Small data transmission to the decomposed base station in the inactive state

Abstract

Methods, systems, and devices for wireless communication are described. Generally, a user equipment (UE) may directly send small data to a decomposed base station without performing a random access procedure. A CU-CP may provide a list of routing identifiers and corresponding data radio bearers (DRBs) to a distributed unit (DU), and the DU may transmit a connection release message to the UE. The connection release message may include the list of routing identifiers and the list of DRB identifiers. The connection release message may further include a downlink monitoring timer. The UE may identify data for uplink transmission and the DRB associated with the data. The UE may transmit a packet having the data and the routing identifier to the DU, and the DU may derive downlink address information from the routing identifier and forward the data to the CU-UP of the aggregated base station.

Description

Technical Field

[0001] The following generally relates to wireless communication, and more particularly, to small data transmission to a decomposed base station in an inactive state. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, and so on. These systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi-access systems include fourth-generation (4G) systems (such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems), and fifth-generation (5G) systems that may be referred to as New Radio (NR) systems. These systems may employ various techniques, 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 Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multi-access communication system may include one or more base stations or one or more network access nodes, each of which simultaneously supports communication of multiple communication devices, which may also be referred to as User Equipment (UE). In some examples, the UE may communicate with a decomposed base station.

[0003] Overview

[0004] The described techniques relate to improved methods, systems, devices, and apparatus for supporting small data transmissions to a split base station in an inactive state. Generally, the described techniques provide for a user equipment (UE) to send small or infrequent data transmissions to a split base station while in an inactive state (e.g., a radio resource control (RRC) inactive state). The UE may send small data directly to the split base station without performing a random access procedure. In such examples, the control unit user plane (CU-UP) of the split base station may independently or in communication with the CU-UP of the split base station determine a set of data radio bearers (DRBs) to keep non-suspended for a UE in an inactive state. The CU-CP may provide this information to a distributed unit (DU) (e.g., an anchor DU), and the DU may convey a connection release message (e.g., an RRC release message) to the UE. The connection release message may include a list of routing identifiers and a list of DRB identifiers for each non-suspended DRB determined by the CU-CP. In some examples, the connection release message may also include a downlink monitoring timer. The UE may use the routing identifiers and DRB identifiers to transmit small data in the RRC inactive state. For example, (e.g., in the case where the UE has moved during the RRC inactive state to a different DU associated with a different CU-UP), the UE may identify the data for uplink transmission and the DRB associated with the data. The UE may transmit a small data packet with the data (e.g., as a sub-protocol data unit (PDU) of a media access control (MAC) protocol data unit (PDU)), and may indicate these routing identifiers to the DU (e.g., in a MAC control element (CE) of the same MAC PDU).

[0005] The DU may decode the PDU message and may determine address information based on the routing identifiers. The address information may include a transport network layer (TNL) address, a tunnel endpoint identifier, etc. Based on the address information, the DU may forward the data packet as a packet data convergence protocol (PDCP) PDU to the CU-UP. The CU-UP may process the data. In some examples, the CU-UP may convey an indication of the uplink data to the CU-CP. In some examples, the CU-UP may send the data to the core network for further processing or initiate a downlink data transmission in response to the uplink data. In some examples, the CU-UP may determine whether to initiate a new connection with the UE. In such examples, the CU-UP may convey a downlink data notification to the CU-CP, and the CU-CP may send paging information to the DU for forwarding to the UE (e.g., during a downlink monitoring window). A subsequent connection may be established with an appropriate CU-UP (e.g., an access split base station corresponding to the location of the UE, which may be different from the previous anchor base station).

[0006] Describes a method for wireless communication at a UE. The method may include: receiving, from a first network node, a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; entering the inactive state based on receiving the connection release message; identifying data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and transmitting, in the inactive state, a packet including the identified data and the at least one routing identifier.

[0007] Describes an apparatus for wireless communication at a UE. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus: to receive, from a first network node, a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; to enter the inactive state based on receiving the connection release message; to identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and to transmit, in the inactive state, a packet including the identified data and the at least one routing identifier.

[0008] Describes another device for wireless communication at a UE. The device may include means for: receiving, from a first network node, a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; entering the inactive state based on receiving the connection release message; identifying data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and transmitting, in the inactive state, a packet including the identified data and the at least one routing identifier.

[0009] Describes a non-transitory computer-readable medium storing code for wireless communication at a UE. The code may include instructions executable by a processor to: receive, from a first network node, a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; enter the inactive state based on receiving the connection release message; identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and transmit, in the inactive state, a packet including the identified data and the at least one routing identifier.

[0010] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: generating a protocol data unit that includes a sub-protocol data unit and a control element, the data unit including the identified data, and the control element including the at least one routing identifier, wherein transmitting the packet includes transmitting the generated protocol data unit.

[0011] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, generating a media access control protocol data unit may further include operations, features, apparatuses, or instructions for the following actions: generating a protocol data unit that includes a set of sub-protocol data units, the set of sub-protocol data units including sub-protocol data units, each sub-protocol data unit in the set of sub-protocol data units corresponding to a respective routing identifier in the set of routing identifiers.

[0012] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the protocol data unit includes a media access control protocol data unit, the sub-protocol data unit includes a media access control sub-protocol data unit or a media access control service data unit, and the control element includes a media access control control element.

[0013] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving an indication of a mapping between the set of routing identifiers and a set of data radio bearers, each routing identifier mapping to at least one data radio bearer in the set of data radio bearers; identifying, from the set of data radio bearers, a data radio bearer associated with the data; and determining, based on the received indication of the mapping, the at least one routing identifier in the set of routing identifiers corresponding to the identified data radio bearer.

[0014] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting the packet may include operations, features, apparatuses, or instructions for the following actions: transmitting the packet to a first network node.

[0015] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting the packet may include operations, features, apparatuses, or instructions for the following actions: transmitting the packet to an additional network node different from the first network node; and receiving downlink data from the additional network node based on transmitting the packet.

[0016] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving a downlink monitoring timer in the connection release message.

[0017] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: identifying a downlink monitoring window for an inactive state based on the received downlink monitoring timer; and monitoring downlink transmissions during the downlink monitoring window in the inactive state.

[0018] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving a paging message based on the monitoring; and establishing a wireless connection based on the received paging message.

[0019] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the connection release message includes a radio resource control release message, the wireless connection between the UE and the first network node includes a radio resource control connection, and the inactive state includes a radio resource control inactive state.

[0020] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the first network node includes a distributed unit of a split base station, and the split base station includes one or more distributed units, a central unit control plane, and one or more central unit user planes.

[0021] A method for wireless communication at a first network node is described. The method may include: transmitting to a UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receiving from the UE, at least in part in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers; and transmitting the data to a third network node based on the received at least one routing identifier.

[0022] An apparatus for wireless communication at a first network node is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus: to transmit to a UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; to receive from the UE, at least in part in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers; and to transmit the data to a third network node based on the received at least one routing identifier.

[0023] Another device for wireless communication at a first network node is described. The device may include means for: transmitting to a UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receiving from the UE, at least in part in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers; and transmitting the data to a third network node based on the received at least one routing identifier.

[0024] A non-transitory computer-readable medium storing code for wireless communication at a first network node is described. The code may include instructions executable by a processor to: transmit to a UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receive from the UE, at least in part in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers; and transmit the data to a third network node based on the received at least one routing identifier.

[0025] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, receiving the data packet may include operations, features, apparatuses, or instructions for the following actions: receiving a protocol data unit that includes a sub-protocol data unit and a control element, the data unit including the identified data, and the control element including the at least one routing identifier, wherein transmitting the packet includes transmitting the generated protocol data unit.

[0026] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the protocol data unit includes a set of sub-protocol data units, the set of sub-protocol data units including sub-protocol data units, and each sub-protocol data unit in the set of sub-protocol data units corresponds to a respective routing identifier in a set of routing identifiers.

[0027] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the protocol data unit includes a media access control protocol data unit, the sub-protocol data unit includes a media access control sub-protocol data unit or a media access control service data unit, and the control element includes a media access control control element.

[0028] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: determining address information of a third network node at least in part based on the at least one routing identifier, wherein transmitting the data to the third network node may be based on the determined address information.

[0029] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the address information includes an uplink tunnel identifier, a transport network layer address, or a combination thereof.

[0030] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, generating a packet data convergence protocol (PDCP) protocol data unit (PPDU), wherein transmitting the data may include operations, features, apparatuses, or instructions for the following actions: transmitting the PPDU along with the address information.

[0031] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving paging information from a second network node; and transmitting the paging information to a UE based on the at least one routing identifier.

[0032] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, a first network node includes a distributed unit, where a second network node includes a control unit control plane, and where a third network node includes a control unit user plane.

[0033] A method for wireless communication at a second network node is described. The method may include: transmitting, to a first network node, a connection release message instructing a UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and receiving, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to a third network node from the third network node.

[0034] An apparatus for wireless communication at a second network node is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus: to transmit, to a first network node, a connection release message instructing a UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and to receive, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to a third network node from the third network node.

[0035] Another device for wireless communication at a second network node is described. The device may include means for: transmitting, to a first network node, a connection release message instructing a UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and receiving, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to a third network node from the third network node.

[0036] A non-transitory computer-readable medium storing code for wireless communication at a second network node is described. The code may include instructions executable by a processor to: transmit, to a first network node, a connection release message instructing a UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and receive, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to a third network node from the third network node.

[0037] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: transmitting a bearer modification request message to a third network node; and receiving a bearer modification response message from the third network node in response to the bearer modification request message, wherein transmitting the connection release message may be based on the received bearer modification response message.

[0038] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the bearer modification request message includes an indication of a set of suspended data radio bearers and a set of non-suspended data radio bearers, the set of non-suspended data radio bearers including the at least one data radio bearer; and the bearer modification response message includes an indication of the set of routing identifiers and a set of data radio bearer identifiers associated with the set of routing identifiers.

[0039] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: determining, for a UE, a set of data radio bearers including the at least one data radio bearer for use in an inactive state of the UE; and identifying a routing identifier in the set of routing identifiers associated with the data radio bearer, wherein transmitting the connection release message may be based on identifying the set of routing identifiers.

[0040] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving an indication of downlink data for the UE transmitted from a third network node; and transmitting paging information to a first network node based on receiving the indication of the downlink data.

[0041] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions for the following actions: receiving an indication of uplink data from the UE from a first network node transmitted to a third network node. Brief Description of the Drawings

[0043] Figure 1 An example of a wireless communication system supporting small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is illustrated.

[0044] Figure 2 An example of a wireless communication system supporting small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is illustrated.

[0045] Figure 3 An example of a process flow that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is illustrated.

[0046] Figure 4 An example of a process flow that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is illustrated.

[0047] Figure 5 An example of a process flow that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is illustrated.

[0048] Figure 6 and Figure 7 A block diagram of a device that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0049] Figure 8 A block diagram of a communication manager that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0050] Figure 9 A diagram of a system that includes a device that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0051] Figure 10 and Figure 11 A block diagram of a device that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0052] Figure 12 A block diagram of a communication manager that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0053] Figure 13 A diagram of a system that includes a device that supports small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0054] Figures 14 to 16 A flowchart of a method that illustrates support for small data transmission to a decomposed base station in an inactive state according to aspects of the present disclosure is shown.

