CN115002872A

CN115002872A - Communication method and device

Info

Publication number: CN115002872A
Application number: CN202110405669.9A
Authority: CN
Inventors: 姚楚婷; 李兆俊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-03-02
Filing date: 2021-04-15
Publication date: 2022-09-02
Also published as: WO2022183933A1

Abstract

The application relates to a communication method and equipment. In the process of selecting a network, terminal equipment obtains first indication information, wherein the first indication information is used for indicating that the terminal equipment has a radio link failure event in the network corresponding to the first indication information. And the terminal equipment selects a network according to the first indication information. Through the first indication information, a network with better signal quality can be selected as much as possible, the probability that the terminal equipment always resides in the network with poorer signals is reduced, and the communication quality of the terminal equipment is improved.

Description

Communication method and device

Cross Reference to Related Applications

The present application claims priority of chinese patent application entitled "a communication method, terminal and network device" filed by the chinese intellectual property office on 2021, 03/02/202110230394. X, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to the field of communications technologies, and in particular, to a communication method and device.

Background

Before a terminal device performs a service, it needs to search a network signal, and then select a corresponding Public Land Mobile Network (PLMN) to perform subsequent registration and communication processes in the selected PLMN.

In the process of selecting the PLMN, an access-stratum (AS) layer of the terminal device is responsible for searching for network signals, and a non-access-stratum (NAS) layer of the terminal device is responsible for selecting the PLMN. In the process of selecting the PLMN, the NAS layer preferentially selects a Registered PLMN (RPLMN) that resides in the terminal device last time, that is, the RPLMN is the PLMN that the terminal device has registered last time.

For some internet of things (IoT) devices, they are generally in a static state, and for example, they are fixedly located in a certain area, and the location of them may not be well covered by the network. When an IoT device is registered at a certain time, it is possible that a signal of a certain PLMN can satisfy the requirement of registration, and thus the IoT device is registered to the PLMN. But the signal of the PLMN may be unstable, which results in that the IoT device loses coverage after registration, and the IoT device reselects the network in the absence of coverage. However, in the process of reselecting the network, it is known that the IoT device preferentially stays in the PLMN as described above. This may result in signals of the IoT devices being in a poor state for a long time, affecting communication of the IoT devices.

Disclosure of Invention

The embodiment of the application provides a communication method and equipment, which are used for improving the communication quality of terminal equipment.

In a first aspect, a first communication method is provided, which may be performed by a terminal device, or by a larger device comprising the terminal device, or by a system-on-chip or other functional module, which is capable of performing the functions of the terminal device. The method comprises the following steps: in the process of selecting a network, terminal equipment obtains first indication information, wherein the first indication information is used for indicating that the terminal equipment generates a radio link failure event in the network corresponding to the first indication information; and the terminal equipment selects a network according to the first indication information.

In this embodiment of the present application, if a Radio Link Failure (RLF) event occurs in a certain network, the terminal device may add first indication information to the network. Therefore, when the terminal device selects the network, the terminal device can select the network according to the first indication information, for example, the terminal device can improve the selection threshold, or the terminal device can ignore the network with the first indication information during the selection, so as to select the network with better signal quality as much as possible, reduce the probability that the terminal device always resides in the network with poorer signal, and improve the communication quality of the terminal device.

With reference to the first aspect, in a first optional implementation manner of the first aspect, the method further includes: and the NAS layer of the terminal equipment determines that the first indication information corresponds to a first network, and the first network is a network which is registered by the terminal equipment for the last time. The terminal device selects a network according to the first indication information, for example, selects a network for an AS layer of the terminal device according to the first indication information, or selects a network for an NAS layer of the terminal device according to the first indication information. If the NAS layer of the terminal device selects a network according to the first indication information, the NAS layer of the terminal device may select a network according to the first indication information if it is determined that the first network corresponds to the first indication information. The first network is, for example, any one of the networks to be selected, or the first network is, for example, any one of the networks for which the NAS layer of the UE received the identification from the AS layer of the UE, or the first network is, for example, the network for which the UE has registered last time (e.g., the RPLMN for which the UE has registered last time). According to the existing network selection mode, the UE has a high probability of selecting the RPLMN which is the latest time, and if the signal quality of the RPLMN is poor, the UE can fall into a coverage hole. Therefore, in the embodiment of the present application, the first network is, for example, the RPLMN of the UE last time, and if the RPLMN has the first indication information, the UE may select a network according to the first indication information.

With reference to the first aspect or the first optional implementation manner of the first aspect, in a second optional implementation manner of the first aspect, the selecting, by the terminal device, a network according to the first indication information includes: and the NAS layer of the terminal equipment selects a second network from the networks to be selected according to the first threshold and the first indication information. The NAS layer of the terminal device may select a network according to the first indication information in different manners, for example, one manner is to select a network according to the first threshold and the first indication information.

With reference to the second optional implementation manner of the first aspect, in a third optional implementation manner of the first aspect, the selecting, by the NAS layer of the terminal device, the second network from the networks to be selected according to the first threshold and the first indication information includes: and the NAS layer of the terminal equipment selects the second network from the networks to be selected. The NAS layer of the terminal equipment determines whether a network with the first indication information in the network to be selected is optional according to a first mode, and determines whether a network without the first indication information in the network to be selected is optional according to a second mode; or, the NAS layer of the terminal device determines whether all the networks in the to-be-selected network are selectable according to a first mode; the first mode is related to the first threshold, the second mode is unrelated to the first threshold, and the first threshold is used for the terminal equipment to select a network under the condition that the first indication information exists. It will be appreciated that for networks with first indication information, a first threshold may be additionally introduced to reduce the probability of the UE selecting to a network with poor signal quality. For networks without the first indication information, the UE may not have an RLF event in these networks, and therefore the signal quality of the UE in these networks may not be too poor, and therefore, for these networks, the first threshold may not be additionally introduced, thereby reducing the determination process of the UE and also improving the efficiency of network selection. Or, for all networks to be selected, additionally introducing a first threshold to determine whether the network can be selected. This selection is more rigid and more conducive to selecting a network with better signal quality.

With reference to the first aspect, in a fourth optional implementation manner of the first aspect, the selecting, by the terminal device, a network according to the first indication information includes: and the NAS layer of the terminal equipment selects a second network from the networks to be selected, wherein the networks to be selected comprise the networks without the first indication information. The network with the first indication is the network where the UE has experienced an RLF event, and there may be a risk of poor signaling if the UE selects such a network. Therefore, in this way, when the NAS layer of the UE selects, the network with the first indication information may be ignored, that is, the UE may not select the network with the first indication information. In addition, by the method, the number of the networks which need to be determined whether to be selectable or not when the UE selects the network can be reduced, and the efficiency of selecting the network by the UE can be improved.

With reference to the first aspect or any optional implementation manner of the first aspect to the fourth optional implementation manner of the first aspect, in a fifth optional implementation manner of the first aspect, the obtaining, by the terminal device, the first indication information includes: in the case that a measurement value of a first cell corresponding to a third network is less than or equal to a second threshold, determining, by the AS layer of the terminal device, whether a radio link failure event has occurred at the third network by the terminal device, wherein the terminal device satisfies a cell selection criterion of the first cell; if the terminal device has a radio link failure event in the third network, the AS layer of the terminal device sends, to the NAS layer of the terminal device, a measurement value of the first cell corresponding to the third network and an identifier of at least one network, and sends at least one piece of the first indication information corresponding to the at least one network, where the at least one network includes all networks or part of networks corresponding to the first cell, and the at least one network includes the third network. If the NAS layer of the terminal device selects a network according to the first indication information, the NAS layer of the terminal device may obtain the first indication information from the AS layer of the terminal device. If the measured value of the first cell corresponding to the third network is less than or equal to the second threshold, indicating that the signal quality of the first cell is not good enough, in this case, the AS layer of the terminal device may determine whether an RLF event has occurred in the third network, and if the RLF event has occurred, may send first indication information to the NAS layer of the terminal device, so that the NAS layer of the terminal device specifies which networks the terminal device has occurred in, and thus takes the RLF event into consideration when selecting a network.

With reference to the fifth alternative implementation manner of the first aspect, in a sixth alternative implementation manner of the first aspect, the method further includes: and under the condition that the measured value of the first cell corresponding to the third network is greater than a second threshold, the AS layer of the terminal device sends the identifier of the third network to the NAS layer of the terminal device, and indicates that the third network is a high-quality network. If the measured value of the first cell corresponding to the third network is greater than the second threshold, indicating that the signal quality of the first cell is better, the AS layer of the terminal device may mark the third network AS a high quality network to distinguish it from a network with less good signal quality.

With reference to the first aspect, in a seventh optional implementation manner of the first aspect, the obtaining, by the terminal device, the first indication information includes: in the case that a measurement value of a first cell corresponding to a third network is less than or equal to a second threshold, determining, by the AS layer of the terminal device, whether a radio link failure event has occurred at the third network by the terminal device, wherein the terminal device satisfies a cell selection criterion of the first cell; if the terminal equipment has a radio link failure event in the third network, the AS layer of the terminal equipment obtains the first indication information of the third network. If the AS layer of the terminal device selects a network according to the first indication information, the AS layer of the terminal device can obtain the first indication information according to the mode.

With reference to the seventh optional implementation manner of the first aspect, in an eighth optional implementation manner of the first aspect, the selecting, by the terminal device, a network according to the first indication information includes: and the AS layer of the terminal equipment does not send the identifier of the third network to the NAS layer of the terminal equipment, wherein the identifier of the third network is not sent for the NAS layer of the terminal equipment not to select the third network when selecting the network. If the terminal device has an RLF event in a certain network, the AS layer of the terminal device does not send the identifier of the network to the NAS layer of the terminal device. For the NAS layer of the terminal device, if the identifier of a certain network is not received from the AS layer of the terminal device, the network cannot be selected, and thus the probability that the terminal device selects a network with a poor signal can be reduced.

With reference to the first aspect or any one of the first optional implementation manner of the first aspect to the eighth optional implementation manner of the first aspect, in a ninth optional implementation manner of the first aspect, the method further includes: and after selecting the second network, sending second indication information to the network equipment, wherein the second indication information is used for indicating that the terminal equipment has a radio link failure event in a second cell of a fourth network. After the terminal device successfully selects a certain network, the information of the network and the corresponding cell where the terminal device has an RLF event can be sent to the network device, and the information can be used for network optimization. For example, the network device may increase the camping threshold of the second cell. If the camping threshold is increased, the value of the first parameter that needs to be measured is higher if the terminal device camps in the second cell, which is also equivalent to increasing the difficulty of selecting the second cell by the terminal device, that is, the number of terminal devices that can select the second cell can be reduced. For another example, the network device may configure a first threshold for at least one terminal device, and the difficulty of selecting the second cell by the terminal device may be increased by using the first threshold. And the second cell is a cell in which some terminal devices have RLF, which indicates that the signal quality of the second cell is not good, so that fewer terminal devices select the second cell by increasing the difficulty of selecting the second cell by the terminal device, and the terminal device can reside in the cell with good signal quality as much as possible.

