scheduling information-the initial MU-CQI can reflect the inference from all co-scheduled objects in the initial co-scheduling information.

In a particular embodiment, the indication of the interference level may further comprise refined MU-CQI or delta CQI, the delta CQI being a difference between the initial MU-CQI and the refined MU-CQI. The second CSI may further comprise co-scheduled objects modification recommendation information.

If the initial MU-CQI lies beyond a preset range, the UE may modify the initial co-scheduling information to enable the MU-CQI computed based on the modified co-scheduling information lies within the preset range. How to modify the initial co-scheduling information can be expressed by the co-scheduled objects modification information, and the MU-CQI computed based on the modified co-scheduling information may be referred to as refined MU-CQI.

The co-scheduled objects modification recommendation information may include information recommending removing at least one co-scheduled object, including which to the UE the overall interference level (expressed by MU-CQI) lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which to the UE the overall interference level lies within the preset range and which is not present in the initial co-scheduling information.

That the overall interference level lies beyond the preset range may mean the interference including the objects and the UE is too large, hence they are not suitable to be co-scheduled. In contrary, the overall interference level lying within the preset range may indicate that the objects and UE are suitable to be co-scheduled.

In other embodiments, the indication of the interference level can reflect the interference from different co-scheduled objects respectively, and UE may compare the indication of the interference level of each co-scheduled object with the preset range respectively to obtain co-scheduled objects modification recommendation information.

The preset range may be fixed, or may be determined by the base station or the UE according to actual situations. If the preset range is determined by the base station, then the base station may need to transmit the preset range to the UE before the present block. Typically, the preset range can be expressed by at least a threshold at one end. The threshold may be an absolute threshold, and the corresponding indication of the interference level would be initial MU-CQI or refined MU-CQI. Or, the threshold may be a relative threshold, and the corresponding indication would be delta CQI. The threshold should be transmitted before the present block, while it can be transmitted in any order relative to other blocks. For example, the preset range can be transmitted to the UE during the UE accessing process. The base station may inform the UE of the preset range only when the preset range changes so that the preset range can be updated, while in other times the preset range will not be forwarded.

In S15, the method comprises adjusting the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Particular algorithm for obtaining the refined co-scheduling information can be determined according to practical needs. Typically, when the indication of the interference level comprises initial MU-CQI, the adjustment may comprise at least removing from the initial co-scheduling information the identifier of at least one co-scheduled object that is found in the second CSI, the overall interference level including the at least one co-scheduled object to the UE lying beyond a preset range. If the second CSI also comprises an indication of the overall interference including at least an object not present in the initial co-scheduling information, then the adjustment may further comprise adding the object including which the overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

In other embodiments, the indication of the interference level can reflect the interference from different co-scheduled objects respectively, and the base station may compare the indication of the interference level of each co-scheduled object with the preset range respectively to adjust the initial co-scheduling information.

If the second CSI further comprises co-scheduled objects modification recommendation information, then the base station can accept the UE’s recommendation and adjust the identifiers of the co-scheduled objects in the initial co-scheduling information according to the co-scheduled objects modification recommendation information. Understandably, the base station may choose not to accept the UE’s recommendation, but adjust the initial co-scheduling information at its discretion, for example, when recommendations from different UEs conflict.

The base station can select the code rate for the corresponding data transmission based on the CQI. If the base station accepts the co-scheduled objects modification recommendation of the UE, then it can base on the refined MU-CQI to select the code rate, where the refined MU-CQI may be contained in the second CSI or may be computed based on the initial MU-CQI and delta CQI contained in the second CSI. Otherwise if the base station doesn’ t accept the co-scheduled objects modification recommendation of the UE, then it can directly use the initial MU-CQI contained in the second CSI to select the code rate.

Note, after completion of the present co-scheduling, the next co-scheduling may be restarted for a new cycle, in which blocks S11 through S15 may be performed. Or, the refined co-scheduling information obtained in the present co-scheduling may serve as the initial co-scheduling information of the next co-scheduling, namely, blocks S11 and S12 may be skipped to turn to blocks S13 to S15 directly.

According to the present embodiment, the base station may send twice the RS to the UE. The UE may measure the first RS and feedback first CSI, based on which the base station may perform initial scheduling and transmit the initial scheduling information and a second RS to the UE. The UE may measure the second RS at least based on the initial scheduling information to generate second CSI, and transmit the second CSI to the base station. The base station may then adjust the initial scheduling according to the second CSI to obtain refined co-scheduling information. Compared with the prior art, the UE scheduling is centralized on the base station, avoiding the potential conflicts between decisions different UEs actively make. In addition, the decision-making uses the CSI the UE feeds back after measurement, so the scheduling accuracy is improved, resulting in enhanced system performance.

Referring now to FIG. 2, a flowchart illustrating a second embodiment of a method for multi-user co-scheduling according to the disclosure is depicted, which is based on the first embodiment of the method for multi-user co-scheduling and further comprises the following blocks.

In S16, the method comprises transmitting signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information.

In other embodiments, if the UE actively transmits the co-scheduled objects modification information instead of transmitting it in response to the signaling from the base station, then block S16 can be omitted.

In S17, the method comprises receiving aperiodic co-scheduled objects modification recommendation information from the UE.

Typically, a time interval between the UE’s two adjacent transmissions of the aperiodic co-scheduled objects modification recommendation information may be greater than the period of transmitting the second CSI. In this case, the second CSI typically may not include the co-scheduled objects modification recommendation information, in order to reduce the transmission frequency of the co-scheduled objects modification recommendation information and the uplink signaling overheads.

In S18, the method comprises adjusting the identifiers of the co-scheduled objects in the initial co-scheduling information according to the co-scheduled objects modification recommendation information to obtain refined co-scheduling information.

The base station can accept the recommendation of the UE and adjust the identifiers of the co-scheduled objects in the initial co-scheduling information according to the co-scheduled objects modification recommendation information. In some embodiments, however, the base station may choose not to accept the recommendation, but adjust the initial co-scheduling information at its discretion.

Note, if, by receiving the co-scheduled objects modification recommendation information, the base station has already adjusted the initial co-scheduling information according to the second CSI, then the base station may make further adjustments according to the co-scheduled objects modification recommendation information, or ignore the received co-scheduled objects modification recommendation information.

Referring now to FIG. 3, a flowchart of a third embodiment of a method for multi-user co-scheduling according to the disclosure is depicted, which is based on the first embodiment of the method for multi-user co-scheduling and further comprises the following blocks.

