Configuration of downlink multi-user multiple-input multiple-output reception for co-scheduled user equipments

Abstract

The present disclosure relates to a technique for enhancing downlink (DL) multi-user multiple-input multiple-output (MU-MIMO) reception for co-scheduled UEs by performing inter-user inference cancellation based on appropriately generated downlink control information (DCI). More specifically, in response to UE-related information indicating that a target UE is configured with other co-scheduled UEs for DL MU-MIMO reception, DCI is generated by a network node and transmitted to the target UE. The DCI indicates at least one group of co-scheduled UEs served by the network node for DL MU-MIMO reception, and also indicates a modulation scheme and / or a demodulation reference signal (DMRS) initialization value for each group of co-scheduled UEs of the at least one group of co-scheduled UEs. By using the DCI, the target UE may efficiently implement DL MU-MIMO reception with the co-scheduled UE.

Description

Technical Field

[0001] This disclosure generally relates to the field of wireless communications. In particular, this disclosure relates to techniques for configuring downlink (DL) multiple-user multiple-input multiple-output (MU-MIMO) reception for user equipment (UE) that is co-scheduled in a wireless communication network. Background Technology

[0002] MIMO has been extensively studied over the past two decades because it can provide spatial multiplexing gain, diversity gain, and interference reduction capabilities. Initially, single-user MIMO (SU-MIMO) was mainly studied to improve system performance. In recent years, for further improvement, the focus has shifted to more practical multi-user MIMO (MU-MIMO) systems, where a base station (BS) or gNB typically serves multiple user units (UEs) simultaneously.

[0003] Compared to SU-MIMO scenarios, MU-MIMO scenarios involve serving more than one UE using the same resource block (RB). However, this does not mean that more UEs on the same RB are always better. Due to spatial correlation and power constraints, if all UEs are scheduled in the same group, they can have a low signal-to-interference-plus-noise ratio (SINR). To address the scheduling problem and reduce computational complexity, UE grouping can be used. Based on this grouping, all UEs are divided into different groups (e.g., based on their spatial correlation) to improve overall performance. After grouping, UE groups are served using different RBs. In this way, the number of UEs served by the same RB can be reduced, and UE performance can be improved.

[0004] In MU-MIMO scenarios, because a single BS or gNB uses the same RB to communicate with many UEs simultaneously, the signal received by each UE suffers from interference designed to target signals from other UEs served by the same BS or gNB. This interference is called inter-user interference (IPI). To eliminate or mitigate IPI, different interference cancellation schemes are applied at the receivers included in each UE. For proper IPI cancellation, the receiver needs to know basic information about the interfering MIMO layer associated with all co-scheduled UEs (i.e., UEs from one or more groups). Providing such information via network signaling based on Auxiliary Downlink Control Information (DCI) has been proposed. However, in this case, another problem arises related to the agreed signaling scheme in terms of network scheduling flexibility. More specifically, such a signaling scheme would constrain co-scheduled UEs to use a certain modulation order, such as Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (16-QAM), etc. Furthermore, there is currently no signaling that informs the target UE of the number of co-scheduled UEs (i.e., the group of UEs). All of these factors lead to reduced network scheduling flexibility. Summary of the Invention

[0005] This summary is provided to present a simplified version of the selection of concepts further described below in the detailed description. This summary is not intended to identify key features of this disclosure, nor is it intended to limit the scope of this disclosure.

[0006] The purpose of this disclosure is to provide a technical solution that enhances downlink (DL) MU-MIMO reception for co-scheduled UEs by performing inter-user inference elimination based on an appropriately generated DCI.

[0007] The above-mentioned objectives are achieved by the features of the independent claims in the appended claims. Further embodiments and examples will be apparent from the dependent claims, specific embodiments, and drawings.

[0008] According to a first aspect, a UE (User Equipment) in a wireless communication network is provided. The UE includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least the following: First, the UE transmits UE-related information to a network node in the wireless communication network. The UE-related information indicates that the UE is capable of supporting DL MU-MIMO reception. Next, the UE receives a DCI (Distributed Modulation Reference Signal) from the network node, the DCI indicating at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicating at least one of the following: a modulation scheme applied to each of the at least one group of co-scheduled UEs, and a demodulation reference signal (DMRS) initialization value for each of the at least one group of co-scheduled UEs. Afterward, the UE configures DL MU-MIMO reception based on the received DCI. By using the DCI, the UE can effectively (in terms of inter-user inference cancellation) achieve DL MU-MIMO reception together with other co-scheduled UEs.

[0009] In one example embodiment of the first aspect, the UE-related information further indicates at least one of the following: the maximum number of groups of co-scheduled UEs, wherein the UEs in the co-scheduled groups are capable of supporting DL MU-MIMO reception; the total number of MIMO layers, wherein the MIMO layers are supported by the UEs for DL ​​MU-MIMO reception; and the maximum modulation index supported by the UE. By using this additional information from the UE, the network node can generate a more suitable DCI for the UE.

