WO2014048478A1

WO2014048478A1 - Paging

Info

Publication number: WO2014048478A1
Application number: PCT/EP2012/069121
Authority: WO
Inventors: Sudhish KANICHU VEEDU
Original assignee: Nokia Siemens Networks Oy
Priority date: 2012-09-27
Filing date: 2012-09-27
Publication date: 2014-04-03

Abstract

The invention relates to an apparatus (300) comprising: at least one processor (304) and at least one memory (302) including a computer program code, the at least one memory (302) and the computer program code configured to, with the at least one processor (304), cause the apparatus (300) at least to: obtain a request for paging a user device (202); prepare a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device (204), and convey the paging message to the paging area (206).

Description

DESCRIPTION

Title Paging

Field

The invention relates to apparatuses, methods, systems, computer programs, computer program products and computer-readable media. Background

The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.

In the long term evolution (LTE), a mobility management entity (MME) is a control element in the evolved packet core (EPC). Typically, the MME has a logically direct control plane (CP) connection to a user device which is used as the primary control channel between the user device and the network. Some of MME's responsibilities or functionalities are authentication and security, mobility management and managing subscription profile and service connectivity.

Brief description

According to an aspect of the present invention, there is provided an apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: obtain a request for paging a user device; prepare a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and convey the paging message to the paging area. According to yet another aspect of the present invention, there is provided a method comprising: obtaining a request for paging a user device; preparing a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on infor- mation provided by a serving node of the user device, and conveying the paging message to the paging area.

According to yet another aspect of the present invention, there is provided an apparatus comprising: means for obtaining a request for paging a user device; means for preparing a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and means for conveying the paging message to the paging area.

According to yet another aspect of the present invention, there is provided a computer program embodied on a computer-readable storage medium, the computer program com- prising program code for controlling a process to execute a process, the process comprising: obtaining a request for paging a user device; preparing a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and conveying the paging message to the paging area.

List of drawings

Some embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which

Figure 1 illustrates an example of a system;

Figure 2 is a flow chart, and

Figure 3 illustrates examples of apparatuses.

Description of some embodiments

The following embodiments are only examples. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may also contain also features, structures, units, modules etc. that have not been specifically mentioned.

Embodiments are applicable to any user device, such as a user terminal, as well as to any network element, relay node, server, node, corresponding component, and/or to any communication system or any combination of different communication systems that support required functionalities. The communication system may be a wireless communication system or a communication system utilizing both fixed networks and wireless networks. The protocols used, the specifications of communication systems, appara- tuses, such as servers and user terminals, especially in wireless communication, develop rapidly. Such development may require extra changes to an embodiment. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, embodiments.

In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE- A), that is based on orthogonal frequency multiplexed access (OFDMA) in a downlink and a single-carrier frequency-division multiple access (SC-FDMA) in an uplink, without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS).

In an orthogonal frequency division multiplexing (OFDM) system, the available spectrum is divided into multiple orthogonal sub-carriers. In OFDM systems, the available bandwidth is divided into narrower sub-carriers and data is transmitted in parallel streams. Each OFDM symbol is a linear combination of signals on each of the subcarriers. Further, each OFDM symbol is preceded by a cyclic prefix (CP), which is used to decrease Inter- Symbol Interference. Unlike in OFDM, SC-FDMA subcarriers are not independently modu- lated. Typically, a (e)NodeB ("e" stands for evolved) needs to know channel quality of each user device and/or the preferred precoding matrices (and/or other multiple input- multiple output (MIMO) specific feedback information, such as channel quantization) over the allocated sub-bands to schedule transmissions to user devices. Such required infor- mation is usually signalled to the (e)NodeB.

Figure 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in Figure 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in Figure 1 .

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties. Figure 1 shows a part of a radio access network based on E-UTRA, LTE, LTE-

Advanced (LTE-A) or LTE/EPC (EPC = evolved packet core, EPC is enhancement of packet switched technology to cope with faster data rates and growth of Internet protocol traffic). E-UTRA is an air interface of LTE Release 8 (UTRA= UMTS terrestrial radio access, UMTS= universal mobile telecommunications system). Some advantages obtainable by LTE (or E-UTRA) are a possibility to use plug and play devices, and Frequency Division Duplex (FDD) and Time Division Duplex (TDD) in the same platform.

