WUS FOR PAGING FOR RRC INACTIVE STATES

In accordance with an example embodiment of the present invention, a method comprising determining, by a user equipment in a radio resource control inactive state, whether information has been received from a wireless network, wherein the information is configured to cause the user equipment to access the network; and triggering, by the user equipment and in response to receiving the information, an access to the wireless network, is disclosed.

TECHNICAL FIELD

This invention relates generally to wireless networks and, more specifically, relates to wake-up signals (WUSs) intended to wake up user equipment from an inactive state.

BACKGROUND

The third generation partnership project (3GPP) is defining a physical downlink control channel (PDCCH)-based power saving signal/channel to instruct a user equipment (UE) to wake up at the next discontinuous reception (DRX) On-Duration for radio resource control

(RRC) Connected UEs. Recently RANI (RAN working group1is responsible for the development of specifications dealing with evolved universal terrestrial radio access, and beyond) denoted such signal as “DCI with CRC scrambled by PS-RNTI”, where DCI is downlink control channel, CRC is cyclic redundancy check, PS stands for power saving, and RNTI is radio network temporary identifier. For simplicity, this is denoted herein as WUS (Wake Up Signaling), as this signaling is indeed used to indicate to the UE to initiate PDCCH monitoring (that is, wake up) for scheduled data at the coming On-Duration. Specifically, the network configures WUS occasions for the UE in dedicated RRC signaling, e.g., with an RRCReconfiguration message.

If a UE does not receive the WUS during the network-defined WUS occasion(s), the UE will assume there is no data and can skip monitoring the PDCCH during the next DRX On-Duration, thus saving power when no data is present. To minimize false alarms (leading to waking up a UE unnecessarily), the WUS signal is targeted to a UE specific identifier, the PS-RNTI. It is noted that the WUS design is still under discussion in the work item on UE power saving in new radio (NR) (see RP-191607, CATT, CAICT, “New WID: UE Power Saving in NR”, 3GPP TSG RAN Meetings #84, Newport Beach, USA, 3-6 Jun. 2019) in conjunction with DRX.

SUMMARY

In accordance with some embodiments, a method may include determining, by a user equipment in a radio resource control inactive state, whether information has been received from a wireless network, wherein the information is configured to cause the user equipment to access the network. The method may further include triggering, by the user equipment and in response to receiving the information, an access to the wireless network.

In accordance with some embodiments, a method may include sending, by network node and toward a user equipment in a radio resource control inactive state, information that is configured to cause the user equipment to access the network. The method may further include receiving, by the network node and in response to sending the information, an access from the user equipment to the wireless network.

In accordance with some embodiments, an apparatus may include means for performing a process according to any of the methods.

In accordance with some embodiments, a non-transitory computer readable medium may include program instructions stored thereon for performing the method according to any of the methods.

In accordance with some embodiments, an apparatus may include at least one processor; and at least one memory comprising computer program code, the at least one memory and the computer program code are configured, with the at least one processor to cause the apparatus at least to performing a process according to any of the methods.

DETAILED DESCRIPTION OF THE DRAWINGS

Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the examples.

Abbreviations that may be found in the specification and/or the drawing figures are defined below, at the end of this Detailed Description section.

The exemplary embodiments herein describe techniques for WUS for paging for RRC INACTIVE states. Additional description of these techniques is presented after a system into which the exemplary embodiments may be used is described.

Turning toFIG.1, this figure shows a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced. A user equipment (UE)110, two radio access network (RAN) nodes170and170-1, and network element(s)190are illustrated. InFIG.1, a user equipment (UE)110is in wireless communication with a wireless network100.

A UE is a wireless, typically mobile device that can access a wireless network. The UE110includes one or more processors120, one or more memories125, and one or more transceivers130interconnected through one or more buses127. Each of the one or more transceivers130includes a receiver, Rx,132and a transmitter, Tx,133. The one or more buses127may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers130are connected to one or more antennas128. The one or more memories125include computer program code123. The UE110includes a control module140, comprising one of or both parts140-1and/or140-2, which may be implemented in a number of ways. The control module140may be implemented in hardware as control module140-1, such as being implemented as part of the one or more processors120. The control module140-1may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module140may be implemented as control module140-2, which is implemented as computer program code123and is executed by the one or more processors120. For instance, the one or more memories125and the computer program code123may be configured to, with the one or more processors120, cause the user equipment110to perform one or more of the operations as described herein. The UE110communicates with RAN node170via a wireless link111.

