Managing pending data in inactive scenarios

Abstract

A method is disclosed for communicating with a base station when a UE is operating (702) in an inactive state associated with a protocol for controlling radio resources in the UE. The UE is configured to (i) transmit data of a first channel using a first procedure that causes the UE to transition to a connected state associated with the protocol, and (ii) transmit data of a second channel using a second procedure that does not cause the UE to transition to the connected state. The method includes detecting (704) pending data addressed to the base station, the pending data including first data of the first channel and second data of the second channel. The method further includes selecting (706) the first procedure or the second procedure based on comparing a priority of the first channel with a priority of the second channel, and transmitting (708) at least a portion of the pending data using the selected procedure.

Description

Technical Field

[0001] This disclosure relates to wireless communications, and more specifically, to techniques for managing small data transmission (SDT). Background Technology

[0002] The background description provided herein is for the purpose of presenting the overall context of this disclosure. The work of the currently attributed inventors, to the extent described in the background section and in aspects that may not qualify as prior art at the time of filing, is neither expressly nor implicitly acknowledged as prior art to this disclosure.

[0003] In telecommunications systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data transmission, encryption, and integrity protection. For example, the PDCP layer, defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323), provides the ordering of Protocol Data Units (PDUs) in the uplink direction (from the user equipment, also known as the UE, to the base station) and the downlink direction (from the base station to the UE). Furthermore, the PDCP sublayer provides Signaling Radio Bearer (SRB) services to the Radio Resource Control (RRC) sublayer. The PDCP sublayer also provides Data Radio Bearer (DRB) services to the Serving Data Adaptation Protocol (SDAP) sublayer or protocol layers such as the Internet Protocol (IP) layer, Ethernet layer, and Internet Control Message Protocol (ICMP) layer. Generally, the UE and base station can use SRBs to exchange RRC messages and Non-Access Stratum (NAS) messages, and can use DRBs to transmit data on the user plane.

[0004] UEs can use several types of SRBs and DRBs. When operating under dual connectivity (DC), the cell associated with the base station operating as the primary node (MN) defines a primary cell group (MCG), and the cell associated with the base station operating as the secondary node (SN) defines a secondary cell group (SCG). The so-called SRB1 resource carries RRC messages, which in some cases include NAS messages, and is transmitted via the dedicated control channel (DCCH); and the SRB2 resource supports RRC messages including recorded measurement information or NAS messages, also transmitted via the DCCH but with a lower priority than the SRB1 resource. More generally, the SRB1 and SRB2 resources allow the UE and MN to exchange MN-related RRC messages and embed SN-related RRC messages, and can also be referred to as MCG SRBs. The SRB3 resource allows the UE and SN to exchange SN-related RRC messages and can be referred to as SCG SRBs. Segmented SRBs allow the UE to exchange RRC messages directly with the MN via lower-layer resources of the MN and SN. Furthermore, a DRB that terminates at MN and uses only the lower-level resources of MN can be called an MCG DRB, a DRB that terminates at SN and uses only the lower-level resources of SN can be called an SCG DRB, and a DRB that terminates at MCG but uses the lower-level resources of MN, SN, or both MN and SN can be called a split DRB.

[0005] In some scenarios, a UE can simultaneously utilize the resources of multiple nodes (e.g., base stations or components of a distributed base station) in a radio access network (RAN) interconnected via backhaul. In these scenarios, the UE is considered to be operating under multiple connectivity (MC) with multiple nodes. For example, when a UE utilizes the resources of two network nodes simultaneously, it is considered to be operating under dual connectivity with both network nodes. When these network nodes support different radio access technologies (RATs), such as 5G NR and EUTRA, this type of connectivity is called multiple radio dual connectivity (MR-DC). When the UE operates under MR-DC, one base station operates as the MN covering the primary cell (PCell), and the other base station operates as the SN covering the primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and the SN (via the PSCell). In other scenarios, the UE utilizes the resources of one base station at a time. One base station and / or the UE determines that the UE should establish a radio connection with another base station. For example, one base station may determine to hand over the UE to a second base station and initiate a handover procedure. In other scenarios, the UE can simultaneously utilize the resources of RAN nodes (e.g., components of a single base station or a distributed base station) that are interconnected to other network elements via backhaul.

[0006] The MN can provide control plane and user plane connections to the core network (CN), while the SN typically provides user plane connections. In some cases, the base station (e.g., MN, SN) and / or CN transitions the UE from one state of the RRC protocol to another. More specifically, the UE can operate in an idle state (e.g., EUTRA-RRC_IDLE, NR-RRC_IDLE), where the UE does not have a radio connection with the base station; it can operate in a connected state (e.g., EUTRA-RRC_CONNECTED, NR-RRC CONNECTED), where the UE has a radio connection with the base station; or it can operate in an inactive state (e.g., EUTRA-RRCINACTIVE, NR-RRC INACTIVE), where the UE has a suspended radio connection with the base station.

