Patent Description:
Radio Resource Control (RRC) is an air interface protocol used in the 3rd generation mobile cellular wireless network protocol Universal Mobile Telecommunications System (UMTS), as well as the 4th generation protocol, Long Term Evolution (LTE). Modifications to RRC are proposed for the 5th generation protocol, New Radio (NR). The Third Generation Partnership Project (3GPP) specifications for UMTS RRC are in Technical Standard (TS) <NUM> V15. <NUM>, and for LTE RRC are in TS <NUM> V15.

<FIG> depicts a state diagram of LTE RRC modes. In LTE, two general RRC modes are defined for a wireless device, or User Equipment (UE): RRC_IDLE and RRC_CONNECTED. Within the RRC_CONNECTED mode, a UE transitions between further RRC states, each having lower power consumption, based on inactivity timers. The RRC_CONNECTED mode states for LTE are CELL-DCH (Dedicated Channel), CELL_FACH (Forward Access Channel), CELL_PCH (Cell Paging Channel) and URA_PCH (UTRAN Registration Area, or URA, Paging Channel). This disclosure focuses on transitions between RRC_CONNECTED and RRC_IDLE modes (and analogous NR RRC transitions), not the RRC_CONNECTED states. Accordingly, the terms RRC mode and RRC state are used interchangeably herein.

In LTE RRC_IDLE state, a UE is known to the core network (CN) or evolved packet core (EPC), and has an IP address, but is not known/tracked by the Radio Access Network (E-UTRAN) and its base stations (evolved Node B or eNB). The UE can receive broadcast/multicast data (e.g., System Information, or SI); monitors a paging channel to detect incoming calls; may perform neighbor cell measurements; and can do cell (re)selection. A UE in RRC_IDLE may be configured by the network for Discontinuous Reception (DRX).

In the LTE RRC_CONNECTED state, the UE is known by the RAN (E-UTRAN/eNB), as well as the core network, and the mobility of the UE is managed by the network. The UE monitors control channels for downlink data, sends channel quality feedback, and may request uplink resources. The RRC messages RRC Release and RRC Connect transition the UE from RRC_CONNECTED to and from RRC_IDLE state.

<FIG> depicts a state diagram of NR RRC states. NR introduces a new RRC state: RRC_INACTIVE, in which the UE is connected to the RAN, but is not actively utilizing resources. The RRC messages RRC Suspend and RRC Resume transition the UE from RRC_CONNECTED to and from RRC_INACTIVE states. NR RRC thus introduces RRC state transitions that do not exist in LTE; accordingly, the handling by UEs of some parameters, timers, and activities is not fully specified. Uncertainty over how various UEs may handle these parameters, timers, and activities could lead to UE behavior divergent from network expectations (or desires), requiring recovery signaling that would not be necessary if the UE behavior were explicitly specified.

In LTE, an RRC_CONNECTED UE enters RRC_IDLE by receiving an "RRCConnectionRelease" message from the network. That may contain a parameter called idleModeMobilityControlInfo. That field provides dedicated cell reselection priorities to be used for cell reselection, as specified in 3GPP TS <NUM> V14. The RRC Connection Release message is used to command the release of an RRC connection. The content of this message can be derived from 3GPP specification <NUM> as shown below:.

Signalling radio bearer: SRB1
RLC-SAP: AM
Logical channel: DCCH
Direction: E-UTRAN to UE
<IMG>.

In LTE, the UE behavior associated to these parameters is defined as follows in the RRC specifications 3GPP TS <NUM> V15. <NUM>, section <NUM>. <NUM> Reception of the RRCConnectionRelease by the UE:
The UE shall:
[.

The technical standard <NUM> further comprises in section <NUM>. <NUM> the behaviour of the UE on expiry of timer T320:
The UE shall:.

