Start of small data transmission

Abstract

An exemplary embodiment of the present disclosure relates to initiating a small data transmission (SDT). A first device determines whether an SDT is allowed to be initiated at a first protocol layer of the first device. According to the determination that the SDT is allowed to be initiated at the first protocol layer, the first device determines whether the SDT is allowed to be initiated at a second protocol layer of the first device. According to the determination that the SDT is allowed to be initiated at the second protocol layer, the first device initiates a communication procedure of the SDT with the second device via the first protocol layer. This solution can avoid not only erroneous resumption of radio bearers when the SDT procedure cannot be performed, but also unnecessary interactions between protocol layers.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and more specifically, to devices, methods, apparatuses, and computer-readable storage media for initiating small data transmission (SDT).

Background Art

[0002] In some communication systems, a communication device can transition between an inactive state and a connected state. In the inactive state, the communication device may not have established a connection with a communication network device. To avoid unnecessary signaling overhead and power consumption for establishing or re-establishing a connection, a communication device in the inactive state may perform a small data transmission (SDT) procedure with another communication device and does not need to establish a connection with the other communication device.

Summary of the Invention

[0003] Generally, exemplary embodiments of the present disclosure provide a solution for initiating SDT. If there are embodiments not included in the claims, they should be construed as useful examples for understanding the various embodiments of the present disclosure.

[0004] In a first aspect, a first device is provided. The first device comprises at least one processor and at least one memory including computer program code, and the at least one memory and the computer program code are configured to, using the at least one processor, determine whether small data transmission is permitted to be initiated at a first protocol layer of the first device, and, according to the determination that small data transmission is permitted to be initiated at the first protocol layer, determine whether small data transmission is permitted to be initiated at a second protocol layer of the first device, and, according to the determination that small data transmission is permitted to be initiated at the second protocol layer, initiate communication procedures for small data transmission with a second device via the first protocol layer.

[0005] In a second aspect, a method is provided. The method includes, at a first device, determining whether small data transmission is permitted to be initiated at a first protocol layer of the first device, and, according to the determination that small data transmission is permitted to be initiated at the first protocol layer, determining whether small data transmission is permitted to be initiated at a second protocol layer of the first device, and, according to the determination that small data transmission is permitted to be initiated at the second protocol layer, initiating communication procedures for small data transmission with a second device via the first protocol layer.

[0006] In a third aspect, a first device is provided. The first device includes means for determining whether small data transmission is permitted to be initiated at a first protocol layer of the first device, means for determining whether small data transmission is permitted to be initiated at a second protocol layer of the first device according to the determination that small data transmission is permitted to be initiated at the first protocol layer, and means for initiating a communication procedure for small data transmission with a second device via the first protocol layer according to the determination that small data transmission is permitted to be initiated at the second protocol layer.

[0007] In a fourth aspect, a computer-readable medium is provided. The computer-readable medium comprises program instructions for causing a device to execute a method according to at least the first aspect.

[0008] It should be understood that the Summary of the Invention section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will be readily understood through the following description.

[0009] Here, some exemplary embodiments will be described with reference to the accompanying drawings.

Brief Description of the Drawings

[0010]

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[0011] Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

[0012] Here, the principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and assist those skilled in the art in understanding and implementing the present disclosure, but do not imply any limitation regarding the scope of the present disclosure. The embodiments described herein can be implemented in various ways other than those described below.

[0013] In the following description and claims, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise defined.

[0014] References to "an embodiment", "embodiment", "exemplary embodiment", etc. in the present disclosure indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in relation to an embodiment, it is considered within the knowledge of those skilled in the art to use such feature, structure, or characteristic in relation to other embodiments, whether or not explicitly described.

[0015] In this specification, terms such as "first" and "second" may be used to describe various elements, but it should be understood that these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element. The term "and / or" as used in this specification encompasses any and all combinations consisting of one or more of the recited terms.

[0016] The terms used in this specification are for the sole purpose of describing particular embodiments and are not intended to limit the exemplary embodiments. The singular forms "a", "an", and "the" as used in this specification are intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms "comprises", "comprising", "has", "having", "includes", and / or "including", when used in this specification, specify the presence of the recited features, elements, and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0017] The term "circuit" as used in this application (a) a circuit implementation consisting only of hardware (such as an implementation consisting only of analog and / or digital circuits), and (b) a combination of a hardware circuit and software, for example (where applicable), (i) a combination of analog and / or digital hardware circuit(s) and software / firmware, and (ii) any part of a hardware processor(s) and software (including a digital signal processor(s), software, and memory(ies) that cooperate to cause a device such as a mobile phone or a server to perform various functions). (c) A hardware circuit(s) and / or a processor(s) such as a microprocessor(s) or a part of a microprocessor(s), which requires software (e.g., firmware) for operation but may not have software if it is not necessary for operation. can refer to one or more or all of the following.

[0018] This definition of circuit applies to all uses of this term in this application including any claims. As a further example, the term circuit as used in this application includes embodiments of just a hardware circuit or a processor (or processors), or embodiments of a hardware circuit or a part of a processor, along with the software and / or firmware associated therewith (or therewith). The term circuit also includes, for example, a baseband integrated circuit or a processor integrated circuit of a mobile device, or a similar integrated circuit of a server, a cellular network device, or other computing or network device, when applicable to the components of a particular claim.

[0019] As used herein, the term "communication network" refers to a network compliant with any suitable communication standard, such as New Radio (NR), Long-Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), and NarrowBand Internet of Things (NB-IoT). Further, the communication between a terminal device and a network device in a communication network can be carried out according to any suitable generation of communication protocols, including but not limited to the communication protocols of the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), and / or any other protocol known currently or developed in the future. Embodiments of the present disclosure can be applied to various communication systems. Considering the rapid development in communication, it is natural that there will also be future communication technologies and systems capable of implementing the present disclosure. The scope of the present disclosure should not be regarded as limited only to the aforementioned systems.

[0020] As used herein, the term "network device" refers to a node within a communication network, and a terminal device accesses the network through the node and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) depending on the terms and technologies applied, for example, Node B (NodeB or NB), evolved Node B (eNodeB or eNB), NR NB (also referred to as gNB), remote radio unit (RRU), radio header (RH), remote radio head (RRH), relay, integrated access backhaul (IAB) node, low-power nodes such as femto, pico, etc., as well as satellite network devices, non-terrestrial network (NTN) devices or non-ground network devices such as low-earth orbit (LEO) satellites and geostationary earth orbit (GEO) satellites, aircraft network devices, and the like. In some exemplary embodiments, a radio access network (RAN) split architecture includes a central unit (CU) and a distributed unit (DU) in an IAB donor node. The IAB node includes a mobile terminal (IAB-MT) portion that operates like a UE with respect to the parent node, and the DU portion of the IAB node operates like a base station with respect to the next-hop IAB node.