With reference to the first aspect or any one of the first optional implementation manner of the first aspect to the ninth optional implementation manner of the first aspect, in a tenth optional implementation manner of the first aspect, the method further includes: after selecting a second network, sending an identifier of the second network and an identifier of a third cell in which the terminal device is located to network equipment; receiving information of M networks from the network equipment, wherein the M networks are networks in an area where the third cell is located, and M is a positive integer; and searching available networks according to the information of the M networks when the network is selected again. If the terminal device roams into an unfamiliar area, for example, the terminal device performs a blind search in the unfamiliar area. For example, if the terminal device selects the second network through blind search, the terminal device registers to the second network and camps on a third cell under the second network. In this case, the terminal device may send the identity of the second network and the identity of the third cell to the network device via the second network. The network device may determine information of one or more networks in the area where the third cell is located, for example, may determine frequency (frequency band or frequency point) information of one or more networks in the area where the third cell is located, and may send the determined information of these networks to the terminal device. For example, the terminal device is powered off and then powered on, or the terminal device recovers from lack of coverage, or the terminal device performs periodic network selection, the terminal device needs to search for a network again. Then, when the terminal device needs to search for a network, the terminal device may search according to the information of the M networks, for example, the information of the M networks includes frequencies of the M networks, and then the terminal device may search for some or all of the frequencies of the M networks, and for other frequencies except the frequencies of the M networks, the terminal device may not search any more, or the number of searched frequencies may be reduced.

With reference to the first aspect or any one of the first to the tenth optional embodiments of the first aspect, in an eleventh optional embodiment of the first aspect, the first network is a PLMN or an NPN. The embodiment of the present application does not limit the concept of "network".

In a second aspect, a second communication method is provided, which may be performed by a network device, or by a system-on-chip or other functional module, which is capable of implementing the functionality of the network device. Illustratively, the network device is an access network device, such as a base station. The method comprises the following steps: receiving second indication information from a terminal device, wherein the second indication information is used for indicating that the terminal device has a radio link failure event in a second cell of a fourth network; executing a first processing mode; wherein, the first processing mode comprises the following steps: reconfiguring a cell selection criterion for the second cell; and/or configuring a first threshold for at least one terminal device, wherein the first threshold is used for the terminal device to determine whether the second cell can be selected.

With reference to the second aspect, in a first optional implementation manner of the second aspect, the method further includes: receiving, from the terminal device, an identity of a second network and an identity of a third cell in which the terminal device is located; and sending information of M networks to the terminal equipment, wherein the M networks are networks in the area where the third cell is located, and M is a positive integer.

With regard to the technical effects brought about by the second aspect or various alternative embodiments, reference may be made to the introduction of the technical effects of the first aspect or the respective embodiments.

In a third aspect, a third communication method is provided, which may be performed by a network device, or by a system-on-chip or other functional module, which is capable of implementing the functionality of the network device. Illustratively, the network device is an access network device, such as a base station. The method comprises the following steps: receiving an identifier of a second network and an identifier of a third cell in which the terminal device is located from the terminal device; and sending information of M networks to the terminal equipment, wherein the M networks are networks in the area where the third cell is located, and M is a positive integer.

With reference to the third aspect, in a first optional implementation manner of the third aspect, the method further includes: receiving second indication information from a terminal device, wherein the second indication information is used for indicating that the terminal device has a radio link failure event in a second cell of a fourth network; executing a first processing mode; wherein the first processing mode comprises the following steps: reconfiguring a cell selection criterion for the second cell; and/or configuring a first threshold for at least one terminal device, wherein the first threshold is used for the terminal device to determine whether the second cell can be selected.

With regard to the technical effects brought about by the third aspect or the various alternative embodiments, reference may be made to the introduction of the technical effects of the first aspect or the respective embodiments.

In a fourth aspect, a communication device is provided. The communication device may be the terminal apparatus according to any one of the first to third aspects. The communication device has the functions of the terminal equipment. The terminal device is, for example, a base station or a baseband device in the base station. In an alternative implementation, the communication device includes a baseband device and a radio frequency device. In another alternative implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). The transmitting/receiving unit can implement a transmitting function and a receiving function, and when the transmitting/receiving unit implements the transmitting function, it can be referred to as a transmitting unit (also referred to as a transmitting module in some cases), and when the transmitting/receiving unit implements the receiving function, it can be referred to as a receiving unit (also referred to as a receiving module in some cases). The sending unit and the receiving unit can be the same functional module, the functional module is called as a receiving and sending unit, and the functional module can realize the sending function and the receiving function; alternatively, the transmitting unit and the receiving unit may be different functional modules, and the transmitting and receiving unit is a general term for these functional modules.

The processing unit is configured to obtain first indication information in a process of selecting a network, where the first indication information is used to indicate that a radio link failure event occurs in a network corresponding to the first indication information by the terminal device;

the processing unit is further configured to select a network according to the first indication information.

In an optional implementation manner, the communication apparatus further includes a storage unit, and the processing unit is configured to couple with the storage unit and execute a program or an instruction in the storage unit, so as to enable the communication apparatus to perform the function of the terminal device according to any one of the first to third aspects.

In a fifth aspect, a communications apparatus is provided. The communication device may be the network apparatus according to any one of the first to third aspects. The communication device has the functions of the network equipment. The network device is, for example, a base station or a baseband apparatus in a base station. In an alternative implementation, the communication device includes a baseband device and a radio frequency device. In another alternative implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). Reference is made to the introduction of the fourth aspect for an implementation of the transceiver unit.

The transceiver (or the receiver) is configured to receive second indication information from a terminal device, where the second indication information is used to indicate that the terminal device has a radio link failure event in a second cell of a fourth network; the processing unit is used for executing a first processing mode. The first processing mode comprises the following steps: reconfiguring a cell selection criterion for the second cell; and/or configuring a first threshold for at least one terminal device, wherein the first threshold is used for the terminal device to determine whether the second cell can be selected.

Or, the transceiver unit (or the receiving unit) is configured to receive, from a terminal device, an identifier of a second network and an identifier of a third cell in which the terminal device is located; the transceiver unit (or the transmitter unit) is configured to send information of M networks to the terminal device, where the M networks are networks in an area where the third cell is located, and M is a positive integer.

In an alternative implementation manner, the communication apparatus further includes a storage unit, and the processing unit is configured to couple with the storage unit and execute a program or an instruction in the storage unit, so as to enable the communication apparatus to perform the function of the network device according to any one of the first to third aspects.

A sixth aspect provides a computer-readable storage medium for storing a computer program or instructions which, when executed, cause the method performed by the terminal device or the network device in the above aspects to be implemented.

In a seventh aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the method of the above aspects to be carried out.

Drawings

Fig. 1 is a schematic view of an application scenario according to an embodiment of the present application;

fig. 2 to 4 are flowcharts of several communication methods provided in the embodiments of the present application;

fig. 5 is a schematic block diagram of a communication device provided in an embodiment of the present application;

fig. 6 is a schematic block diagram of a terminal device provided in an embodiment of the present application;

fig. 7 is a schematic block diagram of a network device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

Hereinafter, some terms or concepts in the embodiments of the present application will be explained so as to be easily understood by those skilled in the art.

In the embodiment of the present application, the terminal device is a device having a wireless transceiving function, and may be a fixed device, a mobile device, a handheld device (e.g., a mobile phone), a wearable device, an in-vehicle device, or a wireless apparatus (e.g., a communication module, a modem, or a chip system, etc.) embedded in the above device. The terminal equipment is used for connecting people, objects, machines and the like, and can be widely used in various scenes, such as but not limited to the following scenes: cellular communication, device-to-device communication (D2D), vehicle-to-all (V2X), machine-to-machine/machine-type communication (M2M/MTC), internet of things (IoT), Virtual Reality (VR), Augmented Reality (AR), industrial control (industrial control), unmanned driving (self driving), remote medical (remote medical), smart grid (smart grid), smart furniture, smart office, smart wearing, smart transportation, smart city (smart city), unmanned aerial vehicle, robot, etc. scenarios. The terminal equipment may sometimes be referred to as User Equipment (UE), a terminal, an access station, a UE station, a distant station, wireless communication equipment, or user equipment, among others. For convenience of description, in the embodiments of the present application, a terminal device is described by taking a UE as an example.

The network device in the embodiment of the present application includes, for example, one or more of the following: access network equipment, core network equipment, or a server set by an operator. The access network equipment is equipment with a wireless transceiving function and is used for communicating with the terminal equipment. The access network device includes, but is not limited to, a base station (BTS, Node B, eNodeB/eNB, or gbnodeb/gNB), a Transmission Reception Point (TRP) in the above communication system, a base station for subsequent evolution of the third generation partnership project (3 GPP), an access Node in a wireless fidelity (Wi-Fi) system, a wireless relay Node, a wireless backhaul Node, and the like. The base station may be: macro base stations, micro base stations, pico base stations, small stations, relay stations, etc. Multiple base stations may support the same access technology network mentioned above, or may support different access technologies networks mentioned above. A base station may include one or more co-sited or non-co-sited transmission receiving points. The network device may also be a wireless controller, a Centralized Unit (CU), and/or a Distributed Unit (DU) in a Cloud Radio Access Network (CRAN) scenario. The network device may also be a server, a wearable device, or a vehicle mounted device, etc. For example, the network device in vehicle to everything (V2X) technology may be a Road Side Unit (RSU). The following description will take the access network device as a base station as an example. The base station may communicate with the terminal device, and may also communicate with the terminal device through the relay station. A terminal device may communicate with multiple base stations in different access technologies. The core network equipment is used for realizing the functions of mobile management, data processing, session management, policy, charging and the like. The names of devices for implementing the core network function in systems with different access technologies may be different, and this is not limited in this embodiment of the present application. Taking a 5G system as an example, the core network device includes: an access and mobility management function (AMF), a Session Management Function (SMF), a Policy Control Function (PCF), or a User Plane Function (UPF), etc. A server set by a carrier may be used to manage one or more types of terminal devices, for example, an IoT device manager (IoT device manager) as a type of server set by the carrier may manage IoT devices covered by the carrier.

In the embodiment of the present application, the communication device for implementing the function of the network device may be a network device, or may be a device capable of supporting the network device to implement the function, for example, a system on chip, and the device may be installed in the network device. In the technical solution provided in the embodiment of the present application, a device for implementing a function of a network device is taken as an example, and the technical solution provided in the embodiment of the present application is described.

In the embodiments of the present application, the number of nouns means "singular nouns or plural nouns" or "one or more" unless otherwise specified. "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. For example, A/B, represents: a or B. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, represents: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b and c can be single or multiple.

In the embodiments of the present application, the ordinal numbers such as "first", "second", and the like are used to distinguish a plurality of objects, and are not used to limit the size, content, order, timing, priority, importance, or the like of the plurality of objects. For example, the first network and the second network may be the same network or different networks, and such names do not indicate differences in the locations, corresponding parameters, priorities, importance levels, and the like of the two networks. In addition, the numbering of the steps in each embodiment described in the present application is only for distinguishing different steps, and is not used for limiting the sequence of the steps. For example, S201 may occur before S202, or may occur after S202, or may also occur simultaneously with S202.

In the process of selecting the PLMN, the AS layer of the UE is responsible for searching network signals, and the NAS layer of the UE is responsible for selecting the PLMN.

