Patent Description:
Examples of such multiple-access systems include fourth generation (<NUM>) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (<NUM>) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM).

A base station may employ a wireline link to communicate with neighboring base stations to coordinate backhaul or fronthaul transmissions. Some wireless communications systems (e.g., millimeter wave (mmW) communications systems) may deploy a large number of densely-spaced base stations. In some systems, such as systems with relatively densely spaced base stations, base stations may use wireless backhaul or fronthaul links (e.g., relay nodes) for backhaul or fronthaul communications in addition to or instead of wireline links.

<CIT> relates to a mobile communication system using Relay Nodes (RNs) where RNs provide the same functionality as conventional base stations and whose link to the network is provided using a similar radio interface as used by the mobile devices that connect to the base station.

Further, <CIT> relates to wireless communication system that comprises the relay station, a base station, and a core network. The relay station is wirelessly connected to the base station, while the base station is wiredly connected to the core network. The relay station comprises a processing unit and a transceiver. The processing unit is configured to create a radio link having a control plane connection between the relay station and the base station and create a backhaul link between the relay station and the base station by the control plane connection of the radio link. The transceiver is configured to transmit a backhaul control message to the core network via the backhaul link.

In the following, the present invention is described. Particularly, the invention is defined in the independent claims. In the following, the parts of the description and drawings referring to aspects which are not covered by the claims are not presented as aspects of the invention but as background art or examples useful for understanding the invention.

The described techniques relate to improved methods, systems, devices, or apparatuses that support techniques for providing radio resource control and fronthaul control on a wireless fronthaul link. Generally, the described techniques provide for transmitting different sets of control messages through a relay to a central unit (CU) and a core network of a wireless communications system. The different sets of control messages may include a first set of control messages for an access radio link between the relay and the CU and a second set of control messages for a fronthaul configuration between a distributed unit (DU) and the CU. Various techniques are disclosed for transmitting both sets of control messages using one or more radio bearers (RBs) that are established between the relay and a DU or CU.

Such techniques may include, for example, establishing one or more radio bearers, such as multiple signaling radio bearers (SRBs) or data radio bearers (DRBs) that may carry the control messages as well as access messages between a relay and a CU. In some cases, separate SRBs may be established for different sets of control messages. In some cases, a SRB may be established for a first set of control messages, and a DRB may be established for a second set of control messages. In some cases, a SRB may be established and configured with a lower portion and an upper portion, where the lower portion multiplexes a first set of control messages encapsulated in the upper portion and a second set of control messages. In still further cases, messages of the second set of messages may be encapsulated into the first set of messages and transmitted using a SRB.

Methods for a base station relay node related to three alternative methods are described in claims <NUM>, <NUM> and <NUM>. Three corresponding apparatuses are described in claims <NUM>, <NUM> and <NUM> and a computer program product is described in claim <NUM>.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the multiplexing further comprises setting a multiplexing field to indicate whether a lower portion of the SRB includes an upper portion of the SRB or a second set of control messages. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the lower portion of the SRB may be terminated at a DU and the upper portion of the SRB may be tunneled through the DU directly to the CU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the configuring the upper portion of the SRB further comprises receiving a configuration for a first upper portion of the SRB and a second upper portion of the SRB, the first upper portion for radio resource control (RRC) messages for the access link and the second upper portion for control messages associated with the DU, and the first upper portion of the SRB and the second upper portion of the SRB are multiplexed with the lower portion of the SRB.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for establishing a second SRB with the CU. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving a configuration for the upper portion of the first SRB and the lower portion of the first SRB over the second SRB.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, a first DU supports a user equipment function (UEF) (e.g., a mobile termination function (MTF)) and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the access radio link may be established between a UEF and the CU, and the first set of control messages may be exchanged between the UEF and the CU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the second set of control messages may be fronthaul control protocol messages and the first set of control messages may be RRC protocol messages. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first set of control messages configure the lower portion of the SRB. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first set of
control messages configure the lower portion and the upper portion of the SRB for the fronthaul radio link.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for establishing a second SRB with the CU. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving a configuration for the first SRB over the second SRB.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, a first DU supports a UEF and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the access radio link may be established between a UEF and the CU, and the first set of control messages may be exchanged between the UEF and the CU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the second set of control messages may be fronthaul control protocol messages and the first set of control messages may be RRC protocol messages. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first set of control messages configure a lower portion of the SRB. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first RB comprises a first SRB with the CU and the second RB comprises a second SRB with the CU.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first RB comprises a first SRB for exchanging RRC messages with the CU, and the second RB comprises a first data radio bearer (DRB) for exchanging fronthaul control messages with the CU. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for establishing a second DRB with the CU for exchanging data packets with the CU.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for establishing a third RB with the CU. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving a configuration for the first RB and the second RB over the third RB.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, a first DU supports a UEF and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the access radio link may be established between a DU and the CU, and the first set of control messages may be exchanged between the DU and the CU. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the second set of control messages may be fronthaul control protocol messages and the first set of control messages may be RRC protocol messages.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first set of control messages configure a lower portion of a SRB. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link.

Various wireless communications systems as described herein may provide for transmitting different sets of control messages in systems that use self-backhauling or integrated access/backhaul (IAB) through a relay to a central unit (CU) and a core network of a wireless communications system. The different sets of control messages may include a first set of control messages for an access radio link between the relay and the CU and a second set of control messages for a fronthaul radio link between the relay and the CU. Various techniques are disclosed for transmitting both sets of control messages using one or more radio bearers (RBs) that are established between the relay and a distributed unit (DU) or CU.

Wireless communications systems may use various different techniques for communications, and in some systems, such as <NUM> or NR systems, directional communications (e.g., millimeter wave (mmW) transmissions) may be established between wireless nodes (e.g., a base station or a user equipment (UE)). Directional transmissions may be used to support, for example, access traffic between an access node and a UE, or backhaul traffic between access nodes. Some systems, such as relatively dense deployments of mmW base stations, may provide only a subset of the access nodes with a wireline connection, and other access nodes may have a wireless backhaul connection with one or more of the subset of the access nodes with the wireline connection, which may be referred to as self-backhauling or IAB. Self-backhauling or IAB may share wireless resources between access traffic and backhaul traffic, and may have benefits of enhancing wireless link capacity, reducing latency, reducing the cost of cell deployment, or any combination thereof. In systems with mmW base station deployments, IAB may use relatively narrow beams, which may be referred to as pencil beams, for wireless backhaul links between base stations which can help reduce inter-link interference with one or more other directional communications links in the system.

