WO2016162049A1

WO2016162049A1 - Controlling monitoring of radio bearers of a wireless device

Info

Publication number: WO2016162049A1
Application number: PCT/EP2015/057496
Authority: WO
Inventors: Peter Hedman; Hans RÖNNEKE
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2015-04-07
Filing date: 2015-04-07
Publication date: 2016-10-13

Abstract

There is provided mechanisms for controlling monitoring radio bearers of a wireless device. A method is performed by a wireless device in connected mode. The method comprises acquiring timing information indicating network reachability of the wireless device. The method comprises controlling monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

Description

CONTROLLING MONITORING OF RADIO BEARERS

OF A WIRELESS DEVICE

TECHNICAL FIELD

Embodiments presented herein relate to controlling monitoring radio bearers of a wireless device, and particularly to a method, a wireless device, a computer program, and a computer program product for controlling monitoring radio bearers of a wireless device. Embodiments presented herein further relate to scheduling radio bearers to a wireless device, and

particularly to a method, a core network node, a computer program, and a computer program product for scheduling radio bearers to a wireless device.

BACKGROUND

In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its

parameters and the physical environment in which the communications network is deployed.

For example, one parameter in providing good performance and capacity for a given communications protocol in a communications network is the ability to allow devices to be in a power saving mode. Devices applying power saving techniques will be unavailable for receiving information during periods when the device is "sleeping" (i.e. where parts of the device are switched off to save power). One challenge is to allow devices to sleep while efficiently enable the possibility to reach such devices when they are available.

The 3rd Generation Partnership Project (3GPP) technical report TR 23.709 vi.1.1 presents an enhanced Power Saving Mode (ePSM) for wireless devices. Based on network configuration when there is no data communication the wireless device can alternate between successive Idle mode interval and PSM interval that are repeated periodically. The period of the repetitive Idle-cum- PSM cycle (further referred to as "ePSM cycle") is equal to the sum of a configured Idle mode sojourn time (Ti) plus a PSM sojourn time (Tp). The repetitive (Ti + Tp) pattern can be made deterministic by locking it on an absolute clock reference (Tref). In other words, the combined (Ti + Tp) cycle starts at instants defined as t = Tref + N * (Ti + Tp), where N is a whole number (i.e., an integer).

If the wireless device needs to break the cycle for any reason (e.g. initiating management object (MO) communication, responding to paging, sending a Periodic tracking area update (TAU), etc.), it returns to the (Ti + Tp) cycle as soon as the network releases the radio resource control (RRC) connection. If the (Ti + Tp) cycle is locked to an absolute clock reference then this may involve an exceptional truncation or extension of the very first Ti or Tp interval, allowing the wireless device to lock on the absolute reference clock.

The parameters defining the periodic cycle (Tref, Ti, Tp) may be provided to a 3rd party application server (AS) either by pre-configuration or by using a Service Capability Enablement Function (SCEF).

Illustrated in Figure l is a call flow for configuration of ePSM in the wireless device.

301. The wireless device (WD) sends a TAU Request message, either due to mobility or due to Periodic TAU timer expiry. If the wireless device wishes to use ePSM, it includes a set of parameters that describe the desired ePSM cycle e.g. the duration of Idle sojourn time (Ti), the duration of PSM sojourn time (Tp) and possibly an absolute clock reference (Tref). According to TR 23.709 vi.1.1, the absolute clock reference should be based on a clock that can be made available both within the wireless device and the AS. For example, Universal Time or global positioning system (GPS) time may be used.

302. The mobility management entity (MME) decides if it allows ePSM based on operator's configuration. If the MME decides to accept the request, it forwards the description of the ePSM cycle to a Service Capability Exposure Function (SCEF) along with an identity (UE ID) of the wireless device. The MME may modify the values describing the ePSM cycle if the MME does not accept the values as proposed by the wireless device. Alternatively, Tp and Ti timer values may be configured in the home subscriber server (HSS) as part of wireless device subscription data and downloaded to the MME. If the MME receives this information from the HSS it may use it to override the values requested by the wireless device.

303. The MME sends a TAU Accept message including the approved description of the ePSM cycle (i.e. the original parameter values as proposed by the wireless device in step 301, or modified values).

304. At some point the evolved Node B (eNB) releases the RRC connection. At this point the wireless device enters the ePSM cycle by typically going through Idle mode first. The RRC connection release message is

asynchronous (i.e. it can occur at any instant), whereas, according to TR 23.709 vi.1.1, the ePSM cycle is locked to an absolute time reference. This means that step 304 may occur either within the "Idle interval" or within the "PSM interval" of the ePSM cycle.

305. A third party AS wishing to send mobile terminating (MT) data to this wireless device registers with the SCEF and obtains the description of the wireless device's ePSM cycle. Given that the ePSM cycle is described relative to an absolute time reference (Tref), the AS needs to fetch the ePSM description from the SCEF only once. The AS may also subscribe to be notified in case the ePSM cycle parameters are modified or if ePSM is cancelled for this wireless device.

306. The Periodic TAU timer is independent of the ePSM cycle. Upon this timer's expiry, the wireless device sends a periodic TAU Request message. The wireless device can use this opportunity to request a change of ePSM parameters or cancel the ePSM. In such a case the MME contacts the SCEF (not shown in Figure 1) to update it with the new ePSM description or indication that the wireless device is not using ePSM anymore. The SCEF can then notify all ASs (not shown in Figure 1) interested in this wireless device about the change. Conversely, if the wireless device is happy with the current ePSM configuration, it may indicate this to the MME by sending the same values. The wireless device may cancel ePSM by not including any ePSM- related parameters.