The AS layer of the UE mainly performs a cell search procedure. The AS layer searches cells on some frequency points, and for one searched cell, if the broadcast information of the cell can be read, the AS layer can acquire the cell selection standard included in the broadcast information and acquire the information of the PLMN corresponding to the cell. The broadcast information for a cell includes cell selection criteria that includes conditions to be met for selecting the cell. For example, the UE determines whether the cell is allowed to camp (i.e., determines whether the cell is in a barred (bar) state, if the cell is in the bar state, the cell is not allowed to camp, otherwise the cell is allowed to camp), if the cell is allowed to camp, the UE determines whether the measured Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the UE at the cell are greater than a threshold provided by a System Information Block (SIB) of the cell, the SIB is, for example, SIB1, if the measured RSRP and RSRQ of the UE at the cell are greater than the threshold provided by the SIB of the cell, the UE may select the cell, otherwise the UE may not select the cell. That is, by the cell selection criterion, it can be determined whether the signal quality of the cell is good enough to support the UE camping on the cell.

For a cell for which the UE satisfies the cell selection criterion, if the signal strength of the cell is higher than a threshold (e.g., -110dBm in a Long Term Evolution (LTE) system, a NR system, or a narrowband internet of things (NB-IoT)) system, the AS layer marks a PLMN corresponding to the cell AS a high quality PLMN (HQ PLMN), and sends the PLMN ID and the label of the HQ PLMN to the NAS layer. For a cell of which the UE satisfies the cell selection criterion, if the signal strength of the cell is lower than the threshold, the AS layer may send the PLMN ID corresponding to the cell and the RSRP of the cell to the NAS layer, where the RSRP of the cell is the RSRP measured by the UE in the cell. If the UE does not satisfy the cell selection criterion of a cell, the AS layer of the UE does not need to report information of the PLMN corresponding to the cell (for example, an identifier of the PLMN corresponding to the cell, etc.) to the NAS layer of the UE.

The NAS layer of the terminal device may trigger the NAS layer to select the PLMN in two cases: the first case is power-on or recovery from lack of coverage, and the second case is periodic network selection attempts. The first case may be understood as the need to find a suitable PLMN access when the UE is powered on or after recovering from a lack of coverage condition. The second case is for the UE to select a PLMN according to the operator configuration, and the UE needs to periodically search to determine whether there is a higher priority PLMN. The network selection process for these two cases is described separately below.

1. In the first case, the network selection process.

The NAS layer of the UE typically searches for the RPLMN when it starts selecting a PLMN, and after finding the RPLMN, the NAS layer determines whether the RPLMN is available (or optional). It was introduced in the foregoing that the AS layer of the UE reports some PLMN IDs to the NAS layer, and if the NAS layer receives a certain PLMN ID from the AS layer, whether the PLMN has an HQ PLMN flag or does not have an HQ PLMN flag, it indicates that the PLMN is available. The NAS layer can determine whether the RPLMN is available or not in this way, and if the RPLMN is available, the NAS layer selects the RPLMN to reside without making other judgment. If the RPLMN is not available, the NAS layer may traverse the following list in order of priority: an (equivalent) home PLMN list (HPLMN list), a User Controlled PLMN Selector with Access Technology (User Controlled PLMN Selector with Access Technology) list with Access Technology, an operation Controlled PLMN Selector with Access Technology (Operator Controlled PLMN Selector with Access Technology) list with Access Technology. These lists may be pre-configured in a Subscriber Identity Module (SIM) card by the operator, or the operator may issue the lists to the UE after the UE enters the network, or the operator may send updated information of the lists to the UE after the UE enters the network. Wherein the (equivalent) HPLMN list includes information of the HPLMN of the UE, and/or includes information of an equivalent PLMN of the HPLMN of the UE. The equivalent PLMNs of the HPLMN of the UE are, for example, some PLMNs configured by an operator of the HPLMN, for example, the operator of the HPLMN has a contract with an operator to which the PLMNs belong, and then the PLMNs may be the equivalent PLMNs of the HPLMN. The User Controlled PLMN Selector with Access Technology list is a User configured Access PLMN list, which includes information of some User configured PLMNs. Operator Controlled PLMN Selector with Access Technology list is an Operator configured Access PLMN list comprising information of some PLMNs configured by the Operator.

The NAS layer determines in turn whether PLMNs as listed above are available in order of priority. For example, for a PLMN in a list, the NAS layer may determine whether the PLMN is available, and the determination may be made as described above. If the PLMN is determined to be available, the NAS layer may select the PLMN without making subsequent determinations. If all PLMNs in the lists are unavailable, the NAS layer selects according to the information reported by the AS layer. For example, the PLMN ID reported by the AS layer includes a PLMN ID marked by an HQ RPLMN, and the NAS layer may select a PLMN corresponding to one PLMN ID from the PLMN IDs for residing. And if the PLMN ID reported by the AS layer does not comprise the PLMN ID marked by the HQ RPLMN, the NAS layer sorts the PLMN ID according to the RSRP corresponding to each PLMN ID reported by the AS layer, and the PLMN corresponding to the PLMN ID with the highest RSRP value can be selected for residing.

In this case, the RPLMN, the PLMNs in the list above, and the PLMN whose ID was reported by the AS layer are all considered to be the PLMN to be selected.

2. And in the second case, the network selection process.

The NAS layer of the UE may maintain a HPLMN control timer, and upon expiration of the timer, the NAS layer may scan for high priority PLMNs, i.e., the UE may periodically scan for high priority PLMNs to determine whether the high priority PLMNs can be accessed. In the second case, the NAS layer would not prioritize the RPLMN, but would traverse the following list in priority order: (priority) HPLMN list, User Controlled PLMN Selector with Access Technology List, Operator Controlled PLMN Selector with Access Technology List. For example, for a PLMN in a list, the NAS layer may determine whether the PLMN is available, and the determination may be made as described above. If the PLMN is determined to be available, the NAS layer may select the PLMN without making subsequent determinations. And if all PLMNs in these lists are not available, the UE continues to camp on the RPLMN. In this case, both the RPLMN and the PLMN in the list above are considered to be the PLMN to be selected.

Although the NAS layer does not give priority to the RPLMN in this case, it is highly likely that the ID of the RPLMN exists in one or more of the above lists, and then the UE may actually consider whether it resides in the RPLMN when traversing the above lists. That is, in the second case, there is a high probability that the UE will continue to camp on the RPLMN.

Currently, the same network selection method is adopted for UEs with lower capability such as IoT and the like. In some regions (e.g., europe), some low-cost low-capability IoT UEs typically have the following characteristics:

these UEs are often in a stationary state;

these UEs may be located in remote locations with limited coverage;

the UEs need stable data connection as a part of the measurement and control network, and the UEs do not necessarily transmit small data volume;

these UEs may be distributed anywhere in the world.

For example, IoT UEs may be placed at the water bottom in a reservoir, which may be placed at the water bottom to monitor water levels, and may send information related to water levels to the network periodically or upon event triggers.

For some IoT UEs, permanent roaming may be employed, i.e., there is typically no HPLMN at the time of access. But these IoT UEs still have RPLMNs since they will still register to a certain Visited PLMN (VPLMN). Such IoT UEs encounter some problems in deployment. For example, after an IoT UE registers to a certain PLMN, the signal of the PLMN may be unstable, so that the IoT UE loses coverage after registration, and subsequent data transmission of the IoT UE may fail. The IoT UE may reselect to the network in the absence of coverage, and as described above, the IoT UE will prefer to camp on the RPLMN even if there is a better network. This may result in signals of the IoT UE being in a poor state for a long time, affecting communication of the IoT UE.

The lot of IoT UEs may be in a large number, and if more lot of IoT UEs are in this state, the lot of IoT UEs may need additional maintenance, and this maintenance may need manual processing in the field, which increases the complexity of maintenance, and also causes the operator to pay higher operation cost, which reduces the business benefit of machine to machine (M2M).

In view of this, the technical solutions of the embodiments of the present application are provided. In the embodiment of the present application, if a communication failure occurs in a certain network by a terminal device, for example, an RLF event occurs, first indication information may be added to the network. Therefore, when the NAS layer of the terminal device selects a network, the NAS layer may select according to the first indication information, for example, the terminal device may increase a selection threshold, or the terminal device may ignore the network with the first indication information when selecting, so as to select a network with better signal quality as much as possible, reduce the probability that the terminal device always resides in a network with poorer signal, and improve the communication quality of the terminal device.

Fig. 1 is a schematic view of an application scenario according to an embodiment of the present application. In fig. 1, the UE is able to communicate with network device 1, and cell 1 provided by network device 1 is a cell covered by PLMN1, for example, PLMN1 is the RPLMN and/or HPLMN of the UE. In addition, the cell 2 provided by the network device 2 is a neighboring cell of the UE, and is a cell covered by the PLMN 2. It can be seen that the UE is at the edge of cell 1, and the coverage of the UE by PLMN1 may not be good, e.g., the UE may lose the coverage of PLMN1, and the UE may reselect to the PLMN. Or even if the UE does not lose coverage, the UE may select a PLMN if it is just powered on, or the UE may periodically select a PLMN. When the UE selects a PLMN, both PLMN1 and PLMN2 may be within a selectable range.

The network device in fig. 1 is, for example, an access network device, and the access network device is, for example, a base station. The access network device corresponds to different devices in different systems, for example, in a 4G system, the access network device may correspond to an eNB, and in a 5G system, the access network device in a 5G system, for example, a gNB. Of course, the technical solution provided in the embodiment of the present application may also be applied to a future mobile communication system, and therefore, the access network device in fig. 1 may also correspond to a network device in the future mobile communication system. In the embodiment of the present application, the access network device is taken as a base station as an example, and actually, with reference to the foregoing description, the access network device may also be a device such as an RSU.

The method provided by the embodiment of the application is described below with reference to the accompanying drawings. In the figures corresponding to the various embodiments of the present application, all optional steps are indicated with dashed lines. The UE described in the embodiments of the present application is, for example, an IoT UE, or may also be a normal UE. The "network" described in the embodiments of the present application may be, for example, a PLMN or a non-public network (NPN), or may also be other networks, for example, the first network is a first PLMN or a first NPN, and the second network is a second PLMN or a second NPN, etc.; the network (e.g., RPLMN) to which the UE has registered last time according to the various embodiments of the present application is, for example, PLMN1 in the network architecture shown in fig. 1; the technical solutions described in the embodiments of the present application can be applied to the network architecture shown in fig. 1. For example, the UE described in the embodiments of the present application is, for example, the UE in the network architecture shown in fig. 1.

It should be noted that, in the following description, operations of the UE, such AS searching for a cell, reading system information of the cell, determining whether a network corresponding to the cell is a high quality network, or determining whether the UE has an RLF event in the network corresponding to the cell, are performed by using an AS layer of the UE, but are not limited to this in practical application, and for example, the operations may be performed by other protocol layers of the UE, and in addition, the operations may be performed by one protocol layer or by multiple protocol layers. Similarly, the other operations of the UE, such as selecting a network, described in the embodiments of the present application are performed by using the NAS layer of the UE as an example, but the present invention is not limited to this in practical application, and for example, the operations may be performed by another protocol layer of the UE, and the operations may be performed by one protocol layer or by multiple protocol layers.

An embodiment of the present application provides a communication method, please refer to fig. 2, which is a flowchart of the method.

S201, when selecting a network, the AS layer of the UE searches a cell in the designated frequency band. For example, the AS layer of the UE may perform a full frequency search in a frequency band (band)1 at a frequency interval, e.g., 100kHz or 10 kHz. The network selection is, for example, a periodic selection, or a selection when the UE is powered on, or a selection after the UE recovers in lack of coverage.

S202, if the cell is searched by the AS layer of the UE, the system information of the cell can be read.

