Mobility of small data transmission process

Abstract

Embodiments of the present disclosure relate to the mobility of a small data transmission (SDT) process. A first device that is in an inactive state and is served in a first cell of a second device performs a session of small data transmission between the first device and the second device. The first device determines whether a potential cell reselection criterion is met when the session of small data transmission is ongoing. If the potential cell reselection criterion is met, the first device sends a first message indicating a cell reselection intention to the second device. In this way, if cell reselection occurs during the SDT process, the second device is able to place the first device in an inactive state or a connected state. Therefore, in the case where cell reselection occurs before the session of small data transmission is completed, the data that has been sent will not be lost.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of telecommunications, and in particular to methods, devices, apparatuses, and computer-readable storage media for mobility of a small data transmission process. Background Art

[0002] In some communication systems, a terminal device may transition between an inactive state and a connected state. In the inactive state, the terminal device may not have established a connection with a network device for communication. In order to avoid unnecessary signaling overhead and power consumption for establishing or re-establishing a connection, it has been agreed to support small data transmission (SDT) for terminal devices in an inactive state without requiring the terminal device to establish a connection with the network device.

[0003] In addition, as part of SDT, a terminal device in an inactive state can send multiple uplink packets and receive multiple downlink packets without having to transition to a connected state upon a dedicated grant. That is, the terminal device sends multiple packets during the same SDT process without having to transition to a connected state in between or perform a separate SDT process for sending. Summary of the invention

[0004] In general, example embodiments of the present disclosure provide a solution for the mobility of an SDT process.

[0005] In a first aspect, a first device is provided. The first device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, enable the device to: perform a session of small data transmission between a first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; determine whether a potential cell reselection criterion is met when the session of small data transmission is ongoing, and send first information indicating a cell reselection intention to the second device based on the determination that the potential cell reselection criterion is met.

[0006] In a second aspect, a second device is provided. The second device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, enable the device to: perform a session of small data transmission between a first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; and receive first information indicating a cell reselection intention from the first device.

[0007] In a third aspect, a third device is provided. The third device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, enable the device to: receive an indication from a first device whether a session for small data transmission is being conducted between the first device and the second device in a first cell of the second device; and receive data of the session for small data transmission from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell.

[0008] In a fourth aspect, a method is provided. The method includes a first device performing a session of small data transmission between the first device and a second device, the first device being inactive and being served in a first cell of the second device; determining whether a potential cell reselection criterion is satisfied when the session of small data transmission is ongoing; and sending first information indicating a cell reselection intention to the second device based on a determination that the potential cell reselection criterion is satisfied.

[0009] In a fifth aspect, a method is provided, comprising: performing a small data transmission session between a first device and a second device at a second device, the first device being inactive and being served in a first cell of the second device; and receiving first information indicating a cell reselection intention from the first device.

[0010] In a sixth aspect, a method is provided. The method includes receiving, at a third device, an indication of whether a session for small data transmission is being performed between the first device and the second device in a first cell of the second device from a first device; and receiving data of the session for small data transmission from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell.

[0011] In a seventh aspect, a first device is provided. The first device includes a component for performing a session of small data transmission between the first device and a second device, the first device being inactive and being served in a first cell of the second device; a component for determining whether a potential cell reselection criterion is satisfied when the session of small data transmission is ongoing; and a component for sending first information indicating a cell reselection intention to the second device based on a determination that the potential cell reselection criterion is satisfied.

[0012] In an eighth aspect, a second device is provided. The second device includes a component for performing a session of small data transmission between a first device and a second device at the second device, the first device being in an inactive state and being served in a first cell of the second device; and a component for receiving first information indicating a cell reselection intention from the first device.

[0013] In a ninth aspect, a third device is provided. The third device includes a component for receiving an indication from a first device whether a session for small data transmission is being performed between the first device and the second device in a first cell of the second device; and a component for receiving data of the session for small data transmission from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell.

[0014] In a tenth aspect, a computer-readable medium is provided, the computer-readable medium comprising program instructions for causing an apparatus to at least execute a method according to any one of the fourth to sixth aspects above.

[0015] It should be understood that the invention summary is not intended to determine the key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0017] Figure 1 shows an example communication network in which example embodiments of the present disclosure may be implemented;

[0018] Figure 2 shows a signaling flow for cell reselection during an SDT procedure according to some example embodiments of the present disclosure;

[0019] Figure 3 shows a signaling flow for cell reselection during an SDT procedure according to some other example embodiments of the present disclosure;

[0020] Figure 4 shows a signaling flow for cell reselection during an SDT procedure according to some other example embodiments of the present disclosure;

[0021] Figure 5 shows a signaling flow for cell reselection during an SDT procedure according to some other example embodiments of the present disclosure;

[0022] Figure 6 shows a signaling flow for unified access control (UAC) processing in cell reselection during an SDT procedure according to some example embodiments of the present disclosure;

[0023] Figure 7 A flowchart showing a method implemented at a first device according to some example embodiments of the present disclosure is shown;

[0024] Figure 8 A flowchart showing a method implemented at a second device according to some example embodiments of the present disclosure is shown;

[0025] Fig. 9 A flowchart showing a method implemented at a third device according to some other example embodiments of the present disclosure is shown;

[0026] Fig.10 shows a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

[0027] Fig.11 A block diagram of an example computer-readable medium is shown according to some example embodiments of the present disclosure.

[0028] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0029] The principle of the present disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described only to illustrate and help those skilled in the art to understand and implement the present disclosure, and do not represent any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various other ways except the way described below.

[0030] In the following description and claims, unless defined otherwise, 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.

[0031] In this disclosure, references to "one embodiment," "an embodiment," and "an example embodiment" indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include the particular feature, structure, or characteristic. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, those skilled in the art believe that it is within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0032] It should be understood that although the terms "first" and "second" etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0033] The terms used herein are only used to describe specific embodiments and are not intended to limit the example embodiments. As used herein, the singular forms "a", "an", and "the" also include the plural forms, unless the context clearly indicates otherwise. It is further understood that the terms "comprises", "comprising", "has", "having", "includes", and / or "including" when used herein specify the presence of the features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0034] As used in this application, the term "circuitry" may refer to one, more, or all of the following:

[0035] (a) a pure hardware circuit implementation (such as an implementation using only analog and / or digital circuitry), and

[0036] (b) a combination of hardware circuitry and software such as (where applicable):

[0037] (i) a combination of analog and / or digital hardware circuits and software / firmware, and

[0038] (ii) any portion of a hardware processor(s) with software, including digital signal processor(s), software and memory(s), which work together to enable a device (such as a mobile phone or server) to perform various functions, and

[0039] (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), which requires software (e.g., firmware)

[0040] The software can be saved when no operation is needed.

[0041] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0042] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as Long Term Evolution (LTE), Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. In addition, the communication between the terminal device and the network device in the communication network can be performed according to any suitable generation of communication protocol, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocol, and / or any other protocol currently known or to be developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there will certainly be future types of communication technologies and systems that can embody the present disclosure. The scope of the present disclosure should not be limited to the above-mentioned systems.

[0043] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. A network device may refer to a base station (BS) or an access point (AP), for example, a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), an integrated and access backhaul (IAB) node, a relay, a low power node (such as a femto, a pico), etc., depending on the terminology and technology applied.

[0044] The term "terminal device" refers to any terminal device capable of wireless communication. As an 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 portable subscriber station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device (such as a digital camera), a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop vehicle-mounted device (LME), a USB dongle, a smart device, a wireless customer premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0045] As used herein, the term "resource", "transmission resource", "resource block", "physical resource block" (PRB), "uplink resource" or "downlink resource" may refer to any resource used to perform communication (e.g., communication between a terminal device and a network device), such as a resource in the time domain, a resource in the frequency domain, a resource in the space domain, a source in the code domain, or any other resource capable of communication. In the following, resources in both the frequency domain and the time domain will be used as examples of transmission resources to describe some example embodiments of the present disclosure. Note that the example embodiments of the present disclosure are also applicable to other resources in other domains.

