Discovery of ranks for communication channels

Abstract

An apparatus comprises means for determining joint rank information associated with a combined channel using a plurality of received reference signals, the plurality of received reference signals being received from an access point, the plurality of reference signals being transmitted through different subsets of antenna ports of the access point, the different subsets of antenna ports use different resources for transmitting the reference signals, and the combined channel is the result of the joint of the antenna ports of each different subset of antenna ports of the access point with respective channels between the antenna ports that receive the plurality of reference signals. The apparatus further comprises means for causing information to be sent to an access point related to the determination of joint rank information associated with the combined channel.

Description

Technical Field

[0001] The examples described herein generally relate to apparatus, methods, and computer programs, and more particularly (but not exclusively) to apparatus, methods, and computer programs related to reference signals. Background Art

[0002] A communication system can be viewed as a facility that enables communication sessions between two or more entities (e.g., communication devices, base stations, and / or other nodes) by providing a carrier between the various entities involved in the communication path.

[0003] The communication system may be a wireless communication system. Examples of wireless systems include public land mobile networks (PLMNs) operating based on radio standards such as those provided by 3GPP, satellite-based communication systems, and various wireless local area networks such as wireless local area networks (WLANs). Wireless systems can typically be divided into cells and are therefore often referred to as cellular systems.

[0004] Communication systems and associated devices typically operate with reference to a given standard or specification, which sets out what the various entities associated with the system are allowed to do and how it should be implemented. The communication protocols and / or parameters that should be used for the connection are also typically defined. An example of a standard is the so-called 5G standard. Summary of the Invention

[0005] According to an aspect, an apparatus is provided, comprising: a component for determining joint rank information associated with a combined channel using multiple received reference signals, the multiple received reference signals being received from an access point, the multiple reference signals being sent through different subsets of antenna ports of the access point, the different subsets of antenna ports using different resources for sending the reference signals, the combined channel being the result of a union of respective channels between antenna ports of each different subset of antenna ports of the access point and the antenna ports receiving the multiple reference signals; and a component for causing information to be sent to the access point related to the determination of the joint rank information, the joint rank information being associated with the combined channel.

[0006] The apparatus may include means for receiving multiple reference signals from an access point, the reference signals transmitted over different subsets of the access point's antenna ports.

[0007] A first subset of the plurality of reference signals may be sent through a first subset of antennas and a second subset of the plurality of reference signals may be sent through a second subset of antenna ports.

[0008] A first subset of the multiple reference signals may be sent over a first subset of antenna ports using one or more time resources different from time resources used to send a second subset of the multiple reference signals over a second subset of antenna ports.

[0009] Reference signals may be transmitted such that a first subset of multiple reference signals is transmitted through a first subset of antenna ports in a first time slot, and a second subset of multiple reference signals is transmitted through a second subset of antenna ports in a subsequent second time slot.

[0010] The access point may include multiple transmission and reception points, one subset of the different subsets of antenna ports is associated with one of the multiple transmission and reception points, and another subset of the different subsets of antenna ports is associated with another transmission and reception point of the multiple transmission and reception points.

[0011] The apparatus may include: a component for causing information to be sent to an access point, the information indicating to the access point: the apparatus is capable of supporting the use of reference signals sent by different subsets of the access point's antenna ports using different resources to determine joint rank information between the access point's antenna ports and the apparatus associated with a combined channel.

[0012] The apparatus may comprise means for performing measurements relative to a received reference signal.

[0013] The apparatus may include antenna ports, a common set of antenna ports configured to receive a plurality of reference signals.

[0014] The common set of antenna ports includes all antenna ports of the device.

[0015] The common set of antenna ports may include four antenna ports.

[0016] The number of antenna ports in the common set of antenna ports may be equal to the number of antenna ports of the access point used to transmit the multiple reference signals.

[0017] The means for using the received plurality of reference signals may be configured for reconstructing a combined channel matrix comprising channel coefficients representing the combined channel.

[0018] The means for using the received plurality of reference signals may be configured for reconstructing a combined channel matrix from the individual channel matrices, the combined channel matrix comprising channel coefficients representing the combined channel.

[0019] The information sent to the access node may include information regarding one or more reference signal indices associated with one or more of the plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0020] The means for determining joint rank information using the received multiple reference signals may be used to determine whether the combined channel can achieve the target rank.

[0021] The target rank can be 4.

[0022] The reference signal may include a channel state information reference signal and / or a synchronization signal block.

[0023] Each different subset of antenna ports may include two antenna ports.

[0024] The number of different subsets of antenna ports may be two.

[0025] Devices and access points may operate in frequency range 2.

[0026] The apparatus may be in or may be provided in a communication device.

[0027] According to another aspect, a device is provided, comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least: determine joint rank information associated with a combined channel using multiple received reference signals, wherein the multiple received reference signals are received from an access point, the multiple reference signals are sent through different subsets of antenna ports of the access point, the different subsets of antenna ports use different resources for sending reference signals, and the combined channel is between antenna ports of different subsets of antenna ports of the access point and the antenna port that receives the multiple reference signals; and cause information to be sent to the access point related to the determination of the joint rank information, wherein the joint rank information is associated with the combined channel.

[0028] An apparatus may be caused to receive multiple reference signals from an access point, the reference signals being transmitted through different subsets of the access point's antenna ports.

[0029] A first subset of the plurality of reference signals may be sent through a first subset of antennas, and a second subset of the plurality of reference signals may be sent through a second subset of antenna ports.

[0030] A first subset of the multiple reference signals may be sent over a first subset of antenna ports using one or more time resources different from time resources used to send a second subset of the multiple reference signals over a second subset of antenna ports.

[0031] Reference signals may be transmitted such that a first subset of multiple reference signals is transmitted through a first subset of antenna ports in a first time slot, and a second subset of multiple reference signals is transmitted through a second subset of antenna ports in a subsequent second time slot.

[0032] The access point may include multiple transmit-receive points, one subset of the different subsets of antenna ports is associated with one of the multiple transmit-receive points, and another subset of the different subsets of antenna ports is associated with another transmit-receive point of the multiple transmit-receive points.

[0033] The apparatus may be caused to cause information to be sent to an access point indicating to the access point that the apparatus is capable of supporting determination of joint rank information between the access point's antenna ports and the apparatus associated with a combined channel using reference signals sent by different subsets of the access point's antenna ports using different resources.

[0034] The apparatus may be caused to perform measurements relative to a received reference signal.

[0035] The apparatus may include antenna ports, and the method may include receiving a plurality of reference signals at a common set of antenna ports.

[0036] The common set of antenna ports may include all antenna ports of the device.

[0037] The common set of antenna ports may include four antenna ports.

[0038] The number of antenna ports in the common set of antenna ports may be equal to the number of antenna ports of the access point used to transmit the multiple reference signals.

[0039] The apparatus may be caused to use the received plurality of reference signals for reconstructing a combined channel matrix comprising channel coefficients representing the combined channel.