The RAN nodes170and170-1are base stations that provide access by wireless devices such as the UE110to the wireless network100. Both nodes, as described in more detail below, may be gNBs and therefore may be referred to as such below. The RAN node170may be an anchor gNB and the RAN node170-1may be a target gNB. The RAN node170is considered to be representative of the RAN node170-1, and therefore the internal circuitry of the RAN node170is only described below.

The RAN node170may be, for instance, a base station for 5G, also called New Radio (NR). In 5G, the RAN node170may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (e.g., the network element(s)190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU)196and distributed unit(s) (DUs) (gNB-DUs), of which DU195is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected with the gNB-DU. The F1 interface is illustrated as reference198, although reference198also illustrates a link between remote elements of the RAN node170and centralized elements of the RAN node170, such as between the gNB-CU196and the gNB-DU195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface198connected with the gNB-CU. Note that the DU195is considered to include the transceiver160, e.g., as part of an RU, but some examples of this may have the transceiver160as part of a separate RU, e.g., under control of and connected to the DU195. The RAN node170may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station.

The RAN node170includes one or more processors152, one or more memories155, one or more network interfaces (N/W I/F(s))161, and one or more transceivers160interconnected through one or more buses157. Each of the one or more transceivers160includes a receiver, Rx,162and a transmitter, Tx,163. The one or more transceivers160are connected to one or more antennas158. The one or more memories155include computer program code153. The CU196may include the processor(s)152, memories155, and network interfaces161. Note that the DU195may also contain its own memory/memories and processor(s), and/or other hardware, but these are not shown.

The RAN node170includes a control module150, comprising one of or both parts150-1and/or150-2, which may be implemented in a number of ways. The control module150may be implemented in hardware as control module150-1, such as being implemented as part of the one or more processors152. The control module150-1may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module150may be implemented as control module150-2, which is implemented as computer program code153and is executed by the one or more processors152. For instance, the one or more memories155and the computer program code153are configured to, with the one or more processors152, cause the RAN node170to perform one or more of the operations as described herein. Note that the functionality of the control module150may be distributed, such as being distributed between the DU195and the CU196, or be implemented solely in the DU195.

The one or more network interfaces161communicate over a network such as via the links176and131. Two or more RAN nodes170communicate using, e.g., link176. The link176may be wired or wireless or both and may implement, e.g., an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

The one or more buses157may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers160may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU)195for gNB implementation for 5G, with the other elements of the RAN node170possibly being physically in a different location from the RRH/DU, and the one or more buses157could be implemented in part as, e.g., fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node170to the RRH/DU195. Reference198also indicates those suitable network link(s).

It is noted that description herein indicates that “cells” perform functions, but it should be clear that the base station that forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For instance, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station's coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

The wireless network100may include a network element or elements190that may include core network functionality, and which provides connectivity via a link or links181with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(s)) and/or user plane functions (UPF(s)) and/or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality. These are merely exemplary functions that may be supported by the network element(s)190, and note that both 5G and LTE functions might be supported. The RAN node170is coupled via a link131to a network element190. The link131may be implemented as, e.g., an NG interface for 5G, or an S1 interface for LTE, or other suitable interface for other standards. The network element190includes one or more processors175, one or more memories171, and one or more network interfaces (N/W I/F(s))180, interconnected through one or more buses185. The one or more memories171include computer program code173. The one or more memories171and the computer program code173are configured to, with the one or more processors175, cause the network element190to perform one or more operations.

In general, the various embodiments of the user equipment110can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, vehicles with a modem device for wireless V2X (vehicle-to-everything) communication, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances (including Internet of Things, IoT, devices) permitting wireless Internet access and possibly browsing, IoT devices with sensors and/or actuators for automation applications with wireless communication tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

Having thus introduced one suitable but non-limiting technical context for the practice of the exemplary embodiments of this invention, the exemplary embodiments will now be described with greater specificity.