Figure 2 describes the call flow for MT communication towards a wireless device in ePSM. 401. At the beginning of the call flow the wireless device has entered the ePSM cycle and is alternating between the "Idle interval" and the "PSM interval". The 3rd party AS obtains the ePSM cycle description for this wireless device.

402. When the AS has MT data for sending, it waits until the wireless device enters the "Idle interval" before sending the MT packet(s).

403. The MT packets are short term buffered in the serving gateway (SGW). The SGW sends a Downlink Data Notification (DDN) message to the MME to initiate paging.

404. The MME triggers paging. 405. Given that wireless device is currently inside the "Idle interval" it is able to read the paging message. The wireless device establishes a connection with the network and enters Connected mode. While in Connected mode, the ePSM cycle runs in parallel, but is not used in any way. The wireless device just needs to keep track of the ePSM cycle in the background so that it can later lock on it again.

406. After the data communication is terminated, at some point the network decides to release the RRC connection. In Figure 2 it is assumed that the RRC connection is released within the "Idle interval". The wireless device may lock immediately on the ePSM cycle, as a result of which the very first "Idle interval" will be truncated.

The ePSM procedure as outlined above supports power saving for wireless devices in Idle mode. However, it could be advantageous to enable power saving and efficient signaling for wireless devices which initiate and/or receive communication more frequent than e.g. tens of minutes.

If ePSM is extended to connected mode by maintaining scheduling according to ePSM then additional delays are caused as soon as the "Active period" is left and the wireless device enters the power saving state. One way to adapt the above disclosed ePSM procedure to Connected mode could be to let one or more nodes in the radio access network (RAN) buffer the downlink (DL) packets when the wireless device is not active. This may cause further issues with forwarding of the packets in case the wireless device wakes up in another cell than the cell served by any of the RANs buffering the packets.

Further, the AS would need an additional signaling interface with the SCEF, i.e. the operator network, to retrieve the parameters Ti, Tp and Tref. The SCEF would also be required to be stateful and store the required parameters.

Hence, there is still a need for a improved monitoring of radio bearers of a wireless device.

SUMMARY

An object of embodiments herein is to provide efficient monitoring of radio bearers of a wireless device.

According to a first aspect there is presented a method for controlling monitoring radio bearers of a wireless device. The method is performed by a wireless device in connected mode. The method comprises acquiring timing information indicating network reachability of the wireless device. The method comprises controlling monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

Advantageously this provides efficient monitoring of radio bearers of a wireless device. Advantageously this enables the wireless device to be kept in connected mode and still save power in more efficient manner than if DRX is extended with longer values.

Advantageously, this enables the wireless device to be kept in connected mode longer. By keeping the wireless device longer in connected mode signaling can be reduced.

Advantageously, this efficiently supports mobility as it allows packet addressed to the wireless device to be scheduled from the core network rather than buffered in radio access network. According to a second aspect there is presented a wireless device for controlling monitoring radio bearers of the wireless device in connected mode. The wireless device comprises a processing unit. The processing unit is configured to cause the wireless to acquire timing information indicating network reachability of the wireless device. The processing unit is configured to cause the wireless to control monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

According to a third aspect there is presented a computer program for controlling monitoring radio bearers of the wireless device in connected mode, the computer program comprising computer program code which, when run on a processing unit of a wireless device, causes the wireless device to perform a method according to the first aspect.

According to a fourth aspect there is presented a method for scheduling radio bearers to a wireless device. The method is performed by a core network node having a radio access network interface. The method comprises acquiring timing information indicating network reachability of a wireless device in connected mode. The method comprises controlling scheduling of radio bearers to the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device. According to a fifth aspect there is presented a core network node for scheduling radio bearers to a wireless device. The core network node has a radio access network interface and comprises a processing unit. The processing unit is configured to cause the core network node to acquire timing information indicating network reachability of a wireless device in connected mode. The processing unit is configured to cause the core network node to control scheduling of radio bearers to the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device. According to a sixth aspect there is presented a computer program for scheduling radio bearers to a wireless device, the computer program comprising computer program code which, when run on a processing unit of a core network node having a radio access network interface, causes the core network node to perform a method according to the fourth aspect. According to a seventh aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect and the sixth aspect and a computer readable means on which the computer program is stored.

It is to be noted that any feature of the first, second, third, fourth, fifth, sixth and seventh aspects may be applied to any other aspect, wherever

appropriate. Likewise, any advantage of the first aspect may equally apply to the second, third, fourth, fifth, sixth, and/or seventh aspect, respectively, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

Figs, l and 2 are signalling call flows according to prior art;

Fig. 3 is a schematic diagram illustrating a communication network according to embodiments;

Fig. 4a is a schematic diagram showing functional units of a wireless device according to an embodiment;

Fig. 4b is a schematic diagram showing functional modules of a wireless device according to an embodiment;

Fig. 5a is a schematic diagram showing functional units of a core network node according to an embodiment; Fig. 5b is a schematic diagram showing functional modules of a core network node according to an embodiment;

Fig. 6 shows one example of a computer program product comprising computer readable means according to an embodiment;