[0040] The apparatus may be caused to use the received multiple reference signals for reconstructing a combined channel matrix from the respective channel matrices, the channel matrix including channel coefficients representing the combined channel.

[0041] The information sent to the access node may include information regarding one or more reference signal indices associated with one or more of the plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0042] The apparatus may be caused to use the received multiple reference signals to determine whether the combined channel can achieve the target rank.

[0043] The target rank can be 4.

[0044] The reference signal may include a channel state information reference signal and / or a synchronization block.

[0045] Each different subset of antenna ports may include two antenna ports.

[0046] The number of different subsets of antenna ports may be two.

[0047] Devices and access points may operate in frequency range 2.

[0048] The apparatus may be in or may be provided in a communication device.

[0049] According to another aspect, a method is provided, comprising: determining joint rank information associated with a combined channel using multiple received reference signals, the multiple received reference signals being received from an access point, the multiple reference signals being sent through different subsets of antenna ports of the access point, the different subsets of antenna ports using different resources for sending the reference signals, the combined channel being between antenna ports of the different subsets of antenna ports of the access point and the antenna port receiving the multiple reference signals; and causing information to be sent to the access point related to the determination of the joint rank information, the joint rank information being associated with the combined channel.

[0050] The method may include receiving a plurality of reference signals from an access point, the reference signals being transmitted over different subsets of antenna ports of the access point.

[0051] A first subset of the plurality of reference signals may be sent through a first subset of antennas, and a second subset of the plurality of reference signals may be sent through a second subset of antenna ports.

[0052] A first subset of the multiple reference signals may be sent over a first subset of antenna ports using one or more time resources different from time resources used to send a second subset of the multiple reference signals over a second subset of antenna ports.

[0053] Reference signals may be transmitted such that a first subset of multiple reference signals is transmitted through a first subset of antenna ports in a first time slot, and a second subset of multiple reference signals is transmitted through a second subset of antenna ports in a subsequent second time slot.

[0054] The access point may include multiple transmit and receive points, one subset of the different subsets of antenna ports is associated with one of the multiple transmit and receive points, and another subset of the different subsets of antenna ports is associated with another of the multiple transmit and receive points.

[0055] The method may include causing information to be sent to an access point, the information indicating to the access node that the device is capable of supporting determining joint rank information between the access point's antenna ports and the device associated with a combined channel using reference signals sent by different subsets of the access point's antenna ports using different resources.

[0056] The method may include performing measurements relative to a received reference signal.

[0057] The apparatus may include antenna ports, and the method may include receiving a plurality of reference signals at a common set of antenna ports.

[0058] The common set of antenna ports may include all antenna ports of the device.

[0059] The common set of antenna ports may include four antenna ports.

[0060] The number of antenna ports in the common set of antenna ports may be equal to the number of antenna ports of the access point used to transmit the multiple reference signals.

[0061] The method may include using the received plurality of reference signals for reconstructing a combined channel matrix including channel coefficients representing the combined channel.

[0062] The method may include using the received plurality of reference signals for reconstructing a combined channel matrix from the respective channel matrices, the channel matrix including channel coefficients representing the combined channel.

[0063] The information sent to the access node may include information regarding one or more reference signal indices associated with one or more of the plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0064] The method may include using the received plurality of reference signals to determine whether the combined channel can achieve a target rank.

[0065] The target rank can be 4.

[0066] The reference signal may include a channel state information reference signal and / or a synchronization block.

[0067] Each different subset of antenna ports may include two antenna ports.

[0068] The number of different subsets of antenna ports may be two.

[0069] Devices and access points may operate in frequency range 2.

[0070] The method may be performed by an apparatus. The apparatus may be in a communication device or may be provided in the communication device.

[0071] According to another aspect, an apparatus is provided, comprising: a component for causing multiple reference signals to be sent to a communication device, the multiple reference signals being sent through different subsets of antenna ports of an access point, the different subsets of antenna ports using different resources for sending the reference signals; and a component for receiving joint rank information from the communication device, the joint rank information relating to a combined channel between antenna ports of the different subsets of antenna ports of the access point and the antenna port of the communication device receiving the multiple reference signals.

[0072] The means for causing may be configured to cause a first subset of the plurality of reference signals to be transmitted through a first subset of antenna ports and to cause a second subset of the plurality of reference signals to be transmitted through a second subset of antenna ports.

[0073] The means for causing may cause a first subset of the plurality of reference signals to be transmitted through a first subset of antenna ports using one or more time resources different from time resources used to transmit a second subset of the plurality of reference signals through a second subset of antenna ports.

[0074] The means for causing may cause a first subset of the plurality of reference signals to be transmitted through a first subset of antenna ports in a first intermediate time slot and cause a second subset of the plurality of reference signals to be transmitted through a second subset of antenna ports in a subsequent second time slot.

[0075] The access point may include multiple transmission and reception points, one subset of the different subsets of antenna ports is associated with one of the multiple transmission and reception points, and another subset of the different subsets of antenna ports is associated with another transmission and reception point of the multiple transmission and reception points.

[0076] The apparatus may include a component for receiving information from a communication device, the information indicating that the communication device is capable of supporting the use of reference signals transmitted by different subsets of antenna ports of an access point using different resources to determine joint rank information associated with a combined channel between the antenna ports of the access point and the communication device.

[0077] The received joint rank information includes information regarding one or more reference signal indices associated with one or more reference signals in a plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0078] The reference signal may include a channel state information reference signal and / or a synchronization block.

[0079] Each different subset of antenna ports may include two antenna ports.

[0080] The number of different subsets of antenna ports may be two.

[0081] Communication equipment and devices may operate in frequency range 2.

[0082] The apparatus may be in or may be provided in an access node (may also be referred to as an access point).

[0083] According to another aspect, an apparatus is provided, comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, causes the apparatus to at least: cause multiple reference signals to be transmitted to a communication device, the multiple reference signals being transmitted through different subsets of antenna ports of an access point, the different subsets of antenna ports using different resources for transmitting the reference signals; and receive joint rank information from the communication device, the joint rank information relating to a combined channel between antenna ports of the different subsets of antenna ports of the access point and the antenna port of the communication device receiving the multiple reference signals.

[0084] The apparatus may be caused to cause a first subset of the plurality of reference signals to be transmitted through a first subset of antenna ports and to cause a second subset of the reference signals to be transmitted through a second subset of antenna ports.

[0085] The apparatus may be caused to cause a first subset of multiple reference signals to be transmitted over a first subset of antenna ports using one or more time resources different from time resources used to transmit a second subset of multiple reference signals over a second subset of antenna ports.

[0086] The apparatus may be caused to cause a first subset of the plurality of reference signals to be transmitted through a first subset of antenna ports in a first time slot and to cause a second subset of the plurality of reference signals to be transmitted through a second subset of antenna ports in a subsequent second time slot.

[0087] The access point may include multiple transmission and reception points, one subset of the different subsets of antenna ports is associated with one of the multiple transmission and reception points, and another subset of the different subsets of antenna ports is associated with another transmission and reception point of the multiple transmission and reception points.

