GB2541009A

GB2541009A - Power saving for cellular internet of things devices

Info

Publication number: GB2541009A
Application number: GB1513873.8A
Authority: GB
Inventors: Jun Wu Jian
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2015-08-05
Filing date: 2015-08-05
Publication date: 2017-02-08
Anticipated expiration: 2035-08-05
Also published as: KR102521218B1; GB2541009B; KR20170017757A; GB201513873D0

Abstract

A mobility indicator for power saving in a terminal device with limited mobility, such as a cellular internet of things device, is disclosed. A mobile communications network includes a base station configured to transmit data to and receive data from the terminal device when it is located within a geographical coverage area provided by the base station. A method comprises: receiving, from the base station, one or more signals identifying the base station; and transmitting, to the base station, registration information 502 for registering the terminal device, wherein the registration information includes a mobility indicator 508 indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station. The mobility indicator indicates the terminal device will be either stationary or moving within a boundary relative to the geographical coverage area provided by the base station. Registration information includes at least one of an indication of a volume of the user plane data 512, and an indication of the temporal frequency of the periodic transmission 510. The terminal device enters a reduced-power state for a predetermined period between the periodic transmissions of the volume of user plane data.

Description

Power Saving for Cellular Internet of Things Devices FIELD OF THE INVENTION

[0001] This invention relates to power saving for cellular Internet of Things (loT) devices. In particular, certain embodiments relate to power saving for cellular loT devices with limited mobility.

BACKGROUND OF THE INVENTION

[0002] Wireless or mobile (cellular) communications networks in which a mobile terminal (UE, such as a mobile handset, terminal device) communicates via a radio link to a network of base stations or other wireless access points connected to a telecommunications network, have undergone rapid development through a number of generations. The initial deployment of systems using analogue signalling has been superseded by Second Generation (2G) digital systems such as Global System for Mobile communications (GSM), which typically use a radio access technology known as GSM Enhanced Data rates for GSM Evolution Radio Access Network (GERAN), combined with an improved core network.

[0003] Data services of second generation systems have themselves been largely replaced by or augmented by Third Generation (3G) digital systems such as the Universal Mobile Telecommunications System (UMTS), which uses a Universal Terrestrial Radio Access Network (UTRAN) radio access technology and a similar core network to GSM. UMTS is specified in standards produced by 3GPP. Third generation standards provide for a greater throughput of data than is provided by second generation systems. This trend is continued with the move towards Fourth Generation (4G) systems and Fifth Generation (5G) systems.

[0004] 3GPP design, specify and standardise technologies for mobile wireless communications networks. Specifically, 3GPP produces a series of Technical Reports (TR) and Technical Specifications (TS) that define 3GPP technologies. The focus of 3GPP is currently the specification of standards beyond 3G, and in particular on standard for the Evolved Packet Core and the enhanced radio access network called “E-UTRAN”. The E-UTRAN uses the LTE radio technology, which offers potentially greater capacity and additional features compared with previous standards. Despite LTE strictly referring only to the air interface, LTE is commonly used to refer to the whole system including EPC and E-UTRAN. LTE is used in this sense in the remainder of this specification, including when referring to LTE enhancements, such as LTE Advanced. LTE is an evolution of UMTS and shares certain high level components and protocols with UMTS. LTE

Advanced offers still higher data rates compared to LTE and is defined by 3GPP standards releases from 3GPP Release 10 up to and including 3GPP Release 12. LTE Advanced is considered to be a 4G mobile communication system by the International Telecommunication Union (ITU).

[0005] It is anticipated that 5G mobile communications systems will be rolled-out in the future. Currently, the network structure and wireless access interface to be used in 5G systems has not been decided upon. However, in order to reduce deployment costs and integrate with 4G systems, it is envisaged that 5G systems may utilise some of network architecture currently used in 4G systems.

[0006] Consequently, although particular embodiments of the present invention may be implemented within an LTE mobile network, they are not so limited and may be considered to be applicable to many types of wireless communication networks, including future 5G systems. However, due to the greater certainty surrounding the structure of systems based upon LTE network, embodiments of the present invention will predominantly be described with reference to the structure and network elements of LTE based systems. Consequently, an example LTE system is shown in Figure 1.

[0007] The LTE system of Figure 1 comprises three high level components: at least one UE 102, the E-UTRAN 104 and the EPC 106. The EPC 106, or core network as it may also be known, communicates with Packet Data Networks (PDNs) and servers 108 in the outside world, such as those which form the Internet for example. Figure 1 shows the key component parts of the EPC 106. It will be appreciated that Figure 1 is a simplification and a typical implementation of LTE will include further components. In Figure 1 interfaces between different parts of the LTE system are shown. The double ended arrow indicates the air interface between the UE 102 and the E-UTRAN 104. For the remaining interfaces user data is represented by solid lines and signalling is represented by dashed lines.

[0008] The E-UTRAN 104, or radio access network (RAN) as it may also be known, comprises a single type of component: an eNB (E-UTRAN Node B) which is responsible for handling radio communications between the UE 102 and the EPC 106 across the air or wireless access interface. An eNB controls UEs 102 in one or more cell. LTE is a cellular system in which the eNBs provide coverage over one or more cells where the cells correspond to a geographical coverage area. Typically there is a plurality of eNBs within an LTE system. In general, a UE operating in accordance with LTE communicates with one eNB through one cell at a time, where an eNB may also be referred to as a base station or mobile base station.

[0009] Key components of the EPC 106 are shown in Figure 1. It will be appreciated that in an LTE network there may be more than one of each component according to the number of UEs 102, the geographical area of the network and the volume of data to be transported across the network. Data traffic is passed between each eNB and a corresponding Serving Gateway (S-GW) 110 which routes data between the eNB and a PDN Gateway (P-GW) 112. The P-GW 112 is responsible for connecting a UE to one or more servers or PDNs 108 in the outside world. The Mobility Management Entity (MME) 114 controls the high-level operation of the UE 102 through signalling messages exchanged with the UE 102 through the E-UTRAN 104. Each UE is registered with a single MME. There is no direct signalling pathway between the MME 114 and the UE 102 (communication with the UE 102 being across the air interface via the E-UTRAN 104). Signalling messages between the MME 114 and the UE 102 comprise EPS Session Management (ESM) protocol messages controlling the flow of data from the UE to the outside world and EPS Mobility Management (EMM) protocol messages controlling the rerouting of signalling and data flows when the UE 102 moves between eNBs within the E-UTRAN. The MME 114 exchanges signalling traffic with the S-GW 110 to assist with routing data traffic. The MME 114 also communicates with a Home Subscriber Server (HSS) 116 which stores information about users registered with the network.

