GB2504541A

GB2504541A - Selecting a different radio access technology in order to achieve power savings

Info

Publication number: GB2504541A
Application number: GB1213787.3A
Authority: GB
Inventors: Brian Alexander Martin; Keiichi Kubota; Tero Henttonen; Jari Isokangas; Samuli Turtinen; Wei Bai
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2012-08-02
Filing date: 2012-08-02
Publication date: 2014-02-05
Also published as: WO2014020560A1; GB201213787D0

Abstract

A wireless device operates under network control. The wireless device operates using a first radio access technology under control of a network control apparatus 204. The wireless device determines that using a different radio access technology would consume less power 210. The wireless device signals to the network control apparatus that it would like to use the different radio access technology in order to achieve power savings 220 (e.g. by sending a SIGNALLING CONNECTION RELEASE INDICATION (SCRI) message). When the network receives a request to use a different radio access technology in order to achieve power savings at the wireless device, the network transmits a signal that at least one of: (i) redirects the wireless device to the different radio access technology in response to receipt by the network control apparatus of the signalling from the wireless device; (ii) changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority; and (iii) hands over the wireless device to a cell that uses the different radio access technology. The wireless device may monitor power consumption over time for different applications running on the device or for different activity states of the device.

Description

tM:;: INTELLECTUAL .*.. PROPERTY OFFICE Application No. 0B1213787.3 RTM Date:8 Novcnibcr 2012 The following terms are registered trademarks and should be read as such wherever they occur in this document: Skype YouTube Intellectual Properly Office is an operaling name of Ihe Patent Office www.ipo.gov.uk WIRELESS DEVICES, METHODS AND

APPARATUS AND COMPUTER PROGRAMS THEREFOR

Technical Field

S The present invention relates to a method of operating a wireless device, apparatus for a wireless device, a method of operating a network control apparatus, apparatus for a network control apparatus, and computer programs therefor.

Background

The following abbreviations arc uscd in thc present specification: 3GPP Third Generation Partnership Project CPC Continuous Packet Connectivity DRX discontinuous reception eNB evolved Node B EUTRAN Evolved UTRAN ED Fast Dormancy GERAN GSM-Enhanced Data Rates for Global Evolution (EDGE) RAN GPS Global Positioning System GSM Global System for Mobile Communications IDC in-device coexistence LTE Long Tcrm Evolution PS packet switched RAN radio access network RAT radio access technology RF radio frequency RRC radio resource control SCRI signalling connection release indication UE user equipment UMTS Universal Mobile Telecommunications System URA user registration area UTRAN Universal Terrestrial Radio Access Network Wireless networks have in recent years experienced a considerable increase in the amount of data being transmitted to and from wirelessly connected devices or S "user equipment" (UE). The traffic characteristics of this data traffic are very different from that of traditional mobile phones, and can be characterised by its use of a lot of background signalling and bursty traffic consisting of relatively small data packets. The introduction of machine-type communications to the networks can also bc expected to follow this trend. As a result, wireless networks need to implement new mechanisms to cope with this new traffic and make efficient use of the available resources while providing high capacity and throughputs and minimum delays. Of particular concern in improving the support of this low volume, bursty data is minimising the signalling load on the network and improving the power consumption of the user equipment.

In general, in many types of wireless systems, the user equipment is typically in one of a number of predefined activity states. These may be for example an idle state, a paging state in which the user equipment checks a paging channel for incoming paging messages at predefmed time intervals and has an RRC (Radio Resource Control) connection, and one or more data connection states in which the user equipment can actively transmit and receive data. In general, these states use increasingly more power at the user equipment and also more network signalling. In order to minimise power consumption, particularly to maximise battery life before recharging is required, the user equipment is often caused to operate in a state having a low or the lowest power consumption possible, depending on for example the operational demands of the user equipment and/or network requirements. A particular concern from the perspective of the wireless network operator is to keep down the amount of control signals that have to be passed to and from the user equipment in order to cause the user equipment to transition between states, and/or to allow the user equipment to send or receive data, and/or to locate the user equipment.