[0088] An apparatus may be caused to receive information from a communications device indicating that the communications device is capable of supporting determination of joint rank information between the antenna ports of an access point and the communications device associated with a combined channel by using reference signals transmitted by different subsets of the antenna ports of the access point using different resources.

[0089] The received rank information may include information regarding one or more reference signal indices associated with one or more reference signals in a plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0090] The reference signal may include a channel state information reference signal and / or a synchronization block.

[0091] Each different subset of antenna ports may include two antenna ports.

[0092] The number of different subsets of antenna ports may be two.

[0093] Communication equipment and devices may operate in frequency range 2.

[0094] The apparatus may be in or may be provided in an access node (may also be referred to as an access point).

[0095] According to another aspect, a method is provided, comprising causing multiple reference signals to be sent to a communication device, the multiple reference signals being sent through different subsets of antenna ports of an access point, the different subsets of antenna ports using different resources for sending the reference signals; and receiving joint rank information from the communication device, the joint rank information relating to a combined channel between antenna ports of the different subsets of antenna ports of the access point and an antenna port of the communication device receiving the multiple reference signals.

[0096] The method may include causing a first subset of a plurality of reference signals to be transmitted through a first subset of antenna ports, and causing a second subset of the plurality of reference signals to be transmitted through a second subset of antenna ports.

[0097] The method may include causing a first subset of multiple reference signals to be transmitted through a first subset of antenna ports using one or more time resources different than time resources used to transmit a second subset of multiple reference signals through a second subset of antenna ports.

[0098] The method includes causing a first subset of a plurality of reference signals to be transmitted through a first subset of antenna ports in a first time slot, and causing a second subset of the plurality of reference signals to be transmitted through a second subset of antenna ports in a subsequent second time slot.

[0099] The access point may include multiple transmission and reception points, one subset of the different subsets of antenna ports is associated with one of the multiple transmission and reception points, and another subset of the different subsets of antenna ports is associated with another transmission and reception point of the multiple transmission and reception points.

[0100] The method may include receiving information from a communications device indicating that the communications device is capable of supporting determining joint rank information between the access point's antenna ports and the communications device associated with a combined channel using reference signals transmitted via different subsets of the access point's antenna ports using different resources.

[0101] The received rank information may include information regarding one or more reference signal indices associated with one or more reference signals in a plurality of reference signals transmitted via a corresponding subset of antenna ports of the access point.

[0102] The reference signal may include a channel state information reference signal and / or a synchronization block.

[0103] Each different subset of antenna ports may include two antenna ports.

[0104] The number of different subsets of antenna ports may be two.

[0105] Communication devices and access points may operate in frequency range 2.

[0106] The method may be performed by an apparatus. The apparatus may be in an access node or may be provided in an access node.

[0107] According to a further aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform any of the methods described hereinbefore.

[0108] According to a further aspect, there is provided a computer program comprising instructions which, when executed, cause any of the methods described hereinbefore to be performed.

[0109] According to an aspect, there is provided a computer program comprising computer executable code which when enabled causes any of the methods described hereinbefore to be performed.

[0110] According to an aspect, a computer-readable medium is provided, comprising program instructions stored thereon for performing at least one of the above methods.

[0111] According to an aspect, there is provided a non-transitory computer-readable medium comprising program instructions, which, when executed by an apparatus, causes the apparatus to perform any of the methods described above.

[0112] According to an aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed, cause any of the methods described above to be performed.

[0113] According to an aspect, a non-volatile memory medium is provided, comprising program instructions stored thereon for executing at least one of the above methods.

[0114] In the above, a number of different aspects have been described. It should be understood that further aspects may be provided by combining any two or more of the above-described aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Some examples will now be described in more detail, by way of illustration only, with reference to the accompanying drawings, in which:

[0116] Figure 1 An example of a system that may provide some embodiments is shown;

[0117] Figure 2 A schematic diagram illustrating a control device according to some example embodiments;

[0118] Figure 3 Schematically illustrating antenna ports at an access node and at a communication device;

[0119] Figure 4a and 4b Schematic diagram showing different examples of locations of antenna panels on a communication device;

[0120] Figure 5 shows the signal flow of some embodiments;

[0121] Figure 6 An example with two transmitting and receiving points is shown;

[0122] Figure 7 The methods of some embodiments are illustrated; and

[0123] FIG8 illustrates another method of some embodiments. DETAILED DESCRIPTION

[0124] The following description provides exemplary descriptions of some embodiments. Although the specification may use "one," "an," or "some" examples or embodiments at some points in the text, this does not necessarily mean that each reference refers to the same example or embodiment, or that a particular feature applies only to a single example or embodiment. Individual features of different examples and embodiments may also be combined to provide further embodiments.

[0125] A wireless communication system provides wireless communication to devices connected thereto. Typically, access points, such as base stations, are provided to facilitate communication. Below, different scenarios will be described using the 3GPP 5G access architecture with multi-beam capabilities as an example of an access architecture.

[0126] However, the examples are not necessarily limited to this architecture. Examples of other options for suitable systems are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE), LTE-A (LTE-Advanced), Wireless Local Area Networks (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth, Personal Communications Service (PCS), ZigBee, Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, Mobile Ad Hoc Networks (MANETs), Cellular Internet of Things (IoT) RAN and Internet Protocol Multimedia Subsystem (IMS) or any combination thereof and further developed systems.

[0127] Figure 1A wireless system 1 is shown that includes a radio access system 2. The radio access system may include one or more access points / nodes, or base stations 12. An access point may include any node capable of transmitting / receiving radio signals (e.g., one or more TRPs (Transmit Receive Points), such as 3GPP 5G base stations such as gNBs, eNBs, etc.).

[0128] The communication device 10 is located within the service area of ​​the radio access system and is therefore able to communicate with the access point 12. The communication 11 from the communication device 10 to the access point 12 is generally referred to as the uplink (UL). The communication 12 from the access point 12 to the device 10 is generally referred to as the downlink (DL).

[0129] Note that the wider communication system is shown only as Cloud 1 and may include multiple elements that are not shown for clarity. For example, a 5G-based system may consist of a terminal or user equipment (UE), a 5G radio access network (5GRAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), one or more application functions (AFs) and one or more data networks (DNs). The 5G-RAN may include one or more gNodeBs (GNBs) or one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) central unit functions. The 5GC may also include entities such as a network slice selection function (NSSF), a network open function, a network repository function (NRF), a policy control function (PCF), a unified data management (UDM), an application function (AF), an authentication server function (AUSF), an access and mobility management function (AMF) and a session management function (SMF).

[0130] The communication device 10 can be any suitable communication device adapted for wireless communication. The wireless communication device can be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) (for example, a mobile device such as a mobile phone or a so-called smart phone), a computer provided with a wireless interface card or other wireless interface facility (for example, a USB dog), a personal data assistant (PDA) or tablet computer provided with wireless communication capabilities, a machine type communication (MTC) device, an Internet of Things (IoT) type communication device or any combination of these, etc. The device can be provided as part of another device. The device can receive signals via an air or radio interface via a suitable device for receiving and can send signals via a suitable device for sending radio signals. Communication can occur via multiple paths. The term UE (user equipment) used in this document is intended to cover any communication device.