Figure 1 shows user devices 100 and 102 configured to be in a wireless connection on one or more communication channels 104 and 106 in a cell with a (e)NodeB 108 providing the cell. The physical link from a user device to a (e)NodeB is called uplink or reverse link and the physical link from the (e)NodeB to the user device is called downlink or forward link.

The NodeB, or advanced evolved node B (eNodeB, eNB) in LTE-Advanced, is a computing device configured to control the radio resources of communication system it is coupled to. The (e)NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment.

The (e)NodeB includes transceivers, for example. From the transceivers of the (e)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e)NodeB is further connected to core network 1 10 (CN). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc.

A communications system typically comprises more than one (e)NodeB in which case the (e)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signalling purposes.

The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 1 12. The communication network may also be able to support the usage of cloud services. It should be appreciated that

(e)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

The user device (also called UE, user equipment, user terminal, terminal de- vice, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station.

The user device typically refers to a portable computing device that includes wireless mo- bile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. The user device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses.

It should be understood that, in Figure 1 , user devices are depicted to include 2 antennas only for the sake of clarity. The number of reception and/or transmission antennas may naturally vary according to a current implementation.

Further, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in Figure 1 ) may be implemented. It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practise, the system may comprise a plurality of (e)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the NodeBs or eNodeBs may be a Home(e)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometres, or smaller cells such as micro-, femto- or picocells. The

(e)NodeBs of Figure 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one node B provides one kind of a cell or cells, and thus a plurality of (e) Node Bs are required to provide such a network structure.

Recently for fulfilling the need for improving the deployment and performance of commu- nication systems, the concept of "plug-and-play" (e)NodeBs has been introduced. Typically, a network which is able to use "plug-and-play" (e)Node Bs, includes, in addition to Home (e)NodeBs (H(e)nodeBs), a home node B gateway, or HNB-GW (not shown in Figure 1 ). A HNB Gateway (HNB-GW), which is typically installed within an operator's network may aggregate traffic from a large number of HNBs back to a core network. One embodiment may be carried out by a device configured to operate as a mobility management entity (MME). The MME is a control element in the evolved packet core (EPC). In practice, the MME may be a server located in operator's premises. Typically, the MME has a logically direct control plane (CP) connection to a user device which is used as the primary control channel between the user device and the network. Some of MME's re- sponsibilities or functionalities may be authentication and security, mobility management, managing subscription profile and service connectivity. The MME may also be provided as a cloud service.

In the mobility management, in general, an MME may keep track on the location of user devices in its service area. The MME may request resources from an (e)NodeB as well as from a serving gateway it selects for a user device. The MME may track the user device's location either on the (e)NodeB level, when the user device is in an active state, or at the level of tracking area (TA) which is a group of (e)NodeBs, when the user device is in an idle mode. If data to be forwarded to a user device is received in the idle mode, the MME will usually be notified and it may request (e)NodeBs in a user device's tracking area to page the user device. A paging message typically comprises the identity of the user device being paged. Thus, usually, the user device whose identity matches with the identity transmitted in the paging message responds, whereas other user devices do not. The MME may learn the initial tracking area of the user device through an initial attach proce- dure. After the attach procedure, when the user device moves to a different tracking area, it may use the tracking area update procedure to inform the MME of its new tracking area.

In paging, typically, an MME searches for the last known tracking area of the user device to be paged and sends a paging message to each (e)NodeB belonging to the tracking area. Each (e)NodeB in turn sends the paging message over each of the cells that belong to the tracking area. This usually results in heavy paging traffic over the radio interface.

An embodiment is suitable for paging a user device in idle mode by an MME.

The embodiment starts in block 200 of Figure 2.

In block 202, a request for paging a user device is obtained.

A request for paging may be obtained by receiving a paging triggering message from a serving gateway (SGW) or from any other entity that controls user device paging. In addition to the request, information on identifying the user device to be paged, such as a user device identity, may also be obtained. The paging at issue is typically idle mode paging.

In block 204, a paging message is prepared for a paging area. The paging area comprises a limited number of nodes compared to a tracking area of the user device. The selection of the nodes is based on information provided by a serving node and possibly also on information on or provided by one or more neighbour nodes of the user device. Some exemplifying embodiments are disclosed in further detail below.

A paging area may be determined as an optimized or limited (e)NodeB identity (ID) list that includes only those (e)NodeBs under which the user device to be paged locates with high probability. The paging area does not comprise the whole tracking area. The paging area may be determined in advance to be used in one or more future paging procedures.