[0046] Example Environment

[0047] First reference Figure 1 , Figure 1 An example communication network is shown in which example embodiments of the present disclosure may be implemented. Figure 1 An example communication network 100 is shown in which example embodiments of the present disclosure may be implemented. In the example communication network 100, a plurality of communication devices including a first device 110, a second device 120, and a third device 130 may communicate with each other.

[0048] exist Figure 1In the example of FIG. 1 , the first device 110 is shown as a terminal device, and the second device 120 and the third device 130 are shown as network devices that can serve the terminal device. The service area of ​​the second device 120 can be called a cell 102. At the same time, the second device 120 can serve multiple cells. Figure 1 As shown, the second device 120 also serves the cell 103. The service area of ​​the third device 130 may be referred to as the cell 104.

[0049] The first device 110 currently being served in the cell 103 may move out of the coverage of the cell 103 and move to the cell 102. In this case, the first device 110 will perform cell reselection and be served by the same network device (i.e., the second device 120) before and after the cell reselection. In other cases, the first device 110 served by the second device 120 may move out of the coverage of the cell 102 and move to the cell 104 of the third device 130. In this case, the first device 110 may perform cell reselection and be served by the third device 130 after the cell reselection or handover process.

[0050] It should be understood that Figure 1 The number of devices shown and their connections are for illustrative purposes only, without any limitation. The example communication network 100 may include any suitable number of devices suitable for implementing embodiments of the present disclosure. Although not shown, it should be understood that one or more additional devices may be located in the cell 102, the cell 103, and the cell 104, and one or more additional cells may be deployed in the example communication network 100. Note that, although shown as network devices, the second device 120 and the third device 130 may correspond to other devices other than the network devices. Although shown as terminal devices, the first device 110 may correspond to other devices other than the terminal devices.

[0051] In some example embodiments, if 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 called a downlink (DL), and the link from the first device 110 to the second device 120 is called an uplink (UL). In the DL, the second device 120 is a transmitting (TX) device (or transmitter), and the first device 110 is a receiving (RX) device (or receiver). In the UL, the first device 110 is a TX device (or transmitter), and the second device 120 is an RX device (or receiver).

[0052] Communications in the example communication network 100 may be implemented according to any appropriate communication protocol(s), including but not limited to cellular communication protocols of 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 currently known or to be developed in the future. In addition, communications may utilize any appropriate wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology currently known or to be developed in the future.

[0053] The 3GPP working group has introduced a feature called an inactive state. A device (e.g., a terminal device) can transition between an inactive state, a connected state, and an idle state. The inactive state may sometimes be referred to as an inactive mode, an RRC_INACTIVE state, an inactive state in an RRC_CONNECTED mode, and such terms may be used interchangeably herein. The connected state may sometimes be referred to as a connected mode, an RRC_CONNECTED state, and such terms may be used interchangeably herein. The idle state may sometimes be referred to as an idle mode, an RRC_IDLE state, and such terms may be used interchangeably herein.

[0054] In the inactive state, the terminal device may not have any dedicated resources (e.g., time and frequency resources) for sending and / or receiving. In the connected state, a connection is established between the terminal device and the network device, and the terminal device can therefore perform normal communication with the network device via the connection. In the idle state, no connection is established between the terminal device and the network device. The idle state can be used, for example, during power-on of the terminal device. Once the establishment process is completed, the terminal device can transition to the connected state and be ready for data transmission.

[0055] As described above, transitioning a terminal device from an inactive state to a connected state by establishing or re-establishing a connection with a network device requires a certain amount of signaling overhead and power consumption. If a connection establishment and subsequent release occurs for each data transmission for an inactive terminal device, no matter how small and infrequent the data packets are, this may result in unnecessary power consumption and signaling overhead. Therefore, if a terminal device has intermittent small data packets to send, it makes sense to allow data transmission to and / or from an inactive terminal device. It has been agreed to support small data transmission (SDT) for an inactive terminal device without the need for the terminal device to establish a connection with a network device. As used herein, the term "SDT" refers to a type of transmission in which a small amount of data is triggered, although other terms may also be used.

[0056] There are various applications involving relatively small amounts of data exchange. For example, in some applications on mobile devices, SDT may include services from instant messaging (IM) services, heartbeat or keep-alive services from IM or email clients and other services, push notifications in various applications, services from wearable devices (e.g., including periodic location information), etc. In some applications on non-mobile devices, SDT may include sensor data (e.g., temperature, pressure readings sent periodically or in an event-triggered manner in an IoT network), metering and alarm information sent from smart meters, etc.

[0057] For small data packets, signaling overhead from inactive terminal devices is a common problem, not only for network performance and efficiency, but also for UE battery performance. In general, any device with intermittent small data packets in an active state will benefit from enabling SDT. In some example embodiments, SDT can be enabled using a configured grant and / or a message sent during a random access channel (RACH) procedure.

[0058] Furthermore, as described above, it has been agreed in 3GPP that a terminal device in an inactive state can send and / or receive multiple uplink and / or downlink packets during an SDT process without transitioning to a connected state in between or performing a separate SDT process for packet transmission.

[0059] However, the inventors of the present application have noticed that, according to the conventional radio resource control (RRC) recovery process, when cell reselection occurs during the process (i.e., when the timer (e.g., T319) for the process starts running after the RRC recovery request is sent), the terminal device will enter the idle state. Therefore, in this scenario, there is no existing solution for handling cell reselection. In addition, with the agreement to perform continuous uplink or downlink transmission without transitioning to the connected state, it is no longer a rare case that cell reselection occurs during the SDT process. When the UE performs an SDT transmission in an inactive state, it is not desirable to enter the idle state because this will result in the loss of data that has already been sent. Therefore, a solution for the mobility of the SDT process is needed.

[0060] Cell reselection during SDT procedure

[0061] As described above, the inventors of the present application have noticed that, according to the conventional radio resource control (RRC) recovery procedure, when cell reselection occurs during the procedure (i.e., when a timer (e.g., T319) for the procedure starts running after sending an RRC recovery request and has not expired), the first device 110 transitions to the idle state. In addition, if the first device 110 in the inactive state enters the idle state, the first device 110 may have to perform an RRC establishment procedure with the second device 120 in order to transition to the connected state. In this case, the second device 120 (e.g., gNB) does not continue to maintain the context information of the first device 110 in the idle state. In this way, if the first device 110 moves from the old cell to the new cell, the third device 130 for the new cell can neither retrieve the UE context information from the second device 120 for the old cell nor retrieve the data that has been sent from the second device 120 for the old cell. Therefore, the packets that have been sent to the old cell during the SDT procedure will be lost. At the same time, there will be more delays because the connection needs to be established again. Therefore, for the reasons described above, it is undesirable to place the first device 110 in an idle state during the SDT process in an inactive state.

[0062] In addition, with the agreement to perform continuous uplink or downlink transmission without transitioning to the connected state, it is no longer a rare case that cell reselection occurs during the SDT process. In addition, as described above, when the first device 110 performs SDT transmission in the inactive state, it is not desirable to enter the idle state due to the loss of the data that has been sent and the significant delay. Therefore, for the first device 110 in the inactive state, a solution for cell reselection during the SDT process is needed.

[0063] According to some example embodiments of the present disclosure, a solution for mobility of an SDT process is provided. In this solution, a first device that is in an inactive state and served in a first cell of a second device performs a session of small data transmission between the first device and the second device. The first device determines whether the potential cell reselection criterion is met when the session of small data transmission is ongoing. If the potential cell reselection criterion is met, the first device sends a first information indicating the intention of cell reselection to the second device. In this way, if cell reselection occurs during the SDT process, the second device is able to place the first device in an inactive state or a connected state, so that the second device will retain the data that has been sent during the SDT process and the context information of the first device, so that when reselecting to a new cell, the above context information and data can be forwarded to a third device for the new cell. Therefore, in the case where cell reselection occurs before the session of small data transmission is completed, the data that has been sent will not be lost. It is also possible to avoid the error situation in which the first device returns to an idle state.

