Patent ID: 12256452

DETAILED DESCRIPTION OF THE DRAWINGS

Generally speaking, the techniques of this disclosure allow a user device (UE) to successfully communicate all segments of a segmented RRC message to one or more base stations of a RAN, even in the event of radio link failure, and without retransmitting segments unnecessarily. In this disclosure, any reference to different actions (e.g., receiving, transmitting, etc.) being performed by a “RAN” may indicate that the actions are all performed by a single base station of the RAN, or that the actions are performed by different base stations of the RAN, depending on the implementation and/or scenario. For example, a series of communications between a user device and a RAN may involve two different base stations if a handover occurs during the course of those communications. Also in this disclosure, and depending on the implementation and/or scenario, “failure” of a radio link may specifically refer to Radio Link Failure or “RLF” (e.g., as defined in the 5G standard), or may more generally refer to the user device and RAN being unable to communicate via the radio link for any reason.

These techniques are discussed below with example reference to a 5G radio access (“NR”) network and a 5G core network (5GC). However, the techniques of this disclosure can apply to other radio access and/or core network technologies.

Referring first toFIG.1, a UE102can operate in an example wireless communication network100. The wireless communication network100includes base stations104-1and104-2, associated with respective cells106-1and106-2. As used herein, “RAN104” refers to a radio access network that includes at least base stations104-1and104-2. WhileFIG.1depicts each of base stations104-1and104-2as serving only one cell, it is understood that the base station104-1and/or the base station104-2may also cover one or more additional cells not shown inFIG.1. In general, the wireless communication network100can include any number of base stations, and each of the base stations can cover one, two, three, or any other suitable number of cells.

The base stations104-1and104-2may each operate as a 5G Node B (gNB), for example, and are referred to as such the example messaging diagrams ofFIGS.2-9(discussed below). As seen inFIG.1, the base station104-1and the base station104-2are both connected to a 5GC110, which is in turn connected to the Internet112. In various alternative implementations and/or scenarios, the wireless communication network100does not include the base station104-2and/or the cell106-2, or the base station104-2is a next-generation evolved Node B (ng-eNB) and the cell106-2is an Evolved Universal Terrestrial Radio Access (EUTRA) cell, etc.

The UE102can support an NR air interface, and exchange messages with the base station104-1when operating in the cell106-1or the base station104-2when operating in the cell106-2. In other implementations, the UE102also can support a EUTRA air interface, and exchange messages with the base station104-1over 5G NR when operating in the cell106-1, and with the base station104-2over EUTRA when operating in the cell106-2. As discussed below, the UE102can be any suitable device capable of wireless communications.

The UE102is equipped with processing hardware120, which can include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable memory storing instructions that the one or more general-purpose processors can execute. Additionally or alternatively, the processing hardware120can include special-purpose processing units, such as a wireless communication chipset, for example. The processing hardware120includes an RRC controller122. The RRC controller122is responsible for inbound messaging, outbound messaging, and internal procedures at the corresponding layer of a wireless communication protocol stack130, discussed further below. While not shown inFIG.1, the processing hardware120may also include a controller for each of a number of other layers, such as a mobility management (MM) controller and/or a packet data convergence protocol (PDCP) controller. For example, a PDCP controller of UE102may generate PDUs that package/contain RRC PDUs (containing RRC messages) generated by RRC controller122.

The RRC controller122can be implemented using any suitable combination of hardware, software, and/or firmware. In one example implementation, the RRC controller122is a set of instructions that defines respective components of the operating system of the UE102, and one or more CPUs of the processing hardware120execute these instructions to perform the respective RRC functions. In another implementation, the RRC controller122is implemented using firmware as a part of a wireless communication chipset.

The protocol stack130, illustrated in a simplified manner inFIG.1, includes, among other possible layers, a physical layer132(commonly abbreviated as the PHY layer), a medium access control layer134(commonly abbreviated as the MAC layer), a radio link control (RLC) layer136, a PDCP layer138, and an RRC layer140, as parts of an access stratum142. A non-access stratum (NAS)150of the protocol stack130includes, among other possible layers, one or more MM layers152for handling registration, attachment, or tracking area update procedures. As further illustrated inFIG.1, the protocol stack130also supports higher-layer protocols154for various services and applications. For example, the higher-layer protocols154may include Internet Protocol (IP), Transmission Control Protocol and User Datagram Protocol (UDP).

The RRC layer140packages and interprets RRC PDUs, which may contain any of various types of RRC messages associated with different RRC procedures (e.g., connection establishment or reestablishment procedures, a UE capability transfer procedure, a measurement reporting procedure, etc.). The various layers132,134,136,138,140,141,152and154may be ordered as shown inFIG.1. It is understood, however, that in some implementations and/or situations, one or more of the depicted layers may operate in a manner that does not strictly conform to the ordering shown inFIG.1.

On the UE102side, the RRC layer140(i.e., RRC controller122) can divide one or more types of RRC messages into multiple segments, and transmit the segments sequentially. In some implementations, the RRC controller122accomplishes this by including a particular RRC message in an RRC PDU, and then segmenting the RRC PDU such that each RRC PDU segment includes a corresponding RRC message segment. In this disclosure, reference to the transmission or reception of an RRC message segment may indicate (in some implementations) that the RRC message segment is transmitted or received, respectively, within a segment of an RRC PDU. As one example, if the UE102receives a UECapabilityEnquiry message from the base station104-1, the RRC controller122may respond by generating a UECapabilityInformation message, packaging the UECapabilityInformation message in an RRC PDU, dividing the RRC PDU into multiple segments, and then causing the UE102to sequentially transmit the RRC PDU segments to the base station104-1.

The base station104-1is equipped with processing hardware160, which can include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable memory storing instructions that the one or more general-purpose processors can execute. Additionally or alternatively, the processing hardware160can include special-purpose processing units, such as a wireless communication chipset, for example. Similar to the processing hardware120of UE102, the processing hardware160includes an RRC controller162. While the RRC controller122of the UE102implements functionality of the RRC layer140on the user device102side, however, the RRC controller162of the base station104-1implements functionality of the RRC layer140on the base station104-1side. As just one example, the RRC controller122may generate a measurement report message and cause the UE102to transmit the measurement report message to the base station104-1, while the RRC controller162may interpret the measurement report message when received at the base station104-1. While not shown inFIG.1, the processing hardware160may also include a controller for each of a number of other layers, such as an MM and/or PDCP controller.