In S19, the method comprises transmitting data based on the refined co-scheduling information or the initial co-scheduling information.

The base station may transmit data based on the refined co-scheduling information in the downlink data transmission of present cycle, or in the downlink data transmission of the next cycle while the downlink data transmission of present cycle may still use the initial co-scheduling information, in which case the refined co-scheduling information would serve as the initial co-scheduling information of the next co-scheduling cycle where the operations of transmitting the first RS and receiving the first CSI may be reduced.

Referring now to FIG. 4, a flowchart illustrating a fourth embodiment of a method for multi-user co-scheduling is depicted, which is based on the first embodiment of the method for multi-user co-scheduling and which is applied to FD-MIMO and in which the first RS is different from the second RS.

FD-MIMO is equipped with two-dimensional antenna array (including a single column of cross-poles) with 8 or more Transceiver Units (TXRUs) per transmission point. A TXRU is only associated with antenna elements with the same polarization, and has its own independent amplitude and phase control.

The present embodiment is a further extension of the first embodiment of the method for multi-user co-scheduling, thus common contents therewith will not detailed again. The method may comprise the following blocks.

In S110, the base station may transmit a preset range to a UE.

The present block S110 as illustrated in FIG. 4 may be executed before block S111. In practice, the present block can be executed at any point before block S117. If the base station has transmitted the preset range to the UE in previous cycle and has yet modified it, then the present block can be omitted.

In S111, the base station may transmit a first RS to a UE.

The first RS may be CRS or CSI-RS. If the first RS is CSI-RS, it may comprise non-precoded CSI-RS or beamformed CSI-RS.

In FD-MIMO, as shown in FIG. 5, the overall beamforming for the downlink data signal includes three stages: W_data＝W_TW_PW_U, where W_data is a mapping matrix used by the beamforming for data signals, W_U is a data precoding mapping matrix used in mapping of data streams to antenna ports, W_Pis a port virtualization matrix used in mapping of antenna ports to TXRUs, and W_T is an TXRU virtualization matrix used in mapping of TXRUs to antenna elements. In the figure N_s is the number of data streams, N_AP is the number of antenna ports, N_U is the number of TXRUs, and N_r is the number of antenna elements, and N_s≤N_AP≤N_U≤N_r.

By contrast, the beamforming for CSI-RS only include the latter two stages: W_CSI-RS＝W_TW_P, where W_CSI-RS is a mapping matrix used in the beamforming for CSI-RS, W_Pis a port virtualization matrix used in mapping from the antenna ports to TXRUs, W_Tis an TXRU virtualization matrix used in mapping from TXRUs to antenna elements. In other words, the data precoding matrix, i.e., W_U, is only for data signals, and is not included in RSs.

Depending on the port virtualization, the CSI-RS can be classified into two categories: non-precoded CSI-RS and beamformed CSI-RS, dubbed as Class A and Class B respectively. The first category may comprise schemes where different CSI-RS ports have the same wide beam width and direction, and hence generally cell wide coverage. Normally, the one-to-one mapping between the ports and TXRU is adopted in the port virtualization. On the other hand, the second category may comprise schemes where (at least at a given time/frequency) CSI-RS ports have narrow beam widths and hence not cell wide coverage. Moreover, at least from the base station perspective, at least some CSI-RS port-resource combinations have different beam directions.

Beamformed CSI-RS configuration can be supported in the following manners:

Class B with multiple CSI-RS resources (K>1) : The beams are distinguished in CSI-RS resource level, the same beam is applied in the same CSI-RS resource, and different beams can be applied in different CSI-RS resources. Note that K refers to the number of configured CSI-RS resources.

Class B with one CSI-RS resource (K＝1) : The beams are distinguished in port level, the same beam is applied in the same group of ports in the configured CSI-RS resource, and different beams can be applied in different groups of ports.

In S112, the UE may measure the first RS to generate first CSI.

The first CSI may comprise at least PMI, i.e., the W_U the UE recommends to use.

In S113, the UE may transmit the first CSI to the base station.

In S114, the base station may determine the initial co-scheduling information and the second RS.

The second RS may be different from the first RS, and the second RS may be generated based on the first CSI. Specifically, the second RS may be beamformed CSI-RS with multiple CSI-RS time-frequency resources. Different time-frequency resources may correspond to different beams, and at least one beam may be formed based on the PMI in the first CSI. In a particular embodiment, the second RS serves as the first RS of the next cycle. In this case, the first RS of the next cycle is omitted, and the initial co-scheduling information of the next cycle is determined based on the second CSI /aperiodic co-scheduled objects modification recommendation information of one or more cycles prior to the next cycle.

Different UEs that have chosen the same PMI may share one beam. If the first RS is CRS or non-precoded CSI-RS, then the W_P used in the corresponding beamforming may be the same as the PMI in the first CSI. If the first RS is beamformed CSI-RS, such as the second RS used in the previous co-scheduling cycle, then the W_P1 used by the first RS may be multiplied with the PMI in the first CSI, and the product may serve as the W_P in the present beamforming. Alternatively, the PMI in the first CSI can be directly taken as the W_P of the present beamforming.

Different UEs that have chosen the same PMI, i.e., those share the same beam, may have serious interference with one another, and thus may not be suitable to be co-scheduled. The base station may perform the initial co-scheduling in the scale of beams but not particular UEs, that is, the co-scheduled objects in the initial co-scheduling information are beams instead of UEs. As this initial scheduling is used for coordinating UEs to perform interference measurement, and UEs using the same beam will cause similar interferences, thus the initial scheduling result in the scale of beams is enough, while it will make this initial scheduling simple to inform, and can improve the flexibility for the later refined scheduling decision.

Because the second RS is beamformed CSI-RS with multiple CSI-RS time-frequency resources and different beams correspond to different time-frequency resources, in the initial co-scheduling information the time-frequency resource parameters can be used to represent the corresponding beams, namely, the identifiers of the co-scheduled objects are the corresponding time-frequency resource parameters of the co-scheduled objects.

The initial co-scheduling information may comprise information of a beam selected for the UE. Likewise, the beam information can also be expressed as the corresponding CSI-RS time-frequency resource parameters.