In some deployments, <NUM> or NR systems may use such DUs and CUs in a centralized radio access network (C-RAN) in which an access node or base station may be split into a DU, which resides at the network edge, and a CU, which resides in the cloud. The interface between DU and CU may be referred to as the F1 interface. In some cases, the CU/DU split architecture may be used for wireless multi-hop self-backhauling and IAB. For example, self-backhauling or IAB may provide benefits to deployments having densely spaced base stations, such as mmW deployments. When using a CU/DU architecture for IAB, one or more relays may relay access date, backhaul data, or combinations thereof between a UE or another relay to a CU (either directly or through another relay). Each relay may be configured with a UE-function (UEF) (e.g., a mobile termination function (MTF)) and DU function (DU-F), and may use the UEF to connect to a parent relay's DU, and use the DU-F to have UEs or child relays connect to itself. For this purpose, each relay's DU-F may establish a control plane connection (which may be referred to as a F1-C connection) with the CU, and each relay's UEF may establish a radio resource control (RRC) connection with the CU. Various aspects of the present disclosure provide techniques for a relay to multiplex or otherwise transmit these two C-plane (e.g., control plane) connections.

Such techniques may include, for example, establishing one or more radio bearers, such as multiple signaling radio bearers (SRBs) or data radio bearers (DRBs) that may carry the control messages as well as access messages between a relay and a CU. In some cases, separate SRBs may be established for different sets of control messages. In some cases, a SRB may be established for a first set of control messages, and a DRB may be established for a second set of control messages. In some cases, a SRB may be established and configured with a lower portion and an upper portion, the lower portion for transmission of at least a portion of the first set of control messages and a portion of a second set of control messages, and the upper portion for transmission of at least a portion of the first set of control messages, and the upper portion of the SRB and the second set of control messages may be multiplexed. In still further cases, messages of the second set of messages may be encapsulated into the first set of messages and transmitted using a SRB.

Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to techniques for providing radio resource control and fronthaul control on a wireless fronthaul link.

<FIG> illustrates an example of a wireless communication system <NUM> in accordance with various aspects of the present disclosure. The wireless communication system <NUM> includes base stations <NUM>, UEs <NUM>, and a core network <NUM>. In some examples, the wireless communication system <NUM> may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, or a New Radio (NR) network. In some cases, wireless communication system <NUM> may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices. One or more of the base stations <NUM> may serve as an access node that in some cases may include a CU, a DU, and a relay.

Base stations <NUM> may wirelessly communicate with UEs <NUM> or one or more other base stations <NUM> via one or more base station antennas. Wireless communication system <NUM> may include base stations <NUM> of different types (e.g., macro or small cell base stations).

Communication links <NUM> shown in wireless communication system <NUM> may include uplink transmissions from a UE <NUM> to a base station <NUM>, or downlink transmissions, from a base station <NUM> to a UE <NUM>.

The wireless communication system <NUM> may include, for example, a heterogeneous LTE/LTE-A or NR network in which different types of base stations <NUM> provide coverage for various geographic coverage areas <NUM>.

UEs <NUM> may be dispersed throughout the wireless communication system <NUM>, and each UE <NUM> may be stationary or mobile.

Backhaul links <NUM> may be wireline links or wireless links, as will be discussed in more detail below.

Each access network entity may communicate with UEs <NUM> through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, a transmission/reception point (TRP), or a DU. In some configurations, various functions of each access network entity or base station <NUM> may be distributed across various network devices (e.g., radio heads and access network controllers or CUs and DUs) or consolidated into a single network device (e.g., a base station <NUM>).

Wireless communication system <NUM> may operate using one or more frequency bands, typically in the range of <NUM> to <NUM>.

Wireless communication system <NUM> may also operate in a super high frequency (SHF) region using frequency bands from <NUM> to <NUM>, also known as the centimeter band.

Wireless communication system <NUM> may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from <NUM> to <NUM>), also known as the millimeter band. In some examples, wireless communication system <NUM> may support mmW communications between UEs <NUM> and base stations <NUM>, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. The propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions, which may lead to relatively dense deployments in systems that use mmW.

For example, wireless communication system may use a transmission scheme between a transmitting device (e.g., a base station <NUM>) and a receiving device (e.g., a UE <NUM>), where the transmitting device is equipped with multiple antennas and the receiving devices are equipped with one or more antennas.

In one example, a base station <NUM> may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM> or another base station <NUM>. For instance, some signals (e.g. synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station <NUM> multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by the base station <NUM> or a receiving device, such as a UE <NUM>) a beam direction for subsequent transmission and/or reception by the base station <NUM>. Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station <NUM> in a single beam direction (e.g., a direction associated with the receiving device, such as a UE <NUM>). In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions.

A receiving device (e.g., a UE <NUM> or a base station <NUM>, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals, such as synchronization signals, reference signals, beam selection signals, or other control signals.

Devices of the wireless communication system <NUM> (e.g., base stations <NUM> or UEs <NUM>) may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communication system <NUM> may include base stations <NUM> and/or UEs that can support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications systems such as an NR system may utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. In some cases, flexible symbol durations and subcarrier spacing may allow for the use of carriers across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across frequency) and horizontal (e.g., across time) sharing of resources.

In various examples as described herein some base stations <NUM> may use wireless backhauling for a backhaul link <NUM>, and in some cases may transmit different sets of control messages associated with access links and backhaul links through a relay to a CU and core network <NUM>. As will be discussed in more detail below, the different sets of control messages may include a first set of control messages for an access radio link between the relay and the CU and a second set of control messages for a fronthaul radio link between the relay and the CU. Various techniques are disclosed for transmitting both sets of control messages using one or more RBs that are established between the relay and a DU or CU.