[0010] In one example embodiment of the first aspect, the DCI also indicates a DMRS initialization value for the UE that is the same as or different from the DMRS initialization value for each of the at least one group of co-scheduled UEs. By doing so, network nodes can configure a UE to use a DMRS initialization value that is the same as or different from the remaining co-scheduled UEs, which can lead to better network scheduling flexibility.

[0011] In one example embodiment of the first aspect, the UE-related information also indicates the UE's ability to support more than one DMRS sequence, and the DCI further indicates the DMRS sequence for the UE and each of at least one group of co-scheduled UEs. This additional information may also allow network nodes to generate a more suitable DCI for the UE.

[0012] In one example embodiment of the first aspect, the DMRS sequence is the same or different for each UE and at least one of the co-scheduled UEs. This can again lead to better network scheduling flexibility.

[0013] In one example embodiment of the first aspect, the DCI also indicates a modulation scheme for the UE that is the same as or different from the modulation scheme for each of the at least one group of co-scheduled UEs. This can further improve network scheduling flexibility.

[0014] According to a second aspect, a network node in a wireless communication network is provided. The network node includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network node to perform at least the following: First, the network node receives UE-related information from a UE in the wireless communication network. The UE-related information indicates that the UE is capable of supporting DL MU-MIMO reception. Next, the network node uses the UE-related information to generate a DCI for the UE. More specifically, the DCI indicates at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicates at least one of the following: a modulation scheme applied to each group of co-scheduled UEs; and a DMRS initialization value for each group of co-scheduled UEs. Thereafter, the network node transmits the DCI to the UE. By using the DCI, the network node can configure the UE to achieve efficient (in terms of user-inferred cancellation) DL MU-MIMO reception together with other co-scheduled UEs.

[0015] In one example embodiment of the second aspect, the UE-related information also indicates at least one of the following: the maximum number of groups of co-scheduled UEs, where the UEs in the co-scheduled groups are capable of supporting DL MU-MIMO reception; the total number of MIMO layers, which are supported by the UEs for DL ​​MU-MIMO reception; and the maximum modulation index supported by the UE. By using this additional information from the UE, the network node can generate a more suitable DCI for the UE.

[0016] In one example embodiment of the second aspect, the DCI also indicates a DMRS initialization value for the UE that is the same as or different from the DMRS initialization value for each of the at least one group of co-scheduled UEs. By doing so, network nodes can configure a UE to use a DMRS initialization value that is the same as or different from the remaining co-scheduled UEs, which can lead to better network scheduling flexibility.

[0017] In one example embodiment of the second aspect, the UE-related information also indicates the UE's ability to support more than one DMRS sequence, and the DCI further indicates the DMRS sequence for the UE and each of at least one group of co-scheduled UEs. This additional information can also allow network nodes to generate a more suitable DCI for the UE.

[0018] In one example embodiment of the second aspect, the DMRS sequence is the same or different for each UE and at least one of the co-scheduled UEs. This can again lead to better network scheduling flexibility.

[0019] In one example embodiment of the second aspect, the DCI also indicates a modulation scheme for the UE, which may be the same as or different from the modulation scheme for each of at least one group of co-scheduled UEs. This can further improve network scheduling flexibility.

[0020] According to a third aspect, a method for operating a UE in a wireless communication network is provided. The method begins with the step of transmitting UE-related information to a network node in the wireless communication network. The UE-related information indicates that the UE is capable of supporting DL MU-MIMO reception. Next, the method proceeds to the step of receiving a Direct Message Interface (DCI) from the network node, the DCI indicating at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and further indicating at least one of the following: a modulation scheme applied to each of the at least one group of co-scheduled UEs, and a DMRS initialization value for each of the at least one group of co-scheduled UEs. Afterwards, the method proceeds to the step of configuring DL MU-MIMO reception based on the received DCI. By using the DCI, the UE can effectively (in terms of inter-user inference cancellation) achieve DL MU-MIMO reception together with other co-scheduled UEs.

[0021] According to a fourth aspect, a method for operating a network node in a wireless communication network is provided. The method begins with the step of receiving UE-related information from a UE in the wireless communication network. The UE-related information indicates that the UE supports DL MU-MIMO reception. The method then proceeds to the step of generating a DCI for the UE using the UE-related information. The DCI indicates at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicates at least one of the following: a modulation scheme applied to each of the at least one group of co-scheduled UEs; and a DMRS initialization value for each of the at least one group of co-scheduled UEs. Subsequently, the method proceeds to the step of transmitting the DCI to the UE. By using the DCI, the network node can configure the UE to achieve efficient (in terms of user-inferred cancellation) DL MU-MIMO reception together with other co-scheduled UEs.

[0022] According to a fifth aspect, a computer program product is provided. The computer program product includes a computer-readable storage medium storing computer code. The computer code is executed by at least one processor, causing the at least one processor to perform the method according to the third aspect. By using such a computer program product, the implementation of the method according to the third aspect in any user interface (UE) (such as the UE according to the first aspect) can be simplified.