The initial co-scheduling information may be carried by CSI-RS-Config signaling, and the base station may not transmit CSI-IM-Config signaling to the UE. In this case, the resourceConfig IE (information element) and subframeConfig IE in the CSI-RS-Config signaling may comprise the parameters of the time-frequency resources corresponding to the co-scheduled beam (s) . If the base station selects beams for the UEs, then the CSI-RS-Config signaling may further comprise the parameters of the time-frequency resources corresponding to the selected beam (s) , or the base station can inform the UE of the selected beam information in other ways.

The initial co-scheduling information may also be carried by CSI-IM-Config signaling, and the base station may still need to transmit the CSI-RS-Config signaling. In this case, the resourceConfig IE and subframeConfig IE in the CSI-IM-Config may comprise the parameters of the time-frequency resources corresponding to the co-scheduled beam (s) . The resourceConfig IE and subframeConfig IE in the CSI-RS-Config may comprise only the parameters of the corresponding time-frequency resource parameters of beam (s) of other non-co-scheduled objects. If the base station selects the beams for the UEs, then the beam (s) of the non-co-scheduled objects may comprise the selected beams； or comprise only the corresponding time-frequency resource parameters of the co-scheduled beam (s) ； or comprise time-frequency resource parameters of both the co-scheduled beam (s) and other non-co-scheduled beam (s) . In a particular embodiment, the CSI-RS-Config signaling may comprise the corresponding time-frequency resource parameters of K beams.

Both the CSI-RS-Config and CSI-IM-Config signaling are legacy signaling, which can be used to carry the initial co-scheduling information without introducing new signaling overheads.

In S115, the base station may transmit the initial co-scheduling information and a second RS to the UE.

In S116, the base station may transmit first signaling to the UE.

The first signaling is used to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information. UE may adjust the second CSI according to the first signaling before transmitting the second CSI to the base station. For example, if the base station does not plan to use the refined co-scheduling information for data transmission at the present cycle, the second CSI of the UE may exclude the delta CQI or refined MU-CQI, but just include the initial MU-CQI to reduce signaling overhead.

The present block as illustrated in FIG. 4 may be executed before block S117. In practice, the present block can be executed at any point before block S118. If the base station has transmitted the first signaling to the UE in previous cycle and has yet modified it, then the present block can be omitted.

In S117, the UE may measure the second RS at least based on the second RS to generate second CSI.

First, the UE may measure the channel. If the base station has selected a beam for the UE, then the UE can directly measure the channel in corresponding resource. Regardless of whether the base station has selected a beam for the UE, the UE can measure the channels corresponding to multiple resources (e.g., the resources contained in the CSI-RS-Config signaling) and then select a resource, in which case the second CSI should include the CSI-RS resource index (CRI) indicative of the selected resource. The UE may further determine the RI and select the best PMI based on the channel measurement result.

Next, the UE may compute the initial MU-CQI according to the initial scheduling information. Different from SU-CQI, the calculation of the MU-CQI may require Signal to Interference plus Noise Ratio (SINR) which takes the multi-user interference to intra-cell UEs into consideration. The interference measurement may use just Nonzero Power (NZP) CSI-RS, and the identifiers of the co-scheduled objects, i.e., the corresponding time-frequency resource parameters of the co-scheduled objects may be based on to determine which CSI-RS resource (s) will be measured.

Note, if the UE is able to acquire the information of objects not present in the initial co-scheduling information, for example, when the initial co-scheduling information is carried by the CSI-IM-Config signaling while the CSI-RS-Config signaling comprises the parameters of other non-co-scheduled objects in addition to the selected beams, the UE can compute the interference level from the objects not present in the initial co-scheduling information, and thus make a recommendation of adding object (s) . In order to reduce the signaling overhead and the power consumption for UE measurements, only the UE’s recommendation of removing object (s) may be allowed, while the recommendation of adding object (s) would be prohibited.

In S118, the UE may transmit the second CSI to the base station.

The second CSI may comprise at least an indication of interference. If the UE actively chooses a beam, the second CSI may further comprise CRI. The second CSI may comprise at least one of RI, PMI, and co-scheduled objects modification recommendation information.

To reduce the signaling overhead, the UE can remove once from the second CSI the duplicate part of the parameters (e.g. RI, PMI) corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI. If the CRI is the same as the corresponding resource parameters of the beam the base station selects for the UE, then the UE can remove the CRI from the second CSI. Further, the UE can choose not to include the co-scheduled objects modification recommendation information in the second CSI, but report the co-scheduled objects modification recommendation information aperiodically.

In S119, the base station may determine the refined co-scheduling information.

The base station may adjust the initial co-scheduling information according to the second CSI to obtain the refined co-scheduling information.

For example, referring to FIG. 6, the base station may transmit non-precoded CSI-RS, i.e., the first RS, to a total of five UEs within its communication coverage, including UE A, UE B, UE C, UE D, and UE E. Each UE may measure the non-precoded CSI-RS to obtain their respective first CSI.

The base station may then group the UEs based on the first CSI fed back from each UE, the grouping results are shown in FIG. 7, in which the UEs within a solid frame are scheduled to a same group and share one beam. In particular, the base station divides UEs A and B that have chosen the same PMI into a first group, which share beam 1； UEs C and D choosing the same PMI into a second group, which share beam 2； and UE E choosing different PMI from the other UEs solely into a third group, which uses beam 3.

The base station may take each of the beam 1, beam 2, and beam 3 as the initial co-scheduled object of the other two, i.e., all the beams may be co-scheduled to generate the initial co-scheduling information. The initial co-scheduling information and a second RS generated based on the grouping results may be transmitted to the UEs. Each UE may measure the second RS based on the initial co-scheduling information to obtain their respective second CSI.

UEs A and C may respectively detect that the interference level from beam 3 lies beyond the preset range, and thus recommend removing beam 3 in their respective second CSI, whereas UEs B and D don’t make such a recommendation. The base station may adjust the initial co-scheduling information according to the second CSI the UEs feeds back to obtain the refined co-scheduling information. Specifically, UEs A and C are co-scheduled, UEs B, D, and E are co-scheduled. As shown in FIG. 8, the UEs within a dashed frame are co-scheduled, and the beam used by each UE remains unchanged. Note in FIGs. 6 through 8 the location of each UE is only illustrative and does not represent the actual location of the UE.

The following describes the simulations and corresponding simulation results for the fourth embodiment of the method for multi-user co-scheduling, in which the base station is referred to as eNodeB, abbreviated eNB.