As further introduction, the RRC Inactive state is a new independent RRC state that was introduced in 3GPP NR Rel-15, complementing the existing states, RRC_CONNECTED and RRC_IDLE, with the goal of lean signaling and energy-efficient support of NR services (see 3GPP TSs 38.300/38.304/38.331). The NR RRC state machine comprising the three states is illustrated inFIG.2. The RRC state machine200in 5G NR is illustrated in this figure. Note that the states may be shown in all capital letters, as in the figure (e.g., “RRC_CONNECTED”). The states are the same, however, if capital letters are not used. That is, “RRC_CONNECTED” is the same as RRC Connected or RRC connected. A UE110is either in the RRC_CONNECTED state210or in the RRC_INACTIVE state220when an RRC connection has been established. This is illustrated by reference240, which states the connection management state is CM-CONNECTED. If this is not the case, i.e., no RRC connection is established, the UE is in RRC_IDLE state230. This is illustrated by reference250, which states that the connection management state is CM-IDLE.FIG.2also lists the following actions: data transfer actions260; actions270, which include RRC state transition timer expires or data inactivity; and actions280, which are overload/“failure” cases.

As indicated inFIG.2, the following transitions can be made: from the RRC_CONNECTED state210to the RRC_INACTIVE state220via a suspend action270-1or a reject action280-1; from the RRC_INACTIVE state220to the RRC_CONNECTED state210via the resume action260-1; from the RRC_INACTIVE state220to the RRC_IDLE state230via the release state280-2(where the Release is marked with an asterisk, *, which is explained using reference290); from the RRC_CONNECTED state210to the RRC_IDLE state230via the release action270-2or the reject action280-3; and from the RRC_IDLE state230to the RRC_CONNECTED state210via the establishment action260-2. Reference290indicates the following: (*) Besides failure cases, the transition RRC_INACTIVE to (→) IDLE is network initiated, and the UE has to move to CONNECTED first. Note that while the term “state” is used herein, the term “mode” is also commonly used for these, so that, e.g., the RRC Connected state is the same as the RRC Connected mode.

Although the design of the RRC state machine200was conceived particularly for mMTC/MIoT services [see 3GPP TR 22.824, such as 3GPP TR 22.824 V16.0.0 (2018-09)], it could be beneficial to efficiently deliver small and infrequent traffic of eMBB and URLLC services as well. The RRC_INACTIVE state220enables quickly resuming the RRC connection and starting the transmission of small or sporadic data with a much lower initial access delay and associated signaling overhead as compared to the RRC_IDLE state230(by allowing a faster transition to the RRC_CONNECTED state having about 10 ms CP delay).

This is achieved mainly thanks to reduced control signaling required for requesting and obtaining the resume of a suspended RRC connection, which results in UE power saving. At the same time, a UE in the RRC_INACTIVE state220is able to achieve similar power savings as in the RRC_IDLE state230, benefiting from, e.g., a much larger period between PDCCH monitoring (e.g., paging) and relaxed measurements (e.g., for cell (re)-selection) compared to the RRC_CONNECTED state. In other words, PDCCH monitoring is less frequent. Furthermore, compared to keeping the UE in the RRC_CONNECTED state210, the new state minimizes mobility signaling both to RAN (e.g., RRC measurement reporting, HO messages) and to the core network (e.g., to/from the AMF) since the UE is still in a CM-CONNECTED state. A UE in the RRC_INACTIVE state210can move within an area configured by the RAN node170without any notification (i.e., RAN Notification Area (RNA)) and by using a unique identifier, which is the Inactive-RNTI (I-RNTI). More description of RNA can be found from, e.g., 3GPP TS 38.300 (see, e.g., 3GPP TS 38.300 V15.8.0 (2019-12)), clause 9.2.2, “Mobility in RRC_INACTIVE”. This RNA can cover a single or multiple cell(s) and shall be contained within the CN registration area. A RAN-based Notification Area Update (RNAU) procedure is run by the UE periodically and when the UE re-selects to a cell that does not belong to the configured RNA.

