Cell handover during radio resource control resume

Abstract

A method performed by a user equipment (UE) includes receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state. The method includes performing an evaluation of an idle / inactive measurement (IM) reporting configuration to determine to send a IM report. The method includes carrying out a random access channel (RACH) procedure towards the source access node for an RRC resume, during which an RRC resume request message and the IM report are sent to the source access node. And the method includes receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, for the UE to resume an RRC connection with the source access node or perform a handover to a target access node.

Description

CELL HANDOVER DURING RADIO RESOURCE CONTROL RESUMETECHNOLOGICAL FIELD

[0001] The present disclosure relates generally to telecommunications and, in particular, cell handover during radio resource control (RRC) resume.BACKGROUND

[0002] A telecommunications system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and / or other nodes by providing carriers between the various entities involved in the communications path. A telecommunications system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and / or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

[0003] In a wireless telecommunications system at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

[0004] A user can access the telecommunications system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, forexample enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and / or receive communications on the carrier.

[0005] The telecommunications system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and / or parameters which shall be used for the connection are also typically defined. One example of a telecommunications system is the Universal Mobile Telecommunications System (UMTS). Other examples of telecommunications systems are Long-Term Evolution (LTE), LTE Advanced and the so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3 GPP).BRIEF SUMMARY

[0006] Example implementations of the present disclosure are directed to telecommunications and, in particular, cell handover during radio resource control (RRC) resume. The present disclosure includes, without limitation, the following example implementations.

[0007] Some example implementations provide an apparatus implemented by a source access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: send a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receive an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; make a determination to trigger a handover based on an evaluation of the IM report; and send an RRC resume message to the UE that includes a handover configuration for the UE to perform thehandover, enter an RRC connected state and resume the RRC connection with a target access node.

[0008] Some example implementations provide an apparatus implemented by a source access node, the apparatus comprising: means for sending a radio resource control (RRC) suspend message to an user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; means for making a determination to trigger a handover based on an evaluation of the IM report; and means for sending an RRC resume message to the UE that includes a handover configuration for the UE to perform the handover, enter an RRC connected state and resume the RRC connection with a target access node.

[0009] Some example implementations provide a method performed by a source access node, the method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; making a determination to trigger a handover based on an evaluation of the IM report; and sending an RRC resume message to the UE that includes a handover configuration for the UE to perform the handover, enter an RRC connected state and resume the RRC connection with a target access node.

[0010] Some example implementations provide an apparatus implemented by a user equipment (UE), the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: receive a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; send an RRC resume request to the source access node toresume the RRC connection based on a detected connection request; send an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; receive an RRC resume message from the source access node that includes a handover configuration; and perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0011] Some example implementations provide an apparatus implemented by an user equipment (UE), the apparatus comprising: means for receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; means for sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; means for receiving an RRC resume message from the source access node that includes a handover configuration; and means for performing the handover, entering an RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration.

[0012] Some example implementations provide a method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the sourceaccess node to make a determination whether to trigger a handover to a target access node; receiving an RRC resume message from the source access node that includes a handover configuration; and performing the handover, entering an RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration.

[0013] Some example implementations provide an apparatus implemented by a target access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: receive a handover request message from a source access node to request a handover of a user equipment (UE) from a source access node in connection with an RRC resume request from the UE in an RRC inactive mode, the handover request message including an indication that the handover is for the UE to resume an RRC connection with the target access node; perform an admission control based on the handover request message; and based on the admission control, send a handover response message to the source access node that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE to perform the handover to the target access node; and receive an RRC resume complete message from the UE based on an RRC resume message from the source access node to the UE that includes the handover configuration, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0014] Some example implementations provide an apparatus implemented by a target access node, the apparatus comprising: means for receiving a handover request message from a source access node to request a handover of an user equipment (UE) from a source access node in connection with an RRC resume request from the UE in an RRC inactive mode, the handover request message including an indication that the handover is for the UE to resume an RRC connection with the target access node; means for performing an admission control based on the handover request message; and based on the admission control, means for sending a handover response message to the source access node that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE to perform the handover to the target access node; and means forreceiving an RRC resume complete message from the UE based on an RRC resume message from the source access node to the UE that includes the handover configuration, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0015] Some example implementations provide a method performed by a target access node, the method comprising: receiving a handover request message from a source access node to request a handover of a user equipment (UE) from a source access node in connection with an RRC resume request from the UE in an RRC inactive mode, the handover request message including an indication that the handover is for the UE to resume an RRC connection with the target access node; performing an admission control based on the handover request message; and based on the admission control, sending a handover response message to the source access node that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE to perform the handover to the target access node; and receiving an RRC resume complete message from the UE based on an RRC resume message from the source access node to the UE that includes the handover configuration, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0016] Some example implementations provide an apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: send a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receive an IM report from the UE in connection with an RRC resume request of a random access channel (RACH) procedure, and when a reporting event of the IM reporting configuration is fulfilled; make a determination to trigger a handover based on an evaluation of the IM report; and based on the RRC resume request and the determination, send a handover request message to a target access node; and send an RRC resume message to the UE that includes a handover configuration and an indication to terminate the RACH procedure, for the UE to terminate the RACHprocedure and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node.

[0017] Some example implementations provide an apparatus comprising: means for sending a radio resource control (RRC) suspend message to an user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for receiving an IM report from the UE in connection with an RRC resume request of a random access channel (RACH) procedure, and when a reporting event of the IM reporting configuration is fulfilled; means for making a determination to trigger a handover based on an evaluation of the IM report; and based on the RRC resume request and the determination, means for sending a handover request message to a target access node; and means for sending an RRC resume message to the UE that includes a handover configuration and an indication to terminate the RACH procedure, for the UE to terminate the RACH procedure and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node.

[0018] Some example implementations provide a method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request of a random access channel (RACH) procedure, and when a reporting event of the IM reporting configuration is fulfilled; making a determination to trigger a handover based on an evaluation of the IM report; and based on the RRC resume request and the determination, sending a handover request message to a target access node; and sending an RRC resume message to the UE that includes a handover configuration and an indication to terminate the RACH procedure, for the UE to terminate the RACH procedure and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node.

[0019] Some example implementations provide an apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: receive a radio resource control (RRC) suspend message from a source access node to trigger a transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; initiate a random access channel (RACH) procedure towards the source access node; send an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; send an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; receive an RRC resume message from the source access node that includes a handover configuration and an indication to terminate the RACH procedure; terminate the RACH procedure towards the source access node; and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0020] Some example implementations provide an apparatus comprising: means for receiving a radio resource control (RRC) suspend message from a source access node to trigger a transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for initiating a random access channel (RACH) procedure towards the source access node; means for sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; means for sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; means for receiving an RRC resume message from the source access node that includes a handover configuration and an indication to terminate the RACH procedure; means for terminatingthe RACH procedure towards the source access node; and means for carrying out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0021] Some example implementations provide a method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger a transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; initiating a random access channel (RACH) procedure towards the source access node; sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; receiving an RRC resume message from the source access node that includes a handover configuration and an indication to terminate the RACH procedure; terminating the RACH procedure towards the source access node; and carrying out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0022] Some example implementations provide an apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: receive a handover request message from a source access node to request a handover of a user equipment (UE) from the source access node in connection with an RRC resume request from the UE in an RRC inactive state, the handover request message including an indication that the handover is for the UE to resume an RRC connection with a target access node; perform admission control to establish an RRC connection with the UE; and carry out a random access channel (RACH) procedure with the UE during which an RRC resume complete message is received from the UE based on an RRC resume message of an earlier RACH procedure from the source access node to theUE that includes the handover configuration and an indication to terminate the earlier RACH procedure, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0023] Some example implementations provide an apparatus comprising: means for receiving a handover request message from a source access node to request a handover of an user equipment (UE) from the source access node in connection with an RRC resume request from the UE in an RRC inactive state, the handover request message including an indication that the handover is for the UE to resume an RRC connection with a target access node; means for performing admission control to establish an RRC connection with the UE; and means for carrying out a random access channel (RACH) procedure with the UE during which an RRC resume complete message is received from the UE based on an RRC resume message of an earlier RACH procedure from the source access node to the UE that includes the handover configuration and an indication to terminate the earlier RACH procedure, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0024] Some example implementations provide a method comprising: receiving a handover request message from a source access node to request a handover of a user equipment (UE) from the source access node in connection with an RRC resume request from the UE in an RRC inactive state, the handover request message including an indication that the handover is for the UE to resume an RRC connection with a target access node; performing admission control to establish an RRC connection with the UE; and carrying out a random access channel (RACH) procedure with the UE during which an RRC resume complete message is received from the UE based on an RRC resume message of an earlier RACH procedure from the source access node to the UE that includes the handover configuration and an indication to terminate the earlier RACH procedure, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0025] Some example implementations provide an apparatus implemented by a user equipment (UE), the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least onememory, and execute the instructions to cause the apparatus to at least: receive a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; perform an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request; send a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; carry out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and receive an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0026] Some example implementations provide an apparatus implemented by an user equipment (UE), the apparatus comprising: means for receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for performing an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request; means for sending a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; means for carrying out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and means for receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRCconnection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0027] Some example implementations provide a method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; performing an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request; sending a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; carrying out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0028] Some example implementations provide an apparatus implemented by a source access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: send a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receive an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; perform an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, send an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter anRRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0029] Some example implementations provide an apparatus implemented by a source access node, the apparatus comprising: means for sending a radio resource control (RRC) suspend message to an user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; means for receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; means for performing an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, means for sending an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0030] Some example implementations provide a method performed by a source access node, the method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; performing an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, sending an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0031] These and other features, aspects, and advantages of the present disclosure will be apparent from a reading of the following detailed description together with theaccompanying figures, which are briefly described below. The present disclosure includes any combination of two, three, four or more features or elements set forth in this disclosure, regardless of whether such features or elements are expressly combined or otherwise recited in a specific example implementation described herein. This disclosure is intended to be read holistically such that any separable features or elements of the disclosure, in any of its aspects and example implementations, should be viewed as combinable unless the context of the disclosure clearly dictates otherwise.

[0032] It will therefore be appreciated that this Brief Summary is provided merely for purposes of summarizing some example implementations so as to provide a basic understanding of some aspects of the disclosure. Accordingly, it will be appreciated that the above described example implementations are merely examples and should not be construed to narrow the scope or spirit of the disclosure in any way. Other example implementations, aspects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying figures which illustrate, by way of example, the principles of some described example implementations.

