WO2019232780A1

WO2019232780A1 - Method and apparatus for data transmission

Info

Publication number: WO2019232780A1
Application number: PCT/CN2018/090411
Authority: WO
Inventors: Jingrui TAO; Bo Zhang; Zhiqiang LONG
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2018-06-08
Filing date: 2018-06-08
Publication date: 2019-12-12

Abstract

Method and apparatus for data transmission are disclosed. A method may comprise: receiving a first message terminated at a user equipment (UE) or originated from the UE, wherein the UE uses a power saving mode or discontinuous reception. The method may further comprise transmitting to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

Description

METHOD AND APPARATUS FOR DATA TRANSMISSION

Technical Field

Embodiments of the disclosure generally relate to communication, and, more particularly, to methods and apparatus for data transmission

Background

Many Cellular Internet of Things (CIoT) applications need to run for years over batteries and reduce overall energy consumption. To reduce its power consumption, a CIoT device such as a user equipment (UE) may adopt a power saving mechanism, e.g. power saving mode (PSM) and extended idle mode discontinuous reception (DRX) . A UE in PSM is not immediately reachable for mobile terminated (MT) services. A UE using PSM is available for the MT services during a time that is in a connected mode and for a period of an active time that is after the connected mode. Depends on the DRX cycle value, a UE using extended idle mode DRX has to accept a corresponding latency in both mobile originated (MO) and MT communication. When a server such as a service capability server (SCS) or application server (AS) expects low latency and efficient MT communication with a UE, it is advantage to know UE reachability information and transmit a MT request when the UE is reachable.

Non-Internet Protocol (IP) data delivery (NIDD) is a feature of SCEF (Service Capability Exposure Function) in 3rd Generation Partnership Project (3GPP) . When a UE using PSM is temporally unreachable and SCEF receives MT NIDD request from SCS/AS, SCEF may buffer the MT Non-IP Data and retransmission it after the UE being reachable based on the configuration or request from SCS/AS. A mobility management entity (MME) or a serving general packet radio service (GPRS) support node (SGSN) transmits a UE reachability indication to the SCEF by a mobile originated event like mobile originated data transfer request or signaling, e.g. a T6a/b connection establishment or update. Once the SCEF receives the UE reachability indication from the MME/SGSN, it starts to retransmit the buffered MT Non-IP Data to UE through the T6a/b connection and transmits a MT submit response to the SCS/AS to notify the delivery result.

Event monitoring is another feature of SCEF. 3GPP defines UE reachability event monitoring procedures to report the UE reachability information to SCS/AS if SCS/AS subscribed the monitoring service.

Summary

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

According to a first aspect of the disclosure, it is provided a method in a first network element. The method may comprise: receiving a first message terminated at a user equipment, UE, or originated from the UE. The method may further comprise transmitting to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

In an embodiment, the availability time comprises at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable.

In an embodiment, the first message comprises Non-Internet Protocol, Non-IP, data.

In an embodiment, the first message is terminated at the UE and is a Non-Internet Protocol Data Delivery, NIDD, submit request received from the second network element, and/or the second message is a NIDD submit response message.

In an embodiment, the first message is originated from the UE, and/or the second message is a Non-Internet Protocol Data Delivery, NIDD, submit request.

In an embodiment, the first network element is a mobility management entity, MME, or a serving general packet radio service, GPRS, support node , SGSN, and/or the second network element is a service capability exposure function, SCEF.

According to a second aspect of the disclosure, it is provided a method in a second network element. The method may comprise: receiving from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable. The method may further comprise transmitting to a third network element a third message including the availability time of the UE.

In an embodiment, the method may further comprise performing data delivery terminated at the UE based on the availability time of the UE.

In an embodiment, the method in a second network element may comprise receiving Non-Internet Protocol data terminated at the UE from the third network element; and transmitting a first message terminated at the UE comprising the Non-Internet Protocol data to the first network element.

In an embodiment, the Non-Internet Protocol data is included by the third network element in a Mobile Terminated MT Non-Internet Protocol data delivery , NIDD, submit request, the first message is a NIDD submit request, and the second message is a NIDD submit response message and/or the third message is a MT NIDD submit response message.

In an embodiment, the second message is a Non-Internet Protocol data delivery, NIDD, submit request comprising Non-Internet Protocol data originated from the UE and/or the third message is a Mobile Originated, MO, NIDD indication message comprising the Non-Internet Protocol data originated from the UE.

In an embodiment, the first network element is a mobility management entity, MME, or a serving general packet radio service, GPRS, support node, SGSN, the second network element is a service capability exposure function , SCEF, and/or the third network element is a service capability server, SCS, or application server, AS.

According to a third aspect of the disclosure, it is provided a method in a third network element. The method may comprise receiving from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.

In an embodiment, the method in a third network element may comprise transmitting Non-Internet Protocol data terminated at the UE to the second network element, wherein the Non-Internet Protocol data is included in a Mobile Terminated, MT, Non-Internet Protocol Data Delivery, NIDD, submit request and/or the third message is a MT NIDD submit response message.

In an embodiment, the third message is a Mobile Originated, MO, Non-Internet Protocol Data Delivery, NIDD, indication message comprising Non-Internet Protocol data originated from the UE..

In an embodiment, the second network element is a service capability exposure function, SCEF, and/or the third network element is a service capability server, SCS, or application server, AS.

According to a fourth aspect of the disclosure, it is provided an apparatus in a first network element. The apparatus may comprise: a processor; and a memory, the memory containing instructions executable by the processor, whereby the apparatus is operative to: receive a first message terminated at a user equipment, UE, or originated from the UE; and transmit to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

According to a fifth aspect of the disclosure, it is provided an apparatus in a second network element. The apparatus may comprise: a processor; and a memory, the memory containing instructions executable by the processor, whereby the apparatus is operative to: receive from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable; and transmit to a third network element a third message including the availability time of the UE.

According to sixth aspect of the disclosure, it is provided an apparatus in a third network element. The apparatus may comprise: a processor; and a memory, the memory containing instructions executable by the processor, whereby the apparatus is operative to receive from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.