[0010] In additional to the architectural structure discussed above, LTE also includes the concept of bearers, and in particular, EPS bearers, where data transmitted from and received by a UE is associated with a particular bearer. EPS bearers themselves may be formed from an e-Radio Access Bearer (e-RAB) which extends between the UE and EPC and S5/S8 Bearers which extend within the EPC. EPS bearers define how UE data is handled as it passes through the LTE network and may be viewed as a virtual data pipe extending through the core network, where a bearer may have quality of service associated with it, such as a guaranteed bitrate for example. A bearer serves to channel packet data to a Packet Data Network (PDN, also referred to as a Public Data Network) outside of the LTE network via the S-GW and P-GW, where a further external non-LTE bearer may be required to channel data from the EPC to an external network. Each bearer is therefore associated with a certain PDN and all data associated with the bearer passes through a particular P-GW. Each bearer is also identified by a Logical Channel ID (LCID) at the Medium Access Control (MAC) level, where one bearer corresponds to one logical channel.

[0011] Recently there has been increased interest in the concept of the Internet of Things (loT), where a large number of conventionally unconnected devices are provided with means to connect to and communicate with one another and/or communications networks in order to exchange information and perform the control of objects and processes. Examples of devices which may form an loT include smart utility meters, washing machines, dishwashers, thermostats, home security devices, automobile sensors, health related sensors and so forth.

[0012] The ‘things’ or devices of the loT may communicate by any suitable wireless communication technique or standard, however, it is anticipated that devices may use cellular networks such that a Cellular loT (CloT) is formed. More specifically, it is currently anticipated that 3GPP networks such as those based on LTE and LTE Advanced will be used in the near future due to their relatively extensive geographical coverage, ability to service a large number of devices and the scope for low-power operation of LTE devices. However, the loT or CloT is not limited to the use of such networks and may use any suitable communications network. Throughout this disclosure, both loT devices and CloT devices are referred to, however, the techniques disclosed herein are not limited to only one of these types of devices and may be implemented on any user equipment or terminal device, such a smart phone, tablet computer for example.

[0013] In a number of the example loT devices set out above, it may not be practical or cost efficient to provide a mains power connection or a means to recharge/change batteries. Furthermore, current expectation is that the battery lifespan of loT devices should be 10 years or more such that devices and/or batteries do not require frequent replacement.

[0014] Accordingly, there is need to reduce the power consumption of loT devices. With regard to CloT devices, their communication via cellular networks may represent a significant portion of their battery usage and therefore reducing the power consumed by cellular communications at a CloT device may be important in achieving the 10 or more years battery life currently expected. Consequently, reducing the power consumption of CloT devices communications presents a technical problem to be solved.

BRIEF SUMMARY OF THE DISCLOSURE

[0015] In accordance with a first aspect of the present invention, a method of operating a terminal device for receiving data from and transmitting data to a mobile communications network is provided. The mobile communications network includes a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, and the method comprises receiving, from the base station, one or more signals identifying the base station; and transmitting, to the base station, registration information for registering the terminal device with the mobile communications network, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

[0016] In certain embodiments the mobility indicator may provide an indication that the terminal device has limited mobility.

[0017] In certain embodiments, the mobility indicator indicates the terminal device will be either stationary or moving within a boundary relative to the geographical coverage area provided by the base station. By virtue of providing an indication that a terminal device has limited mobility and is thus unlikely to move between base station coverages area, the network may reduce the level of mobility management signalling required to be performed by the terminal device. Furthermore, the network may also allow the device to enter a reduced power state for extended periods of time without requiring it to re-register with the network upon resumption of communications with the network since its registration details are unlikely to have changed.

[0018] In certain embodiments the method further comprises periodically transmitting a volume of user plane data to the base station, and the registration information includes at least one of an indication of the volume of the user plane data, and an indication of the temporal frequency of the periodic transmission [0019] In certain embodiments the method further comprises entering a reduced-power state at the terminal device for a predetermined period between the periodic transmissions of the volume of user plane data.

[0020] In certain embodiments the method further comprises receiving, from the base station, an indication of an uplink resource allocation in which to transmit the volume of user plane data; and entering a reduced-power state at the terminal device for a predetermined period prior to the indicated uplink resource allocation.

[0021] In certain embodiments the reduced-power mode may be referred to as a network disconnected mode during an on state, during which the terminal device does not communicate with the network such that its receiver and or transmitter may be powered-down. Subsequently, when the terminal devices transitions to a network disconnected mode off state and resumes communications with the network, the terminal devices is required to perform reduced signalling compared to a terminal device first registering with a network or a terminal device exiting a discontinuous reception cycle.

[0022] In certain embodiments the method further comprises receiving, from the base station, an indication of the predetermined period.

[0023] In certain embodiments the indication of the predetermined period includes a timer value, and the method further comprises initiating a timer with the timer value in response to entering the reduced-power state, and exiting the reduced-power state in response to expiry of the timer.

[0024] In certain embodiments transmitting the volume of user plane data to the base includes transmitting the volume of user plane data in a random access channel.

[0025] In accordance with another aspect of the present invention, a method of operating a mobile communications network for transmitting data to and receiving data from a terminal device is provided. The mobile communications network includes a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, and the method comprises transmitting, to the terminal device, one or more signals identifying the base station; receiving, from the terminal device, registration information for registering the terminal device with the mobile communications network; and registering the terminal device with the mobile communications network based upon the registration information, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

[0026] In certain embodiments the mobility indicator may provide an indication that the terminal device has limited mobility.

[0027] In certain embodiments the mobility indicator indicates the terminal device will be either stationary or moving within a boundary relative to the geographical coverage area provided by the base station.