For example, the AS layer of the UE searches for the first cell, and may read system information of the first cell, where the system information includes, for example, system information block 1 (SIB 1). The SIB1 may include a cell selection criterion of the first cell that may indicate a condition that the UE needs to satisfy to select the first cell, e.g., the cell selection criterion of the first cell includes a camping threshold that the UE needs to reach to select the first cell. Additionally, the SIB1 may also include an identification of the network to which the first cell corresponds, such as an identity number of the network, and the first cell may correspond to one or more networks. The identity number of the network includes, for example, an ID of the network (for example, if the network is a PLMN, the identity number of the network includes an ID of the PLMN, or if the network is a stand-alone non-public network (SNPN), the identity number of the network includes an ID of the SNPN), or includes a Closed Access Group (CAG) ID of the network, or includes a human-readable network name (HRNN) of the network, and the like.

S203, the AS layer of the UE determines whether the UE satisfies the cell selection criterion of the first cell. If the AS layer of the UE determines that the UE satisfies the cell selection criterion of the first cell, S204 may be performed, and if the AS layer of the UE determines that the UE does not satisfy the cell selection criterion of the first cell, S201 may be continuously performed.

S204, the AS layer of the UE determines whether the measured value of the first cell corresponding to the third network is greater than a second threshold. S205 is performed if the measured value of the first cell corresponding to the third network is greater than the second threshold, and S207 is performed if the measured value of the first cell corresponding to the third network is less than or equal to the second threshold.

The measurement value of the first cell is, for example, a value of a first parameter obtained by measuring, by an AS layer of the UE, a reference signal from the first cell, and the first parameter may indicate signal quality of the UE, for example, the first parameter is RSRP or RSRQ. It was introduced in the foregoing that the first cell may correspond to one or more networks and the third network is for example any one of the networks corresponding to the first cell. If the first cell corresponds to multiple networks, the UE may measure reference signals from different networks separately in the first cell, and may obtain measurements corresponding to different networks in the first cell. Since the UE processes the measurement values of different networks in a similar manner, the measurement value corresponding to the third network measured by the UE in the first cell is taken as an example for description.

The second threshold is, for example, a threshold specified by a protocol, or a threshold configured by the network device, or a threshold determined by the UE itself. For example, in an LTE system, an NR system, or an NB-IoT system, the second threshold is-110 dbm, or may be other values.

S205, if the measured value of the first cell corresponding to the third network is greater than the second threshold, the AS layer of the UE marks the third network AS a High Quality (HQ) network.

Optionally, the AS layer of the UE may determine whether the UE has experienced an RLF event in the third network. That is, although the third network is currently a high quality network, the UE may determine whether the RLF event occurred in the third network. There may be several ways of subscribing as to whether the UE has experienced an RLF event in the third network, as will be described in subsequent steps.

S206, the AS layer of the UE sends the identifier of the third network to the NAS layer of the UE, and indicates that the third network is a high-quality network (for example, the AS layer of the UE sends high-quality indication information to the NAS layer of the UE, and the high-quality indication information may indicate that the network corresponding to the second indication information is the high-quality network). The identification of the third network is, for example, an ID of the third network.

Optionally, if the AS layer of the UE determines that the UE has an RLF event in the third network, in S206, the AS layer of the UE may send, in addition to sending the identifier of the third network to the NAS layer of the UE and indicating that the third network is a high-quality network, first indication information to the NAS layer of the UE, where the first indication information may indicate that the UE has an RLF event in a network corresponding to the first indication information. When the NAS layer of the UE receives the first indication information (it is also considered that the NAS layer of the UE has acquired the first indication information), it may be determined that the RLF event has occurred in the third network.

For example, if the identity of a certain network sent by the AS layer of the UE to the NAS layer of the UE corresponds to the first indication information, the RLF event of the UE in the network may be indicated, and if the identity of the certain network sent by the AS layer of the UE to the NAS layer of the UE does not correspond to the first indication information, the RLF event of the UE in the network may be indicated. For another example, if the identity of a certain network sent by the AS layer of the UE to the NAS layer of the UE corresponds to the first indication information, it may indicate that the UE has not experienced the RLF event in the network, and if the identity of a certain network sent by the AS layer of the UE to the NAS layer of the UE does not correspond to the first indication information, it may indicate that the UE has experienced the RLF event in the network.

Or, the identities of the networks sent by the AS layer of the UE to the NAS layer of the UE may all correspond to the first indication information, and the first indication information may indicate that the RLF event has occurred in the network by the UE, or indicate that the RLF event has not occurred in the network by the UE. For example, the first indication information occupies 1 bit (bit), if the bit takes the value of "1", it indicates that the UE has an RLF event in the network, and if the bit takes the value of "0", it indicates that the UE has not an RLF event in the network.

Of course, other implementations of the first indication information are within the scope of the embodiments of the present application.

S207, if the measured value of the first cell corresponding to the third network is less than or equal to the second threshold, the AS layer of the UE determines whether the UE has RLF event in the third network.

If the UE satisfies the cell selection criterion of the first cell, but a measurement value of the UE measured for a reference signal from the third network at the first cell is less than or equal to a second threshold, and the AS layer of the UE is able to read the identity of the third network, the AS layer of the UE may determine whether the UE has experienced an RLF event at the third network. There are several ways that the UE may recognize if an RLF event has occurred in the third network, as described below by way of example.

As an optional embodiment, if the UE has RLF events occurred in the third network for X times within the first time duration, it is determined that the UE has RLF events in the third network, and if the number of RLF events occurred in the third network for the first time duration is less than X, it is determined that the UE has not RLF events in the third network. X is a positive integer, and if X is greater than 1, X times are, for example, consecutive X times, or may be discontinuous X times. The ending time of the first duration is, for example, the current time, and the duration or starting time of the first duration is, for example, specified by a protocol, or configured by the network device, or determined by the UE itself. For example, one starting time of the first duration is the time when the UE is turned on last time; for another example, another starting time of the first duration is a time when the UE has last registered with the third network; for another example, another starting time of the first duration is a time when the UE initially registers to the third network.

As another optional embodiment, if the RLF event occurs in the third network after the UE initially registers in the third network, it is determined that the RLF event occurs in the third network, and if the RLF event does not occur in the third network after the UE initially registers in the third network, it is determined that the RLF event does not occur in the third network. The RLF event occurs in the third network after the UE initially registers with the third network, and the RLF event may be successfully recovered or may not be successfully recovered, and an event that triggers the UE to perform network selection this time may be the RLF event or may not be the RLF event. That is, as long as the RLF event occurs in the third network after the UE initially registers in the third network, the RLF event is considered to have occurred in the third network regardless of the recovery result of the RLF event and regardless of whether the RLF event is an event that triggers the network selection of this time.

Through the above two embodiments, it is possible to determine the network where the UE has historically experienced the RLF event, and since the UE has historically experienced the RLF event in the third network, which indicates that there is a risk of the UE having a problem in the communication in the third network, screening such a network helps to reduce the probability that the UE will again experience the RLF event.

As another alternative, if the RLF event occurs in the third network and the RLF event recovery fails, it is determined that the RLF event occurs in the third network, otherwise, if the RLF event occurs in the third network but the RLF event recovery succeeds, it is determined that the RLF event has not occurred in the third network. Wherein, if the RLF event recovery fails, the RLF event may be an event that triggers the network selection. In the embodiment, the network with the RLF event is screened according to the current situation, and the current situation can more accurately reflect the current quality of the network, so that the selection range of the UE is expanded under the condition of ensuring the communication quality of the UE as much as possible.

It is noted that the UE described in the introduction of the various embodiments above has an RLF event at the third network, which RLF event may occur at the first cell or at a cell other than the first cell.

As still another optional implementation, if the first cell in the third network is an alternative cell of the third network, if the UE has an RLF event in a cell other than the first cell covered by the third network, the UE may also be considered as having no RLF event in the third network, and if the UE has an RLF event in the first cell covered by the third network, the UE may be considered as having an RLF event in the third network. That is, in this case, the UE considers that an RLF event has occurred in a network only if the RLF event has occurred in an alternative cell of the network. In this embodiment, if one network can provide multiple cells, the network having RLF events can be more accurately screened according to the current situation, and the current situation can more accurately reflect the current quality of the network, so as to expand the selection range of the UE while ensuring the communication quality of the UE as much as possible.

S208, the AS layer of the UE determines whether the measured value of the third network is larger than a third threshold.

Optionally, for a network whose measurement value is less than or equal to the second threshold and the RLF event occurs in the UE, a screening mechanism of the AS layer of the UE (hereinafter, also referred to AS a screening mechanism of the AS layer) may be introduced. If the AS layer screening mechanism is introduced, after performing S207, if the UE determines that an RLF event has occurred in the third network, S208 may be performed, and if the UE determines that an RLF event has not occurred in the third network, S208 may not be performed but S209 may be performed instead. Alternatively, if no screening mechanism of the AS layer is introduced, after performing S207, no matter whether the UE has an RLF event in the third network, S208 does not have to be performed, but S209 is performed.

For example, if the UE considers that the RLF event occurs in the network only if the RLF event occurs in the candidate cell of a certain network, if the first cell is a candidate cell of a third network and the UE is that the RLF event occurs in the first cell, the AS layer of the UE may determine whether the measurement value of the first cell is greater than a third threshold in S208. For another example, if the UE determines that the UE has an RLF event in the third network in other manners introduced above, in S208, the AS layer of the UE may determine whether a measurement value of any cell under the third network coverage of the UE is greater than a third threshold, or the AS layer of the UE may determine whether a measurement value of a cell under the third network coverage of the UE having an RLF event is greater than a third threshold. The third threshold is specified by a protocol, or configured by a network device, or may be determined by the UE itself, or configured in a Subscriber Identity Module (SIM) card or a Universal Subscriber Identity Module (USIM) card, for example. The third threshold is the same as the first threshold described later, for example, the value may be the same, or the value may be different.

If the screening mechanism of the AS layer is introduced and S208 is performed, if the UE determines that the measurement value of the third network is greater than the third threshold, S209 may be continuously performed, and if the UE determines that the measurement value of the third network is less than or equal to the third threshold, S209 may not be performed, but S201 may be continuously performed, that is, the UE continues to search for other cells and determines networks corresponding to the other cells in a similar manner AS described above. Equivalently, if a screening mechanism of the AS layer is introduced, the AS layer equivalent to the UE further screens the networks where the RLF event occurs by introducing a third threshold, so AS to report the networks with better signal quality to the NAS layer of the UE for selection, and for the networks with poorer signal quality (for example, the networks with the measurement value less than or equal to the third threshold), the AS layer of the UE may not report to the NAS layer of the UE, and the NAS layer of the UE may not select these networks. This further helps the UE to select to the network with better signal quality and reduces the workload of the NAS layer of the UE.

S209, the AS layer of the UE sends the measurement value of the first cell corresponding to the third network and the identification of at least one network to the NAS layer of the UE. The at least one network includes all or part of the network corresponding to the first cell, and the third network is one of the at least one network.

S205 to S206 and S207 to S209 are two parallel schemes, and one of them may be executed according to the magnitude relationship between the measurement value of the first cell corresponding to the third network and the second threshold.

