FIELD

The present disclosure relates to wireless communications, and in particular, to reference signal port assignment.

BACKGROUND

The Third Generation Partnership Project (3 GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs.

For data transmission on physical downlink shared channel (PDSCH) in 5G NR, demodulation reference signal (DMRS) is used for channel estimation and demodulation at a receiver, e.g., a WD. Each layer for a WD is typically associated with an assigned DMRS port. In some applications, either single or multiple DMRS symbols, with one or more additional symbol associated with each DMRS symbol, are reserved to form multiple DMRS ports. FIG. 1 shows a typical “1 + 1” DMRS configuration, in which four DMRS ports can be formed from the given configuration.

In a multi user multiple input multiple output (MU-MIMO) context, the number of DMRS ports available is generally less than the total of co-scheduled layers. For example, four co-scheduled WDs with two layers per WD can support 8- layers transmissions in total. As shown in the “1+1” DMRS configuration example of FIG. 1, there are four DMRS ports available from this configuration. Given that each WD requires 2 DMRS ports each to support two-layer transmissions, it must follow that the four DMRS ports have to be assigned more than once to the co- scheduled WDs. Further, orthogonal (or different) DMRS ports may be preferred for WDs that are not spatially separated (i.e., not separated more than a predetermined separation parameter) for a predetermined channel estimation. For WDs with spatially separated (i.e., separated more than a predetermine separation parameter), the DMRS ports may be reused since interference introduced from the same DMRS ports of the other WDs may be considered negligible.

In addition, if there is more than one layer of data transmissions for a WD, there are limitations on associated DMRS ports. For example, Table 1 below enumerates available DMRS ports assignments, e.g., using the “1 + 1” DMRS configuration. For two-layer data transmissions, DMRS ports (0,1), (0,2), or (2,3) are applicable if the number of DMRS CDM group(s) without data is two. Other combinations such as (0,3), (1,3), or (1,2) are not possible. For 3-layer transmission, DMRS ports (0-2) are possible. Other combinations such as (1-3), (0,2,3), or (0,1,3) may not possible. In other words, allocation of a limited number of DMRS ports among co-scheduled layers follows the 3GPP specifications on a per WD basis as well.

Table 1: Antenna port(s) (1000 + DMRS port), dmrs-Type= , maxLength=

In technical specifications corresponding to 3GPP Release 15 (Rel-15), various PDSCH DMRS configurations including different configurations types, DMRS (addition-) positions, with either single or double symbol, are described for the network to configure. However, the technical specifications do not suggest how to configure and/or assign PDSCH DMRS to WDs, e.g., to achieve a predetermined performance, especially in the context of MU-MIMO.

In one example, to support multiple MU-MIMO WDs, there are only up to four antenna ports available for the Type-1 DMRS configuration with single symbol. Identical DMRS port assignment and blind DMRS ports assignments sacrifices performance due to incurred interferences from re-used DMRS ports among multiple WDs.

Further, relying on sorted pairwise precoding matrix indicator (PMI) distance (PMID) to assign DMRS ports accordingly may result in DMRS ports assignment that are detrimental due to the cyclic nature of the PMIs and inflexibility to WD ranks, DMRS configurations, etc.

SUMMARY

Some embodiments advantageously provide methods, systems, and apparatuses for determining (e.g., assigning) a signaling port such as a DMRS port). The determined signaling port may be used in MU-MIMO networks. In some embodiments, at least a signaling port such as a DMRS port is determined (i.e., assigned) when a number of signaling ports (e.g., antenna ports) is limited and signaling ports for MU-MIMO WDs are re-used.

In some other embodiments, a method (e.g., a systematic method) to determine/assign DMRS ports for MU-MIMO WDs, specifically, taking at least one of the following factors into consideration: • WDs may be of different ranks (or different number of layers for downlink (DL) transmissions);

• DMRS configurations may be different (e.g., not limited to how many DMRS ports in total are available);

• Per-rank DMRS port(s) assignment (i.e., the field “Antenna port(s)” from downlink control information (DCI) 1_1) may be a subset (e.g., a choice) from a plurality of choices; and

• There is no limitation on how many WDs can be supported,

In some embodiments, a spatial relationship of MU-MIMO WDs is established. DMRS ports may be assigned per WD, on the basis of an order established from the spatial relationship. Weights or a number of occupancies of each DMRS port may be re-initialized (e.g., to 0) in the beginning of each time interval (e.g., each transmission time interval (TTI)). For the DMRS assignment of each WD, the network node, e.g., the gNB, performs at least one of the steps below, e.g., based on ranks of the WDs

Step 1: Check and apply balancing of multiplexing groups such as code division multiplexing (CDM) groups;

Step 2: Check and apply balancing of at least one signaling port such as DMRS ports from the least occupied multiplexing group (e.g., CDM group) from Step 1; and

Step 3: Apply a least redundant multiplexing group (e.g., CDM group) and signaling ports (e.g., DMRS ports) such as by referring to a previous DMRS ports assignment (e.g., from a previous WD) if there is a tie following Step 1 and Step 2.

In some other embodiments, the network node may record selected DMRS ports for a next WD, e.g., until all the WDs have been considered.

The embodiments of the present disclosure are beneficial at least because interferences are minimized such as interferences from adjacent MU-MIMO WDs and/or DMRS ports configurations (e.g., WDs and/ DMRS ports configured based on 3GPP standards). In addition, MU-MIMO WDs are supported by re-using signaling ports such as DMRS ports on based on a spatial relationship (e.g., established by pairwise PMIDs from channel state information (CSI) reports. In other words, any transmission schemes may be used using the spatial relationship among WDs (e.g., MU-MIMO WDs). WDs with different ranks, DMRS configurations, and per-rank DMRS port(s) assignment may be supported. Further, there is also no limitation on how many WDs can be supported.