[0033] BRIEF DESCRIPTION OF THE FIGURE(S)

[0034] Having thus described example implementations of the disclosure in general terms, reference will now be made to the accompanying figures, which are not necessarily drawn to scale, and wherein:

[0035] FIG. 1 illustrates a telecommunications system that includes one or more public land mobile networks (PLMNs) coupled to one or more external data networks, according to some example implementations of the present disclosure;

[0036] FIG. 2 illustrates a deployment of a PLMN, according to some example implementations;

[0037] FIG. 3 illustrates a signaling chart of a radio resource control (RRC) resume procedure;

[0038] FIG. 4 is a line chart of signal conditions of first and second cells for a user equipment (UE) performing an RRC resume followed by a handover, illustrating a problem to be solved by example implementations;

[0039] FIG. 5 illustrates a signaling chart of the RRC resume procedure that is unsuccessful when the UE performs a cell reselection before the RRC resume procedure is completed;

[0040] FIG. 6 illustrates a delay introduced when the UE when cell reselection occurs during an RRC resume;

[0041] FIG. 7 illustrates is a line chart of signal conditions for the first and second cells of FIG. 4, in which the UE performs handover during RRC resume, according to some example implementations;

[0042] FIGS. 8 A and 8B illustrate a signaling chart of procedures for handover during a RRC resume, according to some example implementations;

[0043] FIG. 9 is a flowchart of a process for evaluation of an idle / inactive measurement (IM) reporting configuration performed by a UE, according to some example implementations;

[0044] FIG. 10 is a flowchart of a process for evaluation of an IM report performed by a source radio access node, according to some example implementations;

[0045] FIG. 11 is a flowchart of a process for admission control performed by a target radio access node, according to some example implementations;

[0046] FIG. 12 is a flowchart of a process for evaluation of an RRC resume message performed by a UE, according to some example implementations;

[0047] FIGS. 13Aand 13B illustrate a signaling chart of procedures for a random access channel (RACH)-based handover during a RRC resume, according to some example implementations;

[0048] FIG. 14 is a flowchart illustrating various steps in a method performed by a source access node, according to various example implementations;

[0049] FIG. 15 is a flowchart illustrating various steps in a method performed by a user equipment (UE), according to various example implementations;

[0050] FIGS. 16A- 16F are flowcharts illustrating various steps in a method performed by a target access node, according to various example implementations;

[0051] FIG. 17 is a flowchart illustrating various steps in a method performed by a source access node, according to various example implementations;

[0052] FIG. 18 A and 18B are flowcharts illustrating various steps in a method performed by a UE, according to various example implementations;

[0053] FIGS. 19Aand 19B are flowcharts illustrating various steps in a method performed by a target access node, according to various example implementations;

[0054] FIG. 20 is a flowchart illustrating various steps in a method performed by aUE, according to various example implementations;

[0055] FIG. 21 is a flowchart illustrating various steps in a method performed by a source access node, according to various example implementations; and

[0056] FIG. 22 illustrates an apparatus according to some example implementations.DETAILED DESCRIPTION

[0057] Some implementations of the present disclosure will now be described more fully hereinafter with reference to the accompanying figures, in which some, but not all implementations of the disclosure are shown. Indeed, various implementations of the disclosure may be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these example implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout.

[0058] Unless specified otherwise or clear from context, references to first, second or the like should not be construed to imply a particular order. A feature described as being above another feature (unless specified otherwise or clear from context) may instead be below, and vice versa; and similarly, features described as being to the left of another feature else may instead be to the right, and vice versa. Also, while reference may be made herein to quantitative measures, values, geometric relationships or the like, unless otherwise stated, any one or more if not all of these may be absolute or approximate to account for acceptable variations that may occur, such as those due to engineering tolerances or the like.

[0059] As used herein, unless specified otherwise or clear from context, the “or” of a set of operands is the “inclusive or” and thereby true if and only if one or more of the operands is true, as opposed to the “exclusive or” which is false when all of the operandsare true. Thus, for example, “[A] or [B]” is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Further, the articles “a” and “an” mean “one or more,” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, it should be understood that unless otherwise specified, the terms “data,” “content,” “digital content,” “information,” and similar terms may be at times used interchangeably. The term “network” may refer to a group of interconnected computers including clients and servers; and within a network, these computers may be interconnected directly or indirectly by various means including via one or more switches, routers, gateways, access points or the like.

[0060] Reference may be made herein to terms specific to a particular system, architecture or the like, but it should be understood that example implementations of the present disclosure may be equally applicable to any of a number of systems, architectures and the like. For example, reference may be made to 3 GPP technologies such as Global System for Mobile Communications (GSM), UMTS, LTE, LTE Advanced, 5GNR, 5G Advanced and 6G; however, it should be understood that example implementations of the present disclosure may be equally applicable to non-3GPP technologies such as IEEE 802, Bluetooth and Bluetooth Low Energy.

[0061] Further, as used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry); (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); or (c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0062] The above definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their)accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0063] FIG. 1 illustrates a telecommunications system 100 according to various example implementations of the present disclosure. The telecommunications system generally includes one or more telecommunications networks. As shown, for example, the system includes one or more public land mobile networks (PLMNs) 102 coupled to one or more other external data networks 104 - notably including a wide area network (WAN) such as the Internet. Each of the PLMNs includes a core network(CN) 106 backbone such as the Evolved Packet Core (EPC) of LTE, the 5G core network (5GC) or the like; and each of the core networks and the Internet are coupled to one or more radio access networks (RANs) 108, air interfaces or the like that implement one or more radio access technologies (RATs). As used herein, a “network device” refers to any suitable device at a network side of a telecommunications network. Examples of suitable network devices are described in greater detail below.

[0064] In addition, the system includes one or more radio units that may be varyingly known as user equipment (UE) 110, terminal device, terminal equipment, mobile station or the like. The UE is generally a device configured to communicate with a network device or a further UE in a telecommunications network. The UE may be a portable computer (e.g., laptop, notebook, tablet computer), mobile phone (e.g., cell phone, smartphone), wearable computer (e.g., smartwatch), or the like. In other examples, the UE may be an Internet of things (loT) device, an industrial loT (IIoT device), a vehicle equipped with a vehicle-to-everything (V2X) communication technology, or the like. In some examples, as referenced by 3 GPP, the UE may be a narrowband loT (NB-IoT) device, an enhanced machine-type communication (eMTC) device, a reduced capability (RedCap) device, an ambient loT device, or the like.

[0065] In operation, these UEs 110 may be configured to connect to one or more of the RANs 108 according to their particular radio access technologies to thereby access a particular CN 106 of a PLMN 102, or to access one or more of the external data networks 104 (e.g., the Internet). The external data network may be configured to provideInternet access, operator services, 3rd party services, etc. For example, the International Telecommunication Union (ITU) has classified 5G mobile network services into three categories: enhanced mobile broadband (eMBB), ultra- reliable and low-latency communications (URLLC), and massive machine type communications (mMTC) or massive internet of things (MIoT).

[0066] Examples of radio access technologies include 3 GPP radio access technologies such as GSM, UMTS, LTE, LTE Advanced, 5GNR, 5G Advanced, and 6G. Other examples of radio access technologies include IEEE 802 technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.15 (including 802.15.1 (WPAN / Bluetooth), 802.15.4 (Zigbee) and 802.15.6 (WBAN)), Bluetooth, Bluetooth Low Energy (BLE), ultra wideband (UWB), and the like. Generally, a radio access technology may refer to any 2G, 3G, 4G, 5G, 6G or higher generation mobile communication technology and their different versions, as well as to any other wireless radio access technology that may be arranged to interwork with such a mobile communication technology to provide access to the CN 106 of a mobile network operator (MNO).

[0067] In various examples, a RAN 108 may be configured as one or more macrocells, microcells, picocells, femtocells or the like. The RAN may generally include one or more radio access nodes (at times more simply referred to as access nodes) that are configured to interact with UEs 110. In various examples, a radio access node may be referred to as a base station (BS), access point (AP), base transceiver station (BTS), Node B (NB), evolved NB (eNB), macro BS, NB (MNB) or eNB (MeNB), home BS, NB (HNB) or eNB (HeNB), next generation NB (gNB), enhanced gNB (en-gNB), next generation eNB (ng-eNB), or the like. The RAN may include some type of network controlling / governing entity responsible for control of the radio access nodes. The network controlling / governing entity and radio access node may be separate or integrated into a single apparatus. The network controlling / governing entity may include processing circuity configured to carry out various management functions, etc. The processing circuity may be associated with a memory, computer-readable storage medium or database for maintaining information required in the management functions.

[0068] A RAN 108 may be centralized or distributed. In various examples, components of a RAN may be interconnected by Ethernet, Gigabit Ethernet,Asynchronous Transfer Mode (ATM), optical fiber, dark fiber, passive wavelength division multiplexing (WDM), WDM passive optical network (WDM-PON), optical transport network (OTN), time sensitive networking (TSN) and / or any other data link layer network, possibly including radio links. The RAN may be connected to a CN 106 through one or more gateways, network functions or the like.

[0069] As will be appreciated, a PLMN 102 may be deployed in a number of different manners. In a 4GLTE deployment, the EPC is the CN 106, and the evolved UMTS terrestrial radio access network (E-UTRAN) is the RAN 108; and the E-UTRAN includes one or more eNBs (radio access nodes) configured to connect UEs 110 to the E- UTRAN to thereby access the EPC. FIG. 2 illustrates a deployment 200, such as a 5G or 6G deployment. As shown, the 5GC 202 is the CN, and the next generation (NG) radio access network (NG-RAN) 204 is the RAN; and the NG-RAN includes one or more gNBs 206 (radio access nodes) configured to connect UEs to the NG-RAN to thereby access the 5GC. The term ‘gNB’ in 5G may correspond to the eNB in 4G LTE.

[0070] Some deployments of 4G LTE and 5G in particular are considered standalone (SA) deployments. Other deployments combine 4G LTE and 5G technologies, and are referred to as non-standalone (NSA) deployments. In some deployments, the E-UTRAN includes one or more ng-eNBs that are configured to communicate with the 5GC, and that may also be configured to communicate with one or more gNBs. Similarly, in another deployment, the NG-RAN may include one or more en-gNBs that are configured to communicate with the EPC, and that may also be configured to communicate with one or more eNBs. In various instances, a single UE 110, a dual-mode or multimode UE, may support multiple (two or more) RANs — thereby being configured to connect to multiple RANs, such as 4G LTE and 5G.

[0071] In some deployments, such as deployment 200, operations of the gNB 206 or other radio access node may be carried out, at least partly, in a central / centralized unit (CU), such as a server, host or node, operationally coupled to a distributed unit (DU), such as a radio head / node. It is also possible that node operations may be distributed among a plurality of servers, hosts or nodes. It should also be understood that the distribution of work between 5GC 202 (or other CN) operations and gNB (or other radio access node) operations may vary depending on implementation.