<FIG> illustrates an example of a wireless communication system <NUM> with integrated access and backhaul that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, wireless communication system <NUM> may implement aspects of wireless communication system <NUM>. Wireless communication system <NUM> may include a number of cells <NUM> that may communicate with each other over wireless links <NUM> via base stations <NUM>. That is, wireless communication system <NUM> may include wireline backhaul link <NUM>, in addition to several relay nodes (e.g., base stations <NUM>) such that cells <NUM> may be connected via wireless links <NUM>. Wireless links <NUM> (e.g., wireless backhaul links, fronthaul links, access links, etc.) may be associated with a same or different set of wireless resources (e.g., time resources, frequency resources, code resources, spatial resources, etc.). Base stations <NUM> may further communicate with UEs <NUM> via direct wireless links <NUM>. Wireless communication system <NUM> may support the coordination of direct communications links between different nodes (e.g., UEs <NUM>, base stations <NUM>, or any combination thereof) in the wireless communication system <NUM>, and an access node may configure such direct communications links.

In the example of <FIG>, base stations <NUM> may be access nodes, and one access node, base station <NUM>-c in this example, is supported with a wireline backhaul, such as a high capacity fiber backhaul connection to a core network. Other base stations <NUM> may be connected to base station <NUM>-c with a backhaul wireless link <NUM>. In some cases, the backhaul wireless links <NUM> or direct wireless links <NUM> may use pencil beams that use mmW directional transmissions. In some cases, base station <NUM>-c may configure backhaul wireless links <NUM> between other base stations <NUM>. For example, base station <NUM>-c may configure the backhaul wireless link <NUM>-a between base station <NUM>-a and base station <NUM>-d. In some cases, the base station <NUM>-c, which may act as an access node relative to the other base stations <NUM>, and may configure the backhaul wireless links <NUM> by initiating a communication link management procedure that may be used to identify, a suitable pair of transmit and receive beams that can support communication over a backhaul wireless link <NUM>.

Wireless backhauling and fronthauling between base stations <NUM> may be useful in deployments having relatively high densities of base stations, such as deployments that use mmW transmissions, because such techniques enable flexible and lower cost deployments of such relatively small cells. When referring to backhauling and fronthauling, reference is made to communications between base stations, between relays and base stations, or between base stations and a core network, which may be made over backhaul links between a base station and a core network and over fronthaul links within a base station, between base stations, or between a relay and a base station. The terms backhauling and fronthauling refer generally to such communications. Furthermore, mmW transmissions are well suited for extended wireless backhaul/fronthaul networks due to their support of narrow antenna beams, which reduces inter-link interference. Accordingly, due to the limited range of mmW-based access, mmW cells are inherently small in nature which would increase deployment cost if a wireline connection were provided to each base station <NUM>. This, coupled with the ability for mmW transmissions to have relatively narrow pencil beams with low inter-link interference, results in wireless backhauling and fronthauling being an attractive technique for such deployments. Wireless fronthauling may be performed by CUs, DUs, and relays, such as illustrated in <FIG>.

<FIG> illustrate examples of network architectures <NUM> and <NUM> that support radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, network architectures <NUM> and <NUM> may implement aspects of wireless communication system <NUM> or <NUM>.

With respect to <FIG>, a CU/DU split architecture <NUM> is illustrated in which multiple access nodes (e.g., a base station or gNB) may be connected with a core network <NUM>. Each access node may be split into a DU and a CU where a DU <NUM> resides at the network edge and supports a wireless connection to a UE <NUM>-b, and the CU can be centralized and split into a control plane (CU-C) <NUM> and a user plane (CU-U) <NUM>. The interface between DU <NUM> and CU-C <NUM> and CU-U <NUM> may be referred to as a fronthaul interface. In the CU/DU split architecture, the UE <NUM>-b may connect to the DU <NUM> (and to CU-C <NUM> and CU-U <NUM> through the DU <NUM>) and establish RBs such as SRBs and DRBs. Each RB may be divided into a lower portion and an upper portion, as will be discussed in more detail below with respect to <FIG>. The CU/DU architecture sustains a signaling connection between the CU-C <NUM> and DU <NUM> referred to as F1-C. One portion of F1-C may be a fronthaul application protocol, referred to as F1-AP.

In some cases, wireless backhauling/fronthauling between access nodes may be implemented using a layer-<NUM> relay, such as illustrated in <FIG>. In the example of <FIG>, a CU/DU split architecture <NUM> with a relay <NUM> is illustrated in which multiple access nodes (e.g., a base station or gNB) may be connected with core network <NUM>. Each access node may have a CU/DU architecture as described above. In this example, a layer-<NUM> (L2) relay <NUM> may be used to establish wireless backhauling or wireless fronthauling. The L2-relay <NUM> connects to an access node (e.g., a base station or a gNB) in a similar manner as a UE established a wireless connection. To implement such a UE-like connection, the relay <NUM> may have a UE-function (UEF) <NUM> (e.g., a mobile termination function (MTF)) that may be used to establish radio bearers with DU-<NUM><NUM>, CU-C <NUM>, and CU-U <NUM>, and may use these RBs to backhaul traffic between a remote UE <NUM>-c that connects to the relay <NUM>. The UE <NUM>-c may connect to DU-<NUM><NUM> at the relay <NUM>. By combining the L2-relay <NUM> with the CU/DU architecture, wireless relaying is supported where the remote UE <NUM>-c may connect to the relay <NUM> in the same manner as it connects to a base station. In this manner, UEs can transparently connect to either relays or base stations. Hence, relaying can be supported for legacy UEs and no additional features related to proximity services are required on the UE.

The UEF <NUM> may connect to an access node that includes DU-<NUM><NUM>, CU-U <NUM> and CU-C <NUM> using SRBs and DRBs in the same manner as discussed above with respect to <FIG>, and the RBs may have upper and lower portions as will be discussed in further detail below with respect to <FIG>. As the UEF <NUM> provides UE-like functionality, the relay <NUM> may support RRC functionality to connect to the access node that includes DU-<NUM><NUM>, CU-U <NUM> and CU-C <NUM>. RRC functionality may involve exchanging various control messages, which may be referred to as a first set of control messages, associated with RRC control of an access link of UEF <NUM>. More specifically, the UEF <NUM> may use a lower portion of SRBs and DRBs to connect to DU-<NUM><NUM> and an upper portion of these SRBs and DRBs to connect to the respective CU-C <NUM> and CU-U <NUM>.