As a particular example, Fast Dormancy (FD) is a 3GPP (Third Generation Partnership Project) feature specified from Release S for UMTS (Universal Mobile Telecommunications System) which allows the UE to request that the network reconfigure the UE into a more power efficient state by the IJE indicating that packet S data transfer has ended. This feature allows the UE to optimise the power consumption particularly during bursty packet data transfer, which is a typical characteristic of the data activity of smart phones. To initiate Fast Dormancy, the UE sends a SIGNALLING CONNECTION RELEASE INDICATION (SCRI) message to the network. This mcssagc triggcrs the network to send a signal to the IJE to cause the UE to move into a more power efficient state, which effectively provides the network with control over this procedure. The focus of this approach to date has been on the UE being moved to a state that has a longer DRX (discontinuous reception) period or to provide a configuration for the FE that has longer DRX and/or faster inactivity timers. Tn DRX, in simple terms, during inactive periods the UE enters a low power state (which may be for example an IDLE state) in which inter alia its receiver is turned off to save power, with the UE periodically "waking" and moving to some connected state in which it can receive signals from the network. Likewise, in LTE (Long Term Evolution), the UE is again able to indicate to the network that it would like to be moved to a state or configuration that uses less power.

By way of further background, in LTE Release 11 there is provision for "in-device coexistence" or IDC. A TiE may be equipped with for example LTE, WiFi, and Bluetooth transceivers. Due to the extreme proximity of multiple radio transceivers within the same liE, the transmit power of one transmitter may be much higher than the received power level of another receiver. It can happen that different radio technologies within the same liE operating on adjacent or similar frequencies can cause severe interference to each other. There are a number of proposals for dealing with this, including changing the frequency used by at least one of the radio technologies if interference occurs, changing the timing of transmissions, and changing the DRX periods.

Summary

According to a first aspcct of thc prescnt invention, them is providcd a mcthod of operating a wireless device under network control, the method comprising: the wireless device operating using a fir st radio access technology under S control of a network control apparatus; the wireless device determining that using a different radio access technology the wireless device signalling to the network control apparatus that it would like to usc the different radio acccss tecimology in order to acbievc power savings.

This allows a wireless device to indicate to a network control apparatus (often simply referred to as "the network" by convention in this field) its preference to move to using another radio acccss tcclmology in ordcr to opcratc in a more powcr efficient way. In cxamplcs, various criteria may bc used by thc wirclcss devicc to makc thc determination that using a different radio access technology would consume less power.

In an embodiment, the wireless device signals to the network control apparatus plural different radio access technologies that it would like to use in order of proference in order to achieve power savings.

In an embodiment, the wireless device monitors power consumption over time when using the first radio access technology and when using a different radio access technology so as to be able to determine that using the different radio access technology would consume less power. In an embodiment, the wireless device monitors power consumption over time for different applications running on the wireless device. These embodiments enable the wireless device to effectively "learn" which radio access technology provides or is most likely to provide the most power-efficient operation. This thus allows for the fact that for example different applications running on the wireless device may consume different amounts of power, and will do differently according to thc particular usage by the user of the wireless device.

In an embodiment, the wireless device monitors power consumption over time S for different activity states of the wireless device.

In an embodiment, the wireless device estimates power consumption based on network configuration, or the wireless device configuration, or the network configuration and the wireless device configuration.

In an embodiment, the first radio access technology is Universal Mobile Telecommunications System (UMTS), the wireless device signalling to the network control apparatus that it would like to usc the different radio access technology in order to achieve power savings by sending a SIGNALLING CONNECTTON RELEASE INDICATION message to the network control apparatus, the SIGNALLING CONNECTION RELEASE INDICATION message including an indication that the wireless device wants to use a different radio access technology and a cause indicative of power saving. The different radio access technology may be at least one of Long Term Evolution Evolved Universal Terrestrial Radio Access Network (LTE EUTRAN), Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network (GERAN), and Universal Terrestrial Radio Access Network (U'TRAN. Other RATs may also be selected.

In an embodiment, the first radio access technology is Long Term Evolution Evolved Universal Terrestrial Radio Access Network (LTE EUTRAN) and the different radio access technology is at least one of Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network (GERAN), and Universal Terrestrial Radio Access Network (III RAN).

In an embodiment, the wireless device receives from the network control apparatus a signal redirecting the wireless device to use the different radio access technology in response to receipt by the network control apparatus of the signalling from the wireless device.

In an embodiment, the wireless device receives from the network control apparatus a signal that changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority.

In an embodiment, the wireless device is handed over by the network control apparatus to a cell that uses the different radio access technology.

According to a second aspect of the present invention, there is provided apparatus comprising a processing system for a wireless device, the processing system being constructed and arranged to: cause the wireless device to operate using a first radio access technology under control of a network control apparatus; determine if using a different radio access technology would consume less power; and cause the wireless device to signal to said network control apparatus that it would like to use the different radio access technology in order to achieve power savings.