According to one aspect of the present disclosure, a network node in communication with a plurality of multiple user- multiple input multiple output, MU- MIMO, wireless devices is provided. The network node includes processing circuitry configured to: determine an occupancy of a plurality of code division multiplexing, CDM, groups associated with the plurality of MU-MIMO wireless devices, select a first CDM group of the plurality of CDM groups based on the first CDM group being a least occupied CDM group of the plurality of CDM groups, determine an occupancy of demodulation reference signal, DMRS, ports for the first CDM group, and assign at least one DMRS port associated with the first CDM group to a first MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on the occupancy of DMRS ports for the first CDM group where the first MU-MIMO wireless device has a rank of 1 or 2.

According to one or more embodiments of this aspect, the first CDM group is selected based on the first CDM group having fewer assigned DMRS ports than the remaining plurality of CDM groups.

According to one or more embodiments of this aspect, the assignment of the at least one DMRS port associated with the first CDM group is based on the at least one DMRS port having fewer assignments than the remaining DMRS ports in the first CDM group.

According to one or more embodiments of this aspect, the selection of the first CDM group is based on a rank of the first MU-MIMO wireless device.

According to one or more embodiments of this aspect, the first CDM group has a same occupancy as a second CDM group of the plurality of CDM groups, where the plurality of DMRS ports in the first CDM group have a same DMRS port occupancy, and the assignment of the at least one DMRS port associated with the first CDM group is based on a at least one previous DMRS port assignment.

According to one or more embodiments of this aspect, the first CDM group is a least redundant of the plurality of CDM groups when the at least one previous DMRS port assignment is considered, and the at least one DMRS port associated with the first CDM group is a least redundant of the plurality of DMRS ports when the at least one previous DMRS port assignment is considered.

According to one or more embodiments of this aspect, the processing circuitry is further configured to cause transmission of DMRS in the at least one DMRS port associated with the first CDM group.

According to one or more embodiments of this aspect, each of the plurality of MU-MIMO wireless devices are selected for DMRS port assignment according to an ordering that is based on a spatial relationship of the plurality of MU-MIMO wireless devices.

According to one or more embodiments of this aspect, the spatial relationships are based on at least one of: information included in channel state information, CSI, reports associated with the MU-MIMO wireless devices, and pairwise orthogonality of channel responses associated with the plurality of MU-MIMO wireless devices.

According to one or more embodiments of this aspect, the processing circuitry is further configured to assign at least one DMRS port to a second MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on: an updated occupancy of a plurality of CDM groups, an updated occupancy of DMRS ports for one of the plurality of CDM groups, and the updated occupancies being based on the at least one DMRS port assigned to the first MU-MIMO wireless device.

According to one or more embodiments of this aspect, the processing circuitry is further configured to assign predefined DMRS ports to a second MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on the second MU-MIMO wireless device having a rank of 3 or 4.

According to another aspect of the present disclosure, a method implemented by a network node that is in communication with a plurality of multiple user-multiple input multiple output, MU-MIMO, wireless devices is provided. An occupancy of a plurality of code division multiplexing, CDM, groups associated with the plurality of MU-MIMO wireless devices is determined. A first CDM group of the plurality of CDM groups is selected based on the first CDM group being a least occupied CDM group of the plurality of CDM groups. An occupancy of demodulation reference signal, DMRS, ports for the first CDM group is determined. At least one DMRS port associated with the first CDM group is assigned to a first MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on the occupancy of DMRS ports for the first CDM group, the first MU-MIMO wireless device having a rank of 1 or 2.

According to one or more embodiments of this aspect, the first CDM group is selected based on the first CDM group having fewer assigned DMRS ports than the remaining plurality of CDM groups.

According to one or more embodiments of this aspect, the assignment of the at least one DMRS port associated with the first CDM group is based on the at least one DMRS port having fewer assignments than the remaining DMRS ports in the first CDM group.

According to one or more embodiments of this aspect, the selection of the first CDM group is based on a rank of the first MU-MIMO wireless device.

According to one or more embodiments of this aspect, the first CDM group has a same occupancy as a second CDM group of the plurality of CDM groups, where the plurality of DMRS ports in the first CDM group have a same DMRS port occupancy, and where the assignment of the at least one DMRS port associated with the first CDM group is based on a at least one previous DMRS port assignment.

According to one or more embodiments of this aspect, the first CDM group is a least redundant of the plurality of CDM groups when the at least one previous DMRS port assignment is considered, and where the at least one DMRS port associated with the first CDM group is a least redundant of the plurality of DMRS ports when the at least one previous DMRS port assignment is considered.

According to one or more embodiments of this aspect, transmission is caused of DMRS in the at least one DMRS port associated with the first CDM group.

According to one or more embodiments of this aspect, each of the plurality of MU-MIMO wireless devices are selected for DMRS port assignment according to an ordering that is based on a spatial relationship of the plurality of MU-MIMO wireless devices.

According to one or more embodiments of this aspect, the spatial relationships are based on at least one of: information included in channel state information, CSI, reports associated with the MU-MIMO wireless devices, and pairwise orthogonality of channel responses associated with the plurality of MU-MIMO wireless devices. According to one or more embodiments of this aspect, at least one DMRS port is assigned to a second MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on: an updated occupancy of a plurality of CDM groups, an updated occupancy of DMRS ports for one of the plurality of CDM groups, and where the updated occupancies is based on the at least one DMRS port assigned to the first MU-MIMO wireless device.