The RRC controller162can be implemented using any suitable combination of hardware, software, and/or firmware. In one example implementation, the RRC controller162is a set of instructions that defines respective components of the operating system of the base station104-1, and one or more CPUs of the processing hardware160execute these instructions to perform the respective RRC functions. In another implementation, the RRC controller162is implemented using firmware as a part of a wireless communication chipset. In some implementations, the base station104-2includes processing hardware similar to the processing hardware160of the base station104-1. In other implementations, the base station104-2may be co-located with the base station104-1and share some of the processing hardware160of the base station104-1.

On the base station104-1side, the RRC layer140(i.e., RRC controller162) can process one or more types of RRC messages received as multiple, sequential segments. As one example, if the base station104-1receives a sequence of segments of a UECapabilityInformation message from the UE102(e.g., within a sequence of RRC PDU segments), the RRC controller162can successfully interpret the segmented message (i.e., determine the capabilities of the UE102as indicated in the entire UECapabilityInformation message).

For simplicity,FIG.1does not depict various components of the UE102and the base stations104-1,104-2. In addition to the layer-specific controllers mentioned above, for example, the UE102and the base stations104-1,104-2include respective transceivers, which comprise various hardware, firmware, and software components that are configured to transmit and receive wireless signals according to the NR air interface. The processing hardware120and the processing hardware160(and similar processing hardware in the base station104-2) can send commands and exchange information with the respective transceivers as needed to perform various connection establishment procedures, perform various RRC or MM procedures, or communicate with other network elements, etc.

Example message sequences and methods that the UE102, base station104-1, and/or base station104-2can implement and execute, alone or in combination with other components of the network100(e.g., 5GC110), will now be discussed with reference toFIGS.2-9. The UE102and/or base stations104-1,104-2can implement at least some of the acts described below in software, firmware, hardware, or any suitable combination of software, firmware, and hardware. AlthoughFIGS.2-9are discussed below with reference to the components depicted inFIG.1and a 5G system, in general any suitable components or wireless communication network may be used.

Referring first toFIG.2, a messaging diagram200depicts example messages that may be exchanged between the UE102and the RAN104ofFIG.1, and associated operations, according to one implementation and scenario. In the messaging diagram200, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, the operations shown for the RAN104may be performed by (or triggered by) the RRC controller162of the base station104-1, or a similar RRC controller of the base station104-2.

At the start of the messaging diagram200, the UE102and the RAN104have already established an RRC connection. As seen inFIG.2, the RAN104determines202to initiate a particular RRC procedure (“RRC Procedure A”), and then transmits204an RRC message (“RRC Message A”) to the UE102. RRC Procedure A may be a UE capability transfer procedure as defined in 3GPP TS 38.331 v15.5.1, and RRC Message A may be a UECapabilityEnquiry message, for example.

In response to receiving and processing RRC Message A, the UE102generates210all N segments of an RRC PDU containing an RRC response message (“RRC Response Message A”), where N is an integer greater than one (e.g., two, four, 10, 16, etc.). If RRC Procedure A is a UE capability transfer procedure, for example, then RRC Response Message A may be a UECapabilityInformation message that specifies various capabilities of the UE102(e.g., radio access technologies supported by the UE102, etc.). As one example, generating210the N segments may include generating the RRC Response Message A, including the RRC Response Message A in an RRC PDU, and then dividing the RRC PDU into the N segments.

The UE102then sequentially transmits (212-1through212-M) the first M of the N segments to the RAN104, where M is an integer greater than zero and less than N. In other implementations, the UE102does not generate210all N segments before transmitting212-1the first segment. For example, the UE102may instead generate210each segment just prior to transmitting212that segment, such that the generating210and transmitting212operations are interleaved.

As indicated inFIG.2(using the symbol “X”), the radio link between the UE102and the RAN104fails before the RAN104receives the M-th segment. In this disclosure, reference to a device, component, etc., failing to receive a message or segment may mean that the device, component, etc. fails to receive any part of the message or segment, or receives only a portion of the message or segment.

For example, the radio link may suffer a large and sudden degradation in signal quality. At some point shortly after the failure of the radio link, the UE102detects220the failure (e.g., during or shortly after transmission of the M-th segment). For example, the UE102may periodically measure one or more radio link quality metrics (e.g., signal to noise ratio (SNR), signal to interference-plus-noise ratio (SINR), block, bit or packet error rate, and/or other suitable metrics), and determine from those measurements that the radio link quality has degraded past some threshold value. However, the UE102may be unaware of whether the RAN104successfully received the M-th segment, and possibly unaware of whether the RAN104successfully received one or more additional segments prior to the M-th segment. For example, the difference between the time of the radio link failure and the time that the UE102detects the failure may be great enough that the UE102transmits several additional segments, which the RAN104cannot receive due to the failure.

Thus, the UE102knows how many segments the UE102has transmitted to the RAN104, but does not know how many segments the RAN104successfully received. One option, reflected inFIG.2(as well asFIGS.3-7), is for the UE102to restart transmission of the entire RRC PDU (i.e., all N segments). Another option is for the RAN104to provide feedback to the UE102, to inform the UE102of which segments the RAN104has successfully received. This latter option, which allows the UE102to avoid transmitting segments that the RAN104has already received, is reflected inFIGS.8and9(discussed below).

In response to the failure, the UE102and the RAN104perform230an RRC connection reestablishment procedure. After the UE102and RAN104reestablish the RRC connection, the RAN104determines260to initiate the same RRC Procedure A, and therefore transmits262another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102.

In response to receiving and processing RRC Message A, the UE102sequentially transmits (264-1through264-N) all N segments of the RRC Response Message A to the RAN104. That is, the UE102re-transmits (264-1through264-M) the first M segments sequentially, and then transmits (264-(M+1) through264-N) the remaining segments M+1 through N sequentially, thereby increasing the probability that the RAN104successfully receives all of the segments. After the RAN104receives all segments, the RAN104can assemble all of the segments into the complete RRC PDU.

If, in an alternative scenario, the RAN104does not determine260to initiate RRC Procedure A and transmit262another RRC Message A, or if the UE102does not successfully receive that RRC Message A, the UE102may not transmit any segments, and RRC Procedure A may fail or be further delayed.