The 3d channel model based on 3GPP TR 36.873 is used, and the parameters are shown in following Table 1.

Network structure	Hexagon cells with single ring
3d channel model	3GPP 3D-Uma (cf. TR 36.873)
Inter-site distance	500 m
#sectors per site	3
#UEs served in each sector	20
eNB height	25 m
#eNB transmit antenna ports	16
#UE antenna ports	1
Trace length	1000 ms
TTI length
	1 ms
Simulation duration length	200 TTIs
channel feedback delay	6 TTIs
SINR threshold	6 dB
UE speed	5 km/h
eNB transmit power	43 dBm
Number of PRBs	100
Bandwidth of each RB	180 kHz
Noise power spectral density	-174 dBm/Hz
UE noise figure	6 dB
Codebook configuration	N1 ＝ 4, N2 ＝ 2, O1 ＝ 4, O2 ＝ 4
Traffic model	Full buffer

Table 1: simulation parameters

To demonstrate the advantage of using adaptive scheduling with UEs’ recommendation, we use the conventional method in which the eNB make the scheduling decision as the baseline method.

We first compare the average throughput of the proposed method against the baseline method, as shown in FIG. 9. The cases where the maximum MU size equaling 1, 2, 3, and 4 are simulated. When MU ＝ 1, the proposed method will degrade to the baseline method. The simulation results demonstrate that the proposed method can achieve around 10％throughput gain upon the baseline for MU >1.

Next, we compare the ratios of UEs with high MU interference. The UE with high MU interference refers to the UE for which the difference between SU-CQI and MU-CQI exceeds a predefined threshold (i.e., cannot achieve the desired MU-MIMO performance gain) . In the proposed method, such UEs will provide recommendation to eNB, based on which eNB can refine the scheduling, while in the baseline method, such UEs do not take any action. The simulation results are shown in FIG. 10.

The simulation results can demonstrate that the proposed method can greatly reduce the ratio of UEs with high MU interference. The ratio of high MU interference UEs increases with the MU size. The increasing of ratio of high MU interference UEs will saturate with the MU size.

Next, we illustrate the ratio of different group sizes in the scheduling results for both the proposed method and the baseline method, as shown in FIG. 11-13. Here the group means the set of UEs occupying the same resources and form MU transmissions. Each group size cannot exceed the preset maximum MU size.

The simulation results can demonstrate that not all UEs can achieve the maximum MU size, since large size is more likely to cause large MU interference. The baseline method tends to make larger group size, while such grouping is highly probable to cause large MU interference. The proposed method adopting UEs’ recommendation can effectively avoid such blind grouping, and compared with the baseline method, fewer UEs can achieve the preset MU size.

FIG. 14 depicts a flowchart illustrating a fifth embodiment of a method for multi-user co-scheduling according to the disclosure. The method may be performed by a User Equipment (UE) . The UE can be stationary or mobile, including, but not limited to, cellular phones, personal digital assistants (PDA) , wireless modems, tablet computers, notebook computers, cordless phones, and so forth. The method may comprise the following blocks.

In S21, the UE may measure a first RS from the base station to generate first CSI.

The first RS may be CRS or CSI-RS. The first CSI may comprise at least PMI that indicates a precoding matrix the UE recommends the base station to use in the downlink transmission. The precoding matrix is used for mapping layers to antenna ports. The precoding technique can perform appropriate weightings to the antennas based on channel conditions, in order to optimize the spatial distribution properties of signals. The precoding matrix can reflect the weighting of the antennas. PMI may or may not be based on a codebook. In addition to PMI, the first CSI may further include Rank Indicator (RI) , Channel Quality Indicator (CQI) , and the like. RI indicates the transmission layers (or ranks) the UE recommends the base station to use in the downlink transmission, i.e., recommendation on the spatial layers to be used in the downlink joint transmission. CQI indicates the downlink channel quality, and the base station can select the code rate for data transmission based on the CQI. Note the CQI in the first CSI generally does not considered interference, which is Single User-Channel Quality Indicator (SU-CQI) . Since the UE doesn't consider the interferences from other UEs within the same cell during the computation of the CQI contained in the first CSI, the CQI cannot accurately reflect the channel quality under MU-MIMO environment, thus the base station will not base on the CQI included in the first CSI to select code rate for the corresponding data transmission, and the CQI in the first CSI can be omitted.

In S22, the UE may transmit the first CSI to the base station.

In S23, the UE may receive initial co-scheduling information from the base station.

The initial co-scheduling information may comprise an identifier of at least one co-scheduled object that uses the same time-frequency resource as the UE by SM. The initial co-scheduling information may be derived based on the first CSI. Each co-scheduled object may be a particular UE or a group of UEs.

In S24, the UE may measure a second RS from the base station at least based on the initial co-scheduling information to generate second CSI.

The initial co-scheduling information and the second RS may be transmitted simultaneously or separately. The initial co-scheduling information should be transmitted no later than the second RS.

The co-scheduled objects modification recommendation information may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE (expressed by MU-CQI) lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information. If the UE can obtain through measurement the interference level from an object not present in the initial co-scheduling information, it can put forward a proposal to add an object. To further reduce the signaling overheads and the power consumption for UE measurements, the UE can be prohibited from making recommendations of adding object (s) .

That the overall interference level lies beyond the preset range may mean the interference between the objects and the UE is too large, hence they are not suitable for being co-scheduled. In contrary, the interference level lying within the preset range may indicate that the objects and the UE are suitable to be co-scheduled.

The preset range may be fixed, or may be determined by the base station or the UE according to actual conditions. If the preset range is determined by the base station, then the UE may need to receive the preset range from the base station before the present block. Typically, the preset range may be expressed by at least a threshold at one end. The threshold can be an absolute threshold, and the corresponding interference indication would be initial MU-CQI or refined MU-CQI. Or, the threshold may be a relative threshold, and the corresponding interference indication would be delta CQI.

In S25, the UE may transmit the second CSI to the base station.

As such, the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information. The particular algorithm for obtaining the refined co-scheduling information can be determined according to practical needs. Typically, when the indication of the interference level comprises initial MU-CQI, the adjustment may comprise at least removing from the initial co-scheduling information the identifier of at least one initial co-scheduled object that is found in the second CSI, the overall interference level including the at least one initial co-scheduled object to the UE lying beyond a preset range, so as to obtain the refined co-scheduling information. If the UE detects the overall interference level including at least an object not present in the initial co-scheduling information, then the adjustment may further comprise adding the object, including which the level of overall interference lies within the preset range and which is not present in the initial co-scheduling information.