[0021] The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a mobile subscriber station, a mobile station (MS), or an access terminal (AT). Terminal devices can include, but are not limited to, mobile phones, cellular phones, smartphones, voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, game terminal devices, music storage and playback appliances, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer premise equipment (CPE), Internet of Things (IoT) devices, wristwatches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial processing chain and / or an automated processing chain), household electronics, and devices operating in commercial and / or industrial wireless networks. A terminal device may also correspond to the mobile termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably.

[0022] As used herein, the terms "resource", "transmission resource", "resource block", "physical resource block" (PRB), "uplink resource", or "downlink resource" may refer to any resource for performing communications, such as communications between a terminal device and a network device, including resources in the time domain, resources in the frequency domain, resources in the spatial domain, resources in the code domain, or other resources enabling communications. In the following, resources in both the frequency domain and the time domain are used as examples of transmission resources to describe some exemplary embodiments of the present disclosure. It should be noted that the exemplary embodiments of the present disclosure are equally applicable to other resources in other domains.

[0023] FIG. 1 shows an exemplary communication environment 100 in which exemplary embodiments of the present disclosure may be implemented. In the communication environment 100, a plurality of communication devices including a first device 110 and a second device 120 may communicate with each other.

[0024] In the example of FIG. 1, the first device 110 is shown as a terminal device, and the second device 120 is shown as a network device that provides services to the terminal device. The serving area of the second device 120 may be referred to as cell 102.

[0025] It should be understood that the devices and their connections shown in FIG. 1 are for illustrative purposes only and do not imply any limitations. The environment 100 may include any suitable number of devices adapted to implement the embodiments of the present disclosure. Although not shown, one or more additional devices may be placed within the cell 102, and one or more additional cells may be deployed within the environment 100. It should be noted that the second device 120 is shown as a network device, but it may be a device other than a network device. The first device 110 is shown as a terminal device, but it may be a device other than a terminal device.

[0026] In some exemplary embodiments, when the first device 110 is a terminal device and the second device 120 is a network device, the link from the second device 120 to the first device 110 is referred to as a downlink (DL), while the link from the first device 110 to the second device 120 is referred to as an uplink (UL). In the DL, the second device 120 is a transmitting (TX) device (i.e., a transmitter), and the first device 110 is a receiving (RX) device (i.e., a receiver). In the UL, the first device 110 is a TX device (i.e., a transmitter), and the second device 120 is an RX device (i.e., a receiver).

[0027] Communication in the communication environment 100 may be carried out according to any suitable communication protocol(s), and any suitable communication protocol(s) include, but are not limited to, cellular communication protocols such as the first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol known currently or developed in the future. Further, the communication may utilize any suitable wireless communication technology, which includes, but is not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexing (FDD), time division duplexing (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology known currently or developed in the future.

[0028] The first device 110 and the second device 120 may include a protocol stack having a plurality of protocol layers. FIG. 2 shows an exemplary protocol stack of the first device 110. As shown, the protocol stack of the first device 110 may include a Radio Resource Control (RRC) layer 202, a Packet Data Convergence Protocol (PDCP) layer 204, and a Medium Access Control (MAC) layer 206. To facilitate communication between the first device 110 and other devices, each of the protocol layers may perform corresponding services and functions. Although not shown, the protocol stack of the first device 110 may include additional protocol layers in addition to the RRC layer, PDCP layer, and MAC layer. Other protocol layers may include a Non-Access Stratum (NAS) above the RRC layer, a Radio Link Control (RLC) layer between the RRC layer and the MAC layer, and a Physical (PHY) layer.

[0029] Although not shown, the second device 120 may include a protocol stack similar to that of the first device 110. Communication between devices such as between the first device 110 and the second device 120 is typically performed within the same protocol layer between the two devices. For example, communication from the RRC layer 202 of the first device 110 is transmitted through the PDCP layer 204, the MAC layer 206, and is sent to the second device 120 via the PHY layer. When the communication is received at the second device 120, it is transmitted through the protocol layers of the second device 120 in reverse order.

[0030] During operation, a device (e.g., a terminal device) can transition between an inactive state and a connected state. The inactive state may sometimes be referred to as an inactive mode, an RRC_INACTIVE state / mode, and such terms are used interchangeably herein. The connected state may sometimes be referred to as a connected mode, an active state / mode, or an RRC_CONNECTED state / mode, and such terms are used interchangeably herein.

[0031] Typically, to transition a terminal device from an inactive state to a connected state by establishing or re - establishing a connection between the terminal device and a network device, a certain amount of signaling overhead and power consumption occur. For at least one data transmission of an inactive terminal device, if connection setup and subsequent connection release occur, even if the data packets are very small and infrequent, unnecessary power consumption and signaling overhead can occur. Currently, an inactive terminal device may be able to perform small data transmission (SDT). As used herein, the term "SDT" refers to a type of transmission in which a small amount of data is transmitted, although other terms may also be used.

[0032] There are various applications that involve the exchange of relatively small amounts of data. For example, in some applications of mobile devices, SDT can include traffic from instant messaging (IM) services, heart - beat traffic or keep - alive traffic from IM or email clients and other services, push notifications from various applications, and / or traffic from wearable devices (e.g., including periodic positioning information). In some applications of non - mobile devices, SDT can include sensor data (e.g., temperature measurements, pressure measurements transmitted periodically or in an event - triggered manner in an IoT network), metering information and warning information sent from smart meters, and / or the like.

[0033] The signaling overhead and latency that occur in inactive devices for small data packets are an overall problem that affects not only the network performance and efficiency but also the battery performance. Usually, any device having intermittent small data packets in the inactive state benefits from enabling SDT. Desirably, the device should apply some criteria for selecting SDT or non-SDT. These criteria may be related to data availability, resource availability, channel quality, and SDT mode-specific checks, etc. However, currently, there is no solution that specifically defines how the selection between SDT and non-SDT is made at different protocol layers of the device.

[0034] According to some exemplary embodiments of the present disclosure, a solution for initiating the SDT procedure is provided. In this solution, the permission for SDT initiation is checked at different protocol layers. When it is found that the initiation of SDT is permitted, the communication procedure of SDT is initiated. With this solution, before the protocol layer determines the initiation of SDT, the permission of SDT is further checked at other layers.

[0035] By splitting the SDT initiation criteria among different protocol layers, each of the protocol layers can focus on its respective related services and functions regarding SDT. Also, various combinations of SDT initiation criteria are possible among the protocol layers. Further, considering that in a situation where the SDT procedure can be initiated, some radio bearers permitted for SDT can be resumed, it is beneficial to define an optimal criteria check split among the protocol layers. Thus, it is possible not only to avoid an incorrect resume of radio bearers when the SDT procedure cannot be executed but also to avoid unnecessary interactions among the protocol layers.

[0036] Exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0037] Referring now to FIG. 3, which shows a signaling flow 300 for SDT start according to some exemplary embodiments of the present disclosure. The signaling flow 300 may include operations and interactions between different protocol layers of the first device 110. For the sake of discussion, reference is made to the communication environment shown in FIG. 1 and the protocol stack shown in FIG. 2.

