CN117812549A

CN117812549A - Communication method and device

Info

Publication number: CN117812549A
Application number: CN202410229465.8A
Authority: CN
Inventors: 李海波
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2024-02-29
Filing date: 2024-02-29
Publication date: 2024-04-02

Abstract

The application provides a communication method and a communication device, wherein a terminal sends a tracking area update request message to a first network, the first network does not receive a tracking area update acceptance message, the terminal returns to a second network from the first network, the terminal sends a registration request message to the second network, the registration request message carries a first message, the registration request message is used for initiating mobility registration update, and the first message indicates that the terminal does not finish the tracking area update of the first network. Therefore, under the condition that the first network does not receive the tracking area update acceptance message, the terminal carries the first message in the registration request message in the process of carrying out mobility update registration by the second network, so as to inform the network that the tracking area update of the terminal in the first network is not completed, lay a foundation for the network to respond based on the condition, and reduce the possibility that the terminal cannot realize the service in the second network.

Description

Communication method and device

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a communications method and apparatus.

Background

In the field of mobile communication, a terminal realizes services such as conversation and short message through interaction with a mobile communication network.

Currently, in some cases, a service of a terminal based on a mobile communication network may have a problem that cannot be achieved, for example, after the terminal returns to a 5G network from a 4G network, other terminals initiate a call to the terminal, but cannot establish a call service with the terminal.

Disclosure of Invention

The application provides a communication method and a communication device, and aims to solve the problem that a terminal cannot realize services based on a mobile communication network.

In order to achieve the above object, the present application provides the following technical solutions:

a first aspect of the present application provides a communication method, including: the method comprises the steps that a terminal sends a tracking area update request message in a first network, the first network does not receive a tracking area update acceptance message, the terminal returns to a second network from the first network, the terminal sends a registration request message in the second network, the registration request message carries a first message, the registration request message is used for initiating mobility registration update, and the first message indicates that the terminal does not complete the tracking area update in the first network. Therefore, when the first network does not receive the tracking area update accept message, the terminal carries the first message in the process of mobility update registration of the second network, so as to inform the network that the tracking area update of the terminal in the first network is not completed, lay a foundation for the network to respond based on the condition (such as acquiring the information of the terminal from the first network, etc.), and reduce the possibility that the terminal cannot realize the service in the second network because the network cannot find the information (such as the context information) of the terminal.

In some implementations, before the terminal sends the tracking area update request message at the first network, the method further includes: responsive to an operation at the terminal to close the second network, the terminal returns from the second network to the first network, and correspondingly, the terminal returns from the first network to the second network, comprising: the terminal returns from the first network to the second network in response to an operation to open the second network at the terminal. For example, the user performs an operation of closing the 5G network at the terminal, the terminal returns to the 4G network from the 5G network, the user performs an operation of opening the 5G network at the terminal, and the terminal returns to the 5G network from the 4G network. It can be seen that, in some cases, if the user opens the 5G network quickly after the terminal closes the 5G network, the terminal may not be able to receive or pass through the 5G network, and the communication method provided by the present application is applicable to this scenario, so that the possibility that the terminal cannot receive or pass through the 5G network is reduced in this scenario.

In some implementations, the first message includes: the tracking area update request message, or the notification message, indicates that the terminal does not receive the tracking area update accept message in the first network, thereby facilitating the second network to acquire the information of the terminal from the first network based on the tracking area update request message. The first message is a tracking area update request message, is compatible with the existing communication protocol, and reduces the network reconstruction cost. The first message is a notification message, which is favorable for the network to perform a more flexible response mode, for example, the second network can acquire the information of the terminal from the first network and can also directly trigger the terminal to perform initial registration.

In some implementations, before the second network sends the registration request message, further comprising: the terminal determines that the tracking area update message has been sent in the first network, so as to make a more accurate determination that the terminal has not completed tracking area tracking in the first network.

In some implementations, before the second network sends the registration request message, further comprising: the terminal determines that the tracking area update accept message is not received in the first network, so that more accurate determination can be conveniently made on the incomplete tracking area tracking of the terminal in the first network.

In some implementations, after the terminal sends the registration request message at the second network, further comprising: the terminal receives the registration rejection message and initiates initial registration in the second network. The initial registration enables the network to acquire information of the terminal, which is beneficial to improving the possibility of the terminal realizing the service in the second network.