[0007] By operating in an inactive state, the UE can conserve power compared to the connected state. Because the UE suspends its radio connection rather than releasing it, it can quickly restore the connection to communicate with the base station. Furthermore, certain recently introduced techniques, such as Early Data Transmission and Small Data Transmission (SDT), allow the UE to transmit data while operating in an inactive state. Configuration-based authorization (CG) SDT and random access (RA)-based SDT schemes generally allow the UE to communicate with the base station during inactive periods. Alternatively, the UE can transmit data by transitioning to the connected state, such as by performing a conventional random access procedure to restore the radio connection.

[0008] The base station can configure the UE to perform SDT on a per-channel basis. Thus, based on the channel configuration (such as a logical channel or DRB), the UE determines whether to use SDT or a conventional procedure to transmit pending data for that channel. However, when the UE simultaneously has pending data for multiple channels with different configurations, it is unclear how the UE should transmit the pending data. Summary of the Invention

[0009] A UE operating in an inactive state can implement the techniques of this disclosure to select a process for transmitting data to be processed when the data to be processed includes data for channels with different configurations. Initially, the UE can receive configurations for multiple channels from a base station. Each configuration indicates (i) the priority of the corresponding channel and (ii) whether to use a first process that puts the UE into a connected state (e.g., a conventional RA process) or a second process that does not put the UE into a connected state (e.g., SDT) to transmit data for the corresponding channel.

[0010] If the UE detects pending data on two channels, it can select which procedure to use to transmit the pending data based on the relative priority of the two channels. If one channel has a higher priority than the other, the UE can select the procedure associated with the higher-priority channel to transmit the data for that channel. If the two channels have the same priority, the UE can prioritize transmitting the data for the channel associated with the second procedure.

[0011] If the UE selects the second procedure, it may further need to select the type of SDT to utilize. The UE can check whether it has already configured a CG for the time resource corresponding to the next transmission opportunity. If so, the UE can utilize the CG to transmit the pending data for the second channel. Otherwise, the UE can perform an RA-based SDT, or it can wait until it does indeed have a later transmission opportunity with a CG.

[0012] When a UE initiates an RA procedure, it can specify to the base station whether it is performing an RA-based SDT or a traditional RA procedure. The base station allocates different RA resources (i.e., different preambles and / or different physical RA channel (PRACH) timings) for RA-based SDT and traditional RA procedures. To indicate whether the UE has selected RA-based SDT or traditional RA, the UE uses the RA resources corresponding to the selected procedure.

[0013] Furthermore, in some implementations, the UE detects the Media Access Control (MAC) control element (CE) used for transmission to the base station, but does not detect the data to be processed. In response, the UE can use the SDT to send a MAC CE.

[0014] An example embodiment of these technologies is a method implemented in a UE for communicating with a base station when the UE is operating in an inactive state associated with a protocol for controlling radio resources. The UE is configured to: (i) transmit data on a first channel using a first procedure that transitions the UE to a connected state associated with the protocol, and (ii) transmit data on a second channel using a second procedure that does not transition the UE to a connected state. The method can be executed by processing hardware and includes detecting pending data addressed to a base station, the pending data including first data on the first channel and second data on the second channel. The method further includes: selecting either the first procedure or the second procedure based on a comparison of the priority of the first channel with the priority of the second channel, and having the processing hardware transmit at least a portion of the pending data using the selected procedure.

[0015] Another example embodiment of these technologies is a UE that includes processing hardware and is configured to implement the methods described above. Attached Figure Description

[0016] Figure 1 This is a block diagram of an example system in which base stations and user equipment (UEs) of a radio access network (RAN) can implement the techniques of this disclosure for transmitting data when operating in an inactive state.

[0017] Figure 2 yes Figure 1 The UE is based on a block diagram of an example protocol stack for communicating with the base station;

[0018] Figure 3A This is a message passing diagram for an example scenario where a UE operating in inactive mode detects uplink data on the first and second channels. The UE is configured to send data on the second channel using Small Data Transmission (SDT) and send data on the first channel using a non-SDT procedure. The UE determines whether to use SDT based on the relative priority of the first and second channels.

[0019] Figure 3B It is similar to Figure 3A The following is a message passing diagram of an example scenario where the UE determines to use configuration-based authorization (CG) SDT;

[0020] Figure 3C It is similar to Figure 3A The example scenario is a message passing diagram where the UE determines to wait for the next available CG in order to use CG-based SDT;

[0021] Figure 3D It is similar to Figure 3A The following is a message passing diagram of an example scenario where the UE determines to use SDT based on random access (RA);

[0022] Figure 4 It is similar to Figure 3A The example scenario is a message passing diagram, but in which the UE determines to use SDT based on the fact that the first channel and the second channel have the same priority;

[0023] Figure 5 This is a flowchart of an example method for transmitting a Media Access Control (MAC) control element (CE) when operating in an inactive mode, which can be implemented by the UE of this disclosure;

[0024] Figure 6 This is a flowchart of an example method for transitioning from RA-based SDT to traditional RA procedures when operating in inactive mode, which can be implemented by the UE of this disclosure; and

[0025] Figure 7 This is a flowchart of an exemplary method for communicating with a base station when operating in an inactive mode, which can be implemented by the UE of this disclosure. Detailed Implementation

[0026] Figure 1 An example wireless communication system 100 that can implement the techniques of this disclosure is depicted. The wireless communication system 100 includes a UE 102, a base station 104, a base station 106, and a core network (CN) 110. The techniques of this disclosure can be implemented in the UE 102 or in one or both of the base stations 104 and 106.

