WO2021194926A1

WO2021194926A1 - Ue split architecture with distributed tx/rx chains

Info

Publication number: WO2021194926A1
Application number: PCT/US2021/023404
Authority: WO
Inventors: Dawid Koziol; Ling Yu; Daniela Laselva
Original assignee: Nokia Technologies Oy; Nokia Of America Corporation
Priority date: 2020-03-23
Filing date: 2021-03-22
Publication date: 2021-09-30

Abstract

An apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: provide a central unit associated with a medium access control layer and at least one other protocol layer; provide one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and provide an internal interface for each of the one or more distributed units for connection to the central unit.

Description

UE SPLIT ARCHITECTURE WITH DISTRIBUTED TX/RX CHAINS

TECHNICAL FIELD

[0001] The examples and non-limiting embodiments relate generally to communications and, more particularly, to a UE split architecture with distributed Tx/Rx chains.

BACKGROUND

[0002] It is known to implement redundancy in a wireless communication network.

SUMMARY

[0003] In accordance with an aspect, an apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: provide a central unit associated with a medium access control layer and at least one other protocol layer; provide one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and provide an internal interface for each of the one or more distributed units for connection to the central unit.

[0004] In accordance with an aspect, an apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: receive an indication of independent transceiver chains implemented as independent one or more distributed units; provide a separate physical layer and measurement configuration for each of the independent transceiver chains; provide a single configuration of higher layer protocols; and provide at least one control message for application to the one or more distributed units.

[0005] In accordance with an aspect, a method includes providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

[0006] In accordance with an aspect, a method includes receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

[0007] In accordance with an aspect, a non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations is provided, the operations comprising: providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

[0008] In accordance with an aspect, a non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations is provided, the operations comprising: receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

[0009] In accordance with an aspect, an apparatus includes means for providing a central unit associated with a medium access control layer and at least one other protocol layer; means for providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and means for providing an internal interface for each of the one or more distributed units for connection to the central unit.

[0010] In accordance with an aspect, an apparatus includes means for receiving an indication of independent transceiver chains implemented as independent one or more distributed units; means for providing a separate physical layer and measurement configuration for each of the independent transceiver chains; means for providing a single configuration of higher layer protocols; and means for providing at least one control message for application to the one or more distributed units.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein: [0012] FIG. 1 is a block diagram of one possible and non-limiting system in which the example embodiments may be practiced.

[0013] FIG. 2 is a diagram depicting redundant user plane paths with multi-UE devices (solution 2 in TR 23.725).

[0014] FIG. 3 is a diagram depicting utilization of redundant user plane paths with the IEEE TSN FRER mechanism (from 3 GPP TS 23.725).

[0015] FIG. 4 is an illustration of two network architectures, wherein the left side depicts a 5G-RAN distributed and split CU-DU architecture for both user plane (UP) and control plane (CP), and wherein the right side depicts a multi-TRP transmission architecture.

[0016] FIG. 5 is a block diagram illustrating the difference between a multi-UE device (top) and a device with a UE split architecture (bottom).

[0017] FIG. 6 shows a block diagram illustrating an example UE split architecture as described herein, annotated by a summary of example UE configuration rule modifications to account for the UE split architecture.

[0018] FIG. 7 is a block diagram depicting an example split UE architecture used in user plane redundancy solutions, based on the examples described herein.

[0019] FIG. 8 is another example apparatus, which may be implemented in hardware, configured to implement a UE split architecture with distributed Tx/Rx chains, based on the examples described herein.

[0020] FIG. 9 is an example method to implement a UE split architecture with distributed Tx/Rx chains.

[0021] FIG. 10 is an example method to implement a UE split architecture with distributed Tx/Rx chains.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0022] Turning to FIG. 1, this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of FIG. 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0023] The RAN node 170 in this example is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node hosting radio resource control (RRC), SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the FI interface connected with the gNB-DU. The FI interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the FI interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

[0024] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memoiy/memories and processor(s), and/or other hardware, but these are not shown.

[0025] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 150 may be implemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0026] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0027] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH/DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node 170 to the RRH/DU 195. Reference 198 also indicates those suitable network link(s).

[0028] It is noted that description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0029] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(S)) and/or user plane functions (UPF(s)) and/or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality. These are merely example functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to the network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N W I/F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations.

[0030] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0031] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, network element(s) 190, and other functions as described herein.

[0032] In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0033] The examples described herein are related to 5G New Radio URLLC and, in particular, to the RAN protocol architecture targeted for 3 GPP Rel-17 and beyond where the Tx/Rx architecture in the UE is split into one or more distributed units and one central unit.

[0034] The methods to further enhance performance of URLLC services were studied as part of the SA2-led 3 GPP Rel-16 Study Item on IIoT/URLLC and the results were captured in 3 GPP TR 23.725. One of the studied issues was how to improve the end-to-end (E2E) reliability achievable over 5G systems, which is especially important for new services such as those related to Industrial Internet of Things (IIoT) such as factory automation, smart grid operations, etc. Since any service down-times are unacceptable for such applications, not only the full redundancy of data paths in the network is required, but also hardware redundancy of the network nodes along these paths might be needed to avoid unavailability due to hardware failure. One of the solutions considered by 3GPP SA2 WG was then to achieve complete E2E user plane redundancy, provided by having multi-UE devices as depicted in FIG. 2.

[0035] Thus FIG. 2 is a diagram 200 depicting redundant user plane paths with multi-UE devices (solution 2 in TR 23.725 version 16.2.0). As can be seen in FIG. 2, there is no single point of failure in the 5G system as the redundant paths are using two different User Plane Functions (UPFs) (UPF1 and UPF2) in the 5G Core Network, two different gNBs (gNBl and gNB2) in the RAN network while the end device (e.g. the “Multi-UE Device” or industrial controller) is equipped with two UEs (UE1 and UE2), each of them terminating one of the paths. Such an architecture can be, for example, leveraged by the IEEE Time Sensitive Networking (TSN) Frame Replication and Elimination for Reliability (FRER) mechanism, which can duplicate the data packets to be exchanged between the two hosts in the TSN network where each of them would be delivered to the same device by using different paths in the network. This is presented on FIG. 3. Accordingly, FIG. 3 is a diagram 300 depicting utilization of redundant user plane paths with the IEEE TSN FRER mechanism (from 3GPP TS 23.725).