[0038] During operation, for example, when there is data to be transmitted to the second device 120, the first device 110 executes corresponding processing at each protocol layer of the protocol stack. For example, if data arrives (301) at the PDCP layer 204 of the first device 110, other protocol layers including the RRC layer 202 and the MAC layer 206 may operate to initiate a communication procedure with the second device 120. The first device 110 may also determine whether to initiate an SDT or non-SDT communication procedure within its own protocol stack. In some exemplary embodiments, the first device 110 may be in an inactive state or in another operating state where SDT can be selected for communication.

[0039] Specifically, the first device 110 determines (302) at a first protocol layer, for example, the RRC layer 202 which is a higher layer, whether the start of SDT is permitted (or available). The start of SDT is triggered at the first device 110 when some predetermined criteria are met. According to embodiments of the present disclosure, the criteria are divided among the protocol layers of the first device 110, and one or more criteria are checked at the RRC layer 202. Exemplary criteria at the RRC layer 202 are discussed in detail below.

[0040] When it is determined that the start of SDT is permitted (or available) in the RRC layer 202, for example, when it is determined that the criteria set in the RRC layer 202 are met, instead of directly resuming the radio bearer configured for SDT, the first device 110 determines (304) in a second protocol layer, for example, the lower layer MAC layer 206, whether the start of SDT is permitted. According to an embodiment of the present disclosure, one or more criteria are checked in the MAC layer 206 to determine whether the start of SDT is permitted.

[0041] In some exemplary embodiments, when it is determined that the start of SDT is permitted in the RRC layer 202, the RRC layer 202 may send a request to the MAC layer 206 to determine whether SDT is permitted (303). In response to the request from the RRC layer 202, the MAC layer 206 may operate to determine whether one or more criteria for permission to start SDT are met.

[0042] When it is determined that the start of SDT is permitted or available in the MAC layer 206, for example, when it is determined that the criteria set in the MAC layer 206 are met, the RRC layer 202 may start a communication procedure for SDT (also referred to as an SDT procedure) with the second device 120 (306A). In some exemplary embodiments, when it is determined that the start of SDT is permitted in the MAC layer 206, the MAC layer 206 may send an indication of permission or availability to start SDT to the RRC layer 202 (305A). In response to this indication, the RRC layer 202 may operate to start a communication procedure for SDT with the second device 120.

[0043] In some exemplary embodiments, since the MAC layer 206 also confirms that SDT is permitted, the RRC layer 202 may determine to execute an SDT RRC resume with an SDT radio bearer to initiate the communication procedure of SDT (306A). The radio bearers to be resumed for SDT may include a signaling radio bearer (SRB) for SDT, such as SRB1 or SRB2, and a data radio bearer (DRB). In an exemplary embodiment, the RRC layer 202 may resume SRB1 or SRB2 for SDT. In an exemplary embodiment, the RRC layer 202 may send a request to resume at least one radio bearer (e.g., SRB or DRB) for SDT to the PDCP layer 204 (307). In some exemplary embodiments, after resuming the radio bearer, the PDCP layer 204 may input data for transmission to a lower layer such as the RLC layer (309), which is further processed by the MAC layer 206. In some exemplary embodiments, to initiate the communication procedure of SDT, the RRC layer 202 may further send a common control channel (CCCH) RRC resume request for SDT to the MAC layer 206 (308A). Through the above processing, the communication procedure of SDT may be initiated at the first device 110, and data may be transmitted to the second device 120 using the communication procedure of SDT.

[0044] In a conventional protocol stack, when the RRC layer of a device determines that it can initiate SDT communication with another device, the RRC layer may directly resume radio bearers such as DRBs and / or SRBs. If it is found at the MAC layer that SDT is not available, such as when resources for SDT are invalid, complex problems may occur in the protocol stack due to the erroneously resumed radio bearers. According to an exemplary embodiment of the present disclosure, by checking the permission for SDT start in both the RRC layer and the MAC layer, it is possible to avoid erroneously resuming radio bearers when it is found that SDT is not available at the MAC layer, and if a radio bearer is erroneously resumed, unnecessary interactions may have occurred between protocol layers.

[0045] Some detailed examples regarding the permission criteria for starting SDT, which is split between the RRC layer 202 and the MAC layer 206, are discussed below. To better understand the criteria being discussed, some exemplary SDT modes are first introduced.

[0046] In some exemplary embodiments, SDT can be executed based on a random access (RA) procedure or by using a configured grant (CG). Thus, based on the resource type used for the SDT procedure (e.g., RA resource or CG resource), two or more different SDT modes can be defined. In some examples, the SDT mode based on the RA procedure can be referred to as the RA-based SDT mode or RA-SDT mode. The SDT mode that uses CG for data communication can be referred to as the CG-based SDT mode or CG-SDT mode. In the RA-based SDT mode, data can be transmitted from the first device 110 to the second device 120 in MsgA of the two-step RA procedure or in Msg3 of the four-step RA procedure. In the CG-based SDT mode, data transmission(s) can be directly executed using the resources of the CG, such as the resources of configured grant type 1.

[0047] In some exemplary embodiments, since the RA procedure can include a two-step RA procedure or a four-step RA procedure, different RA-based SDT modes can exist, namely the SDT mode using the two-step RA procedure and the SDT mode using the four-step RA procedure. The RA-based SDT mode based on the two-step RA resource can be referred to as the two-step RA-based SDT mode, and the RA-based SDT mode based on the four-step RA resource can be referred to as the four-step RA-based SDT mode. According to the two-step RA-based SDT mode, data can be transmitted from the first device 110 to the second device 120 in MsgA of the two-step RA procedure started with the second device 120. According to the four-step RA-based SDT mode, data can be transmitted in Msg3 of the four-step RA procedure started with the second device 120.

[0048] In some exemplary embodiments of the present disclosure, several SDT modes are described, but it will be understood that other applicable SDT modes may exist. In some exemplary embodiments, a plurality of different SDT modes may be defined based on the specific number or range of numbers of continuous data transmissions permitted in the SDT procedure. For example, an SDT mode may be defined as permitting only one data transmission during the SDT procedure, and another SDT mode may be defined as permitting two or more data transmissions during the SDT procedure, among other things.

[0049] To determine (302) whether SDT is permitted in the RRC layer 202, radio bearer data availability-based criteria may be applied to SDT in the RRC layer 202. In some exemplary embodiments, the RRC layer 202 may determine whether there is one or more radio bearers for which SDT is permitted and whether data is available on at least one radio bearer for which SDT is permitted. In some cases, not all radio bearers are configured for SDT. If the RRC layer 202 determines that there is no data available on the SDT radio bearer(s), the RRC layer 202 may determine that SDT is not permitted. If it determines that such data exists, the RRC layer 202 may determine that the radio bearer data availability-based criteria are met.