[0027] Base stations 104 and 106 can be any suitable type of base station, such as an evolved Node B (eNB), a next-generation eNB (ng-eNB), or a 5G Node B (gNB). UE 102 can communicate with base stations 104 and 106 via the same Radio Access Technology (RAT) (such as EUTRA or NR) or a different RAT. Base station 104 supports cell 124, and base station 106 supports cell 126. Cells 124 and 126 partially overlap, allowing UE 102 to be within range of communication with base station 104 while simultaneously being within range of communication with base station 106 (or within range of detecting or measuring signals from base station 106). This overlap allows UE 102 to handover between cells (e.g., from cell 124 to cell 126) or base stations (e.g., from base station 104 to base station 106). As another example, UE 102 can communicate with base station 104 (operating as MN) and base station 106 (operating as SN) under dual connectivity (DC).

[0028] Base stations 104 and 106 operate within a radio access network (RAN) 105 connected to a CN 110, which can be an evolved packet core (EPC) 111 or a fifth-generation core (5GC) 160. Base station 104 can be implemented as an eNB supporting an S1 interface for communication with the EPC 111, an ng-eNB supporting an NG interface for communication with the 5GC 160, or a gNB supporting both an NR radio interface and an NG interface for communication with the 5GC 160. Base station 106 can be implemented as an eNB with an S1 interface to the EPC 111, an ng-eNB not connected to the EPC 111, a gNB supporting both an NR radio interface and an NG interface to the 5GC 160, or an ng-eNB supporting both an EUTRA radio interface and an NG interface to the 5GC 160. For direct message exchange in the scenarios discussed below, base stations 104 and 106 can support X2 or Xn interfaces.

[0029] In addition to other components, EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. SGW 112 is typically configured to transmit user plane packets related to audio calls, video calls, Internet services, etc., and MME 114 is configured to manage authentication, registration, paging, and other related functions. PGW 116 provides connectivity from the UE to one or more external packet data networks (e.g., Internet networks and / or Internet Protocol (IP) Multimedia Subsystem (IMS) networks). 5GC 160 includes a User Plane Function (UPF) 162 and Access and Mobility Management (AMF) 164 and / or Session Management Function (SMF) 166. UPF 162 is typically configured to transmit user plane packets related to audio calls, video calls, Internet services, etc., AMF 164 is configured to manage authentication, registration, paging, and other related functions, and SMF 166 is configured to manage PDU sessions.

[0030] Typically, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or 5GC 160 may connect to any suitable number of base stations supporting NR cells and / or EUTRA cells. Although the examples below specifically relate to particular CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques disclosed herein can also be applied to other suitable radio access and / or core network technologies, such as sixth-generation (6G) radio access and / or 6G core network or 5G NR-6G DC.

[0031] Continue to refer to Figure 1 The base station 104 includes processing hardware 130, which may include one or more general-purpose processors (e.g., central processing unit (CPU)) and computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or dedicated processing units. Figure 1 In the example implementation, processing hardware 130 includes a base station SDT controller 132, which is configured to support the techniques of this disclosure, as described below. Similarly, base station 106 is equipped with processing hardware 140 and base station SDT controller 142, which are similar to processing hardware 130 and SDT controller 132, respectively.

[0032] UE 102 includes processing hardware 150, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions that can be executed on a general-purpose processor and / or a dedicated processing unit. Figure 1The processing hardware 150 in the example implementation includes a UE SDT controller 152, which is configured to support the techniques of this disclosure, as described below.

[0033] Next, Figure 2 An example protocol stack 200 is shown in a simplified manner, according to which UE 102 can communicate with an eNB / ng-eNB or gNB (e.g., one or both of base stations 104 and 106).

[0034] In example stack 200, the EUTRA physical layer (PHY) 202A provides a transport channel to the EUTRA MAC sublayer 204A, which in turn provides a logical channel to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A then provides an RLC channel to the EUTRA PDCP sublayer 208, and in some cases, to the NR PDCP sublayer 210. Similarly, the NR PHY 202B provides a transport channel to the NR MAC sublayer 204B, which in turn provides a logical channel to the NR RLC sublayer 206B. The NR RLC sublayer 206B then provides an RLC channel to the NR PDCP sublayer 210. In some implementations, UE 102 supports, for example... Figure 2 The EUTRA and NR stacks shown are designed to support handover between EUTRA and NR base stations and / or support DC on the EUTRA and NR interfaces. Additionally, as... Figure 2 As shown, UE 102 can support the layering of NR PDCP210 on EUTRA RLC 206A and SDAP sublayer 212 on NR PDCP sublayer 210.

[0035] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 (e.g., from an Internet Protocol (IP) layer that is directly or indirectly layered on PDCP layer 208 or 210) receive packets that can be referred to as Service Data Units (SDUs), and (e.g., to RLC layer 206A or 206B) output packets that can be referred to as Protocol Data Units (PDUs). Except where the difference between SDU and PDU is relevant, for simplicity, this disclosure refers to both SDU and PDU as "packets".