[0131] The access point 12 or the communication device 10 is provided with processing means comprising at least one processor and at least one memory. Figure 2 A data processing device 50 comprising processors 52 , 53 and a memory 51 is shown.

[0132] Figure 2 Further shown are connections between the components of the apparatus and interfaces for connecting the data processing apparatus to other components of the device. The at least one memory may include at least one ROM and / or at least one RAM. At least one processor may be coupled to the at least one memory. The at least one processor may be configured to execute appropriate software code to implement one or more of the following aspects. The software code may be stored in the at least one memory, such as in the at least one ROM.

[0133] The communication apparatus may include other possible components for use in software and hardware assisted execution of the tasks it is designed to perform, including control of access and communications to access systems and other communication devices.

[0134] consider Figure 3 The example shown. Access point 300 has 8 ports and communication device 302 has 4 antenna points. In the following example, all antenna ports of the UE are selected and four antenna ports of the access point are selected. This can achieve 4-layer DL MIMO (Multiple Input Multiple Output).

[0135] It should be noted that in some embodiments, more than four antenna ports may be selected to provide 4-layer DL MIMO.

[0136] For DL ​​MIMO, the antenna ports of the access point transmit signals that are received by the antenna ports of the communication device 302 .

[0137] It should be noted that in some embodiments, for 4-layer DL MIMO, the access point will have at least four antenna ports. Therefore, the access point can have more or fewer than eight antenna ports, and the required antenna ports are selected from these. Similarly, the UE will have at least four antenna ports. When the UE has more than four antenna ports, four ports are selected from those ports.

[0138] An access point can be designed with a fixed pair of ports (e.g., 1-2 and 3-4), each associated with an antenna array in the case of four antenna ports. That is, with two pairs of antenna ports, there will be two antenna arrays, each with X antennas (where X can be greater than 2). In FR2 scenarios, each array can generate different simulated beams in different directions. In FR2, the number of antenna ports and the number of antennas in the antenna array are unrelated. As an example, a gNB (or UE) may have one antenna port, but the antenna array may have, for example, 128 antennas. In this example, the signal from one antenna port is distributed across the 128 antennas of the antenna array and phase-shifted using beamforming weights to steer the signal (i.e., beam direction) in a specific direction. The beam is generated by the antenna array, but the signal arrives at the array from a single antenna port.

[0139] It should be noted that the example embodiments presently being described have the goal of implementing 4-layer DL MIMO (ie, rank 4). However, it should be understood that other embodiments may be used for n-layer MIMO, where n is two or more.

[0140] The TCI (Transmission Configuration Indicator) state defines the QCL (Quasi Co-location) source and QCL type for the target reference signal. This indicates the transmit configuration for the QCL relationship between the DL RSs (Downlink Reference Signals) included in an RS set. For example, if the DMRS of a PDSCH channel is characterized by a TCI state, for which the DMRS has a QCL type D relationship with a certain CSI-RS signal, this means that the DMRS of the PDSCH (and the PDSCH itself) can be considered to be transmitted from the same gNB as the one that transmitted the CSI-RS signal.

[0141] A pool of TCI states can be configured by RRC (Radio Resource Control). A subset of these configured states can be active at the same time. One TCI state in these active states can be indicated at a time.

[0142] TCI states can be combined (DL / UL) or separate (DL or UL). In the case of combined TCI states, the pool configured in RRC can be up to 128. In the case of separate TCI states, the DL pool can be up to 64 or 128, and the UL pool can be up to 32 or 64. In the RRC-configured TCI states, up to 8 TCI states can be active simultaneously.

[0143] Activation of the active TCI state is done via MAC-CE (Medium Access Control - Control Element).

[0144] When there is more than one active TCI state, the indication of the indicated TCI is done via DCI (Downlink Control Information), otherwise no DCI is required and the only active TCI state is also the indicated TCI state.

[0145] The DL signal characterized by the TCI state may be received by one or more or all panels used by the UE. The one or more panels receiving the RS characterized by the TCI state are the one or more active panels used in actual DL and UL transmissions.

[0146] In the RS grouping concept, DL RS signals received by a UE are considered to be part of the same group if they can be received simultaneously at the UE using the same UE Rx (receive) spatial filter or filter set (i.e., multiple spatial filters). For example, the spatial filter or filter set can be n receive beams (spatial filters). This can be signaled to the access point.

[0147] The UE may have one or more antenna panels. Each antenna panel may have one or more antenna ports. In this regard, reference is made to Figure 4a , the communication device 302 is shown having a first antenna panel 400 with first and second antenna ports 1 and 2. The communication device 302 has a second antenna panel 402 with third and fourth antenna ports 3 and 4. Antenna panels are provided at different locations on the communication device.

[0148] refer to Figure 4b , the communication device 302 is shown to have an antenna panel 404 having first to fourth antenna ports.

[0149] It should be noted that the number of antenna ports and / or the number of antenna panels may differ from the given Figure 4a and 4b In some embodiments, there may be more than two antenna panels. Different numbers of antenna ports may be provided on the antenna panels.

[0150] Some embodiments can be used with millimeter wave frequencies. For example, some embodiments can be used with the so-called FR2 (Frequency Range 2) of 5G. FR2 has operational frequencies in the millimeter wave region (above 24 GHz) that have been allocated to 5G.

[0151] In FR2, due to the analog front-end and beam steering implementation, each gNB beam (Tx spatial filter for DL) can only support 2 antenna ports. This means that two beams need to be configured simultaneously to transmit 4-layer DL MIMO. For those embodiments provided in this scenario, example methods can be provided to determine which two beams the gNB should configure for scheduled 4-layer DL MIMO to maximize the received throughput at the UE.

[0152] One method provided in Rel. 17 of the 5G standard for UEs to indicate potential TCI state pairs or simultaneous transmissions is a RAN1 (Radio Access Network) specified feature using packet-based beam reporting.

[0153] Using this packet-based beam reporting, the UE can indicate which DL beams can be received simultaneously by the UE. Using the RS information in the packet-based reporting, the gNB can activate and indicate the TCI state related to those packets for simultaneous reception by the UE. The UE reports L1-RSRP (reference signal received power) for the number of reported RSs. The report also includes a list of CSI-RS (channel state information reference signal) or SSB (synchronization signal block) resource pairs (i.e., in terms of CSI-RS or SSB index) that can be received simultaneously by the UE. The report also includes the differential RSRP value related to the RSRP of the first reported RS.

[0154] The UE reports some embodiments to react quickly to changing channel conditions, for example for beam management. These are called L1-RSRP and L1-SINR (Signal to Interference and Noise Ratio). These reports are sent as part of Channel State Information (CSI) via the PUCCH (Physical Uplink Control Channel).

