Methods, apparatuses and computer programs

Abstract

The present disclosure relates to methods, apparatuses and computer programs. A method performed by a session management function is provided, the method comprising: determining that a number of protocol data unit, PDU, sessions associated with a network slice has reached a threshold value; sending, based on the determination that the number of PDU sessions associated with the network slice has reached the threshold value, a message to a mobility management function for causing one or more first PDU sessions associated with the network slice to be released; receiving, from the mobility management function, a request to establish one or more third PDU sessions associated with the network slice; sending, to the mobility management function, a response message rejecting the request, the response message indicating a rejection cause and information indicating a second timer value; receiving, from the mobility management function, a request to re-establish the one or more first PDU sessions based on the first timer value and / or receiving, from the mobility management function, a request to re-establish the one or more third PDU sessions again based on the second timer value.

Description

Technical Field

[0001] Various examples of this disclosure relate to methods, apparatus, systems, and computer programs, particularly but not limited to protocol data unit session management. Background Technology

[0002] A communication network can be viewed as a facility that enables communication between two or more communication devices, or provides communication devices with access to a data network. Mobile or wireless communication networks are an example of communication networks. Communication devices may be served by application servers.

[0003] Such communication networks operate according to standards provided by, for example, 3GPP (3rd Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards provided by 3GPP are the so-called 3GPP standards used for various generations of cellular technologies, such as the 3GPP standards for 4G technology and the 3GPP standards for 5G technology. Summary of the Invention

[0004] Examples of this disclosure will be described with reference to certain aspects. These aspects are not intended to indicate key or essential features of the various examples of this disclosure, nor are they intended to limit its scope. In view of this disclosure, those skilled in the art will be able to understand other features, aspects, and elements. For example, it should be understood that other aspects can be provided by combination of any two or more aspects described below.

[0005] According to a first aspect, a method executed by a session management function is provided, the method comprising: determining that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; based on determining that the number of PDU sessions associated with the network slice has reached the threshold, sending a message to a mobility management function for releasing one or more first PDU sessions associated with the network slice, wherein the message for releasing one or more first PDU sessions associated with the network slice includes information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested, wherein the released One or more first PDU sessions are determined based on priority information, which indicates the priority of the PDU sessions associated with the network slice; a request is received from the mobility management function to establish one or more third PDU sessions associated with the network slice; a response message for the rejection request is sent to the mobility management function, the response message indicating: a reason for rejection and a second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating information that, after a second time period, the establishment of one or more third PDU sessions associated with the network slice can be requested again; and a request to re-establish one or more first PDU sessions is received from the mobility management function based on the first timer value; and / or a request to re-establish one or more third PDU sessions is received from the mobility management function based on the second timer value.

[0006] Network slices can be subject to network slice admission control.

[0007] Determining that the number of PDU sessions associated with a network slice has reached a threshold may include receiving information from the network slice admission control function indicating that the number of PDU sessions associated with a network slice has reached a threshold.

[0008] The method may further include: receiving a request from a mobility management function to establish one or more second PDU sessions associated with a network slice; and establishing one or more second PDU sessions associated with a network slice; wherein sending a message for causing one or more first PDU sessions associated with a network slice to be released is based on the indicated priority of the one or more second PDU sessions being higher than the indicated priority of the one or more first PDU sessions.

[0009] Priority information may include: allocation and reservation priority information and / or network slice admission control priority information.

[0010] The message used to cause one or more first PDU sessions to be released may include a list of candidate PDU sessions to be released and / or a threshold priority value used to determine which PDU sessions will be released.

[0011] The method may also include receiving information from the mobility management function that identifies one or more first PDU sessions that have been released.

[0012] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0013] The first timer value and / or the second timer value may depend on the relative priority between re-establishing one or more first PDU sessions and establishing one or more third PDU sessions.

[0014] According to a second aspect, a method performed by a mobility management function is provided, the method comprising: receiving from a session management function a message for releasing one or more first PDU sessions associated with a network slice, wherein the message for releasing one or more first PDU sessions associated with the network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; sending to at least one access node another message for releasing one or more first PDU sessions associated with the network slice, wherein the other message for releasing one or more first PDU sessions associated with the network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached; and receiving a request from at least one access node. The system initiates the following steps: 1. Establishing one or more third PDU sessions associated with a network slice; 2. Sending a request to a session management function to establish one or more third PDU sessions associated with a network slice; 3. Receiving a response message from the session management function indicating a rejection request and information indicating a second timer value, the response message indicating that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again; 4. Sending a response message to at least one access node indicating the reason for rejection and information indicating a second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; 5. Receiving a request from at least one access node to re-establish one or more first PDU sessions based on a first timer value, and / or receiving a request from at least one access node to re-establish one or more third PDU sessions based on a second timer value; 6. Sending a request to the session management function to re-establish one or more first PDU sessions based on the first timer value, and / or sending a request to the session management function to re-establish one or more third PDU sessions based on the second timer value.

[0015] Network slices can be subject to network slice admission control.

[0016] The message used to release one or more first PDU sessions and another message used to release one or more first PDU sessions may also include: a list of candidate PDU sessions to be released and / or a threshold priority value for determining which PDU sessions will be released.

[0017] The method may further include: receiving information from the access node indicating that one or more first PDU sessions have been released; and sending information to the session management function indicating that one or more first PDU sessions have been released.

[0018] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0019] According to a third aspect, a method executed by an access node is provided, the method comprising: receiving from a mobility management function a message for releasing one or more first PDU sessions, wherein the message for releasing one or more first PDU sessions includes: information indicating one or more first PDU sessions and information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; releasing one or more first PDU sessions based on the received message; receiving a request to establish one or more third PDU sessions associated with the network slice; sending a request to the mobility management function to establish one or more third PDU sessions associated with the network slice; and receiving from the mobility management function a response message of a rejection request and The system includes: information indicating a second timer value; a response message indicating that the reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached; the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; sending a response message to the first user equipment indicating a rejection request; the response message indicating the reason for rejection and information indicating the second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; receiving a request from the first user equipment to re-establish one or more first PDU sessions based on the first timer value, and / or receiving a request from the first user equipment to re-establish one or more third PDU sessions based on the second timer value; and sending a request to the mobility management function to re-establish one or more first PDU sessions based on the first timer value, and / or sending a request to the mobility management function to re-establish one or more third PDU sessions based on the second timer value.

[0020] Network slices can be subject to network slice admission control.

[0021] The message used to release one or more first PDU sessions may further include: a list of candidate PDU sessions to be released and / or a threshold priority value for determining which PDU sessions will be released, and the method may further include: determining one or more first PDU sessions to be released based on the list of candidate PDU sessions to be released and / or the threshold priority value.

[0022] The method may also include sending information to the mobility management function that identifies one or more PDU sessions that have been released.

[0023] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0024] According to a fourth aspect, a method performed by a user equipment is provided, the method comprising: receiving a request from an access node to release one or more first Protocol Data Unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; sending a request to the access node to establish one or more third PDU sessions associated with the network slice; and receiving a rejection request from the access node for one or more third PDU sessions. A response to the establishment of a third PDU session, wherein the response includes: information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with a network slice can be requested again; and sending a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or sending a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0025] At least one of the following can be sent to the access node based on a first timer value and a second timer value: sending a request to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions, based on the first timer value and the second timer value being the same, and based on the priority associated with one or more first PDU sessions and the priority associated with one or more third PDU sessions, before or after sending the request to re-establish one or more third PDU sessions to the access node.

[0026] The priority associated with one or more first PDU sessions may include the priority associated with a first application associated with one or more first PDU sessions, and the priority associated with one or more third PDU sessions may include the priority associated with a second application associated with one or more third PDU sessions.

[0027] At least one of the following can be included: sending a request to the access node to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions based on a first timer value and a priority associated with one or more first PDU sessions, wherein the first local timer value is determined based on the first timer value; and sending a request to the access node to re-establish one or more third PDU sessions based on a second local timer value and a priority associated with one or more third PDU sessions, wherein the second local timer value is determined based on the second timer value.

[0028] The priority associated with one or more first PDU sessions can be derived based on the latency criticality or latency budget of one or more applications associated with one or more first PDU sessions; and the priority associated with one or more third PDU sessions can be derived based on the latency criticality or latency budget of one or more applications associated with one or more third PDU sessions.

[0029] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0030] According to a fifth aspect, an apparatus for a first network function is provided, the apparatus comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network function to perform any of the methods of the first aspect.

[0031] According to a sixth aspect, an apparatus for a second network function is provided, the apparatus comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the second network function to perform any of the methods of the second aspect.

[0032] According to the seventh aspect, an access node is provided, the access node including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the access node to perform any method of the third aspect.

[0033] According to the eighth aspect, a user equipment is provided, the user equipment including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment to perform any method of the fourth aspect.

[0034] According to a ninth aspect, an apparatus for a first network function is provided, the apparatus comprising: components for determining that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; and components for sending a message to a mobility management function, based on the determination that the number of PDU sessions associated with the network slice has reached the threshold, to cause one or more first PDU sessions associated with the network slice to be released, wherein the message to cause one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested, wherein the one or more first PDU sessions to be released... The first PDU session is determined based on priority information, which indicates the priority of the PDU session associated with the network slice; components for receiving a request from the mobility management function to establish one or more third PDU sessions associated with the network slice; components for sending a response message to the mobility management function to reject the request, the response message indicating the reason for rejection and information indicating a second timer value, the reason for rejection being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; components for receiving a request from the mobility management function to re-establish one or more first PDU sessions based on a first timer value; and / or components for receiving a request from the mobility management function to re-establish one or more third PDU sessions based on a second timer value.

[0035] Network slices can be subject to network slice admission control.

[0036] Determining that the number of PDU sessions associated with a network slice has reached a threshold may include receiving information from the network slice admission control function indicating that the number of PDU sessions associated with a network slice has reached a threshold.

[0037] The apparatus may further include: a component for receiving a request from a mobility management function to establish one or more second PDU sessions associated with a network slice; and a component for establishing one or more second PDU sessions associated with a network slice; wherein sending a message for causing one or more first PDU sessions associated with a network slice to be released is based on an indicated priority associated with one or more second PDU sessions being higher than an indicated priority associated with one or more first PDU sessions.

[0038] Priority information may include: allocation and reservation priority information and / or network slice admission control priority information.

[0039] The message used to cause one or more first PDU sessions to be released may include: a list of candidate PDU sessions to be released and / or a threshold priority value used to determine which PDU sessions will be released.

[0040] The device may also include a component for receiving information from the mobility management function that identifies one or more first PDU sessions that have been released.

[0041] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0042] The first timer value and / or the second timer value may depend on the relative priority between re-establishing one or more first PDU sessions and establishing one or more third PDU sessions.

[0043] According to a tenth aspect, an apparatus for a mobility management function is provided, the apparatus comprising: a component for receiving from a session management function a message for releasing one or more first PDU sessions associated with a network slice, wherein the message for releasing one or more first PDU sessions associated with a network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for sending to at least one access node another message for releasing one or more first PDU sessions associated with a network slice, wherein the other message for releasing one or more first PDU sessions associated with a network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached; and a component for receiving a request from at least one access node to establish a connection with the network slice. The system comprises: one or more third PDU sessions associated with a network slice; a component for sending a request to a session management function to establish one or more third PDU sessions associated with the network slice; a component for receiving a response message of a rejection request from the session management function and information indicating a second timer value, the response message indicating that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again; a component for sending a response message of a rejection request to at least one access node, the response message indicating: the reason for rejection and information indicating the second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; a component for receiving a request to re-establish one or more first PDU sessions from at least one access node based on a first timer value, and / or receiving a request to re-establish one or more third PDU sessions from at least one access node based on a second timer value; and a component for sending a request to re-establish one or more first PDU sessions to the session management function based on a first timer value, and / or sending a request to re-establish one or more third PDU sessions to the session management function based on a second timer value.

[0044] Network slices can be subject to network slice admission control.

[0045] The message used to release one or more first PDU sessions and another message used to release one or more first PDU sessions may also include: a list of candidate PDU sessions to be released and / or a threshold priority value for determining which PDU sessions will be released.

[0046] The apparatus may further include: a component for receiving information from an access node that identifies one or more first PDU sessions that have been released; and a component for sending information that identifies one or more first PDU sessions that have been released to a session management function.

[0047] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0048] According to the eleventh aspect, an access node is provided, the access node comprising: a component for receiving from a mobility management function a message for releasing one or more first PDU sessions, wherein the message for releasing one or more first PDU sessions includes: information indicating one or more first PDU sessions, information for a reason for release, and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for releasing one or more first PDU sessions based on the received message; a component for receiving a request to establish one or more third PDU sessions associated with the network slice; a component for sending a request to the mobility management function to establish one or more third PDU sessions associated with the network slice; and a component for receiving a response message of a rejection request from the mobility management function. The system includes: a component for indicating a second timer value; a response message indicating that the reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached; the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; a component for sending a response message to the first user equipment to request a rejection, the response message indicating: the reason for rejection and the second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; a component for receiving a request from the first user equipment to re-establish one or more first PDU sessions based on a first timer value, and / or receiving a request from the first user equipment to re-establish one or more third PDU sessions based on a second timer value; and a component for sending a request to the mobility management function to re-establish one or more first PDU sessions based on a first timer value, and / or sending a request to the mobility management function to re-establish one or more third PDU sessions based on a second timer value.

[0049] Network slices can be subject to network slice admission control.

[0050] The message used to release one or more first PDU sessions may further include a list of candidate PDU sessions to be released and / or a threshold priority value for determining which PDU sessions will be released, and the method may further include: determining one or more first PDU sessions to be released based on the list of candidate PDU sessions to be released and / or the threshold priority value.

[0051] The access node may also include a component for sending information identifying one or more PDU sessions that have been released to the mobility management function.

[0052] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0053] According to a twelfth aspect, a user equipment is provided, the user equipment comprising: a component for receiving a request from an access node to release one or more first Protocol Data Unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for sending a request to the access node to establish one or more third PDU sessions associated with the network slice; and a component for receiving a rejection request from the access node for one or more third PDU sessions. A component for responding to the establishment of a PDU session, wherein the response includes information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and a component for sending a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or a component for sending a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0054] At least one of the following can be sent to the access node based on a first timer value and a second timer value: sending a request to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions, based on the first timer value and the second timer value being the same, and based on the priority associated with one or more first PDU sessions and the priority associated with one or more third PDU sessions, before or after sending the request to re-establish one or more third PDU sessions to the access node.

[0055] The priority associated with one or more first PDU sessions may include the priority associated with a first application associated with one or more first PDU sessions, and the priority associated with one or more third PDU sessions may include the priority associated with a second application associated with one or more third PDU sessions.

[0056] At least one of the following can be included: sending a request to the access node to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions based on a first timer value and a priority associated with one or more first PDU sessions, wherein the first local timer value is determined based on the first timer value; and sending a request to the access node to re-establish one or more third PDU sessions based on a second local timer value and a priority associated with one or more third PDU sessions, wherein the second local timer value is determined based on the second timer value.

[0057] The priority associated with one or more first PDU sessions can be derived based on the latency criticality or latency budget of one or more applications associated with one or more first PDU sessions; and the priority associated with one or more third PDU sessions can be derived based on the latency criticality or latency budget of one or more applications associated with one or more third PDU sessions.

[0058] The second timer value can be different from the first timer value, or the second timer value can be the same as the first timer value.

[0059] According to a thirteenth aspect, a computer-readable medium including instructions, which, when executed by a device, cause the device to perform the method according to any one of the first to fourth aspects, are provided.

[0060] According to the fourteenth aspect, a non-transitory computer-readable medium is provided, the non-transitory computer-readable medium including program instructions that, when executed by a device, cause the device to perform at least the method according to any one of the first to fourth aspects.

[0061] Many different aspects have been described above. As previously mentioned, it should be understood that other aspects can be provided by combining any two or more of the above aspects. Other features, aspects, and elements will become clear in light of the following. Attached Figure Description

[0062] Some examples will now be described with reference to the accompanying drawings (Figures), which are only non-limiting and illustrative examples, in which:

[0063] Figure 1 An example of a communication network to which the examples disclosed herein can be applied is shown;

[0064] Figure 2 This illustrates a representation of a fifth-generation communication system;

[0065] Figures 3-5The methods are shown based on some examples;

[0066] Figure 6 and Figure 7 The signaling process is illustrated based on some examples;

[0067] Figures 8 to 12 The methods shown are based on some examples; and

[0068] Figure 13 The apparatus is shown according to some examples. Detailed Implementation

[0069] Some examples of this disclosure can be implemented in communication networks, such as any of the following radio access technologies (RATs): WiMAX, GSM (2G), GSM EDGE Radio Access Network (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System based on Basic Wideband Code Division Multiple Access (W-CDMA) (UMTS, 3G), High-Speed ​​Packet Access (HSPA), LTE, LTE Advanced and Enhanced LTE (eLTE), 5G (also known as NR), or any future RAT, such as 6G. Furthermore, communication within the communication network can utilize any suitable 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), and / or Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM).

[0070] As used herein, the term "network device" or "network node" can refer to a node in a communication network through which user equipment can access the network and / or through which the node can control wireless communication and manage wireless resources within the cell. A network node or network device can be referred to as a base station (BS), access point (AP), or access node. Depending on the technology used, a network device can be, for example, a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), an NR NB (also known as a gNB), a Remote Radio Unit (RRU), a Radio Headend (RH), a Remote Radio Headend (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low-power node, a non-terrestrial network (NTN) or non-terrestrial network equipment (such as satellite network equipment, low Earth orbit (LEO) satellites, and geostationary orbit (GEO) satellites), or an airborne network equipment.

[0071] Furthermore, regarding the split architecture of the Radio Access Network (RAN), network devices can refer to the Centralized Unit (CU) and / or the Distributed Unit (DU) of a base station. The interface between the CU and DU can be referred to as the F1 interface in NR. In a split RAN architecture, node operations can be performed, at least partially coupled, to the central / centralized unit (CU) (e.g., server, host, or node) of the DU (e.g., radio head / node). A CU can control one or more DUs to at least act as a transmit / receive (Tx / Rx) node. In some examples, the DU may include, for example, the Radio Link Control (RLC), Media Access Control (MAC) layer, and Physical (PHY) layer, while the CU may include layers above the RLC layer, such as the Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC), and Internet Protocol (IP) layer. Other functional splits are also possible. In practice, any processing task can be performed in either the CU or the DU, and the boundary of responsibility between the CU and DU can depend on the applied implementation.

[0072] The term "terminal device" can refer to any terminal device capable of wireless communication. For example, a terminal device can be called a communication device, user equipment (UE), subscriber station (SS), or mobile station (MS). Terminal devices can include mobile phones, cellular phones, smartphones, VoIP phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, USB adapters, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), automobiles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc.

[0073] As used herein, the term "resource" can refer to radio resources in the time domain, frequency domain, spatial domain, and / or code domain. Some examples of resources include, for example, physical resource blocks (PRBs), radio frames, subframes, time slots, subbands, frequency regions, subcarriers, beams, etc. The terms "transmission" and / or "reception" can refer to wireless transmission and / or reception over radio resources via a radio propagation channel.

[0074] Figure 1The illustration shows an example of a communication network in which the examples disclosed herein can be applied. The communication network, or cellular communication network, may include network node 110 configured to provide one or more cells, such as cell 100, and network node 112 configured to provide one or more other cells, such as cell 102. For example, each cell may be a macrocell, microcell, femtocell, or picocell. A cell may define the coverage area or service area of ​​a corresponding access network node.

[0075] Network node 110 can be configured to provide radio access to a communication network to user equipment (UE) 120 (one or more UEs). Radio access may include downlink (DL) communication from the network node to UE 120 and uplink (UL) communication from UE 120 to the network node. Examples of uplink channels include a Physical Uplink Control Channel (PUCCH) for transmitting control information and a Physical Uplink Shared Channel (PUSCH) for transmitting data to the network. Examples of downlink channels include a Physical Downlink Control Channel (PDCCH) for transmitting control information and a Physical Downlink Shared Channel (PDSCH) for transmitting data to the user equipment.

[0076] Multiple UEs 120 and 122 can exist in this system. Each of the multiple UEs 120 and 122 can be served by the same or different network nodes 110 and 112. UEs can be configured with dual connectivity (DC), where a UE (e.g., UE 120) can connect to multiple network nodes 110 and 112. UEs 120 and 122 can communicate with each other when a device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). For example, such D2D communication can be referred to as machine-to-machine, peer-to-peer (P2P) communication, or vehicle-to-vehicle (V2V) communication.

[0077] In a communication network with multiple network nodes, these nodes can connect to each other via interfaces. The LTE specification refers to this interface as the X2 interface. The interface between an LTE node and a 5G node, or between two 5G nodes, can be called the Xn interface. Network nodes 110 and 112 can also connect to the core network 116 of the communication network via another interface.

[0078] The following examples are explained with reference to communication devices capable of communicating with a communication system. Before explaining the various examples of this disclosure in detail, please refer to… Figure 2 Briefly explain the fifth-generation communication system (5GS), its access network and core network (5GC), and communication equipment.

[0079] Figure 2 A schematic diagram of the communication system is shown. (Reference) Figure 2The illustration shows a user equipment (UE) 200 communicating via an application server (not shown) carrying third-party application functions (not shown) in a communication network and a data network 202. The communication network includes a radio access network 206 (e.g., a next-generation radio access network (NG-RAN)) and a core network 208 (e.g., a 5G core network (5GC)), which operate based on fifth-generation radio access technologies, such as those described in the 3rd Generation Partnership Project (3GPP) standard for new radio. The core network 208 includes network functions (generally referred to as network functions, collectively as network functions) that can be connected to a management system configured to manage the communication network, as described in further detail below.

[0080] The radio access network 206 includes one or more radio access network (RAN) nodes (also called base stations). RAN nodes can be configured to provide one or more cells. For example, a cell can be a macro cell, micro cell, femtocell, or picocell. A cell defines the coverage area or service area of ​​the RAN node. For example, a RAN node can be implemented as a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a next-generation Node B (gNB), a remote radio unit (RRU), a remote radio headend (RRH), a relay, an integrated access and backhaul (IAB) node, or a low-power node. RAN nodes can be deployed in non-terrestrial network (NTN) equipment, such as satellites (e.g., low Earth orbit (LEO) satellites or geostationary orbit (GEO) satellites), aircraft, or drones, where such NTN equipment forms a non-terrestrial network, such as a ground station. RAN nodes can also be deployed on the ground, in which case the RAN node can be referred to as a terrestrial network equipment. An RAN that includes terrestrial network equipment is generally referred to as a terrestrial network.

[0081] RAN nodes can have a split architecture, where the functionality of the RAN node (e.g., eNB or gNB) is distributed among various entities. A RAN node with a split architecture can include Radio Units (RUs) (also known as Remote Radio Headers (RRHs)), Centralized Units (CUs), and one or more Distributed Units (DUs). DUs can be connected to RUs via fronthaul links. DUs can be connected to CUs via midhaul or F1 interfaces. CUs can be connected to the core network (e.g., core network 208) via backhaul links (e.g., NG interfaces). In a RAN node with a split architecture, the operation of the RAN node can be performed by CUs and DUs. One CU can control one or more DUs.

[0082] The RU converts radio signals sent to and from the antenna into digital signals for transmission over a packet network, handles the digital front-end (DFE) and lower PHY layers, and includes digital beamforming capabilities. A DU is a logical entity (e.g., software) hosted on a server near the RU and running on that server. A CU is a logical entity hosted on a server and running on that server. A CU can be hosted on its own server and running on that server, or it can be hosted on the same server hosting and running the DU located near the RU and running on that server. A DU includes a subset of the RAN node's functionality (e.g., eNB or gNB), depending on the functionality breakdown, and a CU includes additional RAN node functionality not included in the DU's subset of functionality. A DU may include a subset of the layers of the RAN node's protocol stack, and a CU may include additional layers of the protocol stack not included in the DU's subset of layers. For example, in some implementations, the DU may include the Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer of the protocol stack for the RAN node, while the CU may include layers of the RAN node's protocol stack above the RLC layer, such as the Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Internet Protocol (IP) layer. The operation of the DU is controlled by the CU.

[0083] Core network 208 can have a service-based architecture. The network functions of core network 208 include Access and Mobility Function (AMF), Authentication Server Function (AUSF), Network Openness Function (NEF), Network Repository Function (NRF), Network Slice Selection Function (NSSF), Policy Control Function (PCF), Session Management Function (SMF), User Plane Function (UPF), Unified Data Repository (UDM), and Network Data Analysis Function (NWDAF). For ease of explanation, other network functions of core network 208 are described in... Figure 2 Not shown, such as Binding Support Function (BSF) and Billing Function (CHF).

[0084] AMF processes access, authorization, and authentication of user equipment (including UE 200), and manages the mobility of user equipment 200 when it moves between different radio access networks, cells, or locations.

[0085] The SMF is responsible for establishing, maintaining, and terminating Protocol Data Unit sessions in core network 208. The SMF manages user plane resources and interacts with the UPF in core network 208 to ensure that data packets are correctly routed and forwarded.

[0086] The UDM performs the authentication process, stores and manages user data, including subscriber profiles, authentication certificates, and authorization policies. The UDM implements security mechanisms to protect user data and resources of the communication network (e.g., core network 208) from unauthorized access attacks and vulnerabilities. Additionally, the UDM interacts with other network functions of core network 208 (such as PCF) to enforce access control policies, Quality of Service (QoS) parameters, and service restrictions based on user profiles and subscription plans. The UDM is also responsible for managing the registration of network functions serving user equipment 200.

[0087] The Network Data Analysis Function (NWDAF) is configured to collect or retrieve data about one or more network functions (NFs) in the core network, generate analyses based on the data collected or retrieved by the NWDAF about one or more NFs, and provide the generated analyses to itself or other NFs that have requested analyses generated by the NWDAF. The NWDAF may include an Analysis Logic Function (AnLF) configured to generate analyses (e.g., generate statistics and / or generate predictions) based on data collected and / or retrieved by the NWDAF about one or more NFs. The NWDAF also includes analysis services provided by the NWDAF to provide analyses generated by the AnLF. The NWDAF also includes a Model Training Logic Function (NWDAF (MTLF)) configured to train an AI / ML model, which can be used by the AnLF to generate analyses based on data collected or retrieved from one or more network functions and / or Orchestration and Management (OAM) entities.

[0088] For the sake of brevity, the functions of other network functions of core network 208 will not be described in detail.

[0089] Network slicing can be implemented in various network deployments, where virtualized, independent logical network slices can be implemented using common physical infrastructure. Each network slice can have its own set of network functions and its own specific service characteristics. Network slicing allows different slices to be customized to meet different requirements, and PDU sessions with specific requirements can be associated with network slices that can meet those requirements. For example, a PDU session for Ultra-Reliable Low-Latency Communication (URLLC) can be associated with a network slice customized for fast data speeds, while a PDU session for financial services can be associated with a network slice customized for enhanced security. A cell can support dozens or even hundreds of network slices, and according to 3GPP TS 38.300, a UE can be connected to up to eight network slices simultaneously.

[0090] Each network slice can be identified by Single Network Slice Selection Auxiliary Information (S-NSSAI). S-NSSAI can include a Slice Service Type (SST) field and a Slice Differentiator (SD) field. The SST field indicates the type of service provided by the slice and can have normalized or non-normalized values. For example, an SST value of 1 might indicate that the network slice is suitable for handling 5G Enhanced Mobile Broadband (eMBB), while an SST value of 2 might indicate that the network slice is suitable for handling URLLC, etc.

[0091] In some implementations, the number of PDU sessions associated with a given network slice (i.e., a given S-NSSAI) can be limited to a threshold or quota. In some examples, a network function (e.g., a network slice admission control function NSACF) can monitor the maximum number of PDU sessions that can be associated with a network slice. When an event triggers an increase in the number of PDU sessions associated with a network slice (e.g., a UE requesting to establish a new PDU session associated with the network slice, triggering an SMF request to establish a new PDU session with the network slice), the network function (e.g., NSACF) can check whether the number of PDU sessions associated with the network slice has reached the threshold or quota. The network function can then apply admission control to control the number of UEs registered to the network slice and / or the number of PDU sessions associated with the network slice, as described, for example, in 3GPP TS 23.501 V19.2.1.

[0092] For admission control purposes, each PDU session can be treated equally—that is, when thresholds or quotas are involved, each request to establish a PDU session associated with a specific network slice can be treated equally. This means that network slices can operate on a "first-come, first-served" basis, where PDU sessions are established for requests received before a threshold is reached, and any requests after the threshold is reached can be rejected.

[0093] Some PDU sessions can have higher priority or criticality than others. For example, priority can be indicated by parameters associated with a specific PDU session or QoS flow, such as Allocation Reservation Priority (ARP). However, when a threshold or quota for the total / maximum number of PDU sessions associated with a network slice is reached at the core network, any new PDU session establishment request for that network slice, including requests with high priority or higher priority than existing PDU sessions, can be rejected. This may lead to user dissatisfaction and potentially violate the service agreement.

[0094] Some examples described in this document can address one or more of these issues. Some examples enable the preemptive release of one or more PDU sessions when / if / based on a threshold or quota of PDU sessions associated with a network slice. The one or more PDU sessions to be released can be determined based on priority information indicating the priority of the PDU sessions associated with the network slice. For example, PDU sessions associated with low priority values ​​(i.e., priority values ​​below a certain threshold) can be identified for preemptive release. In this way, the network slice can preemptively release lower-priority PDU sessions while retaining the ability to accept requests for new PDU sessions with higher priority.

[0095] refer to Figure 3 It shows a method based on some examples. Figure 3 The method shown can be used for a first network function (such as SMF) / implemented at the first network function / executed by the first network function.

[0096] At point 300, the method includes determining that the number of PDU sessions associated with the network slice has reached a threshold.

[0097] At 302, the method includes: based on determining that the number of PDU sessions associated with the network slice has reached a threshold, sending a message to a second network function to release one or more first PDU sessions associated with the network slice. The message to release the one or more first PDU sessions associated with the network slice includes information indicating the reason for the release, which is that the one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established at the network slice being reached. The one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice.

[0098] refer to Figure 4 It shows a method based on some examples. Figure 4 The method shown can be used for a second network function (such as AMF) / implemented at the second network function / executed by the second network function.

[0099] At 400, the method includes: receiving from a first network function a message for causing one or more first PDU sessions associated with a network slice to be released.

[0100] At 402, the method includes sending another message to at least one access node to cause one or more first PDU sessions associated with the network slice to be released.

[0101] The message for causing one or more first PDU sessions associated with a network slice to be released and another message for causing one or more first PDU sessions associated with a network slice to be released include: information indicating one or more first PDU sessions and a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached.

[0102] refer to Figure 5 It shows a method based on some examples. Figure 5 The method shown can be used at access nodes (such as gNBs) / implemented at access nodes / executed by access nodes.

[0103] At 500, the method includes: receiving from a second network function a message for causing one or more first PDU sessions to be released, wherein the message for causing one or more first PDU sessions to be released includes: information indicating one or more first PDU sessions and a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached.

[0104] At 502, the method includes: releasing one or more first PDU sessions based on the received message.

[0105] In some examples, it is possible to implement information about network slices subject to Network Slice Admission Control (NSAC). Figures 3 to 5 The method described above. A first (network) entity can determine that the number of PDU sessions associated with a network slice has reached a threshold based on information received from a third network function indicating that the number of PDU sessions associated with the network slice has reached a threshold or quota. As previously mentioned, the third network function can be an NSACF.

[0106] In some examples, a UE may request the establishment of one or more second PDU sessions associated with a network slice. For instance, a UE may send a PDU session establishment request to a second network function via an access node, and the second network function may send a request to a first network function to establish one or more second PDU sessions.

[0107] Then, the first network function may accept the establishment of one or more second PDU sessions associated with the network slice, and cause one or more first PDU sessions associated with the network slice to be released. The one or more first PDU sessions may be released based on the indicated priority of the one or more second PDU sessions being higher than the indicated priority of the one or more first PDU sessions. That is, when the priority of one or more second PDU sessions is higher than the priority of one or more first PDU sessions, the first network function may release one or more first PDU sessions to facilitate the establishment of one or more second PDU sessions.

[0108] Priority information used to indicate the priority of the corresponding PDU session can include any suitable information, such as the ARP or NSAC priority information described above. NSAC priority information can be implemented internally by NSACF or can be configured to NSACF by OAM.

[0109] refer to Figure 6 It illustrates the signaling process based on some examples. Figure 6 In the example, the first network function is SMF, the second network function is AMF, the third network function is NSACF, and the access node is gNB. Prior to step 600, the network slice has one or more first PDU sessions established for UE2.

[0110] At point 600, the SMF determines that the number of PDU sessions associated with a network slice has reached a threshold or quota. For example, the SMF obtains information from the NSACF indicating that the threshold has been reached.

[0111] At position 602, UE1 sends a PDU session establishment request to the gNB. The gNB forwards the PDU session establishment request to the AMF, and then forwards it to the SMF. As mentioned earlier, the PDU session establishment request sent at position 602 includes a request to establish one or more second PDU sessions.

[0112] At position 604, the SMF can retrieve priority information related to the PDU session establishment request from the UDM. For example, the SMF can obtain ARP information associated with the PDU session establishment request.

[0113] At point 606, based on priority information indicating that one or more second PDU sessions have a higher priority than one or more first PDU sessions, the SMF determines that one or more first PDU sessions will be preemptively released.

[0114] At 608, the SMF sends a message to the AMF causing one or more first PDU sessions to be released. The AMF forwards this message to the gNB, and then further forwards it to UE2, as previously described. In some examples, the message sent to UE2 may be a NAS message sent from the AMF to the gNB and then from the gNB to UE2, or a message from the gNB itself.

[0115] At position 610, the SMF (via the AMF / gNB) sends a message to UE1 accepting the PDU session establishment request.

[0116] In some examples, the core network (e.g., a first network function and / or a second network function) can determine information for preemptively releasing one or more PDU sessions, and access nodes can use the determined information to determine the PDU(s) ...

[0117] The access node can then determine one or more first PDU sessions to be released based on a list of candidate PDU sessions to be released and / or a threshold priority value. For example, the access node can determine one or more candidate PDU sessions to be released (e.g., based on information stored at the access node, such as context information associated with the UE for which the candidate PDU sessions(s) were established, or based on a priority value associated with the PDU session being lower than a threshold).

[0118] refer to Figure 7 It illustrates the signaling process based on some examples. Figure 7 In the example, the first network function is SMF, the second network function is AMF, the third network function is NSACF, and the access node is gNB. Figure 7 In the example, the access node (i.e., gNB) determines the (multiple) PDU sessions to be released based on information received from the core network.

[0119] At point 700, the SMF determines that the number of PDU sessions associated with a network slice has reached a threshold. For example, the SMF obtains information from the NSACF indicating that the threshold has been reached.

[0120] At 702, the SMF determines a list of one or more candidate PDU sessions to be released and / or a threshold priority value, as previously described.

[0121] At position 704, the SMF sends a message to the AMF that causes one or more first PDU sessions to be released, and the AMF forwards the message to the gNB. The message that causes one or more first PDU sessions to be released includes a list of candidate PDU sessions to be released and / or a threshold, as previously described.

[0122] At 706, the gNB determines one or more first PDU sessions to be released based on the information received at 704, as previously described.

[0123] At 708, gNB releases one or more identified first PDU sessions.

[0124] At 710, the gNB sends information to the AMF identifying one or more PDU sessions that have been released, and the AMF forwards this information to the SMF.

[0125] Therefore, in some examples, the core network (e.g., the first network function) can determine the PDU sessions to be released, while in other examples, the access node can determine the PDU sessions to be released. In another example, both the core network and the access node can determine the PDU sessions to be released—for example, the first network function can determine certain PDU sessions to be released, and can also determine a threshold priority value, and send an indication of the threshold priority value along with information identifying the specific PDU session to be released to the access node.

[0126] In some examples, the access node may release one or more first PDU sessions based on an access node release procedure, such as as described in 3GPP TS 23.502. For example, the access node may send a request to the UE to release one or more first PDU sessions, and then remove the PDU sessions from the UE context, and also remove any radio-related resources associated with the PDU sessions at the access node.

[0127] In some examples, after one or more first PDU sessions have been released, the access node can send information identifying the released one or more PDU sessions to a second network function. The second network function can then forward this information to the first network function, allowing the first network function to know which PDU sessions associated with the network slice have been removed.

[0128] In some examples, the message used to cause one or more first PDU sessions to be released may include a first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with a network slice can be requested. A second network function may forward the first timer value to an access node in another message, and the access node may send the first timer value to one or more UEs when releasing one or more first PDU sessions.

[0129] Therefore, multiple UEs having one or more first PDU sessions that have been preemptively released can receive a first timer value from the access node or via the access node from the AMF. For example, multiple UEs can receive a request to release one or more first PDU sessions, the request including: information indicating the reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions have been preemptively released based on a threshold number of PDU sessions associated with a network slice. Multiple UEs can then request the re-establishment of one or more first PDU sessions based on the first timer value. For example, a UE can run a timer, and when the timer reaches the first timer value and a PDU session is still needed at the UE, the UE can request the re-establishment of one or more first PDU sessions.

[0130] In some examples, one or more UEs can request the establishment of one or more third PDU sessions associated with a network slice by sending a request to the access node to establish one or more third PDU sessions. The access node can forward the request(s) to a second network function(s), which in turn can forward the request(s) to a first network function(s).

[0131] A first network function can determine to reject one or more requests to establish a third PDU session(s) based on the fact that a threshold number of PDU sessions associated with a network slice has been reached. The first network function can send a response message to a second network function, rejecting the request(s) and indicating the reason for the rejection: the threshold number of PDU sessions associated with the network slice has been reached. The second network function can forward this response to an access node, which can then send a response message to one or more UEs rejecting the establishment of one or more third PDU sessions.

[0132] A response message that denies the establishment of one or more third PDU sessions may include information indicating a second timer value. The second timer value may indicate a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again. Multiple UEs can then re-request the establishment of one or more third PDU sessions based on the second timer value. For example, a UE may run a timer, and when the timer reaches the value of the second timer and a PDU session is still needed at the UE, the UE may request the establishment of one or more third PDU sessions.

[0133] In some examples, one or more first PDU sessions (preemptively released) and one or more third PDU sessions (with session establishment requests rejected) can be associated with different UEs.

[0134] In other examples, the same UE may have one or more first PDU sessions that have been preemptively released, and may have requests to establish one or more third PDU sessions that have been rejected. Figure 8 An example method executed by this UE is shown.

[0135] At 800, the method includes: receiving a request from an access node to release one or more first PDU sessions associated with a network slice, wherein the request includes: information indicating a reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested. In some examples, the request may be a NAS message sent from a second network function (e.g., AMF) to the access node and then from the access node to the UE. That is, at 800, the method may include: receiving a request from a second network function to release one or more first PDU sessions associated with the network slice.

[0136] At 802, the method includes sending a request to an access node to establish one or more third PDU sessions associated with a network slice. In some examples, the request may be a NAS message sent to the access node and then from the access node to a second network function (e.g., AMF). That is, at 802, the method may include sending a request to a second network function to establish one or more third PDU sessions associated with a network slice.

[0137] At 804, the method includes: receiving from an access node a response to refuse the establishment of one or more third PDU sessions, wherein the response includes information indicating the reason for refusing the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for refusing the establishment of one or more third PDU sessions associated with a network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again.

[0138] In some examples, the order of preemptively releasing one or more first PDU sessions and rejecting requests to establish one or more third PDU sessions can be changed. That is, in some examples, step 800 can be performed before steps 802 and 804 (e.g., Figure 9 As shown in the figure, in other examples, step 800 may be performed after steps 802 and 804.

[0139] At 806, the method includes sending at least one of the following to the access node based on a first timer value and a second timer value: a request to re-establish one or more first PDU sessions, and a request to re-establish one or more third PDU sessions.

[0140] The first timer value can differ from the second timer value. Depending on which timer value is shorter, the UE can request the re-establishment of (multiple) first PDU sessions or re-request the establishment of (multiple) third PDU sessions earlier. The first network function can set the first and second timer values ​​accordingly, depending on whether re-establishment or re-request is preferred (generally or for a specific (multiple) UE / PDU sessions).

[0141] In some examples, the UE may send a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or send a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0142] In some examples, the first timer value and the second timer value can be the same. In this case, based on the priority associated with one or more first PDU sessions and the priority associated with one or more third PDU sessions, the UE can send a request to re-establish one or more first PDU sessions before or after sending a request to the second network function to re-establish one or more third PDU sessions. That is, when the timer values ​​are the same (i.e., the network does not indicate which one to prioritize), the UE can determine whether to prioritize re-establishing (multiple) first PDU sessions or to re-request the establishment of (multiple) third PDU sessions.

[0143] The priority associated with one or more first PDU sessions may include the priority associated with a first application running at the UE. The priority associated with one or more third PDU sessions may include the priority associated with a second application running at the UE. The priority associated with one or more first / third PDU sessions may be derived based on the latency criticality or latency budget of the one or more applications associated with those first / third PDU sessions. For example, an application with higher latency criticality may have a higher priority than an application with lower latency criticality, or an application with lower latency budget may have a higher priority than an application with higher latency budget. Therefore, the UE may prioritize (re)establishing PDU sessions for applications with higher latency criticality / lower latency budget.

[0144] In some examples, the UE can determine a local timer associated with a first timer value and a second timer value, and send requests to re-establish one or more first PDU sessions and to re-establish one or more third PDU sessions based on the local timer. For example, the UE can send a request to the access node to re-establish one or more first PDU sessions based on a first local timer value and a priority associated with one or more first PDU sessions, the first local timer value being determined based on the first timer value; and send a request to the access node to re-establish one or more third PDU sessions based on a second local timer value and a priority associated with one or more third PDU sessions, the second local timer value being determined based on the second timer value.

[0145] refer to Figure 9 It shows a method based on some examples. Figure 9 The method shown can be used in SMF / implemented in SMF / executed by SMF.

[0146] At 900, the method includes: determining that the number of PDU sessions associated with the network slice has reached a threshold.

[0147] At 902, the method includes: based on determining that the number of PDU sessions associated with a network slice has reached a threshold, sending a message to a mobility management function to cause one or more first PDU sessions associated with the network slice to be released, wherein the message to cause one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested, wherein the one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice.

[0148] At 904, the method includes: receiving a request from a mobility management function to establish one or more third PDU sessions associated with a network slice.

[0149] At 906, the method includes: sending a response message of a rejection request to a mobility management function, the response message indicating: a reason for rejection and information indicating a second timer value, the reason for rejection being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again.

[0150] At 908, the method includes: receiving a request from the mobility management function to re-establish one or more first PDU sessions based on a first timer value; and / or receiving a request from the mobility management function to re-establish one or more third PDU sessions based on a second timer value.

[0151] refer to Figure 10A and Figure 10B It shows a method based on some examples. Figure 10A and Figure 10B The method shown can be used in the AMF / implemented in the AMF / executed by the AMF.

[0152] At 1000, the method includes: receiving from a session management function a message for causing one or more first PDU sessions associated with a network slice to be released, wherein the message for causing one or more first PDU sessions associated with a network slice to be released includes information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested.

[0153] At 1002, the method includes: sending to at least one access node another message for causing one or more first PDU sessions associated with a network slice to be released, wherein the other message for causing one or more first PDU sessions associated with a network slice to be released includes: information indicating one or more first PDU sessions and a reason for release and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached.

[0154] At 1004, the method includes: receiving a request from an access node to establish one or more third PDU sessions associated with a network slice.

[0155] At 1006, the method includes: sending a request to a first network function for session management to establish one or more third PDU sessions associated with a network slice.

[0156] At 1008, the method includes: receiving a response message of a rejection request from a first network function and information indicating a second timer value, the response message indicating that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, and the second timer value indicating a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again.

[0157] At 1010, the method includes: sending a response message of a rejection request to an access node, the response message indicating: a reason for rejection and information indicating a second timer value, the reason for rejection being that a threshold number of PDU sessions associated with the network slice has been reached.

[0158] At 1012, the method includes: receiving a request from the access node to re-establish one or more first PDU sessions based on a first timer value, and / or receiving a request from the access node to re-establish one or more third PDU sessions based on a second timer value.

[0159] At 1014, the method includes: sending a request to a session management first network function to re-establish one or more first PDU sessions based on a first timer value, and / or sending a request to a session management first network function to re-establish one or more third PDU sessions based on a second timer value.

[0160] refer to Figure 11A and Figure 11B It shows a method based on some examples. Figure 11A and Figure 11B The method shown can be used at the access node (e.g., gNB) / implemented at the access node / executed by the access node.

[0161] At 1100, the method includes: receiving from a mobility management function a message for releasing one or more first PDU sessions, wherein the message for releasing one or more first PDU sessions includes: information indicating one or more first PDU sessions and information for a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with a network slice can be requested.

[0162] At 1102, the method includes: releasing one or more first PDU sessions based on the received message.

[0163] At 1104, the method includes: receiving a request to establish one or more third PDU sessions associated with a network slice.

[0164] At 1106, the method includes: sending a request to a mobility management function to establish one or more third PDU sessions associated with a network slice.

[0165] At 1108, the method includes: receiving a response message of a rejection request from a mobility management function and information indicating a second timer value, the response message indicating that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, and the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again.

[0166] At 1110, the method includes: sending a response message of a rejection request to a first user equipment, the response message indicating: a reason for rejection and information indicating a second timer value, the reason for rejection being that a threshold number of PDU sessions associated with a network slice has been reached.

[0167] At 1112, the method includes: receiving a request from a first user equipment to re-establish one or more first PDU sessions based on a first timer value, and / or receiving a request from the first user equipment to re-establish one or more third PDU sessions based on a second timer value.

[0168] At 1114, the method includes: sending a request to the mobility management function to re-establish one or more first PDU sessions based on a first timer value, and / or sending a request to the mobility management function to re-establish one or more third PDU sessions based on a second timer value.

[0169] refer to Figure 12 It shows a method based on some examples. Figure 12 The method shown can be used by the UE / implemented at the UE / executed by the UE.

[0170] At 1200, the method includes: receiving a request from an access node to release one or more first PDU sessions associated with a network slice, wherein the request includes: information indicating the reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested.

[0171] At 1202, the method includes: sending a request to the access node to establish one or more third PDU sessions associated with the network slice.

[0172] At 1204, the method includes: receiving from an access node a response to reject the establishment of one or more third PDU sessions, wherein the response includes information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice being a threshold number of PDU sessions associated with the network slice that has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again.

[0173] At 1206, the method includes: sending a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or sending a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0174] In the examples described herein, various messages have been described, such as messages for causing one or more first PDU sessions associated with a network slice to be released, messages for requesting the establishment of one or more PDU sessions (e.g., one or more second PDU sessions or one or more third PDU sessions), and messages for refusing to establish one or more PDU sessions (e.g., one or more third PDU sessions). In some examples, at least some of these messages may include Non-Access Stratum (NAS) messages. That is, in some examples, messages for causing one or more first PDU sessions associated with a network slice to be released may include Non-Access Stratum (NAS) messages. For example, the AMF may send a NAS message to the access node for causing one or more first PDU sessions to be released, and the access node may forward the NAS message to the UE. In some examples, a request to establish one or more PDU sessions (e.g., one or more second PDU sessions and / or one or more third PDU sessions) may include a NAS message, which may be, for example, a NAS message sent from the UE to the access node, and the access node may forward the NAS message to the AMF. In some examples, messages for refusing to establish one or more PDU sessions (e.g., a response to refusing to establish one or more third PDU sessions) may include NAS messages. In other examples, the message may include messages other than NAS messages.

[0175] An example has been described in which one or more PDU sessions can be preemptively released based on the threshold number of PDU sessions associated with a network slice being reached. The one or more PDU sessions to be preemptively released can be based on priority information associated with the PDU session. This allows the network to accept requests for PDU sessions associated with the network slice that have a higher priority than the released PDU sessions(s).

[0176] While some examples have been described for specific network functions (such as AMF and SMF), it should be understood that the examples provided can be applied to other network functions that perform the same functions as those attributed to AMF, SMF, etc. For example, steps attributed to AMF in some of the examples described herein can also be performed by 6G Mobility Management (6G MM). Similarly, steps attributed to SMF in some of the examples described herein can be performed by 6G Session Management (6G SM).

[0177] In some examples, an apparatus for a first network function is provided, the apparatus comprising: means for determining that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; and means for sending a message to a second network function, based on the determination that the number of PDU sessions associated with the network slice has reached the threshold, to cause one or more first PDU sessions associated with the network slice to be released, wherein the message to cause one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for the release, the reason for the release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, wherein the one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice.

[0178] In some examples, an apparatus for a first network function is provided, the apparatus including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network function to at least: determine that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; and based on the determination that the number of PDU sessions associated with the network slice has reached the threshold, send a message to a second network function for causing one or more first PDU sessions associated with the network slice to be released, wherein the message for causing one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for the release, the reason for the release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, wherein the one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice.

[0179] In some examples, an apparatus for a second network function is provided, the apparatus comprising: a component for receiving from a first network function a message for releasing one or more first PDU sessions associated with a network slice; and a component for sending to at least one access node another message for releasing one or more first PDU sessions associated with a network slice, wherein the message for releasing one or more first PDU sessions associated with a network slice and the other message for releasing one or more first PDU sessions associated with a network slice include information indicating one or more first PDU sessions and a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached.

[0180] In some examples, an apparatus for a second network function is provided, the apparatus including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the second network function to at least: receive from a first network function a message for causing one or more first PDU sessions associated with a network slice to be released; and send to at least one access node another message for causing one or more first PDU sessions associated with a network slice to be released, wherein the message for causing one or more first PDU sessions associated with a network slice and the other message for causing one or more first PDU sessions associated with a network slice to be released include information indicating one or more first PDU sessions and information indicating a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established at the network slice being reached.

[0181] In some examples, an access node is provided, comprising: a component for receiving from a second network function a message for causing one or more first PDU sessions to be released, wherein the message for causing one or more first PDU sessions to be released includes information indicating one or more first PDU sessions and a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached; and a component for releasing one or more first PDU sessions based on the received message.

[0182] In some examples, an access node is provided, the access node including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the access node to at least: receive from a second network function a message for causing one or more first PDU sessions to be released, wherein the message for causing one or more first PDU sessions to be released includes: information indicating one or more first PDU sessions and a reason for release, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached; and release one or more first PDU sessions based on the received message.

[0183] In some examples, a user equipment is provided, comprising: a component for receiving a request from an access node to release one or more first Protocol Data Unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for release and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for sending a request to the access node to establish one or more third PDU sessions associated with the network slice; and a component for receiving a rejection or A component for responding to the establishment of multiple third PDU sessions, wherein the response includes: information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and a component for sending at least one of the following to the access node based on the first timer value and the second timer value: a request to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions.

[0184] In some examples, a user equipment is provided, comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment to at least: receive a request from an access node to release one or more first protocol data unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; and send a request to the access node to establish one or more sessions associated with the network slice. A third PDU session; receiving from the access node a response to refuse the establishment of one or more third PDU sessions, wherein the response includes: information indicating the reason for refusing the establishment of one or more third PDU sessions associated with the network slice and a second timer value, the reason for refusing the establishment of one or more third PDU sessions associated with the network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and sending to the access node at least one of the following based on the first timer value and the second timer value: a request to re-establish one or more first PDU sessions and a request to re-establish one or more third PDU sessions.

[0185] In some examples, an apparatus for a session management function is provided, the apparatus comprising: components for determining that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; and components for sending a message to a mobility management function, based on the determination that the number of PDU sessions associated with the network slice has reached the threshold, to cause one or more first PDU sessions associated with the network slice to be released, wherein the message to cause one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested, wherein the one or more first PDU sessions to be released... The PDU session is determined based on priority information, which indicates the priority of the PDU session associated with the network slice; components for receiving requests from the mobility management function to establish one or more third PDU sessions associated with the network slice; components for sending a response message to the mobility management function to reject the request, the response message indicating the reason for rejection and information indicating a second timer value, the reason for rejection being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; components for receiving requests from the mobility management second network function to re-establish one or more first PDU sessions based on a first timer value; and / or components for receiving requests from the mobility management second network function to re-establish one or more third PDU sessions based on a second timer value.

[0186] In some examples, an apparatus for a session management function is provided, the apparatus including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the session management function to at least: determine that the number of Protocol Data Unit (PDU) sessions associated with a network slice has reached a threshold; based on determining that the number of PDU sessions associated with the network slice has reached the threshold, send a message to a mobility management function to cause one or more first PDU sessions associated with the network slice to be released, wherein the message to cause one or more first PDU sessions associated with the network slice to be released includes information indicating a reason for release and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on the threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which one or more first PDUs associated with the network slice will be released. The re-establishment of a session can be requested, wherein one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice; a request is received from the mobility management function to establish one or more third PDU sessions associated with the network slice; a response message for the rejection request is sent to the mobility management function, the response message indicating: the reason for rejection and information indicating a second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and a request to re-establish one or more first PDU sessions is received from the mobility management second network function based on the first timer value; and / or a request to re-establish one or more third PDU sessions is received from the mobility management second network function based on the second timer value.

[0187] In some examples, an apparatus for a mobility management function is provided, the apparatus comprising: a component for receiving from a session management function a message for releasing one or more first PDU sessions associated with a network slice, wherein the message for releasing one or more first PDU sessions associated with a network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for sending to at least one access node another message for releasing one or more first PDU sessions associated with a network slice, wherein the other message for releasing one or more first PDU sessions associated with a network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached; and a component for receiving from at least one access node a request to establish a network slice associated with... The system includes: one or more third PDU sessions; a component for sending a request to a first network function of session management to establish one or more third PDU sessions associated with a network slice; a component for receiving a response message of a rejection request from the session management function and information indicating a second timer value, the response message indicating that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again; a component for sending a response message of a rejection request to at least one access node, the response message indicating: the reason for rejection and information indicating the second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; a component for receiving a request to re-establish one or more first PDU sessions from at least one access node based on a first timer value, and / or receiving a request to re-establish one or more third PDU sessions from at least one access node based on a second timer value; and a component for sending a request to the first network function of session management to re-establish one or more first PDU sessions based on a first timer value, and / or sending a request to the first network function of session management to re-establish one or more third PDU sessions based on a second timer value.

[0188] In some examples, an apparatus for a mobility management function is provided, the apparatus including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the mobility management function to at least: receive from a session management function a message for releasing one or more first PDU sessions associated with a network slice, wherein the message for releasing one or more first PDU sessions associated with the network slice includes: information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; and send to at least one access node another message for releasing one or more first PDU sessions associated with the network slice, wherein the other message for releasing one or more first PDU sessions associated with the network slice includes information indicating one or more first PDU sessions, a reason for release, and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached. The process involves: releasing the network slice; receiving a request from at least one access node to establish one or more third PDU sessions associated with the network slice; sending a request to a first network function for session management to establish one or more third PDU sessions associated with the network slice; receiving a response message from the session management function indicating a rejection request and information indicating a second timer value, wherein the response message indicates that the reason for rejection is that a threshold number of PDU sessions associated with the network slice has been reached, and the second timer value indicates a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again; and sending a response message to at least one access node to indicate a rejection request. The response message indicates: information for the reason for rejection and an indication of the second timer value, wherein the reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached; receiving a request to re-establish one or more first PDU sessions from at least one access node based on the first timer value, and / or receiving a request to re-establish one or more third PDU sessions from at least one access node based on the second timer value; and sending a request to re-establish one or more first PDU sessions to the session management first network function based on the first timer value, and / or sending a request to re-establish one or more third PDU sessions to the session management first network function based on the second timer value.

[0189] In some examples, an access node is provided, comprising: components for receiving from a mobility management function a message for releasing one or more first PDU sessions, wherein the message for releasing one or more first PDU sessions includes: information indicating one or more first PDU sessions, a reason for release, and information indicating a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; components for releasing one or more first PDU sessions based on the received message; components for receiving a request to establish one or more third PDU sessions associated with the network slice; components for sending a request to a second mobility management network function to establish one or more third PDU sessions associated with the network slice; and components for receiving a response message from the second mobility management network function indicating a rejection request and a first timer value. The components include: a component indicating a second timer value; a response message indicating that the reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached; the second timer value indicating a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again; a component for sending a response message to a first user equipment, the response message indicating: the reason for rejection and information indicating the second timer value, the reason for rejection being that the threshold number of PDU sessions associated with the network slice has been reached; a component for receiving a request from the first user equipment to re-establish one or more first PDU sessions based on a first timer value, and / or receiving a request from the first user equipment to re-establish one or more third PDU sessions based on a second timer value; and a component for sending a request to the Mobility Management Second Network Function to re-establish one or more first PDU sessions based on a first timer value, and / or sending a request to the Mobility Management Second Network Function to re-establish one or more third PDU sessions based on a second timer value.

[0190] In some examples, an access node is provided, comprising at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the access node to at least: receive from a mobility management function a message for releasing one or more first PDU sessions, wherein the message for releasing one or more first PDU sessions includes: information indicating one or more first PDU sessions and information indicating a reason for release and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with a network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; release one or more first PDU sessions based on the received message; receive a request to establish one or more third PDU sessions associated with the network slice; send a request to a second mobility management network function to establish one or more third PDU sessions associated with the network slice; and from the mobility management function... The second network function receives a response message for a rejection request and information indicating a second timer value. The response message indicates that the reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached. The second timer value indicates a second time period after which the re-establishment of one or more third PDU sessions associated with the network slice can be requested again. The second network function sends a response message for a rejection request to a first user equipment, indicating the reason for rejection and information indicating the second timer value. The reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached. The second network function receives a request from the first user equipment to re-establish one or more first PDU sessions based on the first timer value, and / or receives a request from the first user equipment to re-establish one or more third PDU sessions based on the second timer value. The second network function also sends a request to the mobility management second network function to re-establish one or more first PDU sessions based on the first timer value, and / or sends a request to the mobility management second network function to re-establish one or more third PDU sessions based on the second timer value.

[0191] In some examples, a user equipment is provided, comprising: a component for receiving a request from an access node to release one or more first Protocol Data Unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for release and a first timer value, the reason for release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; a component for sending a request to the access node to establish one or more third PDU sessions associated with the network slice; and a component for receiving a rejection request from the access node for one or more third PDU sessions. A component for responding to the establishment of a PDU session, wherein the response includes information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with a network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and a component for sending a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or a component for sending a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0192] In some examples, a user equipment is provided, the user equipment including at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment to at least: receive a request from an access node to release one or more first Protocol Data Unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating a reason for the release and a first timer value, the reason for the release being that one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of one or more first PDU sessions associated with the network slice can be requested; and send a request to the access node to establish one or more first PDU sessions associated with the network slice. The system receives a response from the access node rejecting the establishment of one or more third PDU sessions, wherein the response includes information indicating the reason for rejecting the establishment of one or more third PDU sessions associated with the network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with the network slice being that a threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and sends a request to the access node to re-establish one or more first PDU sessions based on a first timer value; and / or sends a request to the access node to re-establish one or more third PDU sessions based on a second timer value.

[0193] In some examples, a network device is provided that includes session management functions (e.g., SMF) and mobility management functions (e.g., AMF). A network device that includes network functions (e.g., session management functions, mobility management functions, SMF, or AMF) refers to a device / entity that performs at least a portion of the functions of a network function, or a device or entity configured to perform at least a portion of the functions of a network function. For example, the network device can perform methods performed by the AMF and SMF (e.g., Figure 3 and Figure 4 or Figure 9 , Figure 10A and Figure 10B (The method shown).

[0194] While references to “a,” “an,” or “some” examples may be made in this disclosure, this does not necessarily mean that the same example is referred to each time, nor does it necessarily mean that a particular feature applies only to a single example. Individual features from different examples may also be combined to provide other examples. Furthermore, when a particular feature, structure, or property is described in conjunction with examples, those skilled in the art can apply those features, structures, or properties in conjunction with other examples, whether or not explicitly described.

[0195] It should be understood that although the terms "first," "second," etc., may be used in this document to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0196] It should be understood that the references to various network functions (e.g., AMF, SMF, etc.) above can be implemented by means of devices performing at least some of the functions associated with these network functions. Furthermore, means configured to implement network functions can also be configured as virtual network function instances implementing those network functions. This means can be a virtual machine provided by the infrastructure of a cloud computing system (e.g., hypervisor, processor, and / or memory). This means can be part of a distributed computing system having multiple computing devices (e.g., servers) communicating with each other via a data network. Any part or all of the operation of a network function can be performed by the same means or different means, such as one or more computing devices in a distributed computing system.

[0197] It should be understood that these devices may include or be coupled to other units or modules, such as wireless components or wireless headends for transmission and / or reception. Although these devices are described as a single entity, different modules and memories may be implemented in one or more physical or logical entities.

[0198] It should be noted that while some examples have been described for 5G networks, similar examples can be applied to other networks and communication systems. Therefore, although some examples have been described above by way of example, with reference to certain example architectures of wireless networks, technologies, and standards in a non-limiting and illustrative manner, other examples can be applied to any other suitable form of communication system besides those shown and described herein.

[0199] It is also noted in this document that various changes and modifications may be made to the various examples described herein without departing from the scope of this disclosure.

[0200] As used herein, the phrases “at least one of A or B,” “at least one of A and B,” and “A and / or B” refer to (A), (B), or (A and B). For the purposes of this disclosure, the phrases “A, B, and / or C” refer to (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0201] As used herein, the term “or” means non-exclusive “or” unless otherwise stated (e.g., “otherwise” or “or in alternatives”).

[0202] As used herein, unless explicitly stated otherwise, “perform a step in response to A” does not mean that the step is performed immediately after “A” occurs, but may include one or more intermediate steps. Similarly, “perform a step or function based on A” does not mean that the step or function is performed solely based on “A”, as it may include one or more additional conditions.

[0203] Figure 13 A block diagram of apparatus 10 is shown by way of example. For example, apparatus 10 includes at least one processor 12 and at least one memory 14 storing instructions 15, which, when executed by the at least one processor, can cause apparatus 10 to perform at least one or more methods (or corresponding portions thereof) disclosed herein. In one example, at least one memory and instructions (e.g., computer program code, software) are configured, together with at least one processor, to cause apparatus 10 to perform one or more methods (or corresponding portions thereof) disclosed herein.

[0204] The processor 12 may include, or be configured as, one or more circuit systems configured to perform various stages of the methods described herein.

[0205] As used herein, the term “circuit system” can refer to one or more or all of the following: (a) a purely hardware circuit implementation, such as an implementation in an analog, digital and / or quantum circuit system; and (b) a combination of (multiple) hardware circuits and software, such as, where applicable: (i) a combination of (multiple) analog, digital or quantum hardware circuits with software / firmware; and (ii) any or all portions of (multiple) hardware processors (including (multiple) digital and / or quantum processors), software and (multiple) memories, which work together to enable a device (such as a mobile device, user device, computing device or server) to perform various functions; and (c) any or all portions of (multiple) hardware circuits, such as (multiple) microprocessors, (multiple) processors and / or (multiple) quantum processors, which require software (e.g., firmware) to operate, but may be absent when the software is not required to operate.

[0206] This definition of circuit system applies to all uses of the term in this disclosure, including in any claim. As another example, as used in this disclosure, the term circuit system also covers only hardware circuitry or a processor (or processors) or a portion of hardware circuitry or a processor and its accompanying software and / or firmware implementation. For example, if applicable to a particular claim, the term circuit system also covers baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or network devices.

[0207] The memory 14 can be implemented using any suitable data storage technology. The memory may include a database for storing data. The memory 14 may be at least partially located outside the device 10, but may be accessed by the device 10.

[0208] Instruction 15 may be included in a computer-readable medium or a non-transitory computer-readable medium. As used herein, the term “non-transitory” refers to a limitation on the medium itself (i.e., tangible, not tactile) rather than a limitation on the persistence of data storage (e.g., random access memory (RAM) versus read-only memory (ROM).

[0209] For example, device 10 can be implemented as a terminal device, such as the UE described above. As another example, the device can be included in such a terminal device, for example, as a chipset configured to control the terminal device. Device 10 can be made or configured to perform at least one or more of the methods described herein (or portions thereof).

[0210] As another example, device 10 can be implemented as an access node or network node, such as the access node or network node described above. In another example, the device can be included in such an access node or network node, for example, as a chipset configured to control an access node or network node. Device 10 can be made or configured to perform at least one or more of the methods described herein (or portions thereof).

[0211] The device may include one or more entities of any protocol layer, such as a MAC entity, RRC entity, RLC entity, PDCP entity, or PHY entity. In some examples, the entity may be configured to perform at least one or more methods from the examples described.

[0212] Device 10 may include a wireless interface 16. Wireless interface 16 may provide communication capabilities to device 10. Wireless interface 16 may include a receiver configured to receive information according to at least one cellular or non-cellular standard. Wireless interface 16 may include a transmitter configured to transmit information according to at least one cellular or non-cellular standard. Receivers may include more than one receiver. Transmitters may include more than one transmitter. Wireless interface 16 may include a transceiver configured to receive and transmit information according to at least one cellular or non-cellular standard. Transceivers may include more than one transceiver.

[0213] Device 10 may include an interface (e.g., a user interface) 18, which includes at least one of, for example, a keypad, a microphone, a touch display, a monitor, a speaker, etc. Interface 18 can be used to control the device (e.g., by a user). Interface 18 may be external to device 10. For example, device 10 may be connected to another device, such as a computer, via a wireless or wired connection, and device 10 may be controlled via the computer (e.g., by a user).

[0214] In some examples, at least some of the processes described herein can be performed by means including components for performing at least some of the processes. Components for performing the method steps disclosed herein may include software and / or hardware components of means 10. For example, at least one processor 12, memory 14, and computer program code form components for performing one or more methods disclosed herein, and any embodiments thereof. As used herein, the term “component” should be interpreted in the singular, i.e., meaning a single element; or in the plural, i.e., meaning a combination of single elements. Thus, the term “component for [performing A, B, C]” should be interpreted to encompass means in which only one component is used to perform A, B, and C, or means in which separate components are used to perform A, B, and C, or means in which partially or completely overlapping components are used to perform A, B, and C. Furthermore, the terms “component for performing A, component for performing B, and component for performing C” should be interpreted as covering an apparatus in which only one component is used to perform A, B, and C, or an apparatus in which a single component is used to perform A, B, and C, or an apparatus in which partially or completely overlapping components are used to perform A, B, and C.

[0215] The independent claims define the scope of protection sought by the various examples of this disclosure. Examples and features described in this disclosure that are not within the scope of the independent claims, and if any, shall be interpreted as examples that help to understand the various examples of this disclosure.

[0216] Although various examples have been described above with reference to the accompanying drawings, it is clear that these examples are not limited thereto and can be modified in many different ways. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate rather than limit these examples. As technology advances, those skilled in the art will understand how certain examples can be further implemented and / or modified in various ways. Furthermore, it will be apparent to those skilled in the art that the examples (or portions thereof) described herein can, but need not, be combined in various ways with any other examples (or portions thereof) described herein.

Claims

1. A method performed by a session management function, the method comprising: The number of Protocol Data Unit (PDU) sessions associated with the network slice has reached a threshold. Based on the determination that the number of PDU sessions associated with the network slice has reached the threshold, a message is sent to the mobility management function to release one or more first PDU sessions associated with the network slice. The message used to release the one or more first PDU sessions associated with the network slice includes information indicating a reason for release and information indicating a first timer value. The reason for release is that the one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions established with the network slice being reached. The first timer value indicates a first time period after which the re-establishment of the one or more first PDU sessions associated with the network slice can be requested. The one or more first PDU sessions to be released are determined based on priority information indicating the priority of the PDU sessions associated with the network slice. Receive a request from the mobility management function to establish one or more third PDU sessions associated with the network slice; Send a response message to the mobility management function to reject the request. The response message indicates: the reason for rejection and information indicating a second timer value. The reason for rejection is that the threshold number of PDU sessions associated with the network slice has been reached. The second timer value indicates a second time period after which the establishment of the one or more third PDU sessions associated with the network slice can be requested again. as well as Based on the first timer value, a request to re-establish the one or more first PDU sessions is received from the mobility management function; and / or Based on the second timer value, a request to re-establish the one or more third PDU sessions is received from the mobility management function.

2. The method of claim 1, wherein determining that the number of PDU sessions associated with the network slice has reached the threshold comprises: The network slice admission control function receives information indicating that the number of PDU sessions associated with the network slice has reached the threshold.

3. The method according to any one of the preceding claims further includes: Receive a request from the mobility management function to establish one or more second PDU sessions associated with the network slice; as well as Establish one or more second PDU sessions associated with the network slice; The message sent to cause the one or more first PDU sessions associated with the network slice to be released is based on the priority indicated for the one or more second PDU sessions being higher than the priority indicated for the one or more first PDU sessions.

4. The method according to claim 1, wherein the priority information includes allocation and retention priority information and / or network slice admission control priority information.

5. The method of claim 1, wherein the message for causing the one or more first PDU sessions to be released includes: A list of candidate PDU sessions to be released and / or a threshold priority value used to determine which PDU sessions will be released.

6. The method according to claim 5, further comprising: Receive information from the mobility management function identifying one or more first PDU sessions that have been released.

7. The method according to claim 1, wherein the second timer value is different from the first timer value, or the second timer value is the same as the first timer value.

8. The method of claim 1, wherein the first timer value and / or the second timer value depends on the relative priority between re-establishing the one or more first PDU sessions and establishing the one or more third PDU sessions.

9. A method performed by a user equipment, the method comprising: A request is received from the access node to release one or more first protocol data unit (PDU) sessions associated with a network slice, wherein the request includes: information indicating the reason for release and a first timer value, the reason for release being that the one or more first PDU sessions are preemptively released based on a threshold number of PDU sessions associated with the network slice being reached, the first timer value indicating a first time period after which the re-establishment of the one or more first PDU sessions associated with the network slice can be requested; Send a request to the access node to establish one or more third PDU sessions associated with the network slice; The access node receives a response rejecting the establishment of one or more third PDU sessions, wherein the response includes: information indicating a reason for rejecting the establishment of one or more third PDU sessions associated with the network slice and a second timer value, the reason for rejecting the establishment of one or more third PDU sessions associated with the network slice being that the threshold number of PDU sessions associated with the network slice has been reached, the second timer value indicating a second time period after which the establishment of one or more third PDU sessions associated with the network slice can be requested again; and Based on the first timer value, a request to re-establish the one or more first PDU sessions is sent to the access node; and / or Based on the second timer value, a request is sent to the access node to re-establish the one or more third PDU sessions.

10. The method of claim 9, wherein sending at least one of the requests to re-establish the one or more first PDU sessions and to re-establish the one or more third PDU sessions to the access node based on the first timer value and the second timer value comprises: Based on the fact that the first timer value and the second timer value are the same, and based on the priority associated with the one or more first PDU sessions and the priority associated with the one or more third PDU sessions, the request to re-establish the one or more first PDU sessions is sent before or after the request to re-establish the one or more third PDU sessions is sent to the access node function.

11. The method of claim 10, wherein the priority associated with the one or more first PDU sessions includes a priority associated with a first application associated with the one or more first PDU sessions, and the priority associated with the one or more third PDU sessions includes a priority associated with a second application associated with the one or more third PDU sessions.

12. The method of claim 9, wherein sending at least one of the requests to re-establish the one or more first PDU sessions and to re-establish the one or more third PDU sessions to the access node based on the first timer value and the second timer value comprises: Based on a first local timer value and the priority associated with the one or more first PDU sessions, a request to re-establish the one or more first PDU sessions is sent to the access node, wherein the first local timer value is determined based on the first timer value; as well as Based on a second local timer value and the priority associated with the one or more third PDU sessions, the request to re-establish the one or more third PDU sessions is sent to the access node, the second local timer value being determined based on the second timer value.

13. The method of claim 12, wherein the priority associated with the one or more first PDU sessions is derived based on the latency criticality or latency budget of one or more applications associated with the one or more first PDU sessions; and The priority associated with the one or more third PDU sessions is derived based on the latency criticality or latency budget of one or more applications associated with the one or more third PDU sessions.

14. The method of claim 9, wherein the second timer value is different from the first timer value, or the second timer value is the same as the first timer value.

15. An apparatus for communication, comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to perform the method according to claim 1 or 9.

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