Patent Description:
In 4th Generation (<NUM>) mobile communication technology, a Radio Resource Control (RRC) state of User Equipment (UE) includes a connect state and an idle state.

The connect state refers to a state in which there is an RRC connection established between the UE and a base station. The UE may perform data transceiving with the base station in the connect state. The idle state refers to a state in which there is no RRC connection established between the UE and the base station. The UE cannot transmit data to the base station in the idle state, but may receive a system message and paging message transmitted by the base station. Related technologies are known form the following documents:.

<CIT> discloses a device for efficient offloading and/or aggregation of resources by providing different levels of connection management in a network. It is object of the invention to provide a state keeping method and device, which can keep a UE in an inactive state. Inter Digital Communications "RAN Controlled State for New Radio Access", R2-<NUM>, discusses the transition of RRC from CONNECTED INACTIVE to INACTIVE, the transition condition is TRP/cell reselection to suitable cell in same RAN PA. <CIT> discloses a method implemented in a user equipment (UE) for use with a Radio Access Network (RAN). The method includes: the UE suspends an established RRC connection with the RAN; the UE monitories, whilst the RRC connection is suspended, for at least one of: paging and notifications of downlink data for the UE; and the UE stores RRC connection data related to the suspended RRC connection. <CIT> discloses a signaling optimization method, which includes: UE receives configuration information sent by a first network side device, where the configuration information includes a list, and the list is a cell list or a base station list; and the UE enters an intermediate state according to the configuration information, where the intermediate state means that: when the UE stores context information of the UE, if the UE moves and a cell movement range falls within a coverage area of a cell or a base station included in the list, the UE performs cell reselection according to the list. "<NPL>, discuss Draft Asynchronous Control Functions and Overall Control Plane Design. <NPL>, discusses for what cases this transition from INACTIVE to IDLE is supported (e.g. reject from network, other failure cases, other cases, etc.), and whether the RRC state transition from INACTIVE to CONNECTED can follow three step, two-step and one-step procedure. <NPL>, discusses state transitions from NR-INACTIVE to NR-IDLE. <NPL>, discusses for some cases, UE can just keep in INACTIVE state if the transmission can be finished during INACTIVE states.

It is object of the invention to provide a state keeping method and device, which can keep a UE in an inactive state.

The technical solutions provided by the embodiments of the present invention may achieve the following beneficial effects.

The inactive state is added in the UE, so that the UE in the inactive state may receive and transmit a small data packet service without being switched to the connect state. Therefore, the problem of signaling resource waste caused by the fact that the UE is required to be switched between the connect state and the idle state even in transceiving of the small data packet service in <NUM> is solved, and effects of enabling the UE in the inactive state to receive and transmit the small data packet service and saving signaling resources are achieved.

It should be understood that the above general descriptions and detailed descriptions below are only exemplary and explanatory and not intended to limit the present invention.

The examples associated with <FIG>, <FIG>, <FIG>, which are not covered by the claims, are not according to the invention and are present for illustration purposes only.

The terms "first", "second" and similar words mentioned in the present invention are adopted not to represent any sequence, number or importance but only to distinguish different parts. Similarly, similar words such as "one" or "a" also represent no number limits but existence of at least one. Similar words such as "connection" or "mutual connection" are not limited to physical or mechanical connection, but may include electrical connection, either direct or indirect.

The term "module" mentioned in the present invention usually refers to a process or instruction stored in a memory and capable of realizing some functions. The term "unit" mentioned in the present invention usually refers to a functional structure which is logically divided, and the "unit" may be implemented by pure hardware or implemented by a combination of software and hardware.

The term "multiple" or the wording "a plurality of' mentioned in the present invention refers to two or more than two. "And/or" describes an association relationship of associated objects, and represents that there may exist three relationships. A and/or B may represent the following three conditions: A independently exists, A and B simultaneously exist, and B independently exists. Character "/" usually represents that former and latter associated objects form an "or" relationship.

<FIG> is a structure diagram of a mobile communication system according to an embodiment of the present invention. In an example, the mobile communication system is a <NUM> system. The <NUM> system is also called a New Radio (NR) system. The mobile communication system may also be a <NUM>-system-based next-generation communication system. There are no limits made in the embodiment. The mobile communication system includes UE <NUM>, access network equipment <NUM> and a Mobility Management Entity (MME) terminal <NUM>.

The UE <NUM> refers to equipment performing data communication with the access network equipment <NUM>. The UE <NUM> may communicate with one or more core networks through a Radio Access Network (RAN). The UE <NUM> may also be called a subscriber unit, a subscriber station, a mobile station, a mobile, a remote station, an access point, a remote terminal, an access terminal, a user terminal, a user agent and a user device. In an example, the UE <NUM> may also be relay equipment, which will not be limited in the embodiment.

Relative to the UE <NUM>, the access network equipment <NUM> and the MME <NUM> belong to a network side. The network side includes the RAN and an Evolved Packet Core (EPC). The RAN is responsible for all radio related functions, including scheduling, radio resource management, a retransmission protocol, coding, various multi-antenna solutions and the like. The EPC is responsible for radio unrelated functions required to provide a complete mobile broadband network, including authentication, a charging function, establishment of a peer-to-peer connection and the like. The access network equipment <NUM> is network element equipment in the RAN, and the MME <NUM> is network element equipment in the EPC.

A wireless connection is established between the UE <NUM> and the access network equipment <NUM> through a wireless air interface. In an example, the wireless air interface is a SG-standard-based wireless air interface is an NR. Alternatively, the wireless air interface may also be a wireless air interface based on a next-generation mobile communication network technology of <NUM>. In an example, the wireless air interface is also compatible with a wireless air interface in an early-generation mobile communication network technology of 2nd Generation (<NUM>), 3rd Generation (<NUM>), 4th Generation (<NUM>) and the like.

The access network equipment <NUM> may be a base station. The base station may be a gNode-B (gNB) in a <NUM> system, configured to mutually convert a received radio frame and an Internet Protocol (IP) packet message, and may also coordinate attribute management over an air interface. In an example, the gNB is a base station adopting a central distributed architecture. When adopting the central distributed architecture, the access network equipment <NUM> usually includes a Central Unit (CU) and at least two Distributed Units (DUs). Protocol stacks of a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer and a Media Access Control (MAC) layer are set in the CU. Physical (PHY) protocol stacks are set in the DUs. A specific implementation manner for the access network equipment <NUM> will not be limited in the embodiment.

The access network equipment <NUM> is also connected with the MME <NUM> through a wireless network or a wired network (an optical communication network).

The MME <NUM> is responsible for bearer connection/release, state management and security key management of the UE.