According to a seventh aspect of the disclosure, it is provided a computer program product. The computer program product comprises instructions which when executed by at least one processor, may cause the at least one processor to receive a first message terminated at a user equipment, UE, or originated from the UE; and transmit to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

According to an eighth aspect of the disclosure, it is provided a computer program product. The computer program product comprises instructions which when executed by at least one processor, may cause the at least one processor to receive from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable; and transmit to a third network element a third message including the availability time of the UE.

According to a ninth aspect of the disclosure, it is provided a computer program product. The computer program product comprises instructions which when executed by at least one processor, may cause the at least one processor to receive from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.

According to tenth aspect of the disclosure, it is provided a system. The system may comprise a first network element comprising an apparatus according to the fourth aspect of the present disclosure; a second network element comprising an apparatus according to the fifth aspect of the present disclosure; and a third network element comprising an apparatus according to the sixth aspect of the present disclosure.

Some embodiments of the disclosure may provide an efficient and timely way to pass the availability time of a device (such as UE) such as “Maximum-UE-Availability-Time” information to an entity such as IoT application server within a data deliveray procedure such as the NIDD procedure. The cost of UE reachability event monitoring subscription and reporting procedures may be saved.

These and other objects, features and advantages of the disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which are to be read in connection with the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is a flow chart depicting an existing mobile terminated NIDD procedure of 3GPP;

Fig. 2 is a flow chart depicting a mobile terminated NIDD procedure according to an embodiment of the present disclosure;

Fig. 3 is a flow chart depicting a mobile terminated NIDD procedure with retransmission according to an embodiment of the present disclosure;

Fig. 4 is a flow chart depicting a mobile originated NIDD procedure according to an embodiment of the present disclosure;

Fig. 5 is a flow chart depicting a method in a first network element according to an embodiment of the present disclosure;

Fig. 6a is a flow chart depicting a method in a second network element according to an embodiment of the present disclosure;

Fig. 6b is a flow chart depicting a method in a second network element according to another embodiment of the present disclosure;

Fig. 7a is a flow chart depicting a method in a third network element according to an embodiment of the present disclosure;

Fig. 7b is a flow chart depicting a method in a third network element according to another embodiment of the present disclosure;

Fig. 8 is a block diagram illustrating an apparatus in a first network element according to an embodiment of the disclosure;

Fig. 9 is a block diagram illustrating an apparatus in a second network element according to another embodiment of the disclosure; and

Fig. 10 is a block diagram illustrating an apparatus in a third network element according to another embodiment of the disclosure.

Detailed Description

For the purpose of explanation, details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed. It is apparent, however, to those skilled in the art that the embodiments may be implemented without these specific details or with an equivalent arrangement.

As used herein, the term “wireless network” refers to a network following any suitable communication standards, such as LTE-Advanced (LTE-A) , LTE, Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , and so on. Furthermore, the communications between a terminal device and a network device in the wireless network may be performed according to any suitable generation communication protocols, including, but not limited to, Global System for Mobile Communications (GSM) , Universal Mobile Telecommunications System (UMTS) , Long Term Evolution (LTE) , and/or other suitable, and/or other suitable the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) communication protocols such as new radio (NR) , wireless local area network (WLAN) standards, such as the IEEE 802.11 standards; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax) , Bluetooth, and/or ZigBee standards, and/or any other protocols either currently known or to be developed in the future.

The term “network device/element” refers to a device/element in a wireless communication network via which a terminal device/UE accesses the network and receives services therefrom. In the wireless communication network, the network device may refer to a base station (BS) , an access point (AP) , radio network controllers (RNCs) or base station controllers (BSCs) , Mobility Management Entity (MME) , Serving GateWay (SGW) , Packet Data Network GateWay (PGW) , Policy and Charging Rules Function (PCRF) , Home Subscriber Server (HSS) or any other suitable device in the wireless communication network.

The term “UE” refers to any end device that can access a wireless network and receive services therefrom. By way of example and not limitation, the UE refers to a mobile terminal, a terminal device, or other suitable devices. The UE may be, for example, a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, portable computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, wearable terminal devices, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device” , “terminal” , “user equipment” and “UE” may be used interchangeably. As one example, a terminal device may represent a UE configured for communication in accordance with one or more communication standards promulgated by the 3rd Generation Partnership Project (3GPP) , such as 3GPP’s GSM, UMTS, LTE, and/or 5G standards. As used herein, a “user equipment” or “UE” may not necessarily have a “user” in the sense of a human user who owns and/or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and/or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the wireless network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

The terminal device may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, and may in this case be referred to as a D2D communication device.

As yet another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band Internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

As used herein, a downlink (DL) transmission refers to a transmission from the network device to a terminal device, and an uplink (UL) transmission refers to a transmission in an opposite direction.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be liming of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

It is noted that though the embodiments below are mainly described in the context of IoT, they are not limited to this but can be applied to any suitable network that can benefit from the embodiments as described herein. In addition, though the embodiments below are mainly described in the context of a NIDD data deliveray procedure, they are not limited to this but can be applied to any suitable data (such as IP data) deliveray procedure that can benefit from the embodiments as described herein.

Fig. 1 is a flow chart depicting an existing mobile terminated NIDD procedure of 3GPP. As shown in Fig. 1, if SCS/AS has downlink Non-IP data to transmit to the UE, the SCS/AS transmits a MT NIDD Submit Request at step 102.

At step 104, the SCEF checks a NIDD configuration for the UE and evolved packet core (EPS) bearer context based on access point name (APN) associated with the NIDD configuration and a user identity (ID) . If the SCS/AS is authorized to transmit MT NIDD requests and that the SCS/AS has not exceeded the quota (e.g. 200 bytes in 24 hours) or rate (e.g. 10 bytes/hour) of data submission to the SCEF EPS bearer, the flow continues with step 106.

At step 106, the SCEF transmits a NIDD submit request message toward MME/SGSN.