According to one or more embodiments of this aspect, predefined DMRS ports are assigned to a second MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on the second MU-MIMO wireless device having a rank of 3 or 4.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 shows example DMRS ports for a typical 1+1 DMRS configuration;

FIG. 2 shows a schematic diagram of an example network architecture illustrating a communication system according to principles disclosed herein;

FIG. 3 shows a block diagram of a network node in communication with a wireless device over a wireless connection according to some embodiments of the present disclosure;

FIG. 4 shows a flowchart of an example process in a network node according to some embodiments of the present disclosure;

FIG. 5 shows a flowchart of an example process in a wireless device according to some embodiments of the present disclosure;

FIG. 6 shows a flowchart of another example process in a network node according to some embodiments of the present disclosure;

FIG. 7 shows an example network node in a MU-MIMO environment according to some embodiments of the present disclosure; FIG. 8 shows an example method of balancing groups and/or signaling ports and determining least redundant groups and/or signaling ports according to some embodiments of the present disclosure;

FIG. 9 shows an example diagram for signaling port selection according to some embodiments of the present disclosure;

FIG. 10 shows another example diagram for signaling port selection according to some embodiments of the present disclosure; and

FIG. 11 shows an example 0-RAN implementation for signaling port assignment (e.g., dynamic DMRS ports assignment) according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to determining (e.g., assigning) one or more signaling ports such as a DMRS ports such as a signaling port used to communicate with a wireless device. The determined signaling port may be used in MU-MIMO networks Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein can be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device etc.

Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

Further, any one of the network node and the WD (and/or any other device) may include one or more signaling ports which may be part of at least one of an antenna, antenna equipment, active antenna system (AAS), MU-MIMO, radio interface, communication interface, processing circuitry, and a standalone device. One or more signaling ports may be configured to communicate at least with another network node, a wireless device, and any other type of device. In addition, one or more signaling ports may be configured to transmit/receive any type of signal such as reference signals, including but not limited to reference signals (e.g., demodulation reference signal (DMRS), phase tracking reference signal (PTRS), sounding reference signal (SRS), channel state information reference signal (CSLRS)). The term “radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

The term balancing may refer to determining at least an occupancy (e.g., assignments such as possible assignments, existing assignments, potential assignments) associated with at least one group such as each multiplexing group (e.g., CDM groups) and/or at least one signaling port and/or any other parameter. Further, balancing may refer to as determining assignments that make occupancies (e.g., the number of occupancies) equal (or tending to equalize occupancies) across groups and/or signaling ports and/or other parameters.

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 2 a schematic diagram of a communication system 10 (e.g., MU-MIMO system, O-RAN, etc.), according to an embodiment, such as a 3 GPP-type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may include many more WDs 22 and network nodes 16.

Also, it is contemplated that a WD 22 can be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, WD 22 can be in communication with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN.

A network node 16 (eNB or gNB) is configured to include a node assignment unit 24 which is configured to perform any of the methods, process, steps, tasks, and features described herein, e.g., determine at least one of a first balancing of at least one multiplexing group and a second balancing of at least one signaling port associated with the WD based at least in part on the determined first balancing. A wireless device 22 is configured to include a WD assignment unit 26 which is configured to perform any of the methods, process, steps, tasks, and features described herein, e.g., determine a signal transmitted by the network node using at least one signaling port, the signal being based on at least one of a first balancing of at least one multiplexing group, a second balancing of the at least one signaling port, and a least redundancy of the at least one multiplexing group and the at least one signaling port. Example implementations, in accordance with an embodiment, of the WD 22 and network node 16 discussed in the preceding paragraphs will now be described with reference to FIG. 3.

The communication system 10 includes a network node 16 provided in a communication system 10 and including hardware 28 enabling it to communicate with the WD 22. The hardware 28 may include a radio interface 30 for setting up and maintaining at least a wireless connection 32 with a WD 22 located in a coverage area 18 served by the network node 16. The radio interface 30 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The radio interface 30 includes an array of antennas 34 to radiate and receive signal(s) carrying electromagnetic waves. Antennas 34 may include and/or refer to at least one signaling port as described herein.

In the embodiment shown, the hardware 28 of the network node 16 further includes processing circuitry 36. The processing circuitry 36 may include a processor 38 and a memory 40. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 36 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 38 may be configured to access (e.g., write to and/or read from) the memory 40, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node 16 further has software 42 stored internally in, for example, memory 40, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 42 may be executable by the processing circuitry 36. The processing circuitry 36 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16. Processor 38 corresponds to one or more processors 38 for performing network node 16 functions described herein. The memory 40 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 42 may include instructions that, when executed by the processor 38 and/or processing circuitry 36, causes the processor 38 and/or processing circuitry 36 to perform the processes described herein with respect to network node 16. For example, processing circuitry 36 of the network node 16 may include a node assignment unit 24 which is configured to perform any of the methods, process, steps, tasks, and features described herein, e.g., determine at least one of a first balancing of at least one multiplexing group and a second balancing of at least one signaling port associated with the WD based at least in part on the determined first balancing.