<FIG> is a protocol architecture diagram of a mobile communication system according to an embodiment of the present invention. Equipment in the protocol architecture diagram includes UE <NUM>, access network equipment <NUM> and an MME <NUM>.

Protocol entities in the UE <NUM> are divided into two strata: a Non-Access Stratum (NAS) and an Access Stratum (AS).

The NAS of the UE <NUM> communicates with a NAS of the MME <NUM> to complete a functional operation between an EPC and a terminal.

The AS of the UE <NUM> includes a PDCP entity, an RLC protocol entity, a MAC protocol entity and a PHY protocol entity. The AS of the UE <NUM> communicates with an AS of the access network equipment <NUM> to complete a functional operation between the UE and a RAN. The AS is responsible for establishment of an RRC connection, transmission of an RRC message, establishment of a radio bearer, cancellation of the radio bearer, cutting-off of the RRC connection and the like.

The NAS and AS of the UE <NUM> may be switched between different states respectively.

With reference to <FIG>, a NAS state of the UE <NUM> includes two major states: an EMM-REGISTERED state and an EMM-DEREGISTERED state. EMM is an abbreviation of EPS mobility management. When the NAS of the UE <NUM> completes registration in the MME <NUM>, the NAS state is the EMM-REGISTERED state. When the NAS <NUM> of the UE <NUM> does not complete registration or cancels registration in the MME <NUM>, the NAS state is the EMM-DEREGISTERED state. In an example, the EMM-REGISTERED state may also be divided into a plurality of sub-states. The EMM-REGISTERED state is further divided into an EMM-connected state and an EMM-idle state.

With reference to <FIG>, an AS state of the UE <NUM> includes a connect state, an inactive state and an idle state, and the AS state is also called an RRC state. An AS state in a <NUM> system only includes the connect state and the idle state, so that the inactive state is a new state introduced into a <NUM> system.

The inactive state is an intermediate state between the connect state and the idle state. The inactive state includes, but not limited to, at least one of the following characteristics.

Herein, MM is management over location information, security and service continuity of a mobile terminal. Simply speaking, the UE <NUM> is kept mobile, MM is that the UE performs a location area update flow with a network side to enable the network side to learn about a current cell location of the UE when entering a new cell or tracking area.

When the UE <NUM> is in the connect state, MM is performed based on a cell handover mechanism. When the UE <NUM> is in the idle state, MM is performed based on cell reselection.

The network side includes the EPC and the RAN. A location area update flow between the UE <NUM> and the MME <NUM> may be called NAS location area update or EPC side location area update. A location area update flow between the UE <NUM> and the access network equipment <NUM> may be called RAN side location area update or AS location area update.

In the <NUM> system, the AS state of the UE <NUM> includes the connect state, the inactive state and the idle state.

In an example, when the UE <NUM> is switched from the connect state to the inactive state, the UE <NUM> is required to store the context.

In an example, when the UE <NUM> is switched from the inactive state to the connect state, if the UE <NUM> transmits an RRC connection recovery request to the access network equipment <NUM>, the UE <NUM> re-establishes an RRC connection with a residing cell provided by the access network equipment <NUM> in a recovery form by adopting the context stored in the inactive state, and is switched to the connect state after successfully re-establishing the RRC connection; and if the UE <NUM> transmits an RRC connection establishment request to the access network equipment <NUM>, the UE <NUM> deletes the context stored in the inactive state, and the UE <NUM> establishes the RRC connection with the residing cell provided by the access network equipment <NUM> in a creation form.

In an example, when the UE <NUM> is switched from the inactive state to the idle state, the UE <NUM> deletes the context stored in the inactive state, and then is switched to the idle state.

Herein, determining a specific triggering condition for triggering the UE <NUM> to switch among the three states is a technical problem to be solved by individual embodiments of the present invention.

<FIG> is a method flow chart showing a state switching method according to an embodiment. As shown in <FIG>, the state switching method is applied to UE <NUM> in a mobile communication system shown in <FIG>, and the method includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a predetermined condition or not. The predetermined condition is one of a first predetermined condition, a second predetermined condition and a third predetermined condition.

When an AS state (or called an RRC state) of the UE is in the inactive state, it is detected whether the UE meets the predetermined condition or not, the predetermined condition being the first predetermined condition, the second predetermined condition and the third predetermined condition.

In some embodiments, the "detection" action in Step <NUM> may be eliminated. After the first predetermined condition, the second predetermined condition or the third predetermined condition is triggered, Step <NUM> or Step <NUM> or Step <NUM> is directly executed, which will not be limited in the embodiment.

In Step <NUM>, when the UE meets the first predetermined condition, the UE is switched from the inactive state to an idle state.

That is, the AS state (or called the RRC state) of the UE is switched from the inactive state to the idle state.

In Step <NUM>, when the UE meets the second predetermined condition, the UE is kept in the inactive state.

That is, the AS state (or called the RRC state) of the UE is kept in the inactive state.

In Step <NUM>, when the UE meets the third predetermined condition, the UE is switched from the inactive state to a connect state.

That is, the AS state (or called the RRC state) of the UE is switched from the inactive state to the connect state.

For Step <NUM>, Step <NUM> and Step <NUM>, only one branch or any two branches may be executed in different embodiments, which will not be limited in the embodiment of the present invention.

From the above, according to the state switching method provided in the embodiment of the present invention, the inactive state is added in the UE, so that the UE in the inactive state may receive and transmit a small data packet service without being switched to the connect state. Thus, the problem of signaling resource waste caused by the fact that the UE is required to be switched between the connect state and the idle state even during transceiving of the small data packet service in <NUM> is solved, thereby enabling the UE in the inactive state to receive and transmit the small data packet service, saving signaling resources and increasing the speed of transceiving a small data packet.

<FIG> is a flow chart showing a state switching method according to an exemplary embodiment. As shown in <FIG>, the state switching method is applied to UE <NUM> in a mobile communication system shown in <FIG>, and the method includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a first predetermined condition or not, the first predetermined condition being that an AS state of the UE does not correspond to a NAS state.

In the embodiment, the AS state of the UE is the inactive state.

The inactive state of an AS of the UE may correspond to one or some certain sub-states of a NAS. The inactive state of the AS corresponds to a state A of the NAS. When the state A of the NAS is switched into a state B, since the state B does not correspond to the inactive state of the AS, there may be the problem of state mismatching between the AS and the NAS.

For a scenario where the AS state of the UE does not correspond to the NAS state, the first predetermined condition specifically includes at least one of the following conditions.

Switching the NAS state of the UE into the EMM-DEREGISTERED state is usually related to local detach of the UE. In other words, after local detach of the UE, the NAS state is switched into the EMM-DEREGISTERED state. Detach includes two types of local detach of the UE and network side detach. A local detach procedure of the UE is involved in the embodiment.