At step 108, MME/SGSN is aware of the UE being temporarily unreachable, or if MME/SGSN knows that the UE is not scheduled to be reachable within a SCEF wait time, while using power saving functions e.g. UE power saving mode or extended idle mode DRX, then the MME/SGSN may transmit a NIDD submit response message including parameters such as cause and requested re-transmission time towards the SCEF. The cause parameter indicates that Non-IP data was not delivered to the UE, as the UE is temporarily not reachable due to power saving but the MME/SGSN will notify the SCEF when the MME/SGSN determines the UE is reachable. The MME/SGSN sets a Not Reachable for NIDD flag in EPS Mobility Management (EMM) context for this UE and stores a corresponding SCEF address. If the Maximum Re-transmission Time was included in the NIDD submit request, the MME may indicate, in the parameter requested re-transmission time, the time when the SCEF is expected to re-transmit the DL data to the currently unreachable UE.

At step 110, the SCEF transmits a MT NIDD submit response to the SCS/AS informing of results received from the MME/SGSN. If the SCEF receives from the MME/SGSN a cause value indicating that the UE is temporarily not reachable due to power saving, the SCEF can buffer the Non-IP data requested at step 106 based on the configuration and proceed to step 112.

At step 112, UE becomes reachable, e.g. when coming out of PSM mode and perform a tracking area update (TAU) or routing area update (RAU) .

When the MME/SGSN detects that the UE is reachable (e.g. when coming out of PSM mode by performing TAU/RAU, when initiating MO communication etc. ) , or when the UE is about to become reachable (e.g. extended idle mode DRX cycle expiring, the MME/SGSN anticipating MO communication pattern for the UE etc. ) , and the MME/SGSN has the Not Reachable for NIDD flag set, then the MME/SGSN transmits a NIDD submit indication message including user identity towards the SCEF at step 114.

At step 116, if the Non-IP data has not been purged, the SCEF transmits a NIDD submit request message including parameters such as User Identity, EPS Bearer ID, SCEF ID, Non-IP data, SCEF wait Time, Maximum Re-transmission time toward MME/SGSN.

At step 118, if required, the MME/SGSN pages the UE and delivers the Non-IP data to the UE using data transfer via a MME procedure as described in clause 5.3.4B. 3 of TS 23.401 of 3GPP or the SGSN procedure as described in clauses 9.3 and 9.6 of TS 23.060 of 3GPP, which are incorporated herein by reference in their entirety. Depending on an operator configuration, the MME/SGSN may generate the necessary accounting information required for charging.

At step 120, if the MME/SGSN could initiate step 118, then the MME/SGSN transmits a NIDD submit response (cause) message without Maximum-UE-Availability-Time information element towards the SCEF acknowledging the NIDD submit request received from SCEF in step 116.

At step 122, the SCEF transmits a MT NIDD submit response with NIDD submit result but without Maximum-UE-Availability-Time information element to the SCS/AS.

At step 124, the UE becomes unreachable again, e.g. enters the PSM mode.

At step 126, the SCS/AS doesn’t know that the UE is unreachable and keep transmitting the MT NIDD submit request to the SCEF. The SCEF &MME/SGSN repeat steps 104-110.

For SCS/AS, according to the existing NIDD procedures, although it can implicitly know a UE being reachable by a MT submit response or a MO request from SCEF, SCEF does not pass the Maximum-UE-Availability-Time information element in both messages to SCS/AS such that SCS/AS doesn’t know how long the UE will keep reachable. In this case, SCS/AS may keep transmitting MT NIDD requests to SCEF even if UE goes into PSM. This may trigger SCS/AS unexpected store &forward procedures on SCEF. Because SCEF may buffer undelivered MT Non-IP data, and retransmit the data after UE being reachable again for example in a few hours later. This in turn will consume additional and unnecessary storage, computation and network resource on SCEF. If SCS/AS wants to know the UE reachable information, SCS/AS must perform the event subscription and reporting procedures which would increase a complexity of MT procedure in SCS/AS and resource usage in the network.

For SCEF, when MME/SGSN transmits a UE reachability indication by either a MO NIDD request or a T6a/b connection establishment request to SCEF without the Maximum-UE-Availability-Time, SCEF can know the UE being reachable, but don’t know the reachable duration. In this case, SCEF may transmit all buffered MT Non-IP data to MME/SGSN without prioritization. As SCEF doesn’t know the UE reachable duration, SCEF may keep transmitting buffered MT NIDD requests to MME/SGSN even if the UE being unreachable. The data buffering and retransmission as above may consume unnecessary network, computation and storage resources in the network.

For UE, there is no efficient way to pass the UE reachable duration to SCEF and SCS/AS during the NIDD MO/MT procedure.

To overcome or mitigate at least one of the above-mentioned problems or other problems, the embodiments of the disclosure propose a solution for passing the UE reachability information. An embodiment of the disclosure may pass information of availability time of the UE such as Maximum-UE-Availability-Time via SCEF to SCS/AS with the MT NIDD submit response or the MO NIDD request within NIDD procedures instead of extra event monitoring subscription and reporting procedures. The MME/SGSN can send this information to the SCEF by a T6a/b connection establishment request or a T6a/b NIDD MO request or a NIDD submit response. The SCEF can relay this information to the SCS/AS by a T8 NIDD MT submit response or a T8 NIDD MO request.

In various embodiments, when a UE wants to use the PSM, it may request an active time value and may request a periodic TAU/RAU timer value during every attach and RAU procedures, which are handled as described in TS 23.682 of 3GPP which is incorporated herein by reference in its entirety. If the network such as MME supports PSM and accepts that the UE uses PSM, the MME confirms usage of PSM by allocating an active time value to the UE. The UE starts the active timer when it moves from connected to idle mode and when the active timer expires, the UE moves to the PSM. The active timer determines a duration during which the UE remains reachable for mobile terminated transaction on transition from connected to idle mode.

As described in TS 23.682 of 3GPP, the UE and the network may negotiate over a non-access stratum signaling the use of extended idle mode DRX for reducing the UE’s power consumption. When the UE wants to use the Extended Discontinuous Reception (eDRX) feature, it requests eDRX parameters during the attach and TAU procedures. If the MME accepts the eDRX request, it assigns a Paging Time Window length, and provides this value to the UE during the attach/TAU procedures together with the extended idle mode DRX cycle length. The UE is assumed reachable for paging within the Paging Time Window. After the Paging Time Window length, the MME considers the UE unreachable for paging until the next Paging Hyperfame.