Further, network node 16 may include at least one distributed unit (DU) 60 and/or at least one radio unit (RU) 62. Any one of DU 60 and/or RU 62 may be configured to communicate with any one of the elements/components of communication system 10, e.g., of network node 16 and/or WD 22. Further, DU 60 may refer to any distributed unit such as NR DU, Open Radio Access Network ZORAN) DU, etc. Similarly, RU 62 may refer to any radio unit such as NR RU, O-RAN RU, etc. DU 60 may be configured to communicate with RU 62 on a lower layer split (LLS) such as LLS- User Plane (LLS-UP) and/or transmit/receive data (e.g., MU- MIMO data) which may include associated signaling ports (e.g., DMRS ports). DU 60 may also be configured to communicate with RU 62 on an LLS-CU and/or transmit/receive at least one PMI from/associated with WD 22. RU 62 may be configured to communicate with DU 60 on LLS such as LLS- UP and/or transmit/receive data (e.g., MU-MIMO data) which may include associated signaling ports (e.g., DMRS ports). RU 62 may also be configured to communicate with DU 60 on an LLS-CU and/or transmit/receive at least one PMI from/associated with WD 22. Network node 16 may also include at least one centralized unit (CU) configured to communicate with any one of the elements/components of communication system 10, e.g., of network node 16 and/or WD 22. In some embodiments, WD 22 may include (and/or perform the features of) at least one unit such as the DU 60, RU 62, and a CU.

The communication system 10 further includes the WD 22 already referred to. The WD 22 may have hardware 44 that may include a radio interface 46 configured to set up and maintain a wireless connection 32 with a network node 16 serving a coverage area 18 in which the WD 22 is currently located. The radio interface 46 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The radio interface 46 includes an array of antennas 48 to radiate and receive signal(s) carrying electromagnetic waves. Antennas 48 may include and/or refer to at least one signaling port as described herein.

The hardware 44 of the WD 22 further includes processing circuitry 50. The processing circuitry 50 may include a processor 52 and memory 54. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 50 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 52 may be configured to access (e.g., write to and/or read from) memory 54, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD 22 may further comprise software 56, which is stored in, for example, memory 54 at the WD 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD 22. The software 56 may be executable by the processing circuitry 50. The software 56 may include a client application 58. The client application 58 may be operable to provide a service to a human or non-human user via the WD 22.

The processing circuitry 50 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD 22. The processor 52 corresponds to one or more processors 52 for performing WD 22 functions described herein. The WD 22 includes memory 54 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 56 and/or the client application 58 may include instructions that, when executed by the processor 52 and/or processing circuitry 50, causes the processor 52 and/or processing circuitry 50 to perform the processes described herein with respect to WD 22. For example, the processing circuitry 50 of the wireless device 22 may include a WD assignment unit 26 which is configured to perform any of the methods, process, steps, tasks, and features described herein, e.g., determine a signal transmitted by the network node using at least one signaling port, the signal being based on at least one of a first balancing of at least one multiplexing group, a second balancing of the at least one signaling port, and a least redundancy of the at least one multiplexing group and the at least one signaling port.

In some embodiments, the inner workings of the network node 16 and WD 22 may be as shown in FIG. 3 and independently, the surrounding network topology may be that of FIG. 2.

The wireless connection 32 between the WD 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc. In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve.

Although FIGS. 2 and 3 show various “units” such as node assignment unit 24 and WD assignment unit 26 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 4 is a flowchart of an example process (i.e., method) in a network node 16. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the node assignment unit 24), processor 38, and/or radio interface 30. Network node 16 such as via processing circuitry 36 and/or processor 38 and/or radio interface 30 is configured to determine (Block S100) a first balancing of at least one multiplexing group and/or a second balancing of at least one signaling port associated with the WD 22 based at least in part on the determined first balancing. In some embodiments, at least one of: a least redundancy of the at least one multiplexing group and the at least one signaling port is determined based on at least one of the determined first balancing and second balancing; and a signal based on at least one of the first balancing, the second balancing, and the least redundancy is transmitted, the signal being transmitted to the WD 22 using the at least one signaling port.

In some other embodiments, determining the first balancing may include at least one of: receiving a WD list including a plurality of spatial locations associated at least with the WD; determining whether the at least one multiplexing group is balanced; and determining a least occupied multiplexing group from the at least one multiplexing group. Determining the second balancing may include determining a least occupied signaling port from the at least one signaling port based at least in part on the determined least occupied multiplexing group.

In one embodiment, the at least one multiplexing group may be at least one code division multiplexing, CDM, group; and the least one signaling port may be at least one DMRS port.

FIG. 5 is a flowchart of an example process in a wireless device 22 according to some embodiments of the present disclosure. One or more blocks described herein may be performed by one or more elements of wireless device 22 such as by one or more of processing circuitry 50 (including the WD assignment unit 26), processor 52, and/or radio interface 46. Wireless device 22 such as via processing circuitry 50 and/or processor 52 and/or radio interface 46 is configured to determine (Block S102) a signal transmitted by the network node 16 using at least one signaling port, the signal being based on at least one of a first balancing of at least one multiplexing group, a second balancing of the at least one signaling port, and a least redundancy of the at least one multiplexing group and the at least one signaling port.

In some embodiments, the first balancing may be based on least one of: a WD list including a plurality of spatial locations associated at least with the WD; whether the at least one multiplexing group is balanced; and a least occupied multiplexing group from the at least one multiplexing group; and the second balancing may be based on a least occupied signaling port of the at least one signaling port, the least occupied signaling port being based at least in part on the least occupied multiplexing group.

In some other embodiments, another signal including information associated a spatial location of the WD 22 is transmitted, the information being usable to determine the WD list.

In one embodiment, the at least one multiplexing group may be at least one code division multiplexing, CDM, group; and the least one signaling port may be at least one DMRS port.