[0023] According to a sixth aspect, a computer program product is provided. The computer program product includes a computer-readable storage medium storing computer code. The computer code is executed by at least one processor, causing the at least one processor to perform the method according to the fourth aspect. By using this computer program product, the implementation of the method according to the fourth aspect in any network node (such as the network node according to the second aspect) can be simplified.

[0024] According to a seventh aspect, a UE in a wireless communication network is provided. The UE includes components for transmitting UE-related information to a network node in the wireless communication network. The UE-related information indicates that the UE is capable of supporting DL MU-MIMO reception. The UE also includes components for receiving a Direct Context Interface (DCI) from the network node, the DCI indicating at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and further indicating at least one of the following: a modulation scheme applied to each of the at least one group of co-scheduled UEs, and a DMRS initialization value for each of the at least one group of co-scheduled UEs. The UE also includes components for configuring DL MU-MIMO reception based on the received DCI. By using the DCI, the UE can effectively achieve DL MU-MIMO reception (in terms of inter-user inference cancellation) together with other co-scheduled UEs.

[0025] According to an eighth aspect, a network node in a wireless communication network is provided. The network node includes components for receiving UE-related information from a UE in the wireless communication network. The UE-related information indicates that the UE is capable of supporting DL MU-MIMO reception. The network node also includes components for generating a Directional Control Interface (DCI) for the UE based on the UE-related information. More specifically, the DCI indicates at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicates at least one of the following: a modulation scheme applied to each of the at least one group of co-scheduled UEs; and a DMRS initialization value for each of the at least one group of co-scheduled UEs. The network node also includes components for transmitting the DCI to the UE. By using the DCI, the network node can configure the UE to achieve efficient (in terms of user-inferred cancellation) DL MU-MIMO reception together with other co-scheduled UEs.

[0026] Other features and advantages of this disclosure will become apparent from reading the following detailed description and viewing the accompanying drawings. Attached Figure Description

[0027] This disclosure is explained below with reference to the accompanying drawings, in which: Figure 1 A block diagram of a UE according to an example embodiment is shown; Figure 2 An example embodiment of operation is shown. Figure 1 The flowchart of the UE method; Figure 3 A block diagram of a network node according to an example embodiment is shown; Figure 4 An example embodiment of operation is shown. Figure 3 A flowchart of the network node method; Figure 5 A block diagram of a wireless communication system according to an example embodiment is shown, wherein DCI signaling is used to achieve DL MU-MIMO reception in the case of two groups of co-scheduled UEs; and Figure 6 A block diagram of a wireless communication system according to another example embodiment is shown, wherein DCI signaling is used to achieve DL MU-MIMO reception in the case of three groups of UEs that are jointly scheduled. Detailed Implementation

[0028] Various embodiments of the present disclosure are described in further detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many other forms and should not be construed as limited to any particular structure or function discussed in the following description. Rather, these embodiments are provided to make the description of the present disclosure detailed and complete.

[0029] As will be apparent to those skilled in the art from the detailed description, the scope of this disclosure covers any embodiment of the present disclosure, whether implemented independently or in conjunction with any other embodiment of the present disclosure. For example, the apparatus and methods disclosed herein can be implemented in practice using any number of the embodiments provided herein. Furthermore, it should be understood that any embodiment of the present disclosure can be implemented using one or more elements set forth in the appended claims.

[0030] Unless otherwise stated, any embodiment described herein as an "example embodiment" should not be construed as preferred or having an advantage over other embodiments.

[0031] According to the example embodiments disclosed herein, a user equipment (UE) can refer to an electronic computing device configured to perform wireless communication. A UE can be implemented as a mobile station, mobile terminal, mobile subscriber unit, mobile phone, cellular phone, smartphone, cordless phone, personal digital assistant (PDA), wireless communication device, desktop computer, laptop computer, tablet computer, gaming device, netbook, smartbook, ultrabook, medical mobile device or equipment, biometric sensor, wearable device (e.g., smartwatch, smart glasses, smart wristband, etc.), entertainment device (e.g., audio player, video player, etc.), vehicle component or sensor (e.g., driver assistance system), smart meter / sensor, unmanned vehicle (e.g., industrial robot, quadcopter, etc.) and its components (e.g., autonomous vehicle computer), industrial manufacturing equipment, global positioning system (GPS) device, Internet of Things (IoT) device, industrial IoT (IIoT) device, machine type communication (MTC) device, a set of massive IoT (MIoT) or massive MTC (mMTC) devices / sensors, or any other suitable mobile device configured to support wireless communication. In some embodiments, a UE can refer to at least two juxtaposed and interconnected UEs as defined herein.