[0036] On the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide SRBs to exchange, for example, RRC messages or Non-Access Stratum (NAS) messages. On the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide DRBs to support data exchange. The data exchanged on NR PDCP sublayer 210 can be SDAP PDUs, Internet Protocol (IP) packets, or Ethernet packets.

[0037] Figure 3A-4 This is a message passing diagram for an example scenario, where the base station and UE implement the techniques of this disclosure for managing pending data in inactive mode scenarios. Generally speaking, Figures 3A to 4 Similar events are labeled with similar reference numerals (e.g., event 310A is similar to events 310B, 310C, 310D, and 410), which have the differences discussed where appropriate. Apart from the differences shown in the figures and discussed below, any alternative implementations discussed with respect to specific events (e.g., those for messaging and processing) may be applied to events labeled with similar reference numerals in other figures.

[0038] First go to Figure 3A During scenario 300A, UE 102 communicates with base station 104. Initially, base station 104 sends a 302A configuration message to UE 102. The information included in the configuration message may vary depending on the implementation. The configuration message includes at least one or more configuration grants (CGs). CGs include radio resource configurations (e.g., time and / or frequency resources, periodicity, etc.) for scheduled uplink transmissions. Each CG may also be associated with a beam (i.e., spatial configuration).

[0039] The configuration message also includes random access (RA) resources for UE 102 to initiate a random access procedure with base station 104. The random access resources may include one or both of (a) a first type of random access resources for performing a conventional random access procedure (i.e., a non-SDT random access procedure) and (b) a second type of random access resources for performing RA-based SDT. The first type of random access resources includes a random access preamble and / or a physical random access channel (PRACH) timing for performing a conventional random access procedure that causes UE 102 to transition to a connected state. The PRACH timing is the timing at which UE 102 can send a random access preamble to initiate a random access procedure. The second type of random access resources includes a random access preamble and / or a PRACH timing dedicated to use in an inactive state. Specifically, the RA preamble and / or PRACH timing may be dedicated to performing RA-based SDT, which does not cause UE 102 to transition to a connected state.

[0040] The configuration message also includes configurations for two or more channels, comprising at least a first channel configuration for a first channel and a second channel configuration for a second channel. The first channel configuration indicates that data for the first channel should be transmitted using a non-SDT procedure (e.g., a conventional random access procedure) and indicates the first channel priority. Similarly, the second channel configuration indicates that data for the second channel should be transmitted using an SDT procedure and indicates the second channel priority.

[0041] Following or in response to a configuration message, UE 102 initiates operation in an inactive state in event 304A. For example, the configuration message may be an RRC message, such as an RRCRelease message or an RRCReject message, that causes UE 102 to transition to an inactive state. While event 304A refers to UE 102 transitioning to an inactive state (e.g., RRC_INACTIVE), alternatively, UE 102 may transition to another state where the UE does not have an active radio connection, such as an idle state with a suspended radio connection (e.g., RRC_IDLE). Embodiments of this disclosure are generally applicable to both idle states with a suspended radio connection and inactive states. Events 302A and 304A are collectively referred to in this disclosure as Inactive State Initiation Procedure 310A.

[0042] Next, UE 102 detects the first data on the first channel (312A) and the second data on the second channel (314A). For example, UE 102 can detect the first data in the data buffer of the first channel (312A) and the second data in the data buffer of the second channel (314A). Therefore, UE 102 has data to be processed that includes both the first data and the second data. To determine which procedure to use to send the data to be processed, UE 102 determines whether the priority of the second channel (315A) is higher than the priority of the first channel. If the priority of the second channel is higher than the priority of the first channel, then UE 102 determines that the second data will be sent using the SDT procedure (318A). Later, UE 102 can use the conventional random access procedure (SART) to send the first data. However, because (i) the priority of the second channel is higher than the priority of the first channel, and (ii) the second data on the second channel can be sent via SDT, UE 102 preferentially uses SDT to send the second data.

[0043] If the second channel priority is lower than the first channel priority, UE 102 performs the 340A legacy random access procedure to transmit pending data. UE 102 can transmit pending data during the legacy random access procedure and after or in response to the legacy random access procedure transitioning to the connected state. The legacy random access procedure can be a four-step or two-step random access procedure. When initiating a legacy random access procedure, UE 102 uses the random access resources (i.e., random access preamble or PRACH timing) included in the first type of random access resources discussed above in reference event 302A. When the second channel priority and the first channel priority are the same, UE 102 can implement the following reference... Figure 4 The technology discussed.

[0044] Events 312A, 314A, 315A (specifically, the "yes" branch of 315A) and 318A are collectively referred to in this disclosure as SDT selection procedure 320A. After determining that 318A uses SDT to transmit the second data, UE 102 may determine whether 322A uses CG-based SDT or RA-based SDT, as referenced Figure 3B-3D This will be discussed in more detail. Then, UE 102 can use either CG-based SDT or RA-based SDT to transmit the second data for 330A, depending on the result of determining 322A. Although UE 102 detects pending data for two channels in scenario 300A, in other implementations, UE 102 can detect pending data for more than two channels. In response, UE 102 can apply a technique similar to that described for scenario 300A. Specifically, to transmit pending data, UE 102 can select the procedure associated with the highest priority channel. For example, if three channels exist and the highest priority channel is associated with an SDT procedure, UE 102 can select the SDT procedure to transmit the pending data for that highest priority channel.