In some implementations and/or scenarios, all operations of the RAN104shown inFIG.2are performed by the base station104-1. In other implementations and/or scenarios, however, the UE102connects to a new base station in response to the radio link failure. In such an implementation/scenario, all operations of the RAN104shown inFIG.2that occur prior to the RRC connection reestablishment procedure are performed by the base station104-1, while those that occur after the RRC connection reestablishment procedure (and at least some operations of the RRC connection reestablishment procedure itself) are performed by the base station104-2.

One of these latter implementations/scenarios is shown in the messaging diagram300ofFIGS.3A and3B. In the messaging diagram300, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, with the possible exception of the communications between the base stations104-1and104-2, the operations shown for the base station104-1may be performed by (or triggered by) the RRC controller162, and the operations shown for the base station104-2may be performed by (or triggered by) an RRC controller of the base station104-2that is similar to the RRC controller162.

At the start of the messaging diagram300, the UE102and the base station104-1have already established an RRC connection. As seen inFIG.3A, the base station104-1determines302to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits304RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates310all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (312-1through312-M) the first M segments of the N segments to the base station104-1. The generating310and transmitting312operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the base station104-1to fail to successfully receive at least the M-th segment. That is, the base station104-1receives only the first L segments, where L is an integer greater than zero and less than M. The UE102detects320the failure (e.g., as discussed above with reference toFIG.2) and, in response, determines332to initiate an RRC connection reestablishment procedure with a new base station (i.e., the base station104-2). The UE102then transmits334an RRCReestablishmentRequest message to the base station104-2.

If the base station104-2does not have context information for the UE102(e.g., the “UE Context” as defined by the 5G specification) when receiving the RRCReestablishmentRequest message from the UE102, the base station104-2transmits336a RETRIEVE UE CONTEXT REQUEST message to the base station104-1, and the base station104-1responds by transmitting338to the base station104-2the context information for the UE102in a RETRIEVE UE CONTEXT RESPONSE message. In some implementations, the base station104-1does not include the successfully received segments of the RRC PDU (i.e., the first L segments) in the RETRIEVE UE CONTEXT RESPONSE message, or in any other message that the base station104-1transmits to the base station104-2.

In other scenarios, where the base station104-2already has the context information for the UE102when receiving the RRCReestablishmentRequest from the UE102, the base station104-2does not transmit336the RETRIEVE UE CONTEXT REQUEST message to the base station104-1, and the base station104-1does not transmit338the RETRIEVE UE CONTEXT RESPONSE.FIGS.5A and5B, discussed below, reflect a scenario in which the base station104-2cannot retrieve the context information for the UE102.

Referring now toFIG.3B, the base station104-2transmits340an RRCReestablishment message to the UE102, and the UE102responds by transmitting342an RRCReestablishmentComplete message to the base station104-2. Thereafter, the base station104-2determines360to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits362another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In response to RRC Message A, the UE102sequentially transmits (364-1through364-N) all N segments of RRC Response Message A (e.g., the UECapabilityInformation message) to the base station104-2. Thus, despite the radio link failure, and despite the base station104-1not forwarding the successfully received segments (e.g., the first L segments) to the base station104-2, the base station104-2can receive all segments and assemble the complete RRC PDU containing RRC Response Message A.

FIGS.4A and4Bdepict an example messaging diagram400that corresponds to a different implementation and/or scenario. In particular, and as discussed further below, the messaging diagram400may reflect a scenario in which the RAN104cannot respond to an RRCReestablishmentRequest message from the UE102with an RRCReestablishment message. The messaging diagram400may reflect the same implementation of the wireless communication network100as the messaging diagrams200and/or300, for example, but in a different scenario (e.g., where the RAN104cannot retrieve context information for the UE102and thus cannot reestablish the connection with the UE102). In the messaging diagram400, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, the operations shown for the RAN104may be performed by (or triggered by) the RRC controller162of the base station104-1, or a similar RRC controller of the base station104-2.

At the start of the messaging diagram400, the UE102and the RAN104have already established an RRC connection. As seen inFIG.4A, the RAN104determines402to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits404RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates410all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (412-1through412-M) the first M segments of the N segments to the RAN104. The generating410and transmitting412operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the RAN104to fail to successfully receive the M-th segment (i.e., L=M−1). The UE102detects420the failure (e.g., as discussed above with reference toFIG.2) and, in response, determines432to initiate an RRC connection reestablishment procedure with the RAN104. The UE102then transmits434an RRCReestablishmentRequest message to the RAN104.

As noted above, in the scenario ofFIGS.4A and4B, the RAN104cannot respond to the RRCReestablishmentRequest message from the UE102with a RRCReestablishment message. For example, the RAN104may fail to retrieve context information for the UE102, or may be unable to transmit the RRCReestablishment message for some other reason. Therefore, the RAN104instead transmits446an RRCSetup message to the UE102, and the UE102responds by transmitting448an RRCSetupComplete message to the RAN104. Thereafter, the RAN104transmits450a SecurityModeCommand message to the UE102(e.g., to activate integrity protection, encryption, and/or other security schemes for communications between the RAN104and the UE102), and the UE102responds by transmitting452a SecurityModeComplete message to the RAN104.

Referring now toFIG.4B, the RAN104then determines460to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits462another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In response to RRC Message A, the UE102sequentially transmits (464-1through464-N) all N segments of RRC Response Message A (e.g., the UECapabilityInformation message) to the RAN104. Thus, despite the radio link failure, the RAN104can receive all segments and assemble the complete RRC PDU containing RRC Response Message A.

In some implementations and/or scenarios, all operations of the RAN104shown inFIGS.4A and4Bare performed by the base station104-1. In other implementations and/or scenarios, however, the UE102connects to a new base station in response to the radio link failure. In such an implementation/scenario, all operations of the RAN104shown inFIGS.4A and4Bthat occur prior to the radio link failure are performed by the base station104-1, while those that occur after the radio link failure are performed by the base station104-2. As will be seen in the discussion ofFIGS.5A and5B, however, other post-failure operations of the RAN104(not shown inFIGS.4A and4B) may be performed by the base station104-1.