[0036] Each of the UEs belonging to the same device, has its own radio connection with the RAN network and its own PDU session established with the 5G Core Network (5GC). To achieve full path redundancy, as mentioned above, two different gNBs and UPFs are used. However, if the most probable point of failure is assumed to be the UE, then also architectures with a multi-UE device where each of the UEs is connected to a single gNB/UPF could also be considered since it would be more cost-effective.

[0037] Even though placing two UEs inside a single device improves the reliability of the overall end to end connection, it has two main disadvantages. First, to fully take advantage of two UEs used for redundancy in a single device either standardization of inter-UE coordination, an inter- UE interface, or some tweaks on the network side are required. The latter may comprise, for example, the separation of data paths terminated at a single device for increasing diversity or the use of soft combining of the data duplicates received via the two UEs in the device. Second, using two UEs increases the cost of the device as hardware and software components of the UE may need to be duplicated and integrated in the device.

[0038] Especially the first point was raised during the discussions in 3GPP in Rel-16 as a problem from UE vendors’ point of view. Eventually, it was decided that in Rel-16, no standardized solution for support of multi-UE devices will be specified because of that. The examples described herein address it: how to exploit the presence of two UEs in a device in an efficient manner, avoiding inter-UE coordination. [0039] Utilizing two UEs in a single device with completely disjoint data paths was considered by SA2 (Solution #2 in TR 23.725). However, it was not brought into the normative phase, mainly due to concerns from UE vendors on having to standardize inter-UE coordination/interface as mentioned above.

[0040] FIG. 4 is an illustration 400 of two network architectures, wherein the left side (402) depicts a 5G-RAN distributed and split CU-DU architecture for both user plane (UP) and control plane (CP), and wherein the right side (404) depicts a multi-TRP transmission architecture. A RAN split architecture with a higher layer separation into a Central Unit (CU) controlling one or more of Distributed Units (DU) on the network side is supported in Rel-15 of the 5G-RAN system (3GPP TS 38.401). Various split options were additionally considered during the Rel-14 NR Study Item phase including a lower layer split as illustrated in the left side (402) of FIG. 4. Also, in multi-TRP cell deployments, separation is done in the lower layers, i.e., the PHY layer is separated as shown in the right side (404) of FIG. 4. In addition, distributed antenna systems (DAS) are also a common technique used at the network side, having the antennas distributed in space, for increasing coverage and capacity. The above architectures, where a function split is applied at one or more protocol layers at the network side has potential because of reduced cost, improved scalability, and more efficient scheduling coordination. However, none of these splitting architectures have been applied nor considered on the UE side currently since they are not straightforward to apply at the UE. The related challenges are addressed and resolved by the examples described herein.

[0041] The examples described herein provide a RAN protocol split architecture in the UE, where the UE is split into a central and one or more distributed units (similarly to the case of CU- DU split architecture on the network side). There may be some differences, however, both with the main assumptions, with the implementation, and its usage as explained herein.

[0042] The main design principles of the provided UE split protocol stack architecture are described next. FIG. 5 is a block diagram 500 illustrating the difference between a multi-UE device (top 502) and a device with a UE split architecture (bottom 504).

[0043] There is a single logical UE-CU entity 506 and one or more UE-DU entities (such as UE-DUl 507 and UE-DU2 508) connected with an internal interface. Even though a UE-CU 506 is presented as a single logical entity, it may also have redundant hardware to provide full redundancy of the UE hardware (that is similar or equivalent to that of multi-UE device 502).

[0044] UE-DUs (such as UE-DUl 507 and UE-DU2 508) are separate physical entities (e.g. they are physically distributed), but any UE-DU is associated with a single user device, such as user equipment 505. Due to the fact that the UE-DUs are separated in space, they may experience different radio conditions and can take advantage of spatial diversity even when they are connected to the same gNB. The minimum distance between any two UE-DUs, which should ensure adequate diversity, may be indicated by means of UE capability. As a non-limiting example, this may be realized for a robot where two or more UE-DUs are deployed at different arms of the robot.

[0045] The split may be introduced between the PHY and MAC layers (refer to MAC 510, PHY 512, and PHY 513) as it brings the most benefits, e.g. in terms of: the cost efficiency of the UE hardware, the enabling of soft-combining of the data received by each of the UE-DUs etc. For instance, two UE-DUs could operate at very different frequency bands, e.g. sub-6GHz and mmW, respectively. As opposed to a CU-DU split at the network side, the interface between CU 506 and each DU (such as UE-DU1 507 and UE-DU2 508) does not have to be standardized as there is no need for (multi-vendor) inter-operability between UE CU 506 and UE DUs (e.g., UE-DU1 507 and UE-DU2 508). This way, the main reproach towards the multi-UE device-based solutions (i.e. the concern about having to standardize coordination between the UEs in the same device 502) can be addressed. In the downlink, the DU (e.g., UE-DU1 507 or UE-DU2 508) receiving a DCI with a DL scheduling grant, may decode the associated transport block and provide the MAC PDU(s) to the MAC layer 510. In the uplink, a DU (e.g., UE-DU1 507 or UE-DU2 508) receiving a DCI with an UL scheduling grant, may poll the MAC layer 510 for filling the associated transport block.

[0046] The resulting UE architecture and protocol stack structure is presented in FIG. 5 (as IIoT Device 504) in comparison to a multi-UE device solution (as IIoT Device 502). Shown also in FIG. 5 are layers SDAP 514, RRC 516, PDCP 518, and RLC 520 within the UE-CU 506. As also shown in FIG. 5, user plane and control plane functionality is provided in UE-CU 506.

[0047] The resulting architecture is similar to the UE being equipped with several Rx/Tx chains. However, UEs equipped with separate Tx/Rx chains are never fully independent as they are subject to certain limitations due to being physically co-located, e.g. they may interfere with each other if both operate in the same spectrum, hence degrading each other’s performance, etc. This is the main reason for which they cannot be used to connect to a single cell except when following MGMO configurations; on the contrary they can currently connect to different cells only, i.e. a PCell and a SCell/PCell in CA/DC configurations. The architecture and related examples described herein solve these limitations due to the fact that UE-DUs are separated in space, thus they experience different radio conditions and can take advantage of spatial diversity even when they are connected to the same gNB. The spatial separation can be leveraged especially when directive beamforming is adopted, removing the cross-interference between the UE-DUs to a large extent. [0048] The described split UE architecture has various implications on how the UE is configured by the network and how it operates in the network. The required modifications are described as follows. FIG. 6 shows a block diagram 600 illustrating an example UE split architecture as described herein, annotated by a summary of example UE configuration rule modifications to account for the UE split architecture.