In some implementations, the registration request message also carries a first field, where the first field indicates that the type of the registration request message is a mobility registration update, and this is compatible with existing communication protocols, which is beneficial to reducing the modification costs of the terminal and the network.

A second aspect of the present application provides a communication method, comprising: the terminal sends a tracking area update request message in the first network, and the tracking area update accept message is not received in the first network, the terminal returns to the second network from the first network, and the terminal initiates initial registration in the second network. Unlike the prior art, the terminal sends the tracking area update request message in the first network, and after the first network returns to the second network without receiving the tracking area update accept message, the mobility registration update is not initiated any more, but the initial registration is initiated, so that the network can acquire the information of the terminal, thereby improving the possibility of success of the service of the terminal in the second network.

In some implementations, before the terminal sends the tracking area update request message at the first network, the method further includes: responsive to an operation to close the second network at the terminal, the terminal returning from the second network to the first network, the terminal returning from the first network to the second network, comprising: the terminal returns from the first network to the second network in response to an operation of the terminal to open the second network.

In some implementations, before the terminal initiates the initial registration at the second network, further comprising: the terminal determines that the tracking area update is not completed in the first network. Since initial registration at least results in a large network change, determining that tracking area updates are incomplete in the first network is advantageous in ensuring that initial registration does occur in the event that it is needed to reduce unnecessary network changes.

In some implementations, determining that tracking area updates are not complete at the first network includes: it is determined that the tracking area update request message has been sent at the first network and that the tracking area update accept message has not been received. Based on the information sent by the tracking area updating flow and the received information, incomplete tracking area updating is judged, and a more accurate judgment result can be obtained.

A third aspect of the present application provides a communication method, comprising: the core network equipment of the second network receives a registration request message sent by the terminal, wherein the registration request message carries a notification message which indicates that the terminal is not complete in updating the tracking area of the first network, and the registration request message is used for initiating mobility registration updating in the second network. Because the registration request message for initiating the mobility registration update carries the notification message, the second network can learn that the terminal does not complete the tracking area update in the first network, thereby laying a foundation for the second network to be able to improve the response of the terminal to successfully realize the service in the second network.

In some implementations, after receiving the registration request message sent by the terminal, the method further includes: the core network device of the second network acquires the routing information of the terminal from the core network device of the first network, so as to improve the possibility that the terminal successfully realizes the service based on the second network.

In some implementations, after receiving the registration request message sent by the terminal, the method further includes: the core network device of the second network sends a registration rejection message to the terminal, and the registration rejection message triggers the terminal to initiate initial registration to the core network device of the second network. The initial registration is beneficial to improving the possibility of the terminal successfully implementing the service in the second network.

A fourth aspect of the present application provides a terminal, comprising: and the processor comprises a baseband processor, and the baseband processor is used for realizing the communication method provided in the first aspect or the second aspect of the application.

In some implementations, the processor further includes an application processor, the baseband processor further configured to implement a communication function based on the first network or the second network, the application processor configured to send a message to the baseband processor to turn off or turn on the second network.

A fifth aspect of the present application provides a chip comprising: a modem for implementing the communication method provided in the first aspect or the second aspect of the present application.

A sixth aspect of the present application provides a network device, comprising: a memory for storing a computer program and a processor for running the computer program to implement the communication method of the third aspect of the present application.

Drawings

FIG. 1 is a diagram of an example of a scenario in which a handset implements a service based on a 5G network or a 4G network;

FIG. 2 is a flow chart of a mobile phone registering in a 5G network after returning to the 5G network from a 4G network;

FIG. 3 is a further flowchart of a mobile phone completing registration in a 5G network after returning from a 4G network to the 5G network;

fig. 4 is a diagram illustrating a structure of a terminal according to an embodiment of the present application;

FIG. 5 is a flow chart of a communication method disclosed in an embodiment of the present application;

FIG. 6 is a flow chart of yet another communication method disclosed in an embodiment of the present application;

fig. 7 is a flow chart of yet another communication method disclosed in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include, for example, "one or more" such forms of expression, unless the context clearly indicates to the contrary. It should also be understood that in embodiments of the present application, "one or more" means one, two, or more than two; "and/or", describes an association relationship of the association object, indicating that three relationships may exist; for example, a and/or B may represent: a alone, a and B together, and B alone, wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.

Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

The plurality of the embodiments of the present application refers to greater than or equal to two. It should be noted that, in the description of the embodiments of the present application, the terms "first," "second," and the like are used for distinguishing between the descriptions and not necessarily for indicating or implying a relative importance, or alternatively, for indicating or implying a sequential order.