If the second CSI further comprises co-scheduled objects modification recommendation information, then the base station can accept the UE’s recommendation and adjust the identifiers of the co-scheduled objects in the initial co-scheduling information according to the co-scheduled objects modification recommendation information. The base station of course may choose not to accept the recommendation of the UE, but adjust the initial co-scheduling information at its discretion.

According to the present embodiment, the base station may send twice the RS to the UE. The UE may measure a first RS and feedback first CSI, based on which the base station may perform initial scheduling and transmit the initial scheduling information as well as a second RS to the UE. The UE may measure the second RS at least based on the initial scheduling information to generate second CSI, and transmit the second CSI to the base station. The base station may thus adjust the initial scheduling according to the second CSI to obtain refined co-scheduling information. Compared with the prior art, the UE scheduling is centralized on the base station, thus avoiding the potential conflicts when the UEs make decisions on their own. In addition, the decision-making process uses the CSI feedback from the UE, so the scheduling accuracy is improved, resulting in enhanced system performance.

Referring now to FIG. 15, a flowchart of a sixth embodiment of a method for multi-user co-scheduling according to the disclosure is depicted, which is based on the fifth embodiment of the method for multi-user co-scheduling and further comprises the following blocks.

In S26, the method comprises receiving from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information.

In other embodiments, if the UE actively transmits the co-scheduled objects modification information instead of transmitting it in response to the signaling from the base station, then block S26 can be omitted.

In S27, the method comprises transmitting aperiodic co-scheduled objects modification recommendation information to the base station.

The co-scheduled objects modification recommendation information may include information recommending removing at least one co-scheduled object, from which the level of interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, from which the level of interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Typically, the time interval between the UE’s two adjacent transmissions of the aperiodic co-scheduled objects modification recommendation information may be greater than the period of transmitting the second CSI. In this case, the second CSI typically may not include the co-scheduled objects modification recommendation information, so as to reduce the transmission frequency of the co-scheduled objects modification recommendation information and the uplink signaling overheads.

When the fifth embodiment of the method for multi-user co-scheduling is applied to FD-MIMO and the first RS is different from the second RS, see relevant description of the fourth embodiment of the method for multi-user co-scheduling.

Referring now to FIG. 16, a block diagram of a first embodiment of a base station is depicted. The base station may comprise a first transmitting module 11, a first receiving module 12, a second transmitting module 13, a second receiving module 14, and an adjustment module 15.

The first transmitting module 11 may be configured to transmit a first RS to a UE.

The first receiving module 12 may be configured to receive a first CSI feedback from the UE as the UE measures the first RS.

The second transmitting module 13 may be configured to transmit initial co-scheduling information and a second RS to the UE. The initial co-scheduling information may comprise an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission. The initial co-scheduling information may be derived based on the first CSI.

The second receiving module 14 may be configured to receive a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information. The second CSI may comprise an indication of an interference level from at least one co-scheduled object.

The adjustment module 15 may be configured to adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Specifically, the adjustment module 15 may be configured to remove from the initial co-scheduling information the identifier of at least one initial co-scheduled object that is found in the second CSI, the overall interference level including the at least one initial co-scheduled object to the UE lying beyond a preset range.

Specifically, the adjustment module 15 may be configured to add to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Specifically, the indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information. The adjustment module may be configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.

Specifically, the second RS may be different from the first RS. The second RS may be carried by at least two beams formed through beamforming, where a port virtualization matrix among the mapping matrices used by the beamforming for at least one beam may be the same as the PMI in the first CSI.

Specifically, each co-scheduled object may be a beam. Different beams may correspond to different time-frequency resources.

Specifically, the identifier of each co-scheduled object may comprise parameters of time-frequency resource corresponding to the co-scheduled object.

Referring now to FIG. 17, a block diagram of a second embodiment of a base station is depicted. The base station may comprise a processor 110 and a transceiver 120 coupled to processor 110 via a bus.

The transceiver 120 may be configured to transmit and receive data, and serve as an interface through which the base station communicates with other communication equipment.

Processor 110 may control operations of the base station, and may also be referred to as a Central Processing Unit (CPU) . Processor 110 may be an integrated circuit chip with signal processing capabilities, such as a general purpose processor, Digital Signal Processor (DSP) , Application Specific Integrated Circuit (ASIC) , Field Programmable Gate Array (FPGA) , or any other programmable logic devices, discrete gates, transistor logic devices, or discrete hardware components. The general purpose processor may be a microprocessor or any conventional processor.

The base station may further comprise a memory (not shown) used to store the commands and data necessary for operations of the processor 110. The memory can also store the data received by the transceiver 120.

Processor 110 may be configured to: transmit via the transceiver 120 a first RS to a UE； receive via the transceiver 120 a first CSI feedback from the UE as the UE measures the first RS； transmit via the transceiver 120 initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； receive via the transceiver 120 a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Specifically, processor 110 may be configured to remove from the initial co-scheduling information the identifier of at least one initial co-scheduled object that is found in the second CSI, the overall interference level including the at least one initial co-scheduled object to the UE lying beyond a preset range.

Specifically, processor 110 may be configured to add to the initial co-scheduling information the identifier of at least one initial co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Specifically, the indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) .

Specifically, the indication of the interference level may further comprise refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information. The processor110 may be configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.

Specifically, processor 110 may further be configured to receive via the transceiver 120 aperiodic initial co-scheduling object adjustment recommendation information from the UE； and add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the initial co-scheduling object adjustment recommendation information to obtain refined co-scheduling information.

Specifically, processor 110 may further be configured to transmit via the transceiver 120 signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information before receiving via the transceiver 120 the aperiodic co-scheduled objects modification recommendation information.

Specifically, processor 110 may further be configured to transmit data based on the refined co-scheduling information or the initial co-scheduling information, wherein in the case the data is transmitted based on the initial co-scheduling information, the refined co-scheduling information is used for the data transmission of the next cycle.

Specifically, processor 110 may further be configured to transmit via the transceiver 120 signaling to the UE to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information.

Specifically, processor 110 may further be configured to transmit via the transceiver120 a preset range to the UE, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

Specifically, the second RS may be different from the first RS, and the second RS may be generated based on the first RS.