If a screening mechanism of the AS layer is introduced, the AS layer of the UE may perform S209 if it is determined that the UE has not performed the RLF event in the third network, and in S209, the AS layer of the UE may send an identification of the third network to the NAS layer of the UE and send a measurement value corresponding to the third network obtained by the UE in the first cell. At this time, at least one network is a third network. For example, if the third network is a PLMN, the AS layer of the UE sends the ID of the PLMN to the NAS layer of the UE, and sends RSRP or RSRQ corresponding to the PLMN, which is measured by the UE in the first cell.

If no screening mechanism of the AS layer is introduced, if the AS layer of the UE determines that the UE has not experienced an RLF event in the third network, the AS layer of the UE may send the identity of the third network to the NAS layer of the UE and send the measurement value corresponding to the third network obtained by the UE in the first cell in S209. At this time, at least one network is a third network. For example, if the third network is a PLMN, the AS layer of the UE sends the ID of the PLMN to the NAS layer of the UE, and sends RSRP or RSRQ corresponding to the PLMN, which is measured by the UE in the first cell.

If the screening mechanism of the AS layer is not introduced, if the AS layer of the UE determines that the UE has an RLF event in the third network, in S209, the AS layer of the UE may send an identifier of at least one network to the NAS layer of the UE, and send a measurement value corresponding to the third network obtained in the first cell by the UE. The first indication information may indicate that the UE has an RLF event in the network corresponding to the first indication information, and reference may be made to the foregoing description for implementation of the first indication information. When the NAS layer of the UE receives the at least one first indication (it is also considered that the NAS layer of the UE has obtained the first indication, or that the NAS layer of the UE has obtained the at least one first indication), it may be determined that the RLF event occurs in the at least one network by the UE. For example, the AS layer of the UE sends the first indication information of the third network to the NAS layer of the UE, so that the NAS layer of the UE can clarify that the RLF event occurs in the third network. For example, if the first cell corresponds to multiple networks, and one of the multiple networks is a third network, because the UE temporarily determines that the UE has an RLF event in the third network and does not involve other networks corresponding to the first cell, the AS layer of the UE may simply send the identity of the third network to the NAS layer of the UE without sending the identities of the other networks. Or, if the first cell corresponds to multiple networks, and one of the multiple networks is a third network, because the RLF event occurs in the third network by the UE, if the RLF event occurs in the first cell, it is also possible that the RLF event occurs (or occurs) in another network corresponding to the first cell by the UE, so the AS layer of the UE may send, to the NAS layer of the UE, an identifier of all networks or a part of networks corresponding to the first cell (the identifier sent by the UE includes an identifier of the third network).

If the AS layer of the UE simply sends the identifier of the third network to the NAS layer of the UE, in S209, the AS layer of the UE may send the measurement value of the first cell corresponding to the third network, the identifier of the third network, and the first indication information corresponding to the third network to the NAS layer of the UE. Alternatively, if the AS layer of the UE sends the NAS layer of the UE the identity of all networks or part of networks corresponding to the first cell, the AS layer of the UE may send, in S209, the measurement value of the first cell corresponding to the third network, the identity of the at least one network, and the at least one first indication information corresponding to the at least one network to the NAS layer of the UE.

S210, the UE obtains first indication information.

S210 may be regarded AS the AS layer of the UE obtaining the first indication information, and may also be regarded AS the NAS layer of the UE obtaining the first indication information. If S210 is regarded AS the AS layer of the UE obtaining the first indication information, in S205 if the AS layer of the UE determines whether the UE has an RLF event in the third network and the determination result is that the UE has an RLF event in the third network, the AS layer of the UE is regarded AS obtaining the first indication information, and this step in S205 can be regarded AS being included in S210. Similarly, if the AS layer of the UE determines whether the UE has an RLF event in the third network in S207, and the determination result is that the UE has an RLF event in the third network, the AS layer of the UE is considered to obtain the first indication information, and this step in S207 can be considered to be included in S210.

If S210 is regarded AS the NAS layer of the UE to obtain the first indication information, for example, the NAS layer of the UE may receive the first indication information from the AS layer of the UE through S209 and may also receive the first indication information from the AS layer of the UE through S206, and the NAS layer of the UE receives the first indication information from the AS layer of the UE, the NAS layer of the UE is regarded AS obtaining the first indication information, for example, the NAS layer of the UE may obtain one or more first indication information. In addition, if the AS layer of the UE transmits the first indication information corresponding to the third network to the NAS layer of the UE in S206, the NAS layer of the UE receives the first indication information corresponding to the third network from the AS layer in S206, which is considered to be included in S210. Similarly, if the AS layer of the UE sends the at least one first indication information to the NAS layer of the UE in S209, the NAS layer of the UE receives the at least one first indication information from the AS layer in S209, which is considered to be included in S210. In addition, all the steps of receiving the first indication information from the AS layer of the UE by the NAS layer of the UE are considered to be included in S210.

S211, the UE selects a network according to the first indication information.

S211 may be regarded AS the AS layer of the UE selecting a network according to the first indication information, and may also be regarded AS the NAS layer of the UE selecting a network according to the first indication information. If S211 is regarded AS the AS layer of the UE selecting a network according to the first indication information, then in S205, if the AS layer of the UE determines whether the UE has an RLF event at the third network and S206 is performed, the AS layer regarded AS the UE selects a network according to the first indication information. That is, this option is that if the third network is a high quality network, the AS layer of the UE may send information related to the third network (e.g., an identity of the third network, etc.) to the NAS layer of the UE regardless of whether the RLF event occurs in the third network. Similarly, if S208 is performed, S209 may be performed if the AS layer of the UE determines that the measured value of the third network is greater than the third threshold, and S209 may not be performed if the AS layer of the UE determines that the measured value of the third network is less than or equal to the third threshold, which also means that the AS layer of the UE selects a network according to the first indication information. That is, the AS layer of the UE performs screening by introducing the third threshold, so AS to report the network with better signal quality to the NAS layer of the UE for selection, and for the network with poorer signal quality, the AS layer of the UE may not report to the NAS layer of the UE, and the NAS layer of the UE may not select these networks.

If S211 is regarded that the NAS layer of the UE selects a network according to the first indication information, and there may be a plurality of different selection manners, which are described in different steps below.

S2111, the NAS layer of the UE selects a second network from the networks to be selected, and the networks to be selected comprise networks without the first indication information. For example, the network to be selected in S2111 is referred to as a first type network, and the first type network belongs to a second type network, which includes the network to be selected described above when describing the network selection procedure of the NAS layer of the UE under several circumstances. It can be considered that in this manner of S2111, the network with the first indication information is removed from the second type network, and selection is performed from the remaining networks (i.e., the first type network), for example, one network is selected from the remaining networks, and the selected network is referred to as the second network for convenience of description.

Taking the example of the UE being powered on or recovering from lack of coverage, and the "network" being "PLMN", the second type of network may include the RPLMN, PLMNs in the foregoing list, and PLMNs for which the AS layer has reported IDs. The NAS layer of the UE sequentially traverses these PLMNs when selecting, again in the order of priority as described above. For example, when traversing to a certain PLMN, the NAS layer of the UE may determine whether the PLMN carries the first indication information, and if the PLMN carries the first indication information, the NAS layer of the UE ignores the PLMN, continues to traverse a next PLMN, and continues to determine whether the next PLMN carries the first indication information; and if the PLMN does not carry the first indication information, the NAS layer of the UE determines whether the PLMN is optional (for example, if the NAS layer of the UE receives the ID of the PLMN from the AS layer of the UE, the NAS layer of the UE determines that the PLMN is optional), if the PLMN is optional, the NAS layer of the UE selects the PLMN, does not traverse other PLMNs, and if the PLMN is not optional, the UE continues to traverse the next PLMN and continues to determine whether the next PLMN carries the first indication information. And so on until the NAS layer of the UE selects to the second network, or until the UE selection fails. That is, the first type network is removed from the second type network, and the first type network is not removed uniformly, but the UE ignores the network with the first indication information in the process of traversing the network, and thus the first type network is considered to be removed.

Optionally, if the UE fails to select, the UE may traverse the second type of network without the first type of network again according to the priority order, so as to reduce the probability that the UE has no network selection due to coverage problem.

The network with the first indication is the network where the UE has experienced an RLF event, and there may be a risk of poor signaling if the UE selects such a network. Therefore, in this way, when the NAS layer of the UE selects, the network with the first indication information may be ignored, that is, the UE may not select the network with the first indication information. In addition, by the method, the number of the networks which need to be determined whether to be selectable when the UE selects the network can be reduced, and the efficiency of selecting the network by the UE can be improved.

S2112, the NAS layer of the UE selects a second network from the networks to be selected according to the first threshold and the first indication information. The network to be selected in S2111 is a first-type network, and the network to be selected in S2112 is a second-type network described in S2111. The second type of network includes the network to be selected as described above when describing the network selection process of the NAS layer of the UE under several conditions, that is, in S2112, the network is not removed from the second type of network, and the second type of network is used as the network to be selected. It can be considered that in the manner of S2112, selection is made in the second type of network, for example, one network is selected in the second type of network, and the selected network is referred to as the second network for convenience of description.

S2112 can be implemented in several different ways, as exemplified below.

1. In a first embodiment, the NAS layer of the UE determines whether the network to be selected is optional according to a first method.

That is, for any one of the networks to be selected, the NAS layer of the UE determines whether the network is optional according to the first manner. The first manner is associated with a first threshold, for example the first manner comprises: if the measured value of one network is greater than the first threshold, the network is selected, otherwise the network is not selected. The first threshold is specified by a protocol, or configured by a network device, or may be determined by the UE itself, or configured in a SIM card or a USIM card, for example.

The NAS layer of the UE may select a network if the measurement of the network is greater than the first threshold. Of course, the premise is that the NAS layer of the UE receives the identity of the network from the AS layer of the UE, and if the NAS layer of the UE does not receive the identity of the network from the AS layer of the UE, even if the measurement value of the network is greater than the first threshold, it is not optional. From this point of view, the first mode may also be considered to include: if the measured value of one network is greater than the first threshold and the NAS layer of the UE receives the identification of the network from the AS layer of the UE, the network is optional, otherwise the network is not optional.

Taking the UE powered on or recovering from lack of coverage AS an example, and taking "network" is "PLMN" AS an example, the network to be selected is the second type of network, which may include RPLMN, PLMNs in the foregoing list, and PLMNs whose IDs are reported by the AS layer. The NAS layer of the UE sequentially traverses these PLMNs when selecting, again in the order of priority as described above. For example, the NAS layer of the UE may determine whether the measured value of a PLMN is greater than a first threshold and whether an ID of the PLMN is received from the AS layer of the UE when traversing to the PLMN. If the measured value of the PLMN is greater than the first threshold and the NAS layer of the UE has received the ID of the PLMN from the AS layer of the UE, the UE can select the PLMN without traversing other PLMNs; and if the measured value of the PLMN is less than or equal to the first threshold and/or the NAS layer of the UE does not receive the ID of the PLMN from the AS layer of the UE, the PLMN is not selectable, the NAS layer of the UE continues to traverse the next PLMN and continues to determine whether the measured value of the next PLMN is greater than the first threshold and determines whether the ID of the next PLMN is received from the AS layer of the UE. And so on until the network is selected or the network to be selected is traversed completely.