In LTE, these parameters only make sense when the UE enters RRC_IDLE, with or without a suspend indicator. And, from that state, the UE can only enter RRC_CONNECTED either by establishing or resuming an RRC connection. Hence, upon entering RRC_CONNECTED some actions are performed to discard or clean up these parameters and/or stop related timer(s), such as T320. That is shown in LTE standard TS <NUM> upon receiving the RRCConnectionSetup or RRCConnectionResume message.

It has been agreed in NR that the UE should possibly receive parameters in the RRCRelease and/or RRCSuspend message upon entering RRC_IDLE and/or RRC_INACTIVE. However, in addition to the procedures in LTE where an RRC_IDLE (with suspend indicator) can attempt to enter RRC_CONNECED by starting a resume procedure and possibly entering RRC_CONNECTED, additionally, the following aspects has been agreed for NR RRC which is different from LTE RRC.

<FIG> depicts signaling in NR RRC, in which the network may respond to a ResumeRequest from the UE with a Suspend message which immediately orders the UE back to RRC_INACTIVE state. Also, this message will be encrypted. In LTE it is not possible to send a suspend message (Release with suspend indication) directly to the UE trying to resume the connection.

<FIG> depicts signaling in NR RRC, in which the network may respond to a ResumeRequest from the UE with a Release message which immediately orders the UE to RRC_IDLE state. Also, this message will be encrypted. In LTE it is not possible to send a release message (Release) directly to the UE trying to resume the connection.

Due to the differences above the following issues occur with handling parameters possibly provided to a UE entering RRC_INACTIVE, e.g., T320 timer, and redirection information:
Since the UE may receive more messages in NR in response to the ResumeRequest (e.g. RRC Reject, RRC Release, RRC Suspend) it is not enough to just stop the timer when receiving the Resume or the Setup message as in LTE.

For the carrier redirection information, in the current state of the art and new NR procedures, it is unclear what would be the UE behavior. In the LTE specifications TS <NUM> the following is defined:
<IMG>.

The redirectedCarrierlnfo indicates a carrier frequency (downlink for FDD) and is used to redirect the UE to an E-UTRA or an inter-RAT carrier frequency, by means of the cell selection upon leaving RRC_CONNECTED as specified in 3GPP TS <NUM> V14.

If the UE has entered RRC_INACTIVE and has received a redirectedCarrierlnfo field, and, after trying to resume the connection it either receives an RRCSuspend or RRCRelease without a redirectedCarrierinfo field, then according to the existing need code, i.e., Need ON, as defined in 3GPP standards, it is not clear whether the UE shall use the previously provided value, which is still stored, or if that should be discarded.

For the idleModeMobilityControllnfo field, in the current state of the art and new NR procedures, if the UE enters RRC_INACTIVE and the Suspend message contains the idleModeMobilityControllnfo (or equivalent), the timer T320 may never stop if the UE tries to resume and is suspended or released in response (e.g., in the case of RAN-based Notification Area, or RNA, updates). Also, even if a new timer and parameters are provided in the Release or Suspend message, it remains ambiguous whether the UE shall use the new values or the old values, as these may still be stored at the UE when the UE tries to resume (in case T320 is still running).

When it comes to need codes, that field has a Need OP indication in the respective 3GPP standard, which means the following:.

<NPL>" discloses UE state machine and state transitions in NR and further discloses that a UE in INACTIVE, trying to resume an RRC connection, can receive MSG4 sent over SRB1 with at least integrity protection to move the UE back into INACTIVE (i.e. not rejected).

<NPL>" discloses a procedure to release a RRC connection. The UE shall, if the RRCConnectionRelease message includes the idleModeMobilityControlInfo, store the cell reselection priority information provided by the idleModeMobilityControlInfo. If not, the UE shall apply the cell reselection priority information broadcasted in the system information.

As it can be seen, there is nothing in LTE specified upon the reception of an RRCConnectionRelease message as that is not possible to occur when the UE is in RRC_IDLE.