[0050] In some exemplary embodiments, alternatively or additionally, the RRC layer 202 may further determine whether one or more threshold-based criteria for SDT are met. The threshold-based criteria may include criteria based on a data volume threshold set for SDT. The RRC layer 202 may determine whether the amount of data to be transmitted meets the requirements based on the data volume threshold set for SDT. In some exemplary embodiments, the requirements may not be specific to the SDT mode but may be common to SDT, and the data volume threshold for SDT may be set in the RRC layer 202. If the amount of data to be transmitted is less than or (alternatively) strictly below the data volume threshold, the requirements for SDT may be defined as being met. In this case, the RRC layer 202 may determine whether the start of SDT is permitted by comparing the amount of data with the data volume threshold.

[0051] In some exemplary embodiments, the first device 110 may be configured in one or more SDT modes, and one or more data volume thresholds specific to the one or more SDT modes may be set in the RRC layer 202. When the data volume threshold specific to this SDT mode is met, the requirements for starting the SDT mode may be met. For example, a first data volume threshold may be set for the first SDT mode, and a second data volume threshold may be set for the second SDT mode. The first data volume threshold may be lower than the second data volume threshold. If the first device 110 determines that the amount of data to be transmitted is less than or equal to the first data volume threshold of the first SDT mode, the first SDT mode may be selected to start. In some exemplary embodiments, if the first device 110 determines that the amount of data to be transmitted exceeds the first data volume threshold and is less than or equal to the second data volume threshold of the second SDT mode, the first device 110 may select the second SDT mode.

[0052] In some exemplary embodiments, in addition to, or as an alternative to, data volume threshold-based criteria, the threshold-based criteria may include criteria based on a channel quality threshold set for SDT. The channel quality between the first device 110 and the second device 120 may be compared with the channel quality threshold to determine whether SDT is permitted. In some exemplary embodiments, the criteria may be based on one or more of received signal power (RSRP), received signal quality (RSRQ), and / or other elements reflecting the channel quality between the first device 110 and the second device 120, such as signal-to-interference-plus-noise ratio (SINR) or path loss, etc., and the channel quality may be measured. The RRC layer 202 may determine whether the channel quality meets the requirements based on the channel quality threshold set for SDT. In some exemplary embodiments, the requirements may not be specific to the SDT mode but may be common to SDT, and the channel quality threshold for SDT may be set in the RRC layer 202. When the channel quality exceeds the channel quality threshold, the requirements for SDT may be defined as being met. In this case, the RRC layer 202 may determine whether the start of SDT is permitted by comparing the channel quality with the channel quality threshold. In some exemplary embodiments, similar to the data volume threshold-based criteria, one or more channel quality thresholds specific to one or more SDT modes may be set in the RRC layer 202. By comparing the channel quality with the SDT mode-specific threshold, the RRC layer 202 may determine the SDT mode(s) for which the start may be permitted.

[0053] In some exemplary embodiments, alternatively or additionally, the RRC layer 202 may further apply some resource availability-based criteria for SDT. The RRC layer 202 may determine whether there are resources configured for SDT. For example, the RRC layer 202 may determine whether there is a CG configured for SDT and / or whether there is a RA resource configured for SDT. If the first device 110 is composed of a CG and / or a RA resource for SDT, it is determined in the RRC layer 202 that the start of SDT is permitted.

[0054] In some exemplary embodiments, the RRC layer 202 may not need to determine the validity of the resources configured for SDT. The verification of the resources configured for SDT may be performed by the MAC layer 206. As shown above, after the MAC layer 206 also confirms that SDT is permitted, the communication procedure of SDT is started by the RRC layer 202. Therefore, when there are no valid resources, it is possible to prevent the RRC layer 202 from starting the communication procedure.

[0055] In some exemplary embodiments, since the RRC layer 202 may not be configured to determine which type of RA procedure should be started for communication with the second device 120, or to determine whether an RA procedure or a CG-based procedure should be started, the criteria applied in the RRC layer 202 may not be specific to the SDT mode, but are general to all possible SDT modes.

[0056] In some exemplary embodiments, after applying the criteria of RRC layer 202, RRC layer 202 may be able to determine which one or more SDT modes may be permitted. For example, RRC layer 202 may be composed of one or more data volume-based criteria or channel quality-based criteria that are specific to one or more SDT modes, such as a CG-based SDT mode, an RA-based SDT mode, a two-step-based SDT mode, or a four-step-based SDT mode. In this case, when any of the criteria are met, RRC layer 202 may determine that the start of the corresponding SDT mode(s) is permitted.

[0057] In some exemplary embodiments, RRC layer 202 may perform checks based on criteria that do not depend on the selection of the SDT mode or the selection of the UL carrier (e.g., a normal UL carrier or a supplementary UL (SUL) carrier).

[0058] The various criteria in RRC layer 202 have been discussed above. It will be understood that RRC layer 202 may apply one or more of the above criteria and / or other possible criteria to determine the permission of SDT. In this regard, the scope of the present disclosure is not limited.

[0059] As described above, when RRC layer 202 determines that the start of SDT is permitted based on the criteria of RRC layer 202, RRC layer 202 may not directly start the communication procedure of SDT to communicate data. Instead, before starting the communication procedure, RRC layer 202 may send a request to MAC layer 206 (303) to further determine whether SDT may be permitted and when SDT may be permitted. In some exemplary embodiments, when RRC layer 202 can determine that the start of one or more target SDT modes is permitted, RRC layer 202 may send a request to MAC layer 206 (303) to determine whether the start of one or more target SDT modes is permitted in the second protocol layer.

[0060] In the MAC layer 206, when receiving a request to determine the permission of one or more specific target SDT modes, the criteria of the MAC layer 206 regarding these SDT modes are applied, and based on the criteria of the MAC layer 206, it can be determined whether any of them are permitted. In other cases, the MAC layer 206 receives a general request from the RRC layer 202 and determines whether it can start any SDT mode. The MAC layer 206 can apply the criteria of the MAC layer 206 to check the permission of SDT or the permission of all possible SDT modes configured for the first device 110.

[0061] To determine (304) whether SDT is permitted in the RRC layer 202, radio bearer data availability-based criteria can be applied to SDT. In some exemplary embodiments, if there are no various modes specified for SDT, the RRC layer 202 can determine whether the start of SDT is permitted. In some exemplary embodiments, the MAC layer 206 can determine the permission of start regarding one or more SDT modes configured for the first device 110. As described above, in some exemplary embodiments, the SDT mode can be indicated by the RRC layer 202.

[0062] In some exemplary embodiments, the first device 110 can be composed of a plurality of UL carriers (such as normal UL carriers or SUL carriers, etc.) for communicating with the second device 120. In such a case, the MAC layer 206 can select one of the UL carriers for communication. In some exemplary embodiments, the selection of the UL carrier can follow a legacy selection mechanism that is independent of SDT. In an exemplary embodiment, the selection of the UL carrier can be performed based on a channel quality threshold that is not specifically set for SDT or any SDT mode.