The relay <NUM> uses its DU, referred to as DU-<NUM><NUM> in <FIG>, to support connections with UE <NUM>-c, other UEs, or other UEFs (residing on other relays), and for that purpose the relay <NUM> supports a fronthaul control connection <NUM> between DU-<NUM><NUM> and CU-C <NUM>, which may be referred to as F1-C in the CU/DU split architecture. The F1-C control connection <NUM> may have an associated second set of control messages for fronthaul control protocol messages. A user plane connection <NUM> may also be supported between DU-<NUM><NUM> and CU-U <NUM>. Thus, relay <NUM> supports two control associations, one for RRC control, and a second for F1-C or fronthaul control. Various aspects of the present disclosure, as will be discussed in more detail below, provide techniques for multiplexing the two different sets of control messages exchanged with a relay such as relay <NUM>.

<FIG> illustrate examples of distributed edge nodes and relay nodes in network architectures <NUM> and <NUM> that support radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, network architectures <NUM> may implement aspects of wireless communication system <NUM> or <NUM>.

As discussed above, RBs such as DRBs and SRBs may be established between a relay and a DU and CU. In the example of <FIG>, a UE <NUM>-d may set up a RB between a DU <NUM> and a CU <NUM>. As mentioned above, each RB may be divided into a lower portion and an upper portion, and in the example of <FIG> UE <NUM>-d configures an upper RB portion <NUM> and a lower RB portion <NUM>. The lower RB portion <NUM> interconnects the UE <NUM>-d and the DU <NUM>, and the upper RB portion <NUM> interconnects the UE <NUM>-d directly with the CU <NUM>. The lower RB portion <NUM> is extended from the DU <NUM> to the CU <NUM> via a tunnel <NUM> which runs across the fronthaul connection <NUM>. In this manner, SRBs are routed from UE <NUM>-d to a CU-C at CU <NUM> while DRBs are routed from UE <NUM>-d to a CU-U at CU <NUM>. The lower RB portion <NUM> may include physical/medium access control (PHY/MAC) and radio link control (RLC) layers, while the upper RB portion <NUM> may include a packet data convergence protocol (PDCP) layer. Alternatively, the lower RB portion <NUM> may include PHY/MAC and only a lower part of RLC layer (e.g. which only performs segmentation), while the upper RB portion <NUM> may include an upper part of RLC (e.g. which performs retransmissions) and a PDCP layer. Other divisions of a RB into upper and lower portions are possible.

In the example of <FIG>, a relay <NUM> may uses its DU, referred to as DU2, to have further UEs or UEFs (e.g., MTFs) (residing on relays) connect to itself, and may also use its UEF for a wireless fronthaul connection to a CU, via another DU such as a DU-<NUM><NUM>. For that purpose, DU-<NUM> at relay <NUM> may support a control connection between DU-<NUM> and CU-C <NUM>, referred to as F1-C <NUM> in the CU/DU split architecture. A CU-C <NUM> at the access node and the relay <NUM> may thus have an RRC connection <NUM> and F1-C connection <NUM>. Various aspects of the present disclosure, as will be discussed in more detail below, provide techniques for multiplexing the two different sets of control messages exchanged with a relay such as relay <NUM>.

<FIG> illustrates an example of a network node configuration <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, network node configuration <NUM> may implement aspects of wireless communication system <NUM> or <NUM>.

In the example of <FIG>, a relay <NUM> may contain a DU-<NUM>/UEF (e.g., an MTF), and may establish connections with another DU, namely DU-<NUM><NUM>, and a CU-C <NUM>. In this example, the UEF on the relay <NUM> may establish an RRC connection <NUM> to the CU-C <NUM> over a first SRB, referred to as SRB-A in <FIG>. The first SRB may have an upper portion <NUM> and a lower portion <NUM> is extended from DU-<NUM><NUM> to the CU-C <NUM> via tunnel-A <NUM> which runs across the fronthaul connection <NUM>. In this example, RRC protocol control messages may be exchanged with CU-C <NUM> via the first SRB. In this example, the CU-C <NUM> configures a second SRB, referred to as SRB-B, for an F1-C connection <NUM>. The second SRB may have an upper portion <NUM> and a lower portion <NUM> is extended from DU-<NUM><NUM> to the CU-C <NUM> via tunnel-B <NUM> which runs across the fronthaul connection <NUM>. In this example, F1-C protocol control messages may be exchanged with CU-C <NUM> via the second SRB.

Each of the first SRB and the second SRB may be specified by a cell radio network temporary identifier (C-RNTI) and a logic channel identifier (LCID). SRB-A and SRB-B may be differentiated by the LCID, for instance. Thus, in this example, a first set of control messages may be carried by the first SRB, and a second set of control messages may be carried by the second SRB, and thus both sets of control messages may be exchanged with the relay <NUM>.

<FIG> illustrates an example of a network node configuration <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, network node configuration <NUM> may implement aspects of wireless communication system <NUM>.

In the example of <FIG>, a relay <NUM> may contain a DU-<NUM>/UEF (e.g., an MTF), and may establish connections with another DU, namely DU-<NUM><NUM>, and a CU-C <NUM>. In this example, the UEF on the relay <NUM> may establish an RRC connection <NUM> to the CU-C <NUM> over a first SRB, referred to as SRB-A in <FIG>. The first SRB may have an upper portion <NUM> and a lower portion <NUM> is extended from DU-<NUM><NUM> to the CU-C <NUM> via tunnel-A <NUM> which runs across the fronthaul connection <NUM>. In this example, RRC protocol control messages may be exchanged with CU-C <NUM> via the first SRB. In this example, DU-<NUM> at the relay <NUM> and CU-C may then exchange F1-C messages <NUM> over RRC by encapsulating F1-C messages into an RRC container. Such a container may contain the F1-C control messages may be flagged appropriately such that the DU and CU can recognize the messages. The F1-C messages <NUM> may refer to an F1 Application Protocol (F1-AP) at DU-<NUM> on relay <NUM> and on CU-C <NUM>. Thus, in this example, a first set of control messages may be carried by the first SRB, and a second set of control messages may be encapsulated within the first set of control messages and also be carried by the first SRB, and thus both sets of control messages may be exchanged with the relay <NUM>.