Figs. 7, 8, 9, and 10 are flowcharts of methods according to embodiments; Fig. 11 and 12 are signalling call flows according to embodiments;

Fig. 13 schematically illustrates states of a wireless device; and

Fig. 14 schematically illustrates a decision tree for a core network node.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

Fig. 3 is a schematic diagram illustrating a communications network 10 where embodiments presented herein can be applied. The communications network 10 comprises a radio access network (RAN) n, a core network (CN) 14, and a service network 17. In turn the RAN 11 comprises a network node (NN) 12 embodied as a radio access network node (such as a radio base station, a base transceiver station; a node B, or an evolved node B). The RAN 11 may further comprise an optional radio network controller (RNC) 13 or similar logic unit. As the skilled person understands, the RAN 11 may comprise a plurality of NNs 12 and a plurality of optional RNCs 13. The herein disclosed embodiments are not limited to a particular number of NNs 11 (or RNCs 13).

The RAN 11 provides network connectivity to a wireless device (WD) 19 served by the NN 11. The wireless device 19 may be embodied as a portable wireless device, a mobile station, a mobile phone, a handset, a wireless local loop phone, a user equipment (UE), a smartphone, a laptop computer, a tablet computer, a radio modem, an Internet-of-things device, a sensor, etc. As the skilled person understands, a plurality of wireless devices 19 may be operatively connected to the RAN 11. The herein disclosed embodiments are not limited to a particular number of wireless devices 19.

In order for the wireless device 19 to access service as provided by the service network 17, for example to receive packets from, and transmit packets to, an application server (AS) 19, the traffic from the wireless device 19 is passed through the RAN 11 and the CN 14. The CN 14 thus provides routing of traffic to and from the wireless device 19. However, as the skilled person understands, also further functions, such as aggregation, security, service invocation, charging, control, switching, etc. are provides by the CN 14.

Relevant for the embodiments disclosed herein the CN particularly comprises a core network node 15 which may be a mobility management entity (MME), a serving general packet radio service support node (SGSN), or a serving gateway (SGW). The core network node has a RAN interface (i.e., an interface to the RAN 11). Particularly relevant for the embodiments disclosed herein the core network node 15 is involved in the bearer activation/deactivation process for the wireless device 19. When embodied as a SGW, the core network node may route and forward user data packets, while also acting as the mobility anchor for the user plane during inter-eNodeB handovers and as the anchor for mobility between LTE and other 3GPP technologies. The SGW may thus further act as a core network mobility anchor node. The packet data network gateway (PGW) 16 provides connectivity from the wireless device to external packet data networks, such as the service network 17 by being the point of exit and entry of traffic for the wireless device 19. The wireless device 19 may have simultaneous connectivity with more than one PGW for accessing multiple packet data networks.

The embodiments disclosed herein relate to controlling monitoring radio bearers of the wireless device. In order to obtain such controlling there is provided a wireless device, a method performed by the wireless device, a computer program comprising code, for example in the form of a computer program product, that when run on a processing unit of the wireless device, causes the wireless device to perform the method. The embodiments disclosed herein further relate to scheduling radio bearers to the wireless device. In order to obtain such scheduling there is provided a core network node, a method performed by the core network node, and a computer program comprising code, for example in the form of a computer program product, that when run on a processing unit of the core network node, causes the core network node to perform the method.

Fig. 4a schematically illustrates, in terms of a number of functional units, the components of a wireless device 19 according to an embodiment. A processing unit 21 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate arrays (FPGA) etc., capable of executing software instructions stored in a computer program product 41a (as in Fig. 6), e.g. in the form of a storage medium 23. Thus the processing unit 21 is thereby arranged to execute methods as herein disclosed. The storage medium 23 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The wireless device may further comprise a communications interface 22 for communications with a radio access network node. As such the communications interface 22 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of antennas for wireless communications. The processing unit 21 controls the general operation of the wireless device e.g. by sending data and control signals to the communications interface 22 and the storage medium 23, by receiving data and reports from the

communications interface 22, and by retrieving data and instructions from the storage medium 23. Other components, as well as the related

functionality, of the wireless device are omitted in order not to obscure the concepts presented herein.

Fig. 4b schematically illustrates, in terms of a number of functional modules, the components of a wireless device 19 according to an embodiment. The wireless device of Fig. 2b comprises a number of functional modules; an acquire module 21a configured to perform below step S104, and a control module 21b configured to perform below step S106. The wireless device of Fig. 4b may further comprises a number of optional functional modules, such as a transmit and/or receive module 21c configured to perform any of below steps S102, Si04a, Si04b, S108, and S110. The functionality of each

functional module 2ia-c will be further disclosed below in the context of which the functional modules 2ia-c may be used. In general terms, each functional module 2ia-c may be implemented in hardware or in software. Preferably, one or more or all functional modules 2ia-c may be implemented by the processing unit 21, possibly in cooperation with functional units 22 and/or 23. The processing unit 21 may thus be arranged to from the storage medium 23 fetch instructions as provided by a functional module 2ia-c and to execute these instructions, thereby performing any steps as will be disclosed hereinafter.