[0063] In some exemplary embodiments, a channel quality threshold can be set for SDT, and MAC layer 206 is provided inIt can be determined, which may be different from the threshold used in the legacy selection mechanism. The MAC layer 206 can determine whether the channel quality over a given UL carrier meets the requirements based on the channel quality threshold set for SDT in order to select a UL carrier. In some examples, the requirements can be met when the channel quality over a given UL carrier exceeds a specific channel quality threshold. In this case, the MAC layer 206 can select a given UL carrier.

[0064] Once a UL carrier is selected, the MAC layer 206 can apply further criteria (if any) to determine whether the start of SDT on the selected UL carrier is permitted. In some exemplary embodiments, the MAC layer 206 can apply SDT resource availability-based criteria. The MAC layer 206 can determine whether resources are configured and valid for SDT, or whether resources are configured and valid for a specific SDT mode.

[0065] For example, when a CG for performing SDT is configured for the first device 110, the MAC layer 206 can determine whether the CG is valid by determining whether the timing advance (TA) of the first device 110 is valid. If the TA is valid, the CG is determined to be valid. In some exemplary embodiments, a new TA timer for TA maintenance can be set for CG-based SDT. In some exemplary embodiments, additionally or alternatively, the validity of the CG for SDT can be based on other factors including whether one or more beams are valid for the CG, whether the CG is associated with the selected synchronization signal block (SSB), and whether the channel quality (e.g., RSRP) has changed beyond the corresponding channel quality threshold. In this regard, the scope of the present disclosure is not limited.

[0066] In some exemplary embodiments, when the RA resource is configured for the first device 110, the MAC layer 206 may further determine whether the RA resource is valid for SDT. In some exemplary embodiments, the MAC layer 206 may determine that a two-step RA resource or a four-step RA resource is available and valid for SDT. The RA resource may include, for example, a physical random access channel (PRACH) and a preamble, as well as dedicated radio resources for the RA procedure of SDT with high probability.

[0067] In some exemplary embodiments, by checking the validity of the CG and / or RA resource, the MAC layer 206 may be able to determine whether the start of the CG-based SDT mode or the RA-based SDT mode (e.g., the two-step RA-based SDT mode or the four-step RA-based SDT mode) is permitted.

[0068] In some exemplary embodiments, alternatively or additionally, the MAC layer 206 may further determine whether one or more threshold-based criteria for SDT are met. The threshold-based criteria may include criteria based on a data volume threshold set for SDT, and criteria based on a channel quality threshold set for SDT. In some exemplary embodiments, when the MAC layer 206 is configured with threshold-based criteria, it may not be necessary for the RRC layer 202 to perform a threshold-based criteria check for SDT. In some exemplary embodiments, both the RRC layer 202 and the MAC layer 206 may perform a threshold-based criteria check for SDT, but different thresholds may be set for the two layers.

[0069] In some exemplary embodiments, similar to the criteria described above for the RRC layer 202, the criteria based on the data volume threshold may include requirements based on the data volume threshold set for SDT, or may include requirements based on one or more data volume thresholds specifically set for one or more SDT modes. In some exemplary embodiments, the criteria based on the channel quality threshold may include requirements based on the channel quality threshold set for SDT, or may include requirements based on one or more channel quality thresholds specifically set for one or more SDT modes. The amount of data transmitted together with the corresponding data volume threshold(s) and by compare with which, and / or the corresponding channel quality threshold(s) and channel quality compare with each other by which, the MAC layer 206 may determine whether SDT is permitted, or may determine which SDT mode is permitted. In some exemplary embodiments, SDT is permitted when both the criteria based on the data volume threshold and the channel quality threshold are satisfied.

[0070] The various criteria in the MAC layer 206 have been discussed above. It will be understood that the MAC layer 206 may apply one or more of the above criteria and / or other possible criteria to determine the permission of SDT. In this regard, the scope of the present disclosure is not limited. As described above, when it is determined that the start of SDT is permitted in the MAC layer 206, the MAC layer 206 may send an indication of the permission or availability of SDT start to the RRC layer 202 (305A). In some exemplary embodiments, when the MAC layer 206 determines that a specific SDT mode is permitted, the MAC layer 206 may send an indication of the permitted SDT mode to the RRC layer 202 (305A). In response to the indication from the MAC layer 206, the RRC layer 202 may operate to start the communication procedure of SDT with the second device 120. When a specific SDT mode is indicated, the RRC layer 202 may start the communication procedure according to the SDT mode.

[0071] In the above embodiment, the operation of the protocol layer when it is determined that SDT is permitted has been described. In some cases, when it is found that SDT is rejected at the RRC layer 202 or the MAC layer 206, for example, when one or more of the criteria in the RRC layer 202 or the MAC layer 206 are not satisfied, the first device 110 may initiate a non-SDT communication procedure with the second device 120. Continuing to refer to FIG. 2. For example, if the RRC layer 202 determines that SDT is rejected because there are no resources or radio bearers configured for SDT or for which SDT is permitted, the RRC layer 202 may initiate a non-SDT communication procedure (also referred to as a non-SDT procedure) with the second device 120 (306B). For example, the RRC layer 202 may decide to resume SBR, such as S BR 1. The RRC layer 202 may further send a CCCH RRC resume request for non-SDT to the MAC layer 206 (308B). The PDCP layer 204 and the MAC layer 206 may operate appropriately to execute the non-SDT communication procedure. Using the non-SDT procedure, data may be sent to the second device 120.

[0072] If the RRC layer 202 determines that SDT is permitted, but the MAC layer 206 determines that the start of SDT is not permitted, the MAC layer 206 may send an indication of rejection or unavailability of SDT start to the RRC layer 202 (305B). Upon receiving such an indication from the MAC layer 206, the RRC layer 202 may accordingly initiate a non-SDT communication procedure (306B).

[0073] The interaction between protocol layers has been discussed above. Exemplary procedures executed at the MAC layer 206 according to some exemplary embodiments may be summarized as follows. The corresponding steps of the signaling flow 300 are shown below. - When the MAC receives a start request for the SDT procedure (step 303), it performs SUL / UL selection (step 304) based on the SUL / UL_SDT_RSRP threshold (which may be the same as or different from the conventional SUL / UL RSRP threshold). - After the selection of the UL carrier (step 304), - The MAC performs CG verification (including TA, beam, RSRP criteria, etc.) for the selected UL carrier (step 304), - If there is a valid CG for the SDT, - The MAC indicates to the RRC that it can start (CG-)SDT and executes CG-SDT (step 305A), - If there is no valid CG (not configured or not meeting any criteria), - The MAC checks the availability of 2-step and 4-step RA-SDT, and performs 2-step / 4-step RA selection (step 304) based on the 2-step / 4-step RA SDT-RSRP threshold (which may be the same as or different from the conventional 2-step / 4-step selection RSRP threshold), - If there is a valid RA resource for the SDT for the selected RA type, - The MAC indicates to the RRC that it can start (RA-)SDT and thus executes RA-SDT (step 305A), - If there is no valid CG for the SDT and no valid 2-step or 4-step RA resource for the SDT on the selected UL (note that the first device 110 may be configured with only CG-SDT resources without RA-SDT or with only 2-step RA or 4-step RA configured for SDT) (step 304), - The MAC indicates to the RRC that it cannot execute the SDT procedure (step 305B).