[0055] Detailed description

[0056] In some wireless communication systems, a user equipment (UE) in an inactive state (radio resource control (RRC) inactive state) can identify a small amount of data for transmission. Such small data transmissions can be infrequent or unexpected (e.g., traffic from an instant messaging service, push notifications, or traffic from a wearable device). To transmit this uplink data, the UE can perform a random access procedure (e.g., a random access channel (RACH) procedure) and establish a new RRC connection with the network (e.g., enter the RRC connected state). However, performing the random access procedure to enter the RRC connected state infrequently for each small data transmission can result in unnecessary signaling overhead, time delay, and system latency, as well as excessive consumption of computing resources.

[0057] In some examples, the UE can be mobile (e.g., a cellular phone, a wearable device, a laptop computer, etc.), which can complicate small data transmission techniques. For example, the UE can be connected to a first network node of a split base station (e.g., a distributed unit (DU)). A split base station can include a central unit user plane (CU-UP), a central unit control plane (CU-CP), and one or more DUs. The UE can enter the RRC inactive state by receiving an RRC release message from the first network node (e.g., the anchor DU). Later, the UE can be outside the coverage of the first network node and can identify a small amount of data for transmission to the base station. However, the UE may be within the coverage area of a second network node (e.g., a second DU) that is different from the anchor DU. As a result, the UE may not be able to communicate with the network via the different DU (e.g., in the RRC inactive state) and may not be able to transmit the data.

[0058] In some examples, a UE may send small or infrequent data transmissions to a split base station while in an inactive state (e.g., RRC inactive state). For example, the UE may send small data directly to the split base station without performing a random access procedure. In such examples, the CU-UP of the split base station may determine, independently or by communicating with the CU-UP of the split base station, a set of data radio bearers (DRBs) to keep non-suspended for the UE in the inactive state. The CU-CP may provide this information to the DU (e.g., the anchor DU), and the DU may transmit a connection release message (e.g., an RRC release message) to the UE. The connection release message may include a list of routing identifiers and a list of DRB identifiers for each non-suspended DRB determined by the CU-CP. In some examples, the connection release message may also include a downlink monitoring timer. The UE may use the routing identifiers and DRB identifiers to transmit small data in the RRC inactive state. For example, (e.g., in a case where the UE has moved to a different DU associated with a different CU-UP during the RRC inactive state), the UE may identify the data for an uplink transmission and the DRB associated with the data. The UE may transmit a small data packet with the data (e.g., as a sub-protocol data unit (PDU) of a media access control (MAC) protocol data unit (PDU)), and may indicate these routing identifiers to the DU (e.g., in a MAC control element (CE) of the same MAC PDU).

[0059] In some examples, the UE may start monitoring downlink data (e.g., in response to an uplink data transmission) during a window (e.g., a downlink monitoring window) indicated by the downlink monitoring timer. For example, upon transmitting uplink data, the UE may initiate the downlink monitoring timer (e.g., in the next transmission time interval (TTI) after transmitting the uplink data). The UE may monitor downlink transmissions from the DU for the duration of the downlink monitoring window. This may allow the DU to forward paging information, downlink data, or both to the UE when necessary, without waiting for a previously scheduled monitoring occasion (e.g., a paging monitoring occasion).

[0060] In some examples, the DU can decode the PDU message and can determine address information based on the routing identifier. The address information can include a transport network layer (TNL) address, a tunnel endpoint identifier, etc. Based on the address information, the DU can forward the data packet as a packet data convergence protocol (PDCP) PDU to the CU-UP. The CU-UP can process the data. In some examples, the CU-UP can convey an indication of uplink data to the CU-CP. In some examples, the CU-UP can send the data to the core network for further processing or initiate a downlink data transmission in response to the uplink data. In some examples, the CU-UP can determine whether to initiate a new connection with the UE. In such examples, the CU-UP can convey a downlink data notification to the CU-CP, and the CU-CP can send paging information to the DU for forwarding to the UE (e.g., during a downlink monitoring window). A subsequent connection can be established with an appropriate CU-UP (e.g., an access split base station corresponding to the location of the UE, which can be different from the previous anchor base station).

[0061] Certain aspects of the subject matter described in this disclosure can be implemented to achieve one or more advantages. The described techniques can support improvements in system efficiency such that devices can avoid expensive overhead signaling and connection procedures for transmitting small data transfers in an inactive state. It can also allow the UE to save power, conserve computing resources, and avoid increased latency and system wait times, resulting in an improved user experience. Additionally, a mobile UE may be able to transmit uplink data in a disconnected state even if it is physically located far from the anchor base station. Thus, in many cases, data transmission can occur without a base station relocation procedure. As such, the supported techniques can include improved network operation and, in some examples, can enhance device and network efficiency and other benefits.

[0062] Aspects of the present disclosure are initially described in the context of a wireless communication system and process flow. Aspects of the present disclosure are further illustrated and described by and with reference to apparatus diagrams, system diagrams, and flowcharts related to small data transmission to a split base station in an inactive state.

[0063] Figure 1An example of a wireless communication system 100 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is described. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low-latency communication, communication with low-cost and low-complexity devices, or any combination thereof.

[0064] The base stations 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may be devices of different forms or having different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110, and the UEs 115 and the base stations 105 may establish one or more communication links 125 over the coverage area 110. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support signal communication according to one or more radio access technologies.

[0065] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile, or stationary and mobile at different times. The UEs 115 may be devices of different forms or having different capabilities. Some example UEs 115 are illustrated in Figure 1 . The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as Figure 1 shown in

[0066] Each base station 105 may communicate with the core network 130, or with each other, or both. For example, the base stations 105 may interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105), or indirectly (e.g., via the core network 130), or both directly and indirectly over the backhaul links 120 (e.g., via X2, Xn, or other interfaces). In some examples, the backhaul links 120 may be or include one or more wireless links.

[0067] One or more of the base stations 105 described herein may include or may be referred to by those of ordinary skill in the art as a base transceiver station, radio base station, access point, radio transceiver, Node B, evolved Node B (eNB), next-generation Node B, or gigabit Node B (any of which may be referred to as a gNB), home Node B, home evolved Node B, or other suitable terms.

[0068] The UE 115 may include or may be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or some other suitable term, where the "device" may also be referred to as a unit, station, terminal, or client, etc. The UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine type communication (MTC) device, etc., which may be implemented in various objects such as appliances, vehicles, meters, etc.

[0069] The UE 115 described herein may be capable of communicating with various types of devices, such as other UEs 115 that may sometimes act as relays, as well as base stations 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, relay base stations, etc., as Figure 1 shown.

[0070] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term "carrier" may refer to a set of radio frequency spectrum resources that has a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion (e.g., bandwidth part (BWP)) of a radio frequency spectrum band that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating carrier operation, user data, or other signaling. The wireless communication system 100 may support communicating with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured to have multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used in conjunction with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

[0071] In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates the operation of other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and may be positioned according to a channel raster for discovery by UE 115. A carrier may operate in a stand-alone mode in which initial acquisition and connection may be performed by UE 115 via the carrier, or a carrier may operate in a non-stand-alone mode in which the connection is anchored using a different carrier (e.g., different carriers of the same or different radio access technologies).

[0072] The communication link 125 shown in the wireless communication system 100 may include an uplink transmission from UE 115 to the base station 105, or a downlink transmission from the base station 105 to UE 115. A carrier may carry downlink or uplink communication (e.g., in an FDD mode), or may be configured to carry both downlink communication and uplink communication (e.g., in a TDD mode).

[0073] A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or the wireless communication system 100. For example, the carrier bandwidth may be one of several determined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)) of a carrier of a particular radio access technology. Devices of the wireless communication system 100 (e.g., the base station 105, UE 115, or both) may have a hardware configuration that supports communication on a particular carrier bandwidth, or may be configurable to support communication on one of the carrier bandwidths in a carrier bandwidth set. In some examples, the wireless communication system 100 may include a base station 105 or UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate on a portion (e.g., a subband, BWP) or all of the carrier bandwidth.

[0074] The signal waveform transmitted on a carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may include one symbol period (e.g., the duration of one modulated symbol) and one subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the code rate of the modulation scheme, or both). Thus, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate of UE 115 can be. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and using multiple spatial layers can further increase the data rate or data integrity of communication with UE 115.

[0075] One or more parameter sets for a carrier may be supported, where a parameter set may include subcarrier spacing (Δf) and cyclic prefix. A carrier may be divided into one or more BWPs having the same or different parameter sets. In some examples, UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communication for UE 115 may be limited to one or more active BWPs.

[0076] The time intervals of base station 105 or UE 115 may be expressed in multiples of a basic time unit, which may refer to a sampling period T s = 1 / (Δf max ·N f ) seconds, where Δf max may represent the maximum supported subcarrier spacing, and N f may represent the maximum supported discrete Fourier transform (DFT) size. The time intervals of communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0077] Each frame may include a plurality of consecutively numbered sub - frames or time slots, and each sub - frame or time slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into sub - frames, and each sub - frame may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the sub - carrier spacing. Each time slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix added before each symbol period). In some wireless communication systems 100, a time slot may be further divided into multiple mini - time slots each containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f ) sampling periods. The duration of a symbol period may depend on the sub - carrier spacing or the operating frequency band.

[0078] A sub - frame, time slot, mini - time slot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in bursts of shortened TTI (sTTI)).

[0079] Physical channels may be multiplexed on a carrier according to various techniques. The physical control channel and the physical data channel may be multiplexed on a downlink carrier using, for example, one or more of time - division multiplexing (TDM) techniques, frequency - division multiplexing (FDM) techniques, or hybrid TDM - FDM techniques. A control region (e.g., a control resource set (CORESET)) for the physical control channel may be defined by the number of symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESET) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search a control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. The aggregation level for a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCE)) associated with the encoded information for a control information format with a given payload size. The search space set may include a common search space set configured to send control information to multiple UEs 115 and a UE - specific search space set configured to send control information to a specific UE 115.

[0080] Each base station 105 may provide communication coverage via one or more cells (e.g., macro cells, small cells, hotspots, or other types of cells, or any combination thereof). The term "cell" may refer to a logical communication entity for communicating with a base station 105 (e.g., on a carrier), and may be associated with an identifier (e.g., physical cell identifier (PCID), virtual cell identifier (VCID), or others) for distinguishing adjacent cells. In some examples, a cell may also refer to a geographic coverage area 110 or a portion (e.g., a sector) of the geographic coverage area 110 on which the logical communication entity operates. The scope of such cells may vary from a smaller area (e.g., a structure, a subset of a structure) to a larger area depending on various factors (such as the capabilities of the base station 105). For example, a cell may be or include a building, a subset of a building, or an external space between or overlapping with the geographic coverage area 110, and other examples.

[0081] Macro cells generally cover a relatively large geographic area (e.g., with a radius of several kilometers) and may allow unconstrained access by UEs 115 having a service subscription with the network provider supporting the macro cell. Small cells may be associated with lower-power base stations 105 (compared to macro cells), and small cells may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unconstrained access to UEs 115 having a service subscription with the network provider, or may provide constrained access to UEs 115 associated with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a home or office). A base station 105 may support one or more cells and may also support communication on one or more cells using one or more component carriers.