Fig. 5a schematically illustrates, in terms of a number of functional units, the components of a core network node 15 according to an embodiment. A processing unit 31 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate arrays (FPGA) etc., capable of executing software instructions stored in a computer program product 41b (as in Fig. 6), e.g. in the form of a storage medium 33. Thus the processing unit 31 is thereby arranged to execute methods as herein disclosed. The storage medium 33 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The core network node may further comprise a communications interface 32 for communications with other nodes in the core network, as well as with the radio access network 11. As such the communications interface 32 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline communications. The processing unit 31 controls the general operation of the core network node e.g. by sending data and control signals to the communications interface 32 and the storage medium 33, by receiving data and reports from the communications interface 32, and by retrieving data and instructions from the storage medium 33. Other components, as well as the related functionality, of the core network node are omitted in order not to obscure the concepts presented herein. The core network node may be embodied either as an MME or an SGSN.

Fig. 5b schematically illustrates, in terms of a number of functional modules, the components of a core network node 15 according to an embodiment. The core network node of Fig. 5b comprises a number of functional modules; an acquire module 31a configured to perform below step S204, and a control module 31b configured to perform below step S206. The core network node of Fig. 5b may further comprises a number of optional functional modules, such as a transmit and/or receive module 21c configured to perform any of below steps S202, S204a, and 8204b. The functionality of each functional module 3ia-c will be further disclosed below in the context of which the functional modules 31a -c may be used. In general terms, each functional module 3ia-c may be implemented in hardware or in software. Preferably, one or more or all functional modules 31a -c may be implemented by the processing unit 31, possibly in cooperation with functional units 32 and/or 33. The processing unit 31 may thus be arranged to from the storage medium 33 fetch instructions as provided by a functional module 31a -c and to execute these instructions, thereby performing any steps as will be disclosed hereinafter.

Fig. 6 shows one example of a computer program product 41a, 41b

comprising computer readable means 43. On this computer readable means 43, a computer program 42a can be stored, which computer program 42a can cause the processing unit 21 and thereto operatively coupled entities and devices, such as the communications interface 22 and the storage medium 23, to execute methods according to embodiments described herein. The computer program 42a and/or computer program product 41a may thus provide means for performing any steps of the wireless device as herein disclosed. On this computer readable means 43, a computer program 42b can be stored, which computer program 42b can cause the processing unit 31 and thereto operatively coupled entities and devices, such as the communications interface 32 and the storage medium 33, to execute methods according to embodiments described herein. The computer program 42b and/or computer program product 41b may thus provide means for performing any steps of the core network node as herein disclosed.

In the example of Fig. 6, the computer program product 41a, 41b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 41a, 41b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 42a, 42b is here schematically shown as a track on the depicted optical disk, the computer program 42a, 42b can be stored in any way which is suitable for the computer program product 41a, 41b.

Figs. 7 and 8 are flow charts illustrating embodiments of methods for controlling monitoring of radio bearers of a wireless device as performed by the wireless device. Figs. 9 and 10 are flow charts illustrating embodiments of methods for scheduling radio bearers to a wireless device as performed by the core network node. The methods are advantageously provided as computer programs 42a, 42b.

Reference is now made to Fig. 7 illustrating a method for controlling monitoring of radio bearers of a wireless device as performed by the wireless device according to an embodiment. The monitoring of the radio bearers of the wireless device is performed when the wireless device is in connected mode.

S104. The wireless device is configured to acquire timing information indicating network reachability of the wireless device. This timing

information can by the wireless device be used for power saving purposes. S106. The wireless device is configured to control monitoring of radio bearers of the wireless device selectively between a first state and a second state. The control is thus performed such that the monitoring is performed selectively in the first state and the second state, respectively. Different examples of how the monitoring may be performed in the first state and in the second state, respectively, will be disclosed below. The controlling is based on the timing information acquired in step S104. The controlling in step S106 is performed for power saving of the wireless device.

The connected mode may be a radio resource control (RRC) connected mode.

Embodiments relating to further details of controlling monitoring of radio bearers of a wireless device as performed by the wireless device will now be disclosed.

There may be different kinds of first state and second state, respectively. Different embodiments relating thereto will now be described in turn.

The states may relate to different kinds of power saving of the wireless device. Particularly, the first state may be a power saving state and the second state may be a non-power saving state. In the first state, the radio bearers may be monitored according to an enhanced power saving mode (ePSM). An example of an ePSM procedure has been outlined above. In the second state, the radio bearers may be monitored using other existing procedures, such as discontinuous reception (DRX), no DRX, or long DRX.

There may be different ways for the wireless device to monitor the radio bearers. For example, the monitoring of radio bearers may comprise monitoring reception of downlink packets.

There may be different ways for the wireless device to acquire the timing information. Different embodiments relating thereto will now be described in turn.

According to one embodiment the timing information is provided by an inter arrival time indicator Tiat. In general terms, while being in the RRC connected mode, the wireless device may run a packet inter arrival timer. The wireless device may perform the monitor according to existing procedures (such as no DRX, DRX, long DRX) if the packet inter arrival timer does not expire (i.e. it does not reach the inter arrival time indicator Tiat. If the packet inter arrival timer expires (i.e. it reaches the inter arrival time indicator Tiat) the wireless device monitor reception of downlink packets according to ePSM. According to this embodiment the first state is thus entered if the inter arrival time indicator Tiat expires before a packet is received by the wireless device. According to this embodiment the second state is thus entered or maintained if a packet is received by the wireless device before expiration of the inter arrival time indicator Tiat, and a timer being associated with the Tiat indicator being reset at packet reception.