[0074] Exemplary procedures performed at the RRC layer 202 according to some exemplary embodiments may be summarized as follows. The corresponding steps of the signaling flow 300 are shown below. - The SDT criteria are For example, whether the SDT is configured for the related DRB and whether the UL payload conforms to the SDT threshold, etc. case , and the SDT-RSRP criteria are met whether or not (Step 302), - Request the MAC to perform SDT resource verification (Step 303), - When receiving an SDT available indication from the MAC (Step 305A), - Resume SRB1 / (SRB2) / SDT DRB(s) (Steps 307 and 308A), - Perform SDT resume and send the SDT resume to the MAC (Steps 306A and 309), - When receiving an unavailable indication from the MAC (Step 305B), - Resume SRB1, - Perform non-SDT resume (Steps 306B and 308B).

[0075] FIG. 4 shows a flowchart of an exemplary method 400 implemented at a first device 110 according to some exemplary embodiments of the present disclosure. For discussion purposes, method 400 is described from the perspective of the first device 110 with respect to FIG. 1.

[0076] At block 410, the first device 110 determines whether the start of SDT is permitted in the first protocol layer (e.g., RRC layer 202) of the first device 110. If the start of SDT is permitted in the first protocol layer, at block 420, the first device 110 determines whether the start of SDT is permitted in the second protocol layer (e.g., MAC layer 206) of the first device 110. If the start of SDT is permitted in the second protocol layer, at block 430, the first device 110 starts the SDT communication procedure with the second device 120 via the first protocol layer.

[0077] In some exemplary embodiments, if the start of SDT is rejected in the first protocol layer or the second protocol layer, at block 440, the first device 110 may start further non-SDT communication procedures with the second device 120 via the first protocol layer.

[0078] In some exemplary embodiments, the first device 110 may determine that the start of SDT is permitted in the first protocol layer by determining that at least one of the following criteria is met: resources for SDT are configured, resources for at least one SDT mode are configured, data is available on at least one radio bearer for which SDT is permitted, or the amount of data to be transmitted meets the requirements based on a first data amount threshold set for SDT.

[0079] In some exemplary embodiments, at least one SDT mode includes at least one of the following: a first SDT mode based on a configured grant, a second SDT mode based on a random access procedure, a third SDT mode based on a two-step random access procedure, and a fourth SDT mode based on a four-step random access procedure.

[0080] In some exemplary embodiments, if the start of SDT is permitted at the first protocol layer, the first device 110 may cause one of the following requests, a first request to determine whether the start of SDT is permitted at the second protocol layer, or a second request to determine whether the start of the target SDT mode is permitted at the second protocol layer, to be transmitted from the first protocol layer to the second protocol layer.

[0081] In some exemplary embodiments, the first device 110 may determine whether the start of SDT is permitted at the second protocol layer by determining whether the start of SDT is permitted at the second protocol layer in response to the first request or by determining whether the start of the target SDT mode is permitted at the second protocol layer in response to the second request.

[0082] In some exemplary embodiments, the first device 110 may determine whether the start of SDT is permitted at the second protocol layer by determining whether the start of at least one SDT mode is permitted at the second protocol layer.

[0083] In some exemplary embodiments, if the start of one of at least one SDT mode is permitted at the second protocol layer, the first device 110 may cause an indication of the determined SDT mode to be transmitted from the second protocol layer to the first protocol. The first device 110 may start the communication procedure of SDT by starting the communication procedure according to the determined SDT mode via the first protocol layer in response to the indication of the determined SDT mode.

[0084] In some exemplary embodiments, the first device 110 may determine that the start of SDT is permitted in the second protocol layer by determining that at least one of the following criteria is met: resources configured for SDT are valid, resources configured for at least one SDT mode are valid, the amount of data to be transmitted meets the requirements based on a second data amount threshold set for SDT, the amount of data to be transmitted meets the requirements based on a third data amount threshold set for at least one SDT mode, the channel quality between the first device 110 and the second device 120 meets the requirements based on a first quality threshold set for SDT, or the channel quality meets the requirements based on a second quality threshold set for at least one SDT mode.

[0085] In some exemplary embodiments, the first device 110 may determine whether the start of SDT is permitted in the second protocol layer by selecting one of a plurality of uplink carriers and determining whether the start of SDT on the selected uplink carrier is permitted.

[0086] In some exemplary embodiments, for a given uplink carrier among a plurality of uplink carriers, the first device 110 may determine whether the channel quality over the given uplink carrier meets the requirements based on a fourth quality threshold set for SDT or a fifth quality threshold set for an SDT mode, and may select one of the plurality of uplink carriers by selecting the given uplink carrier according to the determination that the channel quality meets the requirements based on the fourth quality threshold or the fifth quality threshold.

[0087] In some exemplary embodiments, the first device 110 may initiate the communication procedure of the SDT via the first protocol layer by causing a third protocol layer of the first device 110 (e.g., the PDCP layer 204) to send a third request to resume at least one radio bearer for the SDT from the first protocol layer. In some exemplary embodiments, the third protocol layer includes a packet data convergence protocol layer.

[0088] In some exemplary embodiments, a first device (e.g., the first device 110) capable of performing any of the methods 300 may include means for performing each operation of the method 300. The means may be implemented in any suitable form. For example, the means may be implemented as a circuit / or a software module. The first device may be implemented as the first device 110 or may be included in the first device 110.

[0089] In some exemplary embodiments, the first device includes means for determining whether initiation of small data transmission is permitted at a first protocol layer of the first device, means for determining whether initiation of small data transmission is permitted at a second protocol layer of the first device according to the determination that initiation of small data transmission is permitted at the first protocol layer, and means for initiating a communication procedure for small data transmission with a second device (e.g., the second device 120) via the first protocol layer according to the determination that initiation of small data transmission is permitted at the second protocol layer.

[0090] In some exemplary embodiments, the means for determining whether to permit the start of small data transmission in a first protocol layer determines that at least one of the following criteria is met: resources for small data transmission are configured; resources for at least one small data transmission mode are configured; data is available on at least one radio bearer for which small data transmission is permitted; or the amount of data to be transmitted meets the requirements based on a first data amount threshold set for small data transmission, and comprises means for determining that the start of small data transmission in the first protocol layer is permitted.

[0091] In some exemplary embodiments, at least one small data transmission mode includes at least one of the following: a first small data transmission mode based on a configured grant, a second small data transmission mode based on a random access procedure, a third small data transmission mode based on a two-step random access procedure, and a fourth small data transmission mode based on a four-step random access procedure.

[0092] In some exemplary embodiments, the first apparatus further comprises means for transmitting, from the first protocol layer to the second protocol layer, one of the following requests according to the determination that the start of small data transmission in the first protocol layer is permitted: a first request for determining whether to permit the start of small data transmission in the second protocol layer, or a second request for determining whether to permit the start of a target small data transmission mode in the second protocol layer.