[0155] However, for the gNB, this information is not sufficient to determine which are the sets of RSs, e.g., pairs, that will maximize rank and, therefore, throughput.

[0156] Some embodiments may provide methods and apparatus for providing rank-M beam discovery, meaning that M-layer communication is achieved by searching for beam pairs (or beam groups) that provide a rank equal to M. In the illustrated example, M is equal to 4, but in other examples, M may be any other suitable integer value of 2 or more.

[0157] Consider a scenario where M is 4, and each gNB beam can only support two antenna ports. In other words, in this scenario, at least two gNB beams are required to achieve 4-layer communication. However, the gNB can have up to 64 SSB indices, each of which can be associated with 4 CSI-RS indices. The UE has 2 panels. Each panel has 2 antenna ports. Therefore, there can be many combinations to explore. Currently, it is proposed that the gNB needs to try different candidate beam (i.e., reference signal index) combinations until a rank 4 is reported from the UE. For example, the gNB schedules a 2-port CSI-RS on the CSI-RS with index n and a 2-port CSI-RS on the CSI-RS with index m. For example, if the UE only sees rank 2, this is reported to the gNB and the gNB again tries to schedule a 2-port CSI-RS on the CSI-RS with index n+1 and a 2-port CSI-RS on the CSI-RS with index m+1 until the UE reports rank 4.

[0158] In another approach, where the DL RSs are not transmitted simultaneously but continuously, the network may first configure the UE to report L1-RSRP+RI on four beams (these beams may be, for example, SSB#1, CSI#1, CSI#2, and CSI#3). The UE may then receive the 2-port CSI-RS on beam CSI#1, followed by the 2-port CSI-RS on beam CSI#2, and so on. The UE measures L1-RSRP and RI independently on each beam, one at a time. The UE then reports the values ​​for each beam, for example, CSI#1: L1-RSRP = -80dBm RI = 2, CSI#2: L1-RSRP = -82dBm RI = 2, CSI#3: L1-RSRP = -90dBm RI = 1. The network may therefore decide that the 4-port CSI-RS should be scheduled on CSI#1, since this CSI#1 provides the best RSRP and has the opportunity to provide rank 4. Thereafter, the network updates the CSI reporting configuration accordingly and sends a 4-port CSI-RS on CSI#1 (in FR2, this can be done with two beams, each with the same Tx spatial filter and 2 ports). The UE then measures the rank but determines that the rank is still only rank 2. Therefore, the UE reports RI=2 on CSI#1. The network must then try again to get rank 4, for example, on CSI#2, then on CSI#3, then on the combination of CSI#1 and CSI#2, then on the combination of CSI#2 and CSI#3, and so on, until the UE reports rank 4 (if any).

[0159] As mentioned, FR2 gNB implementations may only support two antenna ports per gNB beam, and therefore per CSI-RS index. In this case, different beam pairs need to be tried by the gNB to achieve rank-4 transmission to a particular UE. This may increase the complexity and / or time of searching for a beam pair for rank-4 transmission, resulting in resource consumption and / or a lengthy process.

[0160] As an example, if the gNB has 4 CSI-RS beams and the UE has only 1 beam, the gNB will need to try up to 16 (4*4) CSI-RS beam combinations, where each beam is associated with a fixed pair of antenna ports (out of 4 in total), to search for a combination that provides a channel of rank 4. Considering the scenario with more than one UE beam and a large number of CSI-RS beams, the current approach becomes more complicated.

[0161] In a TRP scenario with two or more TRPs, this search can be laborious, and can be exacerbated if the TRPs are not collocated.

[0162] In some embodiments, a method is provided for a UE to estimate an M×M channel matrix for transmissions through an access point's M antenna ports. The UE can reconstruct the M×M channel matrix. When the access point transmits using only a subset of the M antenna ports, some embodiments use observations of each subset of the M×M channel matrix. In some embodiments, the UE receives transmissions from all M antenna ports of a subset of the access point's antenna ports. The UE can receive transmissions from different subsets of the access point's M antenna ports. In this example, the UE has M antenna ports.

[0163] Some embodiments may result in a smaller number of measurements being performed on the UE side to find and thus index a CSI-RS beam (beam pair or beam group), enabling rank M communication.

[0164] As an example, M can be 4. When the access point transmits using only a subset of the 4 antenna ports (e.g., a pair of 2 antenna ports) but the UE receives using all 4 of its antenna ports, the UE can reconstruct the 4×4 channel matrix transmitted by the 4 ports of the access point from its respective observations of the subset of the 4×4 channel matrix over time. When the access point transmits using only 2 antenna ports (as a subset of the 4 antenna ports), the subset of the 4×4 channel matrix can have a size of 4×2.

[0165] This approach may result in a smaller number of measurements being performed on the UE side to find the CSI-RS beam pairs enabling rank 4 communication.

[0166] Hereinafter, a gNB or access point beam may be referred to as a CSI-RS beam. However, it should be understood that in other embodiments, the beam may be any other suitable reference signal beam, such as an SSB beam.

[0167] refer to Figure 5 , which illustrates the signal flow of some embodiments.

[0168] As shown in reference S1, the UE provides capability information to the access point. The capability information may include a capability indication. The capability information may indicate to the access point that the UE is capable of reconstructing a 4×4 channel matrix from respective measurements of reference signals transmitted using different subsets of antenna ports (e.g., 2 out of 4 antenna ports). The reference signal resources may be CSI-RI resources. Different reference signal resources may be associated with different pairs of antenna ports of the access point. A pair is an example of a subset of antenna ports of the access point. A subset means two or more antenna ports of the access point, but fewer than all antenna ports of the access point.

[0169] The UE may report the ability to reconstruct a 4×4 channel matrix from respective measurements of two or more CSI-RS resources associated with different pairs of gNB antenna ports.

[0170] The capability may be reported to the access point using any suitable information. The capability may be reported via UL RRC information. This may be provided in the UL RRC information field.

[0171] This capability may be provided by the UE in response to a request from the gNB.

[0172] In some embodiments, capability indication reporting may not be required. The gNB may assume that the UE is capable of reconstructing the channel matrix.

[0173] The UE may report whether the channel it is currently experiencing is stable over time. This may be reported together with the capability indication, or separately. Figure 5 It is represented by S2 in the example, but can be combined with S1.

[0174] The channel stability report may occur later than S1, for example after any of S3 to S11. The channel stability report may be made at fixed intervals. The channel stability report may be made only in response to a change in channel conditions exceeding a threshold.

[0175] This reporting can be done dynamically or semi-statically.

[0176] In case of semi-static signaling, reporting is indicated to the gNB via RRC information.

[0177] In the case of dynamic signaling, the reporting is indicated to the gNB via physical layer signaling. For example, this can be indicated in a field in the MAC-CE or PUCCH (Physical Uplink Control Channel).

[0178] In one example implementation, the UE may measure relatively small-scale and / or relatively large-scale parameters of a channel over a period of time. The UE may indicate to the gNB an amount of time (e.g., in symbols, slots, ms) that one or more of these parameters have not changed by more than a threshold.