If the network is not selected after the traversal of the network to be selected is completed, the UE can traverse the network to be selected again, and in the traversal process, the first threshold is not additionally added to the network. For example, the NAS layer of the UE may determine whether an ID of a certain PLMN is received from the AS layer of the UE when traversing to the PLMN. If the NAS layer of the UE has received the ID of the PLMN from the AS layer of the UE, the UE may select the PLMN without traversing other PLMNs; and if the NAS layer of the UE does not receive the ID of the PLMN from the AS layer of the UE, the PLMN is not selected, the NAS layer of the UE continues to traverse the next PLMN and continues to determine whether the ID of the next PLMN is received from the AS layer of the UE. And so on until the selection to the network or until the selection fails.

It is understood for the first embodiment that, for all networks to be selected, a first threshold is additionally introduced to determine whether the network can be selected. This selection is more rigid and more conducive to selecting a network with better signal quality.

2. In the first embodiment, the NAS layer of the UE determines whether a network having the first indication information in the network to be selected is selectable according to the first manner, and determines whether a network not having the first indication information in the network to be selected is selectable according to the second manner. In other words, the second embodiment includes: for the networks with the first indication information in the networks to be selected, determining whether the networks are selectable by the NAS layer of the UE according to a first mode; and for the networks without the first indication information in the networks to be selected, the NAS layer of the UE determines whether the networks are selectable according to a second mode.

That is, for the network with the first indication information in the network to be selected, the NAS layer of the UE determines whether the network is selectable according to the first manner, and for the network without the first indication information in the network to be selected, the NAS layer of the UE determines whether the network is selectable according to the second manner. Reference is made to the preceding for a description of the first mode. The second manner is independent of the first threshold, for example the second manner comprises: the NAS layer of the UE receives the identification of one network from the AS layer of the UE, and the network is optional, otherwise, the network is not optional.

Taking the UE being powered on or recovering from lack of coverage AS an example, and taking "network" being "PLMN" AS an example, the network to be selected is a second type of network, which may include RPLMN, PLMNs in the foregoing list, and PLMNs whose IDs are reported by the AS layer. The NAS layer of the UE sequentially traverses these PLMNs when selecting, again in the order of priority as described above. For example, the NAS layer of the UE may determine whether a PLMN carries the first indication information when traversing to the PLMN, determine whether a measurement value of the PLMN is greater than a first threshold if the PLMN carries the first indication information, and determine whether an ID of the PLMN is received from the AS layer of the UE. If the measured value of the PLMN is greater than the first threshold and the NAS layer of the UE has received the ID of the PLMN from the AS layer of the UE, the UE can select the PLMN without traversing other PLMNs; and if the measured value of the PLMN is less than or equal to the first threshold and/or the NAS layer of the UE does not receive the ID of the PLMN from the AS layer of the UE, the PLMN is not selected, the NAS layer of the UE continues to traverse the next PLMN and continues to determine whether the next PLMN carries the first indication information. Or, if the NAS layer of the UE determines that the PLMN does not carry the first indication information, the NAS layer of the UE determines whether the ID of the PLMN is received from the AS layer of the UE. If the NAS layer of the UE has received the ID of the PLMN from the AS layer of the UE, the UE may select the PLMN without traversing other PLMNs; and if the NAS layer of the UE does not receive the ID of the PLMN from the AS layer of the UE, the PLMN is not selected, the NAS layer of the UE continues to traverse the next PLMN, and whether the next PLMN carries the first indication information is continuously determined. And so on until the network is selected or the network to be selected is traversed completely.

If the network is not selected after the traversal of the network to be selected is completed, the UE may traverse the network to be selected again, and in the traversal process, the first threshold is not additionally added to the network with the first indication information. For example, the NAS layer of the UE may determine whether an ID of a certain PLMN is received from the AS layer of the UE when traversing to the PLMN. If the NAS layer of the UE has received the ID of the PLMN from the AS layer of the UE, the UE can select the PLMN without traversing other PLMNs; and if the NAS layer of the UE does not receive the ID of the PLMN from the AS layer of the UE, the PLMN is not selected, the NAS layer of the UE continues to traverse the next PLMN and continues to determine whether the ID of the next PLMN is received from the AS layer of the UE. And so on until selection to the network or until selection fails.

It can be understood for the second embodiment that for the network with the first indication information, the first threshold may be additionally introduced to reduce the probability that the UE selects the network with the poor signal quality. For networks without the first indication information, the RLF event may not occur in these networks by the UE, so that the signal quality of the UE in these networks may not be too poor, and therefore, the first threshold may not need to be additionally introduced into these networks, thereby reducing the determination process of the UE and improving the efficiency of network selection.

S2111 and S2112 are two different implementations (of course, two different implementations are included in S2112). For example, if the NAS layer of the UE determines that the first network does not correspond to the first indication information, S2111 may be performed, and if the NAS layer of the UE determines that the first network corresponds to the first indication information, any of the embodiments of S2112 may be performed. Alternatively, S2111 may be performed without performing S2112 regardless of whether the first network corresponds to the first indication information. Alternatively, S2112 may be performed without performing S2111 regardless of whether the first network corresponds to the first indication information.

The first network is, for example, any one of the second type of networks, or the first network is, for example, any one of the networks in which the NAS layer of the UE receives the identification from the AS layer of the UE, or the first network is, for example, the network in which the UE has registered last time (e.g., the RPLMN of the UE last time). According to the existing network selection method, the UE has a high probability of selecting the RPLMN of the last time, and if the signal quality of the RPLMN is poor, the RPLMN may fall into a coverage hole. Therefore, in the embodiment of the present application, the first network is, for example, the RPLMN of the UE last time, and if the RPLMN has the first indication information, the UE may select a network by using any one of the embodiments S2111 or S2112, and through these embodiments, the selection manner from the inertial selection of the UE to the RPLMN of the last time is broken, and the UE may select a network with better signal quality as much as possible.

Alternatively, if a screening mechanism of the AS layer is introduced, the NAS layer of the UE may not select in the manner of S2111 or S2112, but may select a network in the existing normal manner, which may refer to the related contents described before the embodiment shown in fig. 2 is described. That is, if the screening mechanism of the AS layer is introduced, the NAS layer of the UE may select a network in a normal manner, and the NAS layer of the UE may follow the existing mechanism, so AS to be better compatible with the existing manner. When the network selection is performed according to the existing normal mode, because the measured value is less than or equal to the second threshold and the AS layer of the UE does not send the identifiers of the networks to the NAS layer of the UE for the networks in which the RLF event occurs, the NAS layer of the UE does not select the networks when selecting the networks, thereby improving the quality of the networks selected by the UE and reducing the situation that the UE falls into or continuously falls into a coverage hole. Or even if a screening mechanism of the AS layer is introduced, the NAS layer of the UE may continue to select a network in the manner of S2111 or S2112, which is not limited in the embodiment of the present application.

In the embodiment of the present application, S201 to S209 are optional steps, and S2111 to S2111 are also optional steps.

In this embodiment, the NAS layer of the UE (or the AS layer of the UE) may additionally add a selection criterion to part of or all of the networks to be selected, for example, additionally introduce a first threshold (or a third threshold), respectively determine whether a measured value of a corresponding network is greater than the first threshold (or the third threshold) for part of or all of the networks to be selected, if the measured value of a certain network is greater than the first threshold (or the third threshold), the network may be selected, and if the measured value of a certain network is less than or equal to the first threshold (or the third threshold), the network is not selected. Equivalently, since the RLF event occurs in the network that the UE has registered last time, which indicates that the signal of the network that the UE has registered last time is not good, the UE may introduce the first threshold (or the third threshold) to select the network, and select the network with better signal as much as possible through the first threshold (or the third threshold). Alternatively, the NAS layer of the UE may be disregarded for the network with the first indication information. Therefore, the probability that the UE always resides in the network with poor signals can be reduced, the communication quality of the UE is improved, and the operation and maintenance cost of the UE is reduced. Also in this way, the probability of a UE falling or continuing to fall into a coverage hole can be reduced.

With the embodiment shown in fig. 2, the probability that a UE falls or continues to fall into a coverage hole can be reduced. In addition, the embodiment of the present application provides a second communication method, in which the probability that more UEs fall into or continuously fall into a coverage hole may be reduced through the intervention of a network device. Please refer to fig. 3, which is a flowchart of the method.

S301, after selecting the second network, the UE sends second indication information to the network equipment, and correspondingly, the network equipment receives the second indication information from the UE. For example, the UE selects the second network through the selection method provided by the embodiment shown in fig. 2, or the UE may select the second network by using the existing selection method instead of the selection method provided by the embodiment shown in fig. 2.

For example, the UE is an IoT UE, the network device is an IoT device manager maintained by an operator, and the UE may send the second indication information to the network device through the user plane. The IoT device manager is commonly maintained by multiple operators, for example, and is used for managing IoT devices covered by the multiple operators; alternatively, the IoT device manager is maintained by an operator to which the second network belongs, for example, and is used for managing the IoT devices covered by the operator.

The second indication information may indicate that the UE has experienced an RLF event at a second cell of the fourth network. That is, after the UE successfully selects a network, information about the network and the corresponding cell where the RLF event occurred in the UE may be sent to the network device, and the information may be used for network optimization. For example, the second indication information may include an identity of the fourth network and an identity of the second cell, where the UE may have experienced an RLF event in one or more cells of the fourth network, and the second cell may include the one or more cells. Optionally, the second indication information may further include information for indicating that the RLF event occurs in the UE, for example, the second indication information includes an identifier of a fourth network, an identifier of a second cell, and information for indicating that the RLF event occurs in the UE, so that the network device may determine that the RLF event has occurred in the second cell of the fourth network according to the second indication information. Alternatively, the second indication information may not include information indicating that the UE has an RLF event, and the network device may determine that the UE is in the cell of the network and the RLF event occurs as long as the UE sends the network identifier and the cell identifier to the network device. For example, the second indication information includes an identifier of the fourth network and an identifier of the second cell, the network device may determine that the RLF event has occurred in the second cell of the fourth network according to the second indication information. Or, the second indication information may also include a network identifier, a cell identifier, and location information of the RLF event occurring in the UE, where the location information is, for example, location information, and then the network device may determine, according to the location information, a coverage hole location of the cell where the RLF event occurs more accurately.

Optionally, the second indication information may include, in addition to the related information indicating the network where the UE fails, a network identifier and a cell identifier that are currently selectable by the UE, or include a network identifier and a cell identifier that have been successfully selected by the UE. The network device may determine which networks are available and which networks may have problems in the current location according to the second indication information, so as to guide the network selection of the UE subsequently.

S302, the network equipment executes a first processing mode. By executing the first processing mode, the difficulty of selecting the second cell by the UE can be improved.

The first processing method includes, for example, method 1 and/or method 2, and may include other methods in addition thereto. Mode 1 and mode 2 are described below.

Mode 1, a cell selection criterion is reconfigured for the second cell to improve the difficulty of the UE in selecting the second cell.

For example, the network device may negotiate with an operator corresponding to the fourth network (for example, may negotiate with a core network device provided by the operator through a message interaction manner), so as to change the cell selection criterion of the second cell, for example, the camping threshold of the second cell may be increased. If the camping threshold is increased, the value of the first parameter that needs to be measured is higher if the UE camps on the second cell, which is also equivalent to increasing the difficulty of selecting the second cell by the UE, that is, reducing the number of UEs that can select the second cell. And the second cell is a cell in which some UEs have RLF, which indicates that the signal quality of the second cell is not good, so that fewer UEs select the second cell by increasing the difficulty of selecting the second cell, and the UEs can reside in the cell with good signal quality as much as possible, thereby reducing the probability that more UEs fall into or continuously fall into the coverage hole, and improving the communication quality of the UEs.