One implementation/scenario in which the UE102connects to a new base station in response to the radio link failure is shown in the messaging diagram500ofFIGS.5A and5B. In the messaging diagram500, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, with the possible exception of the communications between the base stations104-1and104-2, the operations shown for the base station104-1may be performed by (or triggered by) the RRC controller162, and the operations shown for the base station104-2may be performed by (or triggered by) an RRC controller of the base station104-2that is similar to the RRC controller162.

At the start of the messaging diagram500, the UE102and the base station104-1have already established an RRC connection. As seen inFIG.5A, the base station104-1determines502to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits504RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates510all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (512-1through512-M) the first M segments of the N segments to the base station104-1. The generating510and transmitting512operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the base station104-1to fail to successfully receive the M-th segment (i.e., L=M−1). The UE102detects520the failure (e.g., as discussed above with reference toFIG.2) and, in response, determines532to initiate an RRC connection reestablishment procedure with a new base station (i.e., the base station104-2). The UE102then transmits534an RRCReestablishmentRequest message to the base station104-2.

If the base station104-2does not have context information for the UE102(e.g., the “UE Context” as defined by the 5G specification) when receiving the RRCReestablishmentRequest message from the UE102, the base station104-2transmits536a RETRIEVE UE CONTEXT REQUEST message to the base station104-1. In the example scenario ofFIGS.5A and5B, however, the base station104-1cannot retrieve context information for the UE102, and therefore transmits544a RETRIEVE UE CONTEXT FAILURE message to the base station104-2. In some implementations, the base station104-1does not include the successfully received segments of the RRC PDU (i.e., the first L segments) in the RETRIEVE UE CONTEXT FAILURE message, or in any other message that the base station104-1transmits to the base station104-2.

Referring now toFIG.5B, in response to the RETRIEVE UE CONTEXT FAILURE message, the base station104-2transmits546an RRCSetup message to the UE102, and the UE102responds by transmitting548an RRCSetupComplete message to the base station104-2. Thereafter, the base station104-2transmits550a SecurityModeCommand message to the UE102(e.g., to activate integrity protection, encryption, and/or other security schemes for communications between the base station104-2and the UE102), and the UE102responds by transmitting552a SecurityModeComplete message to the base station104-2. In an alternative implementation, if the base station104-2does not have the context information for the UE102at the time the base station104-2receives the RRCReestablishmentRequest message from the UE102, the base station104-2instead transmits546the RRCSetup message to the UE102earlier (e.g., before and/or instead of transmitting536the RETRIEVE UE CONTEXT REQUEST message to the base station104-1).

Next, the base station104-2determines560to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits562another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In response to RRC Message A, the UE102sequentially transmits (564-1through564-N) all N segments of RRC Response Message A (e.g., the UECapabilityInformation message) to the base station104-2. Thus, despite the radio link failure, and despite not receiving any segments from the base station104-1, the base station104-2can receive all segments and assemble the complete RRC PDU containing RRC Response Message A.

FIGS.6A and6Bdepict an example messaging diagram600that corresponds to yet another implementation and/or scenario. In particular, and as discussed further below, the messaging diagram600may reflect an implementation and/or scenario in which, after radio link failure, the UE102determines to initiate an RRC connection establishment procedure rather than an RRC connection reestablishment procedure. The messaging diagram600may reflect the same implementation of the wireless communication network100as the messaging diagrams200,300,400and/or500, for example, but in a different scenario (e.g., where certain conditions cause the UE102to decide to establish a new RRC connection). In the messaging diagram600, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, the operations shown for the RAN104may be performed by (or triggered by) the RRC controller162of the base station104-1, or a similar RRC controller of the base station104-2.

At the start of the messaging diagram600, the UE102and the RAN104have already established an RRC connection. As seen inFIG.6A, the RAN104determines602to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits604RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates610all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (612-1through612-M) the first M segments of the N segments to the RAN104. The generating610and transmitting612operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the RAN104to fail to successfully receive the M-th segment (i.e., L=M−1). The UE102detects620the failure (e.g., as discussed above with reference toFIG.2) and, in response, determines632to initiate an RRC connection establishment procedure with the RAN104.

Thereafter, the UE102transmits645an RRCSetupRequest message to the RAN104. In response, the RAN104transmits646an RRCSetup message to the UE102, and the UE102responds to the RRCSetup message by transmitting648an RRCSetupComplete message to the RAN104. Thereafter, the RAN104transmits650a SecurityModeCommand message to the UE102(e.g., to activate integrity protection, encryption, and/or other security schemes for communications between the RAN104and the UE102), and the UE102responds by transmitting652a SecurityModeComplete message to the RAN104.

Referring now toFIG.6B, the RAN104then determines660to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits662another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In response to RRC Message A, the UE102sequentially transmits (664-1through664-N) all N segments of RRC Response Message A (e.g., the UECapabilityInformation message) to the RAN104. Thus, despite the radio link failure, the RAN104can receive all segments and assemble the complete RRC PDU containing RRC Response Message A.

In some implementations and/or scenarios, all operations of the RAN104shown inFIGS.6A and6Bare performed by the base station104-1. In other implementations and/or scenarios, however, the UE102connects to a new base station in response to the radio link failure. In such an implementation/scenario, all operations of the RAN104shown inFIGS.6A and6Bthat occur prior to the radio link failure are performed by the base station104-1, while those that occur after the radio link failure are performed by the base station104-2. As will be seen in the discussion ofFIGS.7A and7B, however, other post-failure operations of the RAN104(not shown inFIGS.6A and6B) may be performed by the base station104-1.

One implementation/scenario in which the UE102connects to a new base station in response to the radio link failure is shown in the messaging diagram700ofFIGS.7A and7B. In the messaging diagram700, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, the operations shown for the base station104-1may be performed by (or triggered by) the RRC controller162, and the operations shown for the base station104-2may be performed by (or triggered by) an RRC controller of the base station104-2that is similar to the RRC controller162.

At the start of the messaging diagram700, the UE102and the base station104-1have already established an RRC connection. As seen inFIG.7A, the base station104-1determines702to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits704RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates710all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (712-1through712-M) the first M segments of the N segments to the base station104-1. The generating710and transmitting712operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the base station104-1to fail to successfully receive the M-th segment (i.e., L=M−1). The UE102detects720the failure (e.g., as discussed above with reference toFIG.2) and, in response, determines732to initiate an RRC connection establishment procedure with a new base station (i.e., the base station104-2). The UE102then transmits745an RRCSetupRequest message to the base station104-2, and the base station104-2responds by transmitting746an RRCSetup message to the UE102.