[0045] exist Figure 3AIn another embodiment not shown, UE 102 may compare the total amount of data to be processed with a threshold of SDT before comparing the priorities of the first channel and the second channel. For data to be transmitted via SDT, the data amount should be below the threshold, which may be pre-configured at UE 102 or configured at UE 102 by base station 104. In this embodiment, UE 102 compares the total amount of data to be processed (i.e., the first data and the second data) with the threshold before comparing the priorities of channel 315A. If the total amount is higher than the threshold, UE 102 may perform a conventional random access procedure 340A to transmit the data to be processed. If the total amount is lower than the threshold, UE 102 may compare the priorities of channel 315A and continue with the steps shown in scenario 300A. If UE 102 compares the priorities of channel 315A and determines that 318A uses SDT to transmit the second data, UE 102 may compare the amount of the second data with the threshold. If the amount of the second data is higher than the threshold, UE 102 may perform a conventional random access procedure 340A. If the amount of the second data is below the threshold, UE 102 uses CG-based or RA-based SDT to send the 330A second data.

[0046] Figure 3B Scenario 300B, similar to scenario 300A, is illustrated, where UE 102 determines 322B that CG-based SDT is used. Events 310B and 320B are similar to events 310A and 320A, respectively. After determining that 320B utilizes SDT to transmit second data, UE 102 determines 324B that UE 102 has been configured with a CG for a time period. UE 102 may receive the CG in a configuration message during the inactivity initiation process 310B. This time period may refer to the next frame, subframe, or time slot in which UE 102 can perform transmission, which may correspond to the remainder of the current frame or subframe or a subsequent frame or subframe. Therefore, UE 102 determines 324b that UE 102 has a CG at the time resource corresponding to the next transmission opportunity. Then, UE 102 determines 326B that the CG is used to transmit second data. Therefore, UE 102 transmits 330B the second data according to the CG. The message sent by UE 102 in 330B can be, for example, an RRC message, such as RRCResumeRequest or RRCSetupRequest.

[0047] Figure 3CScenario 300C, similar to scenario 300A, is illustrated, where UE 102 determines 322C that CG-based SDT is used. Events 310C and 320C are similar to events 310A and 320A, respectively. After determining that 320C utilizes SDT to transmit second data, UE 102 determines 325C that UE 102 has not yet configured a CG for a period of time (i.e., for time resources corresponding to the next transmission opportunity). However, UE 102 may be configured with a CG corresponding to time resources after that period. Therefore, in response to determining 325C, UE 102 may determine 327C that it will wait to transmit the second data until the UE has a later transmission opportunity with an available CG. For example, UE 102 may have a CG configured for a later period of time after that period. Then, UE 102 transmits the second data 330C according to the later available CG.

[0048] Alternatively, if UE 102 determines that UE 102 has not yet been configured for a period of time CG, then UE 102 can apply Figure 3D The technology is shown in the diagram. In scenario 300D, UE 102 determines that 322D uses RA-based SDT. Events 310D and 320D are similar to events 310A and 320A, respectively. Similar to scenario 300C, UE 102 determines that 325D UE 102 is not yet configured with a CG for a given time period. However, instead of performing a CG-based SDT, UE 102 determines that 328D uses RA-based SDT to transmit the second data. Then, UE 102 performs the 330D SDT random access procedure to transmit the second data.

[0049] In order to send the second data, UE 102 can utilize, for example... Figure 3D The diagram illustrates either a four-step or two-step random access procedure. UE 102 initiates the four-step random access procedure by sending a 332D random access preamble using the second type of random access resource discussed in reference event 302A above. Base station 104 responds by sending a 334D random access response (RAR) to UE 102. Upon receiving the RAR, UE 102 sends a 336D payload including second data to the base station. For example, the payload may include an RRCResumeRequest message or an RRCSetupRequest message. UE 102 may send the payload on the Physical Uplink Shared Channel (PUSCH). In response to receiving this payload, base station 104 sends a 338D contention resolution message to UE 102.

[0050] Events 332D, 334D, 336D, and 338D together constitute a four-step random access procedure, where the events can be "Msg1", "Msg2", "Msg3", and "Msg4" of the four-step random access procedure, respectively. Alternatively, UE 102 can perform a two-step random access procedure to send second data. UE 102 can send both the random access preamble and the payload in the "MsgA" of the two-step random access procedure. The random access preamble and the payload are two parts of MsgA sent at different times: UE 102 sends the random access preamble via the PRACH timing (e.g., similar to Msg1 in the four-step random access procedure), and UE 102 sends the payload via the PUSCH timing (e.g., similar to Msg3 in the four-step random access procedure). In response to MsgA, base station 104 sends "MsgB" to UE 102, including contention resolution and RAR.