In a possible implementation, the UE cannot find a cell to reside within a period of time, and thus locally deactivates all EPS bearers and executes local detach.

In another possible implementation, the UE transmits a detach request, but the detach request is denied by a residing cell, and a reason for denial is that "access is barred for originating signaling". Then, the UE executes local detach.

In yet another possible implementation, the UE performs a local detach operation after receiving a paging message including an International Mobile Subscriber Identification Number (IMSI) of the UE. A base station may page the UE with a Cell Radio-Network Temporary Identifier (C-RNTI) when storing a context of the UE. The base station may page the UE with the IMSI if losing the context of the UE. If the UE receives the paging message containing the IMSI from the base station, it is indicated that the base station loses the context of the UE, and the UE executes local detach.

During a practical application, during local detach of the UE caused by any factor, the NAS state may be switched from the EMM-REGISTERED state to the EMM-DEREGISTERED state, thereby making the AS and NAS states mismatched. Under such a condition, the UE is required to be switched from the inactive state to the idle state.

The first predetermined condition includes that after the AS of the UE reports that an AS state is the inactive state to the NAS, the AS of the UE receives a second indication of the NAS, the second indication being configured to indicate the UE to establish an RRC connection.

Under such a scenario, the NAS does not directly notify the AS of the NAS state. Instead, the AS is required to actively report the AS state to the NAS, and the state actively reported by the AS to the NAS may be the connect state, the inactive state and the idle state.

After the AS of the UE reports that the AS state is the inactive state to the NAS, the NAS directly indicates a specific operation to the AS.

In an example, the AS periodically reports the AS state to the NAS, or the AS reports the AS state to the NAS when the AS state changes.

Since the AS stores the context in the inactive state, the NAS usually transmits a connection recovery indication to the AS to recover an RRC connection between the UE and the base station according to the stored context. However, if the NAS transmits the second indication to the AS for some reasons, the second indication being configured to indicate the UE to establish the RRC connection with the base station in a creation manner, the UE deletes the stored context, is switched back to the idle state, and transmits a connection establishment request to the base station to establish the RRC connection with the base station in the creation manner.

The first predetermined condition includes that the AS of the UE receives a third indication of the NAS, the third indication being configured to indicate the NAS state to be switched from an EMM-connected state to an EMM-idle state.

The inactive state in the AS state corresponds to the EMM-connected state in the NAS state, or, the inactive state in the AS state is matched with the EMM-connected state in the NAS state. When the NAS state has been switched into the EMM-idle state, the AS is also required to be switched from the inactive state to the idle state.

The first predetermined condition includes that the AS of the UE receives a fourth indication of the NAS, the fourth indication being configured to indicate the NAS state to be switched from an EMM-idle state with an inactive state indication to an EMM-idle state without any inactive state indication.

The inactive state in the AS state corresponds to the EMM-idle state with the inactive state indication in the NAS state, or, the inactive state in the AS state is matched with the EMM-idle state with the inactive state indication in the NAS state.

When the NAS state has been switched from the EMM-idle state with the inactive state indication to the EMM-idle state without the inactive state indication, the AS is also required to be switched from the inactive state to the idle state.

The first predetermined condition includes that the AS of the UE receives a fifth indication of the NAS, the fifth indication being configured to indicate the UE to be switched into the idle state, or, the fifth indication being configured to indicate the AS of the UE to be switched into the idle state.

The first predetermined condition includes that the UE is denied when accessing a new PLMN.

UE which has been registered may also search for a new PLMN under some conditions that a service request or a tracking area update request is denied.

The UE may transmit the tracking area update request to the base station after selecting the new PLMN. If the base station replies that the PLMN is not allowed to be accessed, the NAS state of the UE is switched into the EMM-DEREGISTERED state, and meanwhile, the AS of the UE is switched into the idle state.

From the above, according to the state switching method provided in the embodiment of the present invention, when the AS and NAS states of the UE are mismatched, the UE is switched from the inactive state to the idle state, thereby facilitating to save resources of the UE.

<FIG> is a flow chart showing a state switching method according to an embodiment. As shown in <FIG>, the state switching method is applied to UE <NUM> in an implementation environment shown in <FIG>, and includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a first predetermined condition or not, the first predetermined condition including that when the UE resides in a first-type cell, a decision making result of the UE is that a first connection establishment request is required to be transmitted to the first-type cell.

The first-type cell refers to a cell configured to provide restricted service. The first-type cell is also called an acceptable cell. In an example, the first-type cell may only provide a service such as an emergency call.

When a residing cell of the UE is the first-type cell, if the UE makes such a decision that an RRC connection is required to be re-established according to a service requirement, Step <NUM> is executed.

In an example, transmitting of the first connection establishment request may be determined by an AS, and may also be determined by the AS indicated by a NAS.

That is, the UE deletes a context stored in the inactive state, and an AS state of the UE is switched from the inactive state to the idle state. However, it is noted that the step is an optional step, and the UE may also directly execute Step <NUM> under the condition of being kept in the inactive state.

In Step <NUM>, the UE transmits a connection establishment request to the first-type cell.

That is, after the AS state of the UE is switched into the idle state, the connection establishment request is transmitted to the first-type cell.

It is noted that Step <NUM> to Step <NUM> in the embodiment and the steps in the previous embodiment have no direct sequential association, and may be independently executed respectively.

From the above, according to the state switching method provided in the embodiment of the present invention, when the UE resides in the first-type cell, if being required to access the first-type cell, the UE deletes the stored context, is switched back to the idle state, and then initiates the connection establishment request.

<FIG> is a flow chart showing a state switching method according to an embodiment. As shown in <FIG>, the state switching method is applied to UE <NUM> in a mobile communication system shown in <FIG>, and includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a first predetermined condition or not, the first predetermined condition including that the UE resides in a second-type cell.

The second-type cell refers to a preconfigured cell barring work in the inactive state. Herein, "preconfigured" refers to configuration by access network equipment by transmitting signaling in advance.

During a practical application, a base station preconfigures at least one piece of information in a cell list, area ID (or called a RAN notification area ID), frequency and PLMN barring work in the inactive state to the UE. The UE may reside in a cell in the cell list, or reside in a cell belonging to the area ID, or reside in a cell of the specified frequency or PLMN. Although a residing priority of the UE in the second-type cell is lower than a residing priority in a cell (i.e. a normal cell) allowing work in the inactive state, it is still possible to select the second-type cell when the UE selects the residing cell.

If the UE resides in the second-type cell, the UE deletes a context stored in the inactive state, and enters the idle state.