[0082] In some examples, a carrier may support multiple cells and may be configured with different cells according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access for different types of devices.

[0083] In some examples, base station 105 may be movable and thus provide communication coverage for a mobile geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous network where different types of base stations 105 use the same or different radio access technologies to provide coverage for various geographic coverage areas 110.

[0084] The wireless communication system 100 may support synchronous or asynchronous operation. For synchronous operation, base stations 105 may have similar frame timings, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, base stations 105 may have different frame timings, and in some examples, transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

[0085] Some UEs 115 (such as MTC or IoT devices) may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technologies that allow devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC may include communication from devices integrated with sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents the information to a person interacting with the application. Some UEs 115 may be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wilderness survival monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based commercial charging.

[0086] Some UEs 115 may be configured to operate in power-saving operation modes, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power-saving techniques for the UE 115 include entering a power-saving deep sleep mode when not participating in active communication, operating on a limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of the carrier, or outside the carrier.

[0087] The wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. The UE 115 may be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission-critical functions). Ultra-reliable communication may include private communication or group communication and may be supported by one or more mission-critical services (such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData)). Support for mission-critical functions may include prioritization of services, and mission-critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency may be used interchangeably herein.

[0088] In some examples, the UE 115 may also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographical coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographical coverage area 110 of the base station 105 or may not be able to receive transmissions from the base station 105 for other reasons. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system where each UE 115 transmits to every other UE 115 in the group. In some examples, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between the UEs 115 without involving the base station 105.

[0089] In some systems, the D2D communication link 135 can be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, vehicles can communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these communications. Vehicles can signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information related to the V2X system. In some examples, vehicles in a V2X system can communicate with roadside infrastructure (such as roadside units), or with the network, or with both, using vehicle-to-network (V2N) communication via one or more network nodes (e.g., base station 105).

[0090] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC) or a 5G core (5GC), and the EPC or 5GC can include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)), and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity can manage non-access stratum (NAS) functions, such as the mobility, authentication, and bearer management of a UE 115 served by a base station 105 associated with the core network 130. User IP packets can be transmitted through the user plane entity, which can provide IP address allocation and other functions. The user plane entity can be connected to a network operator IP service 150. The operator IP service 150 can include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or a packet-switched streaming service.

[0091] Some network devices (such as base station 105) can include subcomponents, such as an access network entity 140, which can be an example of an access node controller (ANC). Each access network entity 140 can communicate with each UE 115 through one or more other access network transmission entities 145, which can be referred to as radio heads, intelligent radio heads, or transmit / receive points (TRPs). Each access network transmission entity 145 can include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 can be distributed across various network devices (e.g., radio heads and ANCs) or combined into a single network device (e.g., base station 105).

[0092] The wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the range from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) band or the decimeter band because the wavelengths are in the range from approximately 1 decimeter to 1 meter in length. UHF waves can be blocked or redirected by buildings and environmental features, but these waves can sufficiently penetrate various structures for macrocells to provide service to UEs 115 located indoors. Compared to transmissions using smaller frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz, UHF wave transmissions can be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers).

[0093] The wireless communication system 100 can also operate in the super-high frequency (SHF) band using frequencies from 3 GHz to 30 GHz (also known as the centimeter band) or in the extremely high frequency (EHF) band of the spectrum (e.g., from 30 GHz to 300 GHz) (also known as the millimeter band). In some examples, the wireless communication system 100 can support millimeter wave (mmW) communication between the UE 115 and the base station 105, and the EHF antennas of the corresponding devices can be smaller and more closely spaced than UHF antennas. In some examples, this can facilitate the use of antenna arrays within the devices. However, the propagation of EHF transmissions can experience even greater atmospheric attenuation and shorter ranges than SHF or UHF transmissions. The techniques disclosed herein can be employed across transmissions using one or more different frequency bands, and the use of frequency bands designated across these frequency bands can vary by country or regulatory body.

[0094] The wireless communication system 100 can utilize both licensed and unlicensed radio frequency bands. For example, the wireless communication system 100 can employ licensed-assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed radio frequency band, devices such as the base station 105 and the UE 115 can employ carrier sensing for collision detection and avoidance. In some examples, operation in an unlicensed band can be based on a carrier aggregation configuration (e.g., LAA) in coordination with a component carrier operating in a licensed band. Operations in unlicensed spectrum can include downlink transmissions, uplink transmissions, peer-to-peer (P2P) transmissions, or device-to-device (D2D) transmissions, etc.

[0095] The base station 105 or the UE 115 may be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of the base station 105 or the UE 115 may be located within one or more antenna arrays or antenna panels that can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some examples, the antennas or antenna arrays associated with the base station 105 may be located at different geographical locations. The base station 105 may have an antenna array that has a number of rows and columns of antenna ports for beamforming that the base station 105 can use to support communication with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted via the antenna ports.

[0096] The base station 105 or the UE 115 can use MIMO communication to utilize multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. For example, a transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), where multiple spatial layers are transmitted to the same receiving device; and multi-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices.

[0097] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., the base station 105, the UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining the signals communicated via the antenna elements of an antenna array such that some signals propagating in a particular orientation relative to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signals communicated via the antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried via the antenna elements associated with the device. The adjustment associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0098] Base station 105 or UE 115 may use beam sweeping techniques as part of beamforming operations. For example, base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by base station 105 multiple times in different directions. For example, base station 105 may transmit signals according to different beamforming weight sets associated with different transmission directions. Transmissions in different beam directions may be used (e.g., by the transmitting device (such as base station 105) or the receiving device (such as UE 115)) to identify the beam direction used by base station 105 for later transmission or reception.

[0099] Some signals (such as data signals associated with a particular receiving device) may be transmitted by base station 105 in a single beam direction (e.g., the direction associated with the receiving device (such as UE 115)). In some examples, the beam direction associated with transmission in a single beam direction may be determined based on signals transmitted in one or more beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions and may report an indication of the signal received by UE 115 with the highest signal quality or other acceptable signal quality to base station 105.

[0100] In some examples, transmissions performed by a device (e.g., by base station 105 or UE 115) may use multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from base station 105 to UE 115). UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. Base station 105 may transmit reference signals that may or may not be precoded (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)). UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may use similar techniques for transmitting signals multiple times in different directions (e.g., for identifying the beam direction used by UE 115 for subsequent transmission or reception) or for transmitting signals in a single direction (e.g., for transmitting data to a receiving device).

[0101] A receiving device (e.g., UE 115) may attempt multiple receive configurations (e.g., directional listening) when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from a base station 105. For example, the receiving device may attempt multiple receive directions by: receiving via different antenna sub-arrays, processing received signals according to different antenna sub-arrays, receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as "listening" according to different receive configurations or receive directions. In some examples, the receiving device may use a single receive configuration to receive along a single beam direction (e.g., when receiving a data signal). The single receive configuration may be aligned in a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), or other acceptable signal quality based on listening according to multiple beam directions).

[0102] Wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, the communication of the packet data convergence protocol (PDCP) layer of a bearer or packet may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly for communication on logical channels. The media access control (MAC) layer may perform priority handling and multiplex logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions of the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide the establishment, configuration, and maintenance of an RRC connection supporting a radio bearer for user plane data between UE 115 and base station 105 or core network 130. In the physical layer, transport channels may be mapped to physical channels.

[0103] UE 115 and base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. Hybrid Automatic Repeat reQuest (HARQ) feedback is a technique for increasing the likelihood that data is correctly received over communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., Automatic Repeat reQuest (ARQ)). HARQ may improve the throughput of the MAC layer in poor radio conditions (e.g., low signal-to-noise ratio conditions). In some examples, a device may support simultaneous-slot HARQ feedback, where the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0104] UE 115 may send small or infrequent data transmissions to split base station 105 while in an inactive state. UE 115 may send small data directly to the split base station without performing a random access procedure. In such examples, the CU-UP of split base station 105 may determine, independently or by communicating with the CU-UP of the split base station, the set of DRBs to keep pending for UE 115 in the inactive state. The CU-CP may provide this information to the DU (e.g., the anchor DU), and the DU may transmit a connection release message (e.g., an RRC release message) to UE 115. The connection release message may include a list of routing identifiers and a list of DRB identifiers for each pending DRB determined by the CU-CP. In some examples, the connection release message may also include a downlink monitoring timer. UE 115 may use the routing identifier and the DRB identifier to transmit small data in the RRC inactive state. For example, (e.g., in the case where UE 115 has moved to a different DU associated with a different CU-UP during the RRC inactive state), UE 115 may identify the data for uplink transmission and the DRB associated with the data. UE 115 may transmit a small data packet with the data (e.g., as a sub-PDU of a MAC PDU) and may indicate the routing identifier to the DU (e.g., in a MAC CE of the same MAC PDU).

[0105] Figure 2An example of a wireless communication system 200 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is described. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. The wireless communication system 200 may include a base station 105-a, which may communicate with a core network (e.g., via a Next Generation Core (NGC) 225). In some examples, the wireless communication system 200 may be considered a distributed implementation of the base station 105-a. The NGC 225 may be implemented at least partially in a network cloud. The NGC 225 may include an Access and Mobility Management Function (AMF) and a User Plane Function (UPF).

[0106] The base station 105-a may include one or more Control Units (CUs). A CU may be a component of a gNB (such as the base station 105-a) that controls different cell groups that are part of the base station 105-a or different cell groups served by the base station 105-a. For example, Figure 2 the base station 105-a may include a Control Unit Control Plane (CU-CP) 215 and two Control Unit User Planes (CU-UP) 220. In other examples, the base station 105-a may include a different number of CU-CPs 215 and CU-UPs 220. In some examples, the CU-CP 215 and the CU-UP 220 may be examples of control plane functions that operate and control the gNB in the cloud.

[0107] Base station 105-a may also include one or more distributed units (DUs) 210. The DU 210 may be a functional network node of the base station 105-a, which may perform a subset of the functions of the base station 105-a based on a function split option. The CU-CP 215 and CU-UP 220 may control the operation of the DU 210. In some examples, each DU 210 may be located at a different physical location, and each DU 210 may be adjacent to a radio close to the UE. The CU-CP 215 may control the control plane of the DU 210 and the CU-UP 220 may control the user plane of the DU 210. Each DU 210 may support carrier aggregation, so each DU 210 may have multiple carriers. In some examples, the DU 210 may be a CCG, NCCG, etc. One or more signaling radio bearers (SRBs) may be split among the DUs 210 (e.g., the DUs of the RLC entity storing the master SRB). The SRB may or may not be split on each DU 210. The CU-CP 215 and CU-UP 220 may manage a wide area of DUs 210, but the SRB may be configured to be split only for the DU with which the UE is most likely to communicate. In some examples, the SRB may be used to carry RRC information or other control information between the UE and the network, and the DRB may be used to carry user plane traffic.

[0108] The UE 115-a may communicate with the base station 105-a via the DU 210. This may mean that there are multiple RLC entities running on the DU 210. The UE 115-a may learn of this configuration from the base station 105-a, which notifies the UE which DUs 210 are associated with the SRB or DRB.