In the example of <FIG>, a relay <NUM> may contain a DU-<NUM>/UEF (e.g., an MTF), and may establish connections with another DU, namely DU-<NUM><NUM>, and a CU-C <NUM>. In this example, the UEF on the relay <NUM> may establish an RRC connection for exchanging RRC messages <NUM> with the CU-C <NUM> over a first SRB, referred to as SRB-A in <FIG>. The first SRB may have a first upper portion <NUM>, referred to as SRB-A1-up, a second upper portion <NUM> referred to as SRB-A2-up, and a lower portion <NUM> referred to as SRB-A-low, which is extended from DU-<NUM><NUM> to the CU-C <NUM> via tunnel-A1 <NUM> and tunnel-A2 <NUM> which run across the fronthaul connection <NUM>. In this example, RRC protocol control messages may be exchanged with CU-C <NUM> via SRB-A1-up.

In this example, a multiplexing (MUX) layer <NUM> is inserted between lower portion <NUM> and upper portions <NUM> and <NUM> of the SRB-A. This layer multiplexes between RRC messages <NUM> and DU F1-C control messages <NUM>, and may be carried between relay <NUM> and DU-<NUM><NUM>. RRC messages <NUM> and DU F1-C control messages <NUM> share the same lower portion <NUM> of SRB-A. RRC messages <NUM> may be supported by the first SRB upper portion <NUM> (SRB-A1). DU F1-C control messages <NUM> may run natively on the MUX layer <NUM> or they run on the second SRB upper portion <NUM> (SRB-A2). The DU1/CU-C supports independent tunnels, referred to as Tunnel-A1 and Tunnel-A2, on the fronthaul. Thus, in this example, both a first set of control messages and a second set of control messages may be carried by the first SRB-A-low through multiplexing of the DU F1-C control messages <NUM> with the upper portion of SRB-A1-up that carries RRC messages <NUM>, and thus both sets of control messages may be exchanged with the relay <NUM>.

In the example of <FIG>, multiplexing may be used to multiplex F1-C control messages <NUM> with an upper portion of the SRB that carries RRC messages <NUM>, similarly as described in <FIG>, and MUX layer <NUM> stretches from the relay <NUM> to the CU-C <NUM>. Thus, only one tunnel, referred as Tunnel-A, is needed on the fronthaul. Remaining aspects of <FIG> are the same, and a relay <NUM> may contain a DU-<NUM>/UEF (e.g., an MTF), and may establish connections with another DU, namely DU-<NUM><NUM>, and a CU-C <NUM>. In this example, the UEF on the relay <NUM> may establish an RRC connection <NUM> to the CU-C <NUM> over a first SRB, referred to as SRB-A in <FIG>. The first SRB may have a first upper portion <NUM>, referred to as SRB-A1, a second upper portion <NUM> referred to as SRB-A2, and a lower portion <NUM> is extended from DU-<NUM><NUM> to the CU-C <NUM> via tunnel-A1 <NUM> and tunnel A2 <NUM> which run across the fronthaul connection <NUM>. In this example, RRC protocol control messages may be exchanged with CU-C <NUM> via the first SRB.

As mentioned, the MUX layer <NUM> stretches from the relay <NUM> to the CU-C <NUM>, and is inserted between lower portion SRB-A <NUM>, which is extended by Tunnel-A <NUM> between DU-<NUM> and CU-C, and upper portions SRB-A1-up <NUM> and SRB-A2-up <NUM>. This layer multiplexes between RRC messages <NUM> and DU F1-C control messages <NUM>, and may be carried between relay <NUM> and CU-C <NUM>. RRC messages <NUM> and DU F1-C control messages <NUM> share the same lower portion <NUM> of SRB-A. RRC messages <NUM> may be supported by the first SRB upper portion <NUM> (SRB-A1). DU F1-C control messages <NUM> may or may not be supported by the second SRB upper portion <NUM> (SRB-A2). As the MUX layer <NUM> stretches across DU-<NUM><NUM>, a single tunnel, referred to as Tunnel-A <NUM>, may be used on the fronthaul. Thus, in this example, both a first set of control messages and a second set of control messages may be carried by the first SRB through multiplexing of the DU F1-C control messages <NUM> with the upper portion of the SRB that carries RRC messages <NUM>, and thus both sets of control messages may be exchanged with the relay <NUM>.

In the example of <FIG>, F1-C messages <NUM> may be carried on a dedicated DRB between relay <NUM> and CU-C <NUM> and encapsulated in an intra-CU control channel <NUM> between CU-U <NUM> and CU-C <NUM>. Other architecture portions are similar as discussed above with respect to <FIG>, and a relay <NUM> may contain a DU-<NUM>/UEF (e.g., an MTF), and may establish connections with another DU, namely DU-<NUM><NUM>, CU-U <NUM>, and CU-C <NUM>. In this example, the UEF on the relay <NUM> may establish a DRB with CU-U <NUM> that has an upper portion <NUM> and a lower portion <NUM> is extended from DU-<NUM><NUM> to the CU-U <NUM> via tunnel <NUM> which runs across the fronthaul connection <NUM>. As mentioned above, in this example, F1-C messages <NUM> may be carried on a dedicated DRB between relay <NUM> and CU-C <NUM> and encapsulated in an intra-CU control channel <NUM> between CU-U <NUM> and CU-C <NUM>. A transport connection <NUM> may be established between CU-U <NUM> and CU-C <NUM>. RRC protocol control messages may be exchanged with CU-C <NUM> via a first SRB, in a similar manner as discussed above with respect to <FIG> and <FIG>. Thus, in this example, a first set of control messages may be carried by the SRB, and a second set of control messages may be carried by the DRB, and thus both sets of control messages may be exchanged with the relay <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communication system <NUM> or <NUM>. Process flow <NUM> may include a relay <NUM>, a DU-<NUM><NUM>, a CU-C <NUM>, and a core network <NUM>, which may each be examples of the corresponding devices such as described with reference to <FIG>. In this example, multiple SRBs may be established as discussed above in the example of <FIG>.

In this example, at block <NUM>, a UEF (e.g., an MTF) at the relay <NUM> may establish an RRC connection with CU-C <NUM> via DU-<NUM><NUM>. The relay <NUM> may establish an initial SRB, referred to as SRBO <NUM>, and may provide an indicator that informs the CU-C <NUM> that the relay <NUM> has relay functionality.

The UEF at the relay <NUM> may send a non-access stratum (NAS) N2 protocol data unit (PDU) Session Establishment Request <NUM> to the core network <NUM> via the CU-C <NUM>. Between the relay <NUM> and CU-C <NUM>, this NAS message may be encapsulated in RRC.