According to a third aspect of the present invention, there is provided a computer program for a wireless device, the computer program comprising instructions such that when the computer program is executed on a processing system of the wireless device, the wireless device is arranged to: operate using a first radio access technology under control of a network control apparatus; determine if using a different radio access technology would consume less power; and signal to said network control apparatus that it would like to use thc diffcrcnt radio access technology in order to achieve power savings.

According to a fourth aspect of the present invention, there is provided a S method of operating a network control apparatus, the method comprising: receiving, from a wireless device operating using a first radio access technology, a request to use a different radio access technology in order to achieve power savings at the wireless device; and in response thereto: transmitting a signal that at icast one of: redirects thc wireless dcvice to the different radio access technology in response to receipt by the network control apparatus of the signalling from the wireless device; changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority; and hands over the wireless device to a cell that uses the different radio access technology.

According to a fifth aspect of the present invention, there is provided apparatus comprising a processing system for a network control apparatus, the processing system being constructed and arranged to: upon receipt from a wireless device of a request to use a different radio access technology in order to achieve power savings at said wireless device, cause the network control apparatus to transmit a signal that at least one of: redirects said wireless device to use the different radio access technology; changes cell reselection priorities of said wireless device such that the different radio access technology has a higher priority; and hands over the wireless device to a cell that uses the different radio access technology.

According to a sixth aspect of the present invention, there is provided a computer program for a network control apparatus, the computer program comprising

S

instructions such that when the computer program is executed on a processing system of the network control apparatus, the network control apparatus is arranged to: upon receipt from a wireless device of a request to use a different radio access technology in order to achieve power savings at said wireless device, transmit a signal S that at least one of: redirects said wireless device to use the different radio access technology; changes cell reselection priorities of said wireless device such that the different radio access technology has a higher priority; and hands ovcr the wireless device to a cell that uses the different radio access technology.

There may be provided a non-transitory computer-readable storage medium comprising a set of computer-readable instructions stored thereon, which, when executed by a processing system, cause the processing system to carry out a method as described above.

The processing systems described above may comprise at least one processor and at least one memory including computer program instructions, the at least one memory and the computer program instructions being configured to, with the at least one processor, cause the apparatus at least to perform as described above.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the DrawinQs

Figure 1 shows schematically a wireless device operating in a cellular network serviced by abase station; Figure 2 shows a schematic flow diagram for an example of one embodiment of the present invention; and Figure 3 shows a schematic flow diagram for an example of another embodiment of the present invention.

S Detailed Description

"Wireless devices" include in general any device capable of connecting wirelessly to a network, and includes in particular mobile devices including mobile or cell phones (including so-called "smart phones"), personal digital assistants, pagers, tablet and laptop computers, content-consumption or generation devices (for music and!or video for example), data cards, USB dongles, etc., as well as fixed or more static devices, such as personal computers, game consoles and other generally static entertainment devices, various other domestic and non-domestic machines and devices, etc. The term "user equipment" or UE is often used to refer to wireless devices in general, and particularly mobile wireless devices.

Figure 1 shows schematically a user equipment or wireless device, in this case in the form of a mobile phone/smartphone 1. The user equipment 1 contains the necessary radio module 2, processor(s) and memory/memories 3, antenna 4, etc. to enable wireless communication with the network. The user equipment 1 in use is in communication with a radio mast 5. As a particular example in the context of UMTS (Universal Mobile Telecommunications System), there may be a network control apparatus 6 (which may be constituted by for example a so-called Radio Network Controller) operating in conjunction with one or more Node Bs (which, in many respects, can be regarded as "base stations"). As another example, LTE (Long Term Evolution) makes usc of a so-called evolved Node B (eNB) where the RF transceiver and resource management/control functions are combined into a single entity. The term "base station" is used in this specification to include a "traditional" base station, a Node B, an evolved Node B (eNB), or any other access point to a network, unless the context requires otherwise. The network control apparatus 6 (of whatever type) may have its own processor(s) 7 and memory/memories 8, etc. Moreover for convenience and by convention, the terms "network", "network control apparatus" and "base station" will often be used interchangeably, depending on the context.

In general terms, wireless devices or UEs are in communication with each S other, and/or with the Internet, via a network. The particular wireless technology that is used for the connection between the network and the wireless devices is commonly referred to as the radio access technology or "RAT". Different RATs apply or conform to different wireless Standards, or in some eases different "releases" of a Standard. Examples of different RATs or implementations that use different RATs include GSM (Global System for Mobile Communications), GSM/EDGE (GSM-Enhanced Data Rates for Global Evolution), UMTS (Universal Mobile Telecommunications System or "3G"), and LTE (Long Term Evolution or "4G"), etc., amongst many others. Different RATs typically use one or more of different transmission frequencies and/or frequency bands, different modulation schemes, different protocols, etc. Depending on a number of factors, including for example the particular RATs concerned and/or the capabilities of the particular wireless device, a particular wireless device may be capable of using different RATs, with some wireless devices being able to use more than one RAT simultaneously. The term "RAT" or "radio access technology" as used in this manner is common and well

understood by those working in this field.