[0109] In some examples, the UE 115-a may identify data for transmission when operating in RRC Inactive mode or RRC Idle mode. The UE 115-a may receive an RRC Release message from the DU 210 and may enter the RRC Inactive mode based thereon. However, when identifying data for uplink transmission, the UE 115-a may perform a random access procedure. For example, the UE 115-a may perform a two-step RACH procedure, a four-step RACH procedure, etc. In some examples, the UE 115 (e.g., UE 115-a) may incorporate a small amount of data into the transmission as part of the random access procedure (e.g., the MSGA of the two-step random access procedure, or Message 3 of the four-step random access procedure). In some examples, the UE 115-a may use a flexible payload size to transmit a random access message including data. The size of such a payload may be configured by the network. In some examples, for a random access-based transmission procedure, the UE 115-a may perform a context acquisition or data forwarding procedure in the Inactive state (e.g., with or without anchor base station repositioning). In some examples, the UE 115-a may transmit uplink data on a preconfigured Physical Uplink Shared Channel (PUSCH) resource. For example, when timing advance is valid, the UE 115-a may divert or reuse a configured grant to transmit uplink data.

[0110] When operating in an Inactive state (e.g., Radio Resource Control (RRC) Inactive state), the UE 115-a may identify a small amount of data for transmission. Such small data transmissions may be infrequent or unexpected (e.g., traffic from an instant messaging service, push notifications, or traffic from a wearable device). Performing a random access procedure and entering an Active state to transmit a small amount of data may result in unnecessary signaling overhead, timing delays, and system latency, as well as excessive consumption of computing resources.

[0111] Additionally, the UE 115-a may be mobile (e.g., a cellular phone, a wearable device, a laptop computer, etc.), which may complicate small data transmission techniques. For example, the UE 115-a may be connected to a first network node (e.g., DU 210) of the split base station 105-a. The UE 115-a may enter the RRC Inactive state by receiving an RRC Release message from the first DU 210. Later, the UE 115-a may be outside the coverage of the DU 210 and may identify a small amount of data for transmission to the base station 105-a. However, the UE 115-a may be within the coverage area of a second network node (e.g., a second DU 210) different from the anchor DU 210. As a result, the UE 115-a may not be able to communicate with the network (e.g., in the RRC Inactive state) via the different DU 210 and may not be able to transmit the data.

[0112] Conversely, UE 115-a may send small data transmissions to DU 210 as described herein. For example, UE 115-a may receive additional information (e.g., one or more routing identifiers) included in an RRC release message. UE 115-a may transmit a PDU including such data and routing identifiers (e.g., to another DU 210) such that DU 210 may forward the data to CU-UP, as described with respect to Figures 3 - 5 more specifically described.

[0113] Figure 3 An example of a process flow 300 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is illustrated. In some examples, process flow 300 may implement aspects of wireless communication systems 100 and 200. Process flow 300 may include a decomposed base station 105-b (which includes DU 210-a, CU-CP 215-a, CU-UP 220-a) and UE 115-b, which may be examples of corresponding devices as referenced Figure 1 and Figure 2 described.

[0114] In some aspects, process flow 300 illustrates an example in which UE 115-b may perform an uplink data transmission to decomposed base station 105-a while in an inactive state. In such examples, UE 115-b may successfully send a small amount of uplink data to base station 105-b without performing associated RRC procedures (e.g., without performing a random access procedure, entering the RRC active state, etc.). Thus, UE 115-b may be able to transmit data to base station 105-b without having to perform a CU relocation procedure (e.g., due to relocation of UE 115-b to connect to a different CU at a different decomposed base station 105-b).

[0115] In some examples, prior to the uplink data transmission, CU-CP 215-a may determine a set of routing identifiers (e.g., one routing identifier, or multiple routing identifiers) either through communication with CU-UP 220-a or independently (e.g., as described with reference to Figure 4 more specifically described). Each routing identifier may correspond to at least one DRB (e.g., a single routing identifier corresponds to a single DRB, or a set of routing identifiers corresponds to the respective DRBs in a set of DRBs). That is, CU-CP 215 may identify the set of DRBs to be suspended upon connection release (e.g., termination of the RRC connection), and may also determine a subset of DRBs to be excluded from that set of DRBs. The subset of DRBs may be maintained (e.g., not suspended) for communicating a small amount of data in the RRC inactive state, as described herein.

[0116] At 305, the CU-CP 215-a may transmit and the UE 115-b may receive a connection release message. The connection release message may be an RRC release message. The connection release message may instruct the UE 115-a to release the radio connection between the UE 115-b and the split base station 105-a. The UE 115-b may enter an inactive state based on having received the connection release message. The connection release message may include a set containing one or more routing identifiers, and a set containing one or more DRBs (e.g., DRBs that have been excluded from suspension). In some examples, the connection release message may further include a downlink monitoring timer.

[0117] At 310, the UE 115-b may transmit and the DU 315 may receive a data packet. The data packet may be a protocol data unit (PDU). In some examples, the UE 115-b may be located in the same place or near the same place where it received the connection release message at 305. In such examples, the UE 115-b may transmit the PDU to the same DU 210-a at 310. In some examples, the UE 115-b may have changed its location since the time it received the connection release message at 305 (e.g., may have been carried by its user to another location). In such examples, the UE 115-b may transmit the PDU to a different DU 210-a at 310. Such a different DU 210-a may use the information in the PDU to forward the uplink data, even without a previous connection context of the UE 115-b (e.g., based on a previous RRC connection), as described in more detail in reference Figure 5 The PDU may include a sub-PDU for carrying the uplink data, and a control element having at least one routing identifier. In some examples, multiple DRBs may be supported (e.g., indicated in the connection release message). In such examples, and if the uplink data values multiple sub-PDUs, the PDU may include a set of sub-PDUs, each corresponding to a respective routing identifier. The PDU may be a media access control (MAC) PDU, the PDU may be a MAC sub-PDU or a MAC service data unit, and the CE may be a MAC CE. In the case where the PDU has been transmitted at 310, the UE 115-b may initiate a downlink monitoring window within the duration of the downlink monitoring timer, as described in more detail in reference Figure 4 The PDU may include a sub-PDU for carrying the uplink data, and a control element having at least one routing identifier. In some examples, multiple DRBs may be supported (e.g., indicated in the connection release message). In such examples, and if the uplink data values multiple sub-PDUs, the PDU may include a set of sub-PDUs, each corresponding to a respective routing identifier. The PDU may be a media access control (MAC) PDU, the PDU may be a MAC sub-PDU or a MAC service data unit, and the CE may be a MAC CE. In the case where the PDU has been transmitted at 310, the UE 115-b may initiate a downlink monitoring window within the duration of the downlink monitoring timer, as described in more detail in reference

[0118] At 315, in the case where the PDU has been received at 310, DU 210-a can process the PDU (e.g., can perform MAC processing and RLC processing, and can decode the PDU). In the case where the PDU has been decoded, DU 310-a can determine the address information. For example, DU 210-a can derive the address information based on the routing identifier included in the PDU for forwarding the received data to CU-UP 220-a at 320. The address information can include an uplink tunnel identifier (e.g., tunnel endpoint identifier (TEID)), a transport network layer (TNL) address, etc. DU 210-a can generate a General Packet Radio Service (GPRS) Tunnel Protocol, User Plane (GTP-U) message, which can include the data identified in the PDCP PDU. DU 210-a can also include the derived address information in one or more fields of the GTP-U message.

[0119] At 320, DU 210-a can route the data packet from DU 210-a to CU-UP 220-a based on a preconfigured routing identifier. That is, DU 210-a can transmit and CU-UP 220-a can receive the GTP-U message.

[0120] At 325, CU-UP 220-a can process the GTP-U message received from DU 210-a and can forward the uplink data to the network using the address information. In some examples, CU-UP 220-a can transmit the data to the core network and receive downlink data from the core network, as described in more detail in reference Figure 4 described in more detail.

[0121] Therefore, in the case where the routing identifier has been received in the connection release message and such information is provided in the PDU transmitted at 310, UE 115-b can be able to transmit uplink data in the RRC inactive state. In addition, even if UE 115-b changes its location (e.g., the user is walking, driving, or moving in some other way) such that it transmits the PDU at 310 to a different DU 210 than the DU 210-a from which it received the connection release message at 305, the new DU210-a will have these routing identifiers to determine the appropriate address information at 315. UE 115-b can also be able to receive downlink information in the RRC inactive mode without waiting for a predefined or preconfigured monitoring occasion, as described in more detail in reference Figure 4 described in more detail.

[0122] Figure 4An example of process flow 400 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is illustrated. In some examples, process flow 400 may implement aspects of wireless communication system 100.

[0123] CU-CP 215-b may be prepared to release the RRC connection with UE 115-b. However, CU-CP 215-b may derive one or more routing identifiers corresponding to one or more DRBs that are not to be suspended upon release of the RRC connection. In some examples, CU-CP 215-b may derive these routing identifiers independently. For example, CU-CP may identify local-based GTP-U tunnel address information for each DRB and may derive the routing identifier for each DRB accordingly. In some examples, CU-CP 215-b may communicate with CU-UP 220-b to derive these routing identifiers. For example, at 405, CU-CP 215-b may transmit a bearer modification request message. The bearer modification request message may indicate a request to suspend communication with UE115-c. However, the bearer modification request message may also indicate the exclusion of one or more DRBs from the request to suspend communication. That is, the bearer modification request message may request that some DRBs remain unsuspended for communication from UE 115-c in the RRC inactive state. In such examples, at 410, CU-UP220-b may transmit a bearer modification response message to CU-CP 215-b. The bearer modification response message may include a list of DRB identifiers (e.g., of the unsuspended DRBs) and a list of routing identifiers corresponding to these DRB identifiers.

[0124] In the case of deriving a list of routing identifiers (e.g., one or more routing identifiers), CU-CP 215-b may initiate an RRC connection release with UE 115-c at 415. CU-CP 215-b may provide a connection release message (e.g., an RRC connection release message) to DU 210-b, and DU 210-d may forward the connection release message to UE 115-c. The connection release message may include the list of routing identifiers and the corresponding DRB identifiers. In some examples, the connection release message may also include an indication of a downlink monitoring timer.

[0125] UE 115-c may receive the connection release message at 415 and may release its connection with base station 105-c. UE 115-c may enter the RRC inactive state (e.g., or RRC idle state, etc.) at 415. After entering the RRC inactive state, UE 115-c may identify data for transmission to base station 105-c. This data may be small, and such small data transmissions may be infrequent or unpredictable.

[0126] At 420, UE 115-c may generate a PDU for transmitting the data to base station 105-c. The PDU may include one or more sub-PDUs for transmitting the data. UE 115-c may also include one or more routing identifiers (e.g., one routing identifier for each sub-PDU of the PDU) in the MAC CE of the PDU. DU 210-b may forward the received uplink data to CU-UP 220-b using the routing identifier (preconfigured by CU-CP 215-b in the connection release message at 415). In some examples (e.g., in the case where UE 115-c has not moved out of the coverage area of DU 210 from which it received the connection release message at 415), UE 115-c may transmit the PDU at 420 to the same DU 210 from which it received the connection release message. In some examples (e.g., in the case where UE 115-c has moved out of the coverage area of DU 210 from which it received the connection release message at 415), UE 115-c may transmit the PDU at 420 to a different DU 210-b than the DU 210 from which it received the connection release message. In some examples, UE115-c may determine the DRB associated with the routing identifier based on the mapping provided during the previously released RRC connection.