[0049] For the network to fully take an advantage of the UE 605 being equipped with distributed Tx/Rx chains, it should be possible to provide the UE 605 with two or more separate PHY layer configurations (e.g., PHY 612 and PHY 613) - each associated with a particular UE-DU entity (also known as independent/distributed Tx/Rx chain). FIG. 6 shows two such UE-DU entities, UE-DU 1 607 and UE-DU2 608.

[0050] Once the gNB is made aware of the UE 605 implementing independent Tx/Rx chains (e.g. by means of the UE radio capabilities indication), it configures each Tx/Rx chain separately and effectively they are treated as separate UEs from the PHY layer perspective. From a higher layer perspective the UE 605 is still treated as a single entity.

[0051] The following modifications in the current RRC configuration model are introduced.

[0052] The UE 605 which is equipped with independent Tx/Rx chains indicates such capability to the gNB. In case the capabilities of each of the independent Tx/Rx chains are the same, the signaling may be a simple indication. In case the PHY capabilities of each of the chains are different (e.g. supported band combinations), then those differences may be indicated in the capability signaling; in particular, all of the PHY capabilities can be indicated by the UE 605 separately for each of its Tx/Rx chains.

[0053] Based on that indication the gNB provides separate PHY layer (e.g., PHY 612 and PHY 613) and measurement configuration for each of the UE-DUs (e.g., UE-DU1 607 and UE-DU2 608) / independent Tx/Rx chains, but a single configuration of higher layer protocols, i.e. MAC 610, RLC 620, PDCP 618, SDAP 614. In FIG. 6, each such higher layer protocol is part of UE-CU 606. RRC 616 is shown within UE-CU 606, as well. Once configured, each UE-DU (independent Tx/Rx chain), e.g., UE-DU1 607 and UE-DU1 608, operates as if it was located in a separate UE from the PHY layer perspective, e.g. it applies independent power control, TCI state control, PHY and mobility measurements, power control, Timing Advance control, data scheduling and data transmission/reception, SCell activation / deactivation, beam management, etc.

[0054] To allow for independent operation of these functions, it has to be possible to identify to which of the Tx Rx chains the control messages sent by the gNB apply to (in case both UE-DUs 607 and 608 operate under the coverage of the same gNB) and this can be realized in one of the following ways: by assigning each of the Tx/Rx chains a separate C-RNTI; and also by indicating a Tx/Rx chain ID in the control messages sent by the gNB (e.g. DCI or MAC CEs). In one embodiment, a single-DCI may control the scheduling of data in parallel to both DUs 607 and 608. At the gNB side, further processing/functionality may include identifying the data received from different DUs (e.g., 607 and 608) as belonging to the same UE 605 and forwarding it to the logical channels associated with this UE 605.

[0055] The summary of the proposed rules and required modifications are presented in FIG. 6. As shown in FIG. 6, the example configuration rule modifications may include, e.g. associated with the UE-CU 606, a single RRC connection, a single higher layer radio protocol stack, common configuration of UP protocols, common security keys, common QoS and radio bearer configurations, and common MAC layer allowing for soft-combining of packets coming from different UE-DU parts.

[0056] As further shown in FIG. 6, the example configuration rule modifications may include, e.g. associated with the UE-DU 1 607 and UE-DU2 608, separate configurations of PHY layer per UE-DU part, for example: bandwidth part and carrier aggregation configurations, control channel configurations (PDCCH, PUCCH), data channel configurations (PDSCH, PUSCH), reference signal(s) (RS) configurations, for example, CSI-RS, SSB, and DMRS.

[0057] As further shown in FIG. 6, the example configuration rule modifications may include, e.g. associated with the UE-DU1 607 and UE-DU2 608, separate measurement configuration per UE-DU part, for example: channel state information (CSI) and beam measurements and reporting, radio link monitoring and/or beam monitoring, or RRM/mobility measurements.

[0058] As is shown by the example of FIG. 6, the configurations are provided from the network to the corresponding layer of the UE. For example, any MAC configuration is provided to the MAC layer, any RRC configuration is provided to the RRC layer, and so forth. The configurations are specific per DU. For example, CSI measurements for a DU may be configured differently compared to another DU.

[0059] Such a split architecture aims at enabling a cost-efficient alternative of the multi-UE device that does not require inter-UE coordination, and particularly suited to scenarios where data duplicates are transmitted via the two or more UE-DUs (see FIG. 7).

[0060] FIG. 7 is a block diagram 700 depicting an example split UE architecture used in user plane redundancy solutions, based on the examples described herein. As shown in FIG. 7, Host A 701 includes the FRER 702 which has dual path redundancy to UE-CU 703, which in turn has dual path redundancy to UE-DU1 704 and UE-DU2 706.

[0061] In the example shown in FIG. 7, the UE-DU1 704 may be connected to one of gNBl 708 or gNB2 710, both of gNBl 708 and gNB2 710, or neither of gNBl 708 and gNB2 710. Similarly, the UE-DU2 706 may be connected to one of gNBl 708 or gNB2 710, both of gNBl 708 and gNB2 710, or neither of gNBl 708 and gNB2 710. Each gNB, namely gNBl 708 and gNB2

702 has a path to a respective UPF, namely UPF1 712 and UPF2 714, which in turn has a path to a respective switch, namely switch 716 and switch 718. The paths from switch 716 and 718 are to Host B 722, where Host B 722 includes a FRER 720.

[0062] In detail, key advantages of the described architecture include the following. Separate UE radio units (UE-DU part) allow for hardware redundancy and spatial diversity on radio interfaces including cases where (see for example FIG. 7) two UE-DUs are connected to the same gNB, two UE-DUs are connected to different gNBs, and where two UE-DUs have Dual-Connectivity established with the same pair of gNBs.

[0063] Furthermore, a single UE-CU allows use of a single control plane connection, the possibility to share security keys between multiple UE-DUs, and to dynamically switch or duplicate data over the two paths / UE-DUs. In addition, it is more cost-efficient than the multi-UE device solution while providing the same level of reliability and redundancy. In addition, the described UE split architecture does not require standardization of any coordination between the UEs in a single device or of the related interface.