In an example, after the UE is switched from the inactive state to the idle state, if there is made such a service decision that an RRC connection is required to be established, the UE transmits a second connection establishment request to the second-type cell, the second connection establishment request being configured to request to access the second-type cell.

From the above, according to the state switching method provided in the embodiment of the present invention, when the UE resides in the cell barring work in the inactive state, switching to the idle state may save computing resources of the UE.

In other optional embodiments of the present invention, when the UE meets any one of the following other first predetermined conditions in the inactive state, the UE is switched from the inactive state to the idle state.

In an example, the first predetermined condition includes that a SIM card is not inserted into the UE. The SIM card being not inserted includes that an original state is uninserted, or the SIM card which has been inserted is extracted.

In an example, the first predetermined condition includes that the UE does not find any cell where the UE can reside.

In an example, the first predetermined condition includes that a duration for which the UE does not find any cell where the UE can reside reaches a first predetermined time length.

In an example, the first predetermined time length is preconfigured by a network side, or is self-defined by the UE.

In an example, the first predetermined condition includes that the UE receives an access denial message after transmitting a third connection establishment request. The third connection establishment request is configured to request to enable the UE to access the residing cell.

The UE transmits the third connection establishment request to the base station, the base station transmits a connection establishment denial message to the UE, and the UE is switched from the inactive state to the idle state according to the connection establishment denial message.

In an example, the first predetermined condition includes that the UE receives an access denial message containing a sixth indication after transmitting the third connection establishment request. The third connection establishment request is configured to request to enable the UE to access the residing cell, and the sixth indication is configured to indicate the UE to be switched into the idle state.

In an example, after the UE transmits the third connection establishment request to the base station, the base station transmits the access denial message to the UE, the access denial message containing an indication of entering the idle state, and the UE is switched into the idle state according to the access denial message.

In an example, the first predetermined condition includes that the UE receives an access denial message not containing a seventh indication after transmitting the third connection establishment request. The third connection establishment request is configured to request to enable the UE to access the residing cell, and the seventh indication is configured to indicate the UE to be kept in the inactive state.

The UE transmits the third connection establishment request to the base station, the base station transmits to the UE the access denial message not containing any indication about that the UE is kept in the inactive state. Since the base station does not clearly indicate that the UE is kept in the inactive state, the UE is switched into the idle state according to the access denial message.

In an example, the first predetermined condition includes that the UE receives an update denial message after transmitting a RAN side location area update request. The RAN side location area update request is configured to request to update a RAN side location area of the UE. Since the base station denies location area update of the UE, the UE is switched into the idle state according to the update denial message.

In an example, the first predetermined condition includes that the number of times for which update continuously fails after the UE initiates the RAN side location area update request reaches the predetermined number of times.

During practical implementation, when the UE fails to transmit the RAN side location area update request or does not receive any message returned by the base station, the UE may not complete update.

In an example, the first predetermined condition includes that after accessing another network except a target network in a cell reselection process, the UE re-accesses the target network, and a context stored by the UE in the inactive state is lost. The target network is a network supporting the UE to work in the inactive state. In an example, the target network is a <NUM> network.

During a practical application, a wireless network A is a network barring work in the inactive state, and a wireless network B is a network allowing work in the inactive state. When the UE is switched from the wireless network A to the wireless network B, if the context of the UE is lost, the UE is required to be switched back to the idle state.

In an example, the first predetermined condition includes that the UE accesses a first predetermined network in the cell reselection process. The first predetermined network refers to a preconfigured network barring the context of the UE kept in the inactive state.

In an example, the first predetermined condition includes that a duration for which the UE is kept in the inactive state reaches a second predetermined time length. The second predetermined time length refers to a preconfigured maximum time length for which the UE is allowed to be kept in the inactive state.

In an example, the second predetermined time length is a time length preconfigured by the system or determined by the UE and the base station.

<FIG> is a flow chart showing a state keeping method according to an embodiment. As shown in <FIG>, the state keeping method is applied to UE <NUM> in a mobile communication system shown in <FIG>, and includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a second predetermined condition or not, the second predetermined condition including that the UE resides in a first-type cell.

The first-type cell refers to a cell providing restricted service.

That is, when the UE resides in the first-type cell, an AS of the UE is kept in the inactive state.

In an example, after the UE resides in the first-type cell, if the UE is required to access the first-type cell, the following two manners may be adopted.

According to the first manner, the UE transmits a first connection recovery request, the first connection recovery request being configured to recover access to the first-type cell according to a context stored in the inactive state.

According to the second manner, the UE deletes the context stored in the inactive state, the UE is switched from the inactive state into an idle state, and the UE transmits a first connection establishment request, the first connection establishment request being configured to request to access the first-type cell.

In an example, it is determined by the AS or is determined by the AS indicated by a NAS of the UE whether the UE transmits the first connection recovery request or the first connection establishment request.

In an example, the UE does not transmit a RAN side location area update request when residing in the first-type cell.

If the UE does not transmit the RAN side location area update request when residing in the first-type cell, a base station cannot learn about a residing location area of the UE within a period of time. The RAN side location area update request is transmitted until the UE accesses a suitable cell.

In an example, the UE transmits the RAN side location area update request when accessing the first-type cell for the first time.

Different from the previous condition, the UE transmits the RAN side location area update request only when accessing the first-type cell for the first time. Although the first-type cell does not provide a data transceiving service, a base station side may learn about the residing location area of the UE.

In an example, when the UE accesses a third-type cell after residing in the first-type cell, the UE transmits the RAN side location area update request, the third-type cell referring to a suitable cell.

The third-type cell is a cell capable of normally transceiving data.

From the above, according to the state keeping method provided in the embodiment of the present invention, the UE is kept in the inactive state when residing in the first-type cell, so that the UE is not required to perform state switching when accessing the third-type cell again, and may recover the RRC connection again according to the stored context, thereby avoiding the state Ping-Pong problem caused by mobility of the UE between the first-type cell and the third-type cell.

<FIG> is a flow chart showing a state keeping method according to an embodiment. As shown in <FIG>, the state keeping method is applied to UE <NUM> in an implementation environment shown in <FIG>, and includes the following steps.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a second predetermined condition or not, the second predetermined condition including that the UE resides in a second-type cell.

The second-type cell refers to a preconfigured cell barring execution of a predetermined service in the inactive state.

In Step <NUM>, when the UE is in the inactive state and meets the second predetermined condition, the UE is kept in the inactive state.

In an example, when the UE is kept in the inactive state, no data transceiving service is executed.

In an example, after the UE resides in the second-type cell, under a service requirement (the UE is required to transmit data), the UE transmits a second connection recovery request, the second connection recovery request being configured to request to access the second-type cell according to a context of the UE in the inactive state.