Specifically, the second RS may be carried by at least two beams formed through beamforming, where a port virtualization matrix among the mapping matrices used by the beamforming for at least one beam may be the same as the PMI in the first CSI.

Specifically, the second RS may serve as the first RS of the next cycle, and/or the first RS may be the first RS or second RS of the previous cycle.

Specifically, the initial co-scheduling information may further comprise information of a beam selected for the UE； and/or the second CSI may comprise information of a beam the UE actively selects.

Specifically, each co-scheduled object may be a beam.

Specifically, different beams may correspond to different time-frequency resources.

Specifically, the initial co-scheduling information may be carried by CSI-RS-Config or CSI-IM-Config signaling.

For functions of various components or modules of the base station according to the present embodiment, one may refer to the relevant description of corresponding method embodiment, thus they will not be detailed again.

Referring now to FIG. 18, a first embodiment of a UE according to the disclosure is depicted. The UE may comprise a first measurement module 21, a first transmitting module 22, a first receiving module 23, a second measurement module 24, and a second transmitting module 25.

The first measurement module may be configured to measure a first RS from a base station to generate first CSI.

The first transmitting module 22 may be configured to transmit the first CSI to the base station.

The first receiving module 23 may be configured to receive initial co-scheduling information from the base station. The initial co-scheduling information may comprise an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission. The initial co-scheduling information may be derived based on the first CSI.

The second measurement module 24 may be configured to measure a second RS from the base station at least based on the initial co-scheduling information to generate second CSI. The second CSI may comprise an indication of an interference level from at least one co-scheduled object.

The second transmitting module 25 may be configured to transmit second CSI to the base station, so that the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Specifically, the indication of the interference level may comprise initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Specifically, the second transmitting module may be configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit the reduced second CSI to the base station.

Referring now to FIG. 19, a block diagram of a second embodiment of a UE according to the disclosure is depicted, which is based on the first embodiment of the UE and further comprises a third transmitting module 26 configured to transmit aperiodic co-scheduled objects modification recommendation information to the base station.

The co-scheduled objects modification recommendation information may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Referring now to FIG. 20, a block diagram of a third embodiment of a UE according to the disclosure is depicted. The UE may comprise a processor 210 and a communication circuit 220 coupled to the processor 210 via a bus.

The communication circuit 220 may be configured to transmit and receive data, and serve as an interface through which the UE communicates with other communication equipment.

Processor 210 may control operations of the UE, and can also be referred to as a CPU. Processor 210 may be an integrated circuit chip with signal processing capabilities. Processor 210 may also be a general purpose processor, DSP, ASIC, FPGA, or other programmable logic devices, discrete gates, transistor logic devices, discrete hardware components. The general purpose processor may be a microprocessor or any conventional processor.

The UE may further include a memory (not shown) used to store the commands and data necessary for operations of the processor 210. The memory can also store the data received by the communication circuit 220.

Processor 210 may be configured to: measure via the communication circuit 220 a first RS from a base station to generate first CSI； transmit via the communication circuit 220 the first CSI to the base station； receive via the communication circuit 220 initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； measure via the communication circuit 220 a second RS from the base station to generate a second CSI at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and transmit via the communication circuit 220 the second CSI to the base station, so that the base station may adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.

Specifically, the indication of the interference level may comprise initial MU-CQI.

Specifically, the indication of the interference level may further comprise refined MU-CQI or delta CQI. The second CSI may further comprise co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Specifically, processor 210may be configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit via the communication circuit 220 the reduced second CSI to the base station.

Specifically, processor 210 may be configured to transmit to the base station via the communication circuit 220aperiodic co-scheduled objects modification recommendation information, which may include information recommending removing at least one co-scheduled object, including which the level of overall interference to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the level of overall interference to the UE lies within the preset range and which is not present in the initial co-scheduling information.

Specifically, processor 210 may further be configured to receive via the communication circuit 220 from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information before transmit to the base station via the communication circuit 220 aperiodic co-scheduled objects modification recommendation information.

Specifically, processor 210 may further be configured to receive via the communication circuit 220 the preset range from the base station, wherein the preset range may be expressed by at least a threshold at one end, the threshold may be an absolute threshold or a relative threshold.

Specifically, processor 210 may further be configured to receive via the communication circuit 220 from the base station signaling that informs the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information； and adjust the second CSI based on the signaling before transmitting via the communication circuit 220 the second CSI to the base station.

Specifically, the second RS may be carried by at least two beams formed through beamforming. The initial co-scheduling information may comprise information of a beam selected for the UE. The second CSI may comprise information of a beam the UE actively selects.

For functions of various components or modules of the UE according to the present embodiment, one may refer to the relevant description of corresponding method embodiment, thus they will not be detailed again.

It will be appreciated that the disclosed base stations, UEs, and methods may also be implemented in other forms. Rather, the base stations and UEs as described are merely illustrative, for example, the division of modules or units is based solely on logic functions, thus in actual implementations there may be other division methods, e.g., multiple units or components may be combined or integrated onto another system, or some features may be ignored or not executed. In addition, mutual couplings, direct couplings, or communication connections as displayed or discussed may be achieved through some interfaces, devices, or units, and may be achieved electrically, mechanically, or in other forms.

Separated units as described may or may not be physically separated. Components displayed as units may or may not be physical units, and may reside at one location or may be distributed to multiple networked units. Part or all of the units may be selectively adopted according to actual requirements to achieve objectives of the disclosure.

Additionally, various functional units discussed in the disclosure may be integrated into one processing unit, or may be presented as various physically separated units, and two or more units may be integrated into one. The integrated units may be implemented by hardware or as software functional units.

If the integrated units are implemented as software functional units and sold or used as standalone products, they may be stored in a computer readable storage medium. On the basis of such an understanding, the substantial technical solution or all or part of the technical solution of the disclosure may be embodied as software products. Computer software products can be stored in a storage medium and can include multiple instructions enabling a computing device (e.g., a personal computer, a server, a network device, etc. ) or a processor to execute all or part of the methods as described in the disclosure. The storage medium may include all kinds of media that can store program codes, such as a USB flash disk, mobile hard drive, Read-Only Memory (ROM) , Random Access Memory (RAM) , magnetic disk, or optical disk.

The above description merely depicts some exemplary embodiments of the disclosure, but is not meant to limit the scope of the disclosure. Any equivalent structure or flow transformations made to the disclosure, or any direct or indirect applications of the disclosure on other related fields, shall all be covered within the protection of the disclosure.