With the development of mobile communication, most terminals support multiple communication systems, and taking fig. 1 as an example, a mobile phone can implement a service based on a 5G network or a service based on a 4G network.

The inventor finds that in the research process, in the scene that the terminal returns to the 5G network from the 4G network, the terminal may have the problem that the called party cannot receive the short message for a long time, and the possibility that the calling party and the short message sending service are abnormal is low.

Assuming that the second terminal returns from the 4G network to the 5G network, the called talk-spurt can be understood as: the first terminal initiates a call to the second terminal, but a call cannot be established between the first terminal and the second terminal. The failure to receive a short message can be understood as: the first terminal sends the short message to the second terminal, but the second terminal does not receive the short message.

Next, the cause of the problem that the terminal is not able to receive a short message or is not able to receive a long-term called party will be analyzed by referring to the flow shown in fig. 2 and 3, a case will be described in which a terminal is taken as a mobile phone, a radio access device of a 4G network is denoted by LTE, a radio access device of a 5G network is denoted by NR, and core networks of the 4G network and the 5G network are collectively referred to as a core network.

Fig. 2 shows an example of a procedure for completing registration after the mobile phone returns to the 5G network from 4G, where the procedure shown in fig. 2 enables the mobile phone to be called normally and receive a short message, and fig. 2 includes the following steps:

s201, the handset is triggered to return from the 5G network to the 4G network.

In some implementations, the handset shuts down the 5G network or the NR network, causing the handset to return from the 5G network to the 4G network. In other implementations, poor quality of the 5G network results in the handset returning from the 5G network to the 4G network.

The above implementations are by way of example only and not by way of limitation.

The mobile phone is triggered to return to the 4G network from the 5G network at least comprises: the handset searches for 4G cells and camps on the 4G cells.

S202, the mobile phone and LTE complete radio resource control (Radio Resource Control, RRC) access.

S203, the mobile phone sends a tracking area update request (Tracking Area Update Request) message to the LTE.

That is, the handset initiates a tracking area update (Tracking Area Update, TAU) procedure after the 4G cell.

S204, LTE sends Tracking Area Update Request message to the core network.

S205, the core network sends a tracking area update accept message (Tracking Area Update Accept) message to LTE.

S206, the LTE sends Tracking Area Update Accept information to the mobile phone.

It is assumed here that S207 is performed after S206.

S207, after receiving the Tracking Area Update Accept message, the mobile phone returns to the 5G network from the 4G network.

In some implementations, the handset opens a 5G or NR network, causing the handset to return from the 4G network to the 5G network. In other implementations, the quality of the 5G network is improved resulting in the handset returning from the 4G network to the 5G network. The above implementations are by way of example only and not by way of limitation.

S208, the mobile phone sends a registration request (Registration Request) message to the NR, wherein the registration request message carries a tracking area update request (Tracking Area Update Request, TAU req) message.

Based on the existing communication protocol, in the scenario defined in S201-S207, in this step, the mobile phone initiates a registration procedure for mobility and periodic registration update to the NR (i.e., the registration type is mobility registration update), and in the scenario defined in S201-S207, the mobile phone initiated registration for mobility and periodic registration update can satisfy the following conditions: 1) the UE in the single registration mode performs an intersystem change from S1 mode to N1 mode, 2) the registration procedure is initiated in 5GMM-IDLE mode, 3) the UE has received an indication from the network to support the N26 interface, in case the above conditions are met, the TAU req message is carried in the registration request based on the communication protocol specification.

The type of registration request message sent in this step is mobility registration update (mobility registration updating, MRU) based on the existing communication protocol.

S209, NR sends a registration request carrying TAU req message to the core network.

S210, the core network sends a registration accept (Registration Accept) message to the NR.

S211, NR sends Registration Accept message to the handset.

To this end, the handset resides in the NR and is in an IDLE (IDLE) state. Because the core network can acquire the TAU req message, the core network can acquire the information (such as context information) of the mobile phone in the 4G network, so that the called party and the short message can be normally received.

Fig. 3 is an example of a registration procedure of a mobile phone from a 4G network back to a 5G network, which may cause a problem that a terminal is not enabled or cannot receive a short message for a long time, and fig. 3 includes the following steps:

s301, responding to the operation of closing the 5G network by the user, and returning to the 4G network from the 5G network by the mobile phone.