The following specific examples of embodiments of the present invention are given particularly in the context of 3GPP (Third Generation Partnership Project) UMTS (Universal Mobile Telecommunications System) and LTE EUTRAN (Long Term Evolution Evolved Universal Terrestrial Radio Access Network) systems.

However, the principles of the present invention are applicable to other wireless systems and RATs, operating according to different standards (including in at least some cases different releases within a standard) and protocols.

The system currently in use in 3GPP provides for a number of defined activity states for the user equipment, including an Idle state, a CELL PCH/URA PCH (paging channel) state, a CELL FACH (forward access channel) state, and a CELL DCH (dedicated channel) state. In the Idle state, the user equipment does not have an RRC (Radio Resource Control) connection and this is the state having the lowest power consumption. In the CELL PCH!URA PCH state, the user equipment S is again in a low power consumption state as it only periodically looks for incoming paging messages, and in this state does have a RRC connection. However, the user equipment needs to be in the CELL_FACH or CELL_DCH state in order to be able to perform both transmission and reception of data (including in particular "user" data, as opposed to data relating to control or management of the device and its network connection, etc. for example). In the CELL DCH state, a dedicated physical channel is allocated to the user equipment. In the CELL_FACH state, the user equipment shares the physical channel with other user equipment, though nevertheless may have a dedicated logical channel. As is well understood, a logical channel in this context is an information stream dedicated to the transfer of a specific type of information over the radio interface and corresponds to an individual signal which can be separated or isolated from an aggregate of signals which occupy the same physical bandwidth or channel. CELL FACH can be regarded as a transition state between the CELL PCH/TJRA PCH and CELL DCH states. Keeping the user equipment in CELL_FACH state improves power consumption for the user equipment compared to the CELL DCI-l state (because the transmitter and/or receiver may be switched off for longer periods of time while no uplink data is available and during discontinuous reception or "DRX") and also reduces the network signalling load (by avoiding radio resource control or "RRC" signalling to perform a state transition from the PCH or Idle states to the CELL FACH state when both data transmission and reception are required). Nevertheless, the CELL FACH state still has a higher power consumption for the user equipment than the PCH or Idle states.

For IJMTS, the 3GPP standards (sec 3GPP TS 25.331) allow the UE to trigger so-called Fast Dormancy by sending a SIGNALLING CONNECTION RELEASE INDICATION (SCM) in all connected states, including CELL PCH, URAPCH, CELL_FACH and CELL_DCH. In particular, if there is no more packet switched data that needs to be sent by the TiE, the TiE in one of the connected states can send the SCRI message with an information element (IE) "Signaling Connection Release Indication Cause" (SCRI with Cause) to the network/base station. As an alternative, this transition request may be sent in a "Cell Update" or a "URA Update" message.

S In any event, after the transition request message is received, the network may initiate a state transition, i.e. exchange control signals with the UE, to move the UE to Idle Mode, CELL PCH, URA PCH or CELL_FACH state to achieve lower power usage at the UE and reduced network signalling. For UMTS, the UE may trigger Fast Dormancy when in one of the paging channel states, i.e. the CELL_PCH state or the URAPCH state, as it wants the network to move it to the Idle Mode state to achieve maximum power savings and therefore typically longer battery life in the case of a mobile device. In the ease that the DRX cycle length in CELL_PCFI or URA_PCH as the case may be is equal to or longer than the DRX cycle length in Idle Mode, then the TiE is limited to sending the SCRI only once. However if the DRX cycle in CELL_PCH or URA PCH as the case may be is shorter than the DRX cycle length in Idle Mode, then the UE can send the SCRI as many times as it wants. The same issue may apply for other transition requests sent by the UE, including for example if the transition request is sent in a "Cell Update" or a "URA Update" message.

Similarly, for LTE, the 3GPP standards (see 3GPP TR 36.822) provide for the TiE to send assistance information to the eNB, to assist the eNB in configuring connected mode parameters and connection release handling for the UE. The UE can send to the eNB a 1-bit indication that it has a preference for a power-optimised configuration, which in the 3GPP specification is taken to indicate that for example a long DRX cycle or RRC connection release is desired.