[0028] In certain embodiments the method further comprises periodically receiving a volume of user plane data from the terminal device, and the registration information includes at least one of an indication of the volume of the user plane data, and an indication of the temporal frequency of the periodic transmission.

[0029] In certain embodiments the method further comprises determining an allocation of uplink resources in which to receive volume of user plane data based on one or more of the indication of the volume of the user plane data and the indication of the temporal frequency of the periodic transmission; and transmitting, to the terminal device, an indication of the determined uplink resource allocation.

[0030] In certain embodiments the terminal device is configured to enter a reduced-power state for a predetermined period prior to the indicated uplink resource allocation, and the method further comprises determining the predetermined period based on the indication of the temporal frequency of the periodic transmission; and transmitting, to the terminal device, an indication of the predetermined period.

[0031] In certain embodiments the mobile communications network is configured to transmit a location update request to terminal devices registered with the mobile communications network, and the method further comprises suspending, in response to receiving the mobility indicator, the transmission of location update requests to the terminal device.

[0032] In certain embodiments the registering includes generating connection context information for the terminal device, and the method further comprises maintaining the connection context information between the periodic reception of the volume of user plane data.

[0033] In accordance with another aspect of the present invention, a mobile communications network for transmitting data to and receiving data from a terminal device is provided. The mobile communications network includes a core network and a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, wherein the base station is configured to transmit, to the terminal device, one or more signals identifying the base station; and receive, from the terminal device, registration information for registering the terminal device with the mobile communications network; and the core network is configured to register the terminal device with the mobile communications network based upon the registration information, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

[0034] In accordance with another aspect of the present invention, a terminal device for receiving data from and transmitting data to a mobile communications network is provided. The mobile communications network includes a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, wherein the terminal device comprises a receiver configured to receive, from the base station, one or more signals identifying the base station; and a transmitter configured to transmit, to the base station, registration information for registering the terminal device with the mobile communications network, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 provides a schematic illustration of an LTE mobile communication network;

Figure 2 provides a schematic illustration of a Cooperative Ultra-Narrow Band (C-UNB) communications network;

Figure 3 provides a schematic illustration of a Cooperative Ultra-Narrow Band (C-UNB) communications network;

Figure 4 provides a schematic illustration of the mobility management procedures in a 3GPP communication network;

Figure 5 provides a flow diagram of a Network Disconnected Mode (NWDM) setup procedure in accordance with an embodiment of the present invention;

Figure 6 provides a schematic illustration of mobility management procedures in accordance with an embodiment of the present invention; and

Figure 7 provides a flow diagram of a Network Disconnected Mode (NWDM) state transition procedure in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

[0036] In 3GPP networks such as those based on LTE and LTE Advanced, terminal devices include two broad modes of operation: Radio Resource Control (RRCJdle) idle mode and RRC connected mode (RRC_Connected). In the RRCJdle mode a device is not currently communicating user plane data with the network but is regularly monitoring a paging channel such that the device can be alerted by the network if there is downlink data to be transmitted. Consequently, in RRCJdle mode no Non-Access Stratum (NAS) signalling exists between the device and the core network, but a PDN connection exists, the device is registered at the MME and the location of the device is known to the MME though the performance of tracking area updates. In contrast, in RRC_Connected mode the device is allocated resources in either the uplink or downlink and is transmitting/receiving or expecting to transmit/receive data in the allocated resources.

Even though the signalling performed by device in RRCJdle mode is reduced compared to the RRC_Connected mode, given the number and regularity of various procedures which are required to be performed in RRCJdle mode it is unlikely that the desired 10 year battery life desired for CloT devices will be met using only these two operational modes.

[0037] Accordingly, there are a number of approaches for reducing the power consumption of devices in 3GPP networks have been proposed, two of these are discontinuous reception (DRX) or extended RX (eDRX), and cooperative ultra-narrow band (C-UNB).

Discontinuous Reception (DRX) [0038] Discontinuous reception (DRX) is a technique for reducing power consumption at devices by reducing the time that a device’s receiver is operational. As set out above, in RRCJdle mode a device is required to monitor a paging channel in order that the device can be contacted by the network, however, monitoring the paging channel continuously is a power intensive activity since it may require receiving signalling in one or channels in each subframe of the wireless access interface provided by the mobile communications network and thus requires a receiver to be active for a substantially period of time. Consequently, the concept of DRX was proposed. In DRX, instead of monitoring the paging channel or other physical control channel of every frame or subframe, a device is configured via negotiations with the network to enter a DRX cycle of a particular length, where the device is configured to monitor a paging or downlink control channel only in an active period of the DRX cycle, and the network is configured to only signal to the UE during the active period of the DRX cycle. By virtue of this, the frequency at which the devices monitors for networks signalling is reduced. For example, a device may be configured to monitor the paging channel only once per 10 radio frames and enter a sleeplike state (non-active) where the LTE receiver is powered down in between these monitoring instance in order to reduce power consumption. If the network obtains data which is intended for the device, the network waits until the next DRX active period of the device and transmits a paging message to the device, signalling that the device should exit DRX and transition to RRC_Connected in order to receive the downlink data.

[0039] In order or to further reduce power consumption, and in particular for Machine Type Communications (MTC) devices, it has been proposed in 3GPP TR 45.820 v1.4.0 to introduce an extended DRX mode (eDRX) where the period of the DRX cycle is significantly increased. Table 1 below shows proposed eDRX cycles where the cycle lengths has a current maximum value of 52 minutes such that a device will check the paging channel or other specified channel approximately every 52 minutes. The desired eDRX cycle is indicated using the four bit EXTENDEDJDRX codes, where additional codes not included in the Table 1 may be used for eDRX cycles having a length which are not included in Table 1.

Table 1

Cooperative Ultra Narrow Band (C-UNB) [0040] An alternative method to reduce the power consumption of devices, and CloT devices in particular, is termed Cooperative Ultra-Narrow Band (C-UNB) radio access technology (RAT). In such an approach devices are not required to be synchronized or attached to network or base station before being allowed to send packets to the network and thus the control signalling required to be monitored and transmitted by a device is reduced. Instead, network access is based on random transmissions by devices. This kind of medium access is equivalent to ALOHA, which is known for its simplicity. However, its simplicity is also its drawback since packet collisions that hamper the overall efficiency when the network load becomes high are likely. To overcome this issue, the C-UNB RAT implements two mitigation techniques: frequency diversity and spatial diversity.