[0179] The threshold may be internal to the UE and / or indicated by the gNB.

[0180] The gNB configures CSI-RS resources associated with different pairs of gNB antenna ports. This may be configured in response to the gNB receiving a capability indication and / or a channel stability report from the UE.

[0181] In one embodiment, the CSI-RS resources are configured in the time domain such that the second pair of antenna ports are transmitted on all CSI-RS beams and measured by a set of antenna ports (all or a common set) of the UE only after the first pair of antenna ports have been transmitted on all CSI-RS beams and measured by a set of antenna ports (all or a common set) of the UE.

[0182] This embodiment can be applicable to the case where the gNB requires a lot of time to switch antenna ports due to RF reconfiguration and the channel is stable over time.

[0183] In another embodiment, the CSI-RS resources are configured in the time domain such that after a first pair of antenna ports have been transmitted on the same CSI-RS and measured by a set of antenna ports (the full set or a common set) of the UE, a second pair of antenna ports is transmitted on one CSI-RS beam and measured by a set of antenna ports (the full set or a common set) of the UE.

[0184] This embodiment can be applicable to situations where the gNB does not need a lot of time to switch antenna ports due to RF reconfiguration and the channel is unstable over time.

[0185] Thus, in some embodiments, a given CSI-RS index may be associated with one or more beams from two, more, or all of the different antenna subsets. In other embodiments, a given CSI-RS index may be associated with only one of the different antenna subsets.

[0186] exist Figure 5 In the example shown, four CSI-RS resources are configured in one slot associated with the first pair of antenna ports, and another four CSI-RS resources are configured in the subsequent slot n+1 associated with the second pair of antenna ports. A CSI resource is a CSI-RS resource in the time-frequency grid. A CSI-RS beam is a gNB beam associated with a specific CSI-RS resource, e.g., a gNB beam used to transmit a CSI-RS resource.

[0187] In this example, the gNB will first detect the first pair of antenna ports on all CSI-RS beams in slot n and the second pair of antenna ports on all CSI-RS beams in slot n + 1. The assumption in this example is that the gNB has 4 CSI-RS beams.

[0188] In some embodiments, one or more CSI-RS beams transmitted by one antenna port in an antenna port pair may have the same CSI-RS / SSB index as one or more CSI-RS beams transmitted by the other pair. Because beams with the same CSI-RS / SSB index come from different subsets of antenna ports and are transmitted using different resources, different beams transmitted by different subsets of antenna ports are distinguished. The report provided by the UE to the gNB (discussed later) may have the structure [ab], where a is the first CSI-RS / SSB index and refers to the first subset of antenna ports, and b is the second CSI-RS / SSB index and refers to the second subset of antenna ports.

[0189] In some embodiments, any one of the CSI-RS beams transmitted by one antenna port in an antenna port pair does not have the same CSI-RS / SSB index as any CSI-RS beam transmitted by the other pair in the pair.

[0190] In S4, the access point transmits four 2-port CSI-RSs (ie, with corresponding CSI-RS beams) in time slot n.

[0191] In S5 , the UE measures the four 2-port CSI-RSs (ie, from the corresponding CSI-RS beams) transmitted at time slot n and received using its four antenna ports.

[0192] In S6, the UE estimates a first channel matrix H1 from the access point to the UE for a first pair of antenna ports of the access point. This will be discussed in more detail below.

[0193] In S7, the access point transmits four 2-port CSI-RSs (ie, with corresponding CSI-RS beams) in time slot n+1.

[0194] In S8 , the UE measures the four 2-port CSI-RS (ie, from the corresponding CSI-RS beams) transmitted in time slot n+1 and received using its four antenna ports.

[0195] In S6 , the UE estimates a second channel matrix H2 from the access point to the UE for a second pair of antenna ports of the access point.

[0196] As an example, let us consider a first CSI-RS beam associated with a first pair of gNB antenna ports and a second CSI-RS beam associated with a second pair of gNB antenna ports, where the first and second CSI-RS beams are not necessarily different.

[0197] The first pair of antenna ports at the gNB is represented by antenna ports numbered 1 and 2, while the second pair is represented by antenna ports numbered 3 and 4. For example, h 23 Denotes the channel coefficient between the third antenna port (belonging to the second pair) at the gNB and the second antenna port (of the 4 UE antenna ports, represented in the row of the matrix) at the UE.

[0198] The UE estimates H1 and H2 from 8 CSI-RS resources (once per CSI-RS beam).

[0199] In S10, the UE combines H1 and H2 to form a 4×4 channel matrix H = [H1, H2]. This matrix can be regarded as a reconstructed channel matrix. This is a combined channel obtained by combining the channels between the first pair of antenna ports and the UE and between the second pair of antenna ports and the UE.

[0200] By combining the measurements associated with the first pair of gNB antenna ports with the measurements associated with the second pair of gNB antenna ports, the UE estimates the rank of the channel matrix H for each of the 16 combinations it constructs. This rank can be considered the joint rank of the combined channel. With this joint reporting method, the UE does not need to report the rank until it has received and measured CSI-RS from each of the at least two subsets of the access point's antenna ports. Therefore, signaling can be reduced compared to the prior art method in which the UE reports the rank sequentially for each CSI-RS.

[0201] If at least one beam pair is capable of supporting rank 4, the UE reports the beam pairs capable of rank 4 transmission to the gNB.

[0202] In some embodiments, where multiple beam pairs are capable of supporting rank 4, the UE may report all of these beam pairs or only a subset of these beam pairs.

[0203] If the maximum supported rank is 3, the UE reports to the gNB the beam pairs (or subset of beam pairs) that can transmit with rank 3.

[0204] If the maximum supported rank is 2, the UE reports to the gNB the beam pairs (or subset of beam pairs) that can transmit with rank 2.

[0205] If there is no beam pair capable of supporting rank greater than 1, the UE may continue to operate with maximum rank 1 transmission on a single gNB CSI-RS beam.

[0206] In some embodiments, the reconstructed channel matrix may be sent by the UE to the access node.

[0207] Some embodiments include a UE that has the capability to measure two or more CSI-RS resources associated with different subsets of gNB antenna ports at different times. For example, at the UE, each pair is measured using four antenna ports. The UE can reconstruct a 4×4 channel matrix from these measurements.

[0208] Depending on the configuration, the measurements of different pairs of gNB antenna ports may be continuous or discontinuous.

[0209] Signal measurements are performed at the UE using a different number of RX antenna ports (eg, 4) than the number of TX antenna ports (2), and stored at the UE until measurements on both pairs of TX antenna ports have been performed.

[0210] The UE reports channel stability over time to help the gNB make scheduling decisions when triggering measurements.

[0211] This can be useful, for example, in cases where a large number of CSI-RS beams need to be measured and the second pair of gNB antenna ports is transmitted by the gNB only after the first pair of antenna ports has been sounded on all CSI-RS beams.