FIG. 6 is a flowchart of another example process (i.e., method) in a network node 16. The network node may be in communication with a plurality of multipleinput multiple output (MIMO) wireless devices 22. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the node assignment unit 24), processor 38, and/or radio interface 30. Network node 16 is configured to determine (Block S104) an occupancy of a plurality of code division multiplexing, CDM, groups associated with the plurality of MU-MIMO wireless devices 22, as described herein. Network node 16 is configured to select (Block S106) a first CDM group of the plurality of CDM groups based on the first CDM group being a least occupied CDM group of the plurality of CDM groups, as described herein. Network node 16 is configured to determine (Block S108) an occupancy of demodulation reference signal, DMRS, ports for the first CDM group, as described herien. Network node 16 is configured to assign (Block S 110) at least one DMRS port associated with the first CDM group to a first MU-MIMO wireless device of the plurality of MU-MIMO wireless devices based on the occupancy of DMRS ports for the first CDM group where the first MU-MIMO wireless device has a rank of 1 or 2, as described herein. According to one or more embodiments of this aspect, the first CDM group is selected based on the first CDM group having fewer assigned DMRS ports than the remaining plurality of CDM groups.

According to one or more embodiments, the assignment of the at least one DMRS port associated with the first CDM group is based on the at least one DMRS port having fewer assignments than the remaining DMRS ports in the first CDM group. According to one or more embodiments, the selection of the first CDM group is based on a rank of the first MU-MIMO wireless device 22.

According to one or more embodiments, the first CDM group has a same occupancy as a second CDM group of the plurality of CDM groups, where the plurality of DMRS ports in the first CDM group have a same DMRS port occupancy, and the assignment of the at least one DMRS port associated with the first CDM group is based on a at least one previous DMRS port assignment.

According to one or more embodiments, the first CDM group is a least redundant of the plurality of CDM groups when the at least one previous DMRS port assignment is considered, and the at least one DMRS port associated with the first CDM group is a least redundant of the plurality of DMRS ports when the at least one previous DMRS port assignment is considered.

According to one or more embodiments, the processing circuitry 36 is further configured to cause transmission of DMRS in the at least one DMRS port associated with the first CDM group.

According to one or more embodiments, each of the plurality of MU-MIMO wireless devices 22 are selected for DMRS port assignment according to an ordering that is based on a spatial relationship of the plurality of MU-MIMO wireless devices 22.

According to one or more embodiments, the spatial relationships are based on at least one of: information included in channel state information, CSI, reports associated with the MU-MIMO wireless devices 22, and pairwise orthogonality of channel responses associated with the plurality of MU-MIMO wireless devices 22.

According to one or more embodiments, the processing circuitry 36 is further configured to assign at least one DMRS port to a second MU-MIMO wireless device 22 of the plurality of MU-MIMO wireless devices 22 based on: an updated occupancy of a plurality of CDM groups, an updated occupancy of DMRS ports for one of the plurality of CDM groups, and the updated occupancies being based on the at least one DMRS port assigned to the first MU-MIMO wireless device 22.

According to one or more embodiments, the processing circuitry 36 is further configured to assign predefined DMRS ports to a second MU-MIMO wireless device 22 of the plurality of MU- MIMO wireless devices 22 based on the second MU-MIMO wireless device 22 having a rank of 3 or 4.Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for to determining (e.g., assigning) one or more signaling ports such as a DMRS ports such as a signaling port used to communicate with a wireless device. As described below, a CDM group may refer to any group such as multiplexing group, and a DMRS port may refer to a signaling port.

FIG. 7 shows an example network node in a MU-MIMO environment. Within the MU-MIMO group, each WD 22 (e.g., WDs 22a, 22b, 22n) may be configured with different CSI-RS settings (e.g., N1,N2). In one example, network node 16, e.g., gNB, may be configured to establish a spatial relationship of WDs 22 within (and/or outside of) the MU-MIMO group based on the CSI reports sent by the WDs 22. In another example, the spatial relationship may be established based on the pairwise orthogonality from the channel responses between the WDs 22 in consideration.

In some embodiments, the spatial relationship is established. WDs 22 in the MU-MIMO group may be queued in an order from network node 16 (e.g., from a perspective of the network node) based on the spatial relationship. Based on the principle of balancing the multiplexing groups (e.g., CDM groups and/or the signaling ports (e.g., DMRS ports) occupied, network node 16 may be configured to assign limited signaling ports (e.g., DMRS ports) such that WDs 22 occupy signaling ports (e.g., DMRS ports) that are interfered less than a predetermined amount (e.g., as little as possible to achieve a predetermined performance).

FIG. 8 shows an example method of balancing groups and/or signaling ports and determining least redundant groups and/or signaling ports according to some embodiments of the present disclosure. An input may be a list of WDs 22 (e.g., a sorted list) with respect to spatial locations. In one nonlimiting example, a spatial relationship for MU-MIMO WDs 22 is assumed to established. Based on one or more configurations (e.g., DMRS configurations), network node 16 may be configured to determine (e.g., arrive at) the following conditions for assigning one or more signaling ports (DMRS ports) for each WD 22: available signaling ports (DMRS ports); and quantity/number of multiplexing groups (e.g., CDM groups). In addition, available options (e.g., such as options listed in Table 7.3.1.2.2-1 to Table 7.3.1.2.2-4 described in 3GPP Technical Specification (TS) 38.212 V15.12.0) may be restricted as a condition for DMRS assignment (i.e., signaling port assignment). That is, network node 16 may be configured to determine available signaling port assignments (e.g., DMRS assignments) based on:

• Per-rank DMRS port(s) assignment (or equivalently, the field “Antenna port(s)” from DCI 1_1)

For example, available choices for rank-2 DMRS assignment may include (0,1), (2,3), and (0,2) which corresponds to a “value” field from a table as 7, 8, and 11, respectively. However, network node 16 may be configured (e.g., for performance or implementation considerations) to restrict available rank-2 DMRS assignment to include (0,1) and (2,3), but not (0,2).