The UE102responds to the RRCSetup message by transmitting748an RRCSetupComplete message to the base station104-2, after which the base station104-2transmits750a SecurityModeCommand message to the UE102(e.g., to activate integrity protection, encryption, and/or other security schemes for communications between the base station104-2and the UE102). Referring now toFIG.7B, the UE102responds to the SecurityModeCommand message by transmitting752a SecurityModeComplete message to the base station104-2.

Next, the base station104-2determines760to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits762another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In response to RRC Message A, the UE102sequentially transmits (764-1through764-N) all N segments of RRC Response Message A (e.g., the UECapabilityInformation message) to the base station104-2. Thus, despite the radio link failure, and despite not receiving any segments from the base station104-1, the base station104-2can receive all segments and assemble the complete RRC PDU containing RRC Response Message A.

FIGS.8and9reflect a different implementation thanFIGS.2through7. In particular,FIGS.8and9reflect an implementation in which the UE102does not re-transmit every one of the first M segments of RRC Message A to the RAN104, thereby decreasing the amount of required messaging, but without causing segments to be lost (as will become clear from the following discussion).

Referring first toFIG.8, a messaging diagram800depicts example messages that may be exchanged between the UE102and the RAN104ofFIG.1, and associated operations, according to one implementation and scenario. In the messaging diagram800, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, the operations shown for the RAN104may be performed by (or triggered by) the RRC controller162of the base station104-1, or a similar RRC controller of the base station104-2.

At the start of the messaging diagram800, the UE102and the RAN104have already established an RRC connection. As seen inFIG.8, the RAN104determines802to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits804RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates810all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (812-1through812-M) the first M segments of the N segments to the RAN104. The generating810and transmitting812operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the RAN104to fail to successfully receive at least the M-th segment. That is, the RAN104successfully receives only the first L segments, where 0<L<M≤N. The UE102detects820the failure (e.g., as discussed above with reference toFIG.2), but does not know how many segments the RAN104successfully received prior to the failure (i.e., does not know the value of L).

In response to the failure, the UE102and the RAN104perform830an RRC connection reestablishment procedure. After the UE102and RAN104reestablish the RRC connection, the RAN104determines860to initiate the same RRC Procedure A, and therefore transmits862another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In this RRC Message A, however, the RAN104includes a request for the (L+1)-th segment of the RRC PDU (i.e., the (L+1)-th segment of RRC Response Message A). The request may take any suitable form that can convey to the UE102that the RAN104still needs the (L+1)-th through N-th segments. For example, the request may include a field with a value equal to L+1 (representing the next segment that the RAN104needs in the sequence of segments), a field with a value equal to L (indicating the last segment that the RAN104successfully received), a field with a value equal to N−L (indicating the number of segments at the end of the RRC PDU that the RAN104still needs), and so on.

In response to receiving and processing this RRC Message A, including the request for the L-th segment, the UE102sequentially transmits (864-(L+1) through864-N) the (L+1)-th through N-th segments of the RRC Response Message A to the RAN104. Thus, despite the radio link failure, and despite the UE102not re-transmitting at least some of the first M segments, the RAN104can successfully receive all N segments, and assemble all N segments into the complete RRC PDU.

In some implementations and/or scenarios, all operations of the RAN104shown inFIG.8are performed by the base station104-1. In other implementations and/or scenarios, however, the UE102connects to a new base station in response to the radio link failure. In such an implementation/scenario, all operations of the RAN104shown inFIG.8that occur prior to the RRC connection reestablishment procedure are performed by the base station104-1, while those that occur after the RRC connection reestablishment procedure (and at least some operations of the RRC connection reestablishment procedure itself) are performed by the base station104-2.

One of these latter implementations/scenarios is shown in the messaging diagram900ofFIGS.9A and9B. In the messaging diagram900, all operations shown for the UE102may be performed by (or triggered by, e.g., in the case of message transmission) the RRC controller122of the UE102. Similarly, with the possible exception of the communications between the base stations104-1and104-2, the operations shown for the base station104-1may be performed by (or triggered by) the RRC controller162, and the operations shown for the base station104-2may be performed by (or triggered by) an RRC controller of the base station104-2that is similar to the RRC controller162.

At the start of the messaging diagram900, the UE102and the base station104-1have already established an RRC connection. As seen inFIG.9A, the base station104-1determines902to initiate RRC Procedure A (e.g., a UE capability transfer procedure), and then transmits904RRC Message A (e.g., a UECapabilityEnquiry message) to the UE102. In response, the UE102generates910all N segments of the RRC PDU containing N respective segments of RRC Response Message A, and sequentially transmits (912-1through912-M) the first M segments of the N segments to the base station104-1. The generating910and transmitting912operations may occur during two distinct time periods or in an interleaved manner (e.g., as discussed above for the generating210and transmitting212operations ofFIG.2). In the depicted scenario, a radio link failure causes the base station104-1to fail to successfully receive at least the M-th segment. That is, the base station104-1successfully receives only the first L segments, where 0<L<M≤N. The UE102detects920the failure (e.g., as discussed above with reference toFIG.2), but does not know how many segments the base station104-1successfully received prior to the failure (i.e., does not know the value of L). In response to detecting the failure, the UE102determines932to initiate an RRC connection reestablishment procedure with a new base station (i.e., the base station104-2). The UE102then transmits934an RRCReestablishmentRequest message to the base station104-2.

If the base station104-2does not have context information for the UE102(e.g., the “UE Context” as defined by the 5G specification) when receiving the RRCReestablishmentRequest message from the UE102, the base station104-2transmits936a RETRIEVE UE CONTEXT REQUEST message to the base station104-1, and the base station104-1responds by transmitting938to the base station104-2the context information for the UE102in a RETRIEVE UE CONTEXT RESPONSE message. The base station104-1includes the successfully received segments of the RRC PDU (i.e., the first L segments) in the RETRIEVE UE CONTEXT RESPONSE message. In some implementations, the base station104-1includes not only the segments themselves, but also an indication of the number of segments received, in the RETRIEVE UE CONTEXT RESPONSE message. For example, the base station104-1may include in the message a field containing the number L (the number of segments successfully received by base station104-1), the number L+1 (the number of the next segment that will be needed by base station104-2), or another suitable indicator of how many segments were successfully received by the base station104-1.