[0127] In one example, when transmitting the PDU at 420, UE 115-c may initiate a downlink monitoring window 425. For example, during the TTI after transmitting the PDU (e.g., the next time slot after 420), UE 115-c may initiate the downlink monitoring timer received in the connection release message. The timer may run for the duration of the downlink monitoring window 425. When the timer is running (e.g., during the downlink monitoring window 425), UE 115-c may monitor downlink signaling (e.g., downlink data, paging information, etc.) from DU 210-b. When the downlink monitoring timer expires (e.g., at the end of the downlink monitoring window 425), UE 115-c may suppress monitoring except for preconfigured monitoring windows (e.g., paging monitoring occasions, etc.).

[0128] At 430, in the case where the PDU has been received at 420, the DU 210-b can determine the address information for forwarding the data to the CU-UP 220-b. If the DU 210-b is the same DU that forwarded the connection release message at 415, the DU 210-b may already have some or all of the routing identifiers and may not need the routing identifier included in the PDU. However, if the DU 210-b is a different DU 210 from the DU 210 that forwarded the connection release message to the UE 115-c at 415, the DU 210-b can rely on the routing identifier received in the PDU to determine where to forward the data at 435. The DU 210-b can derive the GTP-U address information for forwarding the data based on the routing identifier. The GTO-U address information can include TEID, TNL address, etc. In some examples, the mapping between the GTP-U address information and the routing identifier can be configured in a DNS server. Since the DU 210-b is able to derive the address information based on the routing identifier, anchor base station repositioning may not be required, even in the case where the access DU 210-b (e.g., the DU 210 with the coverage area where the UE 115 is located) does not belong to the anchor base station 105-c (e.g., the base station 105 to which the UE 115-c was previously connected), as described in more detail with reference to Figure 5 Even if a direct Internet Protocol (IP) connection is not available for the CU-UP 220-b that is not part of the anchor base station 105-c, the data can be routed by the CU-UP of the access DU 210 to the anchor CU-UP 220. In some examples, the RLC processing, MAC processing, or both of the PDU can be at least partially based on the default processing configuration for uplink transmission, downlink transmission, or both.

[0129] At 435, the UE 115-c can generate and transmit a GTP-U message including a PDCP PDU to the CU-UP 220-b, where the PDCP PDU carries the data received in the PDU at 420. The GTP-U message can also include the address information. For example, the GTP-U message can include fields for the downlink TEID, downlink TNL address, etc. This information can be used to provide downlink information to the UE 115-b. For example, the address information can indicate the DU 210-b that received the PDU at 420. Thus, the downlink information from the network can be provided back to the DU 210-b based on the address information for forwarding to the UE 115-c.

[0130] At 440, CU-UP 220-b can process the PDCP PDU received at 435. At 445, in some examples, CU-UP 220-b can transmit an uplink data notification message to CU-CP 215-b. This uplink data notification message can indicate to CU-CP 215-b that DU 210-b has forwarded the uplink data to CU-UP 220-b at 435. This can provide relevant information to CU-CP 215-b, which can be used to determine whether to establish an RRC connection with UE 115-c based on this uplink data transmission or any subsequent downlink data transmission. CU-UP 220-b can transmit this uplink data notification before or after receiving the downlink data at 450. In some examples, processing the PDCP PDU can be based on the UE context, the bearer context at CU-UP 220-b, or both. In some examples, security protection can be based on the anchor CU-CP and anchor CU-UP security.

[0131] At 450, CU-UP 220-b can transmit the uplink data received at 435 to the network. In some examples, in response to the uplink data, CU-UP 220-b can receive downlink data at 455. This downlink data can be in response to the uplink data transmitted at 445. In some examples, this downlink data can be for UE115-c.

[0132] At 460, CU-CP can transmit a downlink data notification to CU-CP 215-b. This downlink data notification can indicate pending downlink data, the amount of downlink data to be transmitted to UE 115-c, etc.

[0133] CU-CP 215-b can determine whether to establish another RRC connection with UE 115-c. For example, CU-CP 215-b can determine whether to page UE 115-c to bring UE 115-c back to RRC connected or RRC active state based on data notifications received from CU-UP 220-b (e.g., uplink data notification message at 445, downlink data notification message at 460, or both). In some examples, CU-CP 215-b can also receive one or more downlink non-access stratum (NAS) PDUs, and it can at least partially rely on the one or more NAS PDUs to determine whether to establish an RRC connection with UE 115-c. In some examples, the control network can indicate to base station 105-c whether to initiate an RRC procedure (e.g., in a downlink data notification or a different notification). CU-CP 215-b can determine whether to page UE 115-c based on any of the above signaling and one or more current procedures (e.g., whether handover procedures, relocation procedures, security updates, etc. are pending or required for UE 115-c). Based on one or more inputs from the above, CU-CP 215-b can determine whether to transmit paging information for UE 115-c to DU 210-b.

[0134] If CU-CP 215-b determines to page UE 115-c, then CU-CP 215-b can transmit paging information for UE 115-c to DU 210-b at 465. At 470, DU 210-b can forward the paging information to UE 115-c. In some examples, CU-CP 215-b can transmit the paging information to DU 210-b based on the address information. For example, DU 210-b can include downlink address information in the GTP-U message transmitted at 435. CU-UP 220-b can include some or all of the address information in the uplink data notification message at 445, the downlink data notification at 460, or both. Based on the address information, CU-CP 215-b can identify DU 210-b and can forward the paging information to DU 210-b based on it at 465.

[0135] UE 115-c may receive the paging information at 470. In some examples, UE 115-c may monitor downlink signaling, such as paging information, based on downlink monitoring window 425. That is, in the case where the downlink monitoring timer is initiated after the PDU has been transmitted at 420, UE 115-c may continuously monitor downlink signaling from DU 210-b during the duration of downlink monitoring window 425. In some examples, CU-CP 215-b may have configured the downlink monitoring timer to have the duration of downlink monitoring window 425. If DU 210-b receives the paging information (or downlink data at 475) before the expiration of downlink monitoring window 425, then DU 210-b may immediately forward the paging information to UE 115-c without waiting for a paging monitoring occasion. Thus, UE 115-c may receive the paging information quickly and be able to enter the RRC active or RRC connected state (e.g., for receiving downlink data). In some examples, establishing a new RRC connection with base station 105-b may include an anchor base station repositioning procedure. However, by waiting until after the small data is transmitted, UE 115-c may avoid unnecessary power consumption for one or more small uplink data transmissions that may not result in an anchor base station repositioning procedure.

[0136] At 475, CU-UP 220-b may provide downlink information for UE 115-c to DU 210-b. In some examples, DU 210-b may forward the downlink data to UE 115-c at 450. In some examples, before forwarding the downlink data to UE 115-c, UE 115-c and base station 105-b may perform an RRC connection procedure based on the paging information received at 470. In some examples, depending on the amount of data for downlink transmission, DU 210-b may transmit the downlink data at 450 within downlink monitoring window 425.

[0137] Figure 5 An example of process flow 500 is illustrated that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure. In some examples, process flow 500 may implement aspects of wireless communication systems 100 and 200. Process flow 500 may include a decomposed base station 105-e that includes DU 210-c, CU-CP 215-c, and CU-UP 220-c; and a decomposed base station 105-d that includes DU 210-d, CU-CP 215-d, and CU-UP 220-d, which may be examples of the corresponding devices described with reference to Figures 1 - 4 those described.

[0138] UE 115-d can communicate with base station 105-e (e.g., can operate in RRC connected mode). The split base station 105-e can be referred to as the anchor base station 105-e, and each network node (e.g., DU 210-c, CU-CP 215-c, CU-UP 220-c) can be referred to as an anchor network node. The anchor base station 105-e can access connection context information for UE 115-d during the connection and after the connection is released (e.g., when UE 115-d enters RRC inactive mode).

[0139] At 505, CU-CP 215-c can transmit and UE 115-d can receive a connection release message. The connection release message can be an RRC release message. The connection release message can instruct UE 115-d to release the radio connection between UE 115-d and the anchor base station 105-e. UE 115-d can enter an inactive state based on having received the connection release message. The connection release message can include a set containing one or more routing identifiers, and a set containing one or more DRBs (e.g., DRBs that are not suspended despite the RRC inactive state). In some examples, the connection release message can also include a downlink monitoring timer.

[0140] After receiving the connection release message at 505, UE 115-d can move from a first location to a second location. At the first location, UE 115-d can be within the coverage area of the anchor DU 210-c. However, the user can carry UE 115-d to the second location (e.g., the user may be walking, driving, or otherwise traveling). The second location can be outside the coverage area of the anchor DU 210-c. However, the second location can be within the coverage area of another DU 210-d. DU 210-d can be part of another split base station 105-d. The split base station 105-d can be referred to as the access base station 105-d, and each network node of the access base station 105-d can be referred to as an access network node. Although the access DU 210-d may not be part of the anchor base station 105-e, UE 115-d can still be able to transmit uplink data in the RRC inactive state using the techniques described herein.

[0141] At 510, the UE 115-d may transmit and the access DU 210-d may receive a data packet. In other words, the UE 115-d may transmit the data packet to a different DU 210-d from which it received the connection release message at 505. Sub-PDUs of the PDU may include uplink data, and the CE of the PDU may indicate a routing identifier received from the DU 210-c. Thus, although the access DU 210-d may not have previously communicated with the UE 115-c and although the access base station 105-d may not have context information for the UE 115-d (e.g., based on a previous RRC connection), the DU 210-d may identify a routing identifier for the uplink data from the PDU transmitted at 510 and may forward the data on the access CU-UP 220-d. In some examples, multiple DRBs may be supported (e.g., indicated in the connection release message). In such examples, the PDU may include a set of sub-PDUs, each corresponding to a respective routing identifier. The PDU may be a Media Access Control (MAC) PDU, the PDU may be a MAC sub-PDU or a MAC service data unit, and the CE may be a MAC CE. In the case where the PDU has been transmitted at 510, the UE 115-d may initiate a downlink monitoring window within the duration of a downlink monitoring timer, as described in reference to Figure 4 in more detail.

[0142] At 515, the access DU 210-d may derive address information from these routing identifiers, as described in reference to Figure 4 in more detail. In some examples, the access DU 210-d may determine a mapping between these routing identifiers and these DRBs (e.g., based on previous mapping information, or information indicated by a DNS server). The DU 210-d may forward the data to the CU-UP 220 (e.g., the access CU-UP 220-d) based on these routing identifiers. Additionally, the DU 210-d may derive downlink address information (e.g., TEID and TSN addresses for downlink information) from these routing identifiers.

[0143] At 520, the DU 210-d may transmit a PDCP PDU carrying the uplink data and the address information to the access CU-UP 220-d. In some examples, the CU-UP 220-d may forward the uplink data to the core network.

[0144] In some examples, at 525, CU-UP 220-d may forward the PDCP PDU to anchor base station 105-e. CU-UP 220-d may transmit a GTP-U message including the PDCP PDU and the address information to anchor CU-UP 220-c. At 530, CU-UP 220-c may process the uplink data. If anchor base station 105-e determines to provide paging information to UE 115-d to trigger UE 115-d to enter the RRC active state, anchor base station 105-e may initiate paging of UE 115-d. In some examples, anchor base station 105-e may initiate an anchor relocating procedure, and access base station 105-d may become the new anchor base station for establishing an RRC connection with UE 115-d.