[0064] Reference now Figure 2 , Figure 2 FIG. 2 shows a signaling flow 200 for performing cell reselection during an SDT process according to an embodiment of the present disclosure. For ease of discussion, reference will be made to FIG. Figure 1 Describe the signaling flow 200. The signaling flow 200 may involve such Figure 1 A first device 110 , a second device 120 , and a third device 130 are shown.

[0065] In signaling flow 200, a first device 110 in an inactive state is located in a cell (e.g., cell 103) of a second device 120 and is served therein. For ease of discussion, the cell in which the first device 110 is currently served is sometimes referred to as a first cell. The first device 110 in an inactive state performs 202 a SDT session with the second device 120. In some examples, the first device 110 may send uplink small data to the second device 120. In some other examples, the first device 110 may receive downlink small data from the second device 120.

[0066] First device 110 determines 204 whether potential cell reselection criteria are met while a session of SDT is ongoing. In some example embodiments, first device 110 may determine that potential cell reselection criteria are met if first device 110 moves to a border of cell 103 or moves out of coverage of cell 103 during the SDT process.

[0067] In some example embodiments, the potential cell reselection criteria may be related to a reference signal received power (RSRP) at the first device 110 and / or a signal to interference and noise ratio (SINR) at the first device 110 and / or a reference signal received quality (RSRQ) at the first device 110. For example, if the first device 110 moves during the SDT process and the RSRP at the first device 110 becomes lower than a predetermined threshold, it is determined that the potential cell reselection criteria are met. Alternatively or additionally, if the SINR at the first device 110 is lower than a specific threshold, it is determined that the potential cell reselection criteria are met. Alternatively or additionally, if the RSRQ at the first device 110 is lower than a specific threshold, it is determined that the potential cell reselection criteria are met. It should be understood that the potential cell reselection criteria may be in any form and is not limited to the above examples. The scope of the present disclosure is not limited in this regard.

[0068] When a potential cell reselection criterion is met while a session of SDT is ongoing (e.g., when T319 or other timer for the SDT process is running), the first device 110 sends 206 information indicating a cell reselection intention to the second device 120 (referred to as "first information" for ease of discussion). That is, the first device 110 notifies the second device 120 that a cell reselection is about to occur. In this way, by receiving 208 the first information from the first device 110, the second device 120 can keep the first device 110 in an inactive state or transition to a connected state, which can avoid the first device 110 from being placed in an idle state. In this way, the context information of the first device 110 may not be deleted from the second device 120, and thus may be used in the event that a cell reselection for the first device 110 actually occurs.

[0069] In some example embodiments, an offset or a separate threshold may be defined for the potential cell reselection criteria, which will trigger the above-mentioned reporting of the first information before the criteria for the actual cell reselection are met. In this way, the second device 120 is notified in advance (i.e., before the actual cell reselection) of the occurrence of the cell reselection. With the advance notification of the cell reselection intention, the second device 120 may have more time to react and, for example, put the first device 110 into an inactive or connected state in the event that the cell reselection is about to occur. In this way, the erroneous situation of the first device 110 returning to the idle state may be avoided.

[0070] In some example embodiments, the potential cell reselection criteria may also be determined by the first device 110 based on an existing criterion configured to actually trigger cell reselection. In some other examples, the potential cell reselection criteria may also be configured separately.

[0071] In some example embodiments, the first information may include an identification of a cell (e.g., cell 102 or 104) to be reselected by the first device 110. For ease of discussion, the cell to be reselected is sometimes referred to as a second cell. In some example embodiments, the first information may be sent via a media access control control element (MAC-CE) or an RRC message. In some example embodiments, the first information may include an explicit indication that a potential cell reselection criterion is met. Alternatively or additionally, the first information may include an indication of whether the first device 110 prefers an inactive state or a connected state.

[0072] In some example embodiments, the first information (e.g., an RRC message) may be in the form of a radio resource management (RRM) measurement result (e.g., a measurement report). In some example embodiments, the RRC message may include UE assistance information. That is, for example, the satisfaction of a potential cell reselection criterion serves as a trigger for a UE assistance information process in which the first device 110 may send an RRC state preference (e.g., an inactive state or a connected state) to the second device 120. By receiving such an RRC state preference, the second device 120 may determine that a cell reselection of the first device 110 is about to occur based on the state preference.

[0073] In some example embodiments, the first device 110 may perform a cell reselection to the third device 130. In some other example embodiments, a handover process may be performed such that the first device 110 will handover to the third device 130. Figure 3 and Figure 4 Describe the detailed process.

[0074] Figure 3 A signaling flow 300 for cell reselection during an SDT process according to some embodiments of the present disclosure is shown. For ease of discussion, reference will be made to Figure 1 Describe the signaling flow 300. The signaling flow 300 may involve such Figure 1 A first device 110 , a second device 120 , and a third device 130 are shown.

[0075] The actions at 302, 304, 306, and 308 in the signaling flow 300 are similar to Figure 2 The actions at 202, 204, 206, and 208 in FIG. 1 are therefore incorporated herein in detail.

[0076] like Figure 3 As shown, the second device 120 receives 308 first information indicating a cell reselection intention from the first device 110. The second device 120 can then place the first device 110 in an inactive state or a connected state. In this case, the cell reselection can occur as usual in the inactive state.

[0077] exist Figure 3 In the example embodiment of , the second device 120 sends 310 to the first device 110 information for switching the first device 110 from the first cell (eg, cell 103) to the second cell of the third device. For ease of discussion, such information is referred to as second information.

[0078] As an embodiment of sending the second information, the second device 120 may send 310 to the first device 110 first control information for instructing the first device 110 to maintain the inactive state. According to such first control information, the first device 110 may switch from the first cell to the second cell while the first device 110 remains in the inactive state.

[0079] Specifically, in some example embodiments, upon receiving the first information indicating the cell reselection intention, the RRC connection between the second device 120 and the first device 110 in an inactive state is released so that the first device 110 can continue the SDT session in the new cell (i.e., the second cell). In such an embodiment, the second device 120 sends an RRC message (e.g., an RRC release message) with "suspendConfig" to the first device 110. In some examples, the second device 120 can update the first device 110 with a new security configuration by including the security configuration to be used in the communication with the second cell in the RRC release message. For example, the security configuration may include an inactive radio network temporary identifier (I-RNTI), a next hop chain count (NCC), and / or any other information required in the communication with the new cell. In this way, the first device 110 can use the security configuration when accessing the second cell.

[0080] In some example embodiments, upon receiving 312 the second information, e.g., upon receiving the first control information including “suspendConfig” in the RRC release message at the first device 110, the first device 110 may suspend the connection (e.g., the RRC connection) through which the session of the SDT is sent, and reselect 314 the second cell.

[0081] In some example embodiments, upon receiving the second information, first device 110 reselects 314 a new cell (referred to as a second cell) to perform cell reselection while first device 110 remains in an inactive state. In one example, first device 110 performs cell reselection from a first cell (e.g., cell 103) of second device 120 to a second cell. In one example, the second cell may be cell 103 of third device 130. In such an example, cell reselection involves first device 110, second device 120, and third device 130, such as Figure 3In other examples, the second cell may be the cell 102 of the same second device 120, and thus the entities involved in the cell reselection may include the first device 110 and the second device 120. For illustrative purposes only, the third device 130 is involved in the signaling flow 300, but it should be understood that if the second cell is selected as the cell 102, the same actions may be performed at the second device 120.

[0082] Thereafter, in some example embodiments, first device 110 sends 316 a recovery request to third device 130 for recovering or re-initiating a session of SDT in the second cell. The recovery request may be sent via a common control channel (CCCH). In this case, in response to third device 130 receiving 318 the recovery request, context retrieval and data forwarding may be performed between the first cell and the second cell.

