Patent ID: 12192946

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present disclosure.

FIG.1illustrates a schematic wireless communication system100according to some embodiments of the present disclosure.

Referring toFIG.1, a wireless communication system100may include a base station (e.g., BS120) and some UEs (e.g., UE110A and UE110B). Although, for simplicity, merely one BS120and two UEs are illustrated inFIG.1, it is contemplated that wireless communication system100may also include more BSs120and more or fewer UEs in and outside of the coverage of the BSs120in some other embodiments of the present disclosure.

The UEs and the base station may support communication based on, for example, 3G, Long-Term Evolution (LTE), LTE-Advanced (LTE-A), New Radio (NR), or other suitable protocol(s). For example, the BS120may include an eNB or a gNB. The UE110A may include, for example, but is not limited to, a computing device, a wearable device, a mobile device, an IoT device, etc. The UE110B may include a device that is the same or similar to the UE110A. The UE110B may also include a device different from the UE110A. Persons skilled in the art should understand that as technology develops and advances, the terminologies described in the present disclosure may change, but should not affect or limit the principles and spirit of the present disclosure.

According to the 3rd Generation Partnership Project (3GPP), a UE (e.g., UE110A or UE110B) may be in one of the following state: RRC-IDLE state, RRC_CONNECTED state, and RRC_INACTIVE state, at a given time. In RRC_INACTIVE state, a UE does not have an RRC connection with the Radio Access Network (RAN, e.g., BS120). However, the RAN keeps a connection with the core network for the UE. Therefore, RRC_INACTIVE state may achieve power saving with acceptable access latency. The specific characteristics of RRC-IDLE state, RRC_CONNECTED state, and RRC_INACTIVE state are defined in 3GPP specifications. The UE110A and UE110B may be in an idle mode corresponding to the RRC_IDLE state, an inactive mode corresponding to the RRC_INACTIVE state, or a connected mode corresponding to the RRC_CONNECTED state.

The BS120may communicate with a Core Network (CN) (not shown inFIG.1), and may operate or work under the control of an Access and Mobility Management Function (AMF) (not shown inFIG.1), which functions as a part of the core network. The BS120may define one or more cells, and each cell may have a coverage area130. In the exemplary wireless communication system100, UE110A is within the coverage of the BS120(i.e., in-coverage), and UE110B is outside the coverage of the BS120(i.e., out-of-coverage).

AlthoughFIG.1shows that the UE110B is outside of the coverage of the BS120for simplicity, it is contemplated that the UE110B may also be within the coverage of the BS120in some other embodiments of the present disclosure.

The UE110B may want to communicate with the network to receive services. However, UE110B may not be able to communicate with the network because, for example, it is outside the coverage of the base station or it is incapable of communicating with the base station. One of some solutions to resolve the above problem is to relay via another UE which is located within the coverage of the base station or in communication with the base station. For example, UE110B may access the BS120via the UE110A. In this case, UE110A may act as a relay node relaying messages and data between UE110B and BS120(or the core network). The UE110A may be referred to as a relay UE, and the UE110B may be referred to as a remote UE or a child node of the UE110A.

More details on the procedure of handling communications between a remote UE, a relay UE, and the network or the BS will be described in detail in the following text in combination with the appended drawings.

In a wireless communication system, a communication device may need to register with a network to receive services. A communication device may also need to register its presence in a registration area periodically or when entering a new tracking area. A registration Area is an area in which a communication device may roam without a need to perform location registration, which is a Non-Access Stratum (NAS) procedure. In other words, the communication device may initiate a network registration procedure under, but is not limited to, one of the following conditions:initial registration with the wireless communication system (e.g., when the communication device is powered up);upon a change in the registration area (e.g., when the communication device moves to a new Tracking Area (TA) outside the communication device's original registration area); orperiodic registration update (e.g., due to a predefined time period of inactivity).

The above three conditions may be referred to as initial registration, registration area update, and periodic registration update, respectively.

FIG.2illustrates a flow chart of an exemplary procedure200of performing core network registration for a communication device according to some embodiments of the present disclosure. The exemplary procedure200is applicable to the above three types of registration, i.e., initial registration, registration area update, and periodic registration update, and other types of registration.

The exemplary procedure200shows a procedure of a communication device (e.g., communication device210) communicating with a base station (e.g., BS220), which operates under the control of a core network entity (e.g., AMF230). In some examples, the communication device210may function as the communication device110A or the communication device110B inFIG.1. The BS220may function as the BS120inFIG.1.

Referring toFIG.2, in operation251, the communication device210may transmit a registration request message to the BS220. The registration request message may include a registration type. The registration type may indicate whether the communication device210intends to perform an initial registration, a registration area update, a periodic registration update, or other types of registration. The registration request message may include the identity of the communication device210.

In operation253, the BS220may transfer the registration request message to the AMF230. The registration request message may include the identity of the communication device210. After receiving the registration request message from the BS220, the AMF230may transmit, in operation255, a registration accept message to the BS220. The registration accept message may indicate that the registration request of the communication device has been accepted. The registration accept message may include the identity of the communication device210.

In some embodiments of the present disclosure, the registration accept message may include registration information. In some embodiments, the registration information may indicate at least one registration area (e.g., tracking area) in which the serving cell (e.g., the BS220) is located. A tracking area may be identified by a Tracking Area Code (TAC).