[0072] A 5G network architecture may be based on a so-called CU-DU split. One gNB-CU (central node) may control one or more gNB-DUs. The gNB-CU may control a plurality of spatially separated gNB-DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some example implementations, however, the gNB-DUs (also called DU) may include, for example, radio link control (RLC) 310, medium access control (MAC) layer 308 and a physical layer (PHY) 306, whereas the gNB-CU (also called a CU) may include the layers above the RLC layer 310, such as packet data convergence protocol (PDCP) layer 312, radio resource control (RRC) 316, and an internet protocol (IP) layer. Other functional splits are also possible. It is considered that a skilled person is familiar with the open systems interconnection (OSI) model and the functionalities within each layer.

[0073] In some example implementations, the server or CU may generate a virtual network through which the server communicates with the radio node. In general, virtual networking may involve a process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Such virtual network may provide flexible distribution of operations between the server and the radio head / node. In practice, any digital signal processing task may be performed in either the CU or the DU, and the boundary where the responsibility is shifted between the CU and the DU may be selected according to implementation.

[0074] As specified by 3 GPP, the RRC layer of the 5G radio protocol stack is responsible for various control functions such as synchronization, connection establishment and its management, facilitating security and reliable messaging, radio resource management, signaling handling, dedicated and broadcast network configuration management, mobility procedures paging notification.

[0075] The operation of the RRC is guided by a state machine which defines certain specific states that a UE 110 may be present in. The different states in the RRC state machine have different amounts of radio resources associated with them and these are the resources that the UE may use when the UE is present in each state. Since different amounts of resources are available at different states, the quality of the service that the user experiences and the energy consumption of the UE are influenced by this state machine. Relative to previous generations, 5G NR supplemented RRC idle (RRC IDLE)and RRC connected (RRC CONNECTED) states by an RRC inactive (RRC INACTIVE) state, which offers light connectivity with major power saving methods integrated into the state.

[0076] The RRC inactive state, introduced in 5G NR, is designed to address challenges of signaling overhead and latency that occur when the UE 110 transitions from the RRC idle state to the RRC connected state. The RRC inactive state provides a balance by allowing the UE to maintain similar power-saving as when the UE is in the RRC idle state, while still being prepared for prompt reconnection. In the RRC inactive state, the UE remains in a connection management (CM) connected state. In the CM connected state, the UE retains its access stratum (AS) context, which includes parameters and configurations that were established during the RRC connected state, for promptly resuming an RRC connection with minimal latency.

[0077] The RRC inactive state allows the UE 110 to perform cell re-selection measurements, similar to the RRC idle state, enabling the UE to move within a predefined area known as RAN notification area (RNA) without notifying the gNB node 206. The RNA is configured by a serving gNB node 206, allowing the UE to maintain mobility while in the RRC inactive state without triggering excessive signaling.

[0078] During the RRC inactive state, signaling radio bearers (SRBs) and data radio bearers (DRBs) are suspended, except for SRB0, which remains active to allow the UE 110 to receive signaling messages, such as paging messages, while minimizing battery consumption. In the RRC inactive state, the 5GC 202 maintains an NG signaling connection with the gNB node 206, as well as general packet radio service tunneling protocol-user plane (GTP-U) tunnels. Context information of the UE’s most recent RRC connection (i.e., during the RRC connected state) is stored in the UE and the last serving gNB node 206.

[0079] The RRC resume procedure involves transitioning a UE 110 from an RRC inactive state back to an RRC connected state with a gNB 206. FIG. 3 illustrates a signaling chart 300 of the RRC resume procedure between a UE and the gNB that provides a cell on which the UE is camped (e.g., the last serving cell of the UE).

[0080] As shown at step 301, a UE in the RRC inactive state sends an RRC resume request message to the gNB. This message includes a resume identity, which is associatedwith a previously configured temporary cell radio network temporary identifier (C- RNTI). Upon receiving the RRC resume request, the gNB at step 302 sends an RRC resume message back to the UE. This message includes an RRC resume configuration to reestablish the connection, similar to those in an RRC setup message. Once the UE successfully receives and applies the RRC resume configuration, the UE at step 303 sends an RRC resume complete message to the gNB, confirming the successful resumption of the RRC connection.

[0081] When a UE 110 is in RRC idle / inactive, the UE performs idle / inactive measurements (IM) of the gNB 206 as well as the neighboring gNBs. The measurements are for UE to make sure the UE is camped on the best cell and initiate cell reselection when a new best cell is identified based on the measurements. As shown in FIG. 3, for example, before receiving the RRC resume configuration in the RRC resume message at 302, the UE may initiate idle / inactive measurements as part of a cell reselection procedure, during which the UE my start a T319 timer to ensure the UE completes the RRC resume procedure within a specified timeframe. If the UE receives the RRC resume message (at step 302) during the cell reselection procedure, however, the UE stops the cell reselection procedure, as well as the T319 timer, and complete the RRC resume procedure with the gNB 206.

[0082] Another use of idle / inactive measurements is for early measurement reporting (EMR) when UE moves to RRC connected. With EMR, the UE 110 is configured to perform measurements of potential carriers for carrier aggregation (CA) or dual connectivity (DC) such as NR-DC or multi-radio DC (MR-DC), while in idle or inactive mode. The goal is to allow early setup of CA or DC by having the UE perform measurements of other carriers while in idle or inactive mode, and report these immediately after completion of RRC connection setup or during the RRC connection setup procedure. In this way, CA or DC may be setup at the same time the DRBs are setup.

[0083] As currently specified by 3GPP, handover (HO) of a UE 110 to a target cell during RRC resume is not possible after the UE receives the RRC resume configuration in the RRC resume message at 302. After the UE receives the RRC resume message, the UE stops all idle / inactive mode related activities including cell reselection. As explainedin greater detail below, example implementations of the present disclosure provide a solution that allows handover (or cell switch) during an RRC resume procedure.

[0084] More particularly, example implementations of the present disclosure provide a solution to the problem of delay in handover when a UE 110 happens to transition from RRC inactive to RRC connected at the cell edge. This problem is illustrated in FIG. 4, is which is a line chart 400 of signal conditions of a first cell 402 (cell 1, source cell) and a second cell 404 (cell 2, target cell) for a UE performing an RRC resume followed by a handover. In FIG. 4, T1 represents the instance where the UE initiates an RRC resume procedure via either a mobile originated (MO) or mobile terminated (MT) connection to the first cell.

[0085] At time T2, the signal condition of the first cell 402 and second cell 404 are at the same level, with the signal condition of the first cell decreasing as the UE approaches the edge of the first cell. If one assumes handover is to be triggered when the reference signal received power (RSRP) of the first cell (RSRPs) equals that of the second cell (RSRPt), handover should start at this point (without considering time to trigger). However, handover cannot be performed yet since the UE 110 is in the middle of an RRC resume procedure.

[0086] At T3, the UE has successfully completed the RRC resume procedure with the first cell 402, and the UE is now in connected mode. At this point, the difference between the signal condition of the first cell and that of the second cell 404 has increased, with the signal condition of the second cell overpowering the that of the first cell. However, the handover still cannot be executed as the gNB 206 of the first cell needs measurements from the UE to trigger the handover. The gNB can only start the handover process once the gNB receives a suitable measurement report from the UE, which is shown at T4. However, at this window (until T5), the difference between the source and target RF condition is already too large which increases the chances of handover failure (HOF) and / or radio link failure (RLF).

[0087] As shown in FIG. 4, then, the time period T2 to T4 represents a delay before the handover procedure can commence. In this regard, the time period T2 to T3 represents the delay due to the RRC resume procedure, and the time period T3 to T4 represents the delay due to measurement reporting. But in the illustrated scenario, thetime period T4 to T5 may be a critical period to perform handover since the signal condition in the first cell 402 is already poor and with strong interference from the second cell 404.

[0088] When a UE 110 initiates a connection resume request to its current camped cell (e.g., the first cell 402) and then reselects to an adjacent cell (e.g., the second cell 404), the UE stops monitoring the physical downlink control channel (PDCCH) (providing the information to receive the RRC resume message) from the previous cell. The UE starts listening to the PDCCH from the new cell. The UE therefore cannot receive the RRC resume message from the first cell. This is shown in FIG. 5, which illustrates a signaling chart 500 of the RRC resume procedure that is unsuccessful when the UE performs a cell reselection before the RRC resume procedure is completed.

[0089] As shown, the UE 110 continues to perform cell re-selection measurement and evaluation after the UE sends the RRC resume request to its camped cell (of source gNB 206A) at step 301. The UE will then miss RRC setup in case re-selection happens, and the RRC resume at step 302 will fail. As a result, the UE at step 503 transitions to RRC idle if the initial connection resume (towards the camped cell) fails. To gain connection, UE must start from scratch and perform an RRC setup in the target cell (of target gNB 206B), as shown at steps 504, 505 and 505. Additionally, as shown in FIG. 6, cell reselection while performing RRC resume may introduce delays. If the UE instead waits with reselection after the UE sends the RRC resume request, the UE may still risk missing the RRC setup message if the UE has moved out of coverage of its camped cell.

[0090] In summary, considering the UE state, two mobility procedures exist, namely, cell reselection for idle / inactive UEs, and handover for connected UEs. These mobility procedures may not work optimally, however, especially for UEs transitioning from RRC inactive to RRC connected. Performing cell reselection (FIG. 6) at this transition period may introduce delay in resuming the RRC while waiting for a handover after connection resume may result in handover delay and ultimately, failure (FIG. 4).

[0091] In view of the foregoing, example implementations of the present disclosure provide a solution that enables handover (cell switching) during the RRC resume procedure. The solution of some example implementations is a hybrid of handover and cell reselection in which handover may be triggered based on idle / inactive measurementsused for the cell reselection, and the handover may be carried out similar to Layer 3 (L3) handover. Some example implementations rely on measurements performed by a UE 110 in RRC idle / inactive, and leverage UE context stored by a source cell (source gNB 206A) to successfully move the UE from the source cell to a better cell (of a target gNB 206B) during a RRC resume procedure.

[0092] Due to potential added delay, the solution of some example implementations may particularly benefit UEs 110 near the edge / border of its camped cell, where the signal strength / quality of the camped cell is observably or expectedly worse than neighboring cell(s). A high-level illustration of the solution is shown in FIG. 7, which is a line chart 700 of signal conditions for the first and second cells of FIG. 4, in which the UE performs handover during RRC resume, during the time period T2 to T4.

[0093] Some example implementations of the present disclosure provide a source gNB 206A (a source access node) that may send a RRC suspend message to a UE 110 to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended. The RRC suspend message also includes an idle / inactive measurement (IM) reporting configuration. Then at some later time, the UE detect a connection request and perform a random access channel (RACH) procedure in which the UE may send an RRC resume request to the source gNB to resume the RRC connection. The UE may also send an IM report to the source gNB in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled.