[0041] Figure 2 provides a schematic illustration of a C-UNB architecture where additional software and server(s) may be required to implement C-UNB since it does not use existing elements of a 3GPP core network. For example, in addition to the base stations 202, 204 206, the base station controllers (BSC) and packet control units (PCU) 208,210, the Serving HPRS Support Node (SGSN 212), and Gateway GPRS Support Node (GGSN) 214, additional software to handle C-UNB communications is required at the base stations and a C-UNB server 216 is required in the core network to collate the various reception instances of data resulting from the spatial and/or frequency diversity.

[0042] In additional to the use of an alternative network structure, in order to provide the spatial diversity, it is required that base station coverage areas overlap with one another since the radio access network should receive multiple copies of the same radio packet with different base stations. Figure 3 provides a schematic illustrations of the use of multiple base stations in order to achieve spatial diversity. More specifically, device 302 transmits a packet which is received at base stations A and C 306, 310 and the two reception instances are combined at the C-UNB server in order to take advantage of the spatial diversity. Likewise, device 304 also transmits packets to base stations A and C 306, 310 and the two receptions instances are combined and de-duplicated at the C-UNB server 312 in order to take advantage of the spatial diversity. In addition to the added complexity resulting from the adapted network structure required to take advantage of the spatial diversity, due to access technique of C-UNB there is there is no acknowledgment of uplink data packets, thus potentially leading to the unreliable transmission of data to the core network. Furthermore, there is no facility for the transmission of data in the downlink to the devices using only C-UNB.

[0043] Although the use of eDRX and C-UNB may lead to reductions in power consumption at CloT devices, there are a number of disadvantages and shortcomings of such techniques that render them unlikely to be able to achieve the power savings required if a battery life exceeding 10 years is to be achieved. For example, with regard to eDRX, the maximum possible cycle lengths may not be sufficient for devices which only wish to report data every week. Likewise, DRX merely reduces the frequency of certain procedures such as paging for example but does not fundamentally change the processes performed by a device. For example, even though eDRX may reduce the frequency at which a paging channel is checked, a number of other procedures at the device are still required to be performed, such as the mobility management procedures for example.

[0044] Figure 4 provides a diagram illustrating the mobility management protocol as set out in the 3GPP technical specification TS24.008. Although describing the full mobility management protocol in detail is beyond the scope of the present disclosure, the complexity of the protocol and the number of independent task that are required to be performed is evident from Figure 4. Furthermore, some of the procedures of illustrated may not be required after initial registration of a device since it the resulting information may not change. For example, if a device does not change location, it may not be necessary to perform regular location updates.

[0045] Consequently, in order to reduce resources consumed by mobility management of low mobility devices, in 3GPP TS 22.368, a Machine Type Communication (MTC) low mobility feature as well as a high mobility feature were defined, where low mobility is defined as less than 30km per hour maximum speed and high mobility as larger than 30km per our maximum speed in TR 45.820 v1.4.0. The MTC Feature Low Mobility is intended for use with MTC Devices that do not move, move infrequently, or move only within a certain region and includes the ability for a network operator to change the frequency of mobility management procedures or simplify mobility management per MTC Device, and to define the frequency of location updates performed by the MTC Device in order to reduce signalling overheads and reduce power consumption at a user devices.

[0046] However, in an analogous manner to eDRX and the checking of a paging or control channel, the Low Mobility feature only allows changing the frequency of mobility management procedures and location updates but it does not allow for the removal of mobility management completely for Low Mobility MTC devices. Consequently, even with the use of this approach, potentially unnecessary mobility management procedures may consume radio resources and reduce battery life of CloT devices even though they may not move or move only within a smart home and thus their mobility information does not require updating.

Limited Mobility Internet of Things Devices [0047] As set out above, in current mobile networks such as those based upon the 3GPP standards, mobility management is based on the assumption that devices connected to the network are mobile to some extent and thus can be classed as those with low mobility and high mobility (high and low speed). However, such classification does not take into account devices which are predominantly stationary and are unlikely to move between cells i.e. the geographical coverage area of the base station with which they are current connected to the mobile network via. Accordingly, the mobility management features of 3GPP networks are also not adapted for efficient use with predominantly or substantially stationary devices such as CloT device in a smart home, which do not or are not expected to move out with respect to coverage area of the base station to which they are currently connected. Consequently, in accordance with an embodiment of the present invention, a new limited mobility class of device is defined such that when first registering with a network, a CloT device (or potentially any other device) may indicate to the network that it has limited mobility as an alternative to low or high mobility and thus indicate to the network that its location with respect to the current cell (base station geographical coverage area) may not change or may only change relatively infrequently, or in other words is stationary or moving within the same cell i.e. substantially stationary relative to the coverage area of its current base station or does not change cells between communication instance with the network. By virtue of defining such a mobility indicator, the device and network may adapt various procedures, such as the mobility management, in order to take account of the stationary nature of the device, reduce potentially unnecessary overheads, and thus reduce power consumption at the device.

[0048] When a device is first turned-on and registers with a mobile network, it may indicate various parameters to the network via the transmission of a registration information that may include a classmark, which, among other things, may include an indication of the expected mobility of the device i.e. less than or greater than 30km per hour in current 3GPP technical specifications for example so that mobility management procedures can be adapted accordingly. However, in accordance with the present invention, an additional mobility class is provided for in the classmark that enables a device to indicate that it has limited mobility and thus is substantially stationary on a cell-wise basis with respect to time. For example, the classmark single may include the following bits as shown in Table 2 below to indicate the mobility class of the device.

Table 2 [0049] In contrast to the existing low and high mobility indicators, the limited mobility indicator provides an indication of mobility with respect to cells, cell boundaries and base station coverage areas rather than the speed of the device, thus the mobile network is provided with alternative information specifying whether the device is likely to move cells. This therefore allows for the scenario where a terminal device such as CloT device may move around a home for example at any speed but does not change cells and also for a device which is substantially stationary with respect to movement speed.

