WO2018206821A1

WO2018206821A1 - Timer-controlled idle mode and non-pageable mode

Info

Publication number: WO2018206821A1
Application number: PCT/EP2018/062419
Authority: WO
Inventors: Anders Berggren; Svante ALNÅS
Original assignee: Sony Mobile Communications Inc.; Sony Mobile Communications Ab
Priority date: 2017-05-12
Filing date: 2018-05-14
Publication date: 2018-11-15

Abstract

A method includes: releasing a data connection between a communication device and a network; and in response to said releasing of the data connection: starting a timer and operating the communication device in a first mode, the communication device being pageable by the network in the first mode; and in response to expiry of the timer: operating the communication device in a second mode, the communication device not being pageable by the network in the second mode.

Description

Timer-controlled idle mode and non-pageable mode

TECHNICAL FIELD Various examples of the invention generally relate to operating a communication device in a mode in which the communication device is not pageable by the network. Various examples of the invention specifically relate to operating the communication device in the non-pageable mode in response to expiry of a timer.

BACKGROUND

With the ongoing proliferation of wireless communication, the reduction of power consumption of communication devices (sometimes also referred to as user equipment, UE) is gaining importance. They are techniques known to operate UEs in power-save modes. One example of a power-save mode is the so-called Mobile Initiated Connection Only (MICO) mode. See Third Generation Partnership Project (3GPP) Technical Specification (TS) 23.501 , version 0.3.1 , section 5.4.1 .3. The UE is able to request during registration/re-registration the MICO mode and the network may accept or reject operation of the UE in MICO mode. If the UE is operated in MICO mode, the receiver of the UE is persistently transitioned into a sleep state, sometimes also referred to as inactive state. Hence, operation of the UE in MICO mode includes the network not paging the UE. Operation of the UE in MICO mode further includes the UE not listening for paging signals. Consequently, when being operated in MICO mode, it is the UE which initiates communication on the wireless link between the network and the UE. Only in response to such initiation of the communication by the UE, downlink (DL) data may be transmitted from the network to the UE, if required.

Hence, there are certain scenarios conceivable where operation of the UE in MICO mode can result in certain drawbacks. For example, if uplink (UL) data is transmitted by the UE via a base station (BS) to a packet data network (PDN), and the response from the packet data network is delayed while the UE being operated in MICO mode, i.e. if the UE is transferred to MICO mode, before any late response from some application server outside the network has been received by the network. SUMMARY Therefore, a need exists for advanced techniques of operating a UE in a mode in which it is not pageable by the network. In particular, a need exists for such techniques which mitigate or overcome at least some of the above-identified drawbacks.

A method comprises releasing a data connection between a communication device and a network. The method further comprises in response to said releasing of the data connection: starting a timer and operating the communication device in a first mode, the communication device being pageable by the network in the first mode. The method further comprises in response to expiry of the timer: operating the communication device in a second mode, the communication device not being pageable by the network in the second mode.

A computer program product comprises program code executable by at least one processor. Executing the program code causes the at least one processor to perform a method. The method comprises releasing a data connection between a communication device and a network. The method further comprises in response to said releasing of the data connection: starting a timer and operating the communication device in a first mode, the communication device being pageable by the network in the first mode. The method further comprises in response to expiry of the timer: operating the communication device in a second mode, the communication device not being pageable by the network in the second mode.

A computer program comprises program code executable by at least one processor. Executing the program code causes the at least one processor to perform a method. The method comprises releasing a data connection between a communication device and a network. The method further comprises in response to said releasing of the data connection: starting a timer and operating the communication device in a first mode, the communication device being pageable by the network in the first mode. The method further comprises in response to expiry of the timer: operating the communication device in a second mode, the communication device not being pageable by the network in the second mode.

A device comprises control circuitry configured to perform a method. The method comprises releasing a data connection between a communication device and a network. The method further comprises in response to said releasing of the data connection: starting a timer and operating the communication device in a first mode, the communication device being pageable by the network in the first mode. The method further comprises in response to expiry of the timer: operating the communication device in a second mode, the communication device not being pageable by the network in the second mode.

For example, the device may be a control node of a core of the network, a UE, a BS, or a gateway node of a network.

By such techniques, the power consumption at the UE may be significantly reduced; while timely delivery of DL data to the UE may be facilitated.

It is to be understood that the features mentioned above and those yet to be explained below may be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a network and a UE connected to the network according to various examples.

FIG. 2 schematically illustrates a BS according to various examples. FIG. 3 schematically illustrates a control node according to various examples. FIG. 4 schematically illustrates a UE according to various examples.

FIG. 5 is a flowchart of a method according to various examples. FIG. 6 schematically illustrates different modes in which a UE can be operated according to various examples. FIG. 7 schematically illustrates the power consumption associated with different modes in which a UE can be operated according to various examples.