Referring now toFIG.9B, the base station104-2transmits940an RRCReestablishment message to the UE102, and the UE102responds by transmitting942an RRCReestablishmentComplete message to the base station104-2. Thereafter, the base station104-2determines960to initiate the RRC Procedure A (e.g., the UE capability transfer procedure), and transmits962another RRC Message A (e.g., another UECapabilityEnquiry message) to the UE102. In this RRC Message A, however, the base station104-2includes a request for the (L+1)-th segment of the RRC PDU (i.e., the (L+1)-th segment of RRC Response Message A). As noted above in connection withFIG.8, the request may take any suitable form that can convey to the UE102that the base station104-2still needs the (L+1)-th through the N-th segments.

In response to receiving and processing this RRC Message A, including the request for the (L+1)-th segment, the UE102sequentially transmits (964-(L+1) through964-N) the (L+1)-th through N-th segments of the RRC Response Message A to the base station104-2. Thus, despite the radio link failure, and despite the UE102not re-transmitting at least some of the first M segments, the base station104-2can successfully receive all N segments, and assemble all N segments into the complete RRC PDU.

As noted throughout the above discussion, in any of the implementations and scenarios ofFIGS.2-9, the RRC Message A may be a UECapabilityEnquiry message and the RRC Response Message A may be a UECapabilityInformation message. Moreover, in some implementations, the RRC PDU may be a UL-DCCH-MESSAGE that includes the UECapabilityInformation message. Alternatively, the RRC PDU may be the UECapabilityInformation message itself.

In still other implementations, the RRC Procedure A may be a UE Information procedure (e.g., as defined by the 5G specification), in which case the RRC Message A may be a UEInformationRequest message and the RRC Response Message A may be a UEInformationResponse message. In one such implementation, the RRC PDU may be a UL-DCCH-MESSAGE that includes the UEInformationResponse message. Alternatively, the RRC PDU may be the UEInformationResponse message itself.

Further, in some implementations, the RRC Message A may include information (e.g., a field or an information element) indicating that the UE102is permitted to transmit the RRC Response Message A (e.g., the UE capabilities) in segments. If the UE102receives an RRC Message A that does not include that information element, the UE102cannot segment the RRC Response Message A (e.g., such that transmission212-1,312-1,412-1,512-1,612-1,712-1,812-1or912-1must include the entire RRC Response Message A).

Additionally, in some implementations, the RRC Message A may include a transaction identifier and the RRC Response Message A may include the same transaction identifier. Each RRC Message A may include a different transaction identifier, and each RRC Response Message A may include the same transaction identifier as the corresponding RRC Message A. Moreover, each segment of an RRC Response Message A may include the same transaction identifier. In one implementation, each segment of an RRC Response Message A (or each segment of an RRC PDU including the RRC Response Message A) may include a segment number indicating an order of the segment in the sequence. In this implementation, the UE102may be allowed to transmit segments of the RRC Response Message A (or segments of an RRC PDU including the RRC Response Message A) out of sequence. In another implementation, the last segment of an RRC Response Message A may include an indication that the segment is the last segment.

Further, in some implementations, the UE102includes each segment of the RRC Response Message A (or each segment of an RRC PDU including the RRC Response Message A) in a new RRC message. In one implementation, the new RRC message may include a segment number indicating an order of the segment in the sequence. In this implementation, the UE102may be allowed to transmit segments of the RRC Response Message A (or segments of an RRC PDU including the RRC Response Message A) out of sequence. In another implementation, a new RRC message includes the last segment of the RRC Response Message A (or the last segment of an RRC PDU including the RRC Response Message A), and also includes an indication that the new RRC message includes the last segment of the RRC Response Message A. In other implementations, instead of utilizing a new RRC message, the UE102includes an indication of each segment number of the RRC Response Message A (or each segment number of an RRC PDU including the RRC Response Message A) in the RRC Response Message A, e.g., by using a critical extensions field/information element of the RRC Response Message A.

Also in any of the implementations and scenarios discussed above in connection withFIGS.2-9, the RAN104may utilize transaction identifiers to determine which RRC response messages (e.g., RRC Response Message A) transmitted by the UE102correspond to which RRC messages (e.g., RRC Message A) transmitted by the RAN104. In some implementations, for example, the RAN104(e.g., base station104-1) sets a transaction identifier to a first value, and includes the transaction identifier in the first RRC Message A (e.g., in transmission204,304,404,504,604,704,804or904). In response, the UE102sets a transaction identifier to the first value, and includes the transaction identifier somewhere in the RRC Response Message A (e.g., for transmission212,312,412,512,612,712,812or912). By inspecting this transaction indicator, the RAN104(e.g., base station104-1) may determine that the RRC Response Message A belongs to the same transaction as the first RRC Message A.

Alternatively, the UE102may include the transaction indicator in each segment of RRC Response Message A, such that the RAN104(e.g., base station104-1) may determine that each segment of the RRC Response Message A belongs to the same transaction as the first RRC Message A. In still other implementations, the UE102does not include the transaction indicator associated with the RRC Message A in any segment of the RRC Response Message A. For example, the UE102may include a different transaction indicator/value in RRC Response Message A or its segments, or may not include any transaction indicator. In these implementations, the RAN104may not know that the RRC Response Message A (or the segments thereof) and the RRC Message A belong to the same transaction until and unless the RAN104assembles all of the segments into the complete RRC PDU and subsequently obtains the RRC Response Message A from the RRC PDU. In some of the implementations described above, the RAN104is unable to assemble segments of an RRC Response Message A that include different transaction indicators.

Also, in any of the scenarios discussed above that involve a complete RRC connection reestablishment procedure, the RAN104(e.g., base station104-2) may transmit an RRCReconfiguration message to the UE102before transmitting the second RRC Message A to the UE102(e.g., in transmission362or962), and after transmitting an RRCReestablishment message to the UE102(e.g., in transmission340or940). The UE102may then respond by transmitting an RRCReconfigurationComplete message to the UE RAN104(e.g., the base station104-2), e.g., as in transmission342or942. The RAN104(e.g., the base station104-2) may then transmit the second RRC Message A to the UE102(e.g., in transmission362or962) after receiving the RRCReconfigurationComplete message.