[0051] Go to Figure 4 Scenario 400 is similar to Scenario 300A, but UE 102 determines that the first and second channels have the same priority. Specifically, events 410, 412, and 414 are similar to events 310A, 312A, and 314A, respectively. UE 102 determines 417 that the first channel priority is equal to the second channel priority. In response, UE 102 determines whether one or both of the channel configurations indicate that UE 102 will use SDT to transmit data on the associated channel. If so, UE 102 determines to use SDT to transmit data on the channel associated with the SDT. In Scenario 400, the second channel is associated with the SDT. Therefore, UE 102 determines to use SDT to transmit the second data. Similar to 322A, UE 102 determines 422 whether to use CG-based SDT or RA-based SDT (i.e., using the techniques described with reference to 322B-D), and based on the result of determining 422, transmits 430 the second data using either CG-based SDT or RA-based SDT. Later, UE 102 can use the conventional random access procedure to send the first data. If neither the first channel configuration nor the second channel configuration indicates that UE 102 will use SDT, then UE 102 performs the conventional random access procedure to send 440 data, similar to event 340A.

[0052] Similar to scenario 300A, although UE 102 detects pending data on two channels in scenario 400, in other implementations, UE 102 may detect pending data on more than two channels. In response, UE 102 may apply a technique similar to that described for scenario 400. Specifically, if UE 102 determines 419 that any channel on which UE 102 detects pending data is associated with a channel configuration instructing UE 102 to use SDT, then UE 102 may select SDT to transmit pending data on those channels associated with SDT. Otherwise, UE 102 may perform 440 a conventional random access procedure to transmit pending data.

[0053] Figure 5-7 This is a flowchart illustrating an example method that a UE can implement to perform the techniques disclosed herein.

[0054] Go to Figure 5 A UE (e.g., UE 102) can implement example method 500 to send a Media Access Control (MAC) control element (CE) to a base station (e.g., base station 104). At block 502, when the UE is operating in an inactive state, the UE detects the MAC CE for transmission to the base station. At block 504, the UE determines whether there is pending data in the UE's data buffer. If there is pending data in addition to the MAC CE, then at block 506, the UE can send the pending data and the MAC CE to the base station using a procedure based on channel determination corresponding to the data buffer. If there is pending data for more than one channel, the UE can apply... Figure 3A-4 The technology determines which procedure to use to send data and MAC CE. If there is no pending data in the data buffer, then in box 508, the UE uses the SDT procedure to send the MAC CE. UE 102 can use reference... Figure 3B-3D The discussed techniques determine whether to use a CG-based SDT or a RA-based SDT.

[0055] Go to Figure 6A UE (e.g., UE 102) can implement example method 600 to transition from an RA-based SDT to a conventional random access procedure. At block 602, when operating in an inactive state, the UE determines to perform a conventional random access procedure to transmit data (e.g., because the UE detects data for the first channel in its data buffer). At block 604, the UE determines that it is already performing or has determined to perform an RA-based SDT procedure. At block 606, the UE determines whether it has already transmitted a random access preamble for the RA-based SDT (i.e., using a second type of random access resource). If so, at block 608, the UE aborts the ongoing RA-based SDT procedure and instead initiates a conventional random access procedure (i.e., transmitting a preamble using a first type of random access resource). Otherwise, at block 610, the UE transmits a random access preamble corresponding to a conventional random access procedure, instead of a random access preamble corresponding to an RA-based SDT.

[0056] Reference Figure 7 A UE (e.g., UE 102) may implement example method 700 for communicating with a base station (e.g., base station 104) when the UE is operating in an inactive state (e.g., RRC_INACTIVE) associated with a protocol for controlling radio resources. In block 702, the UE operates in the inactive state and is configured to (i) transmit data on a first channel using a first procedure (e.g., a conventional random access procedure) that causes the UE to transition to a connected state associated with the protocol, and (ii) transmit data on a second channel using a second procedure that does not cause the UE to transition to a connected state. The first channel is associated with a first priority, and the second channel is associated with a second priority. For example, the UE may receive a first channel configuration for the first channel and a second channel configuration for the second channel (e.g., similar events within event 302A or procedures 310B-D, 410). Each channel configuration may indicate the priority of the channel and the procedure the UE should use to transmit data on the channel.

[0057] At block 704, the UE detects pending data addressed to the base station, including first data for a first channel and second data for a second channel (e.g., events 312A, 314A, 412, 414, or similar events within processes 320B-D, 420). For example, the UE may detect first data in a first data buffer associated with the first channel and second data in a second data buffer associated with the second channel. At block 706, the UE selects either a first or second process based on a comparison of the priority of the first channel with the priority of the second channel (e.g., events 315A, 419, or similar events within processes 320B-D). If the priority of the second channel is higher than the priority of the first channel, the UE selects the second process (e.g., events 315A-318A, 320B-D). If the priority of the first channel is higher than the priority of the second channel, the UE selects the first process (e.g., events 315A-340A). If the priority of the second channel is equal to the priority of the first channel, the UE selects the second process (e.g., events 417-422). At box 708, the UE uses the selected procedure (e.g., 330A-D, 340, 440) to send at least a portion of the data to be processed.

[0058] If the priority of the second channel is higher than that of the first channel, or if the channel priorities are equal, then UE 102 selects the second procedure and uses the second procedure to send the second data. UE 102 can later use the first procedure to send the first data. If the priority of the first channel is higher than that of the second channel, then UE 102 selects the first procedure and uses the first procedure to send two pending data, which may include both the first data and the second data.

