CN113068237B

CN113068237B - Session management method, user equipment, computer storage medium and system

Info

Publication number: CN113068237B
Application number: CN202110335241.1A
Authority: CN
Inventors: 谢朝阳
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2022-08-16
Anticipated expiration: 2041-03-29
Also published as: CN115226176A; CN113068237A; WO2022206173A1

Abstract

The embodiment of the application discloses a session management method, user equipment, a computer storage medium and a system, which are applied to the user equipment, wherein the method comprises the following steps: receiving a Protocol Data Unit (PDU) session modification command; the PDU conversation modification command is used for indicating switching of the current first PDU conversation; and under the condition that the number of the established PDU sessions is detected to be smaller than a preset session threshold value, establishing a second PDU session and recording a monitoring result; wherein, the monitoring result at least comprises: establishing a second PDU session consumes time and carries out downlink user data traffic; and releasing the first PDU session according to the monitoring result. Therefore, the method not only can ensure the continuity of service stream transmission, but also can shorten the coexistence time of new and old sessions, avoid the waste of resources by user equipment and network equipment, and contribute to improving the system performance.

Description

Session management method, user equipment, computer storage medium and system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a session management method, a user equipment, a computer storage medium, and a system.

Background

With the rapid development of communication technology, Fifth Generation (5G) mobile communication technology is applied. In the 5G system, in order to ensure reliability of Data transmission, it is supported that multiple Protocol Data Unit (PDU) sessions can be created between a User Equipment (UE) and a network device. Here, the Service and Session Continuity (SSC) mode is an attribute of a PDU Session in the 5G system, and is used to indicate a guarantee mode of Service stream Continuity when the PDU Session performs Service transmission.

Currently, there are three values of the SSC pattern, which are SSC pattern 1, SSC pattern 2, and SSC pattern 3. When the network device decides to initiate the PDU session handover procedure of SSC mode 3, it means that the network side does not want to transmit the traffic stream through the PDU session and can release it at any time. However, due to the uncertainty of the specific implementation of the current handover process, the release strategies adopted by the current user equipment all have some defects, for example, either downlink service data being transmitted cannot be transmitted to the user, which causes interruption of service stream output; or the new session and the old session are kept simultaneously for a long time, which causes resource waste of both the user and the network and causes poor system performance.

Disclosure of Invention

The application provides a session management method, user equipment, a computer storage medium and a system, which not only can ensure the continuity of service stream transmission, but also can shorten the coexistence time of new and old sessions, avoid the waste of resources by the user equipment and network equipment, and are beneficial to improving the system performance.

In order to achieve the purpose, the technical scheme of the application is realized as follows:

in a first aspect, an embodiment of the present application provides a session management method, which is applied to a user equipment, and the method includes:

receiving a Protocol Data Unit (PDU) session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session; and

under the condition that the number of the established PDU sessions is smaller than a preset session threshold value, establishing a second PDU session and recording a monitoring result; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow;

and releasing the first PDU session according to the monitoring result.

In a second aspect, an embodiment of the present application provides a user equipment, where the user equipment includes a receiving unit, an establishing unit, and a releasing unit; wherein,

the receiving unit is configured to receive a Protocol Data Unit (PDU) session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session;

the establishing unit is configured to establish a second PDU session and record a monitoring result under the condition that the number of the established PDU sessions is smaller than a preset session threshold value; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow;

the release unit is configured to release the first PDU session according to the monitoring result.

In a third aspect, an embodiment of the present application provides a user equipment, including a memory and a processor; wherein,

the memory for storing a computer program operable on the processor;

the processor, when executing the computer program, is adapted to perform the method according to the first aspect.

In a fourth aspect, embodiments of the present application provide a computer storage medium storing a computer program, which when executed by at least one processor implements the method according to the first aspect.

In a fifth aspect, an embodiment of the present application provides a communication system, which includes a network device and a user equipment as described in the second aspect or the third aspect.

According to the session management method, the user equipment, the computer storage medium and the system provided by the embodiment of the application, a Protocol Data Unit (PDU) session modification command is received; wherein the PDU session modification command is used for indicating switching of the current first PDU session; and under the condition that the number of the established PDU sessions is detected to be smaller than a preset session threshold value, establishing a second PDU session and recording a monitoring result; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow; and releasing the first PDU session according to the monitoring result. Therefore, the technical scheme of the application adopts a mode that the user equipment uniformly initiates the release of the old PDU session, ensures the continuity of service flow transmission, and can also shorten the time for the new PDU session and the old PDU session to exist simultaneously, thereby avoiding the waste of resources by the user equipment and the network equipment, avoiding the risk of transmission interruption of user data, and being beneficial to improving the system performance.

Drawings

Fig. 1 is a schematic diagram of a relationship between a user equipment and a network device according to an embodiment of the present application;

fig. 2 is a schematic flowchart of a PDU session handover procedure in SSC mode 3 in a 5G network according to the related art;

fig. 3 is a flowchart illustrating a PDU session handover procedure of SSC mode 3 in another 5G network provided in the related art;

fig. 4 is a schematic flowchart of a session management method according to an embodiment of the present application;

fig. 5 is a schematic detailed flowchart of a session management method according to an embodiment of the present application;

fig. 6 is a detailed flowchart of another session management method according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a user equipment according to an embodiment of the present application;

fig. 8 is a schematic diagram of a specific hardware structure of a user equipment according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of a communication system according to an embodiment of the present application.

Detailed Description

So that the manner in which the features and elements of the present embodiments can be understood in detail, a more particular description of the embodiments, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of the present application only and is not intended to be limiting of the application.

In the following description, reference is made to "some embodiments" which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict. It should also be noted that reference to the terms "first \ second \ third" in the embodiments of the present application is only used for distinguishing similar objects and does not represent a specific ordering for the objects, and it should be understood that "first \ second \ third" may be interchanged with a specific order or sequence where possible so that the embodiments of the present application described herein can be implemented in an order other than that shown or described herein.