As indicated above, to minimize false alarms (leading to waking up a UE unnecessarily), the WUS signal is targeted to a UE specific identifier, the PS-RNTI. WUS in NR is applicable only to UEs in the RRC Connected state210. The basic WUS applied to RRC Inactive state220, referred herein as “regular WUS”, i.e., a WUS that triggers a UE in RRC Inactive state220to perform PDCCH monitoring for paging, has been briefly discussed in 3GPP, but not agreed upon. Besides that, the topic has not been considered so far. Therefore, potential UE power saving benefits of WUS cannot be currently exploited by RRC Inactive UEs.

Decoding of a regular paging message requires the PDSCH decoding operations, which are more complex compared to decoding of a WUS. Also, regular paging with Paging-RNTI (P-RNTI) wakes up multiple UEs, although the paging may not address all the UEs that received the paging indication. On the other hand, “regular WUS” for the RRC Inactive state220would require beam sweeping on all the beams. Furthermore, consecutive paging messages would require beam sweeping or some other beam tracking operations, which all together would cause significant overhead, and therefore these may not be desired.

According to the design being defined as per the Rel-16 UE Power saving in NR WID, the WUS is applicable only to UEs in the RRC Connected state210. WUS for paging in IDLE/INACTIVE states in NR was discussed in the Rel-16 UE power saving study item but was soon down-prioritized (see 3GPP TR 38.840) because it was assumed to cause network overhead due to beam sweeping. That is, the WUS transmission on every beam would be necessary when sending WUS to IDLE/INACTIVE state UEs because the network does not perform beam tracking for IDLE/INACTIVE state UEs, thus is unaware of the strongest/best beam.

WUS for paging is defined for NB-IoT. Concerning this, what follows is a short description. NB-IoT UEs, BL UEs or UEs in enhanced coverage can use WUS, when configured in the cell, to reduce the power consumption related to paging monitoring. When WUS is used in idle mode, the following are applicable:1) The WUS is used to indicate that the UE shall monitor MPDCCH or NPDCCH to receive paging in that cell;2) For a UE not configured with extended DRX, the WUS is associated to one paging occasion (N=1);3) For a UE configured with extended DRX, the WUS can be associated to one or multiple paging occasion(s) (N1) in a PTW;4) If UE detects the WUS, the UE shall monitor the following N paging occasions unless the UE has received a paging message;5) The paging operation in the MME is not aware of the use of the WUS in the eNB.

Thus, if WUS is detected, the UE shall monitor paging.

The exemplary embodiments herein address some or all of these issues and relate to extensions of WUS to the RRC Inactive state220and also relate at least to Rel-17 WID follow-up on the UE power saving in NR, whose scope will likely include power saving enhancements for the RRC Inactive state220. An overview is presented first, and then additional details are presented.

As an exemplary overview, an exemplary notion is introduced that WUS triggers a connection resume for RRC Inactive UEs. In an exemplary embodiment, upon receiving a UE-specific WUS indication, the UE in an RRC Inactive state220triggers the resume procedure (rather than triggering PDCCH monitoring for paging during the subsequent paging cycle), and thereby a WUS indication in RRC Inactive can replace completely a paging message. This approach is denoted as “Paging with WUS” and the required signal as “WUS for paging”. Note that during the standardization process, the information waking up the UE and triggering the UE to start an on-duration timer was called a wake-up signal. In a later phase, a terminology change was agreed upon, and this is now information is currently referred to as DCP (which currently refers to DCI with CRC scrambled by PS-RNTI). The WUS used herein, e.g., for paging purposes, also covers the DCP terminology.