In an example, the UE does not transmit a RAN side location area update request when residing in the second-type cell.

If the UE does not transmit the RAN side location area update request when residing in the second-type cell, a base station cannot learn about a residing location area of the UE within a period of time, and the RAN side location area update request is transmitted after the UE accesses a cell allowing work in the inactive state.

In an example, the UE transmits the RAN side location area update request when accessing the second-type cell for the first time.

In an example, if a RAN side location area of the UE changes, the UE transmits the RAN side location area update request when accessing a fourth-type cell, wherein the fourth-type cell refers to a preconfigured cell allowing work in the inactive state.

In an example, if the UE is switched into an idle state, the UE transmits the RAN side location area update request when accessing the fourth-type cell.

In an example, if the UE receives an update denial message after transmitting the RAN side location area update request, the UE transmits the RAN side location area update request when accessing the fourth-type cell.

In an example, if the UE receives an accepting message containing an eighth indication after transmitting the RAN side location area update request, the UE transmits the RAN side location area update request when accessing the fourth-type cell, the eighth indication being configured to indicate that the UE is barred to perform a data transceiving service in the inactive state and the accepting message being a response received after the UE transmits the RAN side location area update request.

In an example, the UE does not transmit the RAN side location area update request when residing in the second-type cell, and the UE transmits the RAN side location area update request when accessing the fourth-type cell.

From the above, according to the state keeping method provided in the embodiment of the present invention, the UE is kept in the inactive state when residing in the second-type cell, so that the UE may recover the RRC connection through the stored context, thereby saving signaling resources at a network side.

In other optional embodiments of the present invention, when the UE meets any one of the following other second predetermined conditions in the inactive state, the UE is kept in the inactive state.

In an example, the second predetermined condition includes that after the UE is denied to access a first PLMN, the UE resides in the first-type cell at first, and the UE successfully accesses a second PLMN and resides in the third-type cell according to an indication of a NAS.

Herein, the first-type cell refers to a cell providing restricted service, and the third-type cell may refer to a suitable cell which can provide normal service.

In an example, the second predetermined condition includes that the UE does not find any cell where the UE can reside. At this moment, the UE is kept in the inactive state, which may be called any cell selection state in the inactive state. Of course, as an alternate solution, if not finding any cell where the UE can reside, the UE may also be switched from the inactive state to an idle state to enter any cell selection state in the idle state.

In an example, the second predetermined condition includes that the UE receives an access denial message containing a ninth indication after transmitting a second connection establishment request in the inactive state. The second connection establishment request is configured to request to enable the UE to access a residing cell, and the ninth indication is configured to indicate the UE to be kept in the inactive state.

After the UE transmits the second connection establishment request to the base station, the base station transmits to the UE an access denial message clearly indicating that the UE is kept in the inactive state, and the UE is kept in the inactive state according to the access denial message.

In an example, the second predetermined condition includes that the UE receives an accepting message after transmitting the RAN side location area update request, the accepting message containing a tenth indication and the tenth indication being configured to indicate that the UE is barred to execute the data transceiving service in the inactive state. Herein, the accepting message is a response received after the UE transmits the RAN side location area update request.

In an example, the second predetermined condition includes that the UE receives an accepting message after transmitting the RAN side location area update request, and successfully performs RAN side location area update according to the accepting message. Herein the accepting message is a response received after the UE transmits the RAN side location area update request.

In an example, the second predetermined condition includes that after the UE transmits a RAN side location area update request containing a predetermined ID, the UE receives an accepting message including a denial indication, and successfully performs RAN side location area update according to the accepting message. Herein the predetermined ID is configured to represent that the UE requests to enter a connect state, the denial indication is configured to indicate that the UE is barred to enter the connect state, and the accepting message is a response received after the UE transmits the RAN side location area update request.

In an example, the second predetermined condition includes that when the number of times for which update continuously fails after the UE transmits the RAN side location area update request reaches a first predetermined number of times, the UE retransmits the RAN side location area update request and recounts the number of times after waiting for a third predetermined time length.

In an example, the third predetermined time length is a time length preconfigured by the system or agreed by the UE and the base station.

In an example, the second predetermined condition includes that when the number of times for which update continuously fails after the UE transmits the RAN side location area update request reaches a second predetermined number of times, the UE stops updating and when the UE is required to access the residing cell, retransmits the RAN side location area update request or initiates a third connection recovery request. Herein the third connection recovery request is configured to request to recover access to the residing cell according to the context stored in the inactive state.

In an example, the second predetermined condition includes that when the number of times for which update continuously fails after the UE transmits the RAN side location area update request reaches a third predetermined number of times, the UE stops updating and reinitiates the RAN side location area update request when the UE accesses a new cell.

In an example, the second predetermined condition includes that the UE accesses another network except a target network in a cell reselection process. Herein the target network is a network supporting the UE to work in the inactive state.

In an example, the second predetermined condition includes that the UE accesses the other network except the target network in the cell reselection process, and a time length for which the other network has been accessed is within a fourth predetermined time length.

In an example, the second predetermined condition includes that the UE accesses a second predetermined network in the cell reselection process. Herein the second predetermined network refers to a preconfigured network allowing the context of the UE in the inactive state to be kept, and the second predetermined network belongs to another network except the target network.

In an example, the second predetermined condition includes that a duration for which the UE is kept in the inactive state is within a fifth predetermined time length. Herein the fifth predetermined time length refers to a preconfigured maximum time length for which the UE is allowed to be kept in the inactive state.

In an example, if the base station preconfigures the time length for which the UE is kept in the inactive state, the base station transmits a response message of the RAN side location area update request to update information about a duration for which the UE is kept in the inactive state. After the information about the duration for which the UE is kept in the inactive state is updated, a timer is retimed.

In a possible implementation, if the UE is switched from the inactive state to the connect state, the duration for which the UE is kept in the inactive state is invalid.

In an example, the second predetermined condition includes that the UE fails to initiate connection recovery. That is, the UE does not receive any response or receives a denial response after transmitting the RRC connection recovery request.

In an example, the second predetermined condition includes that the UE fails to transmit data or fails to receive data in the inactive state.

From the above, according to the state keeping method provided in the embodiment of the present invention, the UE is kept in the inactive state, so that the UE is not required to be switched into the connect state during transceiving of a small data packet service, thereby saving signaling resources.

In Step <NUM>, when the UE is in an inactive state, it is detected whether the UE meets a third predetermined condition or not, the third predetermined condition including that the UE transmits a RAN side location area update request containing a predetermined ID, receives an accepting message and successfully performs RAN side location area update according to the accepting message.