The handset returns to the 4G network from the 5G network at least comprises: the handset searches for 4G cells and camps on the 4G cells.

S302, the mobile phone and the LTE finish RRC access.

S303, the handset sends a tracking area update request (Tracking Area Update Request) message to LTE.

And S304, the LTE sends Tracking Area Update Request information to the core network.

Here, it is assumed that in the case where the handset has not received the Tracking Area Update Accept message, the user triggers to open the 5G network, i.e. S305 is performed.

S305, the mobile phone returns to the 5G network from the 4G network in response to the operation of opening the 5G network by the user.

Returning from the 4G network to the 5G network includes at least: a search for 5G cells is performed and camping on 5G cells.

S306, the mobile phone sends a registration request (Registration Request) message to the NR.

The inventors found that: based on the existing communication protocol, because the handset does not receive the Tracking Area Update Accept message after S304, the handset may also consider the last (last) registered network as a 5G network instead of a 4G network, and thus the handset determines that the aforementioned "1) single registration mode UE performs an intersystem change from S1 mode to N1 mode" condition, and thus the registration request sent by S306 does not carry a TAU req message.

That is, S306 differs from S208 in that: the mobile phone does not carry TAU req message in the registration request message for mobility and periodic registration update sent to the NR.

S307, NR sends Registration Request message to the core network.

It will be appreciated that the Registration Request message forwarded by the NR to the core network also does not carry a TAU req message.

S308, the core network sends registration acceptance (Registration Accept) message to NR

S309, NR sends Registration Accept message to handset.

To this end, the handset resides in the NR and is in an IDLE (IDLE) state.

The inventors also found in the study that: because the core network does not acquire the TAU req message sent by the mobile phone in the 4G network, it is not possible to acquire information (such as context information) of the mobile phone in the 4G network. Therefore, even though the core network sends out Registration Accept message, it may not be compatible with TAU req message received by the 4G network, so that when a call to a mobile phone or a short message sent to the mobile phone is received, it cannot be known that paging is performed on the mobile phone by the NR (5G) network, and therefore, the mobile phone is not called or cannot receive the short message.

As can be seen from fig. 2 and fig. 3, in the scenario that the mobile phone quickly returns to the 5G network after leaving the 5G network, the mobile phone may have sent a tracking area update request message in the 4G network, but has not received a tracking area accept message, and based on the existing protocol, the mobile phone will not carry the tracking area update request message in the registration request for mobility and periodic registration update after returning to the 5G network, so that the problem that the mobile phone is not called or cannot receive a short message may be caused.

In order to solve the above-described problems, embodiments of the present application disclose a communication method based on the studies of the inventors on the sources causing the above-described problems. The communication method is applied to the terminal.

In the embodiments provided herein, the terminal may be in various forms, such as a mobile phone (mobile phone), a tablet computer (Pad), a computer with a wireless transceiving function, a Virtual Reality (VR) terminal device, an augmented reality (augmented reality, AR) terminal device, a wireless terminal in industrial control (industrial control), a vehicle-mounted terminal device, a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medium), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation security (transportation safety), a wireless terminal in smart city (smart city), a wireless terminal in smart home (smart home), a wearable terminal device, and the like. A terminal may also be referred to as a terminal device, user Equipment (UE), access terminal device, vehicle-mounted terminal, industrial control terminal, UE unit, UE station, mobile station, remote terminal device, mobile device, UE terminal device, wireless communication device, UE agent, UE apparatus, or the like. The terminal may also be a fixed terminal or a mobile terminal.

The terminal realizes a communication system depending on a communication function, which can be a second generation (2G) communication system and a third generation (3G) communication system, can be an LTE system (4G) communication system, can be a fifth generation (5G) communication system, can be a mixed architecture of LTE and 5G, can be a 5G new wireless (5G New Radio,5G NR) system, and can be a new communication system in future communication development.

The present embodiment is described by taking a 4G network and a 5G network as examples, but is not limited thereto.