For the UE using one or both of above power saving mechanism (s) , the MME can derive availability time of the UE indicating that the UE is reachable based on the Active Time and/or extended idle mode DRX cycle and/or paging time window, then pass it to SCEF and SCS/AS in NIDD procedures. For example, the availability time may be a timestamp until which the UE is expected to be reachable, such as Maximum-UE-Availability-Time which indicates the timestamp (in Coordinated Universal Time (UTC) ) such as 9: 05 a. m. until which a UE using PSM is expected to be reachable for MT Non-IP data delivery. In another example, the availability time may be represented by time remaining such as 120 second during which the UE is reachable.

Fig. 2 is a flow chart depicting a mobile terminated NIDD procedure according to an embodiment of the present disclosure. For some same or similar parts which have been described with respect to Fig. 1, the description of these parts is omitted here for brevity.

At step 202, if SCS/AS has already activated a NIDD service for a given UE, and has downlink Non-IP data to transmit to the UE, the SCS/AS transmits to the SCEF a MT NIDD Submit Request message including parameters such as External Identifier or MSISDN (Mobile Subscriber International Integrated Services Digital Network number) , SCS/AS Reference ID and Non-IP data.

At step 204, the SCEF checks whether the SCS/AS is authorized to transmit the MT NIDD Submit Request message and that the SCS/AS has not exceeded a quota or rate. If the SCS/AS is authorized to transmit MT NIDD Submit requests and that the SCS/AS has not exceeded the quota (e.g. 200 bytes in 24 hours) or rate (e.g. 10 bytes/hour) of data submission to the SCEF EPS bearer, the flow continues with step 206.

At step 206, if a SCEF EPS bearer context corresponding to the External Identifier or MSISDN included in the MT NIDD Submit Request message is found, then the SCEF transmits toward the MME/SGSN a NIDD Submit Request message including parameters such as User ID, EPS Bearer ID, SCEF ID, Non-IP data, SCEF Wait Time, Maximum Re-transmission time.

At step 208, if the MME/SGSN can immediately deliver the Non-IP data to the UE, e.g. when the UE is already in an ECM_CONNECTED mode, or UE is in an ECM_IDLE mode and MME/SGSN is able to initiate a paging procedure, then the MME/SGSN delivers the Non-IP data to the UE.

At step 210, the MME/SGSN gives a NIDD Submit Response (cause) message towards the SCEF with availability time of the UE indicating that the UE is reachable such as a timestamp until which the UE is reachable and time remaining during which the UE is reachable. For example, the timestamp may be a a parameter “Maximum UE Availability Time” may be added in the NIDD Submit Response (cause) message. The availability time of the UE can be used by the SCEF to determine how to deliver Non-IP data to the UE.

At step 212, the SCEF transmits a MT NIDD Submit Response to the SCS/AS informing of the received results from the MME/SGSN with the availability time of the UE. For example, a parameter “Maximum UE Availability Time” may be added in the MT NIDD Submit Response. The availability time of the UE can be used by the SCS/AS to determine how to deliver Non-IP data to the UE.

Fig. 3 is a flow chart depicting a mobile terminated NIDD procedure with retransmission according to an embodiment of the present disclosure. For some same or similar parts which have been described with respect to Figs. 1-2, the description of these parts is omitted here for brevity.

Steps

302, 304 and 306 are similar to

steps

202, 204 and 206 which have been described with respect to Fig. 2, the description of these steps is omitted here for brevity

At step 308, if the MME/SGSN is aware of the UE being temporarily unreachable or if the MME/SGSN knows that the UE is not scheduled to be reachable within the SCEF Wait Time, while using power saving functions, then the MME/SGSN may transmit a NIDD Submit Response message including parameters such as Cause and Requested Re-Transmission Time towards the SCEF.

At step 310, the SCEF transmits a MT NIDD Submit response message including parameters such as Cause and Requested Re-Transmission Time towards the SCS/AS.

At step 312, when the MME/SGSN detects that the UE is reachable, the MME/SGSN transmits a NIDD Submit Indication message to the SCEF.

At step 314, if the Non-IP data has not been purged, the SCEF transmits toward the MME/SGSN a NIDD Submit Request message including parameters such as User Identity, EPS Bearer ID, SCEF ID, Non-IP data, SCEF Wait Time, Maximum Re-transmission time.

At step 316, the MME/SGSN delivers the Non-IP data to the UE.

At step 318, the MME/SGSN transmits to the SCEF a NIDD Submit Response message including parameters such as availability time of the UE, e.g., a timestamp until which the UE is reachable and time remaining during which the UE is reachable. For example, a parameter “Maximum UE Availability Time” may be added in the NIDD Submit Response message.

At step 320, the SCEF transmits a MT NIDD Submit Response to the SCS/AS informing of the received results from the MME/SGSN. The MT NIDD Submit Response may include parameters such as the availability time of the UE, e.g., the timestamp until which the UE is reachable and time remaining during which the UE is reachable. For example, a parameter “Maximum UE Availability Time” may be added in the NIDD Submit Response message. The availability time of the UE may be used by the SCS/AS to determine how to deliver Non-IP data to the UE.

Fig. 4 is a flow chart depicting a mobile originated NIDD procedure according to an embodiment of the present disclosure. For some same or similar parts which have been described with respect to Figs. 1-3, the description of these parts is omitted here for brevity.

At step 402, when the UE is already in the ECM_CONNECTED mode and has uplink Non-IP data to transmit to the SCS/AS, the UE transmits a non-access stratum (NAS) message with EPS bearer ID and Non-IP data to the MME or the UE transmits data to the SGSN on a packet data protocol (PDP) context of public data network (PDN) type Non-IP associated with a T6b interface.