The RAN side location area update request contains the predetermined ID, and the predetermined ID is configured to request to enter a connect state. That is, when the UE is in the inactive state, if switching back to the connect state is required according to a service requirement, the UE contains the predetermined ID in the RAN side location area update request in a process of transmitting the RAN side location area update request to a base station, and the predetermined ID is configured to represent that the UE requests to enter the connect state.

At this moment, the base station may feedback the accepting message. The accepting message not only represents that location area update of the UE is accepted, but also indicates that the UE is allowed to enter the connect state.

In an example, the accepting message contains an eleventh indication, the eleventh indication being configured to indicate that the UE is allowed to enter the connect state. In an example, the accepting message does not contain any indication, and the accepting message is configured to implicitly indicate that the UE is allowed to enter the connect state. In other words, if the base station does not contain any indication in the accepting message, it is indicated that the UE is allowed to enter the connect state. If the base station contains a denial indication in the accepting message, it is indicated that the UE is not allowed to enter the connect state.

After receiving the accepting message, the UE successfully performs RAN side location area update according to the accepting message.

In an example, when the accepting message indicates that the UE is allowed to enter the connect state, the UE is switched from the inactive state to the connect state.

In an optional embodiment based on <FIG>, the RAN side location area update request transmitted by the UE to access network equipment or a completion message corresponding to the RAN side location area update request further contains a NAS request. Such a NAS message is configured to trigger NAS location area update or EPC side location area update. The completion message is transmitted after the UE successfully performs RAN side location area update.

In the optional embodiment, a mechanism of containing and transmitting the NAS message is triggered after a NAS of the UE determines that the UE enters a new location update area. That is, before the UE transmits the RAN side location area update request containing the predetermined ID and the NAS message to the access network equipment, the method further includes the following step.

The NAS of the UE transmits the NAS message to an AS, or, the NAS of the UE indicates the AS to establish an RRC connection, or, the NAS of the UE indicates the AS to recover the RRC connection.

From the above, according to the state switching method provided in the embodiment of the present invention, the predetermined ID is contained in the RAN side location area update request transmitted by the UE, and when the accepting message transmitted by the base station clearly indicates connection recovery or does not include a default connection recovery indication, the UE is switched from the inactive state to the connect state, and the UE may receive and transmit each data service in the connect state.

It is noted that state names and message names mentioned in each of the embodiments are schematic, and are not limited in the embodiments.

The below is the device embodiments of the present invention, which may be adopted to execute the method embodiments of the present invention. Details undisclosed in the device embodiments of the present invention may refer to the method embodiments of the present invention.

<FIG> is a block diagram of a state switching device according to an embodiment. As shown in <FIG>, the state switching device is applied to UE <NUM> in a mobile communication system shown in <FIG>, and the state switching device includes but not limited to a processing module <NUM>.

The processing module <NUM> is configured to, when the UE is in an inactive state and meets a first predetermined condition, switch the UE from the inactive state to an idle state.

The processing module <NUM> is configured to, when the UE is in the inactive state and meets a second predetermined condition, keep the inactive state.

The processing module <NUM> is configured to, when the UE is in the inactive state and meets a third predetermined condition, switch the UE from the inactive state to a connect state.

Herein the inactive state is an intermediate state between the connect state and the idle state.

In an example, the first predetermined condition includes that an AS of the UE receives a first indication of a NAS, the first indication being configured to indicate a NAS state to be switched from an EMM-REGISTERED state to an EMM-DEREGISTERED state.

In an example, the first predetermined condition includes that after the AS of the UE reports to the NAS that an AS state is the inactive state, the AS of the UE receives a second indication of the NAS, the second indication being configured to indicate the UE to establish an RRC connection.

In an example, the first predetermined condition includes that the AS of the UE receives a third indication of the NAS, the third indication being configured to indicate the NAS state to be switched from an EMM-connected state to an EMM-idle state.

Herein the inactive state in the AS state corresponds to the EMM-connected state in the NAS state.

In an example, the first predetermined condition includes that the AS of the UE receives a fourth indication of the NAS, the fourth indication being configured to indicate the NAS state to be switched from an EMM-idle state with an inactive state indication to an EMM-idle state without any inactive state indication.

Herein the inactive state in the AS state corresponds to the EMM-idle state with the inactive state indication in the NAS state.

In an example, the first predetermined condition includes that the AS of the UE receives a fifth indication of the NAS, the fifth indication being configured to indicate the UE to be switched into the idle state.

In an example, the first predetermined condition includes that the UE is denied when accessing a new PLMN.

In an example, the first predetermined condition includes that a SIM card is not inserted into the UE.

In an example, the first predetermined condition includes that when the UE resides in a first-type cell, a decision making result of the UE is that a first connection establishment request is required to be transmitted to the first-type cell.

Herein the first-type cell refers to a cell configured to provide restricted service, and the first connection establishment request is configured to request to access the first-type cell.

In an example, the first predetermined condition includes that the UE does not find any cell where the UE can reside; or, a duration for which the UE does not find any cell where the UE can reside reaches a first predetermined time length.

In an example, the first predetermined condition includes that the UE resides in a second-type cell.

Herein the second-type cell refers to a preconfigured cell barring work in the inactive state.

In an example, the device further includes a transmitting module <NUM>.

The transmitting module <NUM> is configured to transmit, by the UE, a second connection establishment request, the second connection establishment request being configured to request to access the second-type cell.

In an example, the first predetermined condition includes that the UE receives an access denial message after transmitting a third connection establishment request.

Herein the third connection establishment request is configured to request to enable the UE to access a residing cell.

In an example, the first predetermined condition includes that the UE receives an access denial message containing a sixth indication after transmitting the third connection establishment request, the third connection establishment request being configured to request to enable the UE to access the residing cell, and the sixth indication being configured to indicate the UE to be switched into the idle state; or, the UE receives an access denial message not containing a seventh indication after transmitting the third connection establishment request, the third connection establishment request being configured to request to enable the UE to access the residing cell, and the seventh indication being configured to indicate the UE to be kept in the inactive state.

In an example, the first predetermined condition includes that the UE receives an update denial message after transmitting a RAN side location area update request.

Herein the RAN side location area update request is configured to request to update a RAN side location area of the UE.

In an example, the first predetermined condition includes that the number of times for which update continuously fails after the UE initiates the RAN side location area update request reaches a predetermined number of times.

Herein the RAN side location area update request is configured to request to update the RAN side location area of the UE.

In an example, the first predetermined condition includes that after accessing another network except a target network in a cell reselection process, the UE re-accesses the target network, and a context stored by the UE in the inactive state is lost.

Herein the target network is a network supporting the UE to work in the inactive state.

In an example, the first predetermined condition includes that the UE accesses a first predetermined network in the cell reselection process.