[0094] The source gNB 206A may make a determination to trigger a handover to a target gNB 206B based on an evaluation of the IM report. The source gNB may also send a handover request message to the target gNB that includes an indication that the handover is for the UE to resume the RRC connection with the target access node. The target gNB may perform an admission control based on the handover request message, and send a handover response message to the source gNB that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE 110 to perform the handover to the target access node. The source gNB may then send an RRC resume message to the UE that includes the handover configuration for the UE to perform the handover, enter an RRC connected state and resume the RRC connection with the target gNB. This may include the UE sending (and the target gNB receiving) an RRCresume complete message to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0095] In some other example implementations, the UE 110 may perform a RACH- based handover with the target gNB 206B. In some of these other example implementations, the source gNB 206A may send an RRC resume message to the UE 110 that includes a handover configuration and an indication to terminate the RACH procedure of the UE with the source gNB. The UE may then terminate the RACH procedure and carry out a new RACH procedure towards the target gNB to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node.

[0096] To further illustrate example implementations of the present disclosure, FIGS. 8A and 8B illustrate a signaling chart 800 of procedures for handover during a RRC resume, according to some example implementations. The network determines to send a UE 110 in RRC connected to RRC inactive, the source gNB 206A at step 801 sends an RRC suspend message. The source gNB also provides an IM reporting configuration to the UE, including condition(s) / event(s) the UE can use to decide if it should / should not report IM during RRC resume. The UE at step 802 performs idle / inactive measurements while in inactive mode, and the UE at step 803 detects an MO / MT connection request.

[0097] The UE 110 at step 804 performs an evaluation of the IM reporting configuration to determine whether to send or not send the measurements done during idle / inactive mode based on condition(s) / event(s). In this regard, FIG. 9 is a flowchart 900 of a process for evaluation of an IM reporting configuration performed by the UE, according to some example implementations. As shown at blocks 902 and 904, the UE may detect a MO / MT connection request, and determine whether a condition for IM reporting is met. For example, a condition can be based on the quality of the camped cell, i.e., camped cell measurements. UE may compare the camped cell versus a threshold or camped cell versus other neighbour cells on the same or neighbour frequencies.

[0098] As shown in block 906, the UE 110 may also determine whether a delay tolerance for the MO / MT connection request is met. In this regard, in some examples, the UE may also check a delay tolerance of a service requested by the MO / MT connection request before deciding to send the measurements to the source gNB 206A. For example,URLLC related traffic may have lower delay tolerance than eMBB related traffic. In one example, the UE may be provided the explicit indication / configuration of scenarios (e.g., delay tolerance) in which the UE may trigger sending the measurements. These conditions may be configured (e.g., during the RRC connected state) or predefined by 3 GPP. The UE may indicate its capability to support such condition / event-based measurement reporting during idle / inactive mode.

[0099] Based on the IM evaluation, the UE 110 may determine to send a regular or dedicated special preamble to the source gNB. As shown at block 908, the UE may determine to send a regular preamble when the condition for IM reporting or the delay tolerance is not met. Otherwise, the UE may determine to send a dedicated preamble when both the condition for IM reporting and the delay tolerance are met, as shown at block 910. In some examples, the dedicated preamble may be selected from a fix set of pre-assigned preambles that when received by the source gNB 206A indicate that the UE wants to send IMs. Another option is to send the regular preamble that also includes an indication that the UE requests to send IMs.

[0100] Returning to FIG. 8A, the UE 110 at step 805 performs a RACH procedure with the source gNB 206A. The UE at step 805.1 sends the regular or dedicated preamble (based on the IM evaluation) to the source gNB. Depending on whether the source gNB receives a regular or dedicated preamble, the source gNB at step 805.2 responds accordingly. If the source gNB determines based on the dedicated preamble that the UE wants to send IMs, the source gNB responds with a TA, an UL grant for a message (msg3) on the physical uplink shared channel (PUS CH), another UL grant for the IM reporting, and temporary C-RNTI. The UE then at step 805.3 sends an RRC resume request to the source gNB. If the UE received an additional UL grant for IM reporting, the UE at step 805.4 sends an IM report to the source gNB. Alternatively, in some examples, the UE may evaluate its own idle / inactive measurements and decide if handover is needed based on the configuration. In some of these other examples, the UE may just report the best target cell to the network instead of reporting the IMs.

[0101] As shown in FIG. 8B, the source gNB 206A at step 806 performs an evaluation of the IM report from the UE 110. FIG. 10 is a flowchart 1000 of a process for evaluation of an IM report performed by a source radio access node, according to someexample implementations. As shown at blocks 1002 and 1004, the source gNB may receive an IM report including idle / inactive measurements, and determine if a handover condition is fulfilled. One example of a suitable handover condition may be similar to event A3 in RRC connected mode where the source gNB checks if RSRP or reference signal received quality (RSRQ) of the serving cell of the source gNB is “offset” worse than RSRP / RSRQ of a cell of a target gNB 206B.

[0102] If the handover condition is not fulfilled, the source gNB 206A may send a RRC resume message (msg4) to the UE for the RRC resume without handover, as shown at block 1006. Otherwise, if the handover condition is fulfilled, the source gNB may initiate a handover request to the target gNB 206B, as shown at block 1008. And as explained below, if the target gNB acknowledges the handover request, the source gNB may send a RRC resume message to the UE with a handover configuration for handover to the target gNB, as shown at blocks 1010 and 1012.

[0103] Returning to FIG. 8B, when the handover condition is met, the source gNB 206A at step 807 sends a handover request message to the target gNB 206B. Similar to a regular handover when the UE 110 is in RRC connected, the handover request message includes the UE context. Note that in case the UE initiates RRC resume request in a new gNB 206 and not its last serving gNB, the new gNB first performs UE context fetch from the UE’s last serving gNB. But unlike a regular handover request message, the handover request message sent at step 807 message may also include other information such as the TA, allocated UL grant, temporary C-RNTI, or / and an indication that the handover request message is for a UE transitioning from RRC inactive to RRC connected to help the target gNB act accordingly.

[0104] The target gNB 206B at step 808 performs admission control similar to a regular connected mode handover, including determining if resources are available at the target gNB for the UE 110. The target gNB also determines TA and UL grant information for the handover, such as whether the TA value or / and UL grant previously provided by the source gNB 206A to the UE (at step 805.2) may be reused. In this regard, FIG. 11 is a flowchart 1100 of a process for admission control performed by the target gNB, according to some example implementations. As shown at block 1102, the target gNB 206B may receive a handover request from the source gNB 206A. The target gNBdetermines whether resources are available, and if not, the target gNB responds to the source gNB with an admission failure, as shown at blocks 1104 and 1106.

[0105] If the target gNB 206B determines resources are available, the target gNB responds with TA and UL grant information for the handover. If the target gNB determines that the source gNB 206A and the target gNB are co-located and share a UL grant pool, the target gNB may determine TA and UL grant information including an indication for the UE 110 to reuse the TA value and the UL grant from the source gNB, as shown at blocks 1108, 1110 and 1112. In this context, co-location of the gNBs may more particularly refer to co-location of antennas of the gNBs, rather than the gNBs themselves. If the target gNB determines that the source gNB and the target gNB are colocated but do not share a UL grant pool, the target gNB may determine the TA and UL grant information including an indication for the UE to reuse the TA value from the source gNB and use a new UL grant, as shown at blocks 1108, 1110 and 1114.

[0106] In some examples, the target gNB 206B may determine that the source gNB 206A and the target gNB are not co-located but are synchronized, as shown at blocks 1108 and 1116. In some of these examples, if the source gNB and the target gNB share a UL grant pool, the target gNB may determine the TA and UL grant information including an indication for the UE 110 to use a UE-based TA estimation and reuse the UL grant from the source gNB, as shown at blocks 1118 and 1120. On the other hand, if the target gNB determines the that the source gNB and the target gNB do not share a UL grant pool, the target gNB may determine the TA and UL grant information including an indication for the UE to use a UE-based TA estimation and a new UL grant, as shown at block 1118 and 1122. If the source gNB and the target gNB are not co-located or synchronized, the target gNB may respond to the source gNB with an admission failure, as shown at blocks 1108, 1116 and 1106.

[0107] In yet other examples that may be considered for TA information, if the source gNB 206A and the target gNB 206B are not co-located, but the TA value for the target gNB is known, for example, TA = 0 (due to small cell deployment). The target gNB may determine the TA information including an indication to use the known TA value (e.g., TA = 0). If the source gNB and the target gNB are not co-located and are not synchronized, the target gNB may determine TA information that indicates a timingalignment error / offset between the source gNB and the target gNB, for the UE 110 to use UE-based TA estimation to the source gNB. In some examples, the target gNB may not determine any TA information for handover, and the source gNB may instead determine the TA information, such as whether the same TA (as in the source gNB), TA = 0, or UE-based TA may be used for the target gNB.

[0108] Returning to FIG. 8B, the target gNB 206B at step 809 generates and sends a handover response to the source gNB 206A that includes a RRC configuration of the target gNB, and the TA and UL grant information determined by the target gNB. In case of intra-gNB handover, steps 807, 808 and 809 may be skipped.

[0109] Upon receiving the handover response from the target gNB 206B, the source gNB 206A at step 810 generates and sends a RRC resume message (msg4) to the UE 110 that includes an RRC resume configuration for the target gNB. The handover response also includes a handover configuration, which may include information for the UE to access the target gNB (e.g, target cell ID, new C-RNTI, the target gNB security algorithm, etc.). The handover configuration may include, or the RRC resume message may separately include, the TA and UL grant information from the target gNB (e.g., TA value, whether the TA value may be re-used or should be determined by UE-based TA estimation, re-use / new UL grant).

[0110] In some examples, the RRC resume message from the source gNB 206A may also include the RRC resume configuration for the source gNB to be used by the UE 110 if the handover, TA estimation, or other procedure to access the target gNB 206B fails (shown in FIG. 10). Assuming that the source gNB is also still prepared to receive the UE, this will allow the UE to still resume RRC with the source gNB.

[0111] The UE 110 receives the RRC resume message from the source gNB 206A, and the UE at step 811 performs an evaluation of the RRC resume message. FIG. 12 is a flowchart 1200 of a process for evaluation of an RRC resume message performed by a UE, according to some example implementations. As shown at block 1202, the UE receives the RRC resume message (msg4) from the source gNB. If the RRC resume message does not include a handover configuration, the UE may resume the RRC connection with the source gNB, as shown at blocks 1204 and 1206.