At step 404, the MME/SGSN transmits a NIDD Submit Request including the availability time of the UE to the SCEF. For example, the NIDD Submit Request may include parameters such as User ID, EBI, SCEF ID, Non-IP data, MO Exception data counter, Maximum UE Availability Time.

At step 406, when the SCEF receives the Non-IP data on a T6a/T6b interface, and finds an SCEF EPS bearer context and the related SCS/AS Reference ID, then it transmits a MO NIDD indication message including the Non-IP data and the availability time of the UE to an appropriate SCS/AS. For example, a new parameter “the availability time of the UE” may be added in the MO NIDD indication message. Then the SCEF may receive a response including a result such as success delivery from the SCS/AS.

At step 408, the SCEF transmits a NIDD Submit Response including a submit result such as success delivery to the SCS/AS.

It is noted that the above embodiments may represent a non-roaming case, and when in a roaming case, an interworking SCEF (IWK-SCEF) may be used to relay the messages between the MME/SGSN and the SCEF. In addition, the embodiments of the present disclosure may employ the architectural reference models as described in section 4.2 of TS 23.682 of 3GPP or any other suitable architectural model in other embodiments.

Fig. 5 is a flow chart depicting a method in a first network element according to an embodiment of the present disclosure. The method 500 may be performed at an apparatus such as the MME/SGSN of Figs 2-4 or any other suitable apparatus. As such, the first network element may provide means for accomplishing various parts of the method 500 as well as means for accomplishing other processes in conjunction with other components. For some same or similar parts which have been described with respect to Figs. 2-4, the description of these parts is omitted here for brevity.

At block 502, the first network element may receive a first message terminated at a UE or originated from the UE. The first message may comprise any suitable data such as Non-IP data and/or IP data. The UE may use a power saving mode or discontinuous reception. For example, when the first message is terminated at the UE, the first network element may receive the first message from any suitable apparatus which wants to transmit the message to the UE, such as SCEF shown in Figs. 2-4. When the first message is originated from the UE, the first network may receive the first message from the UE for example as shown in step 402 of Fig. 4. In an embodiment, the first message may comprise Non-IP data.

The first network element may determine whether the first message can be delivered to the UE when the first message is terminated at the UE. The first network element may use any suitable methods to determine whether the first message can be delivered to the UE. For example, the first network element may be aware of the UE being temporarily unreachable, or the first network element knows that the UE is not scheduled to be reachable within a predefined period, or the UE has notified the first network element of its unreachable state, or the first network element can not page the UE, etc. When the first message can be delivered to the UE, the first network element may deliver the first message to the UE. It is noted that when the first message is originated from the UE, block 504 may be obmitted.

At block 504, the first network element may transmit to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE. The second network element may be the network element such as SCEF as shown in Figs. 2-4. The second message may be any suitable message such as a request or a response. For example, as shown in Figs. 2-3, the second network element such as SCEF may transmit the first message such as a NIDD submit request to the first network element and if the first message has been delivered to the UE for example as shown in step 208 of Fig. 2 and step 316 of Fig. 3, then the first network element may transmit to the second network element such as SCEF a second message such as a NIDD submit response including availability time of the UE for example as shown in step 210 of Fig. 2 and step 318 of Fig. 3. If the first message is originated from the UE for example as shown in step 402 of Fig. 4, then the first network element may transmit to the second network element such as SCEF the second message. The second message may comprise any suitable data such as Non-IP data and/or IP data. In an embodiment, the second message may be a NIDD submit request including availability time of the UE for example as shown in step 404 of Fig. 4.

In an embodiment, the availability time may comprise at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable. For example, the first network element may determine the availability time based on the Active Time and/or extended idle mode DRX cycle and/or paging time window associated with the UE as described above. The availability time may take any suitable form such as a timestamp until which the UE is reachable or time remaining during which the UE is reachable.

In an embodiment, the first message is terminated at the UE and is a NIDD submit request received from the second network element, and the second message is a NIDD submit response message. For example, the first network element such as MME/SGSN may receive the NIDD submit request from the second network element such as SCEF for example as shown in

steps

206 and 314 of Figs. 2-3. The first network element such as MME/SGSN may transmit to the second network element such as SCEF a second message such as a NIDD submit response message with the availability time of the UE for example as shown in

steps

210 and 318 of Figs. 2-3.

In an embodiment, the first message is originated from the UE, and the second message is a NIDD submit request. As shown in Fig. 4, the first network element such as MME/SGSN may receive the first message including Non-IP data from the UE at step 402 and transmit the second message such as NIDD submit request with the availability time of the UE to the second network element such as SCEF at block 404.

In an embodiment, the first network element is the MME/SGSN, and the second network element is the SCEF as shown in Figs. 2-4.

Fig. 6a is a flow chart depicting a method in a second network element according to an embodiment of the present disclosure. The method 600a may be performed at an apparatus such as the SCEF of Figs. 2-4 or any other suitable apparatus. As such, the second network element may provide means for accomplishing various parts of the method 600a as well as means for accomplishing other processes in conjunction with other components. For some same or similar parts which have been described with respect to Figs. 2-5, the description of these parts is omitted here for brevity.

At block 602a, the second network element may receive Non-Internet Protocol data terminated at the UE from a third network element. For example, the third network element may have data to be sent to the UE and then transmit the Non-Internet Protocol data to the second network element. In an embodiment, the Non-Internet Protocol data may be included in a MT NIDD submit request. In an embodiment, as shown in Figs. 2-3, the second network element such as SCEF may receive the Non-Internet Protocol data from the third network element such as SCS/AS.

At block 604a, the second network element such as SCEF may transmit a first message such as a NIDD submit request to the first network element such as MME/SGSN. In this embodiment, the first message may comprise Non-Internet Protocol data and is the NIDD submit request as shown in Figs. 2-3.

At block 606a, the second network element may receive from the first network element a second message including availability time of the UE indicating that the UE is reachable. The UE may use a power saving mode or discontinuous reception. The second message may be any suitable message such as a response. For example, the second network element such as SCEF may transmit the first message such as a NIDD submit request to the first network element, and then receive the second message such as a NIDD submit response including the delivery result and at least the availability time of the UE from the first network element such as MME/SGSN as shown in Figs. 2-3.