[0145] Figure 6 FIG. 600 is a block diagram of a device 605 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure. Device 605 may be an example of aspects of UE 115 as described herein. Device 605 may include a receiver 610, a communication manager 615, and a transmitter 620. Device 605 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

[0146] Receiver 610 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 small data transmission to a decomposed base station in an inactive state, etc.). The information may be passed to other components of device 605. Receiver 610 may be an example of aspects of transceiver 920 described with reference to Figure 9 Receiver 610 may utilize a single antenna or an antenna array.

[0147] Communication manager 615 may receive a connection release message from a first network node instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; enter the inactive state based on receiving the connection release message; identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and transmit a packet including the identified data and the at least one routing identifier in the inactive state. Communication manager 615 may be an example of aspects of communication manager 910 described herein.

[0148] The communication manager 615 or its sub-components may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 615 or its sub-components may be performed by a general-purpose processor, a DSP, an application specific integrated circuit (ASIC), an 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 this disclosure.

[0149] The communication manager 615 or its sub-components may be physically located at various positions, including being distributed such that portions of the functions are implemented by one or more physical components at different physical locations. In some examples, in accordance with various aspects of the present disclosure, the communication manager 615 or its sub-components may be separate and distinct components. In some examples, in accordance with various aspects of the present disclosure, the communication manager 615 or its sub-components may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in this disclosure, or combinations thereof.

[0150] The transmitter 620 may transmit signals generated by other components of the device 605. In some examples, the transmitter 620 may be co-located with the receiver 610 in a transceiver module. For example, the transmitter 620 may be an example of aspects of the transceiver 920 described with reference to Figure 9 The transmitter 620 may utilize a single antenna or an antenna array.

[0151] In some examples, the communication manager 615 may be implemented as an integrated circuit or chipset for a mobile device modem, and the receiver 610 and transmitter 620 may be implemented as analog components (e.g., amplifiers, filters, antennas) coupled to the mobile device modem to enable wireless transmission and reception on one or more frequency bands.

[0152] The communication manager 615 as described herein may be implemented to achieve one or more potential advantages. One implementation may allow the device to improve system efficiency such that the device can avoid expensive overhead signaling and connection procedures for transmitting small data transfers in an inactive state. It may also allow the UE to save power, conserve computing resources, and avoid increased latency and system wait times, resulting in an improved user experience. Additionally, a mobile UE may be able to transmit uplink data in a disconnected state, even if it is physically located far from an anchor base station. Thus, in many cases, data transmission may occur without a base station relocation procedure. As such, the supported techniques may include improved network operation and, in some examples, may enhance device and network efficiency and other benefits.

[0153] Based on techniques for efficiently communicating the maximum number of layers for a device as described herein, a processor of UE 115 (e.g., controlling receiver 610, transmitter 620, or transceiver 920 as described with reference to Figure 9 ) can improve system efficiency and reduce unnecessary processing at the device.

[0154] Figure 7 FIG. 700 is a block diagram of a device 705 supporting small data transfer to a decomposed base station in an inactive state in accordance with aspects of the present disclosure. Device 705 can be an example of aspects of device 605 or UE 115 as described herein. Device 705 can include a receiver 710, a communication manager 715, and a transmitter 735. Device 705 can also include a processor. Each of these components can be in communication with each other (e.g., via one or more buses).

[0155] The receiver 710 can 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 small data transfer to a decomposed base station in an inactive state, etc.). The information can be passed to other components of device 705. The receiver 710 can be an example of aspects of the transceiver 920 as described with reference to Figure 9 . The receiver 710 can utilize a single antenna or an antenna array.

[0156] The communication manager 715 can be an example of aspects of the communication manager 615 as described herein. The communication manager 715 can include a connection release manager 720, a connection status manager 725, and a data manager 730. The communication manager 715 can be an example of aspects of the communication manager 910 as described herein.

[0157] The connection release manager 720 can receive a connection release message from a first network node instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer.

[0158] The connection status manager 725 can enter the inactive state based on receiving the connection release message.

[0159] The data manager 730 can identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data, and transmit a packet including the identified data and the at least one routing identifier in the inactive state.

[0160] Transmitter 735 can transmit signals generated by other components of device 705. In some examples, transmitter 735 can be co-located with receiver 710 in a transceiver module. For example, transmitter 735 can be an example of aspects of transceiver 920 described with reference to Figure 9 Transmitter 735 can utilize a single antenna or an antenna array.

[0161] Figure 8 Block diagram 800 of communication manager 805 supporting small data transmission to a split base station in an inactive state in accordance with aspects of the present disclosure is shown. Communication manager 805 can be an example of aspects of communication manager 615, communication manager 715, or communication manager 910 described herein. Communication manager 805 can include a connection release manager 810, a connection status manager 815, a data manager 820, a PDU generation manager 825, a routing identifier manager 830, a downlink monitoring manager 835, and a paging manager 840. Each of these modules can communicate directly or indirectly with each other (e.g., via one or more buses).

[0162] Connection release manager 810 can receive a connection release message from a first network node instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer. In some cases, the connection release message includes a radio resource control release message. In some cases, the wireless connection between the UE and the first network node includes a radio resource control connection. In some cases, the inactive state includes a radio resource control inactive state.

[0163] Connection status manager 815 can enter the inactive state based on receiving the connection release message. In some cases, the first network node includes a distributed unit of a split base station, and the split base station includes one or more distributed units, a central unit control plane, and one or more central unit user planes.

[0164] Data manager 820 can identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data. In some examples, data manager 820 can transmit a packet including the identified data and the at least one routing identifier in the inactive state. In some examples, data manager 820 can transmit the packet to the first network node. In some examples, data manager 820 can transmit the packet to an additional network node different from the first network node. In some examples, data manager 820 can receive downlink data from the additional network node based on transmitting the packet.

[0165] The PDU generation manager 825 may generate a protocol data unit that includes a sub - protocol data unit and a control element, the data unit includes the identified data, and the control element includes the at least one routing identifier, wherein transmitting the packet includes transmitting the generated protocol data unit.

[0166] In some examples, the PDU generation manager 825 may generate a protocol data unit that includes a set of sub - protocol data units, the set of sub - protocol data units includes sub - protocol data units, and each sub - protocol data unit in the set of sub - protocol data units corresponds to a respective routing identifier in the set of routing identifiers. In some examples, the control element is a media access control control element. In some cases, the protocol data unit is a media access control protocol data unit. In some cases, the sub - protocol data unit is a media access control sub - protocol data unit or a media access control service data unit.

[0167] The routing identifier manager 830 may receive an indication of a mapping between the set of routing identifiers and the set of data radio bearers, each routing identifier being mapped to at least one data radio bearer in the set of data radio bearers. In some examples, the routing identifier manager 830 may identify a data radio bearer associated with the data from the set of data radio bearers. In some examples, the routing identifier manager 830 may determine at least one routing identifier in the set of routing identifiers corresponding to the identified data radio bearer based on the received indication of the mapping.

[0168] The downlink monitoring manager 835 may receive a downlink monitoring timer in a connection release message. In some examples, the downlink monitoring manager 835 may identify a downlink monitoring window for an inactive state based on the received downlink monitoring timer. In some examples, the downlink monitoring manager 835 may monitor downlink transmissions during the downlink monitoring window in the inactive state.

[0169] The paging manager 840 may receive a paging message based on the monitoring. In some examples, the paging manager 840 may establish a radio connection based on the received paging message.

[0170] Figure 9FIG. 900 shows a diagram of a system 900 including a device 905 that supports small data transmissions to a decomposed base station in an inactive state in accordance with aspects of the present disclosure. The device 905 may be an example of a device 605, a device 705, or a UE 115 as described herein or include components of these devices. The device 905 may include components for two-way voice and data communication, including components for transmitting and receiving communications, including a communication manager 910, an I / O controller 915, a transceiver 920, an antenna 925, a memory 930, and a processor 940. These components may be in electronic communication via one or more buses (e.g., bus 945).

[0171] The communication manager 910 may receive a connection release message from a first network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; enter the inactive state based on receiving the connection release message; identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data; and transmit a packet including the identified data and the at least one routing identifier in the inactive state.

[0172] The I / O controller 915 may manage input and output signals of the device 905. The I / O controller 915 may also manage peripheral devices not integrated into the device 905. In some cases, the I / O controller 915 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 915 may utilize an operating system, such as or another known operating system. In other cases, the I / O controller 915 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, the I / O controller 915 may be implemented as part of a processor. In some cases, a user may interact with the device 905 via the I / O controller 915 or via hardware components controlled by the I / O controller 915.

[0173] The transceiver 920 may perform two-way communication via one or more antennas, wired or wireless links, as described above. For example, the transceiver 920 may represent a wireless transceiver and may perform two-way communication with another wireless transceiver. The transceiver 920 may also include a modem to modulate a packet and provide the modulated packet to the antenna for transmission, and to demodulate a packet received from the antenna.

[0174] In some cases, a wireless device may include a single antenna 925. However, in some cases, the device may have more than one antenna 925, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0175] The memory 930 may include RAM and ROM. The memory 930 may store computer-readable, computer-executable code 935 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 930 may particularly include a BIOS that may control basic hardware or software operations, such as interactions with peripheral components or devices.

[0176] The processor 940 may include intelligent hardware devices (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 940 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks supporting small data transmission to a decomposed base station in an inactive state).

[0177] The code 935 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communication. The code 935 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, the code 935 may not be directly executable by the processor 940, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0178] Figure 10 Block diagram 1000 of a device 1005 supporting small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is shown. The device 1005 may be an example of aspects of the base station 105 as described herein. The device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1020. The device 1005 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

[0179] The receiver 1010 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 small data transmission to a decomposed base station in an inactive state, etc.). The information may be passed to other components of the device 1005. The receiver 1010 may be an example of aspects of the transceiver 1320 described with reference to Figure 13 The receiver 1010 may utilize a single antenna or an antenna array.

[0180] The communication manager 1015 may transmit to the UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receive from the UE a packet including data and at least one routing identifier from the set of routing identifiers, at least in part in response to the transmitted connection release message; and transmit the data to a third network node based on the received at least one routing identifier. The communication manager 1015 may also transmit to a first network node a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and receive from the third network node an indication of data transmitted from the UE to the third network node, at least in part in response to the transmitted connection release message. The communication manager 1015 may be an example of aspects of the communication manager 1310 described herein.

[0181] The communication manager 1015 or its sub-components may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 1015 or its sub-components may be performed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC), an 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 this disclosure.

[0182] The communication manager 1015 or its sub-components may be physically located in various locations, including being distributed such that portions of the functions are implemented by one or more physical components in different physical locations. In some examples, in accordance with aspects of this disclosure, the communication manager 1015 or its sub-components may be separate and distinct components. In some examples, in accordance with various aspects of this disclosure, the communication manager 1015 or its sub-components may be combined with one or more other hardware components, the one or more other hardware components including, but not limited to, input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in this disclosure, or combinations thereof.