The Background section of this document is provided to place embodiments of the present invention in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Approaches described in the Background section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. However, this invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

For simplicity and illustrative purposes, the present invention is described by referring mainly to an exemplary embodiment thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be readily apparent to one of ordinary skill in the art that the present invention may be practiced without limitation to these specific details. In this description, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention. At least some of the embodiments may be described herein as applicable in certain contexts and/or wireless network types for illustrative purposes, but the embodiments are similarly applicable in other contexts and/or wireless network types not explicitly described.

According to one or more embodiments described, a new mechanism is introduced for handling parameters received when the UE enters RRC_INACTIVE upon the UE trying to resume an RRC connection and, as a response, receives a Release or Suspend message.

In one embodiment a method comprises stopping the timer associated to the mobilityControllnfo (equivalent to T320), if running, and discarding the parameters with mobilityControllnfo upon:.

In another embodiment a method comprises discarding information received in a Release or Suspend message upon:.

In one embodiment, it comprises stopping the timer associated to the mobilityControllnfo (equivalent to T320), if running, and discarding the parameters with mobilityControllnfo upon:.

According to embodiments of the present invention, the exact UE actions are known by the network. Also, the network has the possibility to unambiguously configure the UE and obtain an expected behavior. In the particular case of the equivalent timer to T320, the UE stopping the timer avoids the UE to keep running the procedure associated to mobilityControllnfo even though the network does not want that behavior.

According to one embodiment, a method comprises:.

A used herein, idle/inactive mobility related parameters can be mobilityControllnfo (e.g. idleMobilityControllnfo), redirection carrier information, cell reselection offsets, cell quality derivation parameters, etc..

To exemplify the mechanism, described below is the usage in the case of the IdleMobilityControllnfo field provided in RRC Release or RRC suspend and controlled by a timer. The field redirectedCarrierOffsetDedicated is also included. The UE shall:.

Editor's Note: FFS Whether we will instead use RRCRelease (e.g. with suspend indicator). The UE shall:.

<FIG> depicts a method <NUM> of managing Radio Resource Control (RRC) states, performed by a wireless device operative in a wireless communication network, in accordance with particular embodiments. While in an RRC_INACTIVE state, and performing actions related to idle or inactive mobility, an RRC message is sent to the network requesting to enter an RRC_CONNECTED state (block <NUM>). An RRC message is received from the network directing the wireless device to enter an RRC_IDLE or remain in RRC_INACTIVE state (block <NUM>). In response to the received RRC message, one or more stored dedicated idle or inactive mobility related parameters are discarded (block <NUM>). Also, in response to the received RRC message, activities associated with the dedicated idle or inactive mobility related parameters are discontinued (block <NUM>).

<FIG> depicts a method <NUM> of managing a wireless device, performed by a base station operative in a wireless communication network implementing a Radio Resource Control (RRC) protocol, in accordance with other particular embodiments. An RRC message, requesting to enter an RRC_CONNECTED state, is received from a wireless device in RRC_IDLE or RRC_INACTIVE state (block <NUM>). In response to the request, an RRC message is sent to the wireless device directing the wireless device to enter an RRC_IDLE or remain in RRC_INACTIVE state (block <NUM>). The wireless device is managed assuming that, in response to the RRC message received by the wireless device, it discards one or more stored idle or inactive mobility related parameters (block <NUM>). The wireless device is further managed assuming that, in response to the RRC message received by the wireless device, it discontinues activities associated with the idle or inactive mobility related parameters (block <NUM>).

The apparatuses described herein may perform the methods <NUM>, <NUM> herein and any other processing by implementing any functional means, modules, units, or circuitry. In one embodiment, for example, the apparatuses comprise respective circuits or circuitry configured to perform the steps shown in the method figures. The circuits or circuitry in this regard may comprise circuits dedicated to performing certain functional processing and/or one or more microprocessors in conjunction with memory. For instance, the circuitry may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory may include program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein, in several embodiments. In embodiments that employ memory, the memory stores program code that, when executed by the one or more processors, carries out the techniques described herein.