It should be noted that the Service and Session Continuity (SSC) mode is an attribute of a Protocol Data Unit (PDU) Session in the 5G system, and is used to indicate a guarantee mode of Service stream Continuity when the PDU Session performs Service transmission. In the Technical Specification (TS) 24.501 protocol of the third Generation Partnership Project (3 GPP), three values of the SSC mode are specified, namely SSC mode 1, SSC mode 2 and SSC mode 3. For a PDU Session with a value of SSC mode 1, its protocol data unit Session Anchor (PDU Session Anchor, PSA) does not change during the existence of the Session; for a PDU session with a value of SSC pattern 2, its PSA can be switched by first releasing the old session and then establishing a new session connected to the same Data Network (DN); for a PDU session with a value of SSC pattern 3, the PSA switches by first establishing a new session connected to the same DN and then deleting the old session, which may have a coexistence period.

The 3GPP TS 23.502 protocol specifies that during the PDU Session handover in SSC mode 3, the Session Management Function (SMF) on the network side may send a time-dependent parameter (generally referred to as "Session retention time") to the Session Management module (SM) on the user side. After receiving the parameter, the SM directly reports the parameter to an Application Processor (AP) of the user side, where the parameter is a time for the network side to notify the user side that the SMF of the network side is willing to reserve an old session for the user side in the current handover. For the PDU session handover in SSC mode 3, there are three scenarios in which the old session is released currently: (1) the network side carries session reservation time parameters, and in the session reservation time, the user side determines that all service data on the session are switched to a new session for transmission, and at the moment, the AP of the user side initiates a release process of the old session; (2) the network side carries the session retention time parameter, and after the session retention time is exceeded, the network side SMF directly initiates the release process of the old session; (3) the network side does not carry the session reservation time parameter, and the user side waits for the SMF of the network side to release the old session. In addition, it is explicitly indicated in the 3GPP TS 23.502 protocol how the user side traffic flow is switched from the old session to the new session, depending on the implementation of the user side itself.

It is understood that the relationship between the SM, AP and network side described above is specifically shown in fig. 1. In fig. 1, a network side has a network device, and a user side has a user device, where the user device includes an Application Processor (AP) and a session management module (SM); wherein, in the user equipment, the SM is set on a Modem (Modem).

Referring to fig. 2, a flowchart of a PDU session switching process of SSC mode 3 in a 5G network provided by the related art is shown. As shown in fig. 2, the process may include:

s201: and the network equipment and the AP transmit uplink/downlink data.

S202: the network device determines to switch the current old PDU session.

S203: the network device sends a PDU session modify command to the SM.

S204: the SM returns a PDU session modification completion command to the network device.

S205: the SM reports the first message to the AP.

S206: the AP issues a first message command to the SM.

S207: a new PDU session establishment procedure is performed between the SM and the network device.

S208: the SM reports the second message to the AP.

S209: and the user equipment switches the service flow from the old PDU session to the new PDU session according to the realization of the user equipment.

S210: and performing an old PCU session release flow between the AP and the network equipment.

Specifically, during the transmission of the uplink/downlink data between the user side and the network side, the network side determines, for some reason, the PSA corresponding to the PDU session where the current traffic flow is switched, and at this time, the network side performs internal processing, that is, performs step S202.

Subsequently, the network side may send a PDU session modification command, and the PDU session modification command may carry a session retention time parameter, that is, execute step S203; when receiving the PDU session modification command, the SM of the user side responds to the PDU session modification command, and reports the PDU session modification command to the AP of the user side, and if there is a session retention time parameter, reports the PDU session modification command to the AP, that is, executes steps S204 and S205. Here, the first message may be a message for modifying the current PDU session and carries a session reservation time.

Further, if the AP of the user side needs to judge whether the PDU session modification is in the SSC mode 3 after receiving the PDU session modification command, if so, then triggering the SM to initiate a PDU session establishment procedure; i.e., performing steps S206 and S207, the AP issues a first message command to the SM, the first message command being used to instruct the SM to establish a new PDU session.

Further, after the PDU session is successfully established, the user side switches the service flow from the old PDU session to the newly established PDU session according to the realization of the user side; that is, steps S208 and S209 are executed, after the PDU session is successfully established, the SM reports a second message to the AP, where the second message may be a message that the session is successfully established, and then the AP switches the service flow from the old PDU session to the new PDU session according to its own implementation method.

Further, during the transmission of the uplink/downlink data between the ue and the network device, the AP may release the old PDU session by one of the three PDU session release scenarios mentioned above according to whether the session retention time parameter is received, that is, execute step S210.

According to the flow shown in fig. 2, when the SMF on the network side decides to initiate the PDU session handover procedure of SSC mode 3, it means that the network side does not want to transmit the traffic stream through the PDU session and can release it at any time. Due to the uncertainty of the specific implementation of the switching process at the user side, for the purpose of ensuring that the service flow can be continuously transmitted, the network side can provide a period of time to maintain the existence of the new PDU session and the old PDU session (possibly informing the user side through the session retention time parameter or not), so that the user side has sufficient time to smoothly switch the service flow from the old PDU session to the new PDU session, and then the old PDU session is released through the PDU session release flow.

Currently, there are two general PDU session release strategies used by the user side: (1) if the user side receives the session retention time parameter, after the new PDU session is successfully established, the AP directly initiates the release process of the old PDU session; if the parameter is not received, waiting for the network side to initiate the release process of the old PDU session. (2) The user side waits for the network side to initiate the release process of the old PDU session regardless of whether the session reservation time parameter is received or not.