FIG. 8 is a signalling diagram of communication between a UE and a BS according to various examples.

FIG. 9 is a signalling diagram of communication between a UE and a BS according to various examples.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of embodiments is not to be taken in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described hereinafter or by the drawings, which are taken to be illustrative only.

The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling. A coupling between components may also be established over a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

Hereinafter, techniques of communicating between a UE and a network are described. In particular, techniques of wirelessly communicating between the UE and the network are described. The techniques described herein enable to reduce the power consumption of such communication.

In particular, hereinafter, techniques are described which enable to operate the UE in a mode in which it is not pageable by the network. For example, this mode may be implemented by the 3GPP-specified MICO mode. For sake of simplicity, such a mode in which the UE is not pageable will be referred to as non-pageable mode, hereinafter. By operating the UE in the non-pageable mode, the power consumption can be reduced. For example, when the UE is operated in the non-pageable mode, the network may refrain from transmitting paging signals to the UE. For example, when the UE is operated in the non-pageable mode, a receiver of the UE may be transitioned into a persistent sleep state. For example, the receiver of the UE may be unfit to receive any signals or data in this sleep state. In the sleep state, the modem of the UE may be turned off. In some examples, it could be possible that the receiver is sometimes turned on to monitor cell information for mobility purposes, e.g., in order to be able to transmit a tracking area update (TAU), e.g., according to some timing such as a fixed periodicity or according to some trigger event, e.g., when entering a new tracking area (TA). Other power saving benefits with the non-pageable mode is that the UE does not need to inform the network about its mobility. Operating the UE and the non-pageable mode may further include a node of the network, e.g., a core node of the network such as a mobility control node, maintaining a registration entry for the UE. Hence, operating the UE in the non-pageable mode may be distinct from a full detach of the UE from the network. Operating the UE in the non-pageable mode may not include detaching the UE from the network. For example, if the UE is detached from the network, there may be no registration entry maintained for the UE in a mobility management core network node such as the 3GPP Long Term Evolution (LTE) Mobile Management Entity (MME), or a 3GPP New Radio (NR) Access and Mobility Management Function (AMF). Such a registration entry may include an identity of the UE or a subscriber associated with the UE, e.g., an International Mobile Subscriber identity (IMSI) for a Temporary IMSI. The registration entry may facilitate re-establishment of a data connection between the BS of the network and the UE when the UE is not operated in the non-pageable mode, anymore: for example, security credentials may be determined based on the registration entry and may be used when establishing the data connection. Various techniques are based on the finding that, sometimes, it may be desirable to delay operation of the UE in transition to the non-pageable mode. For example, if reception of DL data is expected, e.g., DL data associated with a certain service provided by a PDN which is accessible from the network, then it may be desirable to delay operation of the UE in the non-pageable mode.

According to examples, a data connection between the UE and the network is released and in response to said releasing of the data connection, a timer is started. Furthermore, in response to releasing the data connection, the UE is operated in a first mode in which the UE is pageable by the network (idle mode). Then, in response to expiry of the timer, the UE is operated in the non-pageable mode. Thereby, by means of the timer, operation of the UE in the non-pageable mode can be delayed. This may facilitate reception of DL data by the UE. On the other hand, by releasing the data connection and, hence, operating the UE in the idle mode, the power consumption can already be reduced; in particular if compared to a scenario where the data connection is maintained for an extended duration of time.

Various techniques described herein are, thus, based on the finding that when the UE is operated in a non-pageable mode, the UE will only be able to receive DL data after transitioning back to connected mode out of its own initiative. In other words, a UE being operated in non-pageable mode is not listening for any paging signals from the network and it is completely up to the UE to re-establish a data connection to the network. Even for periodic registration, it is up to the UE to initiate the data connection, even if the periodicity of the re-registration is set by the core network, e.g., re-presented by a respective timer. When the UE requires connectivity or another service, it tries to connect to the network and when there is no more DL or UL data, then the UE begins to operate in idle mode and starts the timer. Then, for the UE being able to receive DL data from an application server of a PDN , according to examples, the UE is for an extended time duration operated in idle mode, before eventually transitioning to the non-pageable mode. If compared to scenarios where the UE is being continued to be operated in connected mode, a more power efficient solution is provided by continuing the UE to be operated in idle mode. FIG. 1 illustrates aspects with respect to the network 100. FIG. 1 illustrates further details with respect to the architecture of the network 100. The network 100 according to the example of FIG. 1 implements the 3GPP LTE architecture. According to 3GPP LTE, a wireless link 191 is defined in a radio access network (RAN). The wireless link 191 is defined between a BS in the form of an evolved node B (eNB) 101 a UE 102.