In additional exemplary embodiments, the “WUS for paging” signal is used only in the presence of user plane (UP) data to be transmitted in the downlink. Instead “regular WUS”, i.e., WUS that triggers PDCCH monitoring for paging, can be used in the presence of non-user plane data (control plane, CP), such as System Information (SI) update, ETWS, and the like, because in these latter cases the paging message itself contains necessary information and cannot be skipped. “WUS for paging” can coexist with “regular WUS”. The UE can distinguish between the two signals (“WUS for paging” versus “regular WUS”), e.g., by using different UE IDs or by allocating (by the network) different WUS occasions for the two purposes. In the former, the UE in RRC Inactive will monitor WUS targeted to both IDs (i.e. monitoring whether the WUS DCI is scrambled with the UE ID configured either for UP data or CP data). In one example, the network can configure dedicated PS-RNTI identifiers for the UP and non-UP purposes to the UE in the RRC Connected state210, prior to move to the RRC Inactive state220. In another example, the PS-RNTI can be set equal to the I-RNTI.

The following are additional embodiments and aspects. These are merely exemplary, and they may be combined or alternative. In one embodiment, UE-specific WUS resources are configured for the UE in dedicated signaling, e.g., using an RRC Release message. In one aspect, UE specific WUS resources are monitored by the UE in the RRC_INACTIVE state220. In another possible aspect, the WUS triggers an RRC Resume procedure. In a further aspect, a WUS triggers (from the RRC Idle state230) an RRC Setup Request procedure (e.g., as the establishment action260-2inFIG.2). In an additional aspect, a WUS triggers a random access procedure, which may be performed in both the Resume and Setup request cases. In another further possible aspect, a WUS triggers system information acquisition. In an additional exemplary aspect, certain WUS occasions are configured for triggering an RRC Resume procedure. In an additional possible aspect, certain WUS occasions are configured for triggering system information acquisition. In yet another possible aspect, a UE110in the INACTIVE state220monitors WUS occasions and is allowed to skip paging monitoring.

Now that an exemplary overview has been provided, additional details are provided. The signaling flow chart and UE-side flow chart illustrating embodiments of this invention are shown inFIGS.3and4, respectively.FIG.3is a signaling diagram illustrating an exemplary embodiment for WUS for Paging for RRC Inactive States.FIG.4is a logic flow diagram performed by a UE for WUS for paging for RRC Inactive states. ForFIGS.3and4and any operations performed by the UE110, these are assumed to be performed under control of the control module140, and for any operations performed by a RAN node170,170-1, these are assumed to be performed under control of the corresponding control module150.

Turning toFIG.3, this figure illustrates signaling between the UE110, the RAN node170, as an anchor gNB in this example, and RAN node170-1, as a target gNB in this example. The UE context is stored in the anchor gNB. A target gNB is the gNB where the UE performs the RRC Resume procedure, and there can be many target gNBs. Note that the anchor gNB may itself be a target gNB under this definition. The target gNB170-1is within the RNA, and there could be one to multiple ones of these in the RNA. InFIG.3, there is an optional set of target gNBs to target gNB170-N. The gNB terms will be used for the examples ofFIGS.3and4, although as indicated above, a RAN node may take multiple different forms. The signaling310between the UE110and the anchor gNB170indicates the UE110is in an RRC Inactive state220with stored UE AS Inactive state context, including (incl.) Resume ID (I-RNTI) and (&) WUS configuration(s) including one or more PS-RNTI(s). Block320illustrates that the UE110is in the RRC_INACTIVE state220of the CM-Connected states240.

In block330, the anchor gNB170receives (as a first step) a RAN paging trigger, e.g., comprising downlink (DL) user plane (UP) data, and in signaling340(a second step) sends RAN paging to the target gNB170-1. The signaling in reference350, a third step, indicates a “WUS for paging” signaling is performed with a UE-specific WUS identifier, which is equal (=) to a first PS-RNTI. The signaling for reference350is between the UE110and either the anchor gNB170(as a target node) and one of the one or more target gNBs170-1through170-N. That is, only the target gNB can physically signal with UE via a radio interface (and the anchor gNB is a possible target gNB).

In block360, a fourth step, the UE receives the “WUS for paging” signaling and triggers a RRC Connection resume260-1(seeFIG.2). The signaling in reference370, a fifth step, indicates the UE110sends a paging response (e.g., via a random access procedure) using I-RNTI.