[0050] As is explained in more detail below, with this additional mobility information the network may simplify mobility management procedures and paging procedures since it can be assumed that the device is unlikely to change cells.

[0051] In addition to defining a new mobility class, in accordance with embodiments of the present invention, a new operational mode (in addition to RRCJdle and RRC_Connected) is also defined for devices with limited mobility, where this mode may be referred to as Network Disconnected Mode (NWDM). As is explained below in more detail, NWDM may viewed as a mode between RRCJdle and a device not currently registered with a network. It is anticipated that such a mode will be primarily of use to devices which are required to communicate with a network relatively infrequently, such as CloT devices for example, though in practice any device may make use of such a mode.

[0052] The NWDM and hence a terminal device may either be in On (NWDM-On state) or Off (NWDM-Off state), where during the NWDM-On state a device may shut down the relevant receiver and not communicate with the network. Conversely, when in the NWDM-Off state the device may communicate with the network to transmit and receive data. Transitions between the NWDM-On and NWDM-Off states may be coordinated with the network such that the network does not attempt to communicate with a device when it is in the NWDM-On state. Subsequently, when a device transitions to the NWDM-Off state, the relevant receiver is powered-on and communications initiated with the network. As is explained in more detail below, when a device of limited mobility transitions between from the NWDM-On state to the NWDM-Off state, it is required to perform fewer signalling procedures with the network compared to a device which transitions from DRX to RRC_Connected in order to transmit and receive data, since, for example, location updates may not be required, and thus power consumption at the device may be reduced compared to DRX. Furthermore, as is also explained in more detail below, when a device is in the NWDM-Off state, although it is effectively disconnected from the network, the core network maintains the connection context of the device (PDN connection, IP address etc.) and the device’s registration and thus when reconnecting to the network, the device is not required to be perform a number of procedures which a conventional device being powered-on would be required to perform.

[0053] When a device transitions from the NWDM-On state and NWDM-Off state, the communications between the device and the network may take a number of alternative forms. In a first example, the device may have been pre-allocated uplink resources in a particular frame where this allocation was performed and indicated to the device prior to the device entering NWDM-On state, and the network has knowledge when the device is scheduled to transition between the NWDM-On and the NWDM-Off states. Consequently, when the device enters the NWDM-Off state, it transmits data to the network in the preallocated resources and the network receives the data.

[0054] In a second example, the device may have been pre-allocated downlink resources in a particular frame where this allocation was performed and indicated to the device prior to the device entering the NWDM-On state and the network has knowledge when the device is scheduled to transition between the NWDM-On and NWDM-Off states. Consequently, when the device enters the NWDM-Off state, it receives data from the network in the pre-allocated resources.

[0055] In a third example, the instead of transmitting or receiving data directly to/from the network upon transitioning to the NWDM-Off state, the device first receives an indication of downlink or uplink resources that it has been allocated and then proceeds to transmit or receive data, where the device may be required to receive signalling from a broadcast channel or other forms of control channel upon transitioning to the NWDM-Off state in order to obtain an indication of the allocated resources. Although such an approach may be more resource intensive due to possible increase in signalling, this approach enables the resources allocations to be determined close to the use of the resources, thus allowing for more flexible resource allocation.

[0056] In a fourth example, if a device has a relatively small volume of data to transmit in the uplink, as may be case for a utility smart meter for example, the uplink data may be transmitted in a random access channel such as the Physical Random Access Channel (PRACH) of a 3GPP wireless access interface, thus overcoming the need to allocate dedicated resources to the device and reducing overheads further since resource allocation signalling may not be required either preceding and subsequent to transitioning from the NWDM-On to NWDM-Off states.

[0057] The use of the NWDM may entail a device entering a sleep-type state or reduced-power state (NWDM-On state), during which the receiver may be turned-off for example, and periodically waking to communicate with the network (NWDM-Off state). For example, a utility smart meter may be required to report to a network every day or week.

Furthermore, due to the nature of many loT devices, their data usage patterns may be relatively predictable or and periodic and the volume of data transmitted at each communication event relatively constant, for example, a utility smart meter may only transmit data representing a 5 digit meter reading and associated error coding.

[0058] Consequently, for the NWDM to be effectively configured by the network and for resources to be allocated efficiently or pre-allocated, it would be advantageous if information on or an indication of data transmission frequency and resource usage of a device is provided to the network prior to entering the NWDM.

[0059] Therefore, in accordance with embodiments of the present invention, in addition to providing a mobility indication as part of registration information to the network when first registering with the network, if a device indicates that it is limited mobility, the device may also provide a data transmission frequency indicator and/or a resource usage indicator which indicate to the network the expected data transmission frequency and/or resource usage (data volume transmission) of a device.

[0060] A data transmission frequency indicator may indicate a particular frequency transmission class or period, where the classes may represent temporal transmission frequencies of every minute, hourly, daily or weekly for example. Such an indicator may be transmitted along with the limited mobility indicator in the classmark (registration information) or may be transmitted subsequent to the classmark or other registration information. In some examples, the data transmission frequency may be transmitted when requested by the network.

[0061] Table 3 below provides a number of example codes that may be transmitted as part of the classmark to indicate the data transmission frequency class which a CloT device belongs to, where codes made up of fewer or a greater number of bits may also be used and the time periods may also vary.

Table 3 [0062] Once an indicator of the data transmission frequency has been provided to the network, if resources are to be pre-allocated to device for when it transitions to the NWDM-Off state, the network may allocate such resources and indicate a timer value to the device that will expire close to when the pre-allocated resources occur. Consequently, the device and the network may have substantially synchronised timer set to the appropriate period, whereby when the device enters the NWDM-On state the timer is started and the device transitions to the NWDM-Off state when the timer expires. Likewise, the core network may also include a corresponding timer such that it is provided by with an indication of when a device is to transition from the NWDM-On state to the NWDM-Off state.

[0063] Although Table 3 and the foregoing description predominantly refers to frequency transmission indicators in terms of time, and it is specified that timers may be used at the device and network to coordinate the transitions between NWDM states, the present invention is not limited to such implementations. For instance, instead of a temporal indicator, alternative decision parameter(s) may be set as the trigger for transitioning between NWDM states. For example, a change in an environmental parameter such as weather conditions and alarm messages may trigger a NWDM state transition.