Mode 2, configuring a first threshold for at least one UE, where the first threshold is used for the UE to determine whether a second cell can be selected. The difficulty of selecting the second cell by the UE can be improved through the first threshold. For example, the network device is an IoT device manager, and the at least one UE includes, for example, some or all of the IoT UEs managed by the IoT device manager.

With regard to the manner of using the first threshold, reference may be made to the description of the embodiment shown in fig. 2. Configuring the first threshold for the UE is equivalent to additionally adding a condition for selecting the second cell to the UE, which is equivalent to improving the difficulty of selecting the second cell by the UE. By improving the difficulty of selecting the second cell by the UE, less UEs can be selected to the second cell, so that the UEs can reside in the cell with better signal quality as much as possible, the probability that more UEs fall into or continuously fall into a coverage hole is reduced, and the communication quality of the UEs is improved.

Whether the network device employs mode 1, or mode 1 and mode 2 may be determined by the network device, for example, the network device may be determined based on actual circumstances. For example, if a plurality of UEs indicate to the network device that an RLF event has occurred in the second cell of the fourth network, for example, the number of UEs indicating to the network device that an RLF event has occurred in the second cell of the fourth network is greater than the first number, the network device may adopt the method 1, or adopt the methods 1 and 2. Since the number of UEs having RLF events occurring in the second cell of the fourth network is large, the probability of the second cell having problems is large, and it is reasonable to adopt the method 1 in this case. Of course, in this case, the method 1 and the method 2 may also be adopted, and the configuration efficiency may be improved by configuring the cell and the UE together, so that more UEs can better achieve the goal of selecting a network with better signal quality. The first number is specified, for example, by a protocol or is determined by the network device itself. For example, the network device may know the total number of UEs served by the second cell, and the first number is, for example, greater than or equal to half of the total number of UEs served by the second cell.

For another example, if only a small number of UEs indicate to the network device that an RLF event occurred at the second cell of the fourth network, e.g., the number of UEs indicating to the network device that an RLF event occurred at the second cell of the fourth network is less than the second number, then the network device may employ manner 2. Since the smaller number of UEs having RLF events in the second cell of the fourth network may be a problem for these UEs themselves, while the second cell may not have a problem, for example, the UEs may be located at the edge of the second cell and result in poor signal quality, it is reasonable to adopt approach 2 in this case.

Alternatively, whether the network device adopts the mode 1, or the mode 1 and the mode 2 may also be defined by a protocol, and the embodiment of the present application is not limited.

In the embodiment of the application, the UE can obtain more information through interaction between the UE and the network device, or the UE can provide more information for the network for subsequent configuration of a cell, so that the UE can be helped to select a more appropriate network. With network participation, the probability that more UEs fall or continue to fall into a coverage hole can be reduced.

Next, consider a problem. If a UE roams into an unfamiliar area, the UE needs to re-search for a cell to re-register with the local network. Since the UE has not arrived in the area before, the UE needs to perform blind search on the strange frequency band. For example, when a user moves from europe to china, the home PLMN of the user's handset is the PLMN provided by the european operator, and the handset is currently in a roaming state, the handset needs to search for a cell of the chinese operator for access. Since the mobile phone has not arrived in china before, the UE does not store information of the local PLMN in china, and therefore the mobile phone needs to search blindly. In addition, after the UE searches for and registers with a PLMN, the UE may also need to perform periodic network selection, or the UE may be powered on again or recover from lack of coverage, that is, the UE may also need to face multiple search procedures. And in each searching process, the UE needs to search blindly in the unfamiliar frequency band. The blind search in the strange frequency band needs to consume more time, and is not beneficial to the energy conservation of the UE.

In view of this, the embodiment of the present application provides a third communication method, by which the time for blind search of the UE can be reduced, and the power of the UE can be saved. Please refer to fig. 4, which is a flowchart of the method. The process of searching for a network by the UE described in the method may be performed by, for example, the AS layer of the UE, or may be performed by other protocol layers of the UE.

S401, after selecting the second network, the UE sends the identifier of the second network and the identifier of the third cell to the network equipment, and correspondingly, the network equipment receives the identifier of the second network and the identifier of the third cell from the UE. Or after selecting the second network, the UE sends the request information to the network device, and accordingly, the network device receives the request information from the UE. The request information can be used to request information of the surrounding available cells. The third cell is, for example, a cell in which the UE currently camps. For example, the UE selects the second network through the selection method provided by the embodiment shown in fig. 2, or the UE may select the second network by using the existing selection method instead of the selection method provided by the embodiment shown in fig. 2.

For example, the UE is an IoT UE, the network device is an IoT device manager maintained by an operator, and the UE may send the identity of the second network and the identity of the third cell to the network device through the user plane. The IoT device manager is commonly maintained by multiple operators, for example, and is used for managing IoT devices covered by the multiple operators; alternatively, the IoT device manager is maintained by an operator to which the second network belongs, for example, and is used for managing the IoT devices covered by the operator. For example, the UE may send information directly to the network device (e.g., send the identifier of the second network and the identifier of the third cell, or send request information), or the UE may send information to the network device through an access network device or a core network device serving the UE (e.g., send the identifier of the second network and the identifier of the third cell, or send request information).

The UE, for example, roams to an unfamiliar area, and the UE performs a blind search in the unfamiliar area. For example, if the UE selects the second network by blind search, the UE registers with the second network and camps on a third cell under the second network. In this case, the UE may send the identifier of the second network and the identifier of the third cell to the network device through the second network, or the UE may send request information to an access network device or a core network device serving the UE through the second network, the access network device or the core network device determines the identifier of the second network and the identifier of the third cell where the UE is currently located, and then sends the identifier of the second network and the identifier of the third cell to the network device, or the UE may send request information to the network device through the second network, and the network device determines the identifier of the second network and the identifier of the third cell where the UE is currently located.

S402, the network equipment sends information of M networks to the UE, and correspondingly, the UE receives the information of M networks from the network equipment. The M networks are, for example, networks in an area where the third cell is located, and M is a positive integer.

After receiving the identifier of the second network and the identifier of the third cell, the network device may determine information of one or more networks in the area where the third cell is located, for example, may determine frequency (frequency band or frequency point) information of the one or more networks in the area where the third cell is located, and may send the determined information of the networks to the UE. Alternatively, after receiving the request information, the network device may determine a third cell in which the UE is located (or determine a third cell under a second network in which the UE is located), so as to determine information of one or more networks in an area in which the third cell is located, for example, frequency information of one or more networks in the area in which the third cell is located, and may send the determined information of the networks to the UE.

S403, when the network is selected again, the UE searches available networks according to the information of the M networks.

For example, the UE needs to search for a network again when the UE is powered off and then powered on, or the UE recovers from lack of coverage, or the UE periodically selects a network. Then the UE may search according to the information of the M networks when it needs to search for a network, for example, the information of the M networks includes frequencies of the M networks, and then the UE may search on some or all of the frequencies of the M networks, and the UE may not search for other frequencies except the frequencies of the M networks, or may reduce the number of searched frequencies. By the method, the search range of the UE can be narrowed, so that the search time of the UE is shortened, and the energy conservation of the UE is facilitated. And the networks are determined by the network equipment, and the probability that the UE can search the cell is higher, so the search success rate of the UE can be improved.

The embodiment shown in fig. 2, the embodiment shown in fig. 3 and the embodiment shown in fig. 4 can be applied in combination. For example, the UE may search for a network through the embodiment shown in fig. 4, select a network through the embodiment shown in fig. 2, and send second indication information to the network device through the embodiment shown in fig. 3 after selecting a network. Alternatively, any two of the embodiments shown in fig. 2, 3, and 4 may be applied in combination. For example, the embodiment shown in fig. 2 is applied in combination with the embodiment shown in fig. 3, for example, the UE may select a network through the embodiment shown in fig. 2, and may further send second indication information to the network device through the embodiment shown in fig. 3 after selecting the network. For another example, the embodiment shown in fig. 2 is applied in combination with the embodiment shown in fig. 4, for example, the UE may search for a network through the embodiment shown in fig. 4 and select a network through the embodiment shown in fig. 2. For another example, the embodiment shown in fig. 3 is applied in combination with the embodiment shown in fig. 4, for example, the UE may search for a network through the embodiment shown in fig. 4, and may further send second indication information to the network device through the embodiment shown in fig. 3 after selecting the network. Alternatively, the embodiment shown in fig. 2, the embodiment shown in fig. 3, and the embodiment shown in fig. 4 may not be combined, but may be applied independently.

In summary, in the embodiment of the present application, when the UE selects a network, the UE may select according to the first indication information, for example, the UE may increase the selection threshold, or the UE may ignore the network with the first indication information when selecting, so as to select a network with better signal quality as much as possible, reduce the probability that the UE always resides in a network with a worse signal, and improve the communication quality of the UE. And through the intervention of network equipment, the search time of the UE can be reduced, and the energy conservation of the UE is facilitated.

Fig. 5 is a schematic structural diagram of a communication apparatus 500 according to an embodiment of the present disclosure. The communication apparatus 500 may be the terminal device described in any one of the embodiments shown in fig. 2 to fig. 4, and is configured to implement the method performed by the terminal device in the foregoing method embodiment. Alternatively, the communication apparatus 500 may also be the network device described in any one of the embodiments shown in fig. 2 to fig. 4, and is configured to implement the method corresponding to the network device in the foregoing method embodiments. The specific functions can be seen from the description of the above method embodiments.

The communication device 500 includes one or more processors 501. The processor 501 may also be referred to as a processing unit and may perform certain control functions. The processor 501 may be a general purpose processor or a special purpose processor, etc. For example, it includes: a baseband processor, a central processing unit, an application processor, a modem processor, a graphics processor, an image signal processor, a digital signal processor, a video codec processor, a controller, a memory, and/or a neural network processor, among others. The baseband processor may be used to process communication protocols as well as communication data. The central processor may be used to control the communication device 500, execute software programs and/or process data. The different processors may be separate devices or may be integrated in one or more processors, e.g. on one or more application specific integrated circuits.

Optionally, one or more memories 502 are included in the communication device 500 to store instructions 504, and the instructions 504 can be executed on the processor to enable the communication device 500 to perform the method described in the above method embodiments. Optionally, the memory 502 may further store data. The processor and the memory may be provided separately or may be integrated together.

Optionally, the communication device 500 may include instructions 503 (which may also be sometimes referred to as code or program), and the instructions 503 may be executed on the processor, so that the communication device 500 performs the method described in the above embodiments. Data may be stored in processor 501.

Optionally, the communication device 500 may further include a transceiver 505 and an antenna 506. The transceiver 505 may be referred to as a transceiver unit, a transceiver circuit, a transceiver, an input/output interface, etc. for implementing the transceiving function of the communication device 500 through the antenna 506.

Optionally, the communication device 500 may further include one or more of the following components: the wireless communication module, the audio module, the external memory interface, the internal memory, the Universal Serial Bus (USB) interface, the power management module, the antenna, the speaker, the microphone, the input/output module, the sensor module, the motor, the camera, or the display screen, etc. It is understood that in some embodiments, the communications apparatus 500 may include more or fewer components, or some components integrated, or some components separated. These components may be hardware, software, or a combination of software and hardware implementations.