At block 608a, the second network element may transmit to a third network element a third message including the availability time of the UE. The third message may be any suitable message such as a response. For example, as shown in Figs. 2-3, the second network element may receive from the third network element such as SCS/AS a MT NIDD submit request and then transmit a third message such as a MT NIDD submit response message including the delivery result and the availability time of the UE to the third network element. In an embodiment, the second network element may perform data delivery terminated at the UE based on the availability time of the UE. For example, the second network element may have buffered or stored data terminated at the UE and then can smartly decide when and how to deliver data terminated at the UE such as the MT Non-IP Data based on the availability time of the UE. Note that the buffered or stored data may be received from the third network element or other suitable devices. The second network element can prioritize the transmission of MT Non-IP Data to the UE using PSM if the UE reachable time window is not long enough to delivery all the data, or stop transmitting MT Non-IP data to UE when the UE is outside of the reachable time window.

Fig. 6b is a flow chart depicting a method in a second network element according to an embodiment of the present disclosure. The method 600b may be performed at an apparatus such as the SCEF of Figs. 2-4 or any other suitable apparatus. As such, the second network element may provide means for accomplishing various parts of the method 600b as well as means for accomplishing other processes in conjunction with other components. For some same or similar parts which have been described with respect to Figs. 2-6a, the description of these parts is omitted here for brevity.

At block 602b, the second network element may receive from the first network element a second message including availability time of the UE indicating that the UE is reachable. The UE may use a power saving mode or discontinuous reception. The second message may be any suitable message such as a request. For example, as shown in Fig. 4, the first network may receive MO Non-IP data from the UE and transmit a second message such as a NIDD submit request including the Non-IP data and the availability time of the UE to the second network element.

At block 604b, the second network element may transmit to a third network element a third message including the availability time of the UE. The third message may be any suitable message such as a request. The third message may comprise any suitable data such as Non-IP data and/or IP data. For example, as shown in Fig. 4, the second network element such as SCEF may receive a NIDD submit request with the availability time of the UE from the MME/SGSN and then transmit the third message such as MO NIDD indication message with the availability time of the UE to the third network element such as SCS/AS. In an embodiment, the second network element may perform data delivery terminated at the UE based on the availability time of the UE. For example, the second network element may have buffered or stored data terminated at the UE and then can smartly decide when and how to deliver data terminated at the UE such as the MT NIDD message based on the availability time of the UE. Note that the buffered or stored data may be received from the third network element or other suitable devices. The second network element can prioritize the transmission of MT Non-IP Data to the UE using PSM if the UE reachable time window is not long enough to delivery all the data, or stop transmitting MT Non-IP data to UE when the UE is outside of the reachable time window.

In an embodiment, the availability time may comprise at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable as described in the previous embodiments.

In an embodiment, the Non-Internet Protocol data is included by the third network element in a Mobile Terminated MT Non-Internet Protocol data delivery, NIDD, submit request, the first message is a NIDD submit request, and/or the second message is a NIDD submit response message and the third message is a MT NIDD submit response message.

Fig. 7a is a flow chart depicting a method in a third network element according to an embodiment of the present disclosure. The method 700a may be performed at an apparatus such as the SCS/AS of Figs 2-4 or any other suitable apparatus. As such, the third network element may provide means for accomplishing various parts of the method 700a as well as means for accomplishing other processes in conjunction with other components. For some same or similar parts which have been described with respect to Figs. 2-5 and 6a-6b, the description of these parts is omitted here for brevity.

At block 702a, the third network element may transmit Non-Internet Protocol data terminated at the UE to the second network element. The Non-Internet Protocol data may be included in a MT NIDD submit request. For example, as shown in Figs. 2-3, if the third network element such as SCS/AC has already activated a NIDD service for the UE and has downlink Non-IP data to transmit to the UE, the SCS/AS transmits a MT NIDD Submit Request message including parameter such as External Identifier or MSISDN, SCS/AS Reference ID, Non-IP data to the SCEF.

At block 704a, the third network element may receive from the second network element a third message including availability time of the UE indicating that the UE is reachable. The UE may use a power saving mode or discontinuous reception. The third message may be any suitable message such as a response. For example, as shown in Figs. 2-3, the third network element such as SCS/AS may transmit Non-Internet Protocol data included in such as a MT NIDD submit request to the second network element such as SCEF, and then receive the third message such as a MT NIDD submit response including at least the availability time of the UE from the second network element.

At block 706a, the third network element may perform data delivery terminated at the UE based on the availability time of the UE. For example, the third network element can smartly decide when and how to deliver data terminated at the UE such as the MT NIDD message based on the availability time of the UE. The third network element can prioritize the transmission of MT Non-IP Data to the UE using PSM if the UE reachable time window is not long enough to delivery all the data, or stop transmitting MT Non-IP data to UE when the UE is outside of the reachable time window.

Fig. 7b is a flow chart depicting a method in a third network element according to an embodiment of the present disclosure. The method 700b may be performed at an apparatus such as the SCS/AS of Figs 2-4 or any other suitable apparatus. As such, the third network element may provide means for accomplishing various parts of the method 700b as well as means for accomplishing other processes in conjunction with other components. For some same or similar parts which have been described with respect to Figs. 2-5, 6a-6b and 7a, the description of these parts is omitted here for brevity.

At block 702b, the third network element may receive from the second network element a third message including availability time of the UE indicating that the UE is reachable. The UE may use a power saving mode or discontinuous reception. The third message may be any suitable message such as a request. As an example, as shown in Fig. 4, the first network may receive a MO Non-IP data from the UE and transmit the second message such as a NIDD submit request including the Non-IP data and the availability time of the UE to the second network element. In this case, the second network element may transmit the third message such as a MO NIDD indication message including the MO Non-IP data and availability time of UE to the third network element such as SCS/AS.