[0032] As used in the example embodiments disclosed herein, a network node can refer to a fixed communication point or communication node for a UE in a specific wireless communication network. More specifically, a network node can be used to connect a UE to a data network (DN) via a core network (CN) and can be referred to as a base transceiver unit (BTS) in 2G communication technology, a NodeB in 3G communication technology, an evolved NodeB (eNodeB or eNB) in 4G communication technology, and a gNB in ​​5G New Radio (NR) communication technology. A network node can serve different types of cells, such as macrocells, microcells, picocells, femtocells, and / or other cell types. A macrocell can cover a relatively large geographic area (e.g., a radius of at least several kilometers). For example, a microcell can cover a geographic area with a radius of less than two kilometers. A picocell can cover a relatively small geographic area, such as an office, shopping mall, train station, stock exchange, etc. A femtocell can cover even smaller geographic areas (e.g., a home). Accordingly, a network node serving a macrocell can be referred to as a macro node, a network node serving a microcell can be referred to as a micro node, and so on.

[0033] According to the example embodiments disclosed herein, the wireless communication network in which the UE and network nodes communicate with each other can refer to a cellular or mobile network, a wireless local area network (WLAN), a wireless personal area network (WPAN), a wireless wide area network (WWAN), a satellite communication (SATCOM) system, or any other type of wireless communication network. Each of these types of wireless communication networks supports wireless communication according to one or more communication protocol standards. For example, a cellular network can operate according to the Global System for Mobile Communications (GSM) standard, the Code Division Multiple Access (CDMA) standard, the Wideband Code Division Multiple Access (WCDM) standard, the Time Division Multiple Access (TDMA) standard, or any other communication protocol standard; a WLAN can operate according to one or more versions of the IEEE 802.11 standard; a WPAN can operate according to the Infrared Data Association (IrDA), Wireless USB, Bluetooth, or ZigBee standards; and a WWAN can operate according to the Global Microwave Access Interoperability (WiMAX) standard.

[0034] Data transmission between UEs, between network nodes, or between a UE and a network node can be performed using MIMO technology. MIMO technology involves employing multiple transmit antennas at the transmitting entity (e.g., a UE or a network node) and multiple receive antennas at the receiving entity (e.g., another UE or a network node) for data transmission. The MIMO channel formed by the transmit and receive antennas can be decomposed into spatial layers (also known as MIMO layers). MIMO layers can be used to transmit data in parallel to achieve higher throughput and / or to transmit data redundantly to achieve greater reliability. MIMO layers may experience various detrimental channel conditions (e.g., fading, multipath, interference effects, etc.), and therefore they may achieve different signal-to-noise ratios (SNR) or signal-to-interference-plus-noise ratios (SINR). The SNR or SINR of each MIMO layer determines its transmission capacity, which is typically quantified by the specific data rate that can be reliably transmitted on the MIMO layer. For time-varying wireless channels, channel conditions change over time, and the SNR or SINR of each MIMO layer also changes over time. The different SNRs or SINRs of MIMO layers, coupled with the time-varying nature of the SNRs or SINRs for each MIMO layer, make efficient data transmission in MIMO systems challenging.

[0035] Single-user MIMO (SU-MIMO) technology concentrates all streams from an antenna array onto a single user device (UE). SU-MIMO allows data to be transmitted to a UE simultaneously via more than one data stream. The advantages of SU-MIMO are the absence of interference and easier implementation of radio channel estimation. However, its disadvantages include the ability to serve only one UE at a time, and the inability to use MIMO if the transmission matrix is ​​uncorrelated.

[0036] Multi-user MIMO (MU-MIMO) utilizes more than one antenna to simultaneously create multiple connections to different UEs to improve network capacity. In other words, MU-MIMO technology is used in environments where many users attempt to connect to a wireless communication network simultaneously. It allows multiple users to access network nodes concurrently. Therefore, MU-MIMO technology involves the simultaneous use of multiple data streams from different co-scheduled UEs. The advantage of MU-MIMO is that the number of antennas in the co-scheduled UEs does not need to increase; however, the co-scheduled UEs should be able to send channel estimates to the serving network node, and the serving network node needs to find the optimal UE for this MU-MIMO communication, which can be challenging. Furthermore, the problem of so-called inter-user interference must be addressed to provide effective DL MU-MIMO reception at the co-scheduled UEs.

[0037] The example embodiments disclosed herein provide a technical solution that enhances downlink (DL) MU-MIMO reception for co-scheduled UEs by performing inter-user inference cancellation based on appropriately generated downlink control information (DCI). More specifically, in response to UE-related information (indicating that the target UE is configured for DL ​​MU-MIMO reception along with other co-scheduled UEs), the DCI is generated by a network node and transmitted to the target UE. The DCI further indicates at least one group of co-scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicates at least one of the following: the modulation scheme applied to each group of co-scheduled UEs, and the DMRS initialization value for each group of co-scheduled UEs. By using the DCI, the target UE can efficiently achieve DL MU-MIMO reception (in terms of inter-user inference cancellation) with the co-scheduled UEs.