The illustration of the network 100 in FIG. 1 in the 3GPP LTE framework is for exemplary purposes only. Similar techniques can be readily applied to various kinds of 3GPP-specified architectures, such as Global Systems for Mobile Communications (GSM), Wideband Code Division Multiplex (WCDMA), General Packet Radio Service (GPRS), Enhanced Data Rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), Universal Mobile Telecommunications System (UMTS), and High Speed Packet Access (HSPA). For example, the techniques described herein may be applied to the 3GPP eNB-loT or MTC systems See, for example, 3GPP RP-161321 and RP- 161324. For example, the techniques described herein may be applied to the 3GPP NR systems, see 3GPP TS 23.501 V.0.3.1 . Furthermore, respective techniques may be readily applied to various kinds of non-3GPP-specified networks, such as Bluetooth, satellite networks, IEEE 802.1 1 x Wi-Fi technology, etc. The network 100 includes a CN 1 12. The CN 1 12 - the evolved packet core (EPC) in 3GPP LTE - is in communication with the RAN. The CN 1 12 includes a control layer and a data layer. The control layer includes control nodes such as the home subscriber server (HSS) 1 15, the mobile management entity (MME) 1 16, and the policy and charging rules function (PCRF) 1 19. The data layer includes gateway nodes such as the serving gateway (SGW) 1 17 and the packet data network gateway (PGW) 1 18.

The MME provides mobility control. For example, the MME 1 16 controls CN-initiated paging of the UE 102 if the respective UE is operated in idle mode. The MME 1 16 may keep track of a registration entry of the UE 102. The MME 1 16 may keep track of the particular mode in which the UE 102 is being operated. The MME 1 16 may keep track of the timing of a discontinuous reception (DRX) cycle of the UE 102. For example, the MME 1 16 may participate in establishing a data connection 160. The MME 1 16 may trigger transmission paging signals by the BS 101 . In the 3GPP NR context, the MME is referred to as AMF. The data connection 160 is established if the respective UE 102 operates in a connected mode. To keep track of the current state of the UE 102, the MME 1 16 sets the UE 102 to ECM connected or ECM idle. During ECM connected, a non-access stratum (NAS) connection is maintained between the UE 102 and the MME 1 16. The NAS connection implements an example of a mobility control connection.

The general functioning and purpose of the network nodes 1 15-1 19, 121 of the CN 1 12 is well known in the art such that a detailed description is not required in this context.

The data connection 160 is established between the UE 102 via the RAN and the data layer of the CN 1 12 and towards an access point 121 . For example, a connection with the Internet or another packet data network (PDN) 190 can be established via the access point 121 . To establish the data connection 160, it is possible that the respective UE 102 performs a random access (RACH) procedure, e.g., in response to reception of network paging or network wake-up. An application server of the PDN 190 may provide a service for which payload data is communicated via the data connection 160, e.g., UL payload data and/or DL payload data. The data connection 160 may include one or more bearers such as a dedicated bearer or a default bearer. The data connection 160 may be configured by the RRC layer, e.g., generally Layer 3 of the OSI model of Layer 2. Establishing of the data connection 160 may thus include OSI Network layer control signaling. By means of the data connection 160, time-frequency resources may be allocated on payload channels such as the Physical UL Shared Channel (PUSCH) and/or the Physical DL Shared Channel (PDSCH) to facilitate transmission of payload data. A control channel such as the Physical DL Control Channel (PDCCH) can facilitate transmission of control data. Also a Physical UL Control Channel (PUCCH) can be implemented.

FIG. 2 schematically illustrates the BS 101 . The BS 101 includes an interface 101 1 . For example, the interface 101 1 may include an analog front end and a digital front end. Also, communication with nodes of the network, e.g., of the core 1 12 may be possible via the interface 101 1 . The BS 101 further includes control circuitry 1012, e.g., implemented by means of one or more processors and software. For example, program code to be executed by the control circuitry 1012 may be stored in a non- volatile memory 1013. In the various examples disclosed herein, various functionality may be implemented by the control circuitry 1012, e.g.: operating the UE in different modes, e.g., a connected mode, an idle mode, and a non-pageable mode; transmitting paging signals to the UE; establishing a data connection between the UE and the network; and releasing a data connection between the UE and the network; etc.

FIG. 3 schematically illustrates a control node 109 of the network 100. For example, the control node 109 may correspond to the MME 1 16 or the AMF according to 3GPP NR. The control node 109 includes an interface 1091 . Via the interface 1091 , control circuitry 1092 of the control node 109 may communicate with one or more of the nodes of the network, e.g., with the BS 101 . For example, the control circuitry 1092 may be implemented by one or more processors and software. For example, program code to be executed by the control circuitry 1092 may be stored in a non-volatile memory 1093. In the various examples disclosed herein, various functionality may be implemented by the control circuitry 1092, e.g.: operating the UE in different modes, e.g., a connected mode, an idle mode, and a non-pageable mode; maintaining the registry of the UE when operating the UE in the respective modes; establishing a data connection between the UE and the network; and releasing a data connection between the UE and the network; etc.