At block 704b (optional) , the third network element may perform data delivery terminated at the UE based on the availability time of the UE. For example, the third network element can smartly decide when and how to deliver data terminated at the UE such as the MT NIDD message based on the availability time of the UE. The third network element can prioritize the transmission of MT Non-IP Data to the UE using PSM if the UE reachable time window is not long enough to delivery all the data, or stop transmitting MT Non-IP data to UE when the UE is outside of the reachable time window.

In an embodiment, the second network element is a SCEF and/or the third network element is a SCS/AS as shown in Figs. 2-4.

Fig. 8 is a block diagram illustrating an apparatus in a first network element capable of implementing the methods as described above. As shown in Fig. 8, the apparatus 800 comprises a processing device 804, a memory 805, and a transceiver 801 in operative communication with the processor 804. The transceiver 801 comprises at least one transmitter 802 and at least one receiver 803. While only one processor is illustrated in Fig. 8, the processing device 804 may comprises a plurality of processors or multi-core processor (s) . Additionally, the processing device 804 may also comprise cache to facilitate processing operations.

Computer-executable instructions can be loaded in the memory 805 and, when executed by the processing device 804, cause the apparatus 800 to implement the above-described methods. In particular, the computer-executable instructions can cause the apparatus 800 to receive a first message terminated at a user equipment, UE, or originated from the UE; and transmit to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

Fig. 9 is a block diagram illustrating an apparatus in a second network element capable of implementing the methods as described above. As shown in Fig. 9, the apparatus 900 comprises a processing device 904, a memory 905, and a transceiver 901 in operative communication with the processor 904. The transceiver 901 comprises at least one transmitter 902 and at least one receiver 903. While only one processor is illustrated in Fig. 9, the processing device 904 may comprises a plurality of processors or multi-core processor (s) . Additionally, the processing device 904 may also comprise cache to facilitate processing operations.

Computer-executable instructions can be loaded in the memory 905 and, when executed by the processing device 904, cause the apparatus 900 to implement the above-described methods. In particular, the computer-executable instructions can cause the apparatus 900 to receive from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable; and transmit to a third network element a third message including the availability time of the UE.

In an embodiment, the computer-executable instructions can cause the apparatus 900 to perform data delivery terminated at the UE based on the availability time of the UE.

In an embodiment, the computer-executable instructions can cause the apparatus 900 to receive Non-Internet Protocol data terminated at the UE from the third network element; and transmitting a first message terminated at the UE comprising the Non-Internet Protocol data to the first network element.

Fig. 10 is a block diagram illustrating an apparatus in a third network element capable of implementing the methods as described above. As shown in Fig. 10, the apparatus 1000 comprises a processing device 1004, a memory 1005, and a transceiver 1001 in operative communication with the processor 1004. The transceiver 1001 comprises at least one transmitter 1002 and at least one receiver 1003. While only one processor is illustrated in Fig. 10, the processing device 1004 may comprises a plurality of processors or multi-core processor (s) . Additionally, the processing device 1004 may also comprise cache to facilitate processing operations.

Computer-executable instructions can be loaded in the memory 1005 and, when executed by the processing device 1004, cause the apparatus 1000 to implement the above-described methods. In particular, the computer-executable instructions can cause the apparatus 1000 to from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.

In an embodiment, the computer-executable instructions can cause the apparatus 1000 to perform data delivery terminated at the UE based on the availability time of the UE.

In an embodiment, the computer-executable instructions can cause the apparatus 1000 to Non-Internet Protocol data terminated at the UE to the second network element, wherein the Non-Internet Protocol data is included in a Mobile Terminated, MT, Non-Internet Protocol Data Delivery, NIDD, submit request and/or the third message is a MT NIDD submit response message.

The embodiments of the disclosure may provide an efficient and timely way to pass the availability time of the UE such as “Maximum-UE-Availability-Time” information to an entity such as IoT application server within a data deliveray procedure such as the NIDD procedure. The cost of UE reachability event monitoring subscription and reporting procedures with existing technology may be saved.

For example, once an IoT application server knows the availability time of the UE, it can smartly decide when and how to deliver the NIDD MT message based on that information, e.g. prioritize the transmission of MT Non-IP Data to the UE using a power saving mechanism if the UE reachable time window is not long enough to delivery all the data. Or the IoT application server may stop transmitting MT Non-IP data to SCEF when a UE is outside of the reachable time window. In this way, the cost of MT Non-IP data buffering and retransmission on the operator network will be saved as well.

In an embodiment, a new information element (IE) “Maximum UE Availability Time” may be added in TDA message in T6 interface between MME/SGSN and SCEF and message “NIDD MT Response” in T8 interface between SCS/AS and SCEF.

In an embodiment, a new IE “Maximum UE Availability Time” may be added in ODR message in T6 interface between MME/SGSN and SCEF and message “NIDD MO Request” in T8 interface between SCS/AS and SCEF.

According to an aspect of the disclosure it is provided a computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program instructions stored therein, the computer-executable instructions being configured to, when being executed, cause an apparatus in a first network element to operate as described above.

According to an aspect of the disclosure it is provided a computer program productcomprising at least one non-transitory computer-readable storage medium having computer-executable program instructions stored therein, the computer-executable instructions being configured to, when being executed, cause an apparatus in a second network element to operate as described above.

According to an aspect of the disclosure it is provided a computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program instructions stored therein, the computer-executable instructions being configured to, when being executed, cause an apparatus a third network element to operate as described above.

According to an aspect of the disclosure it is provided an apparatus in a first network element. The apparatus may comprise means for receiving a first message terminated at a user equipment, UE, or originated from the UE; means for determining whether the first message can be delivered to the UE when the first message is terminated at the UE; and means for transmitting to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.

According to an aspect of the disclosure it is provided an apparatus in a second network element. The apparatus may comprise means for receiving from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable. The method may further comprise means for performing at least one of performing data delivery terminated at the UE based on the availability time of the UE and transmitting to a third network element a third message including the availability time of the UE.

According to an aspect of the disclosure it is provided an apparatus in a third network element. The apparatus may comprise means for receiving from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.