[0112] If the RRC resume message from the source gNB 206A includes a handover configuration, the UE 110 may perform a handover and resume with the target gNB 206B. If the RRC resume message includes TA information that indicates for the UE to perform UE -based TA estimation, the UE may also perform TA estimation. In some examples, the UE may estimate a TA value for the target gNB equal to the TA value for the source gNB (received at step 805.2) plus a receive timing difference between the source gNB and the target gNB, which the UE may calculate based on downlink reference signals from both the source gNB and the target gNB. These reference signals may be synchronization signal (SS) / physical broadcast channel (PBCH) blocks (SSBs), channel state information - reference signal (CSI-RS) or the like. In case a timing alignment error between the source gNB and the target gNB is given, the UE may also take that error into account in TA estimation. If the TA estimation fails, or the handover fails, the UE may use the RRC resume configuration for the source gNB (discussed in previous step) to resume the RRC connection with the source gNB, as shown at blocks 1208, 1210 and 1212.

[0113] Again returning to FIG. 8B, upon successful TA-estimation and handover, the UE 110 at step 812 sends an RRC resume complete message to the target gNB 206B. In the event TA estimation / cell switch fails, the UE instead sends the RRC resume complete message to the source gNB 206A. When the target gNB receives the RRC resume complete message, the target gNB at step 813 informs the source gNB about the UE’s successful RRC resumption with the target gNB, and requests that the source gNB release the UE context.

[0114] In some examples, based on the idle / inactive measurements (IM), a beam may also be indicated to the UE 110 to be used. More specifically, beam information, e.g., RS ID (e.g., SSB ID or CSI-RS ID) or transmission configuration indicator (TCI) state ID may be given for the UE to determine a transmit spatial domain filter (UL beam) to be used to transmit the UL transmission (using the given configured grant). Moreover, the beam may be determined by the source gNB 206A / cell and sent to the target gNB 206B / cell in the handover request. The target gNB / cell may confirm / update the beam information in the handover response. Alternatively, a dynamic grant-based solution may be used. The UE may monitor a PDCCH from the target gNB / cell and then transmit theRRC resume complete message on the UL grant received in the PDCCH. The UE may use the beam provided in cell switch configuration to determine the beam to receive PDCCH.

[0115] The procedures described above with reference to the signaling chart 800 in FIGS. 8A and 8B involve a RACH-less connection of the UE 110 towards the target gNB 206B for the handover (cell switch). In other example implementations, the UE may perform another RACH procedure towards the target gNB. In this regard, FIGS. 13A and 13B illustrate a signaling chart 1300 of procedures for a RACH-based handover during a RRC resume, according to some example implementations. As shown in FIGS. 13 A and 13B, the procedures include steps 801-806, as described above.

[0116] When the handover condition is met, the source gNB 206A at step 1307 sends a handover request message to the target gNB 206B. As before, the handover request message includes the UE context. The target gNB at step 1308 performs admission control similar to a regular connected mode handover, including determining if resources are available at the target gNB for the UE 110. The target gNB at step 1309 generates and sends a handover response to the source gNB that includes a RRC configuration of the target gNB.

[0117] The source gNB 206A at step 1310 generates and sends a RRC resume message (msg4) to the UE 110 that includes an RRC resume configuration for the target gNB 206B, as well as a handover configuration (e.g, target cell ID, new C-RNTI, the target gNB security algorithm, etc.). The RRC resume message may also include an indication for the UE to terminate the RACH procedure towards the source gNB.

[0118] In the RACH-based handover, after the UE 110 receives the RRC resume message from the source gNB 206A that includes the handover configuration, the UE at step 1311 determines to perform handover with a RACH procedure towards the target gNB. But the UE has an incomplete RACH procedure with the source gNB (no RRC resume complete message being sent towards the source gNB), and cannot have two ongoing RACH procedures. Based on the indication to terminate the RACH procedure in the RRC resume message, then, the UE may terminate its RACH procedure towards the source gNB, and initiate a new RACH procedure towards the target gNB.

[0119] As shown at step 1312 (including steps 1312.1, 1312.2, 1312.3, 1312.4 and 1312.5) the UE and target gNB may carry out the RACH procedure. And when the target gNB receives the RRC resume complete message from the UE at step 1312.5, the target gNB at step 813 informs the source gNB about the UE’s successful RRC resumption with the target gNB, and requests that the source gNB release the UE context.

[0120] In some examples of either or both the RACH-less or RACH-based handover, the UE 110 may indicate its capability to support handover (cell switch) during RRC resume. Further separate capabilities for RACH-less and RACH-based handover may also be indicated.

[0121] FIG. 14 is a flowchart illustrating various steps in a method 1400 performed by a source access node, according to various example implementations. The method includes sending at block 1402 a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration. The method includes receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, as shown at block 1404. The method includes making a determination to trigger a handover based on an evaluation of the IM report, as shown at block 1406. And the method includes sending an RRC resume message to the UE that includes a handover configuration for the UE to perform the handover, enter an RRC connected state and resume the RRC connection with a target access node, as shown at block 1408.

[0122] In some examples, the IM report is received from the UE at block 1404 during a random access channel (RACH) procedure towards the source access node in which an uplink (UL) grant is sent to the UE for the IM report, and the IM report is received from the UE using the UL grant.

[0123] In some examples, the method 1400 further includes receiving a handover response message from the target access node that includes timing advance (TA) and uplink (UL) grant information. In some of these examples, the handover configuration included in the RRC resume message sent to the UE at block 1408 includes the TA and UL grant information.

[0124] In some examples, the IM report is received from the UE at block 1404 during a random access channel (RACH) procedure towards the source access node in which a TA value and a UL grant from the source access node are sent to the UE. In some of these examples, the TA and UL grant information included in the handover response message is determined by the target access node based on the TA value and the UL grant from the source access node.

[0125] In some examples, the TA and UL grant information includes an indication for the UE to reuse the TA value from the source access node or use a UE-based TA estimation, and either reuse the UL grant from the source access node or use a new UL grant, to access the target access node.

[0126] In some examples, the method 1400 further includes sending a handover request message to the target access node based on the RRC resume request and the determination to trigger the handover. In some of these examples, the handover request message includes an indication that the handover is for the UE to resume the RRC connection with the target access node.

[0127] In some examples, the handover request message sent to the target access node at block 1412 includes a UE context. In some of these examples, the method further includes receiving a message from the target access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0128] FIG. 15 is a flowchart illustrating various steps in a method 1500 performed by a user equipment (UE), according to various example implementations. The method includes receiving at block 1502 a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration. The method includes sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request, as shown at block 1504. The method includes sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger ahandover to a target access node, as shown at block 1506. The method includes receiving an RRC resume message from the source access node that includes a handover configuration, as shown at block 1508. And the method includes performing the handover, entering an RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration, as shown at block 1510.

[0129] In some examples, the IM report is sent to the source access node at block 1506 during a random access channel (RACH) procedure towards the source access node in which an uplink (UL) grant is received by the UE for the IM report, and the IM report is sent to the source access node using the UL grant.

[0130] In some examples, the handover configuration includes timing advance (TA) and uplink (UL) grant information that includes an indication for the UE to reuse a TA value from the source access node or use a UE-based TA estimation, and either reuse a UL grant from the source access node or use a new UL grant, to access the target access node. In some of these examples, the handover is performed at block 1510 based on the TA and UL grant information.

[0131] In some examples, the handover configuration includes the indication for the UE to use the UE-based TA estimation. The method further includes performing the UE- based TA estimation to determine a UE-based TA value for the target access node. In some of these examples, the handover is performed using the UE-based TA value and either reusing the UL grant or using the new UL grant.

[0132] FIGS. 16A - 16F are flowcharts illustrating various steps in a method 1600 performed by a target access node, according to various example implementations. The method includes receiving a handover request message from a source access node to request a handover of a user equipment (UE) from a source access node in connection with an RRC resume request from the UE in an RRC inactive mode, the handover request message including an indication that the handover is for the UE to resume an RRC connection with the target access node, as shown at block 1602 of FIG. 16A. The method includes performing an admission control based on the handover request message, as shown at block 1604. Based on the admission control, the method includes sending a handover response message to the source access node that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE to perform thehandover to the target access node, as shown at block 1606. And the method includes receiving an RRC resume complete message from the UE based on an RRC resume message from the source access node to the UE that includes the handover configuration, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state, as shown at block 1608

[0133] In some examples, the handover request message includes a TA value and a UL grant from the source access node. In some of these examples, performing the admission control at block 1604 includes determining the TA and UL grant information based on the TA value and the UL grant from the source access node, as shown at block 1610 of FIG. 16B.

[0134] In some examples, determining the TA and UL grant information at block 1610 includes making a determination that the source access node and the target access node are co-located and share a UL grant pool, as shown at block 1612 of FIG. 16C. And based on the determination, determining the TA and UL grant information inclues determining the TA and UL grant information including an indication for the UE to reuse the TA value and the UL grant from the source access node, as shown at block 1614.

[0135] In some examples, determining the TA and UL grant information at block 1610 includes making a determination that the source access node and the target access node are co-located but do not share a UL grant pool, as shown at block 1616 of FIG. 16D. And based on the determination, determining the TA and UL grant information includes determining the TA and UL grant information including an indication for the UE to reuse the TA value from the source access node and use a new UL grant, as shown at block 1618.

[0136] In some examples, determining the TA and UL grant information at block 1610 includes making a determination that the source access node and the target access node are not co-located but are synchronized, and that the source access node and the target access node share a UL grant pool, as shown at block 1620 of FIG. 16E. And based on the determination determining the TA and UL grant information includes determining the TA and UL grant information including an indication for the UE to use a UE-basedTA estimation and reuse the UL grant from the source access node, as shown at block1622

[0137] In some examples, determining the TA and UL grant information at block 1610 includes making a determination that the source access node and the target access node are not co-located but are synchronized, and that the source access node and the target access node do not share a UL grant pool, as shown at block 1624 of FIG. 16F. And based on the determination, determining the TA and UL grant information includes determining the TA and UL grant information including an indication for the UE to use a UE-based TA estimation and a new UL grant, as shown at block 1626.

[0138] In some examples, the handover request message received from the source access node at block 1602 includes a UE context. In some of these examples, the method 1600 further includes sending a message to the source access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0139] FIG. 17 is a flowchart illustrating various steps in a method 1700 according to various example implementations. The method includes sending at block 1702 a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration. The method includes receiving an IM report from the UE in connection with an RRC resume request of a random access channel (RACH) procedure, and when a reporting event of the IM reporting configuration is fulfilled, as shown at block 1704 of FIG. 17A. The method includes making a determination to trigger a handover based on an evaluation of the IM report, as shown at block 17O6.Based on the RRC resume request and the determination, the method includes sending a handover request message to a target access node, as shown at block 1708. And the method includes sending an RRC resume message to the UE that includes a handover configuration and an indication to terminate the RACH procedure, for the UE to terminate the RACH procedure and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node, as shown at block 1710.