<FIG> for example illustrates a wireless device <NUM> as implemented in accordance with one or more embodiments. A wireless device <NUM> is any type device capable of communicating with a network node and/or access point using radio signals. A wireless device <NUM> may therefore refer to a machine-to-machine (M2M) device, a machine-type communications (MTC) device, a Narrowband Internet of Things (NB loT) device, etc. The wireless device <NUM> may also be referred to as a User Equipment (UE), such as a cellular telephone or "smartphone," however, the term UE should be understood to encompass any wireless device <NUM>. A wireless device <NUM> may also be referred to as a radio device, a radio communication device, a wireless device, a wireless terminal, or simply a terminal - unless the context indicates otherwise, the use of any of these terms is intended to include device-to-device UEs or devices, machine-type devices, or devices capable of machine-to-machine communication, sensors equipped with a wireless device, wireless-enabled table computers, mobile terminals, smart phones, laptop-embedded equipped (LEE), laptop-mounted equipment (LME), USB dongles, wireless customer-premises equipment (CPE), etc. In the discussion herein, the terms machine-to-machine (M2M) device, machine-type communication (MTC) device, wireless sensor, and sensor may also be used. It should be understood that these devices, although referred to as UEs, but may be configured to transmit and/or receive data without direct human interaction.

In some embodiments, the wireless device <NUM> includes a user interface <NUM> (display, touchscreen, keyboard or keypad, microphone, speaker, and the like); in other embodiments, such as in many M2M, MTC, or NB loT scenarios, the wireless device <NUM> may include only a minimal, or no, user interface <NUM> (as indicated by the dashed lines of block <NUM> in <FIG>). The wireless device <NUM> also includes processing circuitry <NUM>; memory <NUM>; and communication circuitry <NUM> connected to one or more antennas <NUM>, to effect wireless communication across an air interface to one or more radio network nodes, such as a base station, and/or access points. As indicated by the dashed lines, the antenna(s) <NUM> may protrude externally from the wireless device <NUM>, or the antenna(s) <NUM> may be internal. In some embodiments, a wireless device <NUM> may include a sophisticated user interface <NUM>, and may additionally include features such as a camera, accelerometer, satellite navigation signal receiver circuitry, vibrating motor, and the like (not depicted in <FIG>).

According to embodiments of the present invention, the memory <NUM> is operative to store, and the processing circuitry <NUM> operative to execute, software which when executed is operative to cause the wireless device <NUM> to managing Radio Resource Control (RRC) states. In particular, the software, when executed on the processing circuitry <NUM>, is operative to perform the method <NUM> described and claimed herein. The processing circuitry <NUM> in this regard may implement certain functional means, units, or modules.

<FIG> illustrates a schematic block diagram of a wireless device <NUM> in a wireless network according to still other embodiments. As shown, the wireless device <NUM> implements various functional means, units, or modules, e.g., via the processing circuitry <NUM> in <FIG> and/or via software code. These functional means, units, or modules, e.g., for implementing the method(s) herein, include for instance: an RRC message sending unit <NUM>, an RRC message receiving unit <NUM>, an IDLE/INACTIVE mobility parameter discarding unit <NUM>, and an IDLE/INACTIVE mobility activity discontinuing unit <NUM>.

The RRC message sending unit <NUM> is configured to, while in an RRC_INACTIVE state, and performing actions related to idle or inactive mobility, send an RRC message to the network requesting to enter an RRC_CONNECTED state. The RRC message receiving unit <NUM> is configured to receive an RRC message from the network directing the wireless device to enter an RRC_IDLE or remain in RRC_INACTIVE state. The IDLE/INACTIVE mobility parameter discarding unit <NUM> is configured to, in response to the received RRC message, discard one or more stored dedicated idle or inactive mobility related parameters. The IDLE/INACTIVE mobility activity discontinuing unit <NUM> is configured to, in response to the received RRC message, discontinue activities associated with the dedicated idle or inactive mobility related parameters.