Alternatively, a change in frequency parameters of a network may be used at the device and network to initiate the transition between NWDM states. Although preferably both the device and the network will have knowledge of the decision parameter and the condition related to the decision parameter such that the device and network can be approximately synchronised, this may not always be the case. For example, with regards to a decision parameter based on environmental conditions of which the network does not have knowledge, the device may transition between the NWDM states based on the a change of environmental conditions and the decision parameter and then subsequently inform the network of such a transition. In such an example, the network may maintain the connection context of the device but not allocated resources or provide any signalling for the device until the device has indicated to the network that it has transitioned to the NWDM-Off state.

[0064] A resource usage indicator i.e. a data volume indicator may indicate a particular resource usage class where each class corresponds to an expected volume of user plane data that a device expects to transmit and or receive when it enters the NWDM-Off state. By virtue of the provision of such an indicator, the network may accurately and efficiently pre-allocate resources to the device, such that the device may be provided with an indication of the resources prior to entering the NWDM-On state and powering-down the relevant receiver and/or transmitter.

[0065] As for the data transmission frequency indicator, a number of different classes may be defined based on the volume of data which is to be transmitted, for example, as shown in Table 4 below, four different classes may be defined. Although only four classes are shown in Table 4, any number of classes may be defined each with a different associated data volume.

Table 4 [0066] In addition to providing relatively exact data transmission volumes indicators, as shown by the code 11 in Table 4, an indicator may also be provided which indicates that the data requirements of the device may vary, therefore resources requirements may be required to be negotiated prior to each transmission rather than in advance prior to the device entering the NWDM-On state. As for the data transmission frequency indicator, the data volume indicator may be transmitted along with the limited mobility indicator in the classmark, transmitted subsequent to the classmark and transmitted in response to a request from the network.

[0067] By virtue of providing the network with a data transmission frequency indicator and a data volume indicator, the network can set up the NWDM with the device by setting an appropriate timer (or other decision parameter) and allocating an appropriate volume of resources, and indicate these parameters to the device. In response, the device may initiate a substantially synchronised timer and record the resource allocation, and enter and remain in the NWDM-On state until the expiry of the timer. Upon expire of the timer, the device may then transition to the NWDM-Off mode and utilise the allocated resources. The allocated resources may be a one-time allocation such that a different allocation is provided to a device prior to each entry into the NWDM-On state, or may be a persistent allocation where a device is provided with a same allocation of resources for each time it enters the NWDM-Off state. Although the use of a persistent resource allocation may reduce flexibility in resource allocation, it may results in reduced signalling overheads since an allocation may only be required to be signalled to the device once.

Device Registration and Network Disconnected Mode Setup [0068] Figure 5 provides a flow diagram illustrating an example procedure for setting up the NWDM at a CloT device in accordance with an example of the present invention.

[0069] At Step 502, the CloT device registers with the network according to any suitable approach as set out in the 3GPP standards. For example, the base station may transmit one or more signals identifying the base station and/or providing information required for the device to register with the network. The process of registration is envisaged to occur when a device is first turned-on, however, it may also occur for example if synchronisation in terms of NWDM transitions between the network and the device is lost or the device moves between coverages areas and thus attaches to an alternative base station.

[0070] At Step 504, the device determines whether it is a CloT device with limited mobility, i.e. whether it stationary or stationary relative to the current base station coverage area and therefore does not expect to change cells/base stations. A CloT device may be pre-configured with such information, or alternatively it may be user configurable or a device may determine its mobility itself be monitoring the available cells whose coverage area it is within.

[0071] At Step 506, if the device is not of limited mobility the device may perform conventional 3GPP procedures for mobility management, resource allocation and the like by virtue of not including a limited mobility indication in registration information.

[0072] At Step 508, if it is determined that the device is of limited mobility, the device transmits such an indication to the network. For example the device may include the indication in a classmark signal which is transmitted to the network. By providing such an indication to the network, the network may adapt it registration procedure to take account of the limited mobility of the registering device.

[0073] At Step 510 the device transmits a transmission data frequency class indicator or other decision parameter to the network.

[0074] At step 512, the device transmits a resource usage class to the network and may also optionally transmits at Step 513 a clock/timing accuracy class or indication to the network which, as is explained below, may be used by the network to determine a NWDM a timer value.

[0075] Although Steps 508, 510, 512 and 513 have been illustrated as being separate, they may also be included in a single transmission or provided upon request by the network. For example, the various indicators may all be included in the classmark signal which is transmitted once it has been determined that the device has limited mobility. Furthermore, as shown in Tables 2 to 4, the various indicators may be formed from relatively few bits and therefore these bits may be included in a current classmark by using currently unused bits in the classmark signal as defined in 3GPP technical specifications.

[0076] At Step 514, the device receives NWDM parameters from the network which has determined them based upon the data transmission class indicator and resource usage class indicator. The device then configures the NWDM mode by initiating and starting a timer, and where appropriate recording any pre-allocated resources. It is also at this point that the connection parameters of the device may be configured by the network and device. For example, one or more of authentication, identification, context establishment, PDN connection(s) establishment, IP address allocation may also be performed at Step 514. In order to generate the NWDM setup parameters, the network may perform a number of determination steps at Step 514, for example, the network may determine the resource allocation based on the data resource and data transmission frequency indicators and determine a timer value based on the data transmission frequency period and/or the determined resource allocation. The network may also provide other information to the device, for example a synchronisation indicator in order for the timer to be synchronised.

[0077] At Step 516, once the NWDM has been set up, the device determines whether it is either in the NWWDM-On or NWDM-Off state i.e. by checking for the expiry of a timer for example. If the device is in the NWDM-On state the device disconnects from the network at Step 516 and does not transmit or receive data from the network. In an alternative implementation, the terminal may enter the NWDM-On state once it has transmitted its data and then start the timer such that the initiation of the timer is in response to entering the NWDM-On state. Alternatively, if the network disconnected mode timer is not running, the device connects to the network at Step 518 and commences the transmission and/or reception of data according to the connection parameters set up during Step 514.