FIG. 4 schematically illustrates the UE 102. The UE 102 includes an interface 1021 . For example, the interface 1021 may include an analog front end and the digital front end. The UE 100 to further includes control circuitry 1022, e.g., implemented by means of one or more processors and software. For example, program code to be executed by the control circuitry 1022 may be stored in a non-volatile memory 1023. In the various examples disclosed herein, various functionality may be implemented by the control circuitry 1023, e.g.: operating the UE 102 in different modes, e.g., a connected mode, an idle mode, and a non-pageable mode; receiving paging signals from the network; establishing a data connection between the UE 102 and the network; and releasing a data connection between the UE and the network; etc.

For example, the UE 102 may be one of a smart phone, a cellular handheld phone, a laptop, a smart meter, a sensor, an actuator, a MTC device, etc. FIG. 5 is a flowchart of a method according to various examples. For example, the method according to FIG. 5 may be executed by the control circuitry 1012 of the BS 101 , and/or the control circuitry 1092 of the control node 109, and/or the control circuitry 1022 of the UE 102.

First, in 2001 - which is an optional step (dashed line in FIG. 5) -, a timer is set. Setting a timer may correspond to defining properties of the timer such as an initial value and a final value of the timer, a time increment, a timeout duration, etc. Hence, in other words, in 2001 , the timer value may be pre-configured, i.e., set prior to the point in time at which the timer is started later on. For example, the timer may be implemented by the BS 101 . Alternatively or additionally, the timer may be implemented by the UE 102.

The time increment may be set in accordance with a timing of a DRX cycle; for example, the time increment may correspond to the periodicity of the DRX cycle. Then, the timeout duration may correspond to an integral multiple of periods of the DRX cycle.

Setting of the timer may be based on various decision criteria. Examples of decision criteria offsetting the time include a latency associated with the service provided by a PDN to a UE; and a value indicated by a control message communicated between the UE and the network.

For example, the timer may be set based on control signaling exchanged between the UE and the network. For example, a timer setting may be negotiated between the UE and the network. For example, a timer setting may be determined at the network - e.g., at the BS - and then the UE may be informed accordingly. For example, the timer setting may be communicated in a control message such as during establishment of a data connection or during release of a data connection. For example, the time timer setting may be communicated in an Attach or RRC connection setup message. Here, explicit or implicit indications of the timer setting may be signaled.

For example, it may be possible that generally the capability of the UE of supporting a respective timer is indicated to the network. For example, the UE may indicate if it generally supports the timer; in the affirmative, the timer setting may be provided by the network to the UE. It could also be possible that if the UE indicates support of the timer, a fixedly set timer setting are used.

All such examples above describe a dynamic setting of the timer.

In some examples, the timer may be fixedly set, e.g., to some specification. Respective control data may be provided in non-volatile memory. Then, 2001 does not need to be executed. Here, it may also not be required to implement control signaling between the network and the UE. This corresponds to a static setting of the timer.

Next, in 2002, it is checked whether data is waiting to be communicated between the UE and the network. For example, in 2002 it may be checked whether UL data is waiting to be transmitted and/or received (communicated). Alternatively or additionally, in 2002, it may be checked whether DL data is waiting to be communicated. For example, in 2002 it may be checked whether control data and/or payload data is waiting to be communicated. For example, in 2002, the filling level of one or more transmit buffers may be checked or monitored.

If, at 2002, it is judged that no more data is waiting to be communicated, then, in 2003, the data connection is released. 2002 is again optional. In particular, there may be other the decision criteria for releasing the data connection in 2003. Alternative or additional decision criteria for releasing the data connection in 2003 would be communicating of a connection release control message, e.g., from the network to the UE and/or expiry of a further timer.

In response to releasing the data connection in 2003, next, in 2004, the timer is started. In other words, the timer is initialized and, subsequently, moves in certain increments from its start value to its stop value, thereby defining a timeout duration. In 2004, the timer may be started based on the settings provided in the optional block 2001 .As such, the timer setting is pre-configured when executing 2004, i.e., configured some time before executing 2004.

In 2005 and, hence, also in response to releasing the data connection in 2003, the UE is operated in the first mode. For example, the UE may be operated in an idle mode in 2005, because the data connection has been released and, hence, the UE is not operated in connected mode, anymore. With the data connection having been released, it may not be possible to directly transmit higher-layer data such as Layer 2 or Layer 3 control data or payload data.