In some embodiments of the present disclosure, the registration accept message may not indicate the registration area or the tracking area, which may suggest that a last registration area allocated to the communication device is still valid. In other words, the communication device is within the last registration area.

In operation257, the BS220may transfer the registration accept message to the communication device210. In operation259, the communication device210may transmit a registration complete message to the BS220. The registration complete message may include the identity of the communication device210. In operation261, the BS220may transmit the registration complete message to the AMF230. The specific definitions of the above messages are defined in 3GPP specification TS 23.502.

It should be appreciated by persons skilled in the art that some of the operations in exemplary procedures200may be eliminated, without departing from the spirit and scope of the disclosure.

A communication device (child communication device) accessing a network via another communication device (relay communication device) may also need to register with the network. In some embodiments of the present disclosure, the child communication device itself may perform a registration procedure similar to the exemplary procedure200. In some other embodiments of the present disclosure, the relay communication device may perform such registration procedure on behalf of the child communication device. The procedure of performing network registration for a child communication device will be described in detail in the following text in combination with the appended drawings.

FIGS.3A-3Eillustrate exemplary procedures of performing network registration according to some embodiments of the present disclosure.FIGS.3Aand3B describe exemplary procedures for performing a registration area update.FIG.3Cdescribes a new condition for performing a registration procedure.FIGS.3D and3Edescribe exemplary procedures for performing a periodic registration update.

FIG.3Aillustrates a flow chart of an exemplary procedure300A of performing network registration for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device310A may function as the communication device110A inFIG.1, or the communication device210inFIG.2. The communication device310B may function as the communication device110B inFIG.1, or the communication device210inFIG.2.

Referring toFIG.3A, the communication device310B may be registered with a network (not shown inFIG.3A), and may receive services from the network via a base station or a relay communication device (not shown inFIG.3A) which is in the coverage of the base station. The base station may be hereinafter referred to as “the last serving cell.” The communication device310B may move out of the coverage of the base station or the relay communication device. The communication device310B may discover a new relay communication device (e.g., communication device310A), and may switch from the last serving cell to the communication device310A.

In operation321, prior to or when the communication device310B switches to the communication device310A, the communication device310B may store registration area information (e.g., tracking area) of the last serving cell at the communication device310B (e.g., in its memory).

In operation323, during or after a connection establishment procedure between the communication device310A and the communication device310B, the communication device310A may transmit registration area (e.g., tracking area) information of the serving cell of the communication device310A (hereinafter, “current serving cell”) to the communication device310B. In some embodiments of the present disclosure, the registration area information may be transmitted via an Access Stratum (AS) layer message. In some embodiments of the present disclosure, the registration area information may be broadcast in, for example, a System Information Block 1 (SIB1) message by the serving cell.

In operation325, the communication device310B may determine whether to perform a registration procedure based on the registration area information of the last serving cell and the registration area information of the current serving cell.

In some embodiments of the present disclosure, the communication device310B may determine whether the registration area information of the current serving cell matches the registration area information of the last serving cell. When the registration area information of the current serving cell does not match the registration area information of the last serving cell, the communication device310B may perform a registration procedure with the network. In some embodiments of the present disclosure, the communication device310B may further replace the registration area information of the last serving cell with that of the current serving cell. When the registration area information of the current serving cell matches the registration area information of the last serving cell, the communication device310B may not perform the registration procedure.

For example, the registration area information of the current serving cell may indicate a tracking area A identified by a TAC #1, and the registration area information of the last serving cell may indicate a tracking area B identified by a TAC #2. The communication device310B may determine whether the registration area information of the current serving cell matches the registration area information of the last serving cell by determine whether TAC #1 is the same as TAC #2. If TAC #1 is the same as (e.g., equals to) TAC #2, the communication device310B may not perform the registration procedure; and if not, the communication device310B may perform the registration procedure.

In some embodiments of the present disclosure, the registration procedure performed by the communication device310B is similar to the one described above with respect toFIG.2, except that the messages between the communication device310B and the corresponding base station are relayed by the communication device310A.

FIG.3Billustrates a flow chart of an exemplary procedure300B of performing network registration for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device311A may function as the communication device110A inFIG.1, or the communication device210inFIG.2. The communication device311B may function as the communication device110B inFIG.1, or the communication device210inFIG.2.

Referring toFIG.3B, the communication device311B may be registered with a network (not shown inFIG.3B), and may receive services from the network via a base station or a serving cell. The communication device311B may move out of the serving cell (hereinafter, “last serving cell” or “previous serving cell”). The communication device311B may discover a new relay communication device (e.g., communication device311A), and may switch from the last serving cell to the communication device311A.

In operation331, during or after a connection establishment procedure between the communication device311A and the communication device311B, the communication device311B may transmit registration information to the communication device311A. In some embodiments of the present disclosure, the registration information may be transmitted via an Access Stratum (AS) layer message. In some embodiments of the present disclosure, the registration information may include registration area (e.g., tracking area) information of the last serving cell. In some embodiments of the present disclosure, the registration information may include an identity of the communication device311B. The identity of a communication device may be a UE ID.

In operation333, the communication device311A may determine whether to perform a registration procedure for the communication device311B based on the registration information from the communication device311B.