It is noted that any of the components of the apparatus in the first, second and third network element can be implemented as hardware or software modules. In the case of software modules, they can be embodied on a tangible computer-readable recordable storage medium. All of the software modules (or any subset thereof) can be on the same medium, or each can be on a different medium, for example. The software modules can run, for example, on a hardware processor. The method steps can then be carried out using the distinct software modules, as described above, executing on a hardware processor.

The terms “computer program” , “software” and “computer program code” are meant to include any sequences or human or machine cognizable steps which perform a function. Such program may be rendered in virtually any programming language or environment including, for example, C/C++, Fortran, COBOL, PASCAL, assembly language, markup languages (e.g., HTML, SGML, XML) , and the like, as well as object-oriented environments such as the Common Object Request Broker Architecture (CORBA) , JavaTM (including J2ME, Java Beans, etc. ) , Binary Runtime Environment (BREW) , and the like.

The terms “memory” and “storage device” are meant to include, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the memory or storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

In any case, it should be understood that the components illustrated herein may be implemented in various forms of hardware, software, or combinations thereof, for example, application specific integrated circuit (s) (ASICS) , functional circuitry, an appropriately programmed general purpose digital computer with associated memory, and the like. Given the teachings of the disclosure provided herein, one of ordinary skill in the related art will be able to contemplate other implementations of the components of the disclosure.

The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

A method (500) in a first network element, comprising:

Receiving (502) a first message terminated at a user equipment, UE, or originated from the UE; and

transmitting (504) to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.
The method according to claim 1, wherein the availability time comprises at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable.
The method according to claim 1 or 2, wherein the first message comprises Non-Internet Protocol, Non-IP, data.
The method according to any of claims 1-3, wherein the first message is terminated at the UE and is a Non-Internet Protocol Data Delivery, NIDD, submit request received from the second network element, and/or the second message is a NIDD submit response message.
The method according to any of claims 1-3, wherein the first message is originated from the UE, and/or the second message is a Non-Internet Protocol Data Delivery, NIDD, submit request.
The method according to any of claims 1-5, wherein the first network element is a mobility management entity, MME, or a serving general packet radio service, GPRS, support node, SGSN, and/or the second network element is a service capability exposure function, SCEF.
A method (600a, 600b) in a second network element, comprising:

receiving (606a, 602b) from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable; and

transmitting (608a, 604b) to a third network element a third message including the availability time of the UE.
The method according to claim 7, further comprising:

performing data delivery terminated at the UE based on the availability time of the UE.
The method according to claim 7 or 8, wherein the availability time comprises at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable.
The method according any of claims 7-9, further comprising

receiving (602a) Non-Internet Protocol data terminated at the UE from the third network element; and

transmitting (604a) a first message terminated at the UE comprising the Non-Internet Protocol data to the first network element.
The method according claim 10, wherein the Non-Internet Protocol data is included by the third network element in a Mobile Terminated, MT, Non-Internet Protocol data delivery, NIDD, submit request, the first message is a NIDD submit request, and/or the second message is a NIDD submit response message and the third message is a MT NIDD submit response message.
The method according to any of claims 7-9, wherein the second message is a Non-Internet Protocol data delivery, NIDD, submit request comprising Non-Internet Protocol data originated from the UE and/or the third message is a Mobile Originated, MO, NIDD indication message comprising the Non-Internet Protocol data originated from the UE.
The method according to any of claims 7-12, wherein the first network element is a mobility management entity, MME, or a serving general packet radio service, GPRS, support node, SGSN, the second network element is a service capability exposure function, SCEF, and/or the third network element is a service capability server, SCS, or application server, AS.
A method (700a, 700b) in a third network element, comprising:

receiving (704a, 702b) from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.
The method according to claim 14, further comprising:

performing (706a, 704b) data delivery terminated at the UE based on the availability time of the UE.
The method according to claim 14 or 15, wherein the availability time comprises at least one of a timestamp until which the UE is reachable and time remaining during which the UE is reachable.
The method according to any of claims 14-16, further comprising

transmitting (702a) Non-Internet Protocol data terminated at the UE to the second network element,

wherein the Non-Internet Protocol data is included in a Mobile Terminated, MT, Non-Internet Protocol Data Delivery, NIDD, submit request and/or the third message is a MT NIDD submit response message.
The method according to any of claims 14-16, wherein the third message is a Mobile Originated, MO, Non-Internet Protocol Data Delivery, NIDD, indication message comprising Non-Internet Protocol data originated from the UE.
The method according to any of claims 14-18, wherein the second network element is a service capability exposure function, SCEF, and/or the third network element is a service capability server, SCS, or application server, AS.
An apparatus (800) in a first network element, comprising:

a processor (804) ; and

a memory (805) , the memory (805) containing instructions executable by the processor, whereby the apparatus (800) is operative to:

receive a first message terminated at a user equipment, UE, or originated from the UE; and

transmitting to a second network element a second message including availability time of the UE indicating that the UE is reachable when the first message is terminated at the UE and the UE is reachable or the first message is originated from the UE.
The apparatus according to claim 20, wherein the apparatus is operative to perform the method of any one of claims 2 to 6.
An apparatus (900) in a second network element, comprising:

a processor (804) ; and

a memory (805) , the memory (805) containing instructions executable by the processor, whereby the apparatus (800) is operative to:

receive from a first network element a second message including availability time of a user equipment, UE, indicating that the UE is reachable; and

transmit to a third network element a third message including the availability time of the UE.
The apparatus according to claim 22, wherein the apparatus is operative to perform the method of any one of claims 8 to 13.
An apparatus (1000) in a third network element, comprising:

a processor (1004) ; and

a memory (1005) , the memory (1005) containing instructions executable by the processor, whereby the apparatus (1000) is operative to:

receive from a second network element a third message including availability time of a user equipment, UE, indicating that the UE is reachable.
The apparatus according to claim 24, wherein the apparatus is operative to perform the method of any one of claims 15 to 19.
A computer program product comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 1 to 6.
A computer program product comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 7 to 13.
A computer program product comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 14 to 19.
A system comprising:

a first network element comprising an apparatus according to claim 20 or 21;

a second network element comprising an apparatus according to claim 22 or 23; and

a third network element comprising an apparatus according to claim 24 or 25.