Operating the UE in the idle mode in 2005 may include keeping a respective registration entry at the network, and/or communicating paging signals in accordance with certain properties of the idle mode such as, e.g., a DRX cycle, and/or transitioning a receiver of the UE into a power-save state, etc. Hence, operating the UE in the idle mode in 2005 may involve actions at the BS, the control node of the network, and/or the UE.

In 2005A - which is an optional step -, paging may be executed. The UE is pageable when being operated in the first mode. If paging is executed in successful, at 2008 the data connection is re-established.

Otherwise, in 2006, it is checked whether the timer - which has been started in 2004 - has expired. If this is not the case, then the UE is continuously operated in the first mode by re-executing 2005. Otherwise, the method commences with 2007.

In 2007, the UE is operated in a second mode, i.e., in response to expiry of the timer. For example, the second mode may be a non-pageable mode.

Operating the UE in the non-pageable mode in 2007 may include keeping a respective registration entry at the network, and/or prohibiting communication of paging signals, and/or transitioning the receiver of the UE into a persistent sleep state, etc. Hence, operating the UE in the non-pageable mode in 2007 may involve actions at the BS, the control node of the network, and/or the UE.

The non-pageable mode may be implemented by 3GPP NR MICO mode, according to the examples described herein. At 2008 - which is again an optional step -, the data connection is re-established. There may be different trigger criteria for this, e.g., periodic re-registration of the UE according to some further timer, or a need for transmitting UL data. The order of the blocks in FIG. 5 may vary in different examples. For example, instead of setting the timer in 2001 before releasing the data connection in 2003, the timer could be set at 2003. For example, a timer setting may be communicated from the network to the UE in 2003. For example, the timer setting such as the timeout duration may be communication in a release message of the data connection.

FIG. 6 illustrates aspects with respect to different modes 301 - 304 in which the UE 102 can be operated.

In connected mode 301 , the data connection 160 is set up. For example, a default bearer and optionally one or more dedicated bearers may be set up between the UE 102 and the network 100.

In order to reduce the power consumption, it is then possible to transition from the connected mode 301 to a connected mode 302 which employs a DRX cycle (Connected mode DRX). The DRX cycle includes on durations and off durations. During the off durations, the interface 1021 is unfit to receive data; e.g., the analog and/or digital frontend may at least be partially powered down. The timing of the DRX cycle is synchronized between the UE 102 and the BS 101 such that the BS 101 can align any DL transmission with the on durations of the connected mode DRX cycle. The data connection 160 is maintained established in mode 302. The data connection 160 is not released.

To achieve a further power reduction, it is possible to transition into idle mode 303. The idle mode 303 is, again, associated with an idle mode DRX cycle of the UE 102. However, during the on durations of the DRX cycle in idle mode 303, the interface 1021 is only fit to receive paging signals. For example, this may help to restrict the bandwidth that needs to be monitored by the during the on durations of the DRX cycles in idle mode 303. This may help to further reduce the power consumption - e.g., if compared to the connected mode 302. FIG. 6 illustrates a non-pageable mode 304. Operating the UE 102 in the non-pageable mode may include switching a receiver of the interface 1021 of the UE 102 to a persistent sleep state. Thus, when transitioning from the idle mode 303 to the non- pageable mode 304 - which may be in response to the expiry of a respective timer - the receiver of the interface 1021 of the UE 102 may be transitioned to the persistent sleep state. Here, there may be no on durations of a DRX cycle such that there are no paging occasions and the network 100 may not be able to reach the UE 102. Hence, operating the UE 102 in the non-pageable mode may include preventing transmission of paging signals to the UE 102. A DRX cycle is not employed.