Claims

A method for multi-user co-scheduling, comprising:

transmitting a first RS to a UE；

receiving a first Channel State information (CSI) feedback from the UE as the UE measures the first RS；

transmitting initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by Spatial Multiplexing (SM) in the data transmission, the initial co-scheduling information being derived based on the first CSI；

receiving a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and

adjusting the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The method according to claim 1, wherein adjusting the initial co-scheduling information according to the second CSI comprises:

removing from the initial co-scheduling information the identifier of at least one co-scheduled object that is found in the second CSI, the overall interference level including the at least one co-scheduled object to the UE lying beyond a preset range.
The method according to claim 2, wherein adjusting the initial co-scheduling information according to the second CSI further comprises:

adding to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The method according to claim 1, wherein the indication of the interference level comprises initial Multi-User Channel Quality Indicator (MU-CQI) .
The method according to claim 4, wherein the indication of the interference level further comprises refined MU-CQI or delta CQI, and the second CSI further comprises co-scheduled objects modification recommendation information； and

adjusting the initial co-scheduling information according to the second CSI comprises:

adding or removing the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.
The method according to claim 1, further comprising:

receiving aperiodic co-scheduled objects modification recommendation information from the UE； and

adding or removing the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information to obtain refined co-scheduling information.
The method according to claim 6, further comprising, before receiving the aperiodic co-scheduled objects modification recommendation information:

transmitting signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information.
The method according to any one of claims 1-7, further comprising:

transmitting data based on the refined co-scheduling information or the initial co-scheduling information, wherein in the case the data is transmitted based on the initial co-scheduling information, the refined co-scheduling information is used for the data transmission of the next cycle.
The method according to claim 8, further comprising:

transmitting signaling to the UE to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information.
The method according to any one of claims 1-7, further comprising:

transmitting a preset range to the UE, wherein the preset range is expressed by at least a threshold at one end, the threshold is an absolute threshold or a relative threshold.
The method according to any one of claims 1-7, wherein the second RS is different from the first RS, and the second RS is generated based on the first RS.
The method according to claim 11, wherein the second RS is carried by at least two beams formed through beamforming, wherein a port virtualization matrix among mapping matrices used by the beamforming for at least one beam is the same as Precoding Matrix Information (PMI) in the first CSI.
The method according to claim 12, wherein the second RS serves as the second RS of the next cycle, wherein the first RS of the next cycle is omitted, and the initial co-scheduling information of the next cycle is determined based on the second CSI /aperiodic co-scheduled objects modification recommendation information of one or more cycles prior to the next cycle.
The method according to claim 12, wherein the initial co-scheduling information further comprise information of a beam selected for the UE； and/or the second CSI comprises information of a beam the UE actively selects.
The method according to claim 12, wherein each co-scheduled object is a beam.
The method according to claim 15, wherein different beams correspond to different time-frequency resources.
The method according to claim 16, wherein the identifier of each co-scheduled object comprise parameters of time-frequency resource corresponding to the co-scheduled object.
The method according to claim 17, wherein the initial co-scheduling information is carried by CSI-RS-Config or CSI-IM-Config signaling.
A method for multi-user co-scheduling, comprising:

measuring, by a UE, a first RS from a base station to generate first CSI；

transmitting, by the UE, the first CSI to the base station；

receiving, by the UE, initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI；

measuring, by the UE, a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and

transmitting, by the UE, the second CSI to the base station, so that the base station adjusts the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The method according to claim 19, wherein the indication of the interference level comprises initial MU-CQI.
The method according to claim 20, wherein the indication of the interference level further comprises refined MU-CQI or delta CQI, and the second CSI further comprises co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The method according to claim 21, wherein transmitting the second CSI to the base station comprises:

removing once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmitting the reduced second CSI to the base station.
The method according to claim 19, further comprising:

transmitting to the base station aperiodic co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The method according to claim 23, further comprising, before transmitting the aperiodic co-scheduled objects modification recommendation information:

receiving from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information.
The method according to any one of claims 21-24, further comprising:

receiving the preset range from the base station, wherein the preset range is expressed by at least a threshold at one end, the threshold is an absolute threshold or a relative threshold.
The method according to any one of claims 19-24, further comprising, before transmitting the second CSI to the base station:

receiving from the base station signaling that informs the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information；

adjusting the second CSI based on the signaling.
The method according to any one of claims 19-24, wherein the initial co-scheduling information is carried by CSI-RS-Config or CSI-IM-Config signaling.
The method according to any one of claims 19-24, wherein the second RS is carried by at least two beams formed through beamforming, the initial co-scheduling information further comprises information of a beam selected for the UE, and the second CSI further comprises information of a beam the UE actively selects.
A base station, comprising:

a first transmitting module configured to transmit a first RS to a UE；

a first receiving module configured to receive a first CSI feedback from the UE as the UE measures the first RS；

a second transmitting module configured to transmit initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI；

a second receiving module configured to receive a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and

an adjustment module configured to adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The base station according to claim 29, wherein the adjustment module is configured to remove from the initial co-scheduling information the identifier of at least one initial co-scheduled object that is found in the second CSI, the overall interference level including the at least one initial co-scheduled object to the UE lying beyond a preset range.
The base station according to claim 30, wherein the adjustment module is further configured to add to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the overall interference level to the UE lies within the present range and which is not present in the initial co-scheduling information.
The base station according to claim 29, wherein the indication of the interference level comprises initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI, the second CSI further comprises co-scheduled objects modification recommendation information； and

the adjustment module is configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.
The base station equipment according to any one of claims 29-32, wherein the second RS is different from the first RS, the second RS is carried by at least two beams formed through beamforming, and a port virtualization matrix among mapping matrices used by the beamforming for at least one beam is same as PMI in the first CSI.
A User Equipment (UE) , comprising:

a first measurement module configured to measure a first RS from a base station to generate first CSI；

a first transmitting module configured to transmit the first CSI to the base station；

a first receiving module configured to receive initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI；

a second measurement module configured to measure a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and

a second transmitting module configured to transmit the second CSI to the base station, so that the base station adjusts the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The UE according to claim 34, wherein the indication of the interference level comprises initial Multi-User Channel Quality Indicator (MU-CQI) together with refined MU-CQI or delta CQI, the second CSI further comprises co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The UE according to claim 34, wherein the second transmitting module is configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit the reduced second CSI to the base station.
The UE according to claim 34, further comprising:

a third transmitting module configured to transmit to the base station aperiodic co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
A base station comprising a processor and a transceiver coupled to the processor, the processor being configured to:

transmit via the transceiver a first RS to a UE； receive via the transceiver a first CSI feedback from the UE as the UE measures the first RS； transmit via the transceiver initial co-scheduling information and a second RS to the UE, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, the initial co-scheduling information being derived based on the first CSI； receive via the transceiver a second CSI feedback from the UE as the UE measures the second RS at least based on the initial co-scheduling information, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and adjust the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The base station according to claim 38, wherein the processor is configured to remove from the initial co-scheduling information the identifier of at least one co-scheduled object that is found in the second CSI, the overall interference level including the at least one co-scheduled object to the UE lying beyond a preset range.
The base station according to claim 39, wherein the processor is further configured to add to the initial co-scheduling information the identifier of at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The base station according to claim 38, wherein the indication of the interference level comprises initial Multi-User Channel Quality Indicator (MU-CQI) .
The base station according to claim 41, wherein the indication of the interference level further comprises refined MU-CQI or delta CQI, and the second CSI further comprises co-scheduled objects modification recommendation information； and

the processor is configured to add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the co-scheduled objects modification recommendation information.
The base station according to claim 38, wherein the processor is further configured to receive via the transceiver aperiodic co-scheduling object adjustment recommendation information from the UE, and add or remove the identifiers of the co-scheduled objects to or from the initial co-scheduling information according to the initial co-scheduling object adjustment recommendation information to obtain refined co-scheduling information.
The base station according to claim 43, wherein the processor is further configured to transitive the transceiver signaling to the UE to signal the UE to report the aperiodic co-scheduled objects modification recommendation information before receiving via the transceiver the aperiodic co-scheduled objects modification recommendation information.
The base station according to any one of claims 38-44, wherein the processor is further configured to transmit data based on the refined co-scheduling information or the initial co-scheduling information, wherein in the case the data is transmitted based on the initial co-scheduling information, the refined co-scheduling information is used for the data transmission of the next cycle.
The base station according to claim 45, wherein the processor is further configured to transmit via the transceiver signaling to the UE to inform the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information.
The base station according to any one of claims 38-44, wherein the processor is further configured to transmit via the transceiver a preset range to the UE, wherein the preset range is expressed by at least a threshold at one end, the threshold is an absolute threshold or a relative threshold.
The base station according to any one of claims 38-44, wherein the second RS is different from the first RS, and the second RS is generated based on the first RS.
The base station according to claim 48, wherein the second RS is carried by at least two beams formed through beamforming, wherein a port virtualization matrix among mapping matrices used by the beamforming for at least one beam is the same as PMI in the first CSI.
The base station according to claim 49, wherein the second RS serves as the second RS of the next cycle, wherein the first RS of the next cycle is omitted, and the initial co-scheduling information of the next cycle is determined based on the second CSI /aperiodic co-scheduled objects modification recommendation information of one or more cycles prior to the next cycle.
The base station according to claim 49, wherein the initial co-scheduling information further comprises information of a beam selected for the UE； and/or the second CSI comprises information of a beam the UE actively selects.
The base station according to claim 49, wherein each co-scheduled object is a beam.
The base station according to claim 52, wherein different beams correspond to different time-frequency resources.
The base station according to claim 53, wherein the identifier of each co-scheduled object comprise parameters of time-frequency resource corresponding to the co-scheduled object.
The base station according to claim 54, wherein the initial co-scheduling information is carried by CSI-RS-Config or CSI-IM-Config signaling.
A User Equipment (UE) comprising a processor and a communication circuit coupled to the processor, the processor being configured to:

measure via the communication circuit a first RS from a base station to generate first CSI； transmit via the communication circuit the first CSI to the base station； receive via the communication circuit initial co-scheduling information from the base station, the initial co-scheduling information comprising an identifier of at least one co-scheduled object that is to use the same time-frequency resource as the UE by SM in the data transmission, and the initial co-scheduling information being derived based on the first CSI； measure via the communication circuit a second RS from the base station at least based on the initial co-scheduling information to generate second CSI, the second CSI comprising an indication of an interference level from at least one co-scheduled object； and transmit via the communication circuit the second CSI to the base station, so that the base station adjusts the initial co-scheduling information according to the second CSI to obtain refined co-scheduling information.
The UE according to claim 56, wherein the indication of the interference level comprises initial MU-CQI.
The UE according to claim 57, wherein the indication of the interference level further comprises refined MU-CQI or delta CQI, and the second CSI further comprises co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The UE according to claim 58, wherein the processor is configured to remove once from the second CSI the duplicate part of the parameters corresponding to the initial MU-CQI and those corresponding to the refined MU-CQI and transmit via the communication circuit the reduced second CSI to the base station.
The UE according to claim 56, wherein the processor is further configured to transmit to the base station via the communication circuit aperiodic co-scheduled objects modification recommendation information, which comprises information recommending removing at least one co-scheduled object, including which the overall interference level to the UE lies beyond a preset range, and/or information recommending adding at least one co-scheduled object, including which the overall interference level to the UE lies within the preset range and which is not present in the initial co-scheduling information.
The UE according to claim 60, wherein the processor is further configured to receive via the communication circuit from the base station signaling that signals the UE to report the aperiodic co-scheduled objects modification recommendation information before transmit to the base station via the communication circuit aperiodic co-scheduled objects modification recommendation information.
The UE according to any one of claims58-61, wherein the processor is further configured to receive via the communication circuit the preset range from the base station, wherein the preset range is expressed by at least a threshold at one end, the threshold is an absolute threshold or a relative threshold.
The UE according to any one of claims56-61, wherein the processor is further configured to receive via the communication circuit from the base station signaling that informs the UE that whether the data transmission at the present cycle uses the refined co-scheduling information or the initial co-scheduling information； and adjust the second CSI based on the signaling before transmitting via the communication circuit the second CSI to the base station.
The UE according to any one of claims 56-61, wherein the initial co-scheduling information is carried by CSI-RS-Config or CSI-IM-Config signaling.
The UE according to any one of claims 56-61, wherein the second RS is carried by at least two beams formed through beamforming, the initial co-scheduling information further comprises information of a beam selected for the UE, and the second CSI further comprises information of a beam the UE actively selects.