The access device for communicating with the terminal may be a base station, and the base station may be any device located on a network side and having a wireless transceiver function, including but not limited to: an evolved base station (NodeB or eNB or e-NodeB, evolutional Node B) in long term evolution (long term evolution, LTE), a base station (gnnodeb or gNB) or transceiver point (transmission receiving point/transmission reception point, TRP) in New Radio (NR), a base station for 3GPP subsequent evolution, an access node in Wi-Fi system, a wireless relay node, a wireless backhaul node, etc. The base station may be: macro base station, micro base station, pico base station, small station, relay station, balloon station, or the like. A base station may include one or more co-sited or non-co-sited transmission points (Transmission Reception Point, TRP). The base station may also be a radio controller, a Centralized Unit (CU), and/or a Distributed Unit (DU) in the cloud radio access network (cloud radio access network, CRAN) scenario. The base station may communicate with the terminal or may communicate with the terminal through a relay station. The terminal may communicate with a plurality of base stations of different technologies, for example, the terminal may communicate with a base station supporting an LTE network, may communicate with a base station supporting a 5G network, and may perform dual connectivity with the base station supporting the LTE network and the base station supporting the 5G network.

The network device in communication with the access means may be a core network device, the network device comprising at least a memory and a processor.

Fig. 4 is a diagram illustrating a structure of a terminal disclosed in an embodiment of the present application, including: processor 10, external memory interface 20, display screen 30, internal memory 40, antenna 1, antenna 2, mobile communication module 50, and wireless communication module 60, etc.

It will be appreciated that the structure illustrated in this embodiment does not constitute a specific limitation on the terminal. In other embodiments, the terminal may include more or fewer components than shown, or certain components may be combined, or certain components may be split, or different arrangements of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

The processor 10 may include one or more processing units including at least: an application processor (application processor, AP) and a Modem processor (Modem), wherein the different processing units may be separate devices or may be integrated in one or more processors. At least one chip constitutes a processing unit, one of the chips is a baseband processing chip, and the baseband processing chip comprises one or more modems.

In the embodiment of the present application, an example of the function of the AP is to send a message to the Modem to close or open the 5G network in response to an operation of closing or opening the 5G network by the user. The Modem is used for implementing the baseband communication function, and specific functions implemented in the embodiments of the present application will be described in detail with reference to the following embodiments.

The external memory interface 20 may be used to connect an external memory card, such as a Micro SD card, to realize the memory capability of the extension terminal. The external memory card communicates with the processor 10 via an external memory interface 20 to implement data storage functions. For example, files such as music, video, etc. are stored in an external memory card.

The internal memory 40 may be used to store computer executable program code that includes instructions. The processor 10 executes various functional applications of the terminal and data processing by executing instructions stored in the internal memory 40.

The wireless communication function of the terminal can be realized by the antenna 1, the antenna 2, the mobile communication module 50, the wireless communication module 60, a modem processor, a baseband processor, and the like.

The antennas 1 and 2 are used for transmitting and receiving electromagnetic wave signals. Each antenna in the terminal may be used to cover a single or multiple communication bands. Different antennas may also be multiplexed to improve the utilization of the antennas. For example: the antenna 1 may be multiplexed into a diversity antenna of a wireless local area network. In other embodiments, the antenna may be used in conjunction with a tuning switch.

The mobile communication module 50 may provide a solution for wireless communication including 2G/3G/4G/5G or the like applied on the terminal. The mobile communication module 50 may include at least one filter, switch, power amplifier, low noise amplifier (low noise amplifier, LNA), etc. The mobile communication module 50 may receive electromagnetic waves from the antenna 1, filter, amplify, and the like the received electromagnetic waves, and transmit the electromagnetic waves to the modem processor for demodulation. The mobile communication module 50 can amplify the signal modulated by the modem processor, and convert the signal into electromagnetic waves through the antenna 1 to radiate. In some embodiments, at least some of the functional modules of the mobile communication module 50 may be provided in the processor 10. In some embodiments, at least some of the functional modules of the mobile communication module 50 may be provided in the same device as at least some of the modules of the processor 10. In some embodiments, the terminal initiates or receives a call request through the mobile communication module 50 and the antenna 1.

Fig. 5 is a flow chart of a communication method disclosed in an embodiment of the present application, including the following steps:

s501, the terminal returns to the 4G network from the 5G network.

In some implementations, the user turns off the 5G network of the terminal, triggering the terminal to return from the 5G network to the 4G network. An example is S5011-S5012: the user closes the 5G network of the terminal based on the interface of the terminal, the AP in the terminal sends a message for closing the 5G network to the Modem based on the operation of closing the 5G network of the terminal by the user, and the Modem responds to the message for closing the 5G network to search for an LTE (i.e. 4G) cell and reside in the 4G cell (i.e. search and residence of the LTE cell).

In other implementations, other reasons, such as poor quality of the 5G network, can trigger the terminal to return from the 5G network to the 4G network, which is not limited to S5011.