[0064] FIG. 8 is another example apparatus 800, which may be implemented in hardware, configured to implement a UE split architecture with distributed Tx/Rx chains based on the examples described herein. The apparatus 800 comprises a processor 802, at least one non-transitory memory 804 including computer program code 805, wherein the at least one memory 804 and the computer program code 805 are configured to, with the at least one processor 802, cause the apparatus 800 to implement a UE split architecture with distributed Tx/Rx chains 806 based on the examples described herein. The apparatus 800 optionally includes a display 808 that may be used to display aspects of the apparatus 800 or to provide input and output (I/O). The apparatus 800 also includes one or more network (NW) interfaces (I/F(s)) 810. TheNWI/F(s) 810 may be wired and/or wireless and communicate over the Internet/other network(s) via any communication technique. The NW I/F(s) 810 may comprise one or more transmitters and one or more receivers. The apparatus 800 may be a UE, a gNB, or an IIoT device. [0065] It should also be appreciated that any or both of module 140-1 and module 140-2 of UE 110 may provide functionality to support the implementation of the methods described herein for a UE split architecture with distributed Tx/Rx chains. In some examples, the functionality for UE split architecture with distributed Tx/Rx chains may also be supported/implemented by module 150-1 and/or module 150-1 of RAN node 170, and or computer program code 173 of network element 190, for example in combination with UE 110 (e.g., module 140-1 and/or module 140-2 of UE 110).

[0066] FIG. 9 is an example method 900 for implementation of a UE split architecture with distributed Tx Rx chains. At 902, the method includes providing a central unit associated with a medium access control layer and at least one other protocol layer. At 904, the method includes providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers. At 906, the method includes providing an internal interface for each of the one or more distributed units for connection to the central unit.

[0067] FIG. 10 is an example method 1000 for implementation of a UE split architecture with distributed Tx Rx chains. At 1002, the method includes receiving an indication of independent transceiver chains implemented as independent one or more distributed units. At 1004, the method includes providing a separate physical layer and measurement configuration for each of the independent transceiver chains. At 1006, the method includes providing a single configuration of higher layer protocols. At 1008, the method includes providing at least one control message for application to the one or more distributed units.

[0068] An example apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: provide a central unit associated with a medium access control layer and at least one other protocol layer; provide one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and provide an internal interface for each of the one or more distributed units for connection to the central unit.

[0069] The apparatus may further include wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

[0070] The apparatus may further include wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving a control message with a downlink scheduling grant: determine which of the one or more distributed units the control message applies to; decode, by at least one of the one or more distributed units, an associated transport block; and provide a medium access control protocol data unit to the medium access control layer.

[0071] The apparatus may further include wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving a control message with an uplink scheduling grant: determine which of the one or more distributed units the control message applies to; instruct the medium access control layer to generate an associated transport block; and instruct the determined one or more distributed unit to transmit the generated transport block.

[0072] The apparatus may further include wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: indicate a presence and capabilities of the distributed chain of transceivers to a radio node.

[0073] The apparatus may further include wherein the indication is provided separately for each of the physical layer configurations.

[0074] The apparatus may further include wherein the central unit comprises redundant hardware.

[0075] The apparatus may further include wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

[0076] The apparatus may further include wherein the central unit implements one or more of: a single radio resource control (RJRC) connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service (QoS) and radio bearer configurations; or a common medium access control (MAC) layer allowing for soft- combining of packets coming from different of the one or more distributed units.

[0077] The apparatus may further include wherein each of the distributed units within a single user equipment (UE) is provided with (for example, from the network) or comprises a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH); data channel configurations comprising either a physical downlink shared channel (PDSCH) or a physical uplink shared channel (PUSCH); or reference signal configurations comprising either a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), or a demodulation reference signal (DMRS).

[0078] The apparatus may further include wherein the one or more distributed units is provided (for example, from the network) or comprises a measurement configuration comprising one or more of: channel state information (CSI) and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management (RRM) or mobility measurements.

[0079] The apparatus may be implemented in user plane redundancy solutions.

[0080] The apparatus may further include wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

[0081] The apparatus may be implemented within a user equipment.

[0082] The apparatus may further include wherein the user equipment is part of an industrial internet of things (IIoT) device.

[0083] An example apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: receive an indication of independent transceiver chains implemented as independent one or more distributed units; provide a separate physical layer and measurement configuration for each of the independent transceiver chains; provide a single configuration of higher layer protocols; and provide at least one control message for application to the one or more distributed units.

[0084] The apparatus may further include wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: assign each of the independent transceiver chains a separate cell radio network temporary identifier (C-RNTI).

[0085] The apparatus may further include wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: identify data received from the one or more distributed units as belonging to a same user equipment; and forward data to logical channels associated with the user equipment. [0086] The apparatus may further include wherein the at least one memoiy and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: indicate a transceiver chain identifier (ID) in the control message.

[0087] The apparatus may further include wherein the control message is downlink control information (DCI) or a medium access control (MAC) control element (CE).

[0088] The apparatus may further include wherein the higher layer protocols comprise one or more of medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), or service data adaptation protocol (SDAP).

[0089] The apparatus may further include wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

[0090] The apparatus may be implemented in user plane redundancy solutions.

[0091] The apparatus may further include wherein the at least one memoiy and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: provide connectivity to two of the distributed units; or provide connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or provide connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

[0092] An example method includes providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

[0093] The method may further include wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

[0094] The method may further include in response to receiving a control message with a downlink scheduling grant: determining which of the one or more distributed units the control message applies to; decoding, by at least one of the one or more distributed units, an associated transport block; and providing a medium access control protocol data unit to the medium access control layer. [0095] The method may further include in response to receiving a control message with an uplink scheduling grant: determining which of the one or more distributed units the control message applies to; instructing the medium access control layer to generate an associated transport block; and instructing the determined one or more distributed unit to transmit the generated transport block.

[0096] The method may further include indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

[0097] The method may further include wherein the indication is provided separately for each of the physical layer configurations.

[0098] The method may further include wherein the central unit comprises redundant hardware.

[0099] The method may further include wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

[00100] The method may further include wherein the central unit implements one or more of: a single radio resource control (RRC) connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service (QoS) and radio bearer configurations; or a common medium access control (MAC) layer allowing for soft- combining of packets coming from different of the one or more distributed units.