It should be appreciated that if paging throughout the paging area does not result in a successful page attempt, the paging may be carried out over the entire tracking area.

As simplified, the paging area may be determined at two phases: collecting mobility data of the user device to be paged and processing the mobility data to obtain statistical information. The mobility data may be collected from measurement reports obtained from the user device as defined in the 3GPP specification. These measurement reports may be conveyed by radio resource control messages and comprise usually both serving cell measurements as well as neighbouring cell measurements. The user device typically carries out these measurements when in connected state. Typically, a user device sends its measurement report to an (e)NodeB which then transforms the data into a "connected state mobility record per UE (Mobility Record)" -form for an MME. The mobility data may be stored user device-wise. The mobility data is typically collected as a (regularly) repetitive procedure and it may be used also for other purposes than for idle mode paging. In one embodiment, an MME actively requests for mobility information or data using

"ConnStateMobilityRecordReq" -message and the corresponding (e)NodeB responds using "ConnStateMobilityRecordResp" -message. In another embodiment, an (e)NodeB notifies the MME of such information using "ConnStateMobilityRecordlnfo" message. Both messages typically also comprise information on user device's identity. The MME or (e)NodeB may trigger this message exchange upon detecting a state transition from connected state to idle state of the associated bearer, handover, or any other event wherein the identity of the serving (and neighbour (e)NodeB) is informed.

The mobility data may be processed to obtain statistical information in which case an MME may timestamp information on serving node identity, when such information is avail- able. Events when the serving node identity may be obtained comprise state transitions from connected state to idle state and vice versa, handovers, etc. Based on the timestamp, a particular time period may be chosen and the detected serving (e)NodeB identity may be added to a list stored at that time period. Typically, each serving node appears on the list only once that is the node may be added on the list when it is identified for the first time.

Additionally, the connect-disconnect history record of a user device may be gathered and stored. This may be called accumulation of history information or record. The history record comprises information on state transitions from connected state to idle state and vice versa or handovers, etc. for a predetermined period of time, such as a day, week or month. By this accumulation, a mobility pattern may be determined. The mobility pattern gives information on the behavior of the user device in the past and it may be used to predict one or more probable serving nodes. This is possible, if the mobility of the user device has some conformity or it follows a rule that is to say it forms a detectable pattern. On the other hand, if the mobility of the user device cannot be predicted reliably enough, it may be an indication to carry out the paging in a larger area, such as over a tracking area. The accumulation of history information and/or determination of the mobility pattern may be carried out as a (regularly) repetitive procedure or even continuously. The mobility pattern may also be determined when needed. In one embodiment, the history record or information of serving nodes may be gathered over a predetermined period of time, such as a day, week or month. For example, a day may be divided into three time periods, such as 00 hours to 09 hours is one period, 09 hours to 18 hours is another period and 18 hours to 00 hours is yet another period. The accumulation of the history record may be carried out by storing the history record of one or more connected user devices in one day at a respective time period and for a couple of weeks or a month in order to determine a mobility pattern.

It should be appreciated that the determination of the mobility pattern disclosed herein is only an example and all methods suitable for prediction of probable serving nodes are applicable. A paging area may be determined as follows: when a paging request is obtained it is timestamped and timestamped mobility information of a user device at issue is retrieved. The mobility information may comprise information on last serving node and also on one or more neighbor nodes. These two time stamps are compared and if the difference is small, such as a few seconds, it can be presumed that the mobility record is recent and at least relatively reliable, and thus the user device locates quite probably in the area of the serving node or in that of one of the neighbour nodes. Therefore, the paging area may comprise this last serving node and at least one of the neighbour nodes. However, if the difference between timestamps is bigger, (accumulated) history information or record may be used to determine the paging area in the manner explained above. In one embodiment, a threshold for the difference may be set to be used in the comparison in which case, if the difference is below a predetermined threshold, the paging area comprises the last serving node and at least one neighbour node, and if the difference exceeds the predetermined threshold, nodes for the paging area are chosen by using history information or record. Additionally, the number of (e)NodeB's may be compared to the number of (e)NodeB's in the original tracking area to determine an upper limit to the nodes for making the paging area to include fewer nodes than the tracking area.