Referring toFIG.4, this figure is a logic flow diagram performed by a UE for WUS for Paging for RRC Inactive States. This figure also illustrates the operation of an exemplary method or methods, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.

In block410, the UE is in the RRC Inactive state220, with stored UE AS Inactive context, a Resume ID (e.g., I-RNTI), and (&) WUS configuration(s) including (incl.) one or more PS-RNTI(s) for UP/CP data. In block420, the UE110determines whether the WUS was received. If not (block420=No), the flow proceeds to block410. If the WUS was received (block420=Yes), the flow proceeds to block430.

In block430, the UE110determines whether the WUS ID is equal (=) to the ID for UP data, which was previously stored in block410. If so (block430=ID for UP data), in block450, the UE110triggers a connection resume procedure (see260-1inFIG.2), and sends a paging response, e.g., initiating a random access procedure. The term “triggering” is a term of art and is meant to mean that an RRC connection resume procedure is actually performed. The triggering at least sets off the actions that cause the RRC connection resume procedure to be performed. In block470, if a connection is resumed (e.g., as a result of the random access procedure and via an RRC connection being established), the UE110receives DL data from the network.

Although inFIG.3, the connection resume procedure was the RRC Connection resume procedure, other procedures may be used as illustrated in block455. This block illustrates the connection resume procedure may be any of the following: 1) RRC connection resume; 2) RRC setup request; or 3) System information acquisition. One possibility for the RRC connection resume and RRC setup request is via a RACH (random access channel) procedure, as illustrated by block477.

While implementing a RACH procedure is one possibility, other options are possible. For instance, upon receiving the information in blocks420and430, the UE might access the network without performing a RACH procedure, e.g., in case time-alignment is valid. Also, the UE might be pre-configured (e.g., by the gNB170) with downlink persistent radio resources (e.g., in the form of semi-persistent scheduling, SPS, resources) that the UE is configured to access upon receiving the information in blocks420and430, such as small data reception in an RRC Inactive state over SPS resources triggered by a WUS indication (with or without prior random access).

Additionally, for the RRC setup request, this is from the RRC Idle state230(with reference also toFIG.2) and is one example of an establishment action260-2. As block479illustrates, the triggering that occurs in block450can trigger a state transition from the INACTIVE state220to the IDLE state230followed by an access attempt (e.g., of the RRC setup request as establishment action260-2).

If the WUS ID is not equal to the ID for UP data (block430=ID for CP data), in block440, the UE monitors PDCCH for paging. In block460, if paging decoding succeeds, the UE110receives paging on the PDCCH and also control data in the paging.

In the example of420and the description above, it has been assumed that the WUS is a defined WUS. As indicated by block415, this is only one option, however, and this information can be, e.g., information such as DCI, DCI including a wake-up indication, a certain DCI format, a wake-up indication, a defined wake-up signal, DCP (which currently refers to DCI with CRC scrambled by PS-RNTI), and/or physical layer signaling.

In additional embodiments, the anchor gNB170provides to the target cells (e.g., in the target gNBs170-1), during Xn-based RAN paging within the RNA, the PS-RNTI(s) assigned to an RRC Inactive UE as well as the associated WUS configuration (e.g., WUS occasions, preceding time of the WUS window as compared to a paging cycle).

In further embodiments, the PS-RNTI(s) are discarded by the UE110upon moving to the RRC Connected state210, and instead are retained by the UE when the resume triggered by the “WUS for paging” does not lead to an RRC state change, i.e. the UE is moved back to the RRC Inactive state220after the DL data transfer that triggered the paging. The same applies to cases where upon resuming for small data transmission (SDT) in the uplink, the UE110is moved back to the RRC Inactive state200after the UL data transfer. In other words, the UE keeps the PS-RNTI(s) if the UE preformed an SDT.