Weights (and/or a number of occupancies) of each signaling port (e.g., DMRS port) may be re-initialized to a predetermined value (e.g., 0) with respect to a time interval (e.g., at the beginning of each TTI). For DMRS assignment of each WD, network node 16 may be configured to perform at least one of the steps shown in FIG. 8 and/or assign DMRS port(s) based on options listed in a table (e.g., Table 7.3.1.2.2-1 to Table 7.3.1.2.2-4 in 3GPP Technical Specification (TS) 38.212 V15.12.0) and WD rank. Network node 16 may be configured to select a least one signaling port (e.g., DMRS port). The selected signaling may be recorded accordingly for the next DMRS assignment (e.g., associated with a WD 22) such as until all WDs have been considered. More specifically:

Step 200: Determine (e.g., check and/or apply) balancing of CDM groups.

Network node 16 may be configured to determine (e.g., first check) whether the CDM groups are balanced or not, and then choose the CDM group that is the least occupied (e.g., if applicable). When there are more than one CDM group that are least occupied, then network node 16 may determine (e.g., choose) one that is first available. “Balancing of CDM groups” may refer to determining whether the number of occupancies for the CDM groups in consideration are the same (and/or performing one or more steps to make the same). In one example, there are two CDM groups in total based on the given DMRS configurations, namely, CDM group 0 (e.g., DMRS ports 0,1) and CDM group 1 (e.g., DMRS ports 2,3). Assuming previous DMRS assignments for the MU-MIMO WDs in consideration have taken DMRS ports 0 and 1 once each, and DMRS port 2 once. Then the CDM group 0 has a total weight of 2, and the CDM group 1 has a total wright of 1. For the current WD 22 in consideration, if the WD 22 has either rank-2 or rank-1, then the DMRS assignment of the WD 22 may be taken from the least occupied CDM group, e.g., CDM group 1 in this case. If the WD 22 has either rank-3 or rank-4, network node 16 may be configured to skip balancing of CDM groups (e.g., becomes irrelevant), and DMRS ports may be assigned as (0-2) and (0-3), respectively. For example, for rank-3 and/or rank-4 the DMRS ports may be predefined or preconfigured for the respective rank.

Step 202: Determine (e.g., check and/or apply) balancing of DMRS ports from the least occupied CDM group from Step 200.

Following the previous example, if the WD 22 has rank-1, then DMRS ports are chosen from the least CDM group, which is the CDM group 1. From CDM group 1, DMRS port 2 has been taken at least once before, but DMRS port 3 has not been taken. Therefore, the DMRS port assignment will be taken from the least occupied DMRS port from the least occupied CDM group, which is DMRS port 3 in this nonlimiting example. “Balancing of DMRS ports” may refer to determining whether the number of occupancies for the DMRS ports in consideration are the same (and/or performing one or more steps to make the same).

Step 204: Determine (e.g., apply) the least redundant CDM group and DMRS port(s), e.g., by referring to the previous DMRS ports assignment such as if there is a tie following steps S200 and S202. In some embodiments, step 204 may be performed even if there is not tie. In cases (e.g., from both steps S200 and S202) where CDM groups and DMRS ports are balanced, the DMRS assignment may be chosen based on the least redundant CDM groups and/or DMRS ports such as by referring to the previous DMRS assignment. For example, if there is a tie (i.e., CDM groups and DMRS ports are balanced) and the previous DMRS ports are from the second CDM group, then the new DMRS ports may be assigned from the first CDM group (i.e., the least redundant to the previous assignment, and the same for the notion for DMRS ports within the CDM group). In another example, if there is a tie (i.e., CDM groups and DMRS ports are balanced) and the previous DMRS ports are from the first CDM group, then the new DMRS ports may not be assigned from the first CDM group (i.e., these are not the least redundant to the previous assignment, and the same for the notion for DMRS ports within the CDM group).

Although steps S200-S204 are shown in a particular order, it is noted that the network node 16 may be configured to perform at least one of steps S200-S204 in any order or not perform any of these steps. In other words, the order of the steps shown is not required and not all steps are required to be performed.

In one example, some WDs 22 have been assigned DMRS ports already, and currently each DMRS port has a total weight of 2, or equivalently each CDM group has a total weight of 4. Assuming that WD 22 in consideration has rank-2 to be assigned for the DMRS ports, network node 16 may be configured to resort to (i.e., perform) S204 since there is a tie from both S200 and S202. If the previous WD 22 has a rank-2 taking DMRS ports (0,1), then the current rank-2 WD may take DMRS ports (2,3) to avoid re-assigning the DMRS ports (0,1) again immediately following the previous WD DMRS assignment. If the previous WD 22 has rank-1 taking DMRS ports 0, then the current rank-2 WD 22 may also take DMRS ports (2,3) such as to avoid re-assigning the DMRS ports from the same CDM group again, e.g., immediately following the previous WD DMRS assignment.

Following nonlimiting pseudo code describes in further detail how network node may be configured to assign the DMRS ports in the ordered MU-MIMO group, from the first WD 22 until the last WD 22. However, the network node is not limited to being configured to include the nonlimiting pseudo code and may be configured in any other way. Specifically, the example is based on the “1+1” DMRS configuration. There are up to four DMRS ports available (or equivalently 2 CDM groups) in total for the MU-MIMO group in consideration. Available per-rank DMRS port(s) assignment may be in any way including as listed below:

• DMRS port 0, 1, 2, or 3 for 1-layer transmissions;

• DMRS ports (0,1) or (2,3) for 2-layer transmissions;

• DMRS ports (0-2) for 3-layer transmissions; and

• DMRS ports (0-3) for 4-layer transmissions.