[0038] Figure 1 A block diagram of a UE 100 according to an example embodiment is shown. The UE 100 is intended to communicate with network nodes and / or one or more other UEs in any of the aforementioned communication networks. Figure 1 As shown, UE 100 includes a processor 102 and a memory 104. The memory 104 stores processor-executable instructions 206, which, when executed by the processor 102, cause the processor 102 to perform various aspects of this disclosure, as will be described in more detail below. It should be noted that in Figure 1 The number, arrangement, and interconnection of the building elements constituting UE 100 shown are not intended to be any limitation of this disclosure, but are merely intended to provide a general idea of ​​how the building elements can be implemented within UE 100. For example, processor 102 may be replaced by several processors, and memory 104 may be replaced by several removable and / or fixed storage devices, depending on the specific application. Furthermore, it is assumed that processor 102 is capable of performing various operations required for the reception and transmission of data, such as signal modulation / demodulation, encoding / decoding, etc. In another embodiment, UE 100 may also include a separate transceiver unit comprising an antenna array and controlled by processor 102.

[0039] Processor 102 can be implemented as a CPU, a general-purpose processor, a special-purpose processor, a microcontroller, a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), a complex programmable logic device, etc. It should also be noted that processor 102 can be implemented as any combination of one or more of the foregoing. As an example, processor 102 can be a combination of two or more microprocessors.

[0040] The memory 104 can be implemented as a classic non-volatile or volatile memory used in modern electronic computing machines. As examples, non-volatile memory may include read-only memory (ROM), ferroelectric random access memory (RAM), programmable ROM (PROM), electrically erasable PROM (EEPROM), solid-state drives (SSD), flash memory, disk storage devices (such as hard disk drives and magnetic tape), optical disk storage devices (such as CDs, DVDs, and Blu-ray discs), etc. As for volatile memory, examples include dynamic RAM, synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), static RAM, etc. The processor-executable instructions 106 stored in memory 104 can be configured to cause processor 102 to execute computer-executable program code of various aspects of this disclosure. The computer-executable program code for performing the operations or steps of various aspects of this disclosure can be written in any combination of one or more programming languages, such as Java, C++, etc. In some examples, the computer-executable program code can be in the form of a high-level language or in a pre-compiled form, and is generated on the fly by an interpreter (also pre-stored in memory 104).

[0041] Figure 2A flowchart of a method 200 for operating a UE 100 according to an example embodiment is shown. Method 200 begins at step S202, where processor 102 transmits UE-related information (e.g., by using the antenna array of a transceiver unit) to a network node (e.g., a BTS or gNB) in a wireless communication network. The UE-related information indicates that the UE is configured to support DL MU-MIMO reception. For example, such an indication may be in the form of specific bit values ​​or flag sets transmitted to the network node via dedicated signaling (e.g., Radio Resource Control (RRC) signaling). Furthermore, step S202 may be initiated by the UE 100 itself (e.g., when it enters a new cell) or in response to a corresponding request from the network node. Next, method 200 proceeds to step S204, where processor 102 receives (e.g., by using the antenna array of a transceiver unit) DCI from the network node. The DCI indicates one or more groups of jointly scheduled UEs served by the network node for DL ​​MU-MIMO reception, and also indicates one or more of the following: the modulation scheme applied to each group of jointly scheduled UEs (e.g., Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM) with different modulation orders (MO) or indices, etc.); and the DMRS initialization value for each group of jointly scheduled UEs. The DMRS initialization value is well known in the art (e.g., see the “c_init” value in 3GPP TS 38.2117.4.1.1.1), and it can consist of various components such as the physical cell ID, the synchronization signal block (SSB) index, and the half-frame number. That is, by decoding a certain DMRS, UE 100 can derive the SSB index and the half-frame number. It should be noted that step S204 can also be performed using any suitable dedicated signaling (e.g., RRC signaling). Next, method 200 proceeds to step S206, where processor 102 configures DL MU-MIMO reception based on the received DCI. More specifically, processor 102 uses the DCI to appropriately determine demodulation / processing parameters for the DL signal or DL ​​channel (e.g., Physical Data Sharing Channel (PDSCH)). In other words, such a configured DCI improves overall channel estimation performance, allowing UE 100 to determine its advanced receiver processing and related parameters, making it possible to eliminate / suppress inter-user interference caused by multiple groups of co-scheduled UEs.

[0042] As for the DCI itself, it can be configured as a tabular data structure comprising a set of indexed bit fields, each indexed bit field being associated with a certain MU-MIMO setting (e.g., DMRS initialization value or some combination of sequence and modulation scheme). The DCI can additionally instruct the processor 102 to configure the indexes of the bit fields to be considered when receiving the DL MU-MIMO in step S206 of method 200. A non-limiting example of a tabular DCI is given below as Table 1.

[0043] Table 1. DCI field used for DL ​​MU-MIMO reception in the case of two groups of UEs being jointly scheduled.