Referring now toFIG.10, an example method1000for managing communication of a segmented RRC message can be implemented in a user device (e.g., by processing hardware120of the UE102) configured to communicate with a first base station (e.g., the base station104-1) via a radio link. In the method1000, the segmented RRC message includes N segments (e.g., within N respective segments of an RRC PDU), where N is an integer greater than one. The segmented RRC message may be a message indicating capabilities of the user device (e.g., a UECapabilityInformation message), for example.

At block1002of the method1000, the user device transmits the first M segments of the segmented RRC message to the first base station, where M is an integer greater than zero and less than N. As a more specific example, the transmission may include the transmissions212-1through212-M ofFIG.2, the transmissions312-1through312-M ofFIG.3A, the transmissions412-1through412-M ofFIG.4A, the transmissions512-1through512-M ofFIG.5A, the transmissions612-1through612-M ofFIG.6A, the transmissions712-1through712-M ofFIG.7A, the transmissions812-1through812-M ofFIG.8, or the transmissions912-1through912-M ofFIG.9A.

At block1004, before transmitting the (M+1)-th segment of the segmented RRC message, the user device detects a failure of the radio link. As a more specific example, the detection may include the detection220ofFIG.2, the detection320ofFIG.3A, the detection420ofFIG.4A, the detection520ofFIG.5A, the detection620ofFIG.6A, the detection720ofFIG.7A, the detection820ofFIG.8, or the detection920ofFIG.9A. The user device may detect the failure almost immediately after the failure occurs, or after some delay. Thus, the first base station may fail to receive only the M-th segment transmitted by the user device, or may fail to receive multiple segments transmitted by the user device. In either case, the user device may be unaware of how many segments the first base station failed to receive.

At block1006, after detecting the failure of the radio link, the user device transmits at least the last N−M+1 segments of the segmented RRC message to either the first base station or a second base station (e.g., the base station104-1or the base station104-2). As a more specific example, the transmission may include the transmissions264-1through264-N ofFIG.2, the transmissions364-1through364-N ofFIG.3B, the transmissions464-1through464-N ofFIG.4B, the transmissions564-1through564-N ofFIG.5B, the transmissions664-1through664-N ofFIG.6B, the transmissions764-1through764-N ofFIG.7B, the transmissions864-(L+1) through864-N ofFIG.8, or the transmissions964-(L+1) through964-N ofFIG.9B.

In some implementations and/or scenarios, the method1000includes one or more additional blocks not shown inFIG.10. For example, the method1000may include an additional block, occurring before block1006, in which the user device receives, from the first base station or the second base station, an RRC message indicating that the first base station received the first L segments of the segmented RRC message, where L is an integer greater than zero and less than M. In this implementation/scenario, block1006may include transmitting only the last N-L segments of the segmented RRC message, and may occur in response to receiving the RRC message from the first or second base station. As a more specific example, the RRC message that the user device receives from the first or second base station may be the RRC Message A transmitted in transmission862ofFIG.8or transmission962ofFIG.9B.

As another example, the method1000may include, before block1002, an additional block in which the user device receives an RRC message from the first base station via the radio link, and block1002may occur in response to the user device receiving the RRC message. As a more specific example, the RRC message that the user device receives from the first base station may be the RRC Message A transmitted in transmission204ofFIG.2, transmission304ofFIG.3A, transmission404ofFIG.4A, transmission504ofFIG.5A, transmission604ofFIG.6A, transmission704ofFIG.7A, transmission804ofFIG.8, or transmission904ofFIG.9A.

As another example, the method1000may include an additional block in which the user device, in response to detecting the failure of the radio link at block1004, initiates (with either the first or second base station) either an RRC connection reestablishment procedure or an RRC connection establishment procedure. In such an implementation, block1006may occur after the user device and the first or second base station establish or reestablish an RRC connection. As a more specific example, the user device may initiate the RRC connection establishment or reestablishment procedure via the transmission334ofFIG.3Aor the transmission934ofFIG.9A.

Referring now toFIG.11, an example method1100for managing communication of a segmented RRC message can be implemented in a base station (e.g., by processing hardware160of the base station104-1or similar processing hardware of the base station104-2) configured to communicate with a user device (e.g., the UE102) via a radio link. In the method1100, the segmented RRC message includes N segments (e.g., within N respective segments of an RRC PDU), where N is an integer greater than one. The segmented RRC message may be a message indicating capabilities of the user device (e.g., a UECapabilityInformation message), for example.

At block1102of the method1100, the base station receives the first L segments of the segmented RRC message from either the user device or another base station, where L is an integer greater than zero and less than N. As a more specific example, in an implementation and/or scenario where the base station receives the first L segments from the user device, the base station may receive the L segments in the transmissions812-1through812-L ofFIG.8or the transmissions912-1through912-L ofFIG.9A(where it is understood that L is less than M). As another example, in implementations and/or scenarios where the base station instead receives the first L segments from another base station, the base station may receive the L segments in the transmission938ofFIG.9A.

At block1104, after a failure of the radio link, the base station generates an RRC message indicating that the base station received the first L segments. For example, the RRC message may specify the number L (the last successfully received segment), or the number L+1 (the next segment that the base station needs), etc. Block1104may occur after the user device and the base station establish or reestablish an RRC connection, for example.

At block1106, the base station transmits the RRC message to the user device to cause the user device to transmit at least the last N-L segments of the segmented RRC message to the base station. As a more specific example, the transmission by the base station may be the transmission862ofFIG.8or the transmission962ofFIG.9B, and the triggered transmission (by the user device) may include the transmissions864-(L+1) through864-N ofFIG.8or the transmissions964-(L+1) through964-N ofFIG.9B.

In some implementations and/or scenarios, the method1100includes one or more additional blocks not shown inFIG.11. For example, the method1100may include an additional block, occurring before block1102, in which the base station transmits, to the user device, an RRC request message that requests the segmented RRC message. As a more specific example, the transmission may be the transmission804ofFIG.8or the transmission904ofFIG.9A.