According to one embodiment the timing information is provided by an indication that the wireless device is moved to or from a paging channel (PCH). This information may be provided in form of the RRC connected mode states denoted cell_PCH (Cell Paging channel) and URA_PCH (URA Paging channel), where URA is short for Universal Terrestrial Radio Access Network registration Area. According to this embodiment the first state is entered if the wireless device is moved to PCH. According to this embodiment the second state is entered or maintained if the wireless device is moved from the paging channel for example to a dedicated channel (DCH) or a forward access channel (FACH).

Figure 13 schematically illustrates states of a wireless device regarding which monitoring state it should enter based on received timing information; if the Tiat expiries or if the wireless device is moved to the PCH, the radio bearers are monitored according ePSM, otherwise the radio bearers are monitored using DRX, no DRX, or long DRX.

There may be different nodes from which the wireless device may acquire the timing information. Different embodiments relating thereto will now be described in turn. According to one embodiment the timing information is received from a node in the core network. Particularly, the timing

information may be received from a core network node, such as an MME or an SGSN. According to one embodiment the timing information is received from a node in the radio access network. Particularly, the timing information may be received from a radio access network node, such as a radio network controller, RNC. The RNC may provide the timing information by an indication that the wireless device is moved to or from the PCH. In general terms, and as is clear from the schematic illustration in Figure 3, the wireless device has no direct connection to the core network. Thus, that the timing information is received from a node in the core network should be

interpreted as the node in the core network providing the timing information to the wireless device via the radio access network.

Reference is now made to Fig. 8 illustrating methods for controlling monitoring of radio bearers of a wireless device as performed by the wireless device according to further embodiments.

The value of the inter arrival time indicator Tiat may be negotiated with another network node, such as the core network node. Particularly, a negotiated inter arrival time indicator Tiatn defining the timing information may be provided according to optional steps S102 and Si04a.

S102. The wireless device may be configured to transmit a Tracking Area Update (TAU) request or a Routing Area Update (RAU) request or an Attach request to the core network node. The TAU request or RAU request comprises a proposed inter arrival time indicator Tiat.

Si04a. The wireless device may be configured to receive a TAU accept or RAU accept or an Attach accept from the core network node. The TAU accept or RAU accept or Attach accept comprises a negotiated inter arrival time indicator Tiatn. The negotiated inter arrival time indicator Tiatn defines the timing information.

The TAU request or RAU request or Attach request may further comprise further proposed timing information. For example, the TAU request or RAU request or Attach request may further comprise a proposed absolute clock reference Tref, a proposed idle mode sojourn time Ti, and a proposed power saving mode sojourn time Tp. The TAU accept or RAU accept or Attach accept may then further comprise a negotiated absolute clock reference Trefn, a negotiated idle mode sojourn time Tin, and a negotiated power saving mode sojourn time Tpn. l8

That is, according to one embodiment the wireless device proposes values for Tref, Ti, and Tp to the core network node, and the core network node selects the values for these parameters to be used, denoted Trefn, Tin, and Tp, and returns these values to the wireless device. As note above, the timing information may be provides by the wireless device 19 being moved to or from the PCH. Therefore:

Si04b. The wireless device may be configured to acquire an indication that the wireless device is moved to or from the PCH, wherein the timing information is defined by this indication. There may be different ways for the wireless device to act once having acquired the timing information (in addition to controlling monitoring of radio bearers). For example, the wireless device may, after having acquired the timing information and the negotiated values Trefn, Tin, and Tp communicate these values to another node in the core network or in the service network, for example to the AS, as in optional steps S108, S110.

S108. The wireless device may be configured to transmit information regarding the negotiated absolute clock reference Trefn, the negotiated idle mode sojourn time Tin, and the negotiated power saving mode sojourn time Tpn to the AS, and/or the SGW of the wireless device. Advantageously, this provides a simple mechanism for retrieval of time values for the AS using direct wireless device to AS communication. No signaling interface with the operator is required.

S110. The wireless device may be configured to transmit information regarding the negotiated inter arrival time indicator Tiatn to the AS, and/or the SGW of the wireless device, for example by means of the core network node.

Reference is now made to Fig. 9 illustrating a method for scheduling radio bearers to a wireless device as performed by the core network node according to an embodiment. The scheduling of the radio bearers to the wireless device is performed when the wireless device is in connected mode. The core network node has a radio access network interface.

S204. The core network node is configured to acquire timing information indicating network reachability of the wireless device. This timing information can by the wireless device be used for power saving purposes.

S206. The core network node is configured to control scheduling of radio bearers to the wireless device selectively between a first state and a second state. The control of the scheduling is thus performed such that the scheduling is performed selectively in the first state and the second state, respectively. Different examples of how the scheduling may be performed in the first state and in the second state, respectively, will be disclosed below. The controlling is based on the timing information acquired in step S204. The controlling in step S206 is performed for power saving of the wireless device.

As noted above, the connected mode may be a radio resource control (RRC) connected mode.

Embodiments relating to further details of scheduling radio bearers to a wireless device will now be disclosed. There may be different kinds of first state and second state, respectively. Different embodiments relating thereto will now be described in turn. In general terms, the states of the scheduling as performed by core network node may correspond to the states of the monitoring as performed by the wireless device. Hence, in the first state radio bearers may be scheduled according to ePSM; in the second state radio bearers may be scheduled using other existing procedures, such as DRX, no DRX, or long DRX.