[0044] It should be noted that the bit fields with indices 0-6 in Table 1 refer to the use case where there is only a single group of UEs being jointly scheduled. These bit fields may not be indicated in Table 1 at all, as long as the network nodes can form more than one group of UEs; in this case, the remaining bit fields can be appropriately re-indexed, or in other words, re-numbered.

[0045] As shown in Table 1, each of the two groups of co-scheduled UEs can be configured with the same or different modulation schemes. The same applies to the DMRS initialization values ​​or sequences; that is, each of the two groups of co-scheduled UEs can be provided with the same or different DMRS initialization values ​​or sequences. For those UEs whose DMRS initialization values ​​are given, channel estimation can be performed. Based on this, the interference covariance matrix can be calculated, and the UE can use it, for example, to define a noise whitening filter and use it in receiver processing. Thus, interference between co-scheduled UEs in one or more groups of co-scheduled UEs can be removed more accurately in UE 100.

[0046] Typically, the serving network node determines whether the DMRS sequence is initialized with the same initialization value for all UEs in the serving cell. If the same DMRS initialization value is applied within the cell, UE 100 can reduce its advanced receiver processing complexity (it is neither necessary nor possible to perform additional effective channel (including precoding and radio channel) estimation associated with interference from co-scheduled UEs). If different DMRS initialization values ​​are applied to groups(s) of co-scheduled UEs within the serving cell, or if groups(s) of co-scheduled UEs with different DMRS initialization values ​​are associated with neighboring cells, the corresponding DMRS initialization value is indicated for UE 100. By doing so, UE 100 can estimate the effective channels associated with interference from / to PDSCH transmissions from co-scheduled UEs to UE 100. Of course, this effective channel estimation provides an approximation of the accurate UE / PDSCH interference for co-scheduled UEs (even if the modulation order is indicated), because UE 100 also needs to know the DMRS type (e.g., type 1 / 2 or type 1 / type 2) and the number of MIMO layers for the co-scheduled UEs to more accurately estimate the actual effective channel associated with the co-scheduled UEs. An alternative scenario could be that a first group of co-scheduled UEs uses the same DMRS initialization values ​​as UE 100, and a second group of co-scheduled UEs uses different DMRS initialization values ​​compared to UE 100, where the first group of co-scheduled UEs is in the same cell as UE 100, and the second group is in neighboring cells. Given that the network implementation itself allows for this pairing, this would provide the network scheduler with additional flexibility in pairing these different groups in the serving cell and / or neighboring cells.

[0047] Regarding the possibility of using the same or different modulation schemes for UE 100 and co-scheduled UEs in one or more groups, it should be noted that from UE 100's perspective, using the same modulation scheme may potentially lead to a reduction in the complexity of its receiver processing, for example, a reduced maximum likelihood (ML) type of receiver processing. If UE 100 is co-scheduled with co-scheduled UEs in different groups with different modulation orders, and UE 100 is unaware of the modulation order, interference-related information is less accurate than if the modulation order were known. From the network node's perspective, it is always optimal if the network scheduler determines that the co-scheduled UE / PDSCH transmission paired with UE 100 (with advanced receiver processing capabilities) and also indicates that the modulation order associated with the co-scheduled UE(s) group(s) is permitted. Therefore, the network node can maximize the utilization of UE processing capabilities for DL ​​MU-MIMO reception, thereby achieving enhanced spectral efficiency and higher data rates in the serving cell.

[0048] It is worth noting that this disclosure is not limited to the two groups of co-scheduled UEs indicated in Table 1. In other embodiments, the number of co-scheduled UE groups indicated in the DCI may depend on the capabilities of UE 100 itself. More specifically, the processor 102 of UE 100 may additionally indicate the maximum number of co-scheduled UE groups in the UE-related information, wherein UE 100, together with the co-scheduled UE groups, is configured to support efficient (in terms of inter-user inference cancellation) DLMU-MIMO reception. Additionally, the processor 102 of UE 100 may indicate in the UE-related information the total number of MIMO layers supported by UE 100 for DLMU-MIMO reception, the maximum modulation index or order supported by UE 100, and the ability of UE 100 to support more than one RS sequence. By using all this additional information from UE 100, the network node can generate the most suitable DCI for UE 100.

[0049] Another embodiment is possible, in which the DCI also indicates the modulation scheme for UE 100 itself. In this embodiment, the modulation scheme to be used by UE 100 may be the same as or different from the modulation scheme assigned to each group of co-scheduled UEs. Meanwhile, UE 100 may derive information about its own MIMO-layer-associated modulation scheme based on the DL authorization provided by the network node.

[0050] Figure 3 A block diagram of a network node 300 according to an example embodiment is shown. The network node 300 is intended to communicate with the UE 100 in any of the above-described communication networks. Figure 3 As shown, network node 300 includes processor 302 and memory 304. Memory 304 stores processor-executable instructions 306, which, when executed by processor 302, cause processor 302 to implement various aspects of this disclosure, as will be described in more detail below. It should be noted again that... Figure 3 The number, arrangement, and interconnection of the building elements constituting network node 300 shown are not intended to be any limitation of this disclosure, but are merely intended to provide a general concept of how building elements can be implemented within network node 300. Typically, processor 302, memory 304, and processor executable instructions 306 can be implemented in the same or similar manner as processor 102, memory 104, and processor executable instructions 106, respectively.