In a common scenario, the release policy adopted by the current user side has the following problems:

(a) the user side initiates the old PDU session release immediately after the new session is successfully established, and although the old PDU session resources of the user and the network can be rapidly released, a situation may occur, which causes the interruption of the service stream transmission. That is, when the network just transmits the downstream service data through the old PDU session, the network receives the release request sent by the user side at this time, and then releases the old PDU session, so that the downstream service data being transmitted cannot be transmitted to the user, and the service flow output is interrupted.

(b) The user side always waits for the network side to initiate the release process of the old PDU session, and although the situation that transmission is interrupted when the service flow is switched from the old PDU session to the new PDU session can be guaranteed, the new PDU session and the old PDU session are kept simultaneously for a long time, so that the situation that resources are wasted by both the user and the network occurs.

In addition, in a special scenario, the release strategy adopted by the current user side may cause a more serious problem. If the number of the PDU sessions established by the SM layer of the user side has reached the limit number of the user side, according to the description of the 3GPP TS 24.501 protocol, after the user receives the PDU session modification command sent by the network, since a new PDU session cannot be established, the request of the network is directly rejected, and the old PDU session is continuously used for transmission. At this time, there may be two corresponding processes on the network side: 1) terminating the switching process and continuing to use the current PDU session (namely the old PDU session) for transmission. But due to the handover, the old PDU session is already in saturation state at the PSA of the network side, and the continued use of the old PDU session may cause the transmission quality to be degraded. 2) After waiting for a period of time, the network directly initiates the release of the old PDU session. This would result in the traffic on the PDU session not being able to continue, against the original intention of trying to ensure that the PDU session traffic is continuous. For example, refer to fig. 3, which shows a flowchart of a PDU session handover procedure of SSC mode 3 in another 5G network provided by the related art. As shown in fig. 3, the process may include:

s301: and the network equipment and the AP transmit uplink/downlink data.

S302: the network device determines to switch the current old PDU session.

S303: the network device sends a PDU session modify command to the SM.

S304: when detecting that the number of the currently established sessions reaches a preset session threshold, the SM rejects the PDU session modification command.

S305: the SM returns a PDU session modification reject command to the network device.

S306: the network device continues to use or release the old PDU session.

Specifically, during the transmission of the uplink/downlink data between the user side and the network side, if the network decides to switch the current PDU session, the network side will initiate a PDU session modification procedure, i.e. execute steps S302 and S303.

On the user side, if the SM detects that the currently established PDU session has reached the preset session threshold (such as the maximum number of sessions supported by the user), the user side will reject the PDU session modification command of the network, i.e. execute step S304.

Further, the user returns the PDU session modification reject command to the network device, and after receiving the modification reject command on the network side, the old PDU session may be maintained at this time or released after a certain period of time, that is, steps S305 and S306 are executed.

In short, in the related art, due to the uncertainty of the specific implementation of the PDU switching process for the SSC mode 3, the release strategies adopted by the current user equipment all have some defects, for example, either downlink service data being transmitted cannot be transmitted to the user, which causes interruption of service stream output; or the new session and the old session are kept simultaneously for a long time, which causes resource waste of both the user and the network and causes poor system performance.

The embodiment of the application provides a session management method, which is applied to user equipment and has the following basic ideas: receiving a PDU session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session; and under the condition that the number of the established PDU sessions is detected to be smaller than a preset session threshold value, establishing a second PDU session and recording a monitoring result; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow; and releasing the first PDU session according to the monitoring result. Therefore, the technical scheme of the application adopts a mode that the user equipment uniformly initiates the release of the old PDU session, thereby ensuring the continuity of service flow transmission, shortening the time for the new PDU session and the old PDU session to exist simultaneously, avoiding the waste of resources by the user equipment and the network equipment, avoiding the risk of transmission interruption of user data and being beneficial to improving the system performance.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

In an embodiment of the present application, referring to fig. 4, a flowchart of a session management method provided in the embodiment of the present application is shown. As shown in fig. 4, the method may include:

s401: a PDU session modification command is received.

It should be noted that the session management method in the embodiment of the present application is applied to the user equipment. Here, the user equipment may also be referred to as a terminal equipment, and may be, for example, a smart phone, a tablet computer, a notebook computer, a palmtop computer, a Personal Digital Assistant (PDA), a Portable Media Player (PMP), a navigation device, a wearable device, a mobile station (mobile station), a mobile unit (mobile unit), a mobile client, a chip, a Field Programmable Gate Array (FPGA), and the like, which are not limited herein.

It should be noted that the PDU session modification command is used to indicate the current first PDU session is to be switched. Specifically, when the network device decides to switch the current first PDU session, the network device initiates a PDU session modification procedure at this time, and sends a PDU session modification command to the terminal device. That is, if the network device decides to switch the current first PDU session, the user equipment may receive a PDU session modification command sent by the network device.

In the embodiment of the present application, from the perspective of service stream continuity, after receiving a PDU session modification command, a user equipment may propose a corresponding optimization scheme for different application scenarios according to an application scenario and an actual situation of the user equipment itself to determine when the user equipment releases a first PDU session (i.e., an old PDU session), so as to ensure service stream transmission continuity as much as possible and save resources on a user side and a network side.

Specifically, according to the embodiment of the application, the application scenes can be divided into normal scenes and special scenes according to the comparison result of the number of established PDU sessions and the preset session threshold, and then optimization schemes are respectively provided for the two application scenes.

S402: and under the condition that the number of the established PDU sessions is detected to be less than a preset session threshold value, establishing a second PDU session and recording a monitoring result.

S403: and releasing the first PDU session according to the monitoring result.

Here, the monitoring result may include at least: the establishment of the second PDU session takes time and the downlink user data traffic.

It should be noted that the number of established PDU sessions refers to the number of PDU sessions that have been successfully established in the user equipment. Typically, the maximum number of sessions supported by the user equipment is 15, and the preset session threshold may be the maximum number of sessions supported by the user equipment. However, the preset session threshold may be specifically set according to actual situations, for example, the preset session threshold may be set to 15, and may also be set to 10, which is not limited herein.