By way of example, and not limitation, the disclosure herein contemplates at least the following aspects:

Aspect 1—A method, in a user device configured to communicate with a first base station via a radio link, for managing communication of a segmented radio resource control (RRC) message that includes N segments, the method comprising: transmitting a first M segments of the segmented RRC message to the first base station, M being an integer greater than zero and less than N; detecting, by processing hardware of the user device and before transmitting an (M+1)-th segment of the segmented RRC message, a failure of the radio link; and after detecting the failure of the radio link, transmitting at least a last N−M+1 segments of the segmented RRC message to either the first base station or a second base station.

Aspect 2—The method of aspect 1, wherein transmitting at least the last N−M+1 segments of the segmented RRC message includes transmitting the N segments.

Aspect 3—The method of aspect 1, wherein transmitting at least the last N−M+1 segments of the segmented RRC message includes transmitting only a subset of the N segments.

Aspect 4—The method of aspect 1, further comprising: before transmitting at least the last N−M+1 segments, receiving, from the first base station or the second base station, an RRC message indicating that the first base station received a first L segments of the segmented RRC message, L being an integer greater than zero and less than M, wherein transmitting at least the last N−M+1 segments includes transmitting only a last N-L segments of the segmented RRC message, and occurs in response to receiving the RRC message.

Aspect 5—The method of any one of aspects 1 through 4, further comprising: receiving an RRC message from the first base station via the radio link, wherein transmitting the first M segments occurs in response to receiving the RRC message.

Aspect 6—The method of aspect 5, wherein: the RRC message is a message requesting user device capability information; and the segmented RRC message is a message indicating capabilities of the user device.

Aspect 7—The method of aspect 5 or 6, further comprising: after detecting the failure of the radio link, receiving an additional RRC message from the first base station or the second base station, wherein transmitting at least the last N−M+1 segments occurs in response to receiving the additional RRC message.

Aspect 8—The method of any one of aspects 1 through 7, wherein the segmented RRC message is included in a segmented RRC protocol data unit (PDU).

Aspect 9—The method of any one of aspects 1 through 8, further comprising: in response to detecting the failure of the radio link, initiating, with either the first base station or the second base station, either an RRC connection reestablishment procedure or an RRC connection establishment procedure, wherein transmitting at least the last N−M+1 segments occurs after the user device and either the first base station or the second base station establish or reestablish an RRC connection.

Aspect 10—The method of any one of aspects 1 through 9, wherein: transmitting the first M segments includes, for each segment of the first M segments, transmitting a message including the segment and a segment number indicating an order of the segment in the segmented RRC message; and transmitting at least the last N−M+1 segments includes, for each segment of at least an (M+1)-th segment through an (N−1)-th segment of the segmented RRC message, transmitting a message including the segment and a segment number indicating an order of the segment in the segmented RRC message.

Aspect 11—The method of any one of aspects 1 through 10, wherein transmitting at least the last N−M+1 segments includes transmitting a message including an N-th segment of the segmented RRC message and an indication that the message includes a last segment of the segmented RRC message.

Aspect 12—A user device comprising processing hardware configured to execute a method according to any of one of aspects 1 through 11.

Aspect 13—A method, in a base station configured to communicate with a user device via a radio link, for managing communication of a segmented radio resource control (RRC) message that includes N segments, the method comprising: receiving a first L segments of the segmented RRC message from either the user device or another base station, L being an integer greater than zero and less than N; after a failure of the radio link, generating, by processing hardware of the base station, an RRC message indicating that the base station received the first L segments; and transmitting the RRC message to the user device to cause the user device to transmit at least a last N-L segments of the segmented RRC message to the base station.

Aspect 14—The method of aspect 13, wherein causing the user device to transmit at least the last N-L segments includes causing the user device to transmit only the last N-L segments.

Aspect 15—The method of aspect 13 or 14, further comprising: before receiving the first L segments, transmitting, to the user device, an RRC request message that requests the segmented RRC message.

Aspect 16—The method of aspect 15, wherein the RRC message indicating that the base station received the first L segments is an additional RRC request message.

Aspect 17—The method of aspect 16, wherein: the RRC request message and the additional RRC request message both request user device capability information; and the segmented RRC message is a message indicating capabilities of the user device.

Aspect 18—The method of any one of aspects 13 through 17, wherein the segmented RRC message is included in a segmented RRC protocol data unit (PDU).

Aspect 19—The method of any one of aspects 13 through 18, wherein generating the RRC message indicating that the base station received the first L segments occurs after the user device and the base station establish or reestablish an RRC connection.

Aspect 20—The method of any one of aspects 13 through 19, wherein receiving the first L segments includes receiving the first L segments from the user device in a sequential manner.

Aspect 21—The method of any one of aspects 13 through 19, wherein receiving the first L segments includes receiving the first L segments from the other base station in a single message that provides information about the user device.

Aspect 22—The method of any one of aspects 13 through 21, wherein receiving the first L segments includes, for each segment of the first L segments, receiving a message including the segment and a segment number indicating an order of the segment in the segmented RRC message.

Aspect 23—The method of any one of aspects 13 through 22, further comprising: receiving at least a last N-L segments from the user device, wherein receiving the last N-L segments from the user device includes receiving a message including an N-th segment of the segmented RRC message and an indication that the message includes a last segment of the segmented RRC message.

Aspect 24—A base station comprising processing hardware configured to execute a method according to any of one of aspects 13 through 23.

The following additional considerations apply to the foregoing discussion.

A user device in which the techniques of this disclosure can be implemented (e.g., the UE102) can be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device can operate as an internet-of-things (IoT) device or a mobile-internet device (MID). Depending on the type, the user device can include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

Certain implementations are described in this disclosure as including logic or a number of components or modules. Modules may can be software modules (e.g., code stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module can comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

When implemented in software, the techniques can be provided as part of the operating system, a library used by multiple applications, a particular software application, etc. The software can be executed by one or more general-purpose processors or one or more special-purpose processors.

Upon reading this disclosure, those of skill in the art will appreciate, through the principles disclosed herein, still additional alternative structural and functional designs for managing the communication of segmented RRC messages. Thus, while particular implementations and applications have been illustrated and described, it is to be understood that the disclosed implementations are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those of ordinary skill in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.