The UE may not be fully detached when being operated in the non-pageable mode 304. Hence, operating the UE 102 in the non-pageable mode 304 may include the control node 109 maintaining a registration entry for the UE 102. Then, when transitioning from the non-pageable mode 304 to the connected mode 301 , a random access message may be transmitted by the UE 102 and received by the BS 101 . In response to the communicating of the random access message, it is possible to (re-) establish the data connection 160 between the UE 102 and the network 100. Said establishing may be based on the registration entry maintained in the control node 102 while operating the UE 102 in the non-pageable mode 304. For example, security credentials for the data connection 160 may be determined based on an identity of the UE 102 and/or a subscriber associated with the UE 102. This facilitates fast establishment of the data connection. FIG. 7 illustrates aspects with respect to the connected mode 301 , the idle mode 303, and the non-pageable mode 304. FIG. 7, furthermore, illustrates the power consumption 331 - 333 associated with operating the UE 102 in the connected mode 301 , the idle mode 303, and the non-pageable mode 304, respectively. Initially, the UE 102 is operated in the connected mode 301 . Here, a DRX cycle is not employed. Hence, the receiver of the interface 1021 of the UE 102 is in a persistent active state. This is associated with a comparably large power consumption 331 . Then, there is no more data to be communicated between the UE 102 and the network 100, and the UE 102 is, subsequently, operated in the idle mode 303. Here, the DRX cycle including on durations 371 and off durations 372 is employed. During the on durations 371 , the receiver of the interface 1021 is configured to listen for paging signals from the BS 101 . Thus, the receive bandwidth of the receiver may be restricted to the respective control channel carrying the paging signals; the receive bandwidth employed in the idle mode 303 may be smaller than the receive bandwidth employed in the connected mode 301 . In particular, it may not be required that the receive bandwidth also includes other channels not carrying paging signals. Furthermore, certain functionality of the interface 1021 not required for receiving paging signals may be shut down. Thereby, the power consumption 332 during the on durations 371 of the DRX cycle is lower than the power consumption 331 experienced during connected mode 301 . When transitioning from the connected mode 301 to the idle mode 303, the data connection 160 between the UE 102 in the network 100 is released. In response to said releasing of the data connection 160, a timer 3081 is started. For example, a timer setting may be included in the release message. In response to expiry of the timer 3081 , the UE 102 is operated in the non-pageable mode 304. Here, a comparably low power consumption 333 is observed due to the receiver of the interface 1021 having been transitioned to a persistent sleep state 3099.The sleep state 3099 thus may characterize the operation of the receiver hardware of the UE; while the non-pageable mode 304 may relate to the operation of the UE with respect to the network. FIG. 8 illustrates aspects with respect to communication between the UE 102 and the BS 101 .

First, at 3001 , a DL control message 4001 is transmitted by the BS 101 and received by the UE 102. The control message 4001 is indicative of a timer setting of the timer 3081 . For example, the control message 4001 may be indicative of the timeout duration of the timer 3081 . It is then possible that the timer 3081 is set in accordance with the timer setting (cf. block 2001 in FIG. 5). Alternatively or additionally to the control message 4001 being indicative of a timer setting, the control message 4001 could also be indicative of whether the timer 3081 is to be implemented at all. In other words, the control message 4001 could also be indicative of whether there is a direct transition from the connected mode 301 or the connected mode 302 to the non-pageable mode 304 (cf. dashed arrow in FIG. 6); or rather a timer-controlled transition from the connected mode 301 of the connected mode 302 to the non-pageable mode 304 via the idle mode 303. Thus, operating of the UE 102 in the idle mode 303 may be selectively executed depending on the control message 4001 .

While in the example of FIG. 8 a scenario is illustrated where a single DL control message 4001 is communicated from the BS 101 to the UE 102, in other examples, multiple control messages may be communicated. For example, a bidirectional negotiation of the timer setting and/or execution of the time-controlled idle mode 303 when transitioning to the non-pageable mode 304 could be implemented.

Then, at 3002, UL data 4002 is transmitted by the UE 102 and received by the BS 101 . The UL data can be associated with a service provided by the PDN 190. For example, the service may be one of a music streaming service; a web browsing service; a video streaming service; a messaging service; an e-mail service; etc.

The UL data 4002 is transmitted using the data connection 160. The data connection 160 has been established previously (FIG. 8 does not illustrate the establishment of the data connection 160 prior to communication of the UL data 4002).

For example, the UL data 4002 may include a request associated with the service. For example, this service request may request DL data from the application server at the PDN 190. Then, there is no more data to communicate; i.e., there is no DL data and no UL data. The transmit buffers at the UE 102 and the BS 101 may be empty. A timer 3082 is started in response to transmitting the UL data 4002. After expiry of the timer 3082, the data connection 160 is released. For example, a timeout duration of the timer may be below 1 s, optional below 10 ms, optionally below 2 ms. The timer 3082 may be implemented at the BS 101 and/or at the UE 102. Depending on where the timer 3082 is implemented, different scenarios for releasing the data connection 160 are conceivable. In the particular example of FIG. 8, a DL connection release message 4003 is transmitted by the BS 101 and received by the UE 102. The release message 4003 may include a timer setting for the timer 3081 , e.g., a timeout duration.

In response to releasing the data connection 160, the UE 102 is operated in the idle mode 303. Several paging occasions corresponding to the on durations 371 of the respective DRX cycle are illustrated in FIG. 8. After a while, the BS 101 transmits a paging signal 4004, at 3004. The paging signal 4004 is communicated in accordance with the DRX cycle, i.e., during an ON duration 371 . The paging signal 4004 is received by the UE 102 which then participates in a random access procedure at 3005, together with the BS 101 . For example, participating in the random access procedure at 3005 may include the UE 102 transmitting a random access message such as a random access preamble and receiving one or more temporary identifiers from the BS 101 . The random access procedure may include the UE 102 transmitting on shared resources of a random access channel. Here, collision with other UEs attempting to connect to the network 100 may occur.