[0212] The channel stability over time can be measured at the UE, for example by observing the evolution of the channel when measuring the SSB signal.

[0213] The channel stability experienced by the UE may be reported in symbols, slots or seconds (e.g. milliseconds) or more simply as ACK (acknowledgement) or NACK (negative acknowledgement) if the phase and / or amplitude of the channel frequency response does not vary by more than a threshold within a time interval.

[0214] Some embodiments may reduce the overhead required to determine whether a beam pair supports rank-4 (or other rank) DL transmission.

[0215] For example, in some embodiments, if the gNB has four CSI-RS beams, the gNB transmits the four CSI-RS beams twice. Each time, the four beams are associated with a different subset of the gNB's two antenna ports. This requires only eight CSI-RS transmissions. This can be only 50% of the resources used in existing methods when beam pairs are directly tested (in which case 16 CSI-RS transmissions are required).

[0216] The greater the number of beams to be tested, the greater the gain achieved by the embodiments. If the gNB has 10 CSI-RS beams, then the existing method would need to probe 100 (i.e., 10×10) combinations. In some embodiments, only 20 (i.e., 2×10) CSI-RS transmissions would be required. This may be only 20% of the resources used in the existing method when beam pairs are directly tested.

[0217] For example, in the prior art method, the UE reports the rank (1 or 2) to the network separately for M-DCI, while the embodiments given herein enable the UE to report a joint rank (1, 2, 3 or 4).

[0218] In the embodiment, the reference signals transmitted by different subsets of antennas may be transmitted on different resources. In the described example, the different resources may be different time resources. In other embodiments, the different resources may be frequency resources or any other suitable resources.

[0219] Some embodiments can be used with multiple TRPs. For example, one TRP can provide one subset of antenna ports and another TRP can provide another subset of antenna ports. The first and second TRPs can be part of the same gNB but can be physically separated from each other.

[0220] In this regard, reference Figure 6 Example shown. Figure 6 A gNB 600 is shown with a first TRP 604a and a second TRP 604b. Each TRP in this example has two antenna ports. Each TRP transmits a CSI-RS beam to a UE 602. UE 602 uses the CSI-RS beams received from both TRPs to generate a 4×4 channel matrix, where channels are provided between the TRPs and the UE. In this example, there are two TRPs. In other embodiments, more than two TRPs may be associated with the gNB.

[0221] A TRP can support sDCI (single downlink control information) or mDCI (multiple downlink control information). In sDCI, there will be only one DCI message sent to the UE from one of the TRPs (the anchor TRP). On the other hand, mDCI will have two DCI messages sent from two TRPs, one DCI for each TRP. Having two DCI messages makes it possible for the two TRPs to send with two different MCSs (modulation and coding schemes), thus sending two transport blocks. Embodiments can ensure that the selected beam maximizes the rank of the channel between the TRP and the UE regardless of the operating mode of the TRP.

[0222] refer to Figure 7 , which illustrates the methods of some embodiments.

[0223] The method may be performed by an apparatus, which may be in or be a communication device.

[0224] The apparatus may comprise suitable circuitry for providing the method.

[0225] Alternatively or additionally, the apparatus may include at least one processor and at least one memory storing instructions, the instructions being, when executed by the at least one processor, to cause the apparatus to at least provide the following method.

[0226] Alternatively or additionally, the device may be, for example, Figure 2 discussed.

[0227] The methods may be provided by computer program code or computer executable instructions.

[0228] Referring to S1, the method may include determining joint rank information associated with a combined channel using multiple received reference signals. The multiple received reference signals are received from an access point. The multiple reference signals are transmitted via different subsets of antenna ports of the access point. The different subsets of antenna ports use different resources for transmitting the reference signals. The combined channel is between antenna ports of different subsets of antenna ports of the access point and the antenna port that receives the multiple reference signals.

[0229] Referring to S2, the method may include causing information to be sent to the access point regarding determination of joint rank information associated with the combined channel.

[0230] It should be understood that Figure 7 The method outlined in can be modified to include any of the features previously described.

[0231] The method of some embodiments is illustrated with reference to FIG8 .

[0232] The method may be performed by an apparatus. The apparatus may be in an access node or be an access node.

[0233] The apparatus may comprise suitable circuitry for providing the method.

[0234] Alternatively or additionally, the apparatus may include at least one processor and at least one memory storing instructions, the instructions being, when executed by the at least one processor, to cause the apparatus to at least provide the following method.

[0235] Alternatively or additionally, the device may be, for example, Figure 2 discussed.

[0236] The methods may be provided by computer program code or computer executable instructions.

[0237] With reference to T1, the method may include causing a plurality of reference signals to be transmitted to a communication device. The plurality of reference signals are transmitted via different subsets of antenna ports of an access point. The different subsets of antenna ports use different resources for transmitting the reference signals.

[0238] Referring to T2, the method may include receiving joint rank information from the communication device, the joint rank information relating to a combined channel between antenna ports of different subsets of antenna ports of the access point and antenna ports of the communication device receiving the plurality of reference signals.

[0239] It will be appreciated that the method outlined in FIG. 8 may be modified to include any of the features previously described.

[0240] The computer program code may be downloaded and stored in one or more memories of the relevant apparatus or device.

[0241] Thus, although certain embodiments described above are described by way of example with reference to certain example architectures for wireless networks, technologies, and standards, the embodiments may be applied to any other suitable forms of communication systems besides those illustrated and described herein.

[0242] It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0243] As used herein, “at least one of: ” and “at least one of ” and similar terms mean at least any one of the elements or two or more of the elements, or at least all of the elements, where the list of two or more elements is joined by “and” or “or”.

[0244] In general, various embodiments may be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects of the present disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device, although the present disclosure is not limited thereto. Although various aspects of the present disclosure may be illustrated or described as block diagrams, flow charts, or using some other graphical representation, it should be understood that these block diagrams, devices, systems, techniques, or methods described herein may be implemented as non-limiting examples in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0245] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) implemented only in hardware circuits (e.g., implemented only in analog and / or digital circuits) and (b) a combination of hardware circuitry and software, such as (if applicable): (i) a combination of analog and / or digital hardware circuits with software and / or firmware and (ii) any portion of a hardware processor (including a digital signal processor) with software that works in conjunction with the software and memory to cause a device such as a mobile phone or server to perform various functions, and (c) Hardware circuits and / or processors, such as microprocessors or portions of microprocessors, that require software (e.g., firmware) for operation, but where software is not required for operation, the software may not be present.

[0246] The definition of "circuitry" in this application applies to all uses of this term, including in any claims. As a further example, as used in this application, the term "circuitry" also covers merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor, and its accompanying software and / or firmware implementation. For example, and if appropriate to the particular claim element, the term "circuitry" also covers an integrated circuit, such as a baseband integrated circuit or processor integrated circuit used in a mobile device or server, a cellular network device, or other computing or networking device.