<FIG> depicts a base station <NUM> operative in a wireless communication network. The base station <NUM> includes processing circuitry <NUM>; memory <NUM>; and communication circuitry <NUM> connected to one or more antennas <NUM>, to effect wireless communication across an air interface to one or more wireless devices <NUM>. As indicated by the broken connection to the antenna(s) <NUM>, the antenna(s) <NUM> may be physically located separately from the base station <NUM>, such as mounted on a tower, building, or the like. Although the memory <NUM> is depicted as being internal to the processing circuitry <NUM>, those of skill in the art understand that the memory <NUM> may also be external. Those of skill in the art additionally understand that virtualization techniques allow some functions nominally executed by the processing circuitry <NUM> to actually be executed by other hardware, perhaps remotely located (e.g., in the so-called "cloud"). The base station <NUM> is known in LTE as a eNodeB or eNB, and in New Radio (NR) as gNB. In general, in other wireless communication networks, the base station <NUM> may be known as a Radio Base Station, Base Transceiver Station, Access Point, or the like.

According to one embodiment of the present invention, the processing circuitry <NUM> is operative to cause the base station <NUM> to manage a wireless device <NUM> in a wireless communication network implementing a Radio Resource Control (RRC) protocol. In particular, the processing circuitry <NUM> is operative to perform the method <NUM> described and claimed herein. The processing circuitry <NUM> in this regard may implement certain functional means, units, or modules.

<FIG> illustrates a schematic block diagram of a base station <NUM> in a wireless network according to still other embodiments. As shown, the base station <NUM> implements various functional means, units, or modules, e.g., via the processing circuitry <NUM> in <FIG> and/or via software code. These functional means, units, or modules, e.g., for implementing the method <NUM> herein, include for instance: an RRC message receiving unit <NUM>, an RRC message sending unit <NUM>, and a wireless device management unit <NUM>.

The RRC message receiving unit <NUM> is configured to receive from a wireless device in RRC_IDLE or RRC_INACTIVE state, an RRC message requesting to enter an RRC_CONNECTED state. The RRC message sending unit <NUM> is configured to, in response to the request, send an RRC message to the wireless device directing the wireless device to enter an RRC_IDLE or remain in RRC_INACTIVE state. The wireless device management unit <NUM> is configured to manage the wireless device assuming that, in response to the RRC message received by the wireless device, it discards one or more stored idle or inactive mobility related parameters, and further to manage the wireless device assuming that, in response to the RRC message received by the wireless device, it discontinues activities associated with the idle or inactive mobility related parameters.

A computer program comprises instructions which, when executed on at least one processor of an apparatus, cause the apparatus to carry out any of the respective processing described above. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above.

The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are.

Other objectives, features and advantages of the enclosed embodiments will be apparent from the description.

Claim 1:
A method (<NUM>) of managing Radio Resource Control, RRC, states, performed by a wireless device (<NUM>) operative in a <NUM> wireless communication network, the method (<NUM>) is characterized by:
while in an RRC_INACTIVE state, and performing activities associated with dedicated cell reselection priority information, sending (<NUM>) an RRC message to the network requesting to enter an RRC_CONNECTED state;
receiving (<NUM>), in response to the RRC message requesting to enter an RRC_CONNECTED state, an RRCRelease message from the network directing the wireless device (<NUM>) to enter an RRC_IDLE state or to remain in RRC_INACTIVE state; and
in response to the received RRCRelease message and if the received RRCRelease message does not include dedicated cell reselection priority information,
if dedicated cell reselection priority information is stored,
discarding (<NUM>) the stored dedicated cell reselection priority information, discontinuing (<NUM>) the activities associated with the dedicated cell reselection priority information and
applying cell reselection priority information received in broadcasted system information;
wherein performing activities associated with dedicated cell reselection priority information comprises performing cell reselection according to dedicated priorities while a validity timer of the cell reselection priority parameter is running.