In some embodiments of the present disclosure, the communication device311A may determine whether the registration information from the communication device311B matches the registration information of a serving cell of the communication device311A. The registration information of the serving cell of the communication device311A (hereinafter, “current serving cell”) may indicate a tracking area of the current serving cell.

When the registration area information from the communication device311B matches the registration information of the current serving cell, the communication device311A may not perform a registration procedure for the communication device311B. When the registration area information from the communication device311B does not match the registration information of the current serving cell, the communication device311A may perform a registration procedure for the communication device311B.

In some embodiments of the present disclosure, when the registration area information from the communication device311B does not match the registration information of the current serving cell, the communication device311A may transmit the registration information of the current serving cell to the communication device311B. The communication device311B may store the registration information of the current serving cell in, for example, its memory.

For example, the registration area information of the current serving cell may indicate a tracking area A identified a TAC #1, and the registration area information of the last serving cell may indicate a tracking area B identified a TAC #2. The communication device311A may determine whether the registration area information of the current serving cell matches the registration area information of the last serving cell by determine whether TAC #1 is the same as TAC #2. If TAC #1 is the same as (e.g., equals to) TAC #2, the communication device311A may not perform the registration procedure for the communication device311B; and if not, the communication device311A may perform the registration procedure for the communication device311B.

In some embodiments of the present disclosure, the registration procedure performed by the communication device311A for the communication device311B is similar to the one described above with respect toFIG.2. In particular, since the communication device311A transmits the registration request message for the communication device311B, the registration request message transmitted by the communication device311A may include the identity of the communication device311B, which is in an idle mode. In some embodiments of the present disclosure, the registration request message may further include at least one other idle child communication device of the communication device311A. In some embodiments of the present disclosure, the registration request message may be transmitted in Non-Access Stratum (NAS) signaling included in a Radio Resource Control (RRC) message.

For example, the communication device311A may have two child communication devices that are in an idle mode, for example, one is the communication device311B, and the other is communication device311C (now shown inFIG.3B). In some embodiments of the present disclosure, the communication device311A may transmit a registration request message including only the identity of the communication device311B to the network via a corresponding base station. In some other embodiments of the present disclosure, the communication device311A may transmit a registration request including the identities of both the communication device311B and the communication device311C to the network via the serving base station of the communication device311A.

FIG.3Cillustrates a flow chart of an exemplary procedure300C of performing network registration for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device312A may function as the communication device110A inFIG.1, or the communication device210inFIG.2.

Referring toFIG.3C, the communication device312A may be registered with a network (not shown inFIG.3C), and may receive services from the network via a base station or a serving cell. The communication device312A may have at least one child node. The at least one child node may communicate with the base station or the network via the communication device312A.

Under certain circumstances, the link between the communication device312A and its child nodes (e.g., communication device312B, which is not shown inFIG.3C) may fail. The number of the child nodes of the communication device312A may change from, for example, “N” to “N−1.” The definition of the link failure between a remote communication device and a relay communication device are defined in 3GPP specifications.

Under certain circumstances, a communication device (e.g., communication device312D, which is not shown inFIG.3C) may establish a link to the communication device312A, and become a new child node of the communication device312A. The number of the child nodes of the communication device312A may change from, for example, “N” to “N+1.”

In operation341, the communication device312A may determine whether is a trigger condition is met. The trigger condition may be a change in the number of child nodes of the communication device312A. In some embodiments of the present disclosure, the trigger condition may be a change in the number of child nodes of the communication device312A that are in an idle mode (idle child nodes).

If it is determined that the number of idle child nodes is changed, the communication device312A may perform, in operation343, a registration procedure for its child nodes. Otherwise, if it is determined that the number of idle child nodes is not changed, the communication device312A may not perform a registration procedure for its child nodes.

In some embodiments of the present disclosure, the registration procedure performed by the communication device312A for its child nodes is similar to the one described above with respect toFIG.2, except that the communication device312A transmits the registration request message for its child nodes, and the registration request message may include the identity of at least one idle child node of the communication device312A. In some embodiments of the present disclosure, the at least one idle child node of the communication device312A may include all idle child nodes of the communication device312A. In some embodiments of the present disclosure, the at least one idle child node of the communication device312A may include some of idle child nodes of the communication device312A.

As mentioned above, to manage the reachability of a communication device, the network may configure a communication device to periodically perform a registration procedure (i.e., “periodic registration update”). For example, the network (e.g., an AMF) may configure a communication device with a periodic registration timer during a registration procedure. A communication device may perform a periodic registration update by starting the periodic registration timer when, for example, the communication device enters into an idle mode, and performing a registration procedure in response to an expiry of the periodic registration timer. The registration procedure performed by the communication device is the same as the one described above with respect toFIG.2.

A communication device (child communication device) accessing a network via another communication device (relay communication device) may also need to periodically register with the network. In some embodiments of the present disclosure, the child communication device itself may perform a periodic registration update by periodically performing a registration procedure as described above with respect to the exemplary procedure200inFIG.2. In some other embodiments of the present disclosure, the relay communication device may perform the periodic registration update on behalf of its child communication device(s). The procedure of performing a periodic registration update for a child communication device will be described in detail in the following text in combination with the appended drawings.

FIG.3Dillustrates a flow chart of an exemplary procedure300D of performing a periodic registration update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device313A may function as the communication device110A inFIG.1, or the communication device210inFIG.2. The communication device313B may function as the communication device110B inFIG.1, or the communication device210inFIG.2.