[00101] The method may further include wherein each of the distributed units within a single user equipment (UE) is provided with (for example, from the network) or comprises a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH); data channel configurations comprising either a physical downlink shared channel (PDSCH) or a physical uplink shared channel (PUSCH); or reference signal configurations comprising either a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), or a demodulation reference signal (DMRS).

[00102] The method may further include wherein the one or more distributed units is provided (for example, from the network) or comprises a measurement configuration comprising one or more of: channel state information (CSI) and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management (REM) or mobility measurements.

[00103] The method may be implemented in user plane redundancy solutions. [00104] The method may further include wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

[00105] The method may be implemented within a user equipment.

[00106] The method may further include wherein the user equipment is part of an industrial internet of things (IIoT) device.

[00107] An example method includes receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

[00108] The method may further include assigning each of the independent transceiver chains a separate cell radio network temporary identifier (C-R TI).

[00109] The method may further include identifying data received from the one or more distributed units as belonging to a same user equipment; and forwarding data to logical channels associated with the user equipment.

[00110] The method may further include indicating a transceiver chain identifier (ID) in the control message.

[00111] The method may further include wherein the control message is downlink control information (DCI) or a medium access control (MAC) control element (CE).

[00112] The method may further include wherein the higher layer protocols comprise one or more of medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), or service data adaptation protocol (SDAP).

[00113] The method may further include wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

[00114] The method may be implemented in user plane redundancy solutions.

[00115] The method may further include providing connectivity to two of the distributed units; or providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

[00116] An example non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations may be provided, the operations comprising: providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

[00117] The non-transitory program storage may further include wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

[00118] The non-transitory program storage may further include operations comprising: in response to receiving a control message with a downlink scheduling grant: determining which of the one or more distributed units the control message applies to; decoding, by at least one of the one or more distributed units, an associated transport block; and providing a medium access control protocol data unit to the medium access control layer.

[00119] The non-transitory program storage may further include operations comprising: in response to receiving a control message with an uplink scheduling grant: determining which of the one or more distributed units the control message applies to; instructing the medium access control layer to generate an associated transport block; and instructing the determined one or more distributed unit to transmit the generated transport block.

[00120] The non-transitory program storage may further include operations comprising: indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

[00121] The non-transitory program storage may further include wherein the indication is provided separately for each of the physical layer configurations.

[00122] The non-transitory program storage may further include wherein the central unit comprises redundant hardware.

[00123] The non-transitory program storage may further include wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective. [00124] The non-transitory program storage may further include wherein the central unit implements one or more of: a single radio resource control (RRC) connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service (QoS) and radio bearer configurations; or a common medium access control (MAC) layer allowing for soft-combining of packets coming from different of the one or more distributed units.

[00125] The non-transitory program storage may further include wherein each of the distributed units within a single user equipment (UE) is provided with (for example, from the network) or comprises a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH); data channel configurations comprising either a physical downlink shared channel (PDSCH) or a physical uplink shared channel (PUSCH); or reference signal configurations comprising either a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), or a demodulation reference signal (DMRS).

[00126] The non-transitory program storage may further include wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information (CSI)) and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management (RRM) or mobility measurements.

[00127] The non-transitory program storage may be implemented in user plane redundancy solutions.

[00128] The non-transitory program storage may further include wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

[00129] The non-transitory program storage may further be implemented within a user equipment.

[00130] The non-transitory program storage may further include wherein the user equipment is part of an industrial internet of things (IIoT) device.

[00131] An example non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations may be provided, the operations comprising: receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

[00132] The non-transitory program storage device may further include operations comprising assigning each of the independent transceiver chains a separate cell radio network temporary identifier (C-RNTI).

[00133] The non-transitory program storage device may further include operations comprising: identifying data received from the one or more distributed units as belonging to a same user equipment; and forwarding data to logical channels associated with the user equipment.

[00134] The non-transitory program storage device may further include operations comprising indicating a transceiver chain identifier (ID) in the control message.

[00135] The non-transitory program storage device may further include wherein the control message is downlink control information (DCI) or a medium access control (MAC) control element (CE).

[00136] The non-transitory program storage device may further include wherein the higher layer protocols comprise one or more of medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), or service data adaption protocol (SDAP).

[00137] The non-transitory program storage device may further include wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

[00138] The non-transitory program storage device may be implemented in user plane redundancy solutions.

[00139] The non-transitory program storage device may further include operations comprising: providing connectivity to two of the distributed units; or providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

[00140] An example apparatus includes means for providing a central unit associated with a medium access control layer and at least one other protocol layer; means for providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and means for providing an internal interface for each of the one or more distributed units for connection to the central unit.

[00141] The apparatus may further include wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

[00142] The apparatus may further include, in response to receiving a control message with a downlink scheduling grant: means for determining which of the one or more distributed units the control message applies to; means for decoding, by at least one of the one or more distributed units, an associated transport block; and means for providing a medium access control protocol data unit to the medium access control layer.

[00143] The apparatus may further include, in response to receiving a control message with an uplink scheduling grant: means for determining which of the one or more distributed units the control message applies to; means for instructing the medium access control layer to generate an associated transport block; and means for instructing the determined one or more distributed unit to transmit the generated transport block.

[00144] The apparatus may further include means for indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

[00145] The apparatus may further include wherein the indication is provided separately for each of the physical layer configurations.

[00146] The apparatus may further include wherein the central unit comprises redundant hardware.

[00147] The apparatus may further include wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

[00148] The apparatus may further include wherein the central unit implements one or more of: a single radio resource control (RRC) connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service (QoS) and radio bearer configurations; or a common medium access control layer allowing for soft-combining of packets coming from different of the one or more distributed units.

[00149] The apparatus may further include wherein each of the distributed units within a single user equipment (UE) is provided with (for example, from the network) or comprises a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH); data channel configurations comprising either a physical downlink shared channel (PDSCH) or a physical uplink shared channel (PUSCH); or reference signal configurations comprising either a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), or a demodulation reference signal (DMRS).

[00150] The apparatus may further include wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information (CSI) and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management (RRM) or mobility measurements.

[00151] The apparatus may be implemented in user plane redundancy solutions.

[00152] The apparatus may further include wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

[00153] The apparatus may be implemented within a user equipment.