[0183] The transmitter 1020 may transmit signals generated by other components of the device 1005. In some examples, the transmitter 1020 may be co-located in a transceiver module with the receiver 1010. For example, the transmitter 1020 may be an example of aspects of the transceiver 1320 described with reference to Figure 13 The transmitter 1020 may utilize a single antenna or an antenna array.

[0184] Figure 11FIG. 1100 is a block diagram of device 1105 that supports small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure. Device 1105 may be an example of aspects of device 1005 or base station 105 as described herein. Device 1105 may include a receiver 1110, a communication manager 1115, and a transmitter 1130. Device 1105 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0185] The receiver 1110 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 small data transmission to a decomposed base station in an inactive state, etc.). The information may be passed to other components of device 1105. The receiver 1110 may be an example of aspects of transceiver 1320 described with reference to Figure 13 The receiver 1110 may utilize a single antenna or an antenna array.

[0186] The communication manager 1115 may be an example of aspects of communication manager 1015 as described herein. The communication manager 1115 may include a connection release manager 1120 and a data manager 1125. The communication manager 1115 may be an example of aspects of communication manager 1310 described herein.

[0187] The connection release manager 1120 may transmit to the UE a connection release message from a second network node instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer.

[0188] The data manager 1125 may receive, at least in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers from the UE, and transmit the data to a third network node based on the received at least one routing identifier.

[0189] The connection release manager 1120 may transmit to a first network node a connection release message instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer.

[0190] The data manager 1125 may receive, at least in response to the transmitted connection release message, an indication of data transmitted from the UE to the third network node from the third network node.

[0191] Transmitter 1130 may transmit signals generated by other components of device 1105. In some examples, transmitter 1130 may be co-located with receiver 1110 in a transceiver module. For example, transmitter 1130 may be an example of aspects of transceiver 1320 described with reference to Figure 13 Transmitter 1130 may utilize a single antenna or an antenna array.

[0192] Figure 12 FIG. 1200 is a block diagram of a communication manager 1205 that supports small data transfer to a split base station in an inactive state, according to aspects of the present disclosure. Communication manager 1205 may be an example of aspects of communication manager 1015, communication manager 1115, or communication manager 1310 described herein. Communication manager 1205 may include a connection release manager 1210, a data manager 1215, a PDU manager 1220, an address information manager 1225, a paging manager 1230, a DRB manager 1235, and a routing identifier manager 1240. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0193] The connection release manager 1210 may transmit to the UE a connection release message from a second network node instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer.

[0194] In some examples, the connection release manager 1120 may transmit to a first network node a connection release message instructing the UE to enter the inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer.

[0195] The data manager 1215 may receive, at least in response to the transmitted connection release message, a packet from the UE that includes data and at least one routing identifier from the set of routing identifiers. In some examples, the data manager 1215 may transmit the data to a third network node based on the received at least one routing identifier.

[0196] In some examples, the data manager 1215 may receive, at least in response to the transmitted connection release message, an indication from a third network node of data transmitted from the UE to the third network node. In some examples, a packet data convergence protocol (PDCP) protocol data unit (PPDU) is generated, where transmitting the data includes transmitting the PPDU along with address information.

[0197] In some examples, the data manager 1215 may receive an indication of downlink data for the UE transmitted from a third network node. In some examples, the data manager 1215 may receive an indication of uplink data from the UE, which is transmitted from a first network node to the third network node. In some examples, the data manager 1215 may transmit paging information to the first network node based on receiving the indication of the downlink data. In some cases, the first network node includes a distributed unit, wherein the second network node includes a control unit control plane, and wherein the third network node includes a control unit user plane. In some cases, the first network node includes a distributed unit, wherein the second network node includes a control unit control plane, and wherein the third network node includes a control unit user plane.

[0198] The PDU manager 1220 may receive a protocol data unit, which includes a sub-protocol data unit and a control element, the data unit includes the identified data, and the control element includes the at least one routing identifier, wherein transmitting the packet includes transmitting the generated protocol data unit.

[0199] In some examples, the control element is a media access control control element. In some cases, the protocol data unit includes a set of sub-protocol data units, the set of sub-protocol data units includes sub-protocol data units, and each sub-protocol data unit in the set of sub-protocol data units corresponds to a corresponding routing identifier in the set of routing identifiers.

[0200] In some cases, the protocol data unit is a media access control protocol data unit. In some cases, the sub-protocol data unit is a media access control sub-protocol data unit or a media access control service data unit.

[0201] The address information manager 1225 may determine the address information of the third network node based on the at least one routing identifier, wherein transmitting the data to the third network node is based on the determined address information. In some cases, the address information includes an uplink tunnel identifier, a transport network layer address, or a combination thereof.

[0202] The paging manager 1230 may receive paging information from the second network node. In some examples, the paging manager 1230 may transmit the paging information to the UE based on the at least one routing identifier.

[0203] The DRB manager 1235 may transmit a bearer modification request message to a third network node. In some examples, the DRB manager 1235 may receive a bearer modification response message from the third network node in response to the bearer modification request message, wherein transmitting the connection release message is based on the received bearer modification response message.

[0204] In some examples, the DRB manager 1235 may determine, for a UE, a set of data radio bearers including at least one data radio bearer for use in an inactive state of the UE. In some examples, the DRB manager 1235 may identify a set of routing identifiers associated with the data radio bearer, wherein transmitting the connection release message is based on identifying the set of routing identifiers. In some cases, the bearer modification request message includes an indication of a set of suspended data radio bearers and a set of non-suspended data radio bearers, the set of non-suspended data radio bearers including the at least one data radio bearer.

[0205] The routing identifier manager 1240 may determine that the bearer modification response message includes an indication of the set of routing identifiers and a set of data radio bearer identifiers associated with the set of routing identifiers.

[0206] Figure 13 FIG. shows a diagram of a system 1300 including an apparatus 1305 that supports small data transfer to a split base station in an inactive state in accordance with aspects of the present disclosure. The apparatus 1305 may be an example of, or include components of, the apparatus 1005, apparatus 1105, or base station 105 described herein. The apparatus 1305 may include components for two-way voice and data communication, which includes components for transmitting and receiving communications, including a communication manager 1310, a network communication manager 1315, a transceiver 1320, an antenna 1325, a memory 1330, a processor 1340, and an inter-station communication manager 1345. These components may be in electronic communication via one or more buses (e.g., bus 1350).

[0207] The communication manager 1310 may transmit to the UE an instruction from a second network node to enter an inactive state a connection release message, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receive from the UE at least in part in response to the transmitted connection release message a packet including data and at least one routing identifier in the set of routing identifiers; and transmit data to a third network node based on the received at least one routing identifier. The communication manager 1310 may also transmit to a first network node a connection release message indicating that the UE enters an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; and receive from the third network node at least in part in response to the transmitted connection release message an indication of data transmitted from the UE to the third network node.

[0208] The network communication manager 1315 may manage communication with the core network (e.g., via one or more wired backhaul links). For example, the network communication manager 1315 may manage the delivery of data communication of client devices (such as one or more UEs 115).

[0209] The transceiver 1320 may perform two-way communication via one or more antennas, wired or wireless links, as described above. For example, the transceiver 1320 may represent a wireless transceiver and may perform two-way communication with another wireless transceiver. The transceiver 1320 may also include a modem to modulate a packet and provide the modulated packet to the antenna for transmission, and to demodulate a packet received from the antenna.

[0210] In some cases, the wireless device may include a single antenna 1325. However, in some cases, the device may have more than one antenna 1325, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0211] The memory 1330 may include RAM, ROM, or a combination thereof. The memory 1330 may store computer-readable code 1335 including instructions, which when executed by a processor (e.g., processor 1340) cause the device to perform the various functions described herein. In some cases, the memory 1330 may in particular contain BIOS, which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0212] The processor 1340 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 1340 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into the processor 1340. The processor 1340 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1330) to cause the device 1305 to perform various functions (e.g., support functions or tasks for small data transmission to a decomposed base station in an inactive state).

[0213] The inter-station communication manager 1345 may manage communication with other base stations 105 and may include a controller or scheduler for collaboratively controlling communication with the UE 115 with other base stations 105. For example, the inter-station communication manager 1345 may coordinate the scheduling of transmissions to the UE 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communication manager 1345 may provide an X2 interface within the LTE / LTE-A wireless communication network technology to provide communication between the base stations 105.

[0214] The code 1335 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communication. The code 1335 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, the code 1335 may not be directly executed by the processor 1340, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0215] Figure 14 A flowchart illustrating a method 1400 for supporting small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is shown. The operations of the method 1400 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 1400 may be performed by a communication manager as described with reference to Figures 6 to 9 described. In some examples, the UE may execute an instruction set to control functional elements of the UE to perform the following functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the following functions.

[0216] At 1405, the UE may receive a connection release message from a first network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer. The operation of 1405 may be performed according to the methods described herein. In some examples, aspects of the operation of 1405 may be performed by a communication manager as described with reference toFigures 6 to 9 Execute using the described connection release manager.

[0217] At 1410, the UE may enter an inactive state based on receiving the connection release message. The operation of 1410 may be performed according to the methods described herein. In some examples, aspects of the operation of 1410 may be performed by, such as, referring to Figures 6 to 9 The described connection state manager.

[0218] At 1415, the UE may identify data to be transmitted in the inactive state of the UE and at least one routing identifier associated with the data in the set of routing identifiers. The operation of 1415 may be performed according to the methods described herein. In some examples, aspects of the operation of 1415 may be performed by, such as, referring to Figures 6 to 9 The described data manager.

[0219] At 1420, the UE may transmit a packet including the identified data and the at least one routing identifier in the inactive state. The operation of 1420 may be performed according to the methods described herein. In some examples, aspects of the operation of 1420 may be performed by, such as, referring to Figures 6 to 9 The described data manager.

[0220] Figure 15 A flowchart illustrating a method 1500 for supporting small data transmission to a decomposed base station in an inactive state in accordance with aspects of the present disclosure is shown. The operations of method 1500 may be implemented by the base station 105 or its components as described herein. For example, the operations of method 1500 may be performed by, such as, referring to Figures 10 to 13 The described communication manager. In some examples, the base station may execute an instruction set to control functional elements of the base station to perform the following functions. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the following functions.

[0221] At 1505, the base station may transmit to the UE a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer. The operation of 1505 may be performed according to the methods described herein. In some examples, aspects of the operation of 1505 may be performed by, such as, referring to Figures 10 to 13 The described connection release manager.

[0222] At 1510, the base station may receive, at least in part in response to the transmitted connection release message, a packet including data and at least one routing identifier from the set of routing identifiers. The operation of 1510 may be performed according to the methods described herein. In some examples, aspects of the operation of 1510 may be performed by a data manager as described with reference to Figures 10 to 13 as described.

[0223] At 1515, the base station may transmit the data to a third network node based on the at least one received routing identifier. The operation of 1515 may be performed according to the methods described herein. In some examples, aspects of the operation of 1515 may be performed by a data manager as described with reference to Figures 10 to 13 as described.

[0224] Figure 16 A flowchart illustrating a method 1600 for supporting small data transmission to a split base station in an inactive state in accordance with aspects of the present disclosure is shown. The operations of method 1600 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1600 may be performed by a communication manager as described with reference to Figures 10 to 13 as described. In some examples, the base station may execute an instruction set to control functional elements of the base station to perform the following functions. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the following functions.