[0059] The second procedure can be an SDT procedure. If the UE selects a second procedure, the UE can further select the type of the second procedure. Specifically, the UE can determine whether to use a configured grant procedure (e.g., CG-based SDT) or a random access procedure (e.g., RA-based SDT) based on whether the UE is configured with a CG for a time period corresponding to the next transmission opportunity (e.g., during the remainder of a frame or subframe, or during a subsequent frame or subframe). If the UE has a CG for that time period, the UE can use the CG to transmit the second data (e.g., event 330B). If the UE does not have a CG for that time period, in some implementations, the UE uses another CG to transmit the second data in a later time period after that time period (e.g., event 330C). In other implementations, the UE can use a random access resource dedicated to use in an inactive state (e.g., a second type of random access resource) to initiate a random access procedure and use the random access procedure to transmit the second data (e.g., event 330D).

[0060] The first procedure can be a traditional random access procedure. To send pending data, the UE can initiate a random access procedure using random access resources not dedicated to use in the inactive state (e.g., type 1 random access resources), and send pending data (e.g., events 340A, 440) during the random access procedure. In response to or during the random access procedure, the UE can transition to a connected state.

[0061] If the UE also detects a MAC CE addressed to the base station, the UE may send the MAC CE and at least a portion of the data to be processed in the selected process (e.g., box 506).

[0062] Furthermore, another aspect of this disclosure includes a method in a UE (e.g., UE 102) for communicating with a base station (e.g., base station 104) when the UE is operating in an inactive state associated with a protocol for controlling radio resources. The method includes detecting a Media Access Control (MAC) control element (CE) addressed to the base station (e.g., block 502). The method also includes determining that the UE does not have pending data addressed to the base station (e.g., block 504). Furthermore, the method includes, in response to this determination, sending a MAC CE to the base station without transitioning to a connection state associated with the protocol (e.g., block 508).

[0063] The following list of examples illustrates various embodiments explicitly contemplated in this disclosure:

[0064] Example 1. A method in a UE for communicating with a base station when the UE is operating in an inactive state associated with a protocol for controlling radio resources, the UE being configured to (i) transmit data on a first channel using a first procedure that causes the UE to transition to a connected state associated with the protocol, and (ii) transmit data on a second channel using a second procedure that does not cause the UE to transition to the connected state, the method comprising: detecting, by processing hardware of the UE, pending data addressed to the base station, the pending data including first data on the first channel and second data on the second channel; selecting, by the processing hardware, either the first procedure or the second procedure based on a comparison of the priority of the first channel and the priority of the second channel; and transmitting, by the processing hardware, at least a portion of the pending data using the selected procedure.

[0065] Example 2. According to the method of Example 1, the selection includes: selecting the second process if the priority of the second channel is higher than the priority of the first channel.

[0066] Example 3. According to the method described in Example 1, the selection includes: selecting the second process if the priority of the first channel is equal to the priority of the second channel.

[0067] Example 4. The method according to Example 2 or 3, wherein at least a portion of the data to be processed is the second data.

[0068] Example 5. The method according to any one of Examples 2-4, wherein the transmission includes: determining whether to use a configured authorization procedure or a random access procedure to transmit the at least portion of the data to be processed, based on whether the UE is configured with an authorization for a time period corresponding to the next transmission opportunity.

[0069] Example 6. According to the method in Example 5, the transmission includes: if the UE is configured with an authorization for the time period, then using the configured authorization to transmit the at least portion of the data to be processed.

[0070] Example 7. According to the method of Example 5, wherein the transmission includes: if the UE is not configured with an authorization for the time period, then in a later time period after the time period, using another configured authorization, to transmit the at least portion of the data to be processed.

[0071] Example 8. According to the method of Example 5, wherein the transmission includes: if the UE is not configured with authorization for the configuration of the time period, then: initiating the random access procedure using random access resources dedicated to use in the inactive state; and transmitting at least a portion of the data to be processed during the random access procedure.

[0072] Example 9. According to the method of Example 1, the selection includes: selecting the first process if the priority of the first channel is higher than the priority of the second channel.

[0073] Example 10. According to the method of Example 9, the transmission includes: initiating a random access procedure using random access resources not dedicated to use in the inactive state; and transmitting the data to be processed during the random access procedure.

[0074] Example 11. The method according to Example 10 further includes: in response to or during the random access procedure, the processing hardware switching to the connection state.

[0075] Example 12. The method according to any one of the foregoing examples, wherein the second process is a Small Data Transfer (SDT) process.

[0076] Example 13. The method according to any one of the foregoing examples, wherein detecting the data to be processed includes detecting the first data in a first data buffer associated with the first channel and detecting the second data in a second data buffer associated with the second channel.

[0077] Example 14. The method according to any one of the foregoing examples further includes: detecting a Media Access Control (MAC) control element (CE) addressed to the base station; and transmitting the MAC CE and at least a portion of the data to be processed using a selected procedure.

[0078] Example 15. The method according to any one of the foregoing examples further includes: receiving a configuration message from the base station by the processing hardware before detecting the data to be processed.