Referring toFIG.3D, the communication device313B may be registered with a network (not shown inFIG.3D), and may receive services from the network via the communication device313A. In other words, the communication device313B is a child node of the communication device313A.

In operation351, the communication device313B may transmit timer information regarding a periodic registration timer (e.g., periodic timer A) to the communication device313A. In some embodiments of the present disclosure, in the case that the periodic timer A is running at the communication device313B, the communication device313B may stop the periodic timer A in response to transmitting the timer information.

In operation353, the communication device313A may start a periodic registration timer (e.g., periodic timer B) based on the received timer information. The communication device313A may perform a registration procedure for the communication device313B in response to an expiry of the periodic timer B. The communication device313A may restart the periodic timer B in response to the expiry of the periodic timer B.

In some embodiments of the present disclosure, the timer information may be transmitted to the communication device313A during or after a connection establishment procedure between the communication device313A and the communication device313B. For example, the timer information may be transmitted via an AS layer message.

In some embodiments of the present disclosure, the timer information may include a time interval of the periodic timer A and an amount of elapsed time of the periodic timer A. Prior to starting the periodic timer B, the communication device313A may start a timer (e.g., timer C) in response to receiving the timer information. The timer C may have a time duration equal to the time interval of the periodic timer A minus the amount of elapsed time of the periodic timer A. The communication device313A may start the periodic timer B in response to the expiry of the timer C. The periodic timer B may have a time interval equal to the time interval of the periodic timer A.

In some embodiments of the present disclosure, the registration procedure performed by the communication device313A for the communication device313B is similar to the one described above with respect toFIG.2, except that the communication device313A transmits the registration request for its child communication device (e.g., the communication device313B), and the registration request message may include registration information indicating the identity of at least one child communication device of the communication device313A, which is in an idle mode. In some embodiments of the present disclosure, the at least one idle child communication device may include only the communication device313B, which is in an idle mode. In some embodiments of the present disclosure, the at least one idle child communication device may include the communication device313B and one or more other idle child communication devices. For example, the at least one child communication device may include all idle child communication devices of the communication device313A.

In some embodiments of the present disclosure, in addition to receiving timer information from the communication device313B, the communication device313A may receive timer information from one or more other child communication devices (if any). In some embodiments, the communication device313A may receive timer information from all of its child communication devices. In some embodiments of the present disclosure, the communication device313A may receive timer information from some of its child communication devices. Each timer information from a respective child communication device may include a respective time interval, which corresponds to a respective periodic registration timer at the respective child communication device.

For example, the communication device313B may transmit the timer interval (e.g., TI #A) of the periodic timer A to the communication device313A. A communication device313C (not shown inFIG.3D) is a child communication device of the communication device313A, and may be configured with a periodic registration timer (e.g., periodic timer D) having a timer interval (e.g., TI #D). The communication device313C may transmit the TI #D to communication device313A.

After receiving the timer intervals from its child communication devices, the communication device313A may start, in operation353, the periodic timer B based on received timer intervals. In some embodiments, the communication device313A may determine a minimum value of the timer intervals of the corresponding periodic registration timers of the child communication devices. The communication device313A may set the time interval of the periodic timer B as the minimum value. For example, the communication device313A may set the time interval of the periodic timer B as the minimum value of TI #A and TI #D.

In some embodiments of the present disclosure, the communication device313A may perform, in operation353, the registration procedure for at least one child communication device that has transmitted timer information thereto (e.g., the communication device313B and communication device313C) in response to the expiry of the periodic timer B. For example, the communication device313A may perform a registration procedure similar to the one described above with respect toFIG.2, except that the registration request transmitted by the communication device313A for the at least one child communication device (e.g., the communication device313B and communication device313C) may include registration information indicating the identity of all or some of the at least one child communication device, which is in an idle mode.

FIG.3Eillustrates a flow chart of an exemplary procedure300E of performing a periodic registration update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device314A may function as the communication device110A inFIG.1, or the communication device210inFIG.2. The BS320may function as the BS120inFIG.1, or the BS220inFIG.2.

Referring toFIG.3E, the communication device314A may be registered with a network (not shown inFIG.3E), and may receive services from the network via the BS320.

In operation361, the communication device314A may receive a configuration message from the BS320. In some embodiments of the present disclosure, the configuration message may indicate a timer interval of a period timer (e.g., periodic registration timer) for at least one child communication device of the communication device314A. The configuration message may be transmitted in a broadcast message or a dedicated signaling from the BS320.

In operation363, the communication device314A may start a period timer for at least one child communication device of the communication device314A, which is in an idle mode. In some embodiments of the present disclosure, the communication device314A may start the period timer when a child communication device of the communication device314A enters into an idle mode.

In some embodiments of the present disclosure, the communication device313A may perform a registration procedure for at least one idle child communication device in response to the expiry of the period timer. For example, the communication device314A may perform a registration procedure similar to the one described above with respect toFIG.2, except that the registration request transmitted by the communication device314A for the at least one idle child communication device may include registration information indicating the identity of the at least one idle child communication device.

It should be appreciated by persons skilled in the art that some of the operations in exemplary procedures300A-300E may be eliminated, without departing from the spirit and scope of the disclosure.