S502, the Modem and the LTE complete RRC access.

S503, the Modem sends Tracking Area Update Request message to LTE.

It will be appreciated that S503 needs to be performed first with S502 based on a communication protocol, and that S502 may not be performed, and S502 is not an essential step.

S504, LTE sends Tracking Area Update Request message to the core network.

In this embodiment, it is assumed that after the Modem issues the Tracking Area Update Request message and has not received the Tracking Area Update Accept message, the user operates the terminal to open the 5G network, i.e. the following steps are performed.

It will be appreciated that before S505 is performed, the core network may have sent out a Tracking Area Update Accept message, but not yet transmitted to the terminal, or the core network may not have sent out a Tracking Area Update Accept message. To highlight that the terminal did not receive the Tracking Area Update Accept message, in fig. 5, it is assumed that the core network has sent Tracking Area Update Accept a message, but has not yet transmitted to the terminal.

S505, the Modem returns to the 5G network from the 4G network.

In some implementations, the user opens the 5G network of the terminal, triggering the terminal to return from the 4G network to the 5G network. One example is S5051-S5052: the user opens the 5G network of the terminal based on the interface of the terminal, the AP in the terminal sends a message for opening the 5G network to the Modem based on the operation of opening the 5G network of the terminal by the user, and the Modem responds to the message for opening the 5G network, searches for a 5G cell, and resides in the 5G cell (search and residence of the 5G cell).

In other implementations, other reasons, such as a quality of the 5G network becoming better, can trigger the terminal to return from the 4G network to the 5G network, but is not limited to S5051.

S506, the Modem sends Registration Request information to the NR, and Registration Request information carries the TAU req information and the first field.

It will be appreciated that the Registration Request message sent in S506 is a registration request message for mobility registration update, that is, the type of registration request message sent in this step is mobility registration update (mobility registration updating, MRU).

In some implementations, the first field is used to indicate that the type of registration is a mobility registration update, that is, the Registration Request message indicates that the type of registration is requested by carrying a different field, the first field indicating that the type of registration is a mobility registration update. One example of the first field is "010".

Of course, other means of indicating the type of registration may be used.

In some implementations, the Modem determines that a Tracking Area Update Request message has been sent, then sends Registration Request message to the NR carrying a TAU req message.

In other implementations, the Modem determines that a Tracking Area Update Request message has been sent and no Tracking Area Update Accept message has been received, then sends a Registration Request message to the NR carrying a TAU req message.

One specific way of determining that a Tracking Area Update Request message has been sent is: an identification (flag) is set, after Tracking Area Update Request is sent, the flag is set to 1, and after receiving a TAU accept or reject message, the flag is set to 0, so it can be judged by the flag whether Tracking Area Update Request has been sent. Another specific mode is as follows: setting a state machine, setting a corresponding state machine state for a step in the TAU procedure, for example, entering an A state after a TAU request (Tracking Area Update Request) is sent, entering a B state after receiving a TAU accept, setting a complete message to a C state after sending the TAU complete message, and judging whether the TAU request is sent completely or not based on the state machine state.

In still other implementations, the Modem does not determine whether a Tracking Area Update Request message has been sent, but instead directly sends Registration Request messages carrying TAU req messages in the event Registration Request messages need to be sent.

It can be understood that, as shown in the flow of fig. 3, since the "1) single registration mode UE performs the inter-system change from S1 mode to N1 mode" condition is not satisfied, the Modem should send Registration Request message without TAU req message, but in this step, the Modem sends Registration Request message with TAU req message, which lays a foundation for solving the problem that the called party cannot pass or cannot receive the short message in the 5G network.

S507, NR sends Registration Request message carrying TAU req message to the core network.

S507 makes 5G core network possible to obtain information (such as context information) of terminal from 4G core network so as to lay foundation for solving problem that terminal is not called or not able to receive short message in 5G network.

The specific flow executed by the core network will not be described here in detail.

Based on the communication protocol, it is possible for the core network to perform S508 and also S510.

And S508, the core network sends Registration Accept information to the NR.

S509, NR sends Registration Accept message to Modem.

To this end, the handset resides in the NR and is in an IDLE (IDLE) state. Because the core network can acquire the TAU req message, the core network can acquire information (such as context information) of the mobile phone under the 4G network, so that the called party and the short message can be normally received.