[0093] In some exemplary embodiments, the means for determining whether to permit the start of small data transmission in the second protocol layer includes means for determining whether to permit the start of small data transmission in the second protocol layer in response to the first request, or means for determining whether to permit the start of the target small data transmission mode in the second protocol layer in response to the second request.

[0094] In some exemplary embodiments, the means for determining whether to permit the start of small data transmission in the second protocol layer includes means for determining whether to permit the start of at least one small data transmission mode in the second protocol layer.

[0095] In some exemplary embodiments, the first device further comprises means for causing an indication of the determined small data transmission mode to be transmitted from the second protocol layer to the first protocol layer in accordance with the determination that the start of one of at least one small data transmission mode in the second protocol layer is permitted. In some exemplary embodiments, the means for starting the communication procedure for small data transmission includes means for starting the communication procedure in accordance with the determined small data transmission mode via the first protocol layer in response to the indication of the determined small data transmission mode.

[0096] In some exemplary embodiments, the means for determining whether to permit the start of small data transmission in the second protocol layer includes the following criteria: the resources configured for small data transmission are valid; the resources configured for at least one small data transmission mode are valid; the amount of data to be transmitted meets the requirements based on a second data amount threshold set for small data transmission; the amount of data to be transmitted meets the requirements based on a third data amount threshold set for at least one small data transmission mode; the channel quality between the first device and the second device meets the requirements based on a first quality threshold set for small data transmission, or the channel quality meets the requirements based on a second quality threshold set for at least one small data transmission mode. The means for determining whether to permit the start of small data transmission in the second protocol layer includes determining that at least one of the above is satisfied.

[0097] In some exemplary embodiments, the means for determining whether to permit the start of small data transmission in the second protocol layer includes means for selecting one of a plurality of uplink carriers and means for determining whether to permit the start of small data transmission on the selected uplink carrier.

[0098] In some exemplary embodiments, the means for selecting one of a plurality of uplink carriers includes, for a given uplink carrier among the plurality of uplink carriers, means for determining whether the channel quality over the given uplink carrier meets the requirements based on a fourth quality threshold set for small data transmission or a fifth quality threshold set for a small data transmission mode, and means for selecting the given uplink carrier according to the determination that the channel quality meets the requirements based on the fourth quality threshold or the fifth quality threshold.

[0099] In some exemplary embodiments, the means for initiating a communication procedure for small data transmission via a first protocol layer includes means for causing a third request for resuming at least one radio bearer for small data transmission to be transmitted from the first protocol layer to a third protocol layer of a first device.

[0100] In some exemplary embodiments, the third protocol layer includes a packet data convergence protocol layer. In some exemplary embodiments, the first protocol layer includes a radio resource control layer, and the second protocol includes a media access control layer.

[0101] In some exemplary embodiments, the first device further comprises means for initiating further communication procedures for non-small data transmission with a second device via the first protocol layer in accordance with a determination that initiation of small data transmission is rejected at the first protocol layer or the second protocol layer.

[0102] In some exemplary embodiments, the first device further comprises means for performing method 400 or other operations in some exemplary embodiments of the first device 110. In some exemplary embodiments, the means comprises at least one processor and at least one memory including computer program code, and the at least one memory and the computer program code are configured to cause execution of the first device using the at least one processor.

[0103] FIG. 5 is a simplified block diagram of a device 500 suitable for implementing an exemplary embodiment of the present disclosure. The device 500 may be provided for implementing a communication device such as the first device 110 or the second device 120 shown in FIG. 1, for example. As shown, the device 500 includes one or more processors 510, one or more memories 520 connected to the processor 510, and one or more communication modules 540 connected to the processor 510.

[0104] The communication module 540 is for two-way communication. The communication module 540 has one or more communication interfaces that facilitate communication with one or more other modules or devices. The communication interface may represent any interface necessary for communication with other network elements. In some exemplary embodiments, the communication module 540 may include at least one antenna.

[0105] The processor 510 can be of any type suitable for a local technical network and can include, by way of non-limiting example, one or more of a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 500 can have multiple processors, such as an application-specific integrated circuit chip configured to keep time with a clock that synchronizes the main processor.

[0106] The memory 520 can include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 524, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic storage devices and / or optical storage devices. Examples of volatile memories include, but are not limited to, random access memory (RAM) 522 and other volatile memories that do not persist while the power is off.

[0107] The computer program 530 includes computer-executable instructions that are executed by the associated processor 510. The program 530 can be stored in a memory, such as ROM 524. The processor 510 can perform any suitable operations and processes by loading the program 530 into RAM 522.

[0108] Any process of the present disclosure discussed with reference to FIGS. 3-4 may be implemented by program 530 so that device 500 can execute it. Exemplary embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0109] In some exemplary embodiments, program 530 may be tangibly embodied on a computer-readable medium (such as memory 520) included in device 500 or on other storage devices accessible by device 500. Device 500 may load program 530 from the computer-readable medium into RAM 522 for execution. The computer-readable medium may include any type of tangible non-volatile storage device such as ROM, EPROM, flash memory, hard disk, CD, and DVD. FIG. 6 shows an example of a computer-readable medium 600, which may be in the form of a CD, DVD, or other optical storage disk. The computer-readable medium stores program 530.

[0110] Generally, various embodiments of the present disclosure may be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, the blocks, devices, systems, techniques, or methods described herein may be implemented, by way of non-limiting example, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controller or other computing device, or any combination thereof.

[0111] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, which, for example, are included in program modules and, when executed on a target physical processor or virtual processor, perform any of the methods described above with reference to FIGS. 3-4. Generally, program modules include routines, programs, libraries, objects, classes, components, or data structures, etc. that perform specific tasks or implement specific abstract data types. The functions of the program modules may be combined or divided among the program modules as desired in various embodiments. The machine-executable instructions of the program modules may be executed within a local device or within a distributed device. In a distributed device, the program modules are arranged on both a local storage medium and a remote storage medium.

[0112] The program code for executing the method of the present disclosure may be described in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device, such that when the program code is executed by the processor or controller, the functions / operations defined by the flowchart and / or block diagram are thereby implemented. The program code may be executed entirely on the machine, partially on the machine, executed as a stand-alone software package, executed partially on the machine and partially on a remote machine, or executed entirely on a remote machine or remote server.

[0113] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier so that a device, apparatus, or processor can execute the various processes and operations described above. Examples of carriers include signals and computer-readable media, etc.

[0114] A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0115] Furthermore, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed, to obtain desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although the above discussion includes some details of specific embodiments, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Specific features described in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable partial combination.

[0116] It should be understood that although the present disclosure has been described in terms of structural features and / or methodological acts, the present disclosure as defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the above-described specific features and acts are disclosed as exemplary forms for implementing the claims.