A RAN-based Notification Area (RNA) may allow base station to know the rough location of a UE that is in an inactive mode (inactive UE). The RNA may include one or more cells or one or more RAN areas, and may be configured by a RAN node (e.g., a base station) to a UE using, for example, dedicated signaling. The RAN node may trigger a paging procedure for an inactive UE within the UE's RNA when the RAN wants to exchange data or control signaling with the inactive UE. Therefore, it is important for the RAN to be aware of the inactive UE moving out of the configured RNA. Thus, the UE may perform a RNA update when moving out of the configured RNA (that is, triggered by RNA change). In addition, the UE may be configured to perform a RNA update periodically (hereinafter, “periodic RNA update”).

FIG.4illustrates a flow chart of an exemplary procedure400of performing a RNA update for a communication device according to some embodiments of the present disclosure. The exemplary procedure400is applicable to the above two types of RNA update, i.e., a RNA update triggered by RNA change and a periodic RNA update, and other types of a RNA update.

Referring toFIG.4, at the beginning, communication device410may communicate with a base station (e.g., BS420′). The communication device410may perform a RNA update procedure when it moves out of the BS420′ (i.e., lasting serving base station), and may switch to a new base station (e.g., BS420). In some examples, the communication device410may function as the communication device110A or the communication device110B inFIG.1. The BS420and BS420′ may function as the BS120inFIG.1.

In operation451, the communication device410may transmit an RRC connection resume request to a new base station (e.g., the BS420). In some embodiments, the resume request may include a cause value indicating a RNA update. In some embodiments, the resume request may include the identity of the communication device410. The identity of the communication device410may be a resume ID configured by the last serving base station (e.g., the BS420′) in a RRC release message. The resume ID may include information regarding the last serving base station (e.g., the BS420′). In some embodiments, a resume ID may include an Inactive-Radio Network Temporary Identifier (I-RNTI).

In operation453, the BS420may transmit a request for acquiring UE context of the communication device410to the lasting serving base station (e.g., BS420′) of the communication device410. In some embodiments, the request for acquiring UE context may include the identity of the communication device410. In some embodiments, the request for acquiring UE context may include the cause value received from the communication device410. In operation455, the BS420′ may transmit the UE context of the communication device410to the BS420.

In operations457and459, the BS420may perform a path switch procedure for the communication device410. In operation457, the BS420may transmit a path switch request for the communication device410to the core network (e.g., AMF430). In operation459, the AMF430may transmit a path switch request response to the BS420. The path switch request response may include the identity of the communication device410.

In operation461, the BS420may transmit a RNA update acknowledge message to the communication device410. The acknowledge message may include the identity of the communication device410. In operation463, the BS420may transmit a UE context release message to the BS420′. The release message may include the identity of the communication device410.

It should be appreciated by persons skilled in the art that some of the operations in exemplary procedures400may be eliminated, without departing from the spirit and scope of the disclosure.

A communication device (child communication device) accessing a base station via another communication device (relay communication device) may also need to perform a RNA update. In some embodiments of the present disclosure, the child communication device itself may perform a RNA update procedure similar to the exemplary procedure400. In some other embodiments of the present disclosure, the relay communication device may perform the RNA update procedure on behalf of the child communication device. The procedure of performing a RNA update for a child communication device will be described in detail in the following text in combination with the appended drawings.

FIGS.5A-5Eillustrate exemplary procedures of performing a RNA update according to some embodiments of the present disclosure.FIGS.5A and5Bdescribe exemplary procedures for performing a RNA update triggered by RNA change.FIG.5Cdescribes a new condition for performing a RNA update procedure.FIGS.5D and5Edescribe exemplary procedures for performing a periodic RNA update.

FIG.5Aillustrates a flow chart of an exemplary procedure500A of performing a RNA update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device510A may function as the communication device110A inFIG.1, or the communication device410inFIG.4. The communication device510B may function as the communication device110B inFIG.1, or the communication device410inFIG.4.

Referring toFIG.5A, the communication device510B may access a base station or a serving cell via the communication device510A. The communication device510B may move out of the serving cell (hereinafter, “last serving cell” or “previous serving cell”). The communication device510B may discover a new relay communication device (e.g., communication device510A), and may switch from the last serving cell to the communication device510A.

In operation521, prior to or when the communication device510B switches to the communication device510A, the communication device510B may store RNA information of the last serving cell at the communication device510B (e.g., in its memory). The RNA information may indicate a list of cells or a list of RAN area IDs, depending on the configuration of the last serving cell. A RAN area may be identified by a RAN area ID. A RAN area ID may include a TAC, and may optionally include a RAN area code. A RAN area may cover one or more cells.

In operation523, during or after a connection establishment procedure between the communication device510A and the communication device510B, the communication device510A may transmit a message including RNA information of the serving cell of the communication device510A (hereinafter, “current serving cell”) and an ID of the current serving cell to the communication device510B. The RNA information of the current serving cell may indicate a list of cells or a list of RAN area IDs, depending on the configuration of the current serving cell. In some embodiments of the present disclosure, the message may be an Access Stratum (AS) layer message.

In operation525, the communication device510B may determine whether to perform a RNA update procedure based on the RNA information of the last serving cell stored at the communication device510B and the message received from the communication device510A.