[0140] In some examples, the IM report is received from the UE at block 1704 during the RACH procedure in which an uplink (UL) grant is sent to the UE for the IM report, and the IM report is received from the UE using the UL grant.

[0141] In some examples, the method is performed by a source access node, and the handover request message sent to the target access node at block 1708 includes a UE context. In some of these examples, the method further includes receiving a message from the target access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0142] FIG. 18A and 18B are flowcharts illustrating various steps in a method 1800 according to various example implementations. The method includes receiving at block 1802 a radio resource control (RRC) suspend message from a source access node to trigger a transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration. The method includes initiating a random access channel (RACH) procedure towards the source access node, as shown at block 1804 of FIG. 18A. The method includes sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request, as shown at block 1806.

[0143] As also shown, the method 1800 includes sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node, as shown at block 1808. The method includes receiving an RRC resume message from the source access node that includes a handover configuration and an indication to terminate the RACH procedure, as shown at block 1810. The method includes terminating the RACH procedure towards the source access node, as shown at block 1812. And the method includes carrying out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration, as shown at block 1814.

[0144] In some examples, the IM report is sent to the source access node at block 1808 during the RACH procedure in which an uplink (UL) grant is received for the IM report, and the IM report is sent to the source access node using the UL grant.

[0145] In some examples, carrying out the new RACH procedure at block 1814 includes sending a random access preamble towards the target access node, as shown at block 1816 FIG. 18B. In some of these examples, carrying out the new RACH procedure also includes receiving a timing advance (TA) value and an uplink (UL) grant from the target access node, and accessing the target access node using the TA value and the UL grant, as shown at blocks 1818 and 1820.

[0146] FIGS. 19A and 19B are flowcharts illustrating various steps in a method 1900 according to various example implementations. The method includes receiving a handover request message from a source access node to request a handover of a user equipment (UE) from the source access node in connection with an RRC resume request from the UE in an RRC inactive state, the handover request message including an indication that the handover is for the UE to resume an RRC connection with a target access node, as shown at block 1902 of FIG. 19A. The method includes performing admission control to establish an RRC connection with the UE, as shown at block 1904. And the method includes carrying out a random access channel (RACH) procedure with the UE during which an RRC resume complete message is received from the UE based on an RRC resume message of an earlier RACH procedure from the source access node to the UE that includes the handover configuration and an indication to terminate the earlier RACH procedure, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state, as shown at block 1906.

[0147] In some examples, carrying out the RACH procedure at block 1908 includes receiving a random access preamble from the UE, as shown at block 1910 of FIG. 19B. In some of these examples, carrying out the RACH procedure also includes determining a timing advance (TA) value and an uplink (UL) grant, and sending a random access response to the UE that includes the TA value and the UL grant for the UE to access the target access node, as shown at blocks 1912 and 1914.

[0148] In some examples, the handover request message received from the source access node at block 1902 includes a UE context. In some of these examples, the method further includes sending a message to the source access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0149] FIG. 20 is a flowchart illustrating various steps in a method 2000 performed by a user equipment (UE), according to various example implementations. The method includes receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration, as shown at block 2002. The method includes performing an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request, as shown at block 2004.

[0150] The method 2000 includes sending a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation, as shown at block 2006. The method includes carrying out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node, as shown at block 2008. And the method includes receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node, as shown at block 2010.

[0151] In some examples, the random access preamble is a dedicated random access preamble that indicates the IM report is to be sent.

[0152] In some examples, performing the evaluation of the IM reporting configuration at block 2004 includes determining a reporting event for the IM report is fulfilled based on at least idle / inactive measurements of at least the source access node.

[0153] In some examples, the detected connection request is for a connection, and performing the evaluation of the IM reporting configuration at block 2004 further includes determining a delay tolerance for the connection is satisfied.

[0154] In some examples, the configuration in the RRC resume message is a configuration for the source access node. In some of these examples, the method 2000 further includes entering the RRC connected state, and resuming the RRC connection with the source access node based on the configuration.

[0155] FIG. 21 is a flowchart illustrating various steps in a method 2100 performed by a source access node, according to various example implementations. The method includes sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration, as shown at block 2102. The method includes receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, as shown at block 2104. The method includes performing at block 2106 an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation. And based on the RRC resume request and the evaluation, the method includes sending an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node, as shown at block 2108.

[0156] In some examples, the method 2100 further includes receiving the RRC resume request to resume the RRC connection based on a detected connection request at the UE for a connection. In some of these examples, the IM report is received at block 2104 when the reporting event is fulfilled, and a delay tolerance for the connection is satisfied.

[0157] In some examples, performing the evaluation of the IM report at block 2106 includes determining a condition to trigger the handover is fulfilled based on idle / inactive measurements of the source access node and the target access node.

[0158] In some examples, the configuration in the RRC resume message is a configuration for the source access node, and the RRC resume message is sent at block 2108 for the UE to enter the RRC connected state, and resume the RRC connection with the source access node based on the configuration.

[0159] In some examples, the configuration in the RRC resume message is a handover configuration, and the RRC resume message is sent at block 2108 for the UE to perform the handover, enter the RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0160] According to example implementations of the present disclosure, a telecommunications system 100 or PLMN 102, and its components such as a UE 110, CN 106, RAN 108, and / or radio access node 202, may be implemented by various means. Means for implementing the system and its components may include hardware, firmware, software, or combinations thereof. In some examples, one or more apparatuses may be configured to function as or otherwise implement the system and its components shown and described herein. In examples involving more than one apparatus, the respective apparatuses may be connected to or otherwise in communication with one another in a number of different manners, such as directly or indirectly via a wired or wireless network or the like.

[0161] According to some example implementations, at least some of the method 1400 described with respect to FIGS. 14 may be carried out by an apparatus comprising means for performing functions corresponding steps of the method. Similarly, at least some of the method 1500 described with respect to FIG. 15 may be carried out by an apparatus comprising means for performing functions corresponding steps of the method. And each method 1600, 1700, 1800, 1900, 2000 and 2100 of respective ones of FIGS. 16A-16F, FIG. 17, FIGS. 18 A and 18B, FIGS. 19A and 19B, FIG. 20, FIG. 21 and FIG. 22 may be carried out by an apparatus comprising means for performing functions corresponding steps of the method. Examples of a suitable apparatus may include a gNB (e.g., gNB-DU, gNB-CU), ng-eNB or any suitable apparatus, such as a server, host or node. Other examples of a suitable apparatus may include a user equipment, user device, user terminal or the like.

[0162] FIG. 22 illustrates an apparatus 2200 in which means for performing various functions includes hardware, alone or under direction of one or more computer programs from a computer-readable storage medium or other memory, such as computer memory, according to some example implementations of the present disclosure. The apparatus may include one or more of each of a number of components such as, for example, processing circuitry 2202 connected to computer-readable storage medium or other memory 2204.

[0163] The processing circuitry 2202 may be composed of one or more processors alone or in combination with one or more computer-readable storage media. The processing circuitry is generally any piece of computer hardware that is capable of processing information such as, for example, data, computer programs and / or other suitable electronic information. The processing circuitry is composed of a collection of electronic circuits some of which may be packaged as an integrated circuit or multiple interconnected integrated circuits (an integrated circuit at times more commonly referred to as a “chip”). The processing circuitry may be configured to execute computer programs, which may be stored onboard the processing circuitry or otherwise stored in the memory 2204 (of the same or another apparatus).

[0164] The processing circuitry 2202 may be a number of processors, a multi-core processor or some other type of processor, depending on the particular implementation. Further, the processing circuitry may be implemented using a number of heterogeneous processor systems in which a main processor is present with one or more secondary processors on a single chip. As another illustrative example, the processing circuitry may be a symmetric multi-processor system containing multiple processors of the same type. In yet another example, the processing circuitry may be embodied as or otherwise include one or more ASICs, FPGAs or the like. Thus, although the processing circuitry may be capable of executing a computer program to perform one or more functions, the processing circuitry of various examples may be capable of performing one or more functions without the aid of a computer program. In either instance, the processing circuitry may be appropriately programmed to perform functions or operations according to example implementations of the present disclosure.

[0165] The memory 2204 is generally any piece of computer hardware that is capable of storing information such as, for example, data, computer programs, instructions 2206(e.g., computer-readable program code) and / or other suitable information either on a temporary basis and / or a permanent basis. The memory may include volatile and / or nonvolatile memory, and may be fixed or removable. Examples of suitable memory include recording media, random access memory (RAM), read-only memory (ROM), a hard drive, a flash memory, a thumb drive, a removable computer diskette, an optical disk or some combination thereof.

[0166] The memory 2204 is a non-transitory device capable of storing information. One example of a suitable memory is a computer-readable storage medium, which is distinguishable from a computer-readable transmission medium capable of carrying information from one location to another. Examples of suitable computer-readable transmission media comprise electronic carrier signals, telecommunications signals, software distribution packages, or some combination thereof. As used herein, the term “non-transitory” is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM versus ROM). A computer-readable medium as described herein generally refers to a computer-readable storage medium or computer-readable transmission medium. A computer-readable medium is any entity or device capable in which information, such as one or more computer programs or portions thereof, may be stored and carried.

[0167] In addition to the memory 2204 (e.g., computer-readable storage medium), the processing circuitry 2202 may also be connected to one or more interfaces for displaying, transmitting and / or receiving information. The interfaces may include a communications interface 2208 and / or one or more user interfaces. The communications interface may be configured to transmit and / or receive information, such as to and / or from other apparatus(es), network(s) or the like. The communications interface may be configured to transmit and / or receive information by physical (wired) and / or wireless communications links. Examples of suitable communication interfaces include a network interface controller (NIC), wireless NIC (WNIC) or the like.

[0168] The user interfaces may include a display 2210 and / or one or more user input interfaces 2212. The display may be configured to present or otherwise display information to a user, suitable examples of which include a liquid crystal display (LCD), light-emitting diode (LED) display, organic LED (OLED) display, active-matrix OLED(AMOLED) or the like. The user input interfaces may be wired or wireless, and may be configured to receive information from a user into the apparatus, such as for processing, storage and / or display. Suitable examples of user input interfaces include a microphone, image or video capture device, keyboard or keypad, joystick, touch-sensitive surface (separate from or integrated into a touchscreen), biometric sensor or the like. The user interfaces may further include one or more interfaces for communicating with peripherals such as printers, scanners or the like.

[0169] Execution of the instructions 2206 by the processing circuitry 2202, or storage of the instructions in the memory 2204, supports combinations of operations for implementing example implementations of the present disclosure. In this manner, an apparatus 2200 may comprise at least one processing circuitry and at least one memory coupled to the at least one processing circuitry, where the at least one processing circuitry is configured to execute instructions stored in the at least one memory. It will also be understood that one or more functions, and combinations of functions, may be implemented by special purpose hardware-based computer systems and / or processing circuitry which perform the specified functions, or combinations of special purpose hardware and program code instructions.