At block <NUM>, NAS over RRC, the relay <NUM> may perform authentication/authorization with the core network <NUM>. The core network <NUM> may transmit a PDU Session Request message <NUM> to the CU-C <NUM>. Responsive thereto, the CU-C <NUM> may send an F1-AP configuration message <NUM> to DU-<NUM><NUM> to establish the lower portions of SRB-A and SRB-B and the corresponding tunnels, Tunnel-A and Tunnel-B, as described above with respect to <FIG>. The CU-C <NUM> itself establishes the other end points of Tunnel-A and Tunnel-B and the respective upper portion of SRB-A and SRB-B on top.

The CU-C <NUM> may then send an RRC configuration message <NUM> to the relay <NUM> to establish the lower and the upper portion of SRB-A <NUM> and SRB-B <NUM>. The CU-C <NUM> may send a PDU Session Request Ack message <NUM> to the core network <NUM>.

The relay <NUM> may then launch DU-<NUM>, as illustrated in <FIG>, and at block <NUM> may establish F1-C and exchange F1-C messages with the CU-C <NUM> via SRB-B <NUM>, and exchange RRC messages with CU-C via SRB-A <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communication system <NUM> or <NUM>. Process flow <NUM> may include a relay <NUM>, a DU-<NUM><NUM>, a CU-C <NUM>, and a core network <NUM>, which may each be examples of the corresponding devices such as described with reference to <FIG>. In this example, F1-C control messages may be encapsulated in RRC messages, as discussed above in the example of <FIG>.

The UEF at the relay <NUM> may send a NAS N2 PDU Session Establishment Request <NUM> to the core network <NUM> via the CU-C <NUM>. Between the relay <NUM> and CU-C <NUM>, this NAS message may be encapsulated in RRC.

At block <NUM>, NAS over RRC, the relay <NUM> may perform authentication/authorization with the core network <NUM>. The core network <NUM> may transmit a PDU Session Request message <NUM> to the CU-C <NUM>. Responsive thereto, the CU-C <NUM> may send an F1-AP configuration message <NUM> to DU-<NUM><NUM> to establish the lower portion of SRB-A <NUM> and the corresponding tunnel, Tunnel-A. The CU-C <NUM> itself establishes the other end point of Tunnel-A as well as the corresponding upper portion of SRB-A <NUM>.

The CU-C <NUM> may then send an RRC configuration message <NUM> to the relay <NUM> to establish the lower and the upper portion of SRB-A. The CU-C <NUM> may send a PDU Session Request Ack message <NUM> to the core network <NUM>.

The relay <NUM> may then launch DU-<NUM>, as illustrated in <FIG>, and at block <NUM> may establish F1-C and exchange encapsulated F1-C messages with the CU-C <NUM> over RRC messages.

<FIG> illustrates an example of a process flow <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communication system <NUM> or <NUM>. Process flow <NUM> may include a relay <NUM>, a DU-<NUM><NUM>, a CU-C <NUM>, and a core network <NUM>, which may each be examples of the corresponding devices such as described with reference to <FIG>. In this example, multiplexing may be used to multiplex F1-C messages and an upper portion of an SRB as discussed above in the example of <FIG>.

At block <NUM>, NAS over RRC, the relay <NUM> may perform authentication/authorization with the core network <NUM>. The core network <NUM> may transmit a PDU Session Request message <NUM> to the CU-C <NUM>. Responsive thereto, the CU-C <NUM> may send an F1-AP configuration message <NUM> to DU-<NUM><NUM> to establish the lower portion of SRB-A, which is shared between the upper portions, SRB-A1 <NUM> and SRB-A2 <NUM>, and the extending tunnels, Tunnel-A1 and Tunnel-A2. The CU-C <NUM> itself establishes the other end points of Tunnel-A1 and Tunnel-A2 as well as the corresponding upper SRB portions, namely SRB-A1 <NUM> and SRB-A2 <NUM>.

The CU-C <NUM> may then send an RRC configuration message <NUM> to the relay <NUM> to establish the lower portion of SRB-A, which is shared between the upper portions, SRB-A1 <NUM> and SRB-A2 <NUM>. The CU-C <NUM> may send a PDU Session Request Ack message <NUM> to the core network <NUM>.

The relay <NUM> may then launch DU-<NUM>, as illustrated in <FIG>, and at block <NUM> may establish F1-C and exchange F1-C messages with the CU-C <NUM> via SRB-A2 <NUM>. The relay <NUM> may exchange RRC messages with the CU-C <NUM> over SRB-A1 <NUM>. The relay <NUM> and DU-<NUM><NUM> may multiplex SRB-A1 <NUM> and SRB-A2 <NUM> messages onto the lower portion SRB-A via the MUX layer as described in <FIG>.

At block <NUM>, NAS over RRC, the relay <NUM> may perform authentication/authorization with the core network <NUM>. The core network <NUM> may transmit a PDU Session Request message <NUM> to the CU-C <NUM>. Responsive thereto, the CU-C <NUM> may send an F1-AP configuration message <NUM> to DU-<NUM><NUM> to establish the lower portion of SRB-A and an extending tunnel, Tunnel-A, as well as the upper portions, SRB-A1 <NUM> and SRB-A2 <NUM>, which share the lower portion SRB-A and Tunnel-A. The CU-C <NUM> itself establishes the other end point of Tunnel-A as well as the corresponding upper SRB portions, namely SRB-A1 <NUM> and SRB-A2 <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports radio resource control and fronthaul control in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communication system <NUM> or <NUM>. Process flow <NUM> may include a relay <NUM>, a DU-<NUM><NUM>, a CU-C <NUM>, a CU-U <NUM>, and a core network <NUM>, which may each be examples of the corresponding devices such as described with reference to <FIG>. In this example, a DRB may be used for F1-C messages and an SRB may be used for RRC messages as discussed above in the example of <FIG>.

At block <NUM>, NAS over RRC, the relay <NUM> may perform authentication/authorization with the core network <NUM>. The core network <NUM> may transmit a PDU Session Request message <NUM> to the CU-C <NUM>. Responsive thereto, the CU-C <NUM> may send an F1-AP configuration message <NUM> to the DU-<NUM><NUM> to establish the lower portions of SRB-A <NUM>, DRB-A <NUM> and DRB-B <NUM> and the corresponding tunnels, Tunnel-SA , Tunnel-DA and Tunnel-DB. The CU-C <NUM> itself establishes the other end points of Tunnel-SA.