In some embodiments of the present disclosure, the communication device510B may determine whether the ID of the current serving cell is included in the RNA information of the last serving cell. When the ID of the current serving cell is not included in the RNA information of the last serving cell, the communication device510B may perform a RNA update procedure. In some embodiments of the present disclosure, the communication device510B may further replace the stored RNA information of the last serving cell with that of the current serving cell received from the communication device510A. When the ID of the current serving cell is included in the RNA information of the last serving cell, the communication device510B may not perform a RNA update procedure.

In some embodiments of the present disclosure, the communication device510B may determine whether the RNA information of the last serving cell is the same as the RNA information of the current serving cell. When the RNA information of the last serving cell is different from that of the current serving cell, the communication device510B may replace the stored RNA information of the last serving cell with that of the current serving cell received from the communication device510A.

In some embodiments of the present disclosure, the RNA update procedure performed by the communication device510B is similar to the one described above with respect toFIG.4, except that the messages between the communication device510B and the corresponding base station are relayed by the communication device510A.

FIG.5Billustrates a flow chart of an exemplary procedure500B of performing a RNA update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device511A may function as the communication device110A inFIG.1, or the communication device410inFIG.4. The communication device511B may function as the communication device110B inFIG.1, or the communication device410inFIG.4.

Referring toFIG.5B, the communication device511B may access a base station or a serving cell via the communication device510A. The communication device511B may move out of the serving cell (hereinafter, “last serving cell” or “previous serving cell”). The communication device511B may discover a new relay communication device (e.g., communication device511A), and may switch from the last serving cell to the communication device511A.

In operation531, during or after a connection establishment procedure between the communication device511A and the communication device511B, the communication device511B may transmit a message including RNA information of the last serving cell and the identity of the communication device511B to the communication device511A. The identity of a communication device may be a resume ID (e.g., I-RNTI). In some embodiments of the present disclosure, the message may be an Access Stratum (AS) layer message.

In operation533, the communication device511A may determine whether to perform a RNA update procedure for the communication device511B based on the message (e.g., the RNA information of the last serving cell) from the communication device511B. The RNA information of the last serving cell may indicate a list of cells or a list of RAN area IDs, depending on the configuration of the last serving cell.

In some embodiments of the present disclosure, the communication device511A may determine whether the RNA information of the last serving cell from the communication device511B matches the RNA information of a serving cell of the communication device511A (hereinafter, “current serving cell”). The RNA information of the current serving cell may indicate a list of cells or a list of RAN area IDs, depending on the configuration of the current serving cell.

In some embodiments of the present disclosure, the RNA information of the last serving cell may indicate a list of cells. The communication device511A may determine whether the RNA information of the last serving cell from the communication device511B matches the RNA information of the current serving cell of the communication device511A by determining whether the list of cells include the current serving cell (e.g., the serving cell of the communication device511A). When the list of cells does not include the current serving cell, the RNA information of the last serving cell does not match the RNA information of the current serving cell; otherwise, the RNA information of the last serving cell matches the RNA information of the current serving cell.

In some embodiments of the present disclosure, the RNA information of the last serving cell may indicate a list of RAN areas. The communication device511A may determine whether the RNA information of the last serving cell from the communication device511B matches the RNA information of the current serving cell of the communication device511A by determining whether the list of RAN areas include the current serving cell (e.g., the serving cell of the communication device511A). When the list of RAN areas does not include the current serving cell, the RNA information of the last serving cell does not match the RNA information of the current serving cell; otherwise, the RNA information of the last serving cell matches the RNA information of the current serving cell.

When the RNA information of the last serving cell from the communication device511B matches the RNA information of the current serving cell of the communication device511A, the communication device511A may not perform a RNA update procedure for the communication device511B. When the RNA information of the last serving cell from the communication device511B does not match the RNA information of the current serving cell of the communication device511A, the communication device511A may perform a RNA update procedure for the communication device511B.

In some embodiments of the present disclosure, the RNA update procedure performed by the communication device511A for the communication device511B is similar to the one described above with respect toFIG.4, except that the communication device511A transmits the resume request for its child communication device (e.g., the communication device511B) to the serving base station, and the resume request may include the identity of at least one child communication device of the communication device511A, which is in an inactive mode. In some embodiments of the present disclosure, the resume request may be transmitted by a Radio Resource Control (RRC) message.

In some embodiments of the present disclosure, the at least one inactive child communication device may include only the communication device511B, which is in an inactive mode. For example, the resume request may include the resume ID (e.g., I-RNTI) of the communication device511B. In some embodiments of the present disclosure, the at least one inactive child communication device may include all or a part of the inactive child communication devices of the communication device511A. For example, the communication device511A may have two inactive child communication devices; one is the communication device511B, and the other is communication device511C (now shown inFIG.5B). The resume request may include the resume ID (e.g., I-RNTI) of the communication device511B and the resume ID (e.g., I-RNTI) of the communication device511C.

In some embodiments of the present disclosure, the communication device511A may determine, in operation533, whether the RNA information of the last serving cell from the communication device511B is different from the RNA information of the current serving cell of the communication device511A. When the RNA information of the last serving cell is different from the RNA information of the current serving cell, the communication device511A may transmit the RNA information of the current serving cell to the communication device511B. The communication device511B may store the RNA information of the current serving cell in, for example, its memory.