[0225] At 1605, the base station may transmit a connection release message instructing the UE to enter an inactive state to a first network node, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer. The operation of 1605 may be performed according to the methods described herein. In some examples, aspects of the operation of 1605 may be performed by a connection release manager as described with reference to Figures 10 to 13 as described.

[0226] At 1610, the base station may receive, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to the third network node from the third network node. The operation of 1610 may be performed according to the methods described herein. In some examples, aspects of the operation of 1610 may be performed by a data manager as described with reference to Figures 10 to 13 as described.

[0227] It should be noted that the methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise modified and other implementations are possible. Additionally, aspects from two or more methods may be combined.

[0228] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in much of the description, the techniques described herein may also be applied to networks other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applied to a variety of other wireless communication systems such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0229] The information and signals described herein may be represented using any of a variety of different arts and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout this description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0230] The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, DSP, ASIC, CPU, FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0231] The functions described herein 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 may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations fall within the scope of the disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software, hardware, firmware, hardwired, or any combination thereof executed by a processor. The features implementing the functions may also be physically located in various places, including being distributed such that portions of the functions are implemented at different physical locations.

[0232] A computer-readable medium includes both a non-transitory computer storage medium and a communication medium including any medium that facilitates transfer of a computer program from one place to another. The non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random access memory (RAM), read only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Likewise, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. As used herein, the terms "disk" and "disc" include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically and discs reproduce data optically with lasers. Combinations of the above media are also included within the scope of computer-readable media.

[0233] As used herein, including in the claims, the term "or" as used in a list of items (e.g., a list of items prefaced with a phrase such as "at least one of" or "one or more of") indicates an inclusive listing such that, for example, a listing of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Likewise, as used herein, the phrase "based on" should not be construed as limiting to a closed set of conditions. For example, an example step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0234] In the figures, like components or features may have the same reference numerals. Additionally, each of the same type of components may be distinguished by following the reference numeral with a dash and a second label that differentiates among the similar components. If only the first reference numeral is used in the specification, the description may apply to any one of the similar components having the same first reference numeral regardless of the second reference numeral, or any other subsequent reference numerals.

[0235] The description provided herein with reference to the accompanying drawings describes example configurations and does not represent all examples that may be implemented or fall within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration" and does not mean "superior to" or "better than" other examples. This detailed description includes specific details to provide an understanding of the described technologies. However, the technologies may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0236] The description herein is provided to enable a person of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to a person of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: Receiving, from a first network node, a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer, wherein the receiving further includes receiving an indication of a mapping between the set of routing identifiers and a set of data radio bearers, each routing identifier being mapped to at least one data radio bearer in the set of data radio bearers; Entering the inactive state at least in part based on receiving the connection release message; Identifying data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data, wherein the identifying further includes: Identifying, from the set of data radio bearers, a data radio bearer associated with the data; and Determining, at least in part based on the received indication of the mapping, the at least one routing identifier in the set of routing identifiers corresponding to the identified data radio bearer; and Transmitting, in the inactive state, a packet including the identified data and the at least one routing identifier.

2. The method according to claim 1, further comprising: Generating a protocol data unit, the protocol data unit including a sub-protocol data unit and a control element, the sub-protocol data unit including the identified data, and the control element including the at least one routing identifier, wherein transmitting the packet includes transmitting the generated protocol data unit.

3. The method according to claim 2, wherein generating the protocol data unit further includes: Generating the protocol data unit, the protocol data unit including a set of sub-protocol data units, the set of sub-protocol data units including the sub-protocol data unit, each sub-protocol data unit in the set of sub-protocol data units corresponding to a respective routing identifier in the set of routing identifiers.

4. The method according to claim 2, wherein: The protocol data unit includes a media access control protocol data unit; The sub-protocol data unit includes a media access control sub-protocol data unit or a media access control service data unit; and The control element includes a media access control control element.

5. The method according to claim 1, wherein transmitting the packet includes: Transmitting the packet to the first network node.

6. The method according to claim 1, wherein transmitting the packet includes: Transmitting the packet to an additional network node different from the first network node; And Receiving downlink data from the additional network node at least in part based on transmitting the packet.

7. The method according to claim 1, further comprising: Receiving a downlink monitoring timer in the connection release message.

8. The method according to claim 7, further comprising: Identifying a downlink monitoring window for the inactive state at least in part based on the received downlink monitoring timer; And Monitor downlink transmissions during the downlink monitoring window in the inactive state.

9. The method according to claim 8, further comprising: Receiving a paging message at least in part based on the monitoring; And Establishing a wireless connection at least in part based on the received paging message.

10. The method according to claim 1, wherein: The connection release message includes a radio resource control release message; The wireless connection between the UE and the first network node includes a radio resource control connection; and The inactive state includes a radio resource control inactive state.

11. The method according to claim 1, wherein the first network node includes a distributed unit of a split base station, and the split base station includes one or more distributed units, a central unit control plane, and one or more central unit user planes.

12. A method for wireless communication at a first network node, comprising: Transmitting to a user equipment (UE) a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; Receiving from the UE at least in part in response to the transmitted connection release message a packet including data and at least one routing identifier from the set of routing identifiers; Determining address information of a third network node at least in part based on the at least one routing identifier, wherein transmitting the data to the third network node is at least in part based on the determined address information; And Transmitting the data to the third network node at least in part based on the received at least one routing identifier.

13. The method according to claim 12, wherein receiving the data packet comprises: Receiving a protocol data unit, the protocol data unit including a sub-protocol data unit and a control element, the sub-protocol data unit including the identified data, and the control element including the at least one routing identifier, wherein transmitting the packet comprises transmitting the generated protocol data unit.

14. The method according to claim 13, wherein the protocol data unit includes a set of sub-protocol data units, the set of sub-protocol data units including the sub-protocol data unit, and each sub-protocol data unit in the set of sub-protocol data units corresponds to a respective routing identifier in the set of routing identifiers.

15. The method according to claim 13, wherein: The protocol data unit includes a media access control protocol data unit; The sub-protocol data unit includes a media access control sub-protocol data unit or a media access control service data unit; and The control element includes a media access control control element.

16. The method according to claim 12, wherein the address information includes an uplink tunnel identifier, a transport network layer address, or a combination thereof.

17. The method according to claim 12, wherein: Generate a Packet Data Convergence Protocol (PDCP) protocol data unit (PPDU), wherein transmitting the data includes transmitting the PPDU together with the address information.

18. The method according to claim 12, further comprising: Receiving paging information from the second network node; And Transmitting the paging information to the UE at least in part based on the at least one routing identifier.

19. The method according to claim 12, wherein the first network node includes a distributed unit, the second network node includes a control unit control plane, and the third network node includes a control unit user plane.

20. A method for wireless communication at a second network node, comprising: Determining, for a user equipment (UE), a set of data radio bearers including at least one data radio bearer for use in an inactive state of the UE; Identifying routing identifiers in a set of routing identifiers associated with the data radio bearers; Transmitting a connection release message instructing the UE to enter an inactive state to a first network node, the connection release message including the set of routing identifiers, each routing identifier in the set of routing identifiers being associated with the at least one data radio bearer, wherein transmitting the connection release message is at least in part based on identifying the set of routing identifiers; And Receiving, at least in part in response to the transmitted connection release message, an indication of data transmitted from the UE to the third network node from the third network node.

21. The method according to claim 20, further comprising: Transmitting a bearer modification request message to the third network node; And Receiving a bearer modification response message from the third network node in response to the bearer modification request message, wherein transmitting the connection release message is at least in part based on the received bearer modification response message.

22. The method according to claim 21, wherein: The bearer modification request message includes an indication of a set of suspended data radio bearers and a set of non-suspended data radio bearers, the set of non-suspended data radio bearers including the at least one data radio bearer; and The bearer modification response message includes an indication of the set of routing identifiers and a set of data radio bearer identifiers associated with the set of routing identifiers.

23. The method according to claim 20, further comprising: Receiving an indication of downlink data for the UE transmitted from the third network node from the third network node; And Transmitting paging information to the first network node at least in part based on receiving the indication of the downlink data.

24. The method according to claim 20, further comprising: Receiving an indication of uplink data from the UE, the uplink data being transmitted from the first network node to the third network node, from the third network node.

25. The method according to claim 20, wherein the first network node comprises a distributed unit, wherein the second network node comprises a control unit control plane, and wherein the third network node comprises a control unit user plane.

26. An apparatus for wireless communication at a user equipment (UE), comprising: a processor, a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: receive from a first network node a connection release message instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer, wherein the receiving further comprises receiving an indication of a mapping between the set of routing identifiers and a set of data radio bearers, each routing identifier being mapped to at least one data radio bearer in the set of data radio bearers; enter the inactive state at least in part based on receiving the connection release message; identify data to be transmitted in the inactive state of the UE and at least one routing identifier in the set of routing identifiers associated with the data, wherein the identifying further comprises: identifying a data radio bearer associated with the data from the set of data radio bearers; and determining at least one routing identifier in the set of routing identifiers corresponding to the identified data radio bearer at least in part based on the received indication of the mapping; and transmit a packet in the inactive state including the identified data and the at least one routing identifier.

27. The apparatus according to claim 26, wherein the instructions are further executable by the processor to cause the apparatus to: instructions for generating a protocol data unit including a sub-protocol data unit and a control element, the sub-protocol data unit including the identified data, and the control element including the at least one routing identifier, wherein transmitting the packet is executable by the processor to cause the apparatus to transmit the generated protocol data unit.

28. The apparatus according to claim 27, wherein the instructions for generating the protocol data unit are further executable by the processor to cause the apparatus to: generate the protocol data unit including a set of sub-protocol data units, the set of sub-protocol data units including the sub-protocol data unit, each sub-protocol data unit in the set of sub-protocol data units corresponding to a respective routing identifier in the set of routing identifiers.

29. The apparatus according to claim 27, wherein: the protocol data unit comprises a media access control protocol data unit; the sub-protocol data unit comprises a media access control sub-protocol data unit or a media access control service data unit; and the control element comprises a media access control control element.

30. The apparatus according to claim 26, wherein the instructions for transmitting the packet are executable by the processor to cause the apparatus to: Transmit the packet to the first network node.

31. An apparatus for wireless communication at a user equipment (UE), comprising: a processor, a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the operations of the method according to any one of claims 7 - 11.

32. An apparatus for wireless communication at a first network node, comprising: a processor, a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: transmit to a user equipment (UE) a connection release message from a second network node instructing the UE to enter an inactive state, the connection release message including a set of routing identifiers, each routing identifier in the set of routing identifiers being associated with at least one data radio bearer; receive from the UE a packet including data and at least one routing identifier from the set of routing identifiers, at least in part in response to the transmitted connection release message; determine address information of a third network node, at least in part based on the at least one routing identifier, wherein transmitting the data to the third network node is at least in part based on the determined address information; and transmit the data to the third network node, at least in part based on the received at least one routing identifier.

33. An apparatus for wireless communication at a first network node, comprising: a processor, a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the operations of the method according to any one of claims 13 - 19.

34. An apparatus for wireless communication at a second network node, comprising: a processor, a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the operations of the method according to any one of claims 20 - 25.

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