[0170] Some example implementations of the present disclosure may also be carried out in the form of a computer process defined by one or more computer programs or portions thereof. Example implementations of the present disclosure may be carried out by executing at least one portion of a computer program comprising instructions. The computer program may be in source code form, object code form, or in some intermediate form. The computer program may be stored in a computer-readable medium that is readable by a computer, processing circuitry or other suitable apparatus. As indicated above, for example, the computer program may be stored in a memory, such as a computer-readable storage medium. Additionally or alternatively, for example, the computer program may be stored in a computer-readable transmission medium. The coding of software for carrying out example implementations of the present disclosure is well within the scope of a person of ordinary skill in the art.

[0171] As will be appreciated, any suitable instructions may be loaded onto a computer, a processing circuitry or other programmable apparatus from a memory or acomputer-readable medium (e.g., computer-readable storage medium, computer-readable transmission medium) to produce a particular machine, such that the particular machine becomes a means for implementing the functions specified herein. The instructions may also be stored in a computer-readable medium that can direct a computer, a processing circuitry or other programmable apparatus to function in a particular manner to thereby generate a particular machine or particular article of manufacture. In some examples, the instructions stored in the computer-readable medium may produce an article of manufacture, where the article of manufacture becomes a means for implementing functions described herein. The instructions may be retrieved from a computer-readable medium and loaded into a computer, processing circuitry or other programmable apparatus to configure the computer, processing circuitry or other programmable apparatus to execute operations to be performed on or by the computer, processing circuitry or other programmable apparatus.

[0172] Retrieval, loading and execution of instructions comprising program code instructions may be performed sequentially such that one instruction is retrieved, loaded and executed at a time. In some example implementations, retrieval, loading and / or execution may be performed in parallel such that multiple instructions are retrieved, loaded, and / or executed together. Execution of the program code instructions may produce a computer-implemented process such that the instructions executed by the computer, processing circuitry or other programmable apparatus provide operations for implementing functions described herein.

[0173] As explained above and reiterated below, the present disclosure includes, without limitation, the following example implementations.

[0174] Clause 15. A method performed by a source access node, the method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; making a determination to trigger a handover based on an evaluation of the IM report; and sending an RRC resume message to the UE that includes a handover configurationfor the UE to perform the handover, enter an RRC connected state and resume the RRC connection with a target access node.

[0175] Clause 16. The method of clause 15, wherein the IM report is received from the UE during a random access channel (RACH) procedure towards the source access node in which an uplink (UL) grant is sent to the UE for the IM report, and the IM report is received from the UE using the UL grant.

[0176] Clause 17. The method of clause 15 or clause 16, wherein the method further comprises receiving a handover response message from the target access node that includes timing advance (TA) and uplink (UL) grant information, and wherein the handover configuration included in the RRC resume message sent to the UE includes the TA and UL grant information.

[0177] Clause 18. The method of clause 17, wherein the IM report is received from the UE during a random access channel (RACH) procedure towards the source access node in which a TA value and a UL grant from the source access node are sent to the UE, and wherein the TA and UL grant information included in the handover response message is determined by the target access node based on the TA value and the UL grant from the source access node.

[0178] Clause 19. The method of clause 18, wherein the TA and UL grant information includes an indication for the UE to reuse the TA value from the source access node or use a UE-based TA estimation, and either reuse the UL grant from the source access node or use a new UL grant, to access the target access node.

[0179] Clause 20. The method of any of clauses 15 to 19, wherein the method further comprises sending a handover request message to the target access node based on the RRC resume request and the determination to trigger the handover, wherein the handover request message includes an indication that the handover is for the UE to resume the RRC connection with the target access node.

[0180] Clause 21. The method of clause 20, wherein the handover request message sent to the target access node includes a UE context, and wherein the method further comprises receiving a message from the target access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0181] Clause 22. An apparatus implemented by a source access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least perform the method of any one of clauses 15 to 21.

[0182] Clause 23. An apparatus comprising means for performing the method of any of clauses 15 to 21.

[0183] Clause 24. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 15 to 21.

[0184] Clause 25. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 15 to 21.

[0185] Clause 26. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 15 to 21.

[0186] Clause 34. A method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; receiving an RRC resume message from the source access node that includes a handover configuration; and performing the handover, entering an RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration.

[0187] Clause 35. The method of clause 34, wherein the IM report is sent to the source access node during a random access channel (RACH) procedure towards thesource access node in which an uplink (UL) grant is received by the UE for the IM report, and the IM report is sent to the source access node using the UL grant.

[0188] Clause 36. The method of clause 34 or clause 35, wherein the handover configuration includes timing advance (TA) and uplink (UL) grant information that includes an indication for the UE to reuse a TA value from the source access node or use a UE-based TA estimation, and either reuse a UL grant from the source access node or use a new UL grant, to access the target access node, and wherein the handover is performed based on the TA and UL grant information.

[0189] Clause 37. The method of clause 36, wherein the handover configuration includes the indication for the UE to use the UE-based TA estimation, and the method further comprises performing the UE-based TA estimation to determine a UE-based TA value for the target access node, and wherein the handover is performed using the UE- based TA value and either reusing the UL grant or using the new UL grant.

[0190] Clause 38. An apparatus implemented by a user equipment (UE), the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least the method of any one of clauses 34 to 37.

[0191] Clause 39. An apparatus comprising means for performing the method of any of clauses 34 to 37.

[0192] Clause 40. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 34 to 37.

[0193] Clause 41. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 34 to 37.

[0194] Clause 42. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 34 to 37.

[0195] Clause 56. A method performed by a target access node, the method comprising: receiving a handover request message from a source access node to request a handover of a user equipment (UE) from a source access node in connection with anRRC resume request from the UE in an RRC inactive mode, the handover request message including an indication that the handover is for the UE to resume an RRC connection with the target access node; performing an admission control based on the handover request message; and based on the admission control, sending a handover response message to the source access node that includes timing advance (TA) and uplink (UL) grant information for a handover configuration for the UE to perform the handover to the target access node; and receiving an RRC resume complete message from the UE based on an RRC resume message from the source access node to the UE that includes the handover configuration, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0196] Clause 57. The method of clause 56, wherein the handover request message includes a TA value and a UL grant from the source access node, and performing the admission control includes determining the TA and UL grant information based on the TA value and the UL grant from the source access node.

[0197] Clause 58. The method of clause 57, wherein determining the TA and UL grant information comprises: making a determination that the source access node and the target access node are co-located and share a UL grant pool; and based on the determination; determining the TA and UL grant information including an indication for the UE to reuse the TA value and the UL grant from the source access node.

[0198] Clause 59. The method of clause 57 or clause 58, wherein determining the TA and UL grant information comprises: making a determination that the source access node and the target access node are co-located but do not share a UL grant pool; and based on the determination; determining the TA and UL grant information including an indication for the UE to reuse the TA value from the source access node and use a new UL grant.

[0199] Clause 60. The method of any of clauses 57 to 59, wherein determining the TA and UL grant information comprises: making a determination that the source access node and the target access node are not co-located but are synchronized, and that the source access node and the target access node share a UL grant pool; and based on the determination; determining the TA and UL grant information including an indication forthe UE to use a UE-based TA estimation and reuse the UL grant from the source access node.

[0200] Clause 61. The method of any of clauses 57 to 60, wherein determining the TA and UL grant information comprises: making a determination that the source access node and the target access node are not co-located but are synchronized, and that the source access node and the target access node do not share a UL grant pool; and based on the determination; determining the TA and UL grant information including an indication for the UE to use a UE-based TA estimation and a new UL grant.

[0201] Clause 62. The method of any of clauses 56 to 61, wherein the handover request message received from the source access node includes a UE context, and wherein the method further comprises sending a message to the source access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0202] Clause 63. An apparatus implemented by a target access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least the method of any one of clauses 56 to 62.

[0203] Clause 64. An apparatus comprising means for performing the method of any of clauses 56 to 62.

[0204] Clause 65. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 56 to 62.

[0205] Clause 66. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 56 to 62.

[0206] Clause 67. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 56 to 62.

[0207] Clause 73. A method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend messageincluding an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request of a random access channel (RACH) procedure, and when a reporting event of the IM reporting configuration is fulfilled; making a determination to trigger a handover based on an evaluation of the IM report; and based on the RRC resume request and the determination, sending a handover request message to a target access node; and sending an RRC resume message to the UE that includes a handover configuration and an indication to terminate the RACH procedure, for the UE to terminate the RACH procedure and carry out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node.

[0208] Clause 74. The method of clause 73, wherein the IM report is received from the UE during the RACH procedure in which an uplink (UL) grant is sent to the UE for the IM report, and the IM report is received from the UE using the UL grant.

[0209] Clause 75. The method of clause 73 or clause 74, wherein the method is performed by a source access node, and the handover request message sent to the target access node includes a UE context, and wherein the method further comprises receiving a message from the target access node that includes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0210] Clause 76. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least perform the method of any one of clauses 73 to 75.

[0211] Clause 77. An apparatus comprising means for performing the method of any of clauses 73 to 75.

[0212] Clause 78. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 73 to 75.

[0213] Clause 79. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 73 to 75.

[0214] Clause 80. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 73 to 75.

[0215] Clause 86. A method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger a transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; initiating a random access channel (RACH) procedure towards the source access node; sending an RRC resume request to the source access node to resume the RRC connection based on a detected connection request; sending an IM report to the source access node in connection with the RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled, the IM report sent for the source access node to make a determination whether to trigger a handover to a target access node; receiving an RRC resume message from the source access node that includes a handover configuration and an indication to terminate the RACH procedure; terminating the RACH procedure towards the source access node; and carrying out a new RACH procedure towards the target access node to perform the handover, enter an RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0216] Clause 87. The method of clause 86, wherein the IM report is sent to the source access node during the RACH procedure in which an uplink (UL) grant is received for the IM report, and the IM report is sent to the source access node using the UL grant.

[0217] Clause 88. The method of clause 86 or clause 87, wherein carrying out the new RACH procedure comprises: sending a random access preamble towards the target access node; receiving a timing advance (TA) value and an uplink (UL) grant from the target access node; and accessing the target access node using the TA value and the UL grant.

[0218] Clause 89. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least the method of any one of clauses 86 to 88.

[0219] Clause 90. An apparatus comprising means for performing the method of any of clauses 86 to 88.

[0220] Clause 91. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 86 to 88.

[0221] Clause 92. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 86 to 88.

[0222] Clause 93. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 86 to 88.