Significantly, in each of these "Fast Dormancy" examples for UMTS and LTE, the UE remains attached to the network and, in particular, uses the same RAT before and after any change that was prompted by the network as a result of the network receiving the indication from the UE that the TiE wants to be moved to a state or configuration that consumes less power. Looking at this another way, the current Fast Dormancy proccdurcs of UIMTS and LTE considcr only thc RAT in which thc indication is sent. No account is taken of thc diffcrent powcr consumptions of states and/or usage behaviour that are available in different RATs.

S In broad terms, examples of embodiments of the present invention enable a liE to indicate to the network that it has a preference to move to a different RAT in order to achieve power savings. The UE may indicate a preference for being moved to a particular RAT spccificd by thc UE, and/or may indicate plural RATs to which it would likc to bc movcd in ordcr of prcfcrcncc.

As one example, LTE Idle mode may consume less power than a UMTS PCH state. As another example, a UMTS CELL_FACH state may consume less power than LTE Connected mode. Thcrc arc many othcr examples of possible diffcrcnt rates of powcr consumption bctwccn RATs for diffcrcnt UE statcs. Diffcrcnt ratcs of power consumption may result from different network configurations, including for example thc length of thc idle DRX pcriod, thc bandwidth, ctc. Such configuration settings are typically provided as System Information by the network.

Also, the relative rates of power consumption between RATs may differ according to thc particular application that is running on thc liE and consuming powcr, and/or thc particular usagc of thc application by thc uscr of thc UE at a particular time. For example, a TIE sending small amounts of data frequently may benefit from lower power consumption by being in one RAT, whereas another UE of the same type but with a different user (who has different usage behaviour) and/or applications in use may benefit from a lower power consumption by being in the other RAT because of the different usage of the liE by the user and/or applications running on that liE.

As a particular example, it may be advantageous in terms of minimising power consumption for the TIE to be moved to LTE for large data transfers, but remain in TiJVITS at all other times to conserve power. As yet another particular example, it may be advantageous in terms of minimising power consumption for the TiE to remain in LTE and move to UMTS only for CS (circuit switched) caHs or when the service may be degraded due to IDC (in-device coexistence) or other interference-avoidance measures that might be taken. Many other examples of different rates of power S consumption exist. The details of the actual power consumption depend on TiE implementations and network configurations, as well as the TiE type, the particular applications running on the UE and being used by the user, and user behaviour or usage of those applications or the liE in general.

In UMTS, one way for the TiE to indicate to the network that it would like to be moved to a different RAT to achieve powers savings is as follows. The TiE sends a SIGNALLING CONNECTION RELEASE INDICATION (SCRI) message to the network in which the message includes an indication that the UE wants to be moved to a different RAT and the message has a cause "power", or at least some indication that the "cause" or reason it wants to be moved is to obtain a power saving. The message from the liE to the network may specify a particular RAT to which the liE wants to be moved. Alternatively or additionally, the message from the TiE to the network may specil' a number of RATs to any of which the TiE wants to be moved, with the plural RATs being indicated in order of preference.

To illustrate this, as one particular example an indication may be added to "SIGNALLING CONNECTION RELEASE INDICATION" including one or both of the following: -single bit (where for example a 0' or a 1' indicates a preference for EUTRAN) -enumeration (using for example plural bits, for example to indicate a preference in order for EUTRAN, GERAN, UTRAN) and: -Cause (power) It will be understood however that the indication sent by the FE may be sent in some other way, such as in a different, separate indication or message altogether, typically in some uplink RRC signalling message. The preferred RAT indicated by the tiE may also be different from the specific example(s) given above.

S

For EUTRAN (LTE), the indication could be incorporated into an assistance information message, or may be sent in some other message, and may include similar information and options as detailed above for thc UNITS example.

In any event, the network will typically respond to receipt of such an indication or message by reconfiguring the TilE appropriately. For example, the network may redirect the LIE to another RAT, preferably the RAT or one of the RATs requested by the UE. Alternatively or additionally, the network may change the cell reseleetion priorities to be used by the FE such that the other RAT has a higher priority than before the message or indication was sent, increasing the likelihood that the UE will be moved to the desired RAT. Alternatively or additionally, the network may hand over the UE to a cell that uses another RAT, preferably the RAT or one of the RATs requested by the UE. Once the UE has been reconfigured by the network in this way, the TIE will typically move to the other RAT and/or cell, reconfiguring itself as necessary to use the appropriate transceiver, transmission frequency and protocol, etc. for the other RAT and/or cell.

A number of different criteria or mechanisms may be used by the UE to determine that it would like to be moved to a different RAT to achieve power savings.