The CU-C <NUM> may then send an RRC configuration message <NUM> to the relay <NUM> to establish the lower and the upper portion of SRB-A <NUM>, DRB-A <NUM> and DRB-B <NUM>.

The CU-C <NUM> may uses an Intra-CU control channel <NUM> to configure on the CU-U <NUM> the tunnel end points, Tunnel-DA and Tunnel-DB and the respective upper portion of DRB-A <NUM> and DRB-B <NUM> on top. The CU-C <NUM> may send a PDU Session Request Ack message <NUM> to the core network <NUM>.

The relay <NUM> may then launch DU-<NUM>, as illustrated in <FIG>, and at block <NUM> may establish F1-C and exchange F1-C messages with the CU-U <NUM> via CU-C <NUM>, where the messages are carried on one of the DRBs between Relay <NUM> and CU-C <NUM> and encapsulated on the Intra-CU control channel between CU-U <NUM> and CU-C <NUM>. The relay <NUM> exchanges RRC messages with CU-C <NUM> via SRB-A <NUM>. The RRC and F1-C messages may be transmitted using the different RBs, as described in <FIG>.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports radio resource control and fronthaul control in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> as described herein. Wireless device <NUM> may include receiver <NUM>, communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Receiver <NUM> may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to radio resource control and fronthaul control, etc.). Information may be passed on to other components of the device. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>. The receiver <NUM> may utilize a single antenna or a set of antennas.

Communications manager <NUM> may be an example of aspects of the communications manager <NUM> described with reference to <FIG>.

Communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure. The communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

Communications manager <NUM> may establish a SRB with a CU for exchanging control messages with the CU, identify a first set of control messages for an access radio link with the CU and a second set of control messages for a fronthaul radio link with the CU, configure a lower portion of the SRB for transmission of at least a portion of the first set of control messages and a portion of a second set of control messages, configure an upper portion of the SRB for transmission of at least a portion of the first set of control messages, multiplex the upper portion of the SRB and the second set of control messages, and transmit the multiplexed upper portion of the SRB and second set of control messages to the CU.

The communications manager <NUM> may also establish a SRB with a CU for exchanging control messages with the CU, identify a first set of control messages for an access radio link with the CU and a second set of control messages for a fronthaul radio link with the CU, transmit the first set of control messages using the SRB, encapsulate one or more of the second set of control messages into the first set of control messages, and transmit the encapsulated first set of control messages using the SRB.

The communications manager <NUM> may also identify a first set of control messages for an access radio link with a CU and a second set of control messages for a fronthaul radio link with the CU, establish a first RB with the CU for exchanging the first set of control messages, establish a second RB with the CU for exchanging the second set of control messages, and transmit the first set of control messages using the first RB and the second set of control messages using the second RB.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports radio resource control and fronthaul control in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a base station <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Communications manager <NUM> may be an example of aspects of the communications manager <NUM> described with reference to <FIG>. Communications manager <NUM> may also include radio bearer establishment manager <NUM>, fronthaul communication manager <NUM>, SRB manager <NUM>, multiplexer <NUM>, and encapsulation component <NUM>.

Radio bearer establishment manager <NUM> may establish a SRB with a CU for exchanging control messages with the CU, and in some cases may establish a second SRB with the CU. In some cases, radio bearer establishment manager <NUM> may establish a first RB with the CU for exchanging the first set of control messages, establish a second RB with the CU for exchanging the second set of control messages, and may also establish a third RB (e.g., SRBO) with the CU.

Fronthaul communication manager <NUM> may identify a first set of control messages for an access radio link with the CU and a second set of control messages for a fronthaul radio link with the CU. In some cases, fronthaul communication manager <NUM> may, receive a configuration for the upper portion of the first SRB and the lower portion of the first SRB over the second SRB. In some cases, fronthaul communication manager <NUM> may transmit the encapsulated first set of control messages using the SRB. In some cases, fronthaul communication manager <NUM> may transmit a multiplexed upper portion of the SRB and second set of control messages to the CU. In some cases, fronthaul communication manager <NUM> may transmit the first set of control messages using the first RB and the second set of control messages using the second RB.

In some cases, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link. In some cases, a DU) supports a UEF (e.g., an MTF) and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, the second set of control messages are fronthaul control protocol messages and the first set of control messages are radio resource control (RRC) protocol messages. In some cases, the first set of control messages configure the lower portion of the SRB. In some cases, the first set of control messages configure the lower portion and the upper portion of the SRB for the fronthaul radio link. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, the second set of control messages are fronthaul control protocol messages and the first set of control messages are RRC protocol messages.

In some cases, the first set of control messages configure a lower portion of the SRB. In some cases, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link. In some cases, a DU supports a UEF and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, a DU supports a UEF and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU.

SRB manager <NUM> may configure a lower portion of the SRB for transmission of at least a portion of the first set of control messages and a portion of a second set of control messages and configure an upper portion of the SRB for transmission of at least a portion of the first set of control messages. In some cases, the configuring the upper portion of the SRB further includes receiving a configuration for a first upper portion of the SRB and a second upper portion of the SRB, the first upper portion for RRC messages and the second upper portion for control messages associated with the access radio link, and where the first upper portion of the SRB and the second upper portion of the SRB are multiplexed with the lower portion of the SRB. In some cases, the first RB includes a first SRB with the CU and the second RB includes a second SRB with the CU.

Multiplexer <NUM> may multiplex the upper portion of the SRB and the second set of control messages. In some cases, the multiplexing further includes setting a multiplexing field to indicate whether a lower portion of the SRB includes an upper portion of the SRB or a second set of control messages. Encapsulation component <NUM> may encapsulate one or more of the second set of control messages into the first set of control messages.