[0078] The setting up of the NWDM may include a number of further steps or alternative steps which are not illustrated in Figure 5. For example, upon the provision of the data transmission frequency indicator and resource usage indicator to the network, the network may determine an absolute time at which the device should exit the NWDM-On state and communication this to the device rather than providing a timer values. The network may also not determine the NWDM state transition time based only the device of interest. For example, since the loT is anticipated to be formed from a large number of devices, a single cell may contain 100s or 1000s of CloT devices. Consequently, in order to reduce potential network congestion and perform load balancing, the network may coordinate allocation of resources to the limited mobility CloT devices such that large number of devices do not transmit and receive data at the same time. For example, if a particular cell includes 10 smart meters which are required to report their readings once a day, the network may stagger the initiation of the NWDM timers which have a period of approximately one day by one minute such that the 10 smart meters do not report their readings at the same time and congest the network. Furthermore, the resources allocated to CloT device that may not communicate time-critical data, may be allocated at off-peak times when there is likely to be relatively little traffic on the network, for example, during the night.

[0079] As shown in Table 3, the duration that a device may stay in the NWDM-On state may vary significantly. For example, a thermostat may report a temperature reading every hour and thus its NWDM timer may be to a duration of an hour. In contrast, a smart utility meter may report a reading only every week. As set out above, during the NWDM-On state it is anticipated that a device does not transmit or receive signals to or from the network. Therefore, synchronisation between the clock at the device and the network may be lost due to clock drift. An implication of this may be that when a device is in the NWDM-On state for a relatively long period of time, the NWDM timers at the network and device may expire at different times i.e. lose synchronisation. Consequently, in order reduce the likelihood of a device missing its pre-allocated resources due to a loss of synchronisation, a margin of error may be provided when setting the NWDM timers or when the network provides a device with an absolute time. For example, even though resources are allocated to the device by the network once each week, the value of the associated timer may be set to less than seven days and the device configured to monitor a plurality of radio frames when it enters the NWDM-Off state such that the device has a reception/transmission window. In this manner, as long as the pre-allocated resources fall within the window the device have access to the resources. This approach therefore introduces a margin of error into the NWDM state transitions timing such lapses in synchronisation between the network and the device due to clock drift can be accommodated and the chance of pre-allocated resources being missed reduced.

[0080] Although through the description of embodiments of the present invention the term Network Disconnected Mode is used, there are a number of differences between a

CloT device being in the NWDM-On state and a conventional non-limited mobility device being disconnected i.e. turned off.

[0081] Firstly, when a CloT device enters NWDM-On state, it retains its context i.e. its IP address, PDN connection, allocated S-GW etc., whereas by turning off a conventional 3GPP device these are lost since the device is no longer considered to be registered with the network. Secondly, when a CloT device transitions form the NWDM-On state to the NWDM-Off state, the device is not required to perform identification, authentication, RRC connection request procedures etc. Instead, these procedures are performed once when the CloT device first registers with the network and the NWDM mode is initially set up. Consequently, as is described in more detail with respect to Figure 7, a CloT device that transitions from a NWDM-On state to the NWDM-Off state may perform relatively few signalling operations in order to transmit or receive data compared to a device which is fully disconnected from the network and thus may make power in comparison to both a device performing DRX and a device which is turned-off in between communication instances.

Mobility Management Signalling [0082] 3GPP compliant devices and networks are conventionally required to perform a range of mobility management protocols such that the location of a device is known to a network, paging messages can be provided to the appropriate base stations, and handover may take place for example. Figure 6 provides a diagram providing an overview of the mobility management signalling that takes in a 3GPP network such as that described with reference to Figure land as set out in 3GPP technical specification TS24.008.

[0083] Although it is beyond the scope of the present application to describe in detail each of the individual procedures set out in Figure 6, of interest to embodiments of the present invention is the location tracking procedure represented by the right hand shaded portion 602 of the Figure 6.

[0084] In conventional 3GPP devices the location tracking procedure is performed at regular intervals in order to ensure that the network has knowledge of the current location of the attached devices. However, regular location tracking and updating may not be necessary if a device can be assumed to be stationary. Consequently, in accordance with the present invention, if a CloT device provides an indication of limited mobility to the network, the network can assume that the device will be stationary on a cellular level and therefore suspend some mobility management procedures. Accordingly, regular location tracking and updating signalling indicated in Figure 6 by the shaded portion may be avoided/suspended thus reducing the communication burden on both the network and the

CloT device and further reducing power consumption in comparison to devices which perform only DRX. However, in order that the network has knowledge of the location of the CloT device, location information may still be required to be obtained/ascertained when the CloT device first registers with the network, when the NWDM is first being set up, or when a device changes moves between base station coverage areas.

Network Disconnected Mode On State [0085] As set out above, according to embodiment of the present invention, a CloT device with limited mobility may transmits and receive data to and from a network with reduced overheads compared to conventional 3GPP terminal devices. A number these signalling overheads are avoided by virtue of the relatively simple procedure which a CloT device with limited mobility performs when it transitions from the NWDM-On state to the NWDM-Off states i.e. reconnects to the network. To illustrate the procedure performed by a CloT device when transitioning from NWDM-On state to the NWDM-Off states, Figure 7 provides a flow diagram showing an example of such a procedure.

[0086] At Step 702 the CloT device is in the NWDM-On state and is disconnected from the network. Consequently, the CloT device is not receiving or transmitting any data but is still registered at the network such that authentication, context establishment etc. are not required to be performed when transitioning to the NWDM-Off state. The state of the device at Step 702 may therefore be considered to correspond to Step 520 of Figure 5.

[0087] At Step 704 the CloT device determines whether the NWDM-On timer has expired. If the timer has not expired, the CloT device remains in NWDM-On state.

However, if the timer has expired the CloT device transitions to the NWDM-Off state and proceeds to Step 706. Alternatively, at Step 705 the CloT may transition to the NWDM-Off state in response to a CloT originating trigger which may be based on factors other than a timer, such as an external environment condition for example.

[0088] At Step 706, the CloT device turns on its receiver and listens to one or more channels physical and logical channels in order to obtain synchronisation information and any downlink signalling which the network is transmitting to the CloT device. For example, the CloT device may listen to a broadcast channel (BCCH) and or a synchronisation channel (SCH).