There may be different ways for the core network node to control the scheduling of radio bearers. For example, the control of scheduling of radio bearers may comprise scheduling of transmission of downlink packets to the wireless device.

There may be different ways for the core network node to acquire the timing information. Different embodiments relating thereto will now be described in turn.

As disclosed above, according to one embodiment the timing information is provided by an inter arrival time indicator Tiat. In general terms, the core network node may run a packet inter arrival timer. The core network node may perform the scheduling according to existing procedures, i.e. forwarding user plane packets to the RAN, where the RAN performs scheduling according to existing RAN procedures (such as no DRX, DRX, long DRX), if the packet inter arrival timer does not expire (i.e. it does not reach the inter arrival time indicator Tiat. If the packet inter arrival timer expires (i.e. it reaches the inter arrival time indicator Tiat) the core network node schedules transmission of downlink packets according to ePSM. According to this embodiment, the first state is entered if the inter arrival time indicator Tiat expires before a packet scheduled to the wireless device is received by the core network node. According to this embodiment, the second state is entered or maintained if a packet scheduled to the wireless device received by the core network node before expiration of the inter arrival time indicator

Tiat, and a timer being associated with the Tiat indicator being reset at packet reception.

As disclosed above, according to one embodiment the timing information is provided by an indication that the wireless device is moved to or from the PCH. According to this embodiment the first state is entered if the wireless device is moved to PCH. According to this embodiment the second state is entered or maintained if the wireless device is moved from the paging channel for example to a dedicated channel (DCH) or a forward access channel (FACH). The RNC may send an update, for example via interface Iu, to the core network node when the wireless device is moved to (or from) the PCH.

Hence, for this embodiment the timing information may be received from a radio access network node, such as the RNC. The RNC may forward this information directly to the SGW (acting as the core network node) via the S12 interface.

Figure 14 schematically illustrates a decision tree for a core network node regarding which scheduling state it should enter based on received timing information; downlink packets of the radio bearers are scheduled according to ePSM if the inter arrival time indicator Tiat expires before a packet scheduled to the wireless device is received by the core network node or if the wireless device enters the PCH.

Reference is now made to Fig. 10 illustrating methods for scheduling radio bearers to a wireless device as performed by the core network node according to further embodiments.

The value of the inter arrival time indicator Tiat may be proposed by the wireless device and then negotiated (and determined as a negotiated inter arrival time indicator Tiatn defining the timing information) by the core network node, according to optional steps S202 and S204a. S202. The core network node may be configured to receive a TAU request or a RAU request or an Attach request from the wireless device. The TAU request or RAU request or Attach request comprises a proposed inter arrival time indicator Tiat.

S204a. The core network node may be configured to transmit a TAU accept or a RAU accept or Attach accept to the wireless device. The TAU accept or RAU accept or Attach accept comprises a negotiated inter arrival time indicator Tiatn. The negotiated inter arrival time indicator Tiatn defines the timing information. As disclosed above, the TAU request or RAU request or Attach request may further comprise further proposed timing information Tref, Ti, and Tp, and the TAU accept or RAU accept or Attach accept may further comprise further negotiated timing information Trefn, Tin, and Tpn. The core network node may be configured to inform the SGW (acting as a core network mobility anchor node) of the determined proposed timing information Tref, Ti, and Tp.

As note above, the timing information may be provides by the wireless device 19 being moved to or from the PCH. Therefore: S204b. The core network node may be configured to acquire an indication that the wireless device is moved to or from the PCH, wherein the timing information is defined by this indication.

A first particular embodiment for controlling monitoring radio bearers of a wireless device and scheduling radio bearers to the wireless device based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signalling call flow according to Figure 11. In this first particular embodiment the core node mobility node may be an MME. In this first particular embodiment the radio access network is represented by a network node 12 in the form of an eNB. 501. The wireless device transmits a TAU request or an Attach request to the core network node. The request (TAU or Attach) may comprise a proposal for the time values Ti, Tp, Tref and Tiat. The request (TAU or Attach) may additionally or alternatively comprise a maximum latency time value.

502. The core network node determines the time values to use based on operator policies, node specific policies, received parameters from the wireless, including any time values (such as Ti, Tp, Tref, Tiat), any received maximum latency time value from the wireless device, wireless device information in the core network node, such as statistics collected for the wireless device, and other network status. The core network node returns decided negotiated time values (such as Tin, Tpn, Trefn, Tiatn) to the wireless in e.g. a TAU Accept or an Attach Accept.

503. The core network node may, optionally, transmit the timing information received from the core network node (Tin, Tpn, Trefn, Tiatn) to the SGW (or PGW).

504. The SGW (or PGW) may, optionally, transmit an acknowledgement of having received the timing information to the core network node.

Alternatively, the information in steps 503 and 504 may be sent in step 505, either by the core network node or by the wireless device. 505. The wireless device establishes at least one bearer to communicate with the AS. The core network node may provide the timing information to the SGW.

506. The negotiated time values (Tin, Tpn, Trefn, Tian) may by the wireless device be passed to the AS. An application specific protocol or some other protocol used for communication between the wireless device and the AS may be used for the transmission of these time values.

507. The AS may optionally acknowledge the received time values.

The AS may initiate and transmit mobile terminated (MT) data when the wireless device is active and reachable. The AS calculates the point in time when to transmit the data using the received time values. The AS has a clock which is synchronized with the wireless device and the core network node based on the Trefn value and an external reference clock e.g. GPS, UTM, or NTP server, etc.