Herein the first predetermined network refers to a preconfigured network barring the context of the UE kept in the inactive state.

In an example, the first predetermined condition includes that a duration for which the UE is kept in the inactive state reaches a second predetermined time length.

Herein the second predetermined time length refers to a preconfigured maximum time length for which the UE is allowed to be kept in the inactive state.

In an example, the second predetermined condition includes that the UE resides in the first-type cell.

Herein the first-type cell refers to the cell providing restricted service.

In an example, the transmitting module <NUM> is configured to transmit, by the UE, the first connection recovery request, the first connection recovery request being configured to recover access to the first-type cell according to the context stored in the inactive state.

Alternatively, the transmitting module <NUM> is configured to delete, by the UE, the context stored in the inactive state, switch the UE from the inactive state into the idle state and transmit, by the UE, the first connection establishment request, the first connection establishment request being configured to request to access the first-type cell.

In an example, the transmitting module <NUM> is configured to transmit no RAN side location area update request when residing in the first-type cell.

Alternatively, the transmitting module <NUM> is configured to transmit the RAN side location area update request when accessing the first-type cell for the first time.

In an example, the transmitting module <NUM> is further configured to, when the UE accesses a third-type cell, transmit the RAN side location area update request, the third-type cell referring to a suitable cell.

In an example, the second predetermined condition includes that after the UE is denied to access a first PLMN, the UE resides in the first-type cell at first, and the UE successfully accesses a second PLMN and resides in the third-type cell according to an indication of the NAS.

Herein the first-type cell refers to the cell providing the restricted service, and the third-type cell refers to the suitable cell.

In an example, the second predetermined condition includes that the UE does not find any cell where the UE can reside.

In an example, the second predetermined condition includes that the UE resides in the second-type cell.

Herein the second-type cell refers to a preconfigured cell barring execution of a predetermined service in the inactive state.

In an example, the transmitting module <NUM> is configured to, when residing in the second-type cell, transmit no RAN side location area update request.

Alternatively, the transmitting module <NUM> is further configured to, when accessing the second-type cell for the first time, transmit the RAN side location area update request.

Alternatively, the transmitting module <NUM> is further configured to, if a RAN side location area of the UE changes, transmit the RAN side location area update request when accessing a fourth-type cell.

Alternatively, the transmitting module <NUM> is further configured to, if the UE is switched into the idle state, transmit the RAN side location area update request when accessing the fourth-type cell.

Alternatively, the transmitting module <NUM> is further configured to, if the update denial message is received after the RAN side location area update request is transmitted, transmit the RAN side location area update request when accessing the fourth-type cell.

Alternatively, the transmitting module <NUM> is further configured to, if the UE receives an accepting message containing an eighth indication after transmitting the RAN side location area update request, transmit the RAN side location area update request when accessing the fourth-type cell, the eighth indication being configured to indicate that the UE is barred to perform the data transceiving service in the inactive state and the accepting message being a response received after the UE transmits the RAN side location area update request.

Alternatively, the transmitting module <NUM> is further configured to transmit no RAN side location area update request when the UE resides in the second-type cell, and transmit the RAN side location area update request when the UE accesses the fourth-type cell.

Herein the fourth-type cell refers to a preconfigured cell allowing work in the inactive state.

In an example, the processing module <NUM> is further configured to execute no data transceiving service when the UE is kept in the inactive state.

In an example, the transmitting module <NUM> is configured to transmit, by the UE, a second connection recovery request, the second connection recovery request being configured to request to recover access to the second-type cell according to the context of the UE in the inactive state.

In an example, the second predetermined condition includes that the UE receives an access denial message containing a ninth indication after transmitting a second connection establishment request.

Herein the second connection establishment request is configured to request to enable the UE to access a residing cell, and the ninth indication is configured to indicate the UE to be kept in the inactive state.

In an example, the second predetermined condition includes that the UE receives an accepting message after transmitting the RAN side location area update request, the accepting message containing a tenth indication and the tenth indication being configured to indicate that the UE is barred to execute the data transceiving service in the inactive state.

Herein the accepting message is a response received after the UE transmits the RAN side location area update request.

In an example, the second predetermined condition includes that the UE receives an accepting message after transmitting the RAN side location area update request, and successfully performs RAN side location area update according to the accepting message.

Herein the accepting message is a response received after the UE transmits the RAN side location area update request, the RAN side location area update request does not contain a predetermined ID, and the predetermined ID is configured to request to enter the connect state.

In an example, the second predetermined condition includes that after the UE transmits a RAN side location area update request containing the predetermined ID, the UE receives an accepting message including a denial indication, and successfully performs RAN side location area update according to the accepting message.

Herein the predetermined ID is configured to represent that the UE requests to enter the connect state, the denial indication is configured to indicate that the UE is barred to enter the connect state, and the accepting message is a response received after the UE transmits the RAN side location area update request.

In an example, the second predetermined condition includes that when the number of times for which update continuously fails after the UE transmits the RAN side location area update request reaches a second predetermined number of times, the UE stops updating and when the UE is required to access the residing cell, retransmits the RAN side location area update request or initiates a third connection recovery request.

Herein the third connection recovery request is configured to request to recover access to the residing cell according to the context stored in the inactive state.

In an example, the second predetermined condition includes that the UE accesses another network except the target network in the cell reselection process. The target network is the network supporting the UE to work in the inactive state.

Herein the target network is the network supporting the UE to work in the inactive state.

In an example, the second predetermined condition includes that the UE accesses a second predetermined network in the cell reselection process.

Herein the second predetermined network refers to a preconfigured network allowing the context of the UE in the inactive state to be kept, and the second predetermined network belongs to another network except the target network.

In an example, the second predetermined condition includes that a duration for which the UE is kept in the inactive state is within a fifth predetermined time length.

Herein the fifth predetermined time length refers to a preconfigured maximum time length for which the UE is allowed to be kept in the inactive state.

In an example, the second predetermined condition includes that the UE fails to initiate connection recovery.

In an example, the third predetermined condition includes that the UE transmits the RAN side location area update request, and receives the accepting message; and the UE successfully performs RAN side location area update according to the accepting message.

Herein the RAN side location area update request contains the predetermined ID, the predetermined ID is configured to request to enter the connect state, and the accepting message is configured to indicate that location area update of the UE is accepted and the UE is allowed to enter the connect state.

In an example, the RAN side location area update request or a completion message corresponding to the RAN side location area update request further contains a NAS request.

The processing module is further configured to, before the UE transmits the RAN side location area update request and receives the accepting message, transmit the NAS message to the AS through the NAS of the UE, or, indicate the AS to establish the RRC connection through the NAS of the UE, or, indicate the AS to recover the RRC connection through the NAS of the UE.