[0083] Additionally or alternatively, in some example embodiments, upon reselection of a new cell, the first device 110 further sends 320 an indication to the third device 130 that the session of the SDT is ongoing in the first cell. In one example, the indication may be sent by the first device 110 via a MAC-CE message. In another example, the indication may be sent by the first device 110 via an RRC message.

[0084] After receiving the 322 indication, the third device 130 may know that there is an ongoing SDT process between the first device 110 and the second device 120. If it is determined that the first device 110 switches from the first cell to the second cell of the third device 130, the third device 130 receives data of the session of small data transmission from the second device 120. The data may include such data that has been sent to the second device 120 while the first device 110 is served in the first cell. In some example embodiments, when the third device 130 has just received data from the first device 110, the data may not be processed, and the third device 130 will wait until the forwarded data from the first device 110 that has been sent is received, so that the data that has been sent can be combined and processed together with the data directly received from the first device 110. As a result, the mobility of the SDT process in the inactive state is supported, and the packet loss is less.

[0085] In particular, in some examples, the third device 130 requests 324 to retrieve context information of the first device 110 from the second device 120 using the identification of the first device 110. Since the second device 120 sets the first device 110 to a connected state or an inactive state, it can still maintain the context information of the first device 110. Therefore, the second device 120 sends 326 the context information of the first device 110 to the third device 130. In this way, the connection between the first device 110 and the third device 130 does not need to be established again from the beginning, thereby reducing the delay of the cell reselection process.

[0086] In addition, in some example embodiments, the second device 120 may also forward 328 the already transmitted data to the third device 130. In some examples, the already transmitted data may be uplink data that the first device 110 has transmitted to the second device 120 during the SDT process. In some other examples, the already transmitted data may also be downlink data transmitted from the core network to the second device 120. The scope of the present application is not limited in this respect. Therefore, the already transmitted packets will not be lost.

[0087] In some example embodiments, after receiving 330 the data forwarded from the second device 120, the third device 130 may combine the data with the data received directly from the first device 110 in a session of SDT.

[0088] In some example embodiments, the first device 110 may also perform an RRC re-establishment procedure by sending a re-establishment request to the third device 130 for re-initiating a session of SDT in the second cell. In some examples, the re-establishment procedure may be limited to a case where the first device 110 (e.g., UE) has been allocated a cell radio network temporary identifier (C-RNTI) in a previous cell during the SDT procedure (which the first device 110 subsequently uses for re-establishment). The first device 110 may include the C-RNTI in the RRC re-establishment request message to the second cell. In some examples, based on the re-establishment request from the first device 110, the third device 130 may determine the previous cell in which the first device 110 is performing the SDT procedure, for example, by indicating a physical cell identity (PCI) as part of the re-establishment message by the first device 110, and may determine the cell and / or network device (e.g., the second network device 120) from which the UE context and / or the SDT data that has been sent is to be requested. In some examples, the new I-RNTI and NCC may have been signaled on the source cell so that the UE performs the re-establishment.

[0089] Figure 4FIG. 4 shows a signaling flow for performing cell reselection during an SDT process according to some other exemplary embodiments of the present disclosure. Figure 1 Describe the signaling flow 400. The signaling flow 400 may involve such Figure 1 A first device 110 , a second device 120 , and a third device 130 are shown.

[0090] Figure 4 Steps 402, 404, 406, 408 shown are similar to Figure 2 The steps 202, 204 and 206, 208 shown are similar, so the details will be incorporated here. As described above, the first device 110 sends 406 the first information to the second device 120. Figure 4 In some example embodiments, after receiving the first information from the first device 110, the second device 120 sends 410 second information including second control information, and the second control information is used to indicate that the first device 110 transitions from the current inactive state to the connected state. In one example, the second device 120 may send 410 an RRC recovery message to set the first device 110 to the connected state. In some examples, after receiving 412 the RRC recovery message, the first device 110 may perform a state transition from the inactive state to the connected state. In such an example, a conventional handover process may be performed so that the first device 110 can switch from the first cell to the second cell. In such an example, the handover command may be sent after the RRC recovery is completed, or sent in conjunction with the RRC recovery in the same MAC PDU.

[0091] Additionally or alternatively, as described above, in some example embodiments, the first information may include an identification of a second cell (e.g., cell 104) to be reselected by the first device 110. In such an example embodiment, upon receiving the first information, the second device 120 may perform a handover preparation process with the third device 130 by sending 420 a handover request message to the third device 130. After receiving 422 the handover request message, the third device 130 performs 424 admission control. In an example embodiment, the third device 130 may give priority to granting the handover request. For example, the first device 110 in an inactive state may be assigned a relatively low priority for admission (compared to other terminal devices in a connected state). In an example embodiment, the third device 130 may grant a handover request for the first device 110 in an inactive state by considering the priority and currently available resources.

[0092] In some example embodiments, after performing admission control, the third device 130 sends 426 a handover request confirmation to the second device 120. After receiving 428 the handover request confirmation, the second device 120 sends 410 an RRC resume message with a handover command to the first device 110. The handover command indicates an identity of a second cell for handover in order to handover the first device 110 to the cell to which it intends to reselect. In particular, upon receiving 412 the RRC resume message with the handover (HO) command, the first device 110 performs 430 a RACH to the second cell and continues data transmission in a connected state.

[0093] In the above, some example embodiments of a solution for performing cell reselection during an SDT process are introduced. In such example embodiments, the second device 120 is involved during the cell reselection process. In the following, a different solution will be introduced. In this solution, the second device 120 does not need to be involved during the cell reselection process, but is only involved when a session of SDT is performed between the first device 110 and the second device 120.

[0094] Figure 5 A signaling flow 500 for cell reselection during an SDT process according to some embodiments of the present disclosure is shown. For ease of discussion, reference will be made to Figure 1 Describe the signaling flow 500. The signaling flow 500 may involve such Figure 1 A first device 110 , a second device 120 , and a third device 130 are shown.

[0095] like Figure 5 As shown, a SDT session is performed 502 between the first device 110 and the second device 120. During the SDT session, the second device 120 can send a security configuration to the first device 110 in response to an SDT transmission (e.g., a first SDT transmission) performed by the first device 110. In some examples, the security configuration can include a new I-RNTI and NCC. In this way, with the security configuration, the first device 110 can perform 504 cell reselection in advance by itself when necessary (e.g., when the potential cell reselection criteria are met) without entering an idle state.

[0096] The foregoing describes some embodiments in which, while SDT is ongoing, the first device 110 performs cell reselection according to information provided by the second device 120. In some embodiments, while SDT is ongoing, if cell reselection is to be performed, the first device 110 may also determine whether mobility is allowed.

[0097] In some example embodiments, first device 110 may further determine whether mobility during the SDT procedure is allowed. Mobility during the small data transmission procedure means switching of first device 110 from the first cell while a session of small data transmission is ongoing.

[0098] In some example embodiments, the first device 110 may receive configuration information associated with mobility from the second device 120 during the SDT process.

[0099] In some example embodiments, the configuration information may include an indication of whether mobility during the SDT process is allowed for the first device 110, an indication of whether the second device 120 supports mobility during the SDT, at least one cell in which mobility during the SDT process is allowed, at least one device that allows mobility during the SDT process, and an area in which mobility during the SDT process is supported, or an indication of whether the SDT process is limited to the first cell.

[0100] The first device 110 may determine whether mobility during the SDT process is allowed based on one or more of the above configuration information. Then, if it is determined that mobility during the SDT process is allowed, the first device 110 may send first information indicating a cell reselection intention.

[0101] In some example embodiments, first device 110 may receive an indication of whether SDT is limited to the first cell from second device 120. If it is determined that the indication indicates that SDT is not limited to the first cell, first device 110 may perform SDT in the second cell after switching to the second cell.