After this, a further data connection 160 is established in a connection setup 3006. This may include higher-level control signaling, e.g., Layer 3 control signaling. For example, certain security credentials associated with the data connection 160 established at 3006 may be determined based on the registration entry for the UE 102 maintained in the network 100 while the UE 102 has been operated in the idle mode 303.

Then, finally, in response to communicating of the paging signal 4004, DL data 4005 is transmitted by the BS 101 and received by the UE 102 at 3007. In the example of FIG. 8, the DL data 4005 is associated with the same service as the UL data 4002; but may, generally, also be associated with a different service. For example, the DL data 4005 may be provided by the application server of the PDN 190 to the network 100 in response to a request or query included in the UL data 4002. For example, arrival of the DL data 4005 at the network 100 - e.g . in a transmit buffer of the BS 101 or at a gateway node such as the SGW 1 17 or the PGW 1 18 - may trigger transmission of the paging signal 4004 at 3004. For example, the DL data 4005 may be prompted by the UL data 4002. For example, a respective request associated with the service and included in the UL data 4002 may prompt the DL data 4005.

As illustrated in FIG. 8, in response to releasing the data connection 160 at 3003, the timer 3081 is started. By means of the timer 3081 , transition of the UE 102 to the non- pageable mode 3005 is delayed. In particular, this delay is dimensioned such that the UE 102 is still being operated in the idle mode 303 - in which it is pageable by the network 100 - when the DL data 4005 arrives at the network 100, e.g., at a transmit buffer of the BS 101 . Generally, it would be possible that the timer 3081 is set based on the latency associated with the service, which services associated with the UL data 4002 and the DL data 4005. For example, this may include monitoring the time durations between communication of the UL data 4002 and communication of the DL data 4005 at a plurality of occasions and setting the timer 3081 accordingly. Certain reference values for the latency may be stored at the network 100 and the timer setting may be appropriately provided by means of the control message 4001 . Such techniques enable timely delivery of the DL data 4005. As will be appreciated, the timer 3081 may hence be set service specific.

Also, the timer 3081 may be implemented at the BS 101 and/or the UE 102. For example, if the timer 3081 is implemented at the BS 101 , but not at the UE 102, the BS 101 may transmit a command during an on duration 371 while the UE 102 is being operated in the idle mode 303, which command instructs the UE 102 to transition to the non-pageable mode 301 . If the timer 3081 is implemented at the UE 102, but not at the BS 101 , the UE 102 may inform the BS 101 about transitioning to the non- pageable mode 301 by a respective control message. In other examples, it is possible that the timer 3081 is implemented at, both, the BS 101 and the UE 102; then respective control signaling is not required.

FIG. 9 illustrates aspects with respect to communication between the UE 102 and the BS 101 . FIG. 9 generally corresponds to the example of FIG. 8. For example, 3021 - 3023 correspond to 3001 - 3003, respectively. However, in the example of FIG. 9, there is no DL data 4005 to be communicated from the BS 101 to the UE 102 prior to expiry of the timer 3081 . Hence, in response to expiry of the timer 3081 , the UE 102 is operated in the non-pageable mode 304. Eventually, a random access is performed at 3024, e.g., because UL data 4002 is scheduled for transmission at the UE 102. A connection setup is then performed at 3025 and at 3026 the UL data 4002 that triggered the random access at 3024 is communicated.

Summarizing, above techniques have been described in which the UE can transition to idle mode, e.g., quickly after transmitting UL data. Then, in idle mode, the UE is configured to listening for paging signals from the network for a certain predefined time duration which is implemented in examples by a timer. Hence, in idle mode, conventional paging procedures can be used in order to trigger re-establishment of a data connection once DL data that may be associated with the UL data previously transmitted is scheduled for transmission.

In some examples, it initial attach or other signaling occasions, the UE indicates its capability and/or preference of implementing such a timer-controlled idle mode before transitioning to non-pageable mode. Alternatively or additionally, such capability and/or preference may be indicated to the network when the UE transitions to connected mode, i.e., when establishing a data connection.

The timer may be implemented by the UE and a network node, e.g., the BS or another control node of the core network. For example, a time increment could be re-presented by a number of on durations of the DRX cycle. For example, if the UE is configured with a periodicity of on durations of the DRX cycle corresponding to 2.56 seconds, the timeout duration of the timer could be 10x2.56 second = 25.6 second. The timer value should be known by the network and UE when the timer starts in 2004. If the value is not fixed/standardized, then it could be agreed between the network and the UE, e.g., in block 2001 and/or block 2003 (cf. FIG. 5).