A second particular embodiment for controlling monitoring radio bearers of a wireless device and scheduling radio bearers to the wireless device based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signalling call flow according to Figure 12. In this second particular embodiment the core node mobility node may be an SGSN. In this second particular embodiment the radio access network is represented by the RNC 13.

601. The wireless device transmits a RAU request or an Attach request to the core network node. The request (RAU or Attach) may comprise a proposal for the time values Ti, Tp, and Tref. The request (TAU or Attach) may

additionally or alternatively comprise a maximum latency time value.

602. The core network node determines the time values to use based on operator policies, node specific policies, received parameters from the wireless, including any time values (such as Ti, Tp, Tref), any received maximum latency time value from the wireless device, wireless device information in the core network node, such as statistics collected for the wireless device, and other network status. The core network node returns decided negotiated time values (such as Tin, Tpn, Trefn) to the wireless in e.g. a RAU Accept or an Attach Accept. 603a. An RRC and Iu connection is established. During the establishment (e.g. in an INITIAL UE MESSAGE) the RNC includes information that the RNC supports providing UTRA state updates to the SGSN (e.g. that the wireless device enters URA_PCH or cell_PCH). The SGSN includes a support indication for the UTRA state update information to the RNC in a subsequent Iu message sent to the RNC (not shown in the Figure 12). core network nodecore network node

603b. The wireless device is in connected state (DCH or FACH).

603c. The RNC decides to put the wireless device into a PCH state

(CELL_PCH or URA_PCH). The RNC therefore includes an RRC State Indicator with the value set to CELL_PCH or URA_PCH in an RRC Message e.g. PHYSICAL CHANNEL RECONFIGURATION, RADIO BEARER

RECONFIGURATION, RADIO BEARER SETUP, TRANSPORT CHANNEL RECONFIGURATION. 604a. If the SGSN has indicated support for UTRA state update information during setup of the Iu connection (see, step 603a), then the RNC indicates to the SGSN that the wireless devie has been put into URA or PCH state in an Iu Message (either in an existing Iu message or in a new Iu message). 604b. The SGSN acknowledges reception of the Iu message to the RNC.604C. If the SGW acts as an anchor node then the SGSN updates the SGW with the new state.

6o4d. The SGW acknowledges reception of the state update. core network nodecore network node6o5. At some point in time (after step 602) the wireless device may provide the negotiated time values (Tin, Tpn, Trefn) to the AS, for example in a Synch Establishment. An application specific protocol or some other protocol used for communication between the wireless device and the AS may be used for the transmission of these time values. 606. The AS may optionally acknowledge the received time values, for example in a Synch Establishment Acknowledgement.

The AS may initiate and transmit MT data when the wireless device is active and reachable. The AS calculates the point in time when to transmit the data using the received time values. The AS has a clock which is synchronized with the wireless device and the core network node (MME) based on the Trefn value and an external reference clock e.g. GPS, UTM, or NTP server, etc.

The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

1. A method for controlling monitoring radio bearers of a wireless device (19), the method being performed by a wireless device in connected mode, the method comprising:

acquiring (S104) timing information indicating network reachability of the wireless device; and

controlling (S106) monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

2. The method according to claim 1, wherein the first state is a power saving state and wherein the second state is a non-power saving state.

3. The method according to any one of the preceding claims, wherein in the first state radio bearers are monitored according to an enhanced power saving mode, ePSM.

4. The method according to any one of the preceding claims, wherein in the second state radio bearers are monitored using discontinuous reception, DRX, no DRX, or long DRX.

5. The method according to any one of the preceding claims, wherein said monitoring of radio bearers comprises monitoring reception of downlink packets.

6. The method according to any one of the preceding claims, wherein the timing information is received from a core network node (15), such as a mobility management entity, MME, or a serving GPRS support node, SGSN.

7. The method according to any one of the preceding claims, wherein the timing information is received from a radio access network node (12, 13), such as a radio network controller, RNC.

8. The method according to any one of the preceding claims, wherein the timing information is provided by an inter arrival time indicator Tiat.

9. The method according to claim 8, wherein the first state is entered if the inter arrival time indicator Tiat expires before a packet is received by the wireless device.

10. The method according to claim 8, wherein the second state is entered or maintained if a packet is received by the wireless device before expiration of the inter arrival time indicator Tiat, and a timer being associated with the Tiat indicator being reset at packet reception.

11. The method according to any one of the preceding claims, further comprising:

acquiring (Si04b) an indication that the wireless device is moved to or from a paging channel, PCH, and wherein the timing information is defined by said indication.

12. The method according to claim 11, wherein the first state is entered if the wireless device is moved to the paging channel, PCH.

13. The method according to claim 11, wherein the second state is entered or maintained if the wireless device is moved from the paging channel, PCH, for example to a dedicated channel, DCH or a forward access channel, FACH.

14. The method according to any one of the preceding claims, further comprising:

transmitting (S102) a Tracking Area Update, TAU, request or a Routing

Area Update, RAU, request or an Attach request to a core network node, the TAU request or RAU request or Attach request comprising a proposed inter arrival time indicator Tiat; and

receiving (Si04a) a TAU accept or RAU accept or Attach accept from the core network node, the TAU accept or RAU accept or Attach accept comprising a negotiated inter arrival time indicator Tiatn, wherein the negotiated inter arrival time indicator Tiatn defines said timing information .