In block 206, the paging message is conveyed to the paging area. This may be carried out by using a "normal" paging message used for idle mode paging which is sent to selected (e)NodeBs. In this case the selection is implemented by a paging area. As stated above, the paging area may be determined as an optimized or limited (e)NodeB identity (ID) list that includes only those (e)NodeBs under which the user device to be paged is located with high probability.

It should be appreciated that if paging throughout the paging area does not result in a successful page attempt, the paging may be carried out over the entire tracking area. In other words, the paging for the user device in question may be repeated but for a larger area. The embodiment ends in block 208. The embodiment is repeatable in many ways. One example is shown by arrow 210 in Figure 2.

The steps/points, signaling messages and related functions described above in Figure 2 are in no absolute chronological order, and some of the steps/points may be performed simultaneously or in an order differing from the given one. Other functions may also be executed between the steps/points or within the steps/points and other signaling messages sent between the illustrated messages. Some of the steps/points or part of the steps/points can also be left out or replaced by a corresponding step/point or part of the step/point.

It should be understood that conveying, broadcasting, signalling transmitting and/or re- ceiving may herein mean preparing a data conveyance, broadcast, transmission and/or reception, preparing a message to be conveyed, broadcasted, signalled, transmitted and/or received, or physical transmission and/or reception itself, etc. on a case by case basis. The same principle may be applied to terms transmission and reception as well.

An embodiment provides an apparatus which may be a mobility management entity or another suitable apparatus capable to carry out processes described above in relation to

Figure 2.

It should be appreciated that an apparatus may include or otherwise be in communication with a control unit, one or more processors or other entities capable of carrying out operations according to the embodiments described by means of Figure 2. It should be under- stood that each block of the flowchart of Figure 2 and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry. Figure 3 illustrates a simplified block diagram of an apparatus according to an embodiment.

As an example of an apparatus according to an embodiment, it is shown apparatus 300, such as a node, including facilities in control unit 304 (including one or more processors, for example) to carry out functions of embodiments according to Figure 3. The facilities may be software, hardware or combinations thereof as described in further detail below.

In Figure 3, block 306 includes parts/units/modules needed for reception and transmission, usually called a radio front end, RF-parts, radio parts, radio head, etc.

Another example of apparatus 300 may include at least one processor 304 and at least one memory 302 including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: obtain a request for paging a user device, prepare a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and convey the paging message to the paging area.

Yet another example of an apparatus comprises means 304 (306) for obtaining a request for paging a user device, means 304 for preparing a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and means 304 (306) for conveying the paging message to the paging area.

Yet another example of an apparatus comprises an obtaining unit configured to obtain a request for paging a user device, preparer configured to prepare a paging mes- sage for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and conveying unit configured to convey the paging message to the paging area.

It should be understood that the apparatuses may include or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. This is depicted in Figure 3 as optional block 306. Although the apparatuses have been depicted as one entity in Figure 3, different modules and memory may be implemented in one or more physical or logical entities.

An apparatus may in general include at least one processor, controller or a unit designed for carrying out control functions operably coupled to at least one memory unit and to vari- ous interfaces. Further, the memory units may include volatile and/or non-volatile memory. The memory unit may store computer program code and/or operating systems, information, data, content or the like for the processor to perform operations according to embodiments. Each of the memory units may be a random access memory, hard drive, etc. The memory units may be at least partly removable and/or detachably operationally cou- pled to the apparatus. The memory may be of any type suitable for the current technical environment and it may be implemented using any suitable data storage technology, such as semiconductor-based technology, flash memory, magnetic and/or optical memory devices. The memory may be fixed or removable.

The apparatus may be, include or be associated with at least one software application, module, unit or entity configured as arithmetic operation, or as a program (including an added or updated software routine), executed by at least one operation processor. Programs, also called program products or computer programs, including software routines, applets and macros, may be stored in any apparatus-readable data storage medium and they include program instructions to perform particular tasks. Computer pro- grams may be coded by a programming language, which may be a high-level programming language, such as objective-C, C, C++, C#, Java, etc., or a low-level programming language, such as a machine language, or an assembler.

Modifications and configurations required for implementing functionality of an embodiment may be performed as routines, which may be implemented as added or up- dated software routines, application circuits (ASIC) and/or programmable circuits. Further, software routines may be downloaded into an apparatus. The apparatus, such as a node device, or a corresponding component, may be configured as a computer or a microprocessor, such as single-chip computer element, or as a chipset, including at least a memory for providing storage capacity used for arithmetic operation and an operation pro- cessor for executing the arithmetic operation.