The TIE may monitor actual power consumption over time for different network configurations, particular applications running on the tiE, different usage patterns by the user of the tiE, etc. Alternatively or additionally, the tiE may make an estimate of likely power usage. The estimate may be based at least in part on for example network configuration, including for example which features are enabled according to System Information provided by the network, such as length of the idle DRX period, the bandwidth, previous connected mode configurations in that RAT such as connected mode DRX lengths (for UMTSJLTE in an example), whether or not the network enaNes DRX in CELL FACH (for UMTS only in an examp'e), whether CPC (Continuous Packet Connectivity) is enabled (for UMTS in an example, this being another DRX feature for CELL_DCH), whether carrier aggregation has been S used (for UMTS/LTE in an example; this can determine whether one or two receivers need to be used by the TIE for example), etc., etc. Alternatively or additionally, the estimate may be based at least in part on for example the configuration of the TIE itself, such as which radios it may have enabled (bearing in mind that a UE might have separate radios for one or more of GPS, V/LAN, 2G!3G!4G, etc., etc.). Other factors for the configuration of the network and/or TIE may be taken into account.

The liE may "learn" based on previous activity which configurations a particular network is likely to use in different RATs, so the TIE may find one RAT more efficient than another for power saving. Also, the TIE may take into account which application or applications are running on the TIE (at a particular time) and hence which RAT has the best chance of conserving power when those applications are running. For example, a UE might prefer a network with the best data rate potential when using a streaming video service (e.g. YouTube or the like), but when changing to a messaging-like application (e.g. Skype or the like) typically requiring a lower data rate, the liE might prefer another RAT with a lower bit rate potential but a higher power saving potential. The UE might monitor average power consumption over time to learn how well the current network enables power saving and how each kind of network offers power saving opportunities on average. The TIE may record which applications are running at the relevant times so that it can make an informed decision as to which RAT is likely to be the most efficient in terms of power consumption at any particular time given the applications that are running on the liE at that time. The liE may record the different activity states at the relevant time so that it can make a better informed decision as to which RAT has the best chance of conserving power given the activity state of the TIE. For example, an LTE network might offer worse power consumption for speech calls when first deployed compared to a IJMTS network. The TIE may take into account that the network may command use of different transmission powers in different circumstances, for example to minimise interference (in-device interference TDC or interference with neighbouring liEs or other equipment), and that that may affect the rate of power consumption by the tiE. For example, the tiE might be using an LTE carrier which it knows to be S problematic for a Bluetooth headset currently in use, which might affect the LTE power consumption, so the UE might indicate to prefer a UMTS carrier which has no issue with the IDC interference.

Rules may be imposed on the UE to speci' when the UE is allowed and not allowed to send the indication that it would like to be moved to a different RAT. The TIE might need to be indicated via dedicated or broadcast signalling whether it is allowed to send such an indication. The rules for conditions in which such indication is allowed could also be predetermined according to radio conditions or other conditions perceived by the UE. The UE might also be always aflowed to send an initial indication but be prohibited from sending the indications afterwards until it receives a response or a predefined condition occurs, for example a timer expires.

The TIE might aLso be prevented from sending indications after having transferred from one RAT to another RAT via the preference indication, optionally for a predetermined period of time following the transfer. There may be different rules in different RATs concerning when the indication can be signalled.

Referring to Figure 2, there is shown a schematic flow diagram for an example of one embodiment of the present invention relating to the wireless device or UE. At 200, the wireless device operates using a first radio access technology under control of a network control apparatus. At 210, the wireless device determines that using a different radio access technology would consume less power. As a result, at 220, the wireless device signals to the network control apparatus that it would like to use the different radio access technology in order to achieve power savings.

Referring to Figure 3, there is shown a schematic flow diagram for an example of one embodiment of the present invention relating to the network or network control apparatus or the like. At 300, the network receives from a wireless device a request to use a different radio access technohgy in order to achieve power savings at the wireless device. At 310, the network transmits a signal that at least one of: (i) redirects the wireless device to the different radio access technology in response to S receipt by the network control apparatus of the signalling from the wireless device; (ii) changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority; and (iii) hands over the wireless device to a ccli that uses the different radio access technology.

Although at least some aspects of the embodiments described herein with reference to the drawings comprise computer processes performed in processing systems or processors, the invention also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice.