[00154] The apparatus may further include wherein the user equipment is part of an industrial internet of things (IIoT) device.

[00155] An example apparatus includes means for receiving an indication of independent transceiver chains implemented as independent one or more distributed units; means for providing a separate physical layer and measurement configuration for each of the independent transceiver chains; means for providing a single configuration of higher layer protocols; and means for providing at least one control message for application to the one or more distributed units.

[00156] The apparatus may further include means for assigning each of the independent transceiver chains a separate cell radio network temporary identifier (C-RNTI).

[00157] The apparatus may further include means for identifying data received from the one or more distributed units as belonging to a same user equipment; and means for forwarding data to logical channels associated with the user equipment.

[00158] The apparatus may further include means for indicating a transceiver chain identifier in the control message. [00159] The apparatus may further include wherein the control message is downlink control information or a medium access control (MAC) control element (CE).

[00160] The apparatus may further include wherein the higher layer protocols comprise one or more of medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), or service data adaption protocol (SDAP).

[00161] The apparatus may further include wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

[00162] The apparatus may be implemented in user plane redundancy solutions.

[00163] The apparatus may further include means for providing connectivity to two of the distributed units; or means for providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or means for providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

[00164] An example network may include at least one apparatus, wherein the apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: provide a central unit associated with a medium access control layer and at least one other protocol layer; provide one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and provide an internal interface for each of the one or more distributed units for connection to the central unit.

[00165] An example network may include at least one apparatus, wherein the apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: receive an indication of independent transceiver chains implemented as independent one or more distributed units; provide a separate physical layer and measurement configuration for each of the independent transceiver chains; provide a single configuration of higher layer protocols; and provide at least one control message for application to the one or more distributed units.

[00166] An example network may include at least one apparatus, wherein the apparatus includes means for providing a central unit associated with a medium access control layer and at least one other protocol layer; means for providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and means for providing an internal interface for each of the one or more distributed units for connection to the central unit.

[00167] An example network may include at least one apparatus, wherein the apparatus includes means for receiving an indication of independent transceiver chains implemented as independent one or more distributed units; means for providing a separate physical layer and measurement configuration for each of the independent transceiver chains; means for providing a single configuration of higher layer protocols; and means for providing at least one control message for application to the one or more distributed units.

[00168] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

[00169] The following acronyms and abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3 GPP third generation partnership project

5G fifth generation

5GC 5G core network

AMF access and mobility [management] function

CA carrier aggregation

CE control element

CP control plane

C-RNTI cell radio network temporary identifier

CSI channel state indicator/information

CSI-RS channel state information - reference signal

CU centralized unit or central unit

DAS distributed antenna systems

DC dual connectivity

DCI downlink control information

DL downlink

DMRS demodulation reference signal(s) DU distributed unit

DSP digital signal processor

E2E end-to-end eNB (or eNodeB) evolved node b (e.g., an LTE base station) EN-DC E-UTRA-NR dual connectivity en-gNB or En-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as secondary node in EN-DC

E-UTRA evolved universal terrestrial radio access, i.e., the LTE radio access technology

FI functional split interface in 3 GPP between the CU and the DU

Fl-C FI control plane interface

Fl-U FI user plane interface

FRER frame replication and elimination for reliability (part of IEEE TSN standard) gNB (or gNodeB) base station for 5G/NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC; or 5G Node B gNB-RU gNB remote unit

ID identifier

IEEE Institute of Electrical and Electronics Engineers

I/F interface

I/O input and output

IIoT industrial internet of things

LTE long term evolution

MAC medium access control

MIMO multiple-input/multiple-output

MME mobility management entity multi-TRP multiple transmission and reception ng or NG new generation

NG-C NG control plane interface ng-eNB or NG-eNB new generation eNB

NG-U NG user plane interface

NR orNR- new radio

N/W or NW network

PCell primary cell

PDA personal digital assistant PDCCH physical downlink control channel

PDCP packet data convergence protocol

PDSCH physical downlink shared channel

PDU protocol data unit

PHY physical layer

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

QoS quality of service

RAN radio access network

Rel- release

RLC radio link control

RRC radio resource control

RRH remote radio head

RRM radio resource management

RS reference signal

RU radio unit

Rx receiver

SA2 service and system aspects working group 2

SCell secondary cell

SDAP service data adaptation protocol

SGW serving gateway

SMF session management function

SSB synchronization signal block

TCI transmission configuration indication

TR technical report

TRP transmission and reception point

TS technical specification

TSN time sensitive network(ing)

Tx transmitter

Tx/Rx or Rx/Tx transmission/reception, transceiver

UE user equipment (e.g., a wireless, typically mobile device)

UL uplink

UP user plane

UPF user plane function

URLLC ultra-reliable low-latency communications

WG working group Xn-C Xn control plane interface defined between two NG-RAN nodes

Xn-U Xn user plane interface defined between two NG-RAN nodes

Claims

CLAIMS What is claimed is:

1. An apparatus comprising: at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: provide a central unit associated with a medium access control layer and at least one other protocol layer; provide one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and provide an internal interface for each of the one or more distributed units for connection to the central unit.

2. The apparatus of claim 1, wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

3. The apparatus of any one of claims 1 to 2, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving a control message with a downlink scheduling grant: determine which of the one or more distributed units the control message applies to; decode, by at least one of the one or more distributed units, an associated transport block; and provide a medium access control protocol data unit to the medium access control layer.

4. The apparatus of any one of claims 1 to 3, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving a control message with an uplink scheduling grant: determine which of the one or more distributed units the control message applies to; instruct the medium access control layer to generate an associated transport block; and instruct the determined one or more distributed unit to transmit the generated transport block.

5. The apparatus of any one of claims 1 to 4, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: indicate a presence and capabilities of the distributed chain of transceivers to a radio node.

6. The apparatus of claim 5, wherein the indication is provided separately for each of the physical layer configurations.

7. The apparatus of any one of claims 1 to 6, wherein the central unit comprises redundant hardware.

8. The apparatus of any one of claims 1 to 7, wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

9. The apparatus of any one of claims 1 to 8, wherein the central unit implements one or more of: a single radio resource control connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service and radio bearer configurations; or a common medium access control layer allowing for soft-combining of packets coming from different of the one or more distributed units.