[0079] Example 16. According to the method of Example 15, the configuration message includes a first random access resource for the first process and a second random access resource for the second process, the second random access resource being dedicated to use in the inactive state.

[0080] Example 17. The method according to Example 15 or 16, wherein the configuration message includes the priority of the first channel and the priority of the second channel.

[0081] Example 18. The method according to any one of Examples 15-17, wherein the configuration message includes at least one configuration authorization.

[0082] Example 19. A user equipment (UE) includes processing hardware and is configured to implement the method according to any one of the foregoing examples.

[0083] The following additional considerations apply to the foregoing discussion.

[0084] User equipment implementing the technologies disclosed herein (e.g., UE 102) can be any suitable device capable of wireless communication, such as a smartphone, tablet computer, laptop computer, mobile game console, point-of-sale (POS) terminal, health monitoring device, drone, camera, media streaming dongle or other personal media device, wearable device (such as a smartwatch), wireless hotspot, femtocell, or broadband router. Furthermore, in some cases, the device user can be embedded in electronic systems such as a head unit of a vehicle or an advanced driver assistance system (ADAS). Additionally, the user equipment can operate as an Internet of Things (IoT) device or a mobile internet device (MID). Depending on the type, the user equipment may include one or more general-purpose processors, computer-readable storage, a user interface, one or more network interfaces, one or more sensors, etc.

[0085] Some embodiments described in this disclosure include logic or multiple components or modules. A module can be a software module (e.g., code stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit capable of performing certain operations and can be configured or arranged in a certain way. A hardware module may include dedicated circuitry or logic permanently configured to perform certain operations (e.g., as a dedicated processor, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC)). A hardware module may also include programmable logic or circuitry temporarily configured by software to perform certain operations (e.g., contained within a general-purpose processor or other programmable processor). The decision to implement a hardware module in dedicated and permanently configured circuitry or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

[0086] When implemented in software, these technologies can be provided as part of an operating system, a library used by multiple applications, or a specific software application. The software can be executed by one or more general-purpose processors or one or more dedicated processors.

Claims

1. A method for communicating with a base station in a user equipment (UE) when the UE is operating in an inactive state associated with a protocol for controlling radio resources, the method comprising: When the UE operates in an inactive state associated with a protocol for controlling radio resources, the UE detects pending data addressed to the base station, the pending data including (i) first data for a first channel, for which the UE is configured to use a random access (RA) procedure for restoring radio connectivity, the RA procedure causing the UE to transition to a connected state associated with the protocol, and (ii) second data for a second channel, for which the UE is configured to use a small data transfer (SDT) procedure to keep the UE in the inactive state; The UE selects either the RA procedure or the SDT procedure based on a comparison of the priority of the first channel and the priority of the second channel. as well as The UE uses a selected procedure to send at least a portion of the data to be processed.

2. The method of claim 1, wherein, The selection includes: If the priority of the second channel is higher than that of the first channel, then the SDT procedure is selected.

3. The method of claim 1 or 2, wherein, The selection includes: If the priority of the first channel is equal to the priority of the second channel, then the SDT procedure is selected.

4. The method according to claim 2, wherein, At least a portion of the data to be processed is the second data.

5. The method according to claim 2, wherein, Sending using the SDT procedure includes: Based on whether the UE is configured with an authorization for a time period corresponding to the next transmission opportunity, it is determined whether to use a configuration-based authorization CG procedure or an RA-based SDT procedure to send at least a portion of the data to be processed.

6. The method according to claim 5, wherein, The sending includes: If the UE is configured with an authorization for the configuration of the time period, then the authorization configured is used to send at least a portion of the data to be processed.

7. The method according to claim 5, wherein, The sending includes: If the UE is not configured with authorization for the time period, then at least a portion of the data to be processed is sent using authorization with another configuration in a later time period after the time period.

8. The method according to claim 5, wherein, The sending includes: If the UE is not configured with authorization for the configuration of the time period, then: The RA-based SDT procedure is initiated using random access resources dedicated to use during the inactive state; and At least a portion of the data to be processed is transmitted during the RA-based SDT process.

9. The method according to claim 1 or 2, wherein, The selection includes: If the priority of the first channel is higher than that of the second channel, then the RA procedure for restoring the radio connection is selected.

10. The method according to claim 9, wherein, The sending includes: The RA procedure for restoring radio connectivity is initiated using random access resources that are not specifically designed for use during the inactive state; and The data to be processed is transmitted during the RA process used to restore the radio connection.

11. The method according to claim 1, wherein, Detecting the data to be processed includes detecting the first data in a first data buffer associated with the first channel and detecting the second data in a second data buffer associated with the second channel.

12. The method according to claim 1, further comprising: Detect the Media Access Control (MAC) control element (CE) addressed to the base station; as well as Send the MAC CE and at least a portion of the data to be processed using the selected procedure.

13. The method according to claim 1, further comprising: Before detecting the data to be processed, the UE receives a configuration message from the base station.

14. The method according to claim 13, wherein, The configuration message includes the priority of the first channel and the priority of the second channel.

15. The method according to claim 13 or 14, wherein, The configuration message includes at least one authorized configuration.

16. A user equipment (UE) including processing hardware and configured to implement the method according to any one of the preceding claims.

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