The program may be in the form of non-transitory source code, object code, a code intermediate source and object code such as in partially compiled form, or in any other non-transitory form suitable for use in the implementation of processes according to the invention. The carrier may be any entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a solid-state drive (SSD) or other semiconductor-based RAM; a ROM, for example a CD ROM or a semiconductor ROM; a magnetic recording medium, for example a floppy disk or hard disk; optical memory devices in general; etc. It will be understood that the processor or processing system or circuitry referred to herein may in practice be provided by a single chip or integrated circuit or plural chips or integrated circuits, optionally provided as a chipsct, an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), digital signal processor (DSP), etc. The chip or chips may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry, which are configurable so as to operate in accordance with the exemplary embodiments. In this regard, the exemplary embodiments may be implemented at least in part by computer software stored in (non-transitory) memory and exeeutaNe by the processor, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware).

S The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, the various indications that may be sent by the wireless device or TiE mentioned above may be sent in other forms. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments.

Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

CLAIMS1. A method of operating a wireless device under network control, the method comprising: S the wireless device operating using a fir st radio access technology under control of a network control apparatus; the wireless device determining that using a different radio access technology thc wireless device signalling to the network control apparatus that it would like to usc the different radio access technology in order to achieve power savings.
2. A method according to claim 1, the wireless device signalling to the network control apparatus plural different radio access technologies that it would like to use in order of preference in order to achieve power savings.
3. A method according to claim I or claim 2, the wireless device monitoring power consumption over time when using the first radio access technology and when using a different radio access technology so as to be able to determine that using the different radio access technology would consume less power.
4. A method according to claim 3, the wireless device monitoring power consumption over time for different applications running on the wireless device.
5. A method according to claim 3 or claim 4, the wireless device monitoring power consumption over time for different activity states of the wireless device.
6. A method according to any of claims 1 to 5, the wireless device estimating power consumption based on network configuration, or the wireless device configuration, or the network configuration and the wireless device configuration.
7. A method according to any of claims 1 to 6, wherein the first radio access technology is Universal Mobile Telecommunications System, the wirclcss device signalling to the network control apparatus that it would like to use the different radio access technology in order to achieve power savings by sending a SIGNALLING S CONNECTION RELEASE INDICATION message to the network control apparatus, the SIGNALLING CONNECTION RELEASE INDICATION message including an indication that the wireless device wants to use a different radio access technology and a cause indicat ive of power saving.
8. A mcthod according to claim 7, wherein thc different radio acccss technology is at least one of Long Term Evolution Evolved Universal Terrestrial Radio Access Network, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
9. A method according to any of claims I to 6, wherein the first radio access technology is Long Term Evolution Evolved Universal Terrestrial Radio Access Network and the different radio access technology is at least one of Universal Mobile Telecommunications System, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Acccss Network.
10. A method according to any of claims Ito 9, the wireless device receiving from the network control apparatus a signal redirecting the wireless device to use the different radio access technology in response to receipt by the network control apparatus of the signalling from the wireless device.
II. A method according to any of claims I to 10, the wireless device receiving from the network control apparatus a signal that changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority.
12. A method according to any of claims ito 11, the wireless device being handed over by the network control apparatus to a cell that uses the different radio access technology.S
13. Apparatus comprising a processing system for a wireless device, the processing system being constructed and arranged to: cause the wireless device to operate using a first radio access technology under control of a network control apparatus; determine if using a different radio access technology would consume less power; and cause the wireless device to signal to said network control apparatus that it would like to use the different radio access technology in order to achieve power savings.
14. Apparatus according to claim 13, arranged to cause the wireless device to signal to said network control apparatus plural different radio access technologies that it would like to use in order of preference in order to achieve power savings.
15. Apparatus according to claim 13 or claim 14, arranged to monitor power consumption by the wireless dcvicc over timc when using the first radio access technology and when using a different radio access technology so as to be able to determine that using the different radio access technology would consume less power.
16. Apparatus according to claim 15, arranged to monitor power consumption by the wireless device over time for different applications running on the wireless device.
17. Apparatus according to claim 15 or claim 16, arranged to monitor power consumption by the wireless device over time for different activity states of the wireless device.
18. Apparatus according to any of claims 13 to 17, arranged to estimate power consumption by the wirekss device based on network configuration, or the wireless device configuration, or the network configuration and the wireless device configuration.S
19. Apparatus according to any of claims 13 to 18, wherein the first radio access technology is Universal Mobile Telecommunications System, the processing system being arranged to cause the wireless device to signal to said network control apparatus that it would like to usc the different radio access technology in order to achieve power savings by sending a SIGNALLING CONNECTION RELEASE INDICATION message to said network control apparatus, the SIGNALLING CONNECTION RELEASE INDICATION message including an indication that the wireless device wants to use a different radio access technology and a cause indicative of power saving.