15. The method according to claim 14, wherein the TAU request or RAU request or Attach request further comprises a proposed absolute clock reference Tref, a proposed idle mode sojourn time Ti, and a proposed power saving mode sojourn time Tp, and wherein the TAU accept or RAU accept or Attach accept further comprises a negotiated absolute clock reference Trefn, a negotiated idle mode sojourn time Tin, and a negotiated power saving mode sojourn time Tpn.

16. The method according to claim 15, further comprising:

transmitting (S108) information regarding the negotiated absolute clock reference Trefn, the negotiated idle mode sojourn time Tin, and the negotiated power saving mode sojourn time Tpn to at least one of an application server, AS, and a serving gateway, SGW, of the wireless device.

17. The method according to claim 14, 15 or 16, further comprising:

transmitting (S110) information regarding the negotiated inter arrival time indicator Tiatn to at least one of an application server, AS, and a serving gateway, SGW, of the wireless device.

18. The method according to any one of the preceding claims, wherein the connected mode is radio resource control, RRC, connected mode.

19. A method for scheduling radio bearers to a wireless device (19), the method being performed by a core network node (15) having a radio access network interface, the method comprising:

acquiring (S204) timing information indicating network reachability of a wireless device in connected mode; and

controlling (S206) scheduling of radio bearers to the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

20. The method according to claim 19, wherein in the first state radio bearers are scheduled according to an enhanced power saving mode, ePSM.

21. The method according to any one of claims 19 to 20, wherein in the second state radio bearers are scheduled using discontinuous reception, DRX, no DRX, or long DRX.

22. The method according to any one of claims 19 to 21, wherein said controlling scheduling of radio bearers comprises scheduling of transmission of downlink packets to the wireless device.

23. The method according to any one of claims 19 to 22, wherein the timing information is received from a radio access network node, such as a radio network controller, RNC.

24. The method according to any one of claims 19 to 23, wherein the timing information is provided by an inter arrival time indicator Tiat.

25. The method according to claim 24, wherein the first state is entered if the inter arrival time indicator Tiat expires before a packet scheduled to the wireless device is received by the core network node.

26. The method according to claim 24, wherein the second state is entered or maintained if a packet scheduled to the wireless device received by the core network node before expiration of the inter arrival time indicator Tiat, and a timer being associated with the Tiat indicator being reset at packet reception.

27. The method according to any one of claims 19 to 26, further comprising: acquiring (S204b) an indication that the wireless device is moved to or from a paging channel, PCH, and wherein the timing information is defined by said indication.

28. The method according to claim 27, wherein the first state is entered if the wireless device is moved to the paging channel, PCH.

29. The method according to claim 27, wherein the second state is entered if the wireless device is moved from the paging channel, PCH, for example to a dedicated channel, DCH or a forward access channel, FACH.

30. The method according to any one of claims 19 to 29, further comprising: receiving (S202) a Tracking Area Update, TAU, request or a Routing

Area Update, RAU, request or an Attach request from the wireless device, the TAU request or RAU request or Attach request comprising a proposed inter arrival time indicator Tiat; and

transmitting (204a) a TAU accept or a RAU accept or Attach accept to the wireless device, the TAU accept or RAU accept or Attach accept comprising a negotiated inter arrival time indicator Tiatn, wherein the negotiated inter arrival time indicator Tiatn defines said timing information.

31. The method according to claim 30, wherein the TAU request or RAU request or Attach request further comprises a proposed absolute clock reference Tref, a proposed idle mode sojourn time Ti, and a proposed power saving mode sojourn time Tp, and wherein the TAU accept or RAU accept or Attach accept further comprises a negotiated absolute clock reference Trefn, a negotiated idle mode sojourn time Tin, and a negotiated power saving mode sojourn time Tpn.

32. A wireless device (19) for controlling monitoring radio bearers of the wireless device in connected mode, the wireless device comprising a processing unit (21), the processing unit being configured to cause the wireless device to:

acquire timing information indicating network reachability of the wireless device; and

control monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

33. A core network node (15) for scheduling radio bearers to a wireless device (19), the core network node having a radio access network interface and comprising a processing unit (31), the processing unit being configured to cause the core network node to:

acquire (S104) timing information indicating network reachability of a wireless device in connected mode; and

control (S106) scheduling of radio bearers to the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

34. The core network node according to claim 33, wherein the core network node is a mobility management entity, MME, a serving general packet radio service support node, SGSN, or a serving gateway, SGW.

35. A computer program (42a) for controlling monitoring radio bearers of a wireless device in connected mode, the computer program comprising computer code which, when run on a processing unit (21) of the wireless device, causes the wireless device to:

acquire (S204) timing information indicating network reachability of the wireless device; and

control (S206) monitoring of radio bearers of the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

36. A computer program (42b) for scheduling radio bearers to a wireless device, the computer program comprising computer code which, when run on a processing unit (31) of a core network node (15) having a radio access network interface, causes the core network node to:

acquire timing information indicating network reachability of a wireless device in connected mode; and

control scheduling of radio bearers to the wireless device selectively between a first state and a second state based on the timing information for power saving of the wireless device.

37. A computer program product (41a, 41b) comprising a computer program (42a, 42b) according to at least one of claims 35 and 36, and a computer readable means (43) on which the computer program is stored.