It will be appreciated that it is assumed here that other specifications of the communication protocol are satisfied in addition to the condition that "1) the UE of the single registration mode performs the intersystem change from the S1 mode to the N1 mode is not satisfied, so that the terminal can normally receive the called party as well as the short message. Under the condition of considering other regulations of the communication protocol, the communication method provided by the embodiment can improve the possibility that the terminal can normally receive the called party and the short message in the scene that the terminal returns to the 5G network from the 4G network.

S510, the core network sends a registration reject (Registration Reject) message to the NR.

S511, NR sends Registration Reject message to Modem.

The communication protocol and the specific flow according to which the core network sends the Registration Reject message are not described in detail here.

S512, the Modem initiates initial registration to the network in response to the Registration Reject message.

The initial registration is of a different type than the S506 initiated mobility registration update. Based on the communication protocol, the Modem initiates an initial registration with the network in response to the Registration Reject message.

The specific flow of initial registration is not described here in detail.

After the initial registration is completed, the terminal can normally answer the called and short messages. Considering other faults or factors, based on the flow shown in fig. 5, the possibility that the terminal normally receives the called party and the short message after returning to the 5G network from the 4G network can be improved.

Based on the flow shown in fig. 5, when the terminal initiates a registration request of a mobility registration update type, the terminal carries a TAU request message, which is beneficial to improving the possibility of the terminal being normally called and receiving a short message after the 5G network completes registration.

Fig. 6 is a schematic diagram of another communication method according to an embodiment of the present application, which is different from the flow shown in fig. 5 in that: carried in the Registration Request message is not a TAU req message, but a notification message indicating that the TAU of the terminal in the 4G network is not complete.

In some implementations, the Modem determines that a Tracking Area Update Request message has been sent, further, may also determine that no Tracking Area Update Accept message has been received, and sends a Registration Request message carrying a notification message to the NR. The specific determination method can be referred to as the determination method in S506. In other implementations, the Modem does not determine whether a Tracking Area Update Request message has been sent, but instead directly sends Registration Request messages carrying notification messages in the event Registration Request messages need to be sent. The notification message may be used as a field in the Registration Request message for registration of the mobility update type.

As described above, the notification message is used to inform that the TAU of the 5G network core network device in the core network is not completed in the 4G network, and the 5G network core network device obtains information (including routing information such as context information) of the terminal from the 4G network core network device in some implementations, and performs S608, so as to lay a foundation for the terminal to normally receive the called and the short message in the 5G network, and in other implementations, the 5G network core network device performs S610, i.e. directly refuses the registration request, so as to trigger the terminal to perform initial registration, and can also lay a foundation for the terminal to normally receive the called and the short message in the 5G network.

The specific implementation of the steps in fig. 6 can be seen in fig. 5, and will not be described here again.

Fig. 7 is a schematic diagram of another communication method according to an embodiment of the present application, which is different from the flow shown in fig. 5 or fig. 6 in that: and in the case that the terminal judges that the TAU is not finished, initiating initial registration to the network.

The following steps are included in fig. 7:

s701, the terminal returns to the 4G network from the 5G network.

S702, the Modem and the LTE complete RRC access.

S703, the Modem sends Tracking Area Update Request message to the core network through LTE.

In this embodiment, it is assumed that after the Modem issues the Tracking Area Update Request message, and in the case where the Tracking Area Update Accept message has not been received yet, the terminal is triggered back to the 5G network.

S704, the Modem returns to the 5G network from the 4G network.

S705, the Modem judges whether the TAU is not finished.

In some implementations, the Modem determines that the message Tracking Area Update Request has been sent in the 4G network, but does not receive the message Tracking Area Update Accept, and obtains a determination that the TAU is not complete.

In other implementations, as previously described, the Modem determines whether the TAU is incomplete based on state machine state.

Since initial registration at least results in a large change in core network data compared to registration for mobility and periodicity, in this step, it is necessary to determine that TAU has not completed triggering the initial registration procedure.

It is understood that S706 may be directly performed without performing S705. S705 may also be replaced with a determination that a Tracking Area Update Request message has been sent.

If the judgment result is yes, S706-S707 are performed, and if the judgment result is no, S708-S709 are performed.

S706, the Modem sends a registration request (Registration Request) message to the core network through NR, and the Registration Request message carries a second field.

The second field indicates that the registration type is initial registration (Initial Registration). One example of the second field is "001". It will be appreciated that the indication of initial registration with the second field is merely exemplary and not limiting.

S707, the core network sends a register receiving (Registration Accept) message to the Modem through NR.