[0102] In some embodiments, a timer indicating how long the SDT process is to proceed (e.g., when T319 or other timer for the SDT process is running) is extended and / or adapted to support longer SDT sessions. In some examples, new start and / or restart and / or stop conditions may be defined for the timer (e.g., T319), which may include one or more of the following: after each new UL transmission after the first transmission of the SDT is performed (this may or may not mean that retransmissions are not considered); or after a MAC-level contention resolution has been received (e.g., the random access process is successfully completed and / or the contention resolution is considered successful); or a DL transmission is received after the first SDT transmission; or the second device 120 explicitly indicates a stop / (re)start, for example, via physical layer, MAC layer, or RRC layer signaling; or a MAC-level contention resolution (MSG4) as described above is received without an RRC message; or when the UL and / or DL ​​SDT is completed; or based on a PDCCH indicating a new transmission (DL or UL) for the first device 110. In some examples, the first SDT transmission can be MSGA of a 2-step random access procedure, or Msg3 of a 4-step random access procedure, or the first transmission on a configured granted resource configured for SDT. In some examples, when an RRCConnectionResumeRequest (or any other RRC message defined for this purpose) is sent for SDT or when an SDT procedure is triggered, a timer is started with a scaled (e.g., timer value is multiplied or increased) value. The scaling factor can be indicated to the first device 110 in a dedicated manner (e.g., when the second device 120 sends the first device 110 to an inactive state) or through a system information broadcast.

[0103] UAC handling of SDT process

[0104] In order to support access barring check for cell reselection during the SDT procedure, another idea of ​​the present application is to perform access control before accessing a new cell.

[0105] Specifically, the inventors of the present application have noticed that in conventional solutions, UAC is only checked at the beginning of the access process. Therefore, if a RAN2 (Radio Layer 2 and Radio Layer 3RR) solution is provided (which can define a solution to potentially recover lost data), the current UAC process does not work because UAC is only checked when data transmission is triggered, not during data transfer. Therefore, if cell reselection is triggered during the SDT process, UAC is not checked on the new cell. Then, the problem is that in some cases, access to the terminal device may need to be prohibited, but the terminal device will not be checked according to the current UAC process. Therefore, a UAC processing procedure is required during the SDT process for cell reselection.

[0106] It should be understood that cell reselection during the SDT process means that the cell reselection occurs before the SDT transmission is completed. SDT transmission completion refers to the completion of, for example, UL and / or DL ​​(subsequent) data transmission. In one example, the SDT transmission can be considered to be completed after explicit signaling from the network device to the terminal device. It should also be understood that SDT can be enabled using a configured grant and / or a message sent during a random access channel (RACH) process.

[0107] Figure 6 FIG. 4 shows a signaling flow for UAC processing in cell reselection during an SDT process according to some example embodiments of the present disclosure. Figure 1 Describe the signaling flow 600. The signaling flow 600 may involve such Figure 1 A first device 110 , a second device 120 , and a third device 130 are shown.

[0108] In signaling flow 600, a first device 110 in an inactive state is located in a cell (e.g., cell 103) of a network 120 and is served therein. For ease of discussion, the cell in which the first device 110 is currently served is sometimes referred to as a first cell. The first device 110 in an inactive state performs 602 a SDT session with a second device 120. In some examples, the first device 110 may send uplink small data to the second device 120. In some other examples, the first device 110 may receive downlink small data from the second device 120.

[0109] The first device 110 determines 604 whether a target cell reselection criterion is met, which may be caused by the mobility of the first device 110. Then, if it is determined that the target cell reselection criterion is met (e.g., due to the mobility of the first device 110), the first device 110 reselects 606 a new cell to move to (referred to as the second cell). The first device 110 performs 608 access control before accessing the second cell. In this way, when an SDT session is ongoing, access control (e.g., UAC) can be performed after the first device selects a new cell. At the same time, when access control is performed based on information obtained from the network device 130, better network control of UE access via the UAC process can be guaranteed. After performing the access prohibition check, if allowed, the first device can access 610 the third device 130 (e.g., a RACH process can be performed with the third device 130).

[0110] Details on how to perform access control at the first device 110 will be described in various embodiments below. There may be various ways to perform access control at the first device 110. In some example embodiments, the first device 110 may first obtain information about access control. In some example embodiments, the first device 110 may obtain SIB1 from the third device 130. In some examples, SIB1 may include UAC prohibition per public land mobile network (PLMN) list, universal UAC prohibition, and the like. In some other examples, the access stratum (AS) of the first device 110 may obtain access category information from the non-access stratum (NAS) in the first device 110. NAS refers to, for example, an upper layer, and AS refers to, for example, RRC.

[0111] For example, the access category may include access categories 0, 1, and 2, which respectively indicate whether it is an access attempt for mobile termination (MT) access, an emergency session, data, or signaling. In another example, the access category may represent an access priority. It should be understood that the access category may be defined in other similar ways and is not limited to the examples given above, that is, the scope of the present application is not limited in this respect.

[0112] In some example embodiments, the AS of the first device 110 may include information related to the cell reselection to the NAS of the first device 110. Based on the indication, the NAS may then request a new access barring check from the AS on the reselected cell. In such an example embodiment, the NAS may provide the AS with an access category for the first device 110, and the AS may perform access control based on the access category. In this way, the first device 110 may determine whether its access category is allowed based on the SIB1 obtained from the third network device 130. In some examples, if the current SDT is a data transmission with a low priority, the access of the first device 110 to the new cell may be prohibited. In another example, if the access category indicates that it is an emergency call, the access of the first device 110 to the new cell may be allowed.

[0113] Alternatively, in some other example embodiments, the AS of the first device 110 may inform the NAS of the first device 110 that an access barring (AB) recheck is required. Thus, the NAS may then request a new access barring check from the AS on the reselected cell and also provide an access category.

[0114] Additionally or alternatively, the AS of the first device 110 may inform the NAS of the first device 110 whether the retry of the access category is allowed or prohibited. In some examples, once the access category is allowed, the first device 110 is able to access the new cell of the third device 130, for example, via a conventional procedure such as a RACH procedure. Otherwise, if the access category is not allowed, the first device 110 will be prohibited and cannot access the new cell, so that the ongoing SDT transmission will not continue in the new cell.

[0115] In one example, the AS of the first device 110 may check the barring status based on the original request. The original request may correspond to a request for SDT transmission in the old cell before cell reselection. Therefore, the AS may not need to obtain information about the access category from the NAS. Instead, the AS may check whether access is allowed under the assumption that the access category has not changed since the original request for SDT transmission was initiated. In addition, in the event that access is barred in the new cell, the first device 110 may notify the NAS of the first device 110 of the SDT failure.

[0116] Alternatively, in one example, the AS of the first device 110 may check the barring status without involving the NAS, and re-initiate SDT transmission when access is allowed.

[0117] In some example embodiments, third device 130 (i.e., a device for the new cell) may send an indication as to whether access control is performed to first device 110. First device 110 may then determine whether to perform access control based on the indication from third device 130. In some examples, third device 130 may send the indication to first device 110 via broadcast or dedicated signaling.

[0118] In some example embodiments, access control for the reselected cell may be ignored and access reestablishment may be performed regardless of the access category. For example, the first device 110 may be configured to ignore access control (e.g., UAC) procedures and access the new cell after the new cell is reselected by the first device 110.

[0119] Alternatively, the NAS or AS can restart the SDT transmission. In one example, upon checking access control, and once the access category is allowed, the NAS or AS can restart the SDT transmission.

[0120] Therefore, by enabling the access control process during the ongoing SDT process, better network control can be ensured for the first device 110. The first device 110 can access the third device 130 only if allowed, otherwise, for example, based on the SIB1 information obtained from the third device 130, the first device 110 will be prohibited, so that data transmission will not continue in the new cell.

[0121] Example Method

[0122] Figure 7 FIG. 7 is a flow chart showing a method 700 implemented at a first device according to some embodiments of the present disclosure. For discussion purposes, reference will be made to Figure 1 The method 700 is described from the perspective of the first device 110 .

[0123] At block 710, a first device performs a session of small data transmission between the first device and the second device. The first device is in an inactive state and is served in a first cell of the second device. At block 720, the first device determines whether a potential cell reselection criterion is satisfied while the session of small data transmission is ongoing. At block 730, based on a determination that the potential cell reselection criterion is satisfied, first information indicating a cell reselection intention is sent to the second device.

[0124] In some example embodiments, the first information includes at least one of: an identification of a second cell to be reselected by the first device, an indication that potential cell reselection criteria are satisfied, and an indication of whether the first device prefers an inactive state or a connected state.

[0125] In some example embodiments, the method 700 further includes receiving, from the second device, second information for switching from the first cell to a second cell of the third device; and switching from the first cell to the second cell based on the second information.

[0126] In some example embodiments, receiving the second information includes receiving, from the second device, first control information instructing the first device to maintain an inactive state, and switching from the first cell to the second cell includes performing cell reselection from the first cell to the second cell while the first device remains in the inactive state.

[0127] In some example embodiments, receiving the second information includes receiving, from the second device, a security configuration to be used in communicating with the second cell.

[0128] In some example embodiments, receiving the second information includes receiving a suspension configuration from the second device, the suspension configuration being used to suspend a connection through which a session for small data transmission is sent, and method 700 further includes sending a resume request to a third device for resuming the session for small data transmission in the second cell.

[0129] In some example embodiments, receiving the second information includes receiving second control information for instructing the first device to transition from an inactive state to a connected state, and switching from the first cell to the second cell includes performing a state transition from the inactive state to the connected state, and performing a handover from the first cell to the second cell.

[0130] In some example embodiments, receiving the second control information includes receiving a message including the second control information and a handover command, the handover command indicating an identity of the second cell for handover.

[0131] In some example embodiments, method 700 further comprises sending an indication to the third device that a session for small data transmission is ongoing in the first cell.

[0132] In some example embodiments, sending the first information includes determining whether mobility during a small data transmission process is allowed, mobility during the small data transmission process indicating switching of the first device from the first cell while a small data transmission session is ongoing; and in response to a determination that mobility during the small data transmission process is allowed, sending the first information indicating a cell reselection intention.

[0133] In some example embodiments, determining whether mobility during a small data transmission process is allowed includes receiving configuration information associated with mobility during the small data transmission process from a second device, the configuration information including information related to at least one of the following: an indication of whether mobility during the small data transmission process is allowed for the first device, an indication of whether the second device supports mobility during the small data transmission process, at least one cell in which mobility during the small data transmission process is allowed, at least one device that allows mobility during the small data transmission process, an area in which mobility during the small data transmission process is supported, and an indication of whether the small data transmission process is limited to the first cell; and determining whether mobility during the small data transmission process is allowed based on the configuration information.

[0134] In some example embodiments, method 700 further includes receiving an indication from the second device whether the small data transmission is limited to the first cell; and performing the small data transmission in the second cell after switching to the second cell based on the indication indicating a determination that the small data transmission is not limited to the first cell.

[0135] Figure 8 FIG. 8 is a flowchart of a method 800 implemented at a second device according to some embodiments of the present disclosure. For discussion purposes, reference will be made to Figure 1 The method 800 is described from the perspective of the second device 120 .

[0136] At block 810, the second device performs a session of small data transmission between the first device and the second device. The first device is in an inactive state and is served in a first cell of the second device. At block 820, the second device receives first information indicating a cell reselection intention from the first device.

[0137] In some example embodiments, the first information includes at least one of: an identification of a second cell to be reselected by the first device, an indication that potential cell reselection criteria are satisfied, and an indication of whether the first device prefers an inactive state or a connected state.

[0138] In some example embodiments, the method 800 further includes sending, to the first device, second information for handing over the first device from the first cell to a second cell of the third device.

[0139] In some example embodiments, sending the second information includes sending, to the first device, first control information for instructing the first device to maintain an inactive state.

[0140] In some example embodiments, sending the second information includes sending, to the first device, a security configuration to be used in communicating with the second cell.

[0141] In some example embodiments, sending the second information includes sending a suspend configuration to the first device, the suspend configuration for suspending a connection over which the session for the small data transfer is sent.

[0142] In some example embodiments, sending the second information includes sending second control information for instructing the first device to transition from an inactive state to a connected state.

[0143] In some example embodiments, sending the second control information includes sending a message including the second control information and a handover command indicating an identity of the second cell for handover from the first cell to the second cell.

[0144] In some example embodiments, method 800 also includes sending configuration information associated with mobility during a small data transmission process to the first device, the configuration information including information related to at least one of: an indication of whether mobility during the small data transmission process is allowed for the first device, an indication of whether the second device supports mobility during the small data transmission process, at least one cell in which mobility during the small data transmission process is allowed, at least one device that allows mobility during the small data transmission process, an area in which mobility during the small data transmission process is supported, and an indication of whether the small data transmission process is limited to the first cell.

[0145] In some example embodiments, the method 800 further comprises sending an indication to the first device whether the small data transmission is limited to the first cell.

[0146] Fig. 9 FIG. 9 is a flowchart of a method 900 implemented at a third device according to some other embodiments of the present disclosure. For discussion purposes, reference will be made to Figure 1 The method 900 is described from the perspective of the third device 130 .

[0147] In block 910, the third device receives an indication from the first device whether a session for small data transmission is being performed between the first device and the second device in a first cell of the second device. In block 920, the third device receives data for the session for small data transmission from the second device based on a determination that the first device is switching from the first cell to the second cell of the third device. The data is sent to the second device while the first device is being served in the first cell.

[0148] In some example embodiments, receiving the indication comprises receiving a medium access control control element message or a radio resource control message comprising the indication from the first device.

[0149] In some example embodiments, the handover to the second cell is performed via cell reselection, and the method 900 further includes receiving a resume request from the first device for resuming the session for the small data transmission in the second cell.

[0150] Example Device

[0151] In some embodiments, a first device (e.g., first device 110) capable of performing any of the methods 700 may include a component for performing the corresponding steps of the method 700. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module.

[0152] In some embodiments, the first device includes a component for performing a session of small data transmission between the first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; a component for determining whether potential cell reselection criteria are met while the session of small data transmission is ongoing; and a component for sending first information indicating a cell reselection intention to the second device based on a determination that the potential cell reselection criteria are met.

[0153] In some example embodiments, the first information includes at least one of: an identification of a second cell to be reselected by the first apparatus, an indication that potential cell reselection criteria are satisfied, and an indication of whether the first apparatus prefers an inactive state or a connected state.

[0154] In some example embodiments, the first device further includes means for receiving second information for switching from the first cell to a second cell of the third device from the second device; and means for switching from the first cell to the second cell based on the second information.

[0155] In some example embodiments, the means for receiving the second information includes means for receiving, from the second apparatus, first control information for instructing the first apparatus to maintain an inactive state, and the means for switching from the first cell to the second cell includes means for performing cell reselection from the first cell to the second cell while the first apparatus remains in the inactive state.

[0156] In some example embodiments, means for receiving the second information comprises means for receiving, from the second apparatus, a security configuration to be used in communicating with the second cell.

[0157] In some example embodiments, the component for receiving the second information includes a component for receiving a suspension configuration from the second device, the suspension configuration being used to suspend a connection through which a session for small data transmission is sent, and the first device also includes a component for sending a resume request to a third device for resuming the session for small data transmission in the second cell.

[0158] In some example embodiments, the means for receiving the second information includes means for receiving second control information for instructing the first device to transition from an inactive state to a connected state, and the means for switching from the first cell to the second cell includes means for performing a state transition from the inactive state to the connected state, and means for performing a switching from the first cell to the second cell.

[0159] In some example embodiments, the means for receiving the second control information comprises means for receiving a message comprising the second control information and a handover command indicating an identity of the second cell for handover.

[0160] In some example embodiments, the first apparatus further comprises means for sending an indication to the third apparatus that a session for small data transmission is ongoing in the first cell.

[0161] In some example embodiments, the component for sending the first information includes a component for determining whether mobility during a small data transmission process is allowed, the mobility during the small data transmission process indicating switching of the first device from the first cell while a small data transmission session is ongoing; and a component for sending the first information indicating a cell reselection intention in response to a determination that mobility during the small data transmission process is allowed.

[0162] In some example embodiments, a component for determining whether mobility during a small data transmission process is allowed includes a component for receiving configuration information associated with mobility during the small data transmission process from a second device, the configuration information including information related to at least one of the following: an indication of whether mobility during the small data transmission process is allowed for the first device, an indication of whether the second device supports mobility during the small data transmission process, at least one cell in which mobility during the small data transmission process is allowed, at least one device that allows mobility during the small data transmission process, an area in which mobility during the small data transmission process is supported, and an indication of whether the small data transmission process is limited to the first cell; and a component for determining whether mobility during the small data transmission process is allowed based on the configuration information.

[0163] In some example embodiments, the first device further includes means for receiving an indication from the second device whether the small data transmission is limited to the first cell; and means for performing the small data transmission in the second cell after switching to the second cell based on a determination that the indication indicates that the small data transmission is not limited to the first cell.

[0164] In some embodiments, a second device (e.g., second device 120) capable of performing any of the methods 800 may include a component for performing the corresponding steps of the method 800. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module.

[0165] In some example embodiments, the second device includes: a component for performing a session for small data transfer between the first device and the second device, the first device being in an inactive state and being served in a first cell of the second device; and a component for receiving first information indicating a cell reselection intention from the first device.

[0166] In some example embodiments, the first information includes at least one of: an identification of a second cell to be reselected by the first apparatus, an indication that potential cell reselection criteria are satisfied, and an indication of whether the first apparatus prefers an inactive state or a connected state.

[0167] In some example embodiments, the second apparatus further comprises means for sending, to the first apparatus, second information for handing over the first apparatus from the first cell to the second cell of the third apparatus.

[0168] In some example embodiments, the means for transmitting the second information includes means for transmitting, to the first apparatus, first control information for instructing the first apparatus to maintain an inactive state.

[0169] In some example embodiments, the means for sending the second information includes means for sending, to the first apparatus, a security configuration to be used in communicating with the second cell.

[0170] In some example embodiments, the means for sending the second information includes means for sending a suspend configuration to the first apparatus, the suspend configuration for suspending a connection over which the session for the small data transfer is sent.

[0171] In some example embodiments, the means for transmitting the second information includes means for transmitting second control information for instructing the first apparatus to transition from the inactive state to the connected state.

[0172] In some example embodiments, the means for sending the second control information includes means for sending a message including the second control information and a handover command indicating an identity of the second cell for handover from the first cell to the second cell.

[0173] In some example embodiments, the second device also includes a component for sending configuration information associated with mobility during a small data transmission process to the first device, the configuration information including information related to at least one of the following: an indication of whether mobility during the small data transmission process for the first device is allowed, an indication of whether the second device supports mobility during the small data transmission process, at least one cell in which mobility during the small data transmission process is allowed, at least one device that allows mobility during the small data transmission process, an area in which mobility during the small data transmission process is supported, and an indication of whether the small data transmission process is limited to the first cell.

[0174] In some example embodiments, the second apparatus further comprises means for sending an indication to the first apparatus whether the small data transmission is limited to the first cell.

[0175] In some embodiments, a third device (e.g., third device 130) capable of performing any of method 900 may include a component for performing the corresponding steps of method 900. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module.

[0176] In some example embodiments, the third device includes: a component for receiving an indication of whether a session for small data transmission is being conducted between the first device and the second device in a first cell of the second device from the first device; and a component for receiving data of the session for small data transmission from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell.

[0177] In some example embodiments, means for receiving the indication comprises means for receiving a media access control control element message or a radio resource control message comprising the indication from the first apparatus.

[0178] In some example embodiments, the means for handing over to the second cell via cell reselection, and the third apparatus further comprises means for receiving a resume request from the first apparatus for resuming the session for the small data transmission in the second cell.

[0179] Example devices and computer-readable media

[0180] Fig.10 1 is a simplified block diagram of a device 1000 suitable for implementing an embodiment of the present disclosure. The device 1000 may be provided to implement a communication device, such as Figure 1The first device 110, the second device 120 or the third device 130 is shown. As shown in the figure, the device 1000 includes one or more processors 1010, one or more memories 1020 coupled to the processor 1010, and one or more communication modules 1040 coupled to the processor 1010.

[0181] The communication module 1040 is used for two-way communication. The communication module 1040 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary to communicate with other network elements.

[0182] Processor 1010 may be of any type suitable for the local technology network, and may include, as non-limiting examples, one or more of: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 1000 may have multiple processors, such as application specific integrated circuit chips that are time slaved to a clock synchronized with a main processor.

[0183] The memory 1020 may 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) 1024, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1022 and other volatile memories that do not persist during power outages.

[0184] Computer program 1030 includes computer executable instructions executed by associated processor 1010. Program 1030 may be stored in ROM 1024. Processor 1010 may perform any suitable actions and processes by loading program 1030 into RAM 1022.

[0185] The embodiments of the present disclosure may be implemented by the program 1030 so that the device 1000 may execute the reference Figures 2 to 5 Any process of the present disclosure discussed. The embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0186] In some embodiments, the program 1030 may be tangibly contained in a computer-readable medium, which may be included in the device 1000 (such as in the memory 1020) or in other storage devices accessible to the device 1000. The device 1000 may load the program 1030 from the computer-readable medium to the RAM 1022 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Fig.11 An example of a computer readable medium 1100 in the form of a CD or DVD is shown. The computer readable medium has a program 1030 stored thereon.

[0187] Generally, various embodiments of the present disclosure may be implemented using hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using 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, flow charts, or using some other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented using hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0188] 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, such as instructions included in a program module, which are executed in a device on a target real or virtual processor to perform the above referenced Figure 3-Figure 6 Methods 700-900 described. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or split between program modules as needed. The machine executable instructions of program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in both local and remote storage media.

[0189] The program code for executing the disclosed method can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code causes the function / operation specified in the flow chart and / or block diagram to be realized when executed by the processor or controller. The program code can be executed completely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or completely on a remote machine or server.

[0190] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0191] The 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, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. A more specific example of a computer readable storage medium will include an electrical connection with one or more wires, a portable computer floppy disk, 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0192] In addition, although the operations are described in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in order or performing all the operations shown to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but rather descriptions of features that may be specific to a particular embodiment. Certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0193] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: performing a session of small data transmission between the first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; determining whether a potential cell reselection criterion is satisfied when the small data transmission session is ongoing; sending, based on a determination that the potential cell reselection criteria are satisfied, first information indicating a cell reselection intention to the second device; as well as An indication is sent to a third device as to whether the small data transmission session is being conducted between the first device and the second device in the first cell of the second device, so that the third device receives data of the small data transmission session from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, and the data is sent to the second device while the first device is being served in the first cell.

2. The first device according to claim 1, wherein the first information comprises at least one of the following: an identity of a second cell to be reselected by the first device, an indication that the potential cell reselection criteria are met, and An indication of whether the first device prefers the inactive state or the connected state.

3. The first device according to claim 1, wherein the first device is further configured to: receiving, from the second device, second information for switching from the first cell to a second cell of a third device; and Handover from the first cell to the second cell is based on the second information.

4. The first device according to claim 3, wherein the first device is caused to receive the second information by: receiving, from the second device, first control information for instructing the first device to maintain the inactive state, and The first device is caused to switch from the first cell to the second cell by: While the first device remains in the inactive state, cell reselection from the first cell to the second cell is performed.

5. The first device of claim 4, wherein the first device is caused to receive the second information further by: A security configuration is received from the second device to be used in communications with the second cell.

6. The first device of claim 4, wherein the first device is caused to receive the second information by: receiving a suspend configuration from the second device, the suspend configuration for suspending a connection over which the session of the small data transfer is sent, and The first device is further configured to: A resumption request for resuming the session for the small data transmission in the second cell is sent to the third device.

7. The first device of claim 3, wherein the first device is caused to receive the second information by: receiving second control information for instructing the first device to transition from the inactive state to the connected state, and The first device is caused to switch from the first cell to the second cell by: performing a state transition from the inactive state to the connected state, and A handover is performed from the first cell to the second cell.

8. The first device according to claim 7, wherein the first device is caused to receive the second control information: A message including the second control information and a handover command is received, the handover command indicating an identifier of the second cell used for the handover.

9. The first device according to claim 6 or 7, wherein the first device is further configured to: An indication is sent to the third device that the session for the small data transmission is being performed in the first cell.

10. The first device of claim 1, wherein the first device is further configured to send the first information by: determining whether mobility during a small data transmission process is allowed, the mobility during the small data transmission process indicating a handover of the first device from the first cell while the session for the small data transmission is ongoing; and In response to a determination that the mobility during the small data transmission procedure is allowed, the first information indicating the cell reselection intention is transmitted.

11. The first device of claim 10, wherein the first device is caused to determine whether the mobility during the small data transmission process is allowed by: receiving, from the second device, configuration information associated with the mobility during the small data transmission procedure, the configuration information comprising information related to at least one of: an indication of whether the mobility during the small data transfer procedure is allowed for the first device, an indication of whether the second device supports the mobility during the small data transfer procedure, at least one cell in which said mobility during said small data transmission procedure is allowed, at least one device allowing said mobility during said small data transfer procedure, an area in which said mobility during said small data transfer procedure is supported, and an indication of whether the small data transmission process is limited to the first cell; and Whether the mobility during the small data transmission procedure is allowed is determined based on the configuration information.

12. The first device according to claim 1, wherein the first device is further caused to: receiving from the second device an indication of whether small data transmission is limited to the first cell; and According to the determination that the indication indicates that the small data transmission is not limited to the first cell, after switching to the second cell, the small data transmission is performed in the second cell.

13. A second device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to: performing a session of small data transmission between a first device and the second device, the first device being in an inactive state and being served in a first cell of the second device; receiving first information from the first device, the first information indicating a cell reselection intention of the first device to switch from the first cell to a second cell of a third device; as well as Data of the session of the small data transmission is sent to the third device, the data being sent to the second device while the first device is served in the first cell.

14. The second device according to claim 13, wherein the first information comprises at least one of the following: an identity of a second cell to be reselected by the first device, an indication that potential cell reselection criteria are met, and An indication of whether the first device prefers the inactive state or the connected state.

15. The second device according to claim 13, wherein the second device is further caused to: Second information for switching the first device from the first cell to a second cell of a third device is sent to the first device.

16. The second device according to claim 15, wherein the second device is caused to send the second information by: First control information for instructing the first device to maintain the inactive state is sent to the first device.

17. The second device of claim 16, wherein the second device is caused to further send the second information by: A security configuration is sent to the first device to be used in communications with the second cell.

18. The second device of claim 16, wherein the second device is caused to send the second information by: A suspend configuration is sent to the first device, the suspend configuration being used to suspend a connection through which the session of the small data transfer is sent.

19. The second device of claim 15, wherein the second device is caused to send the second information by: Second control information for instructing the first device to transition from the inactive state to a connected state is sent.

20. The second device according to claim 19, wherein the second device is caused to send the second control information: A message including the second control information and a handover command is sent, wherein the handover command indicates an identifier of the second cell for handover from the first cell to the second cell.

21. The second device according to claim 13, wherein the second device is further caused to: Sending configuration information associated with mobility during a small data transmission process to the first device, the configuration information comprising information related to at least one of the following: an indication of whether the mobility during the small data transfer procedure is allowed for the first device, an indication of whether the second device supports the mobility during the small data transfer procedure, at least one cell in which said mobility during said small data transmission procedure is allowed, at least one device allowing said mobility during said small data transfer procedure, an area in which said mobility during said small data transfer procedure is supported, and An indication of whether the small data transmission process is limited to the first cell.

22. The second device according to claim 13, wherein the second device is further caused to: An indication is sent to the first device as to whether small data transmission is limited to the first cell.

23. A third device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the third device to: receiving, from a first device, an indication of whether a session for small data transmission is ongoing between the first device and the second device in a first cell of the second device; as well as receiving data of the session of the small data transmission from the second device based on a determination that the first device is switched from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell, The first device determines whether a potential cell reselection criterion is met when the small data transmission session is ongoing; and based on the determination that the potential cell reselection criterion is met, sends first information indicating a cell reselection intention to the second device.

24. The third device according to claim 23, wherein the third device is caused to receive the indication by: A medium access control control element message or a radio resource control message including the indication is received from the first device.

25. The third device according to claim 23, wherein the first device switches to the second cell via cell reselection, and wherein the third device is further caused to: A resume request for resuming the session for the small data transmission in the second cell is received from the first device.

26. A method for communication, comprising: At a first device, performing a session for small data transmission between the first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; determining whether a potential cell reselection criterion is satisfied while the small data transmission session is ongoing; as well as sending, based on a determination that the potential cell reselection criteria are satisfied, first information indicating a cell reselection intention to the second device; as well as The first device sends an indication to the third device as to whether a small data transmission session is being conducted between the first device and the second device in the first cell of the second device, so that the third device receives data of the small data transmission session from the second device based on a determination that the first device switches from the first cell to the second cell of the third device, and the data is sent to the second device while the first device is being served in the first cell.

27. A method for communication, comprising: At a second device, performing a session for small data transfer between a first device and the second device, the first device being in an inactive state and being served in a first cell of the second device; as well as receiving first information from the first device, the first information indicating a cell reselection intention of the first device to switch from the first cell to a second cell of a third device; as well as Data of the session of the small data transmission is sent to the third device, the data being sent to the second device while the first device is served in the first cell.

28. A method for communication, comprising: receiving, at a third device, from a first device, an indication of whether a session for small data transmission is being conducted between the first device and the second device in a first cell of the second device; as well as receiving data of the session of the small data transmission from the second device based on a determination that the first device is switched from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell, The first device determines whether a potential cell reselection criterion is met when the small data transmission session is ongoing; and based on the determination that the potential cell reselection criterion is met, sends first information indicating a cell reselection intention to the second device.

29. A first device for communication, comprising: means for performing, at a first device, a session for a small data transfer between the first device and a second device, the first device being in an inactive state and being served in a first cell of the second device; means for determining whether a potential cell reselection criterion is satisfied while a session of transmission of said small data is ongoing; as well as means for sending first information indicating a cell reselection intention to the second device and sending an indication to a third device whether a session for a small data transfer is ongoing between the first device and the second device in a first cell of the second device based on a determination that a potential cell reselection criterion is met, wherein The indication causes the third device to receive data of a small data transfer session from the second device based on the determination of the potential cell of the third device being handed over by the first device from the first cell, the data being sent to the second device while the first device is served in the first cell.

30. A second device for communication, comprising: means for performing a session for a small data transfer between a first device and the second device at a second device, the first device being in an inactive state and being served in a first cell of the second device; means for receiving first information indicating a cell reselection intention from the first device, the first information indicating a reselection intention of the first device to switch from the first cell to a second cell of a third device; as well as means for sending data of the session of the small data transfer to the third device, the data being sent to the second device while the first device is served in the first cell.

31. A third device for communication, comprising: means for receiving, at a third device, from a first device, an indication of whether a session for small data transfer is ongoing between the first device and the second device in a first cell of the second device; as well as means for receiving data of the session of the small data transmission from the second device based on a determination that the first device is switched from the first cell to the second cell of the third device, the data being sent to the second device while the first device is being served in the first cell, The first device determines whether a potential cell reselection criterion is met when the small data transmission session is ongoing; and based on the determination that the potential cell reselection criterion is met, sends first information indicating a cell reselection intention to the second device.

32. A computer readable medium comprising program instructions for causing an apparatus to at least perform the method according to claim 26, 27 or 28.

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