Claims

1. At least one processor, At least one memory including program code, A terminal device comprising: The at least one memory and the program code are configured to, using the at least one processor, determine that small data transmission is permitted to be initiated at an RRC protocol layer of the terminal device while the terminal device is in an inactive state of radio resource control (RRC); When it is determined that the small data transmission is permitted to be initiated at the RRC protocol layer, determine that the small data transmission is permitted to be initiated at a media access control (MAC) protocol layer of the terminal device; When it is determined that the small data transmission is permitted to be initiated at the MAC protocol layer, determine to resume at least one radio bearer for the small data transmission at the RRC protocol layer and initiate a communication procedure for the small data transmission with a network device; The terminal device configured to cause the terminal device to perform the above.

2. The at least one memory and the program code are further configured to, using the at least one processor, cause the terminal device to initiate the communication procedure for the small data transmission at the RRC protocol layer in response to an instruction from the MAC protocol layer indicating that the small data transmission is permitted to be initiated at the MAC protocol layer. The terminal device according to claim 1.

3. The at least one memory and the program code are further configured to, using the at least one processor, When it is determined that the small data transmission is permitted to be initiated at the RRC protocol layer, send a request from the RRC protocol layer to the MAC protocol layer to determine whether the small data transmission is permitted to be initiated at the MAC protocol layer; In response to the request, determine that the small data transmission is permitted to be initiated at the MAC protocol layer; When it is determined that the small data transmission is permitted to be initiated at the MAC protocol layer, send the instruction from the MAC protocol layer to the RRC protocol layer. ​ The terminal device according to claim 2, configured to cause the terminal device to execute.

4. The at least one memory and the program code, using the at least one processor, further When the small data transmission is permitted to be started in the RRC protocol layer, sending a request from the RRC protocol layer to the MAC protocol layer to determine whether the small data transmission mode is permitted to be started in the MAC protocol layer; In response to the request, determining that the small data transmission mode is permitted to be started in the MAC protocol layer; When the small data transmission mode is permitted to be started in the MAC protocol layer, sending a further instruction from the MAC protocol layer to the RRC protocol layer; In response to the further instruction, starting the communication procedure of the small data transmission via the RRC protocol layer according to the small data transmission mode; The terminal device according to claim 1, configured to cause the terminal device to execute.

5. The at least one memory and the program code, using the at least one processor, further configured to cause the terminal device to determine that the small data transmission is permitted to be started in the RRC protocol layer by determining that resources for the small data transmission are set. The terminal device according to claim 1.

6. The at least one memory and the program code, using the at least one processor, further configured to cause the terminal device to determine that the small data transmission is permitted to be started in the RRC protocol layer by determining that resources for the small data transmission mode are set. The terminal device according to claim 1.

7. The at least one memory and the program code are configured to cause the terminal device to further determine, by using the at least one processor, that data is available in at least one radio bearer permitted for the small data transmission, and thereby determine that the small data transmission is permitted to be started in the RRC protocol layer, according to the terminal device of claim 1.

8. The at least one memory and the program code are configured to cause the terminal device to further determine, by using the at least one processor, that the amount of data to be transmitted meets the requirements based on a data amount threshold set for the small data transmission, and thereby determine that the small data transmission is permitted to be started in the RRC protocol layer, according to the terminal device of claim 1.

9. The small data transmission mode includes one of the following: Small data transmission mode based on configured grant, Small data transmission mode based on random access procedure, Small data transmission mode based on two-step random access procedure, and Small data transmission mode based on four-step random access procedure, according to the terminal device of claim 4 or 6.

10. The at least one memory and the program code are configured to cause the terminal device to further determine, by using the at least one processor, that the resources set for the small data transmission are valid, and thereby determine that the small data transmission is permitted to be started in the MAC protocol layer, according to the terminal device of claim 1.

11. The at least one memory and the program code are configured to cause the terminal device to further determine, by using the at least one processor, that the resources set for the small data transmission mode are valid, and thereby determine that the small data transmission is permitted to be started in the MAC protocol layer, according to the terminal device of claim 1.

12. The at least one memory and the program code are configured to cause the terminal device to, using the at least one processor, further determine that the amount of data to be transmitted meets the requirements based on a data amount threshold set for the small data transmission, and thereby determine that the small data transmission is permitted to be started at the MAC protocol layer, the terminal device according to claim 1.

13. The at least one memory and the program code are configured to cause the terminal device to, using the at least one processor, further determine that the amount of data to be transmitted meets the requirements based on a data amount threshold set for the small data transmission mode, and thereby determine that the small data transmission is permitted to be started at the MAC protocol layer, the terminal device according to claim 1.

14. The at least one memory and the program code are configured to cause the terminal device to, using the at least one processor, further determine that the channel quality between the terminal device and the network device meets the requirements based on a quality threshold set for the small data transmission, and thereby determine that the small data transmission is permitted to be started at the MAC protocol layer, the terminal device according to claim 1.

15. The at least one memory and the program code are configured to cause the terminal device to, using the at least one processor, further determine that the channel quality between the terminal device and the network device meets the requirements based on a quality threshold set for the small data transmission mode, and thereby determine that the small data transmission is permitted to be started at the MAC protocol layer, the terminal device according to claim 1.

16. The at least one memory and the program code are configured to, using the at least one processor, further select one of a plurality of uplink carriers; determine whether the small data transmission is permitted to be started on the one of the plurality of uplink carriers; The terminal device according to claim 1, configured to cause the terminal device to execute.

17. The at least one memory and the program code further use the at least one processor to, for a given uplink carrier of the plurality of uplink carriers, determine whether the channel quality between the terminal device and the network device over the given uplink carrier meets the requirements based on a quality threshold set for the small data transmission or for the small data transmission mode; select the given uplink carrier when the channel quality meets the requirements based on the quality threshold; The terminal device according to claim 16, configured to cause the terminal device to execute.

18. The at least one memory and the program code further use the at least one processor to cause the terminal device to transmit a request from the RRC protocol layer to the packet data convergence protocol (PDCP) protocol layer of the terminal device to resume the at least one radio bearer for the small data transmission, the terminal device according to claim 1.

19. The at least one memory and the program code further use the at least one processor to start a further communication procedure for non-small data transmission with the network device via the RRC protocol layer when it is rejected that the small data transmission is started in the RRC protocol layer or the MAC protocol layer; The terminal device according to claim 1, configured to cause the terminal device to execute.

20. A method for the terminal device while the terminal device is in an inactive state of radio resource control (RRC), comprising: determining that it is permitted for small data transmission to be started in the RRC protocol layer of the terminal device; when it is determined that it is permitted for the small data transmission to be started in the RRC protocol layer, determining whether it is permitted for the small data transmission to be started in the media access control (MAC) protocol layer of the terminal device; When permission is given for the small data transmission to start at the MAC protocol layer, in the RRC protocol layer, resume at least one radio bearer for the small data transmission and determine to start the communication procedure of the small data transmission with the network device. The method including the above.

21. A computer-readable storage medium storing program instructions for causing at least the apparatus to execute the method according to Claim 20.

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