Thus, the terminal finishes the initial registration in the network, so that the 5G network core network has the information of the terminal, thereby improving the possibility that the terminal normally receives the called party and the short message.

It will be appreciated that it is possible that the initial registration of the terminal with the network is unsuccessful, in which case one implementation may see S510-S512, i.e. the terminal may initiate an initial registration again. Another implementation may refer to the provision in the communication protocol that the initial registration is unsuccessful, which is not described here again.

S708, the Modem sends a Registration Request message with the type MRU to the core network through NR.

The Registration Request message sent in this step carries a TAU req message.

And S709, the core network sends Registration Accept information to the Modem through NR.

In the flow shown in fig. 7, after the terminal determines that the TAU fails, initial registration is initiated to the network, so that the network can newly create information of the terminal, and the possibility that the terminal that is successfully registered is not enabled or cannot receive a short message for a long time is improved.

Claims

1. A method of communication, comprising:

the terminal sends a tracking area update request message to a first network, and the first network does not receive a tracking area update accept message;

the terminal returns to a second network from the first network;

the terminal sends a registration request message in the second network, wherein the registration request message carries a first message, the registration request message is used for initiating mobility registration update, and the first message indicates that the terminal does not complete the update in the tracking area of the first network.

2. The communication method according to claim 1, further comprising, before the terminal transmits the tracking area update request message at the first network:

responsive to an operation to shut down the second network at the terminal, the terminal returns from the second network to the first network;

the terminal returns from the first network to a second network, comprising:

the terminal returns from the first network to the second network in response to an operation to open the second network at the terminal.

3. The communication method according to claim 1 or 2, wherein the first message comprises:

the tracking area update request message, or a notification message, indicates that the terminal has not received a tracking area update accept message at the first network.

4. The communication method according to claim 1 or 2, characterized in that before the second network transmits a registration request message, further comprising:

the terminal determines that the tracking area update message has been sent at the first network.

5. The communication method according to claim 4, wherein before the second network transmits the registration request message, further comprising:

the terminal determines that a tracking area update accept message has not been received at the first network.

6. The communication method according to claim 1 or 2, characterized by further comprising, after the terminal transmits a registration request message at the second network:

the terminal receives a registration rejection message;

the terminal initiates an initial registration in the second network.

7. A communication method according to claim 1 or 2, characterized in that the registration request message also carries a first field indicating that the type of registration request message is a mobility registration update.

8. A method of communication, comprising:

the terminal returns to a second network from the first network;

the terminal initiates an initial registration in the second network.

9. The communication method according to claim 8, further comprising, before the terminal transmits the tracking area update request message at the first network:

the terminal returns from the first network to a second network, comprising:

the terminal returns from the first network to the second network in response to an operation of the terminal to open the second network.

10. A communication method according to claim 8 or 9, characterized in that before the terminal initiates the initial registration at the second network, it further comprises:

the terminal determines that tracking area updates are not complete at the first network.

11. The communication method of claim 10, wherein the determining that tracking area updates are not complete at the first network comprises:

it is determined that the tracking area update request message has been sent at the first network and that the tracking area update accept message has not been received.

12. A method of communication, comprising:

the core network equipment of the second network receives a registration request message sent by a terminal, wherein the registration request message carries a notification message, the notification message indicates that the update of a tracking area of the terminal in the first network is not completed, and the registration request message is used for initiating mobility registration update in the second network.

13. The communication method according to claim 12, further comprising, after the registration request message transmitted by the receiving terminal:

and the core network equipment of the second network acquires the route information of the terminal from the core network equipment of the first network.

14. The communication method according to claim 12, further comprising, after the registration request message transmitted by the receiving terminal:

and the core network equipment of the second network sends a registration rejection message to the terminal, and the registration rejection message triggers the terminal to initiate initial registration to the core network equipment of the second network.

15. A terminal, comprising:

a processor, the processor comprising a baseband processor;

the baseband processor being configured to implement the communication method of any of claims 1-11.

16. The terminal of claim 15, wherein the terminal comprises a base station,

the processor further includes an application processor;

the baseband processor is further used for realizing a communication function based on the first network or the second network;

the application processor is configured to send a message to the baseband processor to close or open the second network.

17. A chip, comprising:

a modem for implementing the communication method of any of claims 1-11.

18. A network device, comprising: a memory and a processor;

the memory is adapted to store a computer program, the processor being adapted to run the computer program to implement the communication method of any of claims 12-14.