The processor 501 and the transceiver 505 described in the embodiments of the present application may be implemented on an Integrated Circuit (IC), an analog IC, a radio frequency integrated circuit (RFID), a mixed signal IC, an Application Specific Integrated Circuit (ASIC), a Printed Circuit Board (PCB), an electronic device, or the like. The communication apparatus implementing the present description may be a standalone device (e.g., a standalone integrated circuit, a mobile phone, etc.), or may be a part of a larger device (e.g., a module that can be embedded in other devices), and may refer to the foregoing description about the terminal device and the network device, which is not described herein again.

The embodiment of the present application provides a terminal device, which (for convenience of description, referred to as UE) may be used in the foregoing embodiments. The terminal device comprises corresponding means (means), units and/or circuits to implement the terminal device functionality as described in any of the embodiments shown in fig. 2 to 4. For example, the terminal device includes a transceiver module for supporting the terminal device to implement a transceiver function, and a processing module for supporting the terminal device to process a signal.

Fig. 6 is a schematic structural diagram of a terminal device according to an embodiment of the present application.

The terminal device 600 may be adapted to the architecture shown in fig. 1. For convenience of explanation, fig. 6 shows only the main components of the terminal apparatus 600. As shown in fig. 6, the terminal apparatus 600 includes a processor, a memory, a control circuit, an antenna, and an input-output device. The processor is mainly used for processing a communication protocol and communication data, controlling the entire terminal device 600, executing a software program, and processing data of the software program. The memory is used primarily for storing software programs and data. The control circuit is mainly used for converting baseband signals and radio frequency signals and processing the radio frequency signals. The antenna is mainly used for receiving and transmitting radio frequency signals in the form of electromagnetic waves. Input and output devices, such as touch screens, display screens, microphones, keyboards, etc., are mainly used for receiving data input by users and outputting data to users.

Taking the terminal device 600 as a mobile phone as an example, when the terminal device 600 is powered on, the processor may read the software program in the storage unit, interpret and execute the instruction of the software program, and process the data of the software program. When data needs to be sent wirelessly, the processor performs baseband processing on the data to be sent and outputs baseband signals to the control circuit, and the control circuit performs radio frequency processing on the baseband signals and sends the radio frequency signals to the outside in the form of electromagnetic waves through the antenna. When data is transmitted to the terminal device 600, the control circuit receives a radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, and the processor converts the baseband signal into data and processes the data.

Those skilled in the art will appreciate that fig. 6 shows only one memory and processor for ease of illustration. In some embodiments, terminal device 600 may include multiple processors and memories. The memory may also be referred to as a storage medium or a storage device, and the like, which is not limited in this respect in the embodiment of the present invention.

As an alternative implementation manner, the processor may include a baseband processor and a central processing unit, the baseband processor is mainly used for processing the communication protocol and the communication data, and the central processing unit is mainly used for controlling the whole terminal device 600, executing the software program, and processing the data of the software program. The processor in fig. 6 integrates the functions of the baseband processor and the central processing unit, and those skilled in the art will understand that the baseband processor and the central processing unit may also be independent processors, and are interconnected through a bus or the like. The terminal device 600 may include a plurality of baseband processors to accommodate different network systems, the terminal device 600 may include a plurality of central processors to enhance its processing capability, and various components of the terminal device 600 may be connected by various buses. The baseband processor can also be expressed as a baseband processing circuit or a baseband processing chip. The central processing unit can also be expressed as a central processing circuit or a central processing chip. The function of processing the communication protocol and the communication data may be built in the processor, or may be stored in the storage unit in the form of a software program, and the processor executes the software program to realize the baseband processing function.

In one example, the antenna and the control circuit having the transceiving function can be regarded as the transceiving unit 610 of the terminal device 600, and the processor having the processing function can be regarded as the processing unit 620 of the terminal device 600. As shown in fig. 6, the terminal device 600 includes a transceiving unit 610 and a processing unit 620. A transceiver unit may also be referred to as a transceiver, a transceiving device, etc. Optionally, a device for implementing a receiving function in the transceiver unit 610 may be regarded as a receiving unit, and a device for implementing a transmitting function in the transceiver unit 610 may be regarded as a transmitting unit, that is, the transceiver unit 610 includes a receiving unit and a transmitting unit. For example, the receiving unit may also be referred to as a receiver, a receiving circuit, etc., and the sending unit may be referred to as a transmitter, a transmitting circuit, etc.

The embodiment of the present application further provides a network device, which can be used in the foregoing embodiments. The network device comprises means (means), units and/or circuits to implement the functionality of e.g. the network device as described in any of the embodiments shown in fig. 2 to 4. For example, the network device includes a transceiver module for supporting the network device to implement a transceiver function, and a processing module for supporting the network device to process signals.

Fig. 7 is a schematic structural diagram of a network device according to an embodiment of the present application. As shown in fig. 7, the network device may be adapted to the architecture shown in fig. 1. The network device includes: a baseband device 701, a radio frequency device 702, and an antenna 703. In the uplink direction, the radio frequency apparatus 702 receives information sent by the terminal device through the antenna 703, and sends the information sent by the terminal device to the baseband apparatus 701 for processing. In the downlink direction, the baseband device 701 processes the information of the terminal device and sends the information to the radio frequency device 702, and the radio frequency device 702 processes the information of the terminal device and sends the information to the terminal device through the antenna 703.

The baseband device 701 includes one or more processing units 7011, a memory unit 7012, and an interface 7013. Wherein the processing unit 7011 is configured to support the network device to perform the functions of the network device in the foregoing method embodiments. The storage unit 7012 is used to store software programs and/or data. The interface 7013 is used for exchanging information with the radio frequency device 702 and includes interface circuitry for input and output of information. In one implementation, the processing unit is an integrated circuit, such as one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits may be integrated together to form a chip. The memory unit 7012 and the processing unit 7011 may be located in the same chip, i.e., on-chip memory elements. Alternatively, memory unit 7012 may be on a different chip than processing unit 7011, i.e., an off-chip memory element. The storage unit 7012 may be a single memory or a combination of multiple memories or storage elements.

A network device may implement some or all of the steps in the above-described method embodiments in the form of one or more processing unit schedulers. For example, to implement the corresponding functionality of the network device described in any of the embodiments shown in fig. 2 to 4. The one or more processing units may support wireless access technologies of the same system, and may also support wireless access systems of different systems.

Those of ordinary skill in the art will appreciate that the various illustrative elements and steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, for example, the division of the units is only one logical functional division, the units illustrated as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. The computer readable storage medium can be any available medium that can be accessed by a computer. Take this as an example but not limiting: a computer-readable medium may include a Random Access Memory (RAM), a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), a compact disc read-only memory (CD-ROM), a universal serial bus flash disk (universal serial bus flash disk), a removable hard disk, or other optical disk storage, magnetic disk storage media, or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. In addition, by way of illustration and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), or direct rambus RAM (DR RAM).

The above description is only for the specific implementation of the present application, but the scope of the embodiments 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 embodiments of the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of communication, comprising:

in the process of selecting a network, terminal equipment obtains first indication information, wherein the first indication information is used for indicating that the terminal equipment generates a radio link failure event in the network corresponding to the first indication information;

and the terminal equipment selects a network according to the first indication information.

2. The method of claim 1, further comprising:

and the NAS layer of the terminal equipment determines that the first indication information corresponds to a first network, and the first network is a network which is registered by the terminal equipment for the last time.

3. The method according to claim 1 or 2, wherein the terminal device selects a network according to the first indication information, comprising:

and the NAS layer of the terminal equipment selects a second network from the networks to be selected according to the first threshold and the first indication information.

4. The method of claim 3, wherein selecting, by the NAS layer of the terminal device, the second network from the networks to be selected according to the first threshold and the first indication information comprises:

the NAS layer of the terminal equipment selects the second network from the networks to be selected; wherein the content of the first and second substances,

the NAS layer of the terminal equipment determines whether a network with the first indication information in the network to be selected is optional according to a first mode, and determines whether a network without the first indication information in the network to be selected is optional according to a second mode; or, the NAS layer of the terminal device determines whether all the networks in the to-be-selected networks are selectable according to a first mode; the first mode is related to the first threshold, the second mode is unrelated to the first threshold, and the first threshold is used for the terminal equipment to select a network under the condition that the first indication information exists.

5. The method of claim 1, wherein the terminal device selects a network according to the first indication information, and wherein the selecting comprises:

and the NAS layer of the terminal equipment selects a second network from the networks to be selected, wherein the networks to be selected comprise the networks without the first indication information.

6. The method according to any one of claims 1 to 5, wherein the obtaining of the first indication information by the terminal device comprises:

under the condition that the measured value of a first cell corresponding to a third network is less than or equal to a second threshold, determining whether a radio link failure event occurs in the third network by the terminal equipment through an AS layer of the terminal equipment, wherein the terminal equipment meets the cell selection standard of the first cell;

if the terminal device has a radio link failure event in the third network, the AS layer of the terminal device sends, to the NAS layer of the terminal device, a measurement value of the first cell corresponding to the third network and an identifier of at least one network, and sends at least one piece of the first indication information corresponding to the at least one network, where the at least one network includes all networks or part of networks corresponding to the first cell, and the at least one network includes the third network.

7. The method of claim 6, further comprising:

and under the condition that the measured value of the first cell corresponding to the third network is greater than a second threshold, the AS layer of the terminal device sends the identifier of the third network to the NAS layer of the terminal device, and indicates that the third network is a high-quality network.

8. The method of claim 1, wherein the obtaining of the first indication information by the terminal device comprises:

in the case that a measurement value of a first cell corresponding to a third network is less than or equal to a second threshold, determining, by the AS layer of the terminal device, whether a radio link failure event has occurred at the third network by the terminal device, wherein the terminal device satisfies a cell selection criterion of the first cell;

if the terminal equipment has a radio link failure event in the third network, the AS layer of the terminal equipment obtains the first indication information of the third network.

9. The method of claim 8, wherein the terminal device selects a network according to the first indication information, and wherein the selecting the network comprises:

and the AS layer of the terminal equipment does not send the identifier of the third network to the NAS layer of the terminal equipment, wherein the identifier of the third network is not sent for the NAS layer of the terminal equipment not to select the third network when selecting the network.

10. The method according to any one of claims 1 to 9, further comprising:

and after selecting the second network, sending second indication information to the network equipment, wherein the second indication information is used for indicating that the terminal equipment has a radio link failure event in a second cell of a fourth network.

11. The method according to any one of claims 1 to 10, further comprising:

after selecting a second network, sending an identifier of the second network and an identifier of a third cell in which the terminal device is located to network equipment;

receiving information of M networks from the network equipment, wherein the M networks are networks in an area where the third cell is located, and M is a positive integer;

and searching available networks according to the information of the M networks when the network is selected again.

12. The method according to any of claims 1 to 11, wherein the first network is a PLMN or an NPN.

13. A terminal device, comprising:

one or more processors;

one or more memories;

and one or more computer programs, wherein the one or more computer programs are stored in the one or more memories, the one or more computer programs comprising instructions which, when executed by one or more processors of the terminal device, cause the terminal device to perform the method of any of claims 1-12.

14. A computer-readable storage medium, for storing a computer program which, when run on a computer, causes the computer to perform the method of any one of claims 1 to 12.

15. A chip comprising one or more processors and a communication interface, the one or more processors configured to read instructions to perform the method of any one of claims 1 to 12.