20. Apparatus according to claim 19, wherein the different radio access technology is at least one of Long Term Evolution Evolved Universal Terrestrial Radio Access Network, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
21. Apparatus according to any of claims 13 to 18, wherein the first radio access technology is Long Term Evolution Evolved Universal Terrestrial Radio Access Network and the different radio access technology is at least one of Universal Mobile Telecommunications System, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
22. A computer program for a wireless device, the computer program comprising instructions such that when the computer program is executed on a processing system of the wireless device, the wireless device is arranged to: operate using a first radio access technology under control of a network contr& apparatus; determine if using a different radio access technology would consume less power; and S signal to said network control apparatus that it would like to use the different radio access technology in order to achieve power savings.
23. A computer program according to claim 22, comprising instructions such that the wireless device signals to said network control apparatus plural different radio access technologies that it would like to use in order of preference in order to achieve power savings.
24. A computer program according to claim 22 or claim 23, comprising instruct-ions such that the wireless device monitors power consumption over time when using the first radio access technology and when using a different radio access technology so as to be able to determine that using the different radio access technology would consume less power.
25. A computer program according to claim 24, comprising instructions such that the wireless device monitors power consumption over time for different applications running on the wireless device.
26. A computer program according to claim 24 or claim 25, comprising instructions such that the wireless device monitors power consumption over time for different activity states of the wireless device.
27. A computer program according to any of claims 22 to 26, comprising instructions such that the wireless device estimates power consumption based on network configuration, or the wireless device configuration, or the network configuration and the wireless device configuration.
28. A computer program according to any of claims 22 to 27, wherein the first radio access technology is Universal Mobile T&eeommunieations System, the computer program comprising instructions such that the wireless device signals to said network control apparatus that it would like to use the different radio access S technology in order to achieve power savings by sending a SIGNALLING CONNECTION RELEASE INDICATION message to said network control apparatus, the SIGNALLING CONNECTION RELEASE INDICATION message including an indication that the wireless device wants to use a different radio access technology and a cause indicative of power saving.
29. A computer program according to claim 28, wherein the different radio access technology is at least one of Long Term Evolution Evolved Universal Terrestrial Radio Access Network, Global System for Mobile Communications Enhanced Data Rates for Global Evo'ution Radio Access Network, and Universal Terrestrial Radio Access Network.
30. A computer program according to any of claims 22 to 27, wherein the first radio access technology is Long Term Evolution Evolved Universal Terrestrial Radio Access Network and the different radio access technology is at least one of Universal Mobile Telceommunications System, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
31. A method of operating a network control apparatus, the method comprising: rcceiving, from a wireless device operating using a first radio access technology, a request to use a different radio access technology in order to achieve power savings at the wireless device; and in response thereto: transmitting a signal that at least one of: redirects the wireless device to the different radio access technology in response to receipt by the network control apparatus of the signalling from the wireless device; changes cell reselection priorities of the wireless device such that the different radio access technology has a higher priority; and hands over the wireless device to a cell that uses the different radio access technology.S
32. A method according to claim 31, wherein the first radio access technology is Universal Mobile Telecommunications System and the different radio access technology is at least one of Long Term Evolution Evolved Universal Terrestrial Radio Access Network, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
33. A method according to claim 31, wherein the first radio access technology is Long Term Evolution Evo'ved Universa' Terrestrial Radio Access Network and the different radio access technology is at least one of Universal Mobile Telecommunications System, Global System for Mobile Communications Enhanced Data Rates for Global Evolution Radio Access Network, and Universal Terrestrial Radio Access Network.
34. Apparatus comprising a processing system for a network control apparatus, the processing system being constructed and ananged to: upon receipt from a wireless device of a request to use a different radio access technology in order to achieve power savings at said wireless device, cause the network control apparatus to transmit a signal that at least one of: redirects said wireless device to use the different radio access technology; changes cell reselection priorities of said wireless device such that the different radio access technology has a higher priority; and hands over the wireless device to a cell that uses the different radio access technology.
35. A computer program for a network control apparatus, the computer program comprising instructions such that when the computer program is executed on a processing system of the network control apparatus, the network control apparatus is arranged to: upon receipt from a wireless device of a request to use a different radio access technology in order to achieve power savings at said wireless device, transmit a signal that at least one of: redirects said wireless device to use the different radio access technology; changcs cell reselection priorities of said wireless device such that the different radio access technology has a higher priority; and hands over the wireless device to a cell that uses the different radio access technology.
36. A method of operating a wireless device under network controL substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.
37. Apparatus for operating a wireless device, substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.