For example, the RNA information of the last serving cell may indicate a list of cells including cell #1 to cell #4, and the RNA information of the current serving cell may indicate a list of cells including cell #3 to cell #6. In another example, the RNA information of the last serving cell may indicate a list of cells including cell #1 to cell #2, and the RNA information of the current serving cell may indicate a list of cells including cell #3 to cell #6. In the above examples, the communication device511A may determine that the RNA information of the last serving cell is different from that of the current serving cell, and may transmit the RNA information of the current serving cell (e.g., the list of cells including cell #3 to cell #6) to the communication device511B.

FIG.5Cillustrates a flow chart of an exemplary procedure500C of performing a RNA update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device512A may function as the communication device110A inFIG.1, or the communication device410inFIG.4.

Referring toFIG.5C, the communication device512A may be registered with a network (not shown inFIG.5C), and may receive services from the network via a base station or a serving cell. The communication device512A may have at least one child node. The at least one child node may communicate with the base station or the network via the communication device512A.

Under certain circumstances, the link between the communication device512A and its child nodes (e.g., communication device512B, which is not shown inFIG.5C) may fail. The number of the child nodes of the communication device512A may change from, for example, “N” to “N−1.” The definition of the link failure between a remote communication device and a relay communication device are defined in 3GPP specifications.

Under certain circumstances, a communication device (e.g., communication device512D, which is not shown inFIG.5C) may establish a link to the communication device512A, and become a new child node of the communication device512A. The number of the child nodes of the communication device512A may change from, for example, “N” to “N+1.”

In operation541, the communication device512A may determine whether is a trigger condition is met. The trigger condition may be a change in the number of child nodes of the communication device512A. In some embodiments of the present disclosure, the trigger condition may be a change in the number of child nodes of the communication device512A that are in an inactive mode (inactive child nodes).

If it is determined that the number of inactive child nodes is changed, the communication device512A may perform, in operation543, a RNA update procedure for its child nodes. Otherwise, if it is determined that the number of inactive child nodes is not changed, the communication device512A may not perform a RNA update procedure for its child nodes.

In some embodiments of the present disclosure, the RNA update procedure performed by the communication device512A for its child nodes is similar to the one described above with respect toFIG.4, except that the communication device512A transmits the resume request for its child nodes, and the resume request may include the identity of at least one inactive child node of the communication device512A. In some embodiments of the present disclosure, the at least one inactive child node of the communication device512A may include all inactive child nodes of the communication device512A. In some embodiments of the present disclosure, the at least one inactive child node of the communication device512A may include a part of inactive child nodes of the communication device512A.

FIG.5Dillustrates a flow chart of an exemplary procedure500D of performing a periodic RNA update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device513A may function as the communication device110A inFIG.1, or the communication device410inFIG.4. The communication device513B may function as the communication device110B inFIG.1, or the communication device410inFIG.4.

Referring toFIG.5D, the communication device513B may access a base station or a serving cell via the communication device513A. In other words, the communication device513B is a child node of the communication device513A.

In operation551, the communication device513B may transmit timer information regarding a periodic RNA update timer (e.g., periodic timer E) to the communication device513A. In some embodiments of the present disclosure, in the case that the periodic timer E is running at the communication device513B, the communication device513B may stop the periodic timer E in response to transmitting the timer information.

In operation553, the communication device513A may start a periodic RNA update timer (e.g., periodic timer F) based on the received timer information. The communication device513A may perform a RNA update procedure for the communication device513B in response to an expiry of the periodic timer F. The communication device513B may restart the periodic timer F in response to the expiry of the periodic timer F.

In some embodiments of the present disclosure, the timer information may be transmitted to the communication device513A during or after a connection establishment procedure between the communication device513A and the communication device513B. For example, the timer information may be transmitted via an AS layer message.

In some embodiments of the present disclosure, the timer information may include a time interval of the periodic timer E and an amount of elapsed time of the periodic timer E. Prior to starting the periodic timer F, the communication device513A may start a timer (e.g., timer G) in response to receiving the timer information. The timer G may have a time duration equal to the time interval of the periodic timer E minus the amount of elapsed time of the periodic timer E. The communication device513A may start the periodic timer F in response to the expiry of the timer G. The periodic timer F may have a time interval equal to the time interval of the periodic timer E.

In some embodiments of the present disclosure, the RNA update procedure performed by the communication device513A for the communication device513B is similar to the one described above with respect toFIG.4, except that the communication device513A transmits the resume request for its child communication device (e.g., the communication device513B), and the resume request may include the identity of at least one child communication device of the communication device513A, which is in an inactive mode. In some embodiments of the present disclosure, the at least one child communication device may include all of the inactive child communication devices of the communication device513A. In some embodiments of the present disclosure, the at least one child communication device may include some of the inactive child communication devices of the communication device513A.

In some embodiments of the present disclosure, in addition to receiving timer information from the communication device513B, the communication device513A may receive timer information from one or more other child communication devices (if any). In some embodiments, the communication device513A may receive timer information from all of its child communication devices. In some embodiments of the present disclosure, the communication device513A may receive timer information from some of its child communication devices. Each timer information from a respective child communication device may include a respective time interval, which corresponds to a respective periodic RNA update timer at the respective child communication device.