[0051] Figure 4A flowchart of a method 400 for operating a network node 300 according to an example embodiment is shown. Method 400 begins at step S402, where processor 302 receives UE-related information from processor 102 of UE 100 in a wireless communication network. As previously described, the UE-related information indicates that UE 100 supports DL MU-MIMO reception. Additionally, the UE-related information may indicate the maximum number of groups of co-scheduled UEs for which UE 100 can effectively support DL MU-MIMO reception, the total number of MIMO layers supported by UE 100, the maximum modulation index or order supported by UE 100, and / or the ability of UE 100 to support more than one RS sequence. Next, method 400 proceeds to step S404, where processor 302 uses the received UE-related information to appropriately generate a DCI for UE 100. For example, the DCI may be generated as discussed in Table 1 above. Afterward, method 400 proceeds to step S406, where processor 302 transmits the DCI to processor 102 of UE 100.

[0052] Figure 5 A block diagram of a wireless communication system 500 according to an example embodiment is shown. Figure 5 As shown, in the case of two groups 502 and 504 of co-scheduled UEs (e.g., mobile phones), DCI signaling is used in system 500 to implement DLMU-MIMO reception. Assume the target UE (i.e., the UE that wants to initiate DL MU-MIMO reception) is included in the first co-scheduled UE group 502, and network node 506 (e.g., gNB) generates a DCI according to method 400 and transmits it to the target UE. The DCI can be implemented as shown in Table 1, or it can simply indicate the two groups 502 and 504 of the co-scheduled UE and group-specific information in the form of the message: “Group #1=MO#x” and “Group #2=MO#y” (where each of “x” and “y” refers to a MO or index of the same modulation scheme (e.g., QAM)). By using the DCI, the target UE can properly configure DL MU-MIMO reception (i.e., properly perform DL channel estimation and inter-user inference cancellation).

[0053] Figure 6 A block diagram of a wireless communication system 600 according to another example embodiment is shown. Figure 6As shown, in the case of three groups 602, 604, and 606 of co-scheduled UEs (e.g., mobile phones), DCI signaling is used in system 600 to implement DL MU-MIMO reception. Assume the target UE (i.e., the UE that wants to initiate DL MU-MIMO reception) is included in the first co-scheduled UE group 602, and network node 608 (e.g., gNB) generates a DCI according to method 400 and transmits it to the target UE. The DCI can be implemented as shown in Table 1, or it can simply indicate the three groups 602, 604, and 606 of the co-scheduled UEs and group-specific information in the form of a message: “Group #1=MO#x”, “Group #2=MO#z”, and “Group #3=MO#y” (where each of “x”, “y”, and “z” refers to a MO or index of the same modulation scheme (e.g., QAM). By using the DCI, the target UE can properly configure DL MU-MIMO reception (i.e., properly perform DL channel estimation and inter-user inference cancellation).

[0054] It should be noted that each step or operation, or any combination of steps or operations, of methods 200 and 400 can be implemented by various means, such as hardware, firmware, and / or software. As an example, one or more of the above steps or operations can be embodied by processor-executable instructions, data structures, program modules, and other suitable data representations. Furthermore, the processor-executable instructions embodying the above steps or operations can be stored on corresponding data carriers and executed by processors 102 and 302, respectively. The data carrier can be implemented as any computer-readable storage medium configured to be readable by the at least one processor to execute the processor-executable instructions. Such computer-readable storage media can include volatile and non-volatile media, removable and non-removable media. As an example, and not a limitation, a computer-readable medium includes media implemented in any method or technology suitable for storing information. More specifically, practical examples of computer-readable media include, but are not limited to, information delivery media, RAM, ROM, EPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD), holographic media or other optical disc storage, magnetic tape, magnetic tape cassette, disk storage, and other magnetic storage devices.

[0055] Although exemplary embodiments of this disclosure have been described herein, it should be noted that various changes and modifications may be made to the embodiments of this disclosure without departing from the scope of legal protection defined by the appended claims. In the appended claims, the word "comprising" does not exclude other elements or operations, and the indefinite articles "a" or "an" do not exclude a plurality. The fact that certain measures are recited in mutually different dependent claims does not imply that a combination of these measures cannot be used advantageously.

Claims

1. A user equipment (UE) in a wireless communication network, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the UE to at least: Transmit UE-related information to network nodes in the wireless communication network, wherein the UE-related information indicates that the UE can support downlink (DL) multiple user multiple input multiple output (MU-MIMO) reception; The network node receives downlink control information (DCI), the DCI indicating at least one group of jointly scheduled UEs served by the network node for DL ​​MU-MIMO reception, and the DCI also indicating at least one of the following: The modulation scheme applied to each of the at least one group of jointly scheduled UEs; as well as Initialization value of demodulation reference signal (DMRS) for each of the at least one group of jointly scheduled UEs; as well as Based on the DCI, configure the DL MU-MIMO receiver.