10. The apparatus of any one of claims 1 to 9, wherein each of the distributed units within a single user equipment is provided with a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel or a physical uplink control channel; data channel configurations comprising either a physical downlink shared channel or a physical uplink shared channel; or reference signal configurations comprising either a channel state information reference signal, a synchronization signal block, or a demodulation reference signal.

11. The apparatus of any one of claims 1 to 10, wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management or mobility measurements.

12. The apparatus of any one of claims 1 to 11, implemented in user plane redundancy solutions.

13. The apparatus of claim 12, wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

14. The apparatus of any one of claims 1 to 13, implemented within a user equipment.

15. The apparatus of claim 14, wherein the user equipment is part of an industrial internet of things device.

16. An apparatus comprising: at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: receive an indication of independent transceiver chains implemented as independent one or more distributed units; provide a separate physical layer and measurement configuration for each of the independent transceiver chains; provide a single configuration of higher layer protocols; and provide at least one control message for application to the one or more distributed units.

17. The apparatus of claim 16, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: assign each of the independent transceiver chains a separate cell radio network temporary identifier.

18. The apparatus of any one of claims 16 to 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: identify data received from the one or more distributed units as belonging to a same user equipment; and forward data to logical channels associated with the user equipment.

19. The apparatus of any one of claims 16 to 18, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: indicate a transceiver chain identifier in the control message.

20. The apparatus of any one of claims 16 to 19, wherein the control message is downlink control information or a medium access control control element.

21. The apparatus of any one of claims 16 to 20, wherein the higher layer protocols comprise one or more of medium access control, radio link control, packet data convergence protocol, or service data adaption protocol.

22. The apparatus of any one of claims 16 to 21, wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

23. The apparatus of any one of claims 16 to 22, implemented in user plane redundancy solutions.

24. The apparatus of claim 23, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform: provide connectivity to two of the distributed units; or provide connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or provide connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

25. A method comprising: providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

26. The method of claim 25, wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

27. The method of any one of claims 25 to 26, further comprising: in response to receiving a control message with a downlink scheduling grant: determining which of the one or more distributed units the control message applies to; decoding, by at least one of the one or more distributed units, an associated transport block; and providing a medium access control protocol data unit to the medium access control layer.

28. The method of any one of claim 25 to 27, further comprising: in response to receiving a control message with an uplink scheduling grant: determining which of the one or more distributed units the control message applies to; instructing the medium access control layer to generate an associated transport block; and instructing the determined one or more distributed unit to transmit the generated transport block.

29. The method of any one of claims 25 to 28, further comprising: indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

30. The method of claim 29, wherein the indication is provided separately for each of the physical layer configurations.

31. The method of any one of claims 25 to 30, wherein the central unit comprises redundant hardware.

32. The method of any one of claims 25 to 31 , wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

33. The method of any one of claims 25 to 32, wherein the central unit implements one or more of: a single radio resource control connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service and radio bearer configurations; or a common medium access control layer allowing for soft-combining of packets coming from different of the one or more distributed units.

34. The method of any one of claims 25 to 33, wherein each of the distributed units within a single user equipment is provided with a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel or a physical uplink control channel; data channel configurations comprising either a physical downlink shared channel or a physical uplink shared channel; or reference signal configurations comprising either a channel state information reference signal, a synchronization signal block, or a demodulation reference signal.

35. The method of any one of claims 25 to 34, wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management or mobility measurements.

36. The apparatus of any one of claims 25 to 35, implemented in user plane redundancy solutions.

37. The method of claim 36, wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

38. The method of any one of claims 25 to 37, implemented within a user equipment.

39. The method of claim 38, wherein the user equipment is part of an industrial internet of things device.

40. A method comprising: receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

41. The method of claim 40, further comprising assigning each of the independent transceiver chains a separate cell radio network temporary identifier.

42. The method of any one of claims 40 to 41, further comprising: identifying data received from the one or more distributed units as belonging to a same user equipment; and forwarding data to logical channels associated with the user equipment.

43. The method of any one of claims 40 to 42, further comprising indicating a transceiver chain identifier in the control message.

44. The method of any one of claims 40 to 43, wherein the control message is downlink control information or a medium access control control element.

45. The method of any one of claims 40 to 44, wherein the higher layer protocols comprise one or more of medium access control, radio link control, packet data convergence protocol, or service data adaption protocol.

46. The method of any one of claims 40 to 45, wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

47. The method of any one of claims 40 to 46, implemented in user plane redundancy solutions.

48. The method of claim 47, further comprising: providing connectivity to two of the distributed units; or providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

49. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: providing a central unit associated with a medium access control layer and at least one other protocol layer; providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and providing an internal interface for each of the one or more distributed units for connection to the central unit.

50. The non-transitory program storage device of claim 49, wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

51. The non-transitory program storage device of any one of claims 49 to 50, further comprising: in response to receiving a control message with a downlink scheduling grant: determining which of the one or more distributed units the control message applies to; decoding, by at least one of the one or more distributed units, an associated transport block; and providing a medium access control protocol data unit to the medium access control layer.

52. The non-transitory program storage device of any one of claim 49 to 51, the operations further comprising: in response to receiving a control message with an uplink scheduling grant: determining which of the one or more distributed units the control message applies to; instructing the medium access control layer to generate an associated transport block; and instructing the determined one or more distributed unit to transmit the generated transport block.

53. The non-transitory program storage device of any one of claims 49 to 52, the operations further comprising: indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

54. The non-transitory program storage device of claim 53, wherein the indication is provided separately for each of the physical layer configurations.

55. The non-transitory program storage device of any one of claims 49 to 54, wherein the central unit comprises redundant hardware.

56. The non-transitory program storage device of any one of claims 49 to 55, wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

57. The non-transitory program storage device of any one of claims 49 to 56, wherein the central unit implements one or more of: a single radio resource control connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service and radio bearer configurations; or a common medium access control layer allowing for soft-combining of packets coming from different of the one or more distributed units.

58. The non-transitory program storage device of any one of claims 49 to 57, wherein each of the distributed units within a single user equipment is provided with a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel or a physical uplink control channel; data channel configurations comprising either a physical downlink shared channel or a physical uplink shared channel; or reference signal configurations comprising either a channel state information reference signal, a synchronization signal block, or a demodulation reference signal.

59. The non-transitory program storage device of any one of claims 49 to 58, wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management or mobility measurements.