Embodiments provide computer programs embodied on a distribution medium, comprising program instructions which, when loaded into electronic apparatuses, constitute the apparatuses as explained above. The distribution medium may be a non-transitory medium. Other embodiments provide computer programs embodied on a computer readable storage medium, configured to control a processor to perform embodiments of the methods described above. The computer readable storage medium may be a non-transitory medium. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distri- bution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers. The computer readable medium or computer readable storage medium may be a non-transitory medium.

The techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, digitally enhanced circuits, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation may be carried out through modules of at least one chip set (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case it may be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of systems described herein may be rearranged and/or complimented by additional components in order to facilitate achieving the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An apparatus comprising:

at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

obtain a request for paging a user device;

prepare a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selec- tion of the nodes is based on information provided by a serving node of the user device, and

convey the paging message to the paging area.

2. The apparatus of claim 1 , wherein the request for the paging comprises user device identification.

3. The apparatus of any claim 1 or 2, wherein the obtained request for paging is timestamped.

4. The apparatus of any preceding claim, further comprising causing the apparatus to:

obtain information on a last serving node of the user device and at least one neighbour node, and

timestamp the obtained information for the selection of the nodes for the paging area.

5. The apparatus of any preceding claim, further comprising causing the apparatus to:

gather statistical information on serving nodes by time-stamping and storing ob- tained information on serving nodes during a predetermined time period for the selection of the nodes for the paging area.

6. The apparatus of claim 4 or 5, further comprising causing the apparatus to: determine difference between the timestamped paging request and the timestamped information on the last serving node and at least one neighbour node, if the difference is below a predetermined threshold, the paging area comprises the last serving node and at least one neighbour node, and if the difference exceeds the predetermined threshold, nodes for the paging area are chosen by using the gathered statistical information.

7. The apparatus of any preceding claim, further comprising causing the apparatus to:

request information on a serving node of the user device by using

"ConnStateMobilityRecordReq" -message and receive the information in a

"ConnStateMobilityRecordResp" -message, or receive the information in

"ConnStateMobilityRecordlnfo" -message.

8. The apparatus of any preceding claim, further comprising causing the apparatus to:

obtain information on the failure of paging on the paging area, and

carry out paging on the tracking area of the user device.

9. The apparatus of any preceding claim, the apparatus comprising a mobile management entity.

10. A computer program comprising program instructions which, when loaded into the apparatus, carry out the processes of any preceding claim 1 to 8.

1 1 . A method comprising:

obtaining a request for paging a user device;

preparing a paging message for a paging area, which paging area comprises a limited number of nodes compared to a tracking area of the user device and wherein the selection of the nodes is based on information provided by a serving node of the user device, and

conveying the paging message to the paging area.

12. The method of claim 1 1 , wherein the request for the paging comprises user device identification.

13. The method of claim 1 1 or 12, wherein wherein the obtained request for paging timestamped.

14. The method of any preceding claim 1 1 to 13, further comprising:

obtaining information on a last serving node of the user device and at least one neighbour node, and

timestamping the obtained information for the selection of the nodes for the paging area.

15. The method of any preceding claim 1 1 to 14, further comprising:

gathering statistical information on serving nodes by time-stamping and storing obtained information on serving nodes during a predetermined time period for the selection of the nodes for the paging area.

16. The method of claim 14 or 15, further comprising:

determining difference between the timestamped paging request and the timestamped information on the last serving node and at least one neighbour node, if the difference is below a predetermined threshold, the paging area comprises the last serving node and at least one neighbour node, and if the difference exceeds the predetermined threshold, nodes for the paging area are chosen by using the gathered statistical information.

17. The method of any preceding claim 1 1 to 16, further comprising:

requesting information on a serving node of the user device by using

"ConnStateMobilityRecordReq" -message and receiving the information in a

"ConnStateMobilityRecordResp" -message, or receiving the information in

"ConnStateMobilityRecordlnfo" -message.

18. The method of any preceding claim 1 1 to 17, further comprising:

obtaining information on the failure of paging on the paging area, and carrying out paging on the tracking area of the user device.

19. An apparatus comprising means for carrying out the method according to any one of claims 1 1 to 18.

20. A computer program embodied on a computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising:

obtaining a request for paging a user device;

conveying the paging message to the paging area.