<FIG> shows a block diagram <NUM> of a communications manager <NUM> that supports radio resource control and fronthaul control in accordance with aspects of the present disclosure. The communications manager <NUM> may be an example of aspects of a communications manager <NUM>, a communications manager <NUM>, or a communications manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The communications manager <NUM> may include radio bearer establishment manager <NUM>, fronthaul communication manager <NUM>, SRB manager <NUM>, multiplexer <NUM>, encapsulation component <NUM>, fronthaul control manager <NUM>, and DRB manager <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Radio bearer establishment manager <NUM> may establish a SRB with a CU for exchanging control messages with the CU, and in some cases may establish a second SRB with the CU. In some cases, radio bearer establishment manager <NUM> may establish a RB with the CU for exchanging the first set of control messages, establish a second RB with the CU for exchanging the second set of control messages, and may also establish a third RB (e.g., SRBO) with the CU.

In some cases, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link. In some cases, a DU) supports a UEF (e.g., an MTF) and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, the second set of control messages are fronthaul control protocol messages and the first set of control messages are RRC protocol messages. In some cases, the first set of control messages configure the lower portion of the SRB. In some cases, the first set of control messages configure the lower portion and the upper portion of the SRB for the fronthaul radio link. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, the second set of control messages are fronthaul control protocol messages and the first set of control messages are RRC protocol messages.

In some cases, the first set of control messages configure a lower portion of the SRB. In some cases, the second set of control messages configure the lower portion and an upper portion of the SRB for the fronthaul radio link. In some cases, a DU supports a UEF (e.g., an MTF) and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU. In some cases, the access radio link is established between a DU and the CU, and the first set of control messages are exchanged between the DU and the CU. In some cases, a DU supports a UEF and exchanges the fronthaul radio messages with the CU over the lower portion of a radio bearer established between the UEF and a second DU.

Fronthaul control manager <NUM> may configure the lower portion of the SRB to be terminated at a DU and the upper portion of the SRB may be tunneled through the DU directly to the CU.

DRB manager <NUM> may establish a DRB with the CU for exchanging data packets with the CU. In some cases, the first RB includes a first SRB for exchanging control plane control messages with the CU, and the second RB includes a first DRB for exchanging RRC messages with the CU.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports radio resource control and fronthaul control in accordance with aspects of the present disclosure. Device <NUM> may be an example of or include the components of wireless device <NUM>, wireless device <NUM>, or a base station <NUM> as described above, e.g., with reference to <FIG> and <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including communications manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, network communications manager <NUM>, and inter-station communications manager <NUM>. These components may be in electronic communication via one or more buses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more UEs <NUM>.

Processor <NUM> may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a central processing unit (CPU), a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting radio resource control and fronthaul control).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support radio resource control and fronthaul control. Software <NUM> may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software <NUM> may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

Inter-station communications manager <NUM> may manage communications with other base station <NUM>, and may include a controller or scheduler for controlling communications with UEs <NUM> in cooperation with other base stations <NUM>. In some examples, inter-station communications manager <NUM> may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations <NUM>.

<FIG> shows a flowchart illustrating a method <NUM> for radio resource control and fronthaul control in accordance with aspects of the present disclosure. The operations of method <NUM> may be implemented by a base station <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a communications manager as described with reference to <FIG>. In some examples, a base station <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station <NUM> may perform aspects of the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> may establish a SRB with a CU for exchanging control messages with the CU. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a radio bearer establishment manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may identify a first set of control messages for an access radio link with the CU and a second set of control messages for a fronthaul radio link with the CU. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may configure a lower portion of the SRB for transmission of at least a portion of the first set of control messages and a portion of a second set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SRB manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may configure an upper portion of the SRB for transmission of at least a portion of the first set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SRB manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may multiplex the upper portion of the SRB and the second set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a multiplexer as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit the multiplexed upper portion of the SRB and second set of control messages to the CU. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit the first set of control messages using the SRB. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may encapsulate one or more of the second set of control messages into the first set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a encapsulation component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit the encapsulated first set of control messages using the SRB. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may identify a first set of control messages for an access radio link with a CU and a second set of control messages for a fronthaul radio link with the CU. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may establish a first RB with the CU for exchanging the first set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a radio bearer establishment manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may establish a second RB with the CU for exchanging the second set of control messages. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a radio bearer establishment manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit the first set of control messages using the first RB and the second set of control messages using the second RB. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a fronthaul communication manager as described with reference to <FIG>.

In some examples, aspects from two or more of the methods <NUM>, <NUM>, or <NUM> described with reference to <FIG>, <FIG>, or <FIG> may be combined. It should be noted that the methods <NUM>, <NUM>, or <NUM> are just example implementations, and that the operations of the methods <NUM>, <NUM>, or <NUM> may be rearranged or otherwise modified such that other implementations are possible.

The wireless communication system <NUM> or systems described herein may support synchronous or asynchronous operation.

Also, as used herein, including in the claims, "or" as used in a list of items (for example, a list of items prefaced by a phrase such as "at least one of" or "one or more of") indicates an inclusive list such that, for example, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of: A, B, or C" is intended to cover A, B, C, A-B, A-C, B-C, and A-B-C. , as well as any combination with multiples of the same element (e.g., A-A A-A-A, A-A-B, A-A-C, A-B-B, A-C-C, B-B, B-B-B, B-B-C, C-C, and C-C-C or any other ordering of A, B, and C).

As used herein, the phrase "based on" shall not be construed as a reference to a closed set of conditions.

Claim 1:
A method (<NUM>) for wireless communication of a base station (<NUM>) being a relay node providing an user equipment, UE, like function, UEF, comprising:
establishing (<NUM>) a signaling radio bearer, SRB, by the relay node with a central unit, CU, for exchanging control messages with the CU;
identifying (<NUM>) a first set of control messages for an access radio link between the UEF of the relay node and the CU and a second set of control messages for a fronthaul radio link between the UEF of the relay node and the CU;
configuring (<NUM>) a lower portion of the SRB for transmission of at least a portion of the first set of control messages and a portion of the second set of control messages, wherein the lower portion of the SRB interconnects the UEF of the relay node with the CU via at least one distributed unit, DU, wherein the DU and the CU are part of a base station being split into the DU, which resides at the network edge, and the CU, which resides in the cloud;
configuring (<NUM>) an upper portion of the SRB for transmission of at least a portion of the first set of control messages, wherein the upper portion of the SRB interconnects the UEF of the relay node with the CU;
multiplexing (<NUM>) the upper portion of the SRB and the second set of control messages; and
transmitting (<NUM>) the multiplexed upper portion of the SRB and second set of control messages to the CU.