60. The non-transitory program storage device of any one of claims 49 to 59, implemented in user plane redundancy solutions.

61. The non-transitory program storage device of claim 60, wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

62. The non-transitory program storage device of any one of claims 49 to 61, implemented within a user equipment.

63. The non-transitory program storage device of claim 62, wherein the user equipment is part of an industrial internet of things device.

64. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: receiving an indication of independent transceiver chains implemented as independent one or more distributed units; providing a separate physical layer and measurement configuration for each of the independent transceiver chains; providing a single configuration of higher layer protocols; and providing at least one control message for application to the one or more distributed units.

65. The non-transitory program storage device of claim 64, the operations further comprising assigning each of the independent transceiver chains a separate cell radio network temporary identifier.

66. The non-transitory program storage device of any one of claims 64 to 65, the operations further comprising: identifying data received from the one or more distributed units as belonging to a same user equipment; and forwarding data to logical channels associated with the user equipment.

67. The non-transitory program storage device of any one of claims 64 to 66, the operations further comprising indicating a transceiver chain identifier in the control message.

68. The non-transitory program storage device of any one of claims 64 to 67, wherein the control message is downlink control information or a medium access control control element.

69. The non-transitory program storage device of any one of claims 64 to 68, wherein the higher layer protocols comprise one or more of medium access control, radio link control, packet data convergence protocol, or service data adaption protocol.

70. The non-transitory program storage device of any one of claims 64 to 69, wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

71. The non-transitory program storage device of any one of claims 64 to 70, implemented in user plane redundancy solutions.

72. The non-transitory program storage device of claim 71, the operations further comprising: providing connectivity to two of the distributed units; or providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

73. An apparatus comprising: means for providing a central unit associated with a medium access control layer and at least one other protocol layer; means for providing one or more distributed units each associated with a respective physical layer, wherein the one or more distributed units and respective physical layer provide a chain of distributed transceivers; and means for providing an internal interface for each of the one or more distributed units for connection to the central unit.

74. The apparatus of claim 73, wherein the one or more distributed units are physically distributed and separated so as to experience different radio conditions.

75. The apparatus of any one of claims 73 to 74, further comprising: in response to receiving a control message with a downlink scheduling grant: means for determining which of the one or more distributed units the control message applies to; means for decoding, by at least one of the one or more distributed units, an associated transport block; and means for providing a medium access control protocol data unit to the medium access control layer.

76. The apparatus of any one of claim 73 to 75, further comprising: in response to receiving a control message with an uplink scheduling grant: means for determining which of the one or more distributed units the control message applies to; means for instructing the medium access control layer to generate an associated transport block; and means for instructing the determined one or more distributed unit to transmit the generated transport block.

77. The apparatus of any one of claims 73 to 76, further comprising: means for indicating a presence and capabilities of the distributed chain of transceivers to a radio node.

78. The apparatus of claim 77, wherein the indication is provided separately for each of the physical layer configurations.

79. The apparatus of any one of claims 73 to 78, wherein the central unit comprises redundant hardware.

80. The apparatus of any one of claims 73 to 79, wherein the one or more distributed units operates as if it was located in a separate user equipment from a physical layer perspective.

81. The apparatus of any one of claims 73 to 80, wherein the central unit implements one or more of: a single radio resource control connection; a single higher layer protocol stack; a common configuration of user plane protocols; common security keys; common quality of service and radio bearer configurations; or a common medium access control layer allowing for soft-combining of packets coming from different of the one or more distributed units.

82. The apparatus of any one of claims 73 to 81, wherein each of the distributed units within a single user equipment is provided with a separate physical layer configuration comprising one or more of: bandwidth part and carrier aggregation configurations; control channel configurations comprising either a physical downlink control channel or a physical uplink control channel; data channel configurations comprising either a physical downlink shared channel or a physical uplink shared channel; or reference signal configurations comprising either a channel state information reference signal, a synchronization signal block, or a demodulation reference signal.

83. The apparatus of any one of claims 73 to 82, wherein the one or more distributed units is provided a measurement configuration comprising one or more of: channel state information and beam measurements and reporting; radio link monitoring or beam monitoring; or radio resource management or mobility measurements.

84. The apparatus of any one of claims 73 to 63, implemented in user plane redundancy solutions.

85. The apparatus of claim 84, wherein: two of the distributed units are connected to a common radio node; or the two of the distributed units are connected to different radio nodes; or the two of the distributed units have dual connectivity established with a pair of radio nodes.

86. The apparatus of any one of claims 73 to 85, implemented within a user equipment.

87. The apparatus of claim 86, wherein the user equipment is part of an industrial internet of things device.

88. An apparatus comprising: means for receiving an indication of independent transceiver chains implemented as independent one or more distributed units; means for providing a separate physical layer and measurement configuration for each of the independent transceiver chains; means for providing a single configuration of higher layer protocols; and means for providing at least one control message for application to the one or more distributed units.

89. The apparatus of claim 88, further comprising means for assigning each of the independent transceiver chains a separate cell radio network temporary identifier.

90. The apparatus of any one of claims 88 to 89, further comprising: means for identifying data received from the one or more distributed units as belonging to a same user equipment; and means for forwarding data to logical channels associated with the user equipment.

91. The apparatus of any one of claims 88 to 90, further comprising means for indicating a transceiver chain identifier in the control message.

92. The apparatus of any one of claims 88 to 91, wherein the control message is downlink control information or a medium access control control element.

93. The apparatus of any one of claims 88 to 92, wherein the higher layer protocols comprise one or more of medium access control, radio link control, packet data convergence protocol, or service data adaption protocol.

94. The apparatus of any one of claims 88 to 93, wherein the at least one control message controls scheduling of data in parallel to the one or more distributed units.

95. The apparatus of any one of claims 88 to 94, implemented in user plane redundancy solutions.

96. The apparatus of claim 95, further comprising: means for providing connectivity to two of the distributed units; or means for providing connectivity to one of the distributed units while at least one other distributed unit is connected to at least one other radio node; or means for providing connectivity to the two of the distributed units while the two of the distributed units have dual connectivity with the at least one other radio node.

97. A network comprising at least one apparatus of claim 1.

98. A network comprising at least one apparatus of claim 16.

97. A network comprising at least one apparatus of claim 73.

98. A network comprising at least one apparatus of claim 88.