Nonlimiting example of pseudo code (UE as used in the pseudo code may refer to WD)

Switch (number of layer transmission for the WD 22 in consideration) {

Case 1

If (ueDmrsPortAlloc[0] + ueDmrsPortAlloc[l]) < (ueDmrsPortAlloc[2] + ueDmrsPortAlloc[3]) // First CDM group has lower weights

Select either port 0 or 1 whichever is least occupied // Select port 0 if equally occupied

Add 1 to either ueDmrsPortAlloc[0] or ueDmrsPortAlloc[l] accordingly

Elseif (ueDmrsPortAlloc[0] + ueDmrsPortAlloc[l]) > (ueDmrsPortAlloc[2] + ueDmrsPortAlloc[3]) // Second CDM group has lower weights

Select either port 2 or port 3 whichever is least occupied // Select port 2 if equally occupied

Add 1 to either ueDmrsPortAlloc[2] or ueDmrsPortAlloc[3] accordingly

Else // Two CDM groups have same weights

If this is the first WD or the previous WD selects more ports from the second than from the first CDM group

Select either port 0 or 1 whichever is least occupied // Select port 0 if equally occupied

Add 1 to either ueDmrsPortAlloc[0] or ueDmrsPortAlloc[l] accordingly Else // This case includes the previous WD is rank 3 or 4

Select either port 2 or 3 whichever is least occupied //

Select port [2] if equally occupied

Add 1 to either ueDmrsPortAlloc[2] or ueDmrsPortAlloc[3] accordingly

End

End

Case 2

If (ueDmrsPortAlloc[0] + ueDmrsPortAlloc[l]) < (ueDmrsPortAlloc[2] + ueDmrsPortAlloc[3]) // First CDM group has lower weights

Select ports 0,1

Add 1 to ueDmrsPortAlloc[0] and ueDmrsPortAlloc[l]

Elseif (ueDmrsPortAlloc[0] + ueDmrsPortAlloc[l]) > (ueDmrsPortAlloc[2] + ueDmrsPortAlloc[3]) // Second CDM group has lower weights

Select ports 2,3

Add 1 to ueDmrsPortAlloc[2] and ueDmrsPortAlloc[3]

Else // Two CDM groups have the same weights

If this is the first WD or the previous WD selects more ports from the second than from the first CDM group

Select ports 0,1

Add 1 to ueDmrsPortAlloc[0] and ueDmrsPortAlloc[l]

Else // This case includes the previous WD is rank 3 or 4

Select ports 2,3

Add 1 to ueDmrsPortAlloc[2] and ueDmrsPortAlloc[3]

End

End

Case 3

Select ports 0,1,2

Add 1 to ueDmrsPortAlloc[0], ueDmrsPortAlloc[l], and ueDmrsPort Alloc [2] Case 4

Select ports 0, 1,2,3

Add 1 to ueDmrsPortAlloc[0], ueDmrsPortAlloc[l], ueDmrsPortAlloc[2], and ueDmrsPortAlloc[3]

}

In the above, ueDmrsPortAlloc[0], ueDmrsPortAlloc[l], ueDmrsPortAlloc[2], and ueDmrsPortAlloc[3] are for the purpose of checking whether DMRS ports and two CDM groups are balanced or not for the next port assignments. The initial value of those variables may be 0 and/or re-initialized per TTI.

Nonlimiting example

In some embodiments (e.g., field trial to measure radio access technology (RAT) MU-MIMO total throughput), the spatial relationship of four MU-MIMO WDs 22 in consideration are established by the order of WDO, WD1, WD2, and WD3. The DMRS configuration is “1+1” and WDs 22 are all with 2-layer DL transmissions. In addition, network node 16 may be configured to consider (e.g., only) DMRS ports (0,1) and (2,3) for 2-layer transmissions.

FIGS. 9 and 10 show diagrams (e.g., a Trellis diagram) of DMRS ports assignments (e.g., all possible DMRS ports assignments) for four WDs 22 from the corresponding rank combinations, according to the principles of the present disclosure such as the principle of CDM groups and DMRS ports.

In one example, the ranks of (WDO, WD1, WD2, WD3) are given as (1, 1, 1, 1). DMRS ports corresponding to WD0-WD3 may be given as [0], [2], [1], [3], which is the top branch of FIG. 9. In another example, assume the ranks of (WDO, WD1, WD2, WD3) are given as (2, 2, 2, 2). DMRS ports corresponding to WD0-WD3 may be given as [0 1], [2 3], [0 1], [2 3], which is the bottom branch from FIG. 10. WDO, WD1, WD2, WD3 may refer to WDs 22a, 22b, 22c, 22d.

DMRS ports selection (i.e., determination) for downlink (DL) MU-MIMO may be implemented in 0-RAN, e.g., 0-DU in ORAN architecture as shown in FIG. 11. One DU 60 and a first RU 62a and a second RU 62b (collectively RU 62) are shown but the principles described in the present disclosure are not limited to the configuration shown in FIG. 11. In one example, PMI’s from WDs 22 may be indicated from any one of RUs 62a, 62b to DU 60 per (and/or included in a) CSI report. In another example, the PMI information and/or other similar measure such as pairwise orthogonality check for channel correlation (e.g., for the purpose of dynamic DMRS ports selection) may be decoded in DU 60 (e.g., 0-DU). For each DL transmission per slot, PDSCH from MU-MIMO WDs 22 with the associated DMRS ports are sent from DU 60 (e.g., 0-DU) to any one of RU 62a, 62b (e.g., first and second O-RUs). Note that PDSCH and PDSCH DMRS may be applied to the same precoding. Any RU 62 may be of any category. For example, both 0-RU Category A (Non-precoding 0-RAN Radio Unit) and Category B (Precoding 0-RAN Radio Unit) may be applicable. In one example, the main difference lies in whether LLS-U carries beamformed or non-beamformed PDSCH and PDSCH DMRS.