For example, the communication device513B may transmit the timer interval (e.g., TI #E) of the periodic timer E to the communication device513A. A communication device513C (not shown inFIG.5D) is a child communication device of the communication device513A, and may be configured with a periodic RNA update timer (e.g., periodic timer H) having a timer interval (e.g., TI #H). The communication device513C may transmit the TI #H to communication device513A.

After receiving the timer intervals from its child communication devices, the communication device513A may start, in operation553, the periodic timer F based on the received timer intervals. In some embodiments, the communication device513A may determine a minimum value of the timer intervals of the corresponding periodic RNA update timers of the child communication devices. The communication device513A may set the time interval of the periodic timer F as the minimum value. For example, the communication device513A may set the time interval of the periodic timer F as the minimum value of TI #E and TI #H.

In some embodiments of the present disclosure, the communication device513A may perform, in operation553, a RNA update procedure for at least one child communication device that has transmitted timer information thereto (e.g., the communication device513B and communication device513C) in response to the expiry of the periodic timer F. For example, the communication device513A may perform a RNA update procedure similar to the one described above with respect toFIG.4, except that the resume request transmitted by the communication device513A for the at least one child communication device (e.g., the communication device513B and communication device513C) may include the identity of the at least one child communication device, which is in an inactive mode. In some embodiments of the present disclosure, the at least one inactive child communication device may include all of the inactive child communication devices of the communication device513A. In some embodiments of the present disclosure, the at least one child communication device may include some of the inactive child communication devices of the communication device513A.

FIG.5Eillustrates a flow chart of an exemplary procedure500E of performing a periodic RNA update for a communication device according to some embodiments of the present disclosure.

In some examples, the communication device514A may function as the communication device110A inFIG.1, or the communication device410inFIG.4. The BS520may function as the BS120inFIG.1, or the BS420inFIG.4.

Referring toFIG.5E, the communication device514A may be registered with a network (not shown inFIG.5E), and may receive services from the network via the BS520.

In operation561, the communication device514A may receive a configuration message from the BS520. In some embodiments of the present disclosure, the configuration message may indicate a timer interval of a period timer (e.g., periodic RNA update timer) for at least one child communication device of the communication device514A. The configuration message may be transmitted in a broadcast message or a dedicated signaling from the BS520.

In operation563, the communication device514A may start a period timer for at least one inactive child communication device of the communication device514A. In some embodiments of the present disclosure, the communication device514A may start the period timer when a child communication device of the communication device514A moving out of the RNA configured for the child communication device.

In some embodiments of the present disclosure, the communication device514A may perform a RNA update procedure for at least one inactive child communication device in response to the expiry of the period timer. For example, the communication device513A may perform a RNA update procedure similar to the one described above with respect toFIG.4, except that the resume request transmitted by the communication device514A for the at least one inactive child communication device may include the identity of the at least one inactive child communication device. In some embodiments of the present disclosure, the at least one inactive child communication device may include all of the inactive child communication devices of the communication device514A. In some embodiments of the present disclosure, the at least one child communication device may include some of the inactive child communication devices of the communication device514A.

It should be appreciated by persons skilled in the art that some of the operations in exemplary procedures500A-500E may be eliminated, without departing from the spirit and scope of the disclosure.

FIG.6illustrates an example block diagram of an apparatus600according to some embodiments of the present disclosure.

As shown inFIG.6, the apparatus600may include at least one non-transitory computer-readable medium (not illustrated inFIG.6), a receiving circuitry602, a transmitting circuitry604, and a processor606coupled to the non-transitory computer-readable medium (not illustrated inFIG.6), the receiving circuitry602and the transmitting circuitry604. The apparatus600may be a communication device (e.g., a UE).

Although in this figure, elements such as processor606, transmitting circuitry604, and receiving circuitry602are described in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present disclosure, the receiving circuitry602and the transmitting circuitry604are combined into a single device, such as a transceiver. In certain embodiments of the present disclosure, the apparatus600may further include an input device, a memory, and/or other components.

In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause a processor to implement the method with respect to the communication device as described above. For example, the computer-executable instructions, when executed, cause the processor606to interact with receiving circuitry602and transmitting circuitry604, so as to perform the steps with respect to the communication devices or UEs depicted inFIGS.1,2,3A-3E,4, and5A-5E.

In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause a processor to implement the method with respect to the base station as described above. For example, the computer-executable instructions, when executed, cause the processor606to interact with receiving circuitry602and transmitting circuitry604, so as to perform the steps with respect to the base stations depicted inFIGS.1,2,3A-3E,4, and5A-5E.

In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause a processor to implement the method with respect to the network entity as described above. For example, the computer-executable instructions, when executed, cause the processor606to interact with receiving circuitry602and transmitting circuitry604, so as to perform the steps with respect to the network entity (e.g., AMF) depicted inFIGS.1,2,3A-3E,4, and5A-5E.

Those having ordinary skill in the art would understand that the steps of a method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the steps of a method may reside as one or any combination or set of codes and/or instructions on a non-transitory computer-readable medium, which may be incorporated into a computer program product.

While this disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for the operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the disclosure by simply employing the elements of the independent claims. Accordingly, embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure.

In this document, the terms “includes”, “including”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a”, “an”, or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term “another” is defined as at least a second or more. The term “having” and the like, as used herein, are defined as “including”.