[0247] The embodiments of the present disclosure may be implemented by computer software executed by a data processor of a mobile device, for example in a processor entity, or by hardware, or by a combination of software and hardware. Computer software or programs, also referred to as program products, including software routines, applets and / or macros, may be stored on any readable device data storage medium and include program instructions to perform specific tasks. A computer program product may include one or more executable computer components that, when the program is run, may be configured to implement an embodiment. The one or more executable computer components may be at least one software code or a portion thereof.

[0248] In this regard, it should be noted that any block of the logic flow as shown in the figure may represent program steps, or connected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on physical media such as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disks or floppy disks, and optical media such as DVDs and their data variants, CDs. Physical media is non-transitory media.

[0249] The term "non-transitory" as used herein refers to the limitations of the medium itself (ie, tangible rather than signaling) rather than limitations on data storage persistence (eg, RAM versus ROM).

[0250] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory. As non-limiting examples, the data processor may be of any type suitable for the local technical environment and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an FPGA, gate-level circuits, and processors based on multi-core processor architectures.

[0251] Embodiments of the present disclosure can be practiced in various components, such as integrated circuit modules. The design of integrated circuits is a highly automated process. Complex and powerful software tools are available to convert logic-level designs into semiconductor circuit designs ready to be etched and formed on semiconductor substrates.

[0252] The foregoing description has provided, by way of non-limiting examples, a complete and informative description of exemplary embodiments of the present disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant art in view of the foregoing description when read in conjunction with the accompanying drawings and the appended claims. Indeed, there are further embodiments including combinations of one or more embodiments with any of the other embodiments described hereinabove. The scope of protection of some embodiments of the present disclosure is set forth in the claims. The embodiments and features (if any) described in this specification that do not fall within the scope of the claims should be interpreted as examples to aid in understanding the various embodiments of the present disclosure. It should be noted that different claims with different claim scopes may be applied in related applications, such as divisional or continuation applications.

Claims

1. A device comprising: means for determining joint rank information associated with a combined channel using a plurality of received reference signals received from an access point, the plurality of reference signals being transmitted via different subsets of antenna ports of the access point, the different subsets of antenna ports using different resources for transmitting reference signals, the combined channel being a result of a union of respective channels between the antenna port of each of the different subsets of antenna ports of the access point and the antenna port receiving the plurality of reference signals; as well as means for causing information to be sent to said access point relating to said determination of said joint rank information, said joint rank information being associated with said combined channel.

2. The apparatus according to claim 1, comprising: means for receiving the plurality of reference signals from the access point, the plurality of reference signals being transmitted over the different subsets of antenna ports of the access point.

3. The apparatus of claim 1 or 2, wherein a first subset of the plurality of reference signals is transmitted through a first subset of the antenna ports, and a second subset of the plurality of reference signals is transmitted through a second subset of the antenna ports.

4. The apparatus of claim 3 , wherein the first subset of the plurality of reference signals is sent via the first subset of the antenna ports using one or more time resources that are different from time resources used to send the second subset of the plurality of reference signals via the second subset of the antenna ports.

5. The apparatus according to any one of claims 1 to 4, wherein the access point comprises a plurality of transmit-receive points, one subset of the different subsets of antenna ports is associated with one of the plurality of transmit-receive points, and another subset of the different subsets of antenna ports is associated with another transmit-receive point of the plurality of transmit-receive points.

6. The device according to any one of the preceding claims, comprising: means for causing information to be sent to the access point, the information indicating to the access point that the apparatus is capable of supporting use of reference signals sent by different subsets of the antenna ports of the access point using different resources to determine joint rank information between the antenna ports of the access point and the apparatus associated with a combined channel.

7. The apparatus of any preceding claim, wherein the apparatus comprises antenna ports, the common set of antenna ports being configured to receive the plurality of reference signals. The apparatus of claim 7 , wherein the common set of antenna ports comprises all of the ports of the apparatus.

9. The apparatus according to any of the preceding claims, wherein the means for using the received plurality of reference signals is configured for reconstructing a combined channel matrix from the individual channel matrices, the combined channel matrix comprising channel coefficients representing the combined channel.

10. The apparatus of any preceding claim, wherein the information sent to the access node comprises information regarding one or more reference signal indices associated with transmitting one or more of the plurality of reference signals via a corresponding subset of the antenna ports of the access point.

11. The apparatus according to any one of the preceding claims, wherein the means for determining joint rank information using the received multiple reference signals is used to determine whether the combined channel can achieve a target rank.

12. The apparatus according to any of the preceding claims, wherein the reference signal comprises a channel state information reference signal and / or a synchronization signal block.

13. An apparatus comprising: means for causing a plurality of reference signals to be transmitted to a communications device, the plurality of reference signals being transmitted via different subsets of antenna ports of an access point, the different subsets of antenna ports utilizing different resources for transmitting reference signals; as well as means for receiving joint rank information from the communication device, the joint rank information relating to a combined channel between the antenna ports of the different subsets of the antenna ports of the access point and an antenna port of the communication device receiving the plurality of reference signals.

14. The apparatus of claim 13 , wherein the means for causing causes a first subset of the plurality of reference signals to be transmitted via a first subset of the antenna ports using one or more time resources that are different from time resources used to transmit a second subset of the plurality of reference signals via a second subset of the antenna ports.

15. An apparatus according to claim 13 or 14, wherein the access point includes multiple transmission-reception points, one subset of the different subsets of antenna ports is associated with one of the multiple transmission-reception points, and another subset of the different subsets of antenna ports is associated with another transmission-reception point of the multiple transmission-reception points.

16. The device according to any one of claims 13 to 15, comprising: means for receiving information from the communications device, the information indicating that the communications device is capable of supporting use of reference signals transmitted by different subsets of the antenna ports of the access point using different resources to determine joint rank information between the antenna ports of the access point and the communications device associated with a combined channel.

17. The apparatus according to any one of claims 13 to 16, wherein the received joint rank information comprises information about one or more reference signal indices associated with one or more reference signals of the plurality of reference signals transmitted through a corresponding subset of the antenna ports of the access point.

18. A method comprising: determining joint rank information associated with a combined channel using a plurality of received reference signals received from an access point, the plurality of reference signals being transmitted via different subsets of antenna ports of the access point, the different subsets of antenna ports using different resources for transmitting reference signals, the combined channel being between the antenna ports of the different subsets of antenna ports of the access point and an antenna port on which the plurality of reference signals are received; as well as Information is caused to be sent to the access point regarding the determination of the joint rank information associated with the combined channel.

19. A method comprising: causing a plurality of reference signals to be transmitted to a communications device, the plurality of reference signals being transmitted via different subsets of antenna ports of an access point, the different subsets of antenna ports using different resources for transmitting reference signals; as well as Joint rank information is received from the communications device, the joint rank information relating to a combined channel between the antenna ports of the different subsets of the antenna ports of the access point and an antenna port of the communications device receiving the plurality of reference signals.

20. A computer program comprising: Computer executable code which, when run on at least one processor, causes the method of claim 18 or claim 19 to be performed.

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