[0223] Clause 99. A method comprising: receiving a handover request message from a source access node to request a handover of a user equipment (UE) from the source access node in connection with an RRC resume request from the UE in an RRC inactive state, the handover request message including an indication that the handover is for the UE to resume an RRC connection with a target access node; performing admission control to establish an RRC connection with the UE; and carrying out a random access channel (RACH) procedure with the UE during which an RRC resume complete message is received from the UE based on an RRC resume message of an earlier RACH procedure from the source access node to the UE that includes the handover configuration and an indication to terminate the earlier RACH procedure, the RRC resume complete message received to complete the handover of the UE and resume the RRC connection with the UE in an RRC connected state.

[0224] Clause 100. The method of clause 99, wherein carrying out the RACH procedure comprises: receiving a random access preamble from the UE; determining a timing advance (TA) value and an uplink (UE) grant; and sending a random access response to the UE that includes the TA value and the UL grant for the UE to access the target access node.

[0225] Clause 101. The method of clause 99 or clause 100, wherein the handover request message received from the source access node includes a UE context, and wherein the method further comprises sending a message to the source access node thatincludes a notification that the RRC connection has been resumed, and a request for the source access node to release the UE context.

[0226] Clause 102. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least perform the method of any one of clauses 99 to 101.

[0227] Clause 103. An apparatus comprising means for performing the method of any of clauses 99 to 101.

[0228] Clause 104. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 99 to 101.

[0229] Clause 105. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 99 to 101.

[0230] Clause 106. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 99 to 101.

[0231] Clause 120. A method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; performing an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request; sending a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; carrying out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRCconnection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0232] Clause 121. The method of clause 120, wherein the random access preamble is a dedicated random access preamble that indicates the IM report is to be sent.

[0233] Clause 122. The method of clause 120 or clause 121, wherein performing the evaluation of the IM reporting configuration includes determining a reporting event for the IM report is fulfilled based on at least idle / inactive measurements of at least the source access node.

[0234] Clause 123. The method of clause 122, wherein determining the reporting event for the IM report is fulfilled includes determining the reporting event for the IM report is fulfilled based on a comparison of the idle / inactive measurements of the source access node and corresponding idle / inactive measurements of the target access node.

[0235] Clause 124. The method of clause 122 or clause 123, wherein the detected connection request is for a connection, and performing the evaluation of the IM reporting configuration further includes determining a delay tolerance for the connection is satisfied.

[0236] Clause 125. The method of any of clauses 122 to 124, wherein the configuration in the RRC resume message is a configuration for the source access node, and the method further comprises entering the RRC connected state, and resuming the RRC connection with the source access node based on the configuration.

[0237] Clause 126. The method of any of clauses 122 to 125, wherein the configuration in the RRC resume message is a handover configuration, and the method further comprises to performing the handover, entering the RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration.

[0238] Clause 127. An apparatus implemented by a user equipment (UE), the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least perform the method of any one of clauses 120 to 126.

[0239] Clause 128. An apparatus comprising means for performing the method of any of clauses 120 to 126.

[0240] Clause 129. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 120 to 126.

[0241] Clause 130. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 120 to 126.

[0242] Clause 131. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 120 to 126.

[0243] Clause 141. A method performed by a source access node, the method comprising: sending a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; performing an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, sending an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

[0244] Clause 142. The method of clause 141, wherein the method further comprises receiving the RRC resume request to resume the RRC connection based on a detected connection request at the UE for a connection, and wherein the IM report is received when the reporting event is fulfilled, and a delay tolerance for the connection is satisfied.

[0245] Clause 143. The method of clause 142, wherein performing the evaluation of the IM report includes determining a condition to trigger the handover is fulfilled based on idle / inactive measurements of the source access node and the target access node.

[0246] Clause 144. The method of clause 142 or clause 143, wherein the configuration in the RRC resume message is a configuration for the source access node, and the RRC resume message is sent for the UE to enter the RRC connected state, and resume the RRC connection with the source access node based on the configuration.

[0247] Clause 145. The method of any of clauses 142 to 144, wherein the configuration in the RRC resume message is a handover configuration, and the RRC resume message is sent for the UE to perform the handover, enter the RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

[0248] Clause 146. An apparatus implemented by a source access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least perform the method of any one of clauses 141 to 145.

[0249] Clause 147. An apparatus comprising means for performing the method of any of clauses 141 to 145.

[0250] Clause 148. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 141 to 145.

[0251] Clause 149. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 141 to 145.

[0252] Clause 150. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 141 to 145.

[0253] Many modifications and other implementations of the disclosure set forth herein will come to mind to one skilled in the art to which the disclosure pertains having the benefit of the teachings presented in the foregoing description and the associated figures. Therefore, it is to be understood that the disclosure is not to be limited to the specific implementations disclosed and that modifications and other implementations are intended to be included within the scope of the appended claims. Moreover, although theforegoing description and the associated figures describe example implementations in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative implementations without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS:

1. An apparatus implemented by a user equipment (UE), the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: receive a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; perform an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request; send a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; carry out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and receive an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

2. The apparatus of claim 1, wherein the random access preamble is a dedicated random access preamble that indicates the IM report is to be sent.

3. The apparatus of claim 1 or 2, wherein the apparatus caused to perform the evaluation of the IM reporting configuration includes the apparatus caused to determine a reporting event for the IM report is fulfilled based on at least idle / inactive measurements of at least the source access node.

4. The apparatus of claim 3, wherein the apparatus is caused to determine the reporting event for the IM report is fulfilled based on a comparison of the idle / inactive measurements of the source access node and corresponding idle / inactive measurements of the target access node.

5. The apparatus of claim 3 or 4, wherein the detected connection request is for a connection, and the apparatus caused to perform the evaluation of the IM reporting configuration further includes the apparatus caused to determine a delay tolerance for the connection is satisfied.

6. The apparatus of any one of claims 3 to 5, wherein the configuration in the RRC resume message is a configuration for the source access node, and the at least one processing circuitry is configured to execute the instructions to cause the apparatus to further enter the RRC connected state, and resuming the RRC connection with the source access node based on the configuration.

7. The apparatus of any one of claims 3 to 6, wherein the configuration in the RRC resume message is a handover configuration, and the at least one processing circuitry is configured to execute the instructions to cause the apparatus to further perform the handover, enter the RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

8. A method performed by a user equipment (UE), the method comprising: receiving a radio resource control (RRC) suspend message from a source access node to trigger the UE to transition to an RRC inactive state in which an RRC connection with the source access node is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; performing an evaluation of the IM reporting configuration to determine to send a IM report to the source access node based on a detected connection request;sending a random access preamble to trigger a random access channel (RACH) procedure towards the source access node for an RRC resume, the random access preamble indicating the IM report is to be sent based on the evaluation; carrying out the RACH procedure during which an RRC resume request message and the IM report are sent to the source access node; and receiving an RRC resume message from the source access node based on an evaluation of the IM report by the source access node, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform a handover, enter the RRC connected state and resume the RRC connection with a target access node.

9. The method of claim 8, wherein the random access preamble is a dedicated random access preamble that indicates the IM report is to be sent.

10. The method of claim 8 or 9, wherein performing the evaluation of the IM reporting configuration includes determining a reporting event for the IM report is fulfilled based on at least idle / inactive measurements of at least the source access node.

11. The method of claim 10, wherein determining the reporting event for the IM report is fulfilled includes determining the reporting event for the IM report is fulfilled based on a comparison of the idle / inactive measurements of the source access node and corresponding idle / inactive measurements of the target access node.

12. The method of claim 10 or 11, wherein the detected connection request is for a connection, and performing the evaluation of the IM reporting configuration further includes determining a delay tolerance for the connection is satisfied.

13. The method of any of claims 10 to 12, wherein the configuration in the RRC resume message is a configuration for the source access node, and the method further comprises entering the RRC connected state, and resuming the RRC connection with the source access node based on the configuration.

14. The method of any of claims 10 to 13, wherein the configuration in the RRC resume message is a handover configuration, and the method further comprises to performing the handover, entering the RRC connected state, and resuming the RRC connection with the target access node based on the handover configuration.

15. An apparatus implemented by a source access node, the apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to at least: send a radio resource control (RRC) suspend message to a user equipment (UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receive an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; perform an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, send an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

16. The apparatus of claim 15, wherein the at least one processing circuitry is configured to execute the instructions to cause the apparatus to further receive the RRC resume request to resume the RRC connection based on a detected connection request at the UE for a connection, and wherein the IM report is received when the reporting event is fulfilled, and a delay tolerance for the connection is satisfied.

17. The apparatus of claim 16, wherein the apparatus caused to perform the evaluation of the IM report includes the apparatus caused to determine a condition to trigger the handover is fulfilled based on idle / inactive measurements of the source access node and the target access node.

18. The apparatus of claim 16 or 17, wherein the configuration in the RRC resume message is a configuration for the source access node, and the RRC resume message is sent for the UE to enter the RRC connected state, and resume the RRC connection with the source access node based on the configuration.

19. The apparatus of any one of claims 16 to 18, wherein the configuration in the RRC resume message is a handover configuration, and the RRC resume message is sent for the UE to perform the handover, enter the RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

20. A method performed by a source access node, the method comprising: sending a radio resource control (RRC) suspend message to a user equipment(UE) to trigger the UE to transition to an RRC inactive state in which an RRC connection is suspended, the RRC suspend message including an idle / inactive measurement (IM) reporting configuration; receiving an IM report from the UE in connection with an RRC resume request, and when a reporting event of the IM reporting configuration is fulfilled; performing an evaluation of the IM report to determine whether to trigger a handover; and based on the RRC resume request and the evaluation, sending an RRC resume message to the UE based on the evaluation, the RRC resume message including a configuration for the UE to enter an RRC connected state and resume the RRC connection with the source access node, or for the UE to perform the handover, enter the RRC connected state and resume the RRC connection with a target access node.

21. The method of claim 20, wherein the method further comprises receiving the RRC resume request to resume the RRC connection based on a detected connection request at the UE for a connection, and wherein the IM report is received when the reporting event is fulfilled, and a delay tolerance for the connection is satisfied.

22. The method of claim 21, wherein performing the evaluation of the IM report includes determining a condition to trigger the handover is fulfilled based on idle / inactive measurements of the source access node and the target access node.

23. The method of claim 21 or 22, wherein the configuration in the RRC resume message is a configuration for the source access node, and the RRC resume message is sent for the UE to enter the RRC connected state, and resume the RRC connection with the source access node based on the configuration.

24. The method of any one of claims 21 to 23, wherein the configuration in the RRC resume message is a handover configuration, and the RRC resume message is sent for the UE to perform the handover, enter the RRC connected state, and resume the RRC connection with the target access node based on the handover configuration.

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