Addition Nonlimiting Examples

Example Al. A network node 16 configured to communicate at least with a wireless device 22, WD 22, the network node 16 configured to, and/or comprising a radio interface 30 and/or comprising processing circuitry 36 configured to: determine a first balancing of at least one multiplexing group and/or a second balancing of at least one signaling port associated with the WD 22 based at least in part on the determined first balancing.

Example A2. The network node 16 of Example Al, wherein at least one of the network node 16, the radio interface 30, the processing circuitry 36 is further configured to at least one of: determine a least redundancy of the at least one multiplexing group and the at least one signaling port based on at least one of the determined first balancing and second balancing; and cause the network node 16 to transmit a signal based on at least one of the first balancing, the second balancing, and the least redundancy, the signal being transmitted to the WD 22 using the at least one signaling port.

Example A3. The network node of any one of Examples Al and A2, wherein at least one of: determining the first balancing includes at least one of: receiving a WD list including a plurality of spatial locations associated at least with the WD 22; determining whether the at least one multiplexing group is balanced; and determining a least occupied multiplexing group from the at least one multiplexing group; and determining the second balancing includes determining a least occupied signaling port from the at least one signaling port based at least in part on the determined least occupied multiplexing group.

Example A4. The network node 16 of any one of Examples A1-A3, wherein at least one of: the at least one multiplexing group is at least one code division multiplexing, CDM, group; and the least one signaling port is at least one DMRS port.

Example Bl. A method implemented in a network node 16 configured to communicate at least with a wireless device, WD 22, the method comprising: determining a first balancing of at least one multiplexing group and/or a second balancing of at least one signaling port associated with the WD 22 based at least in part on the determined first balancing.

Example B2. The method of Example Bl, wherein the method further includes at least one of: determining a least redundancy of the at least one multiplexing group and the at least one signaling port based on at least one of the determined first balancing and second balancing; and transmitting a signal based on at least one of the first balancing, the second balancing, and the least redundancy, the signal being transmitted to the WD 22 using the at least one signaling port.

Example B3. The method of any one of Examples Bl and B2, wherein at least one of: determining the first balancing includes at least one of: receiving a WD list including a plurality of spatial locations associated at least with the WD 22; determining whether the at least one multiplexing group is balanced; and determining a least occupied multiplexing group from the at least one multiplexing group; and determining the second balancing includes determining a least occupied signaling port from the at least one signaling port based at least in part on the determined least occupied multiplexing group.

Example B4. The method of any one of Examples B 1-B3, wherein at least one of: the at least one multiplexing group is at least one code division multiplexing, CDM, group; and the least one signaling port is at least one DMRS port.

Example Cl. A wireless device, WD 22, configured to communicate with a network node 16, the WD 22 configured to, and/or comprising a radio interface and/or processing circuitry 50 configured to: determine a signal transmitted by the network node 16 using at least one signaling port, the signal being based on at least one of a first balancing of at least one multiplexing group, a second balancing of the at least one signaling port, and a least redundancy of the at least one multiplexing group and the at least one signaling port.

Example C2. The WD 22 of Example Cl, wherein at least one of: the first balancing is based on least one of: a WD list including a plurality of spatial locations associated at least with the WD 22; whether the at least one multiplexing group is balanced; and a least occupied multiplexing group from the at least one multiplexing group; and the second balancing is based on a least occupied signaling port of the at least one signaling port, the least occupied signaling port being based at least in part on the least occupied multiplexing group.

Example C3. The WD 22 of Example C2, wherein the processing circuitry 50 is further configured to: cause the WD 22 to transmit another signal including information associated a spatial location of the WD 22, the information being usable to determine the WD list. Example C4. The WD 22 of any one of Examples C1-C3, wherein at least one of: the at least one multiplexing group is at least one code division multiplexing, CDM, group; and the least one signaling port is at least one DMRS port.

Example DI. A method implemented in a wireless device, WD 22, configured to communicate with a network nodel6, the method comprising: determining a signal transmitted by the network node 16 using at least one signaling port, the signal being based on at least one of a first balancing of at least one multiplexing group, a second balancing of the at least one signaling port, and a least redundancy of the at least one multiplexing group and the at least one signaling port.

Example D2. The method of Example DI, wherein at least one of: the first balancing is based on least one of: a WD list including a plurality of spatial locations associated at least with the WD 22; whether the at least one multiplexing group is balanced; and a least occupied multiplexing group from the at least one multiplexing group; and the second balancing is based on a least occupied signaling port of the at least one signaling port, the least occupied signaling port being based at least in part on the least occupied multiplexing group.

Example D3. The method of Example D2, wherein the method further includes: transmitting another signal including information associated a spatial location of the WD 22, the information being usable to determine the WD list.

Example D4. The method of any one of Examples D1-D3, wherein at least one of: the at least one multiplexing group is at least one code division multiplexing, CDM, group; and the least one signaling port is at least one DMRS port.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination. Abbreviations that may be used in the preceding description include:

AAS Active Antenna System

CSI-RS Channel State Information Reference Signal

DFT Discrete Fourier Transform DMRS Demodulation reference Signal

MIMO Multiple-Input Multiple- Output

MU Multiple Users

O-DU O-RAN Distributed Unit

O-RU O-RAN Radio Unit ORAN Open RAN

PMI Precoding Matrix Indicator

PMID Precoding Matrix Indicator (PMI) Distance

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.