[0089] At Step 708 the CloT device uses the received synchronisation and broadcast information to synchronise its clock with the network and to establish whether there is downlink data to be received from the network. Alternatively, the information may be used to identify the location of uplink control channel which the device may utilise to request uplink resources. The time taken for synchronisation to take place may vary depending on the extent to which synchronisation has been lost. For example, if the CloT device has a highly accurate clock and/or the CloT device was in the NWDM-On state for a relatively short period of time, any loss in synchronisation is likely to be small and therefore the CloT device will likely be able to quickly locate and receive necessary synchronisation information and signalling data. In contrast, if the CloT device has a lower accuracy clock and/or the CloT device was in the NWDM-On state for a relatively long period of time, the loss in synchronisation is likely to relatively large and therefore the CloT device may take an increased amount of time to locate and receive the necessary synchronisation information and resource signalling.

[0090] Accordingly, in some embodiments, an increased margin for error with respect to NWDM state transition timing may be provided for CloT devices which have lower accuracy clocks and or have a low data transmission frequency. Consequently, devices with reduced accuracy synchronisation may have an increased period of time to perform synchronisation and receive the signalling indicating their allocated resources. In practice and as described above, this margin for error may be provided by setting the timer to values (i.e. the network provided an indication of timer values) such that the timer expires in good time prior to the occurrence of any resources that have been allocated to the relevant CloT device.

[0091] At Step 710, once synchronisation has been performed, the CloT device determines from information supplied by the network when setting up the NWDM or from information obtained in Step 708, whether uplink resources have been pre-allocated.

[0092] At step 718, if it has been determined that uplink resources have not been preallocated to the CloT device, the CloT device proceeds to determine whether to use a random access channel to transmit data to the network. This determination may be based on a parameter set during setting up of the NWDM or in some examples may be dependent on the volume of data which is to be transmitted. For example, if a relatively small volume of data to be transmitted the random access channel may be used and thus the procedure progresses to Step 720, whereas if a large volume of data is to be transmitted the CloT device may request dedicated resources from the network at Step 722.

[0093] At Step 724, once it has been determined that all uplink data has been transmitted in the resources requested in Step 722 and, if required, acknowledged, the CloT device proceeds to Step 716.

[0094] If it is determined that resources have been pre-allocated at Step 710, at Step 712 the CloT device proceeds with transmitting the data to the network in the allocated resources.

[0095] At Step 714, once it has been determined that all uplink data has been transmitted in the allocated resources in Step 712 and, if required, acknowledged, the CloT device proceeds to Step 716.

[0096] At Step 716, if it is determined that the transmission and reception of all data has been completed, the CloT device may then reset the NWDM timer and enter the NWDM-On state, where the timer setting and allocated resources are equivalent to those determined when the NWDM was initially set up upon. Alternatively, an additional negotiation step may take place in which the CloT device and the network re-synchronise the timer and the CloT device is informed of the new timer value or decision parameter and a new set of pre-allocated resources where are to be used the next time the CloT device transitions to the NWDM-Off state.

[0097] In addition to the transmission of data to the network, if it is determined at Step 726 that there is downlink data to be received based on the signalling received in Step 708, the CloT device proceeds with receiving the downlink data from the network at Step 728. Once the downlink data has been received and, if required, acknowledged, the procedure progresses to Step 716 and the CloT device awaits the completion of the transmission of the uplink data. If at Step 726 it is determined that there is no downlink data to be received the procedure progresses to Step 716 and the CloT device awaits the completion of the transmission of the uplink data.

[0098] As previously discussed and as illustrated by Figure 7, the procedure for transitioning from the NWDM-On state to the NWDM-Off state is less complex than when a device first registers with a network and thus power savings are made with respect to a device which fully disconnects from a network after each data transmission. Furthermore, with respect to DRX, location updating, RRC connections requests and the checking of a paging channel is not required and thus power savings are also made with respect to DRX and eDRX.

[0099] Through the description of embodiments of the present invention, the functionality associated with the limited mobility indication and the setting up and implementation of the NWDM has been described as being performed at the CloT device or the network. Accordingly, the CloT device or terminal device may comprise one or more of a receiver, transmitter, controller, and memory configured to perform the functionality described above, Likewise, the network is formed from number of separate elements each with their own specific functionality as described with reference to Figure 1. Accordingly, the functionality said to be performed by the base station or network may be performed by one or more appropriately configured elements of the network. For example, the core network may coordinate and perform the setting of the context of limited mobility CloT devices and setting up of the NWDM, whereas the base stations may perform the generation and synchronisation of the synchronisation signals.

[00100] The UE functionality described above may be implemented on a multiple purpose processor which executes computer readable instructions stored on a computer readable medium which when executed configure the multiple purpose processor and peripheral components to perform the functionality described with reference to the example embodiments.

[00101] The network functionality described above may be implemented on a multiple purpose processor which executes computer readable instructions stored on a computer readable medium which when executed configure the multiple purpose processor and peripheral components to perform the functionality described with reference to the example embodiments [00102] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[00103] Features, integers or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[00104] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[00105] The various embodiments of the present invention may also be implemented via computer executable instructions stored on a computer readable storage medium, such that when executed cause a computer to operate in accordance with any other the aforementioned embodiments.

[00106] The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. 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.

References 3GPP TR45.820 v1.4.0 - 27/07/2015 - http://www.3gpp.org/DynaReport/45820.htm 3GPP TS24.008 v12.2.0 - 26/06/2015 - http://www.3gpp.org/DynaReport/24008.htm 3GPP TS22.368 v13.1.0 - 19/12/2014 - http://www.3gpp.org/DynaReport/22368.htm

Claims

CLAIMS:

1. A method of operating a terminal device for receiving data from and transmitting data to a mobile communications network, the mobile communications network including a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, the method comprising: receiving, from the base station, one or more signals identifying the base station; and transmitting, to the base station, registration information for registering the terminal device with the mobile communications network, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

2. The method of claim 1, wherein the mobility indicator indicates the terminal device will be either stationary or moving within a boundary relative to the geographical coverage area provided by the base station.

3. The method of claims 1 or 2, wherein the method comprises: periodically transmitting a volume of user plane data to