With such a mechanism presented above, the UE is only required to implement an extra timer and the core network can be aware that after expiry of the timer it is not possible to page or otherwise reach the UE. The benefit is that the network is able to switch the UE to different power-saving mechanisms very fast, long time before a response is guaranteed from an application server; and, nonetheless, the UE is able to utilize the non-pageable mode and switch off a receiver completely during the majority of the time. In the various examples described herein, the can be different scenarios implemented for transitioning the UE to the non-pageable mode. In a first example, the UE may register with the network and request application of the non-pageable mode until further notice. The network may accept or reject the request. In a second example, the UE may register with the network and may also provide capability information. After that, every time the UE enters the connected mode, the UE may include the preference to use the timer-controlled idle mode prior to transitioning to the non-pageable mode and the network may grant or reject the request. When the UE enters the idle mode, the timer is started, e.g., at both the core network and the UE. Then, the UE is reachable by paging until expiry of the timer; this can facilitate provision of DL data that may be provided as a response to previous UL data from an application server of a PDN. In response to expiry of the timer, the UE does not listen for paging any longer. I.e., the UE may not be reachable by the network, anymore. There may be some periodic registration implemented by a respective further timer. Except for such periodic registration, the UE may turn off the receiver completely, i.e., transition the receiver to an persistent in active state. If there is UL data scheduled for transmission at the UE, the UE may perform a random access procedure.

Although the invention has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the appended claims.

For example, while various examples have been described in connection with the 3GPP LTE network architecture, similar techniques may be readily employed for the 3GPP NR architecture.

Claims

1 . A method, comprising:

- releasing a data connection (160) between a communication device (102) and a network (100),

- in response to said releasing of the data connection (160): starting a timer (3081 ) and operating the communication device (102) in a first mode (303), the communication device (102) being pageable by the network (100) in the first mode (303), and

- in response to expiry of the timer (3081 ): operating the communication device

(102) in a second mode (304), the communication device (102) not being pageable by the network (100) in the second mode (304).

2. The method of claim 1 , further comprising:

- while operating the communication device (102) in the first mode (303): communicating a paging signal (4004) from the network (100) to the communication device (102) in accordance with a discontinuous reception cycle implemented by the communication device (102) in the first mode (303).

3. The method of claims 1 or 2, further comprising:

- communicating uplink data (4002) from the communication device (102) to the network (100),

wherein the data connection (160) is released after said communicating of the uplink data (4002).

4. The method of claims 2 and 3, further comprising:

- in response to said communicating of the paging signal (4004): communicating downlink data (4005) from the network (100) to the communication device (102), wherein the downlink data (4005) and the uplink data (4002) are associated with a common service provided by a packet data network (100) accessible from the network (100).

5. The method of claim 4, further comprising:

- setting the timer (3081 ) based on a latency associated with the service.

6. The method of any one of the preceding claims, further comprising:

- communicating, between the communication device (102) and the network (100), at least one control message (4001 ) which is indicative of a timer setting, and

- setting the timer (3081 ) in accordance with the timer setting.

7. The method of any one of the preceding claims, further comprising:

- communicating, between the communication device (102) and the network (100), at least one at least one control message (4001 ),

wherein said operating of the communication device (102) in the first mode (303) is selectively executed depending on the at least one control message.

8. The method of any one of the preceding claims, further comprising:

- in response to the expiry of the timer (3081 ): transitioning a receiver of the communication device (102) to a persistent sleep state (3099).

9. The method of any one of the preceding claims, further comprising:

- a node of the network (100) maintaining a registration entry for the communication device (102) when operating the communication device (102) in the first mode (303) and in the second mode (304).

10. The method of claim 9, further comprising:

- after the expiry of the timer (3081 ): communicating a random-access message from the communication device (102) to the network (100), and - in response to communicating the random-access message: establishing a further data connection (160) between the communication device (102) and the network (100),

wherein the further data connection (160) is established based on the registration entry.

1 1 . The method of any one of the preceding claims, further comprising:

- implementing the timer at the communication device (102) and/or at the network (100).

12. A device (101 , 102, 1 16, 1 17, 1 18) comprising control circuitry configured to:

- release a data connection (160) between a communication device (102) and a network (100),

- in response to said releasing of the data connection (160): start a timer (3081 ) and operate the communication device (102) in a first mode (303), the communication device (102) being pageable by the network (100) in the first mode (303), and

- in response to expiry of the timer (3081 ): operate the communication device

13. The device (101 , 102, 1 16, 1 17, 1 18) of claim 12,

wherein the control circuitry is configured to perform the method of any one of the preceding claims 1 - 1 1 .