In an example, the accepting message contains an eleventh indication, the eleventh indication being configured to indicate that the UE is allowed to enter the connect state; or, the accepting message does not contain any indication, and the accepting message is configured to implicitly indicate that the UE is allowed to enter the connect state.

From the above, according to the state switching device provided in the embodiment of the present invention, the inactive state is added in the UE, so that the UE in the inactive state may receive and transmit a small data packet service without being switched to the connect state. Therefore, the problem of signaling resource waste caused by the fact that the UE is required to be switched between the connect state and the idle state even during transceiving of the small data packet service in <NUM> is solved, thereby enabling the UE in the inactive state to receive and transmit the small data packet service and saving signaling resources.

With respect to the devices in the above embodiment, the specific manners for performing operations for individual modules therein have been described in detail in the embodiments regarding the methods, which will not be elaborated herein.

An exemplary embodiment of the present invention provides UE, which may implement a state switching method provided by the present invention, the UE including a processor and a memory configured to store instructions executable by the processor.

The processor is configured to when the UE is in an inactive state and meets a first predetermined condition, switch the UE from the inactive state to an idle state.

Herein the inactive state is an intermediate state between a connect state and the idle state.

An exemplary embodiment of the present invention provides UE, which may implement a state keeping method provided by the present invention, the UE including a processor and a memory configured to store instructions executable by the processor.

The processor is configured to when the UE is in an inactive state and meets a second predetermined condition, keep the UE in the inactive state.

Herein the inactive state is an intermediate state between a connect state and an idle state.

The processor is configured to when the UE is in an inactive state and meets a third predetermined condition, switch the UE from the inactive state to a connect state.

Herein the inactive state is an intermediate state between the connect state and an idle state.

<FIG> is a block diagram of UE according to an embodiment. The UE <NUM> may be a mobile phone, a computer, a digital broadcast terminal, a messaging device, a gaming console, a tablet, a medical device, exercise equipment, a personal digital assistant or the like.

Referring to <FIG>, the UE <NUM> may include one or more of the following components: a processing component <NUM>, a memory <NUM>, a power component <NUM>, a multimedia component <NUM>, an audio component <NUM>, an Input/Output (I/O) interface <NUM>, a sensor component <NUM>, and a communication component <NUM>.

The processing component <NUM> typically controls overall operations of the UE <NUM>, such as the operations associated with display, telephone calls, data communications, camera operations, and recording operations. The processing component <NUM> may include one or more processors <NUM> to execute instructions to perform all or part of the steps in the abovementioned method. Moreover, the processing component <NUM> may include one or more modules which facilitate interaction between the processing component <NUM> and the other components. For instance, the processing component <NUM> may include a multimedia module to facilitate interaction between the multimedia component <NUM> and the processing component <NUM>.

The memory <NUM> is configured to store various types of data to support the operation of the UE <NUM>. Examples of such data include instructions for any application programs or methods operated on the UE <NUM>, contact data, phonebook data, messages, pictures, video, etc. The memory <NUM> may be implemented by any type of volatile or non-volatile memory devices, or a combination thereof, such as a Static Random Access Memory (SRAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), an Erasable Programmable Read-Only Memory (EPROM), a Programmable Read-Only Memory (PROM), a Read-Only Memory (ROM), a magnetic memory, a flash memory, and a magnetic or optical disk.

The power component <NUM> provides power for various components of the UE <NUM>. The power component <NUM> may include a power management system, one or more power supplies, and other components associated with the generation, management and distribution of power for the UE <NUM>.

The multimedia component <NUM> includes a screen providing an output interface between the UE <NUM> and a user. In some embodiments, the screen may include a Liquid Crystal Display (LCD) and a Touch Panel (TP). If the screen includes the TP, the screen may be implemented as a touch screen to receive an input signal from the user. The TP includes one or more touch sensors to sense touches, slides and gestures on the TP. The touch sensors may not only sense a boundary of a touch or slide action, but also detect a duration and pressure associated with the touch or slide action. The front camera and/or the rear camera may receive external multimedia data when the UE <NUM> is in an operation mode, such as a photographing mode or a video mode. Each of the front camera and the rear camera may be a fixed optical lens system or have focusing and optical zooming capabilities.

The audio component <NUM> is configured to output and/or input an audio signal. The audio component <NUM> includes a Microphone (MIC), and the MIC is configured to receive an external audio signal when the UE <NUM> is in the operation mode, such as a call mode, a recording mode and a voice recognition mode. The received audio signal may be further stored in the memory <NUM> or transmitted through the communication component <NUM>. In some embodiments, the audio component <NUM> further includes a speaker configured to output the audio signal.

The sensor component <NUM> includes one or more sensors configured to provide status assessment in various aspects for the UE <NUM>. For instance, the sensor component <NUM> may detect an on/off status of the UE <NUM> and relative positioning of components, such as a display and small keyboard of the device <NUM>, and the sensor component <NUM> may further detect a change in a position of the UE <NUM> or a component of the UE <NUM>, presence or absence of contact between the user and the UE <NUM>, orientation or acceleration/deceleration of the UE <NUM> and a change in temperature of the UE <NUM>.

The communication component <NUM> is configured to facilitate wired or wireless communication between the UE <NUM> and other equpment. The UE <NUM> may access a communication-standard-based wireless network, such as a Wireless Fidelity (WiFi) network, a <NUM> or <NUM> network or a combination thereof. In an embodiment, the communication component <NUM> receives a broadcast signal or broadcast associated information from an external broadcast management system through a broadcast channel. In an embodiment, the communication component <NUM> further includes a Near Field Communciation (NFC) module to facilitate short-range communication. The NFC module may be implemented based ona Radio Frequency Identification (RFID) technology, an Infrared Data Association (IrDA) technology, an Ultra-WideBand (UWB) technology, a Bluetooth (BT) technology and another technology.

In an embodiment, the UE <NUM> may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, micro-controllers, microprocessors or other electronic components, and is configured to execute the state switching method or state keeping method provided by each method embodiment.

Claim 1:
A state keeping method, comprising:
when a User Equipment, UE (<NUM>), is in an inactive state and meets a second predetermined condition, keeping (<NUM>) the UE (<NUM>) in the inactive state,
wherein the inactive state is an intermediate state between a connect state and an idle state,
the method characterized in that
the second predetermined condition comprises that the UE (<NUM>) fails to find any cell available for the UE (<NUM>) to reside; and
in that the method further comprises:
if a Radio Access Network, RAN, side location area of the UE (<NUM>) changes, transmitting, by the UE (<NUM>), a RAN side location area update request when accessing a fourth-type cell, wherein the fourth-type cell refers to a preconfigured cell allowing work in the inactive state.