2. The UE according to claim 1, wherein the UE-related information further indicates at least one of the following: The maximum number of groups of UEs that are jointly scheduled, wherein the UEs in the groups of jointly scheduled UEs are capable of supporting the DL MU-MIMO reception; The total number of MIMO layers, which are supported by the UE for DL ​​MU-MIMO reception; and The maximum modulation index supported by the UE.

3. The UE according to claim 1 or 2, wherein the DCI further indicates a DMRS initialization value for the UE, the DMRS initialization value for the UE being the same as or different from the DMRS initialization value for each of the at least one group of co-scheduled UEs.

4. The UE according to any one of claims 1 to 3, wherein the UE-related information further indicates the UE's ability to support more than one DMRS sequence, and wherein the DCI further indicates the DMRS sequence for the UE and each of the at least one group of co-scheduled UEs.

5. The UE of claim 4, wherein the DMRS sequence is the same or different for the UE and each of the at least one group of co-scheduled UEs.

6. The UE according to any one of claims 1 to 5, wherein the DCI further indicates a modulation scheme for the UE, the modulation scheme for the UE being the same as or different from the modulation scheme for each of the at least one group of co-scheduled UEs.

7. A network node in a wireless communication network, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the network node to at least: Receive UE-related information from the user equipment (UE) in the wireless communication network, the UE-related information indicating that the UE can support downlink (DL) multiple user multiple input multiple output (MU-MIMO) reception; Based on the UE-related information, downlink control information (DCI) is generated. The DCI indicates at least one group of jointly scheduled UEs served by the network node for DL ​​MU-MIMO reception. The DCI also indicates at least one of the following: The modulation scheme applied to each of the at least one group of jointly scheduled UEs; as well as Initialization value of demodulation reference signal (DMRS) for each of the at least one group of jointly scheduled UEs; as well as The DCI is transmitted to the UE.

8. The network node of claim 7, wherein the UE-related information further indicates at least one of the following: The maximum number of groups of UEs that are jointly scheduled, wherein the UEs in the groups of jointly scheduled UEs are capable of supporting the DL MU-MIMO reception; The total number of MIMO layers, which are supported by the UE for DL ​​MU-MIMO reception; and The maximum modulation index supported by the UE.

9. The network node of claim 7 or 8, wherein the DCI further indicates a DMRS initialization value for the UE, the DMRS initialization value for the UE being the same as or different from the DMRS initialization value for each of the at least one group of co-scheduled UEs.

10. The network node according to any one of claims 7 to 9, wherein the UE-related information further indicates the UE's ability to support more than one DMRS sequence, and wherein the DCI further indicates a DMRS sequence for the UE and each of the at least one group of co-scheduled UEs.

11. The network node of claim 10, wherein the DMRS sequence is the same or different for the UE and each of the at least one group of co-scheduled UEs.

12. The network node according to any one of claims 6 to 9, wherein the DCI further indicates a modulation scheme for the UE, the modulation scheme for the UE being the same as or different from the modulation scheme for each of the at least one group of co-scheduled UEs.

13. A method for operating a user equipment (UE) in a wireless communication network, comprising: Transmit UE-related information to network nodes in the wireless communication network, wherein the UE-related information indicates that the UE can support downlink (DL) multiple user multiple input multiple output (MU-MIMO) reception; The network node receives downlink control information (DCI), the DCI indicating at least one group of jointly scheduled UEs served by the network node for DL ​​MU-MIMO reception, and the DCI also indicating at least one of the following: The modulation scheme applied to each of the at least one group of jointly scheduled UEs; as well as Initialization value of demodulation reference signal (DMRS) for each of the at least one group of jointly scheduled UEs; as well as Based on the DCI, configure the DL MU-MIMO receiver.

14. A method for operating a network node in a wireless communication network, comprising: Receive UE-related information from the user equipment (UE) in the wireless communication network, the UE-related information indicating that the UE can support downlink (DL) multiple user multiple input multiple output (MU-MIMO) reception; Based on the UE-related information, downlink control information (DCI) is generated. The DCI indicates at least one group of jointly scheduled UEs served by the network node for DL ​​MU-MIMO reception. The DCI also indicates at least one of the following: The modulation scheme applied to each of the at least one group of jointly scheduled UEs; as well as Initialization value of demodulation reference signal (DMRS) for each of the at least one group of jointly scheduled UEs; as well as The DCI is transmitted to the UE.

15. A computer program product comprising a computer-readable storage medium storing computer code that, when executed by at least one processor, causes the at least one processor to perform the method of claim 13.

16. A computer program product comprising a computer-readable storage medium storing computer code that, when executed by at least one processor, causes the at least one processor to perform the method of claim 14.

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