Relating to error scenarios, where the network has lost the UE when the UE was in an INACTIVE state (i.e., the UE has moved autonomously from the RRC Inactive state220to the RRC Idle state230, e.g., due to out-of-coverage situations), the UE would not monitor for “WUS for paging” any longer and would instead be paged with the Core Network (CN)/idle mode identifier, i.e. NG-5G-S-TMSI (a Temporary Mobile Subscriber Identity). Until the network detects that the UE moved to the RRC Idle state230(e.g., based on missing a periodic RNA update), the use of WUS for paging targeted to Inactive mode related IDs might be missed by the UE and lead to a paging failure similarly as if—in conventional techniques—the network would have sent a paging message addressed to the I-RNTI.

Technical effects and advantages include the following. Paging with WUS is more efficient than regular paging both for the UE and network accounting both UE power saving and network efficiency, for at least the following reasons.

For the UE, paging with WUS requires less UE power consumption compared to decoding regular paging because this type of paging avoids starting the PDSCH decoding operations associated to the regular paging unnecessarily (these should be started in case of regular paging during the PDCCH decoding in case the decoding indicates the presence of a paging message). Also, depending on the network configuration of WUS, the WUS window (during which WUS occasions are placed that are to be monitored by the UE) may be more power friendly (e.g., the WUS window is expected to be shorter and less inter-spaced than the paging occasions to monitor, and possibly with fewer decoding attempts than in regular PDCCH monitoring). Additionally, regular paging with Paging-RNTI (P-RNTI) may result in waking up multiple UEs, so this paging may cause unnecessary power consumption for other UEs too.

For the network, the WUS-specific DCI format defined by 3GPP (i.e., DCI-3_0) will likely have a smaller payload than paging DCI, so PDCCH capacity/coverage can be improved compared to regular paging. Also, although the WUS for paging has to be transmitted on every beam of the paging cell(s), the network can still save paging transmissions on every beam, which would be required too.

(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.”

This definition of circuitry applies to all uses of this term in this application, including in any examples. 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 example 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.

Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., inFIG.1. A computer-readable medium may comprise a computer-readable storage medium (e.g., memories125,155,171or other device) that may be any media or means that can contain, store, and/or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals.

Although various aspects are set out above, other aspects comprise other combinations of features from the described embodiments, and not solely the combinations described above.

The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:3GPP third generation partnership project5G fifth generation5GC 5G core networkAMF access and mobility management functionAS access stratumBL bandwidth limitedBWP bandwidth partCN core networkCP control planeCRC cyclic redundancy checkCSI channel-state informationCU central unitDCI downlink control informationDCP DCI with CRC scrambled by PS-RNTIDRX discontinuous receptionDU distributed uniteMBB enhanced mobile broadbandeNB (or eNodeB) evolved Node B (e.g., an LTE base station)EN-DC E-UTRA-NR dual connectivityen-gNB or En-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as secondary node in EN-DCETWS earthquake & tsunami warning systemE-UTRA evolved universal terrestrial radio access, i.e., the LTE radio access technologygNB (or gNodeB) base station for 5G/NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GCHO handoverID identificationI/F interfaceIRNTI or I-RNTI inactive-RNTILTE long term evolutionMAC medium access controlMIoT massive Internet of thingsMME mobility management entitymMTC massive machine type communicationsMPDCCH MTC physical downlink channelMTC machine type communicationsNB-IoT narrowband Internet of thingsng or NG next generationng-eNB or NG-eNB next generation eNBNG-5G-S-TMSI 5G S-temporary mobile subscriber identityNR new radioN/W or NW networkPCell primary cellPDCCH physical downlink control channelPDCP packet data convergence protocolPDSCH physical downlink shared channelPHY physical layerPS-RNTI power saving-RNTIPTW paging time windowPUCCH physical uplink control channelPUSCH physical uplink shared channelRAN radio access networkRel releaseRLC radio link controlRNA RAN notification areaRNAU RAN notification area updateRNTI radio network temporary identifierRRC radio resource controlRRH remote radio headRRM Radio resource managementRU radio unitRx receiverSDAP service data adaptation protocolSDT small data transmissionSGW serving gatewaySI system informationSIB system information blockSMF session management functionSpCell special cellTS technical specificationTx transmitterUE user equipment (e.g., a wireless, typically mobile device)UP user planeUPF user plane functionURLLC ultra reliable low latency communicationsWID work item descriptionWUS wake-up signaling