It should be further noted that, the number of established PDU sessions is compared with a preset session threshold; if the number of established PDU sessions is less than the preset session threshold, indicating that the current application scenario is a normal scenario, the optimization scheme at this time is to execute steps S402 and S403. If the number of established PDU sessions is greater than or equal to the preset session threshold, indicating that the current application scenario is a special scenario, the optimization scheme at this time will be described as follows.

In some embodiments, after S401, the method may further include:

under the condition that the number of the established PDU sessions is detected to be larger than or equal to a preset session threshold value, releasing the first PDU session;

and after the first PDU session is successfully released, establishing a second PDU session.

That is, for a special scenario, after receiving the PDU session modification command, if it is detected that the number of established PDU sessions is greater than or equal to the preset session threshold, the ue will release the first PDU session first, and then establish the second PDU session after the first PDU session is successfully released.

Specifically, in a special scenario, if it is detected that the number of established PDU sessions is greater than or equal to the preset session threshold, at this time, process information, such as recording an identification information, may be recorded, and the first PDU session is released; and after the first PDU session is successfully released, establishing a second PDU session according to the identification information. The identification information here may indicate that, when it is detected that the number of established PDU sessions is greater than or equal to the preset session threshold, the release procedure of the first PDU session is triggered first, and then the establishment procedure of the second PDU session is started.

It should also be noted that the first PDU session may be referred to as an old PDU session, and the second PDU session may be referred to as a new PDU session. Further, in some embodiments, the method may further comprise: and carrying out data interaction through the second PDU session.

That is, after the second PDU session is successfully established, the network device and the user equipment may perform data interaction using the second PDU session.

It can be understood that, due to an attribute of the PDU session in the SSC mode 5G system, it can indicate a guarantee mode of service flow continuity when the PDU session carries out service transmission. Currently, in the 3GPP TS 24.501 protocol, three values of the SSC pattern are specified, namely, SSC pattern 1, SSC pattern 2, and SSC pattern 3. For a PDU session with a value of SSC pattern 1, its PSA does not change during the existence of the session; for a PDU session with a value of SSC pattern 2, its PSA can switch by first releasing the old session and then establishing a new session connected to the same DN; for a PDU session with a value of SSC pattern 3, the PSA switches by first establishing a new session connected to the same DN and then deleting the old session, which may have a coexistence period. That is, in SSC mode 3, the network device allows the PDU session between the ue and the old PDU session anchor to be maintained until the new PDU session (new PDU session anchor accesses the same DN) is established, and the ue has two session anchors and PDU sessions at the same time, and finally releases the old PDU session.

Based on this, in the SSC mode 3 type PDU session switching process, the network device does not want to transmit the service flow through the old PDU session, and can release it at any time; however, due to the uncertainty of the specific implementation of the user equipment in the PDU session handover process, for the purpose of ensuring that the service flow can be continuously transmitted, the embodiment of the present application mainly solves the problem of the release policy of the old PDU session in the SSC mode 3.

In a possible implementation manner, for a normal scenario, in a case that it is detected that the number of established PDU sessions is less than a preset session threshold, the method may further include:

determining a mode type of the first PDU session;

and when the mode type of the first PDU session is a preset mode type, executing the steps of establishing a second PDU session and recording a monitoring result.

In another possible implementation manner, for a special scenario, in a case that it is detected that the number of established PDU sessions is greater than or equal to a preset session threshold, the method may further include:

determining a mode type of the first PDU session;

and when the mode type of the first PDU session is a preset mode type, executing a step of releasing the first PDU session.

In the embodiment of the present application, the predetermined pattern type is SSC pattern 3.

That is, the user equipment needs to detect whether the SSC mode 3 type PDU session is currently switched or not after receiving the PDU session modification command, regardless of the normal scenario or the special scenario. In other words, if the mode type of the first PDU session to be currently switched is SSC mode 3, the release of the old PDU session can be performed according to the session management method described in the embodiment of the present application; if the mode type of the first PDU session to be currently switched is not SSC mode 3, the release of the old PDU session can be performed in a conventional session management manner.

Further, for a normal scenario, a problem caused when an existing release policy releases an old PDU session may be solved by initiating the release of the old PDU session by the user equipment. The embodiment of the application provides a method for switching service flows by user equipment to determine when to release a PDU session. Specifically, in some embodiments, the establishing a second PDU session and recording a monitoring result may include:

recording a first moment at the moment of establishing and starting the second PDU session;

monitoring whether the first PDU session receives downlink user data or not in the process of establishing the second PDU session;

recording a second moment at the moment when the second PDU session is successfully established;

calculating the time consumed for establishing the second PDU session according to the second time and the first time;

and taking the time consumed for establishing the second PDU session and the downlink user data flow as the monitoring result for recording.

It should be noted that, when it is detected that the switching of the SSC mode 3 type PDU session is currently performed, at this time, an establishment procedure of a second PDU session may be initiated, and at the time of initiating establishment of the second PDU session, a first time is recorded, and at the same time, it is detected whether the first PDU session currently being switched receives downlink user data; then, after the second PDU session is successfully established, a second moment is required to be recorded so as to calculate the time consumption of the whole establishing process, namely the time consumption of establishing the second PDU session; and simultaneously recording the monitoring condition of the downlink user data (specifically, the downlink user data traffic). In this way, the user equipment may determine the release policy of the first PDU session according to the recorded time consumed for establishing the second PDU session and the monitoring condition of the downlink user data, and make reference to the subsequent release of the first PDU session.

Optionally, in some embodiments, the releasing the first PDU session according to the monitoring result may include:

in the process of establishing the second PDU session, if the first PDU session is monitored to receive downlink user data, starting monitoring of the second PDU session;

and when the second PDU session is monitored to receive downlink user data, releasing the first PDU session.

In one specific example, if the current old PDU session (i.e., the first PDU session) receives downstream user data during the establishment of the new PDU session (i.e., the second PDU session), the user equipment may begin monitoring for the new PDU session. When the new PDU session receives the first packet of downlink user data, the UE initiates a release process of the old PDU session.

It is further noted that the user equipment may comprise an Application Processor (AP) and a session management module (SM). Thus, when the AP detects that the SSC mode 3 type PDU session is switched currently, the AP can initiate the establishment flow of a new PDU session at this time and record the time consumption for establishing a second PDU session and the monitoring condition of downlink user data; if the current old PDU session receives downlink user data during the process of establishing the new PDU session, the AP may start monitoring the new PDU session. When the new PDU session receives the first packet of downlink user data, the AP initiates the release process of the old PDU session.

in the process of establishing the second PDU session, if monitoring that the first PDU session does not receive downlink user data, starting a release timer and starting monitoring of the second PDU session;

and when the timing of the release timer exceeds a preset time length, or when the second PDU session is monitored to receive downlink user data before the timing of the release timer does not exceed the preset time length, releasing the first PDU session.

In this embodiment of the present application, the preset duration may be greater than or equal to the time consumed for establishing the second PDU session.

In a specific example, if the current old PDU session does not receive downlink user data during the process of establishing the new PDU session, the AP may start a release timer, and the timeout time of the release timer is set to be the time consumed for establishing the new PDU session, and the new PDU session is monitored. The AP may also initiate a release procedure for the old PDU session once the release timer expires or the new PDU session receives downlink user data before it expires.

Further, for a special scenario, after the SM layer on the user equipment side receives the PDU session modification command, the SM layer does not reject the command of the network equipment at this time, but reports to the AP and releases the current PDU session, and simultaneously establishes a new PDU session. After receiving the report, the AP triggers the release flow of the old PDU session, and then initiates the establishment flow of the new PDU session. Specifically, in some embodiments, recording process information may include at least: and sending a response message of successful PDU session modification to the network equipment and reporting a release message of the first PDU session to the AP through the SM.

Further, in some embodiments, after the first PDU session release is successful, the method may further include:

reporting a successful release message of the first PDU session to an AP through an SM;

accordingly, the establishing the second PDU session may include:

reporting a second PDU session establishment message to the AP through the SM;

and the AP starts the establishment flow of the second PDU session according to the received establishment message of the second PDU session.

That is, if the SM at the user equipment side detects that the number of currently established PDU sessions reaches a preset session threshold (for example, the maximum number supported by the SM), the SM locally records the process, replies a response message that the PDU session of the network equipment is successfully modified, and reports a release message for releasing the current PDU session to the AP. The AP then triggers the release procedure of the old PDU session. And after the old PDU session is successfully released, the SM reports a release success message, and simultaneously reports and establishes a new PDU session to the AP according to the locally recorded process information. The AP triggers the establishment procedure of the new PDU session. After the new PDU session is successfully established, the AP may use the new PDU session (i.e., the second PDU session) for traffic streaming with the network device.

In short, the embodiment of the present application provides a specific method that an AP layer service flow at a user equipment side can be switched from an old PDU session to a new PDU session, and the user equipment side can be locally implemented in a special scenario, so that the service flow can be continuously transmitted. In this way, the embodiment of the present application optimizes two scenarios (including a normal scenario and a special scenario) that have problems in the SSC mode 3 type PDU session handover process in the prior art specification, respectively, from the perspective of ensuring the continuity of user service data transmission based on the SSC mode. Under normal conditions, the method for switching the service flow specifically by the AP at the user equipment side can be given, so that the release of the old PDU session is uniformly initiated by the AP, the continuity of service flow transmission is ensured, and unnecessary resources are released in time. Under a certain specific condition, the method not only can ensure the continuous transmission of the user service data, but also can avoid the risk of transmission interruption of the user service data.

The embodiment provides a session management method which is applied to user equipment. Receiving a Protocol Data Unit (PDU) session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session; and under the condition that the number of the established PDU sessions is detected to be smaller than a preset session threshold value, establishing a second PDU session and recording a monitoring result; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow; and releasing the first PDU session according to the monitoring result. Therefore, the mode that the user equipment uniformly initiates the release of the old PDU session is adopted, the continuity of service flow transmission is ensured, and the time for the new PDU session and the old PDU session to exist at the same time can be shortened, so that the waste of resources by the user equipment and the network equipment can be avoided, the risk of transmission interruption of user data can be avoided, and the system performance can be improved.

In another embodiment of the present application, a detailed procedure is described for the release policy in the above-mentioned two scenarios (normal scenario and special scenario) with the starting point of trying to ensure the traffic transmission continuity and saving resources on the user equipment side and the network equipment side.

It is noted that the user equipment includes an Application Processor (AP) and a session management module (SM); wherein, in the user equipment, the SM is set on a Modem (Modem). In addition, data interaction can be carried out between the user equipment and the network equipment.

Aiming at a normal scene, under the condition of normal transmission, the problem caused by an old PDU session release strategy is uniformly solved by adopting a mode that an AP (access point) at a user equipment side initiates the release of the old PDU session, and meanwhile, a method for switching service flows at the user equipment side is provided for determining when the AP releases the old PDU session. Specifically, referring to fig. 5, a detailed flowchart of a session management method provided in an embodiment of the present application is shown. As shown in fig. 5, the detailed flow may include:

s501: and the network equipment and the AP transmit uplink/downlink data.

S502: the network device determines to switch the current old PDU session.

S503: and executing a PDU session modification process between the AP and the network equipment.

S504: the AP issues a first message command to the SM.

S505: and executing a new PDU session establishment process between the SM and the network equipment.

S506: the AP records the current time and monitors whether the old PDU session receives downlink user data.

S507: the SM reports the second message to the AP.

S508: the AP calculates the time consumption for establishing a new PDU session and records the monitoring condition of downlink user data; and carrying out service flow switching and releasing the old PDU session.

S509: and performing an old PCU session release flow between the AP and the network equipment.

It should be noted that the old PDU session is the first PDU session in the foregoing embodiment, and the new PDU session is the second PDU session in the foregoing embodiment.

It should be further noted that, for S503, executing a PDU session modification procedure between the AP and the network device may specifically include: the network equipment sends a PDU session modification command to the SM; the SM returns a PDU session modification completion command to the network equipment; the SM reports the first message to the AP. Here, the first message may be a message for modifying the current PDU session and carries a session reservation time. Thus, after receiving the PDU session modification command, the AP at the user side needs to determine whether the PDU session modification is in an SSC mode 3, and if the determination result is yes, the AP then issues a first message command to the SM, that is, a command for establishing a new PDU session.

Further, after S504, that is, after the AP issues the first message command to the SM, on one hand, the AP records the current time and monitors whether the old PDU session receives downlink user data, and on the other hand, a new PDU session establishment procedure is executed between the SM and the network device, that is, S505 and S506 are executed simultaneously.

Further, for S507, the SM reports a second message to the AP, where the second message may be a message that the session establishment is successful, and then the AP calculates the time consumed for establishing a new PDU session, and records the monitoring condition of the downlink user data; and then, switching the service flow according to the monitoring conditions and releasing the old PDU session.

Specifically, when the network side determines to switch the current PDU session, it may initiate a PDU session modification procedure. Then, the user side AP detects that the current modification is to the SSC mode 3 type PDU session, may initiate a new PDU session establishment procedure, record the current time, and monitor whether the old PDU session currently being modified receives downlink user data. Subsequently, after the new PDU session is successfully established, the AP records the time again to calculate the time consumed in the entire establishment process (i.e., the time consumed for establishing the new PDU session), and records the downlink user data monitoring result to make reference for the subsequent release decision.

In the embodiment of the present application, the AP may decide when to initiate the old PDU session release according to the following release policy:

(1) if the current old PDU session receives downstream user data during the establishment of the new PDU session, the AP begins monitoring the new PDU session. When the new PDU session receives the first packet of downstream user data, the AP may initiate a release procedure for the old PDU session.

(2) If the current old PDU session does not receive the downlink user data in the process of establishing the new PDU session, the AP starts a release timer, the overtime time of the release timer is the time consumption of the establishment process of the new PDU session, and the new PDU session is monitored at the same time. Once the release timer expires or before it expires the new PDU session receives downlink user data, the AP may initiate a release procedure for the old PDU session.

Further, through the release process of the PDU session, the old PDU session can be released, and then the new PDU session is used to perform traffic flow transmission with the network device.

For special scenes, after receiving a PDU session modification command, a SM at a user side does not reject the PDU session modification command of a network, but reports to an AP to release the current PDU session and establishes a new PDU session. After receiving the report, the AP triggers the release flow of the old PDU session, and then initiates the establishment flow of the new PDU session. The network device performs corresponding operations according to the received request of the user device. Specifically, referring to fig. 6, a detailed flowchart of another session management method provided in the embodiment of the present application is shown. As shown in fig. 6, the detailed flow may include:

s601: and the network equipment and the AP transmit uplink/downlink data.

S602: the network device determines to switch the current old PDU session.

S603: the network device sends a PDU session modify command to the SM.

S604: when the SM detects that the number of the currently established sessions reaches a preset session threshold value, the process is locally recorded.

S605: the SM returns a PDU session modification completion command to the network device.

S606: the SM reports the first message to the AP.

S607: the AP issues a first message command to the SM.

S608: and performing an old PDU session release process between the SM and the network equipment.

S609: the SM initiates the establishment of a new PDU session again according to the locally recorded content.

S610: the SM reports the second message to the AP.

S611: and the SM reports the third message to the AP.

S612: the AP issues a third message command to the SM.

S613: a new PDU session establishment procedure is performed between the SM and the network device.

S614: the SM reports the fourth message to the AP.

S615: and transmitting uplink/downlink data between the network equipment and the AP according to the new PDU session.

It should be noted that the old PDU session is the first PDU session described in the foregoing embodiment, and the new PDU session is the second PDU session described in the foregoing embodiment.

It should be further noted that the first message may be a message for releasing the current PDU session, and the first message command may be a command of a session release request, so as to instruct the SM to open a release procedure of an old PDU session; the second message may be a message that the session release is successful; the third message may be a message for establishing a new session, and the third message command may be a command of a session establishment request to instruct the SM to start an establishment procedure of a new PDU session; the fourth message may be a message that the session establishment is successful, so that the AP may implement traffic streaming with the network device according to the new PDU session.

Specifically, first, when the network side determines to switch the current PDU session, it initiates a PDU session modification procedure. Secondly, the user side SM detects that the number of the current PDU session establishment reaches the maximum number supported by the user side SM, locally records the process, replies the success of the PDU session modification of the network side, and reports and releases the current PDU session to the AP. Again, the AP triggers the release procedure of the old PDU session. And after the old PDU session is successfully released, the SM reports the message of successful release, and simultaneously reports and establishes a new PDU session to the AP according to the local record. And thirdly, the AP triggers the establishment process of the new PDU session. After the new PDU session is successfully established, the AP may use the new PDU session for traffic flow transmission.

In short, for the first normal scenario, a specific service flow switching method of an AP at a user side may be provided, and a manner of uniformly initiating release of an old PDU session by the AP is adopted, so that continuity of service flow transmission is ensured, a time for simultaneous existence of new and old PDU sessions is shortened as much as possible, and waste of resources by a user and a network may be avoided. The release strategy greatly optimizes the release strategy in the current technical specification, for example, a mode that resources are released as soon as possible and the service stream transmission is not guaranteed to be continuous or the service stream transmission is guaranteed to be continuous but resources are wasted after waiting for the maximum time. Therefore, an advantage is found in the embodiment of the application in the scenario of ensuring the transmission continuity of the service stream and saving resource.

For the second special scenario, a method of releasing the old PDU session first and then establishing a new PDU session connected to the same DN may be adopted, which may cause a short stop of traffic flow transmission on the PDU session, but compared to the method in the technical specification, can ensure that the traffic flow continues to be transmitted after the stop. And the stop time in the normal case should be in milliseconds, which is negligible for the user using the wireless device application, and can also try to ensure the continuity of the traffic flow.

The embodiment provides a session management method which is applied to user equipment. The specific implementation of the foregoing embodiment is elaborated in detail through the foregoing embodiment, and it can be seen that, through the technical solution of the foregoing embodiment, waste of resources by the user equipment and the network equipment can be avoided, and a risk of transmission interruption of user data can be avoided, which is beneficial to improving system performance.

In another embodiment of the present application, based on the same inventive concept as the foregoing embodiment, refer to fig. 7, which shows a schematic structural diagram of a user equipment 70 provided in an embodiment of the present application. As shown in fig. 7, the user equipment 70 may include: a receiving unit 701, an establishing unit 702 and a releasing unit 703; wherein,

a receiving unit 701 configured to receive a PDU session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session;

an establishing unit 702 configured to establish a second PDU session and record a monitoring result when detecting that the number of established PDU sessions is less than a preset session threshold; wherein the monitoring result at least comprises: establishing the second PDU session consumes time and carries out downlink user data flow;

a releasing unit 703 configured to release the first PDU session according to the monitoring result.

In some embodiments, the releasing unit 703 is further configured to release the first PDU session when detecting that the number of established PDU sessions is greater than or equal to a preset session threshold;

the establishing unit 702 is further configured to establish a second PDU session after the first PDU session is successfully released.

In some embodiments, referring to fig. 7, the user equipment 70 may further include a determining unit 704 configured to perform data interaction through the second PDU session.

In some embodiments, the determining unit 704 is further configured to determine a mode type of the first PDU session if it is detected that the number of established PDU sessions is less than a preset session threshold;

the establishing unit 702 is further configured to execute the steps of establishing the second PDU session and recording the monitoring result when the mode type of the first PDU session is the preset mode type.

In some embodiments, the establishing unit 702 is specifically configured to record a first time at the time of starting the second PDU session establishment; monitoring whether the first PDU session receives downlink user data or not in the process of establishing the second PDU session; and recording a second moment at the moment when the second PDU session is successfully established; calculating the time consumed for establishing the second PDU session according to the second time and the first time; and taking the time consumed for establishing the second PDU session and the downlink user data flow as the monitoring result for recording.

In some embodiments, the releasing unit 703 is specifically configured to, in the process of establishing the second PDU session, if it is monitored that the first PDU session receives downlink user data, start monitoring the second PDU session; and when it is monitored that the second PDU session receives downlink user data, releasing the first PDU session.

In some embodiments, the releasing unit 703 is specifically configured to, in the process of establishing the second PDU session, if it is monitored that the first PDU session does not receive downlink user data, start a release timer, and start monitoring the second PDU session; and when the timing of the release timer exceeds a preset time length, or when the second PDU session is monitored to receive downlink user data before the timing of the release timer does not exceed the preset time length, releasing the first PDU session.

In some embodiments, the preset duration is greater than or equal to the setup time of the second PDU session.

In some embodiments, the determining unit 704 is further configured to determine a mode type of the first PDU session if it is detected that the number of established PDU sessions is greater than or equal to a preset session threshold;

the establishing unit 702 is further configured to release the first PDU session when the mode type of the first PDU session is a preset mode type.

In some embodiments, the predetermined pattern type is traffic and session continuity SSC pattern 3.

In some embodiments, the user equipment comprises an application processor AP and a session management SM;

correspondingly, the releasing unit 703 is further configured to report a successful release message of the first PDU session to the AP through the SM;

the establishing unit 702 is further configured to report an establishment message of the second PDU session to the AP through the SM; and the AP starts the establishment flow of the second PDU session according to the received establishment message of the second PDU session.

In some embodiments, the preset session threshold is a maximum number of sessions supported by the user equipment.

It is understood that in this embodiment, a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc., and may also be a module, or may also be non-modular. Moreover, each component in this embodiment may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware or a form of a software functional module.

Based on the understanding that the technical solution of the present embodiment essentially or partly contributes to the prior art, or all or part of the technical solution may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the method of the present embodiment. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Accordingly, the present embodiment provides a computer storage medium for application to the user device 70, the computer storage medium storing a computer program which, when executed by at least one processor, implements the steps of the method of any of the preceding embodiments.

Based on the above-mentioned composition of the user equipment 70 and the computer storage medium, refer to fig. 8, which shows a specific hardware structure diagram of the user equipment 70 provided in the embodiment of the present application. As shown in fig. 8, may include: a communication interface 801, a memory 802, and a processor 803; the various components are coupled together by a bus system 804. It is understood that the bus system 804 is used to enable communications among the components. The bus system 804 includes a power bus, a control bus, and a status signal bus in addition to a data bus. For clarity of illustration, however, the various buses are labeled as bus system 804 in FIG. 8. The communication interface 801 is used for receiving and sending signals in the process of receiving and sending information with other external network elements;

a memory 802 for storing a computer program capable of running on the processor 803;

a processor 803 for executing, when running the computer program, the following:

receiving a Protocol Data Unit (PDU) session modification command; wherein, the PDU conversation amending command is used for indicating the switching of the current first PDU conversation; and

and releasing the first PDU session according to the monitoring result.

It will be appreciated that the memory 802 in the subject embodiment can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. The non-volatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of example, but not limitation, many forms of RAM are available, such as Static random access memory (Static RAM, SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous Dynamic random access memory (ddr Data Rate SDRAM, ddr SDRAM), Enhanced Synchronous SDRAM (ESDRAM), Synchronous chained SDRAM (Synchronous link DRAM, SLDRAM), and Direct memory bus RAM (DRRAM). The memory 802 of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

And the processor 803 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuits of hardware or instructions in the form of software in the processor 803. The Processor 803 may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 802, and the processor 803 reads the information in the memory 802, and completes the steps of the above method in combination with the hardware thereof.

It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the Processing units may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, micro-controllers, microprocessors, other electronic units configured to perform the functions described herein, or a combination thereof.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory and executed by a processor. The memory may be implemented within the processor or external to the processor.

Optionally, as another embodiment, the processor 803 is further configured to perform the steps of the method of any one of the previous embodiments when running the computer program.

The embodiment provides a user equipment which can comprise a receiving unit, a establishing unit and a releasing unit. Therefore, the technical scheme of the application adopts a mode that the user equipment uniformly initiates the release of the old PDU session, ensures the continuity of service flow transmission, and can also shorten the time for the new PDU session and the old PDU session to exist simultaneously, thereby avoiding the waste of resources by the user equipment and the network equipment, avoiding the risk of transmission interruption of user data, and being beneficial to improving the system performance.

In yet another embodiment of the present application, referring to fig. 9, a schematic structural diagram of a communication system 90 provided in the embodiment of the present application is shown. As shown in fig. 9, the communication system 90 may include a network device 901 and a user device 902. Here, the user equipment 902 may be the user equipment described in any of the preceding embodiments.

It should be noted that the communication system 90 according to the embodiment of the present application is not limited to a Long Term Evolution (LTE) system, a fourth Generation mobile communication (4G) system, a fifth Generation mobile communication (5G) system, a new air interface (NR) system, or a communication system of a subsequent Evolution. In the communication system, data interaction between the network device 901 and the user equipment 902 may be performed through a wireless network.

Thus, in the communication system 90, the network side determines for some reason to switch the PSA corresponding to the PDU session of the current traffic flow, at which time the network device 901 may send a PDU session modification command to the user equipment 902. After receiving the PDU session modification command, the ue 902 may divide the application scene into a normal scene and a special scene according to a comparison result between the number of established PDU sessions and a preset session threshold; and then, aiming at different application scenes, a corresponding optimization scheme is provided to determine when the user equipment releases the first PDU session (namely the old PDU session), so that the continuity of service flow transmission can be ensured, the time for simultaneously existing new and old PDU sessions can be shortened, the waste of resources by the user equipment and network equipment can be avoided, the risk of transmission interruption of user data can be avoided, and the system performance can be improved.

It should be noted that, in the present application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.

The methods disclosed in the several method embodiments provided in the present application may be combined arbitrarily without conflict to obtain new method embodiments.

Features disclosed in several of the product embodiments provided in the present application may be combined in any combination to yield new product embodiments without conflict.

The features disclosed in the several method or apparatus embodiments provided in the present application may be combined arbitrarily, without conflict, to arrive at new method embodiments or apparatus embodiments.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A session management method applied to a User Equipment (UE), the method comprising:

and releasing the first PDU session according to the monitoring result.

2. The method of claim 1, further comprising:

releasing the first PDU session when detecting that the number of the established PDU sessions is larger than or equal to a preset session threshold value;

3. The method according to claim 1 or 2, characterized in that the method further comprises:

and carrying out data interaction through the second PDU session.

4. The method of claim 1, wherein in case it is detected that the number of established PDU sessions is less than a preset session threshold, the method further comprises:

determining a mode type of the first PDU session;

5. The method of claim 4, wherein establishing the second PDU session and recording the monitoring result comprises:

calculating the time consumption for establishing the second PDU session according to the second time and the first time;

6. The method of claim 5, wherein the releasing the first PDU session according to the monitoring result comprises:

7. The method of claim 5, wherein the releasing the first PDU session according to the monitoring result comprises:

8. The method of claim 7, wherein the preset duration is greater than or equal to a time consumed for establishing the second PDU session.

9. The method according to claim 2, wherein in case it is detected that the number of established PDU sessions is greater than or equal to a preset session threshold, the method further comprises the steps of:

determining a mode type of the first PDU session;

and when the mode type of the first PDU session is a preset mode type, releasing the first PDU session.

10. The method of claim 4 or 9, wherein the predetermined pattern type is traffic and session continuity SSC pattern 3.

11. The method of claim 2, wherein the user equipment comprises an application processor AP and a session management module SM, and wherein after the session release of the first PDU is successful, the method further comprises:

accordingly, the establishing the second PDU session includes:

reporting a building message of the second PDU session to the AP through the SM;

12. The method of claim 1, wherein the preset session threshold is a maximum number of sessions supported by the UE.

13. User equipment, characterized in that the user equipment comprises a receiving unit, an establishing unit and a releasing unit; wherein,

the receiving unit is configured to be a Protocol Data Unit (PDU) session modification command; wherein the PDU session modification command is used for indicating switching of the current first PDU session;

14. A user device, wherein the user device comprises a memory and a processor; wherein,

the memory for storing a computer program operable on the processor;

the processor, when running the computer program, is configured to perform the method of any of claims 1 to 12.

15. A computer storage medium, characterized in that the computer storage medium stores a computer program which, when executed by at least one processor, implements the method of any one of claims 1 to 12.

16. A communication system, characterized in that the communication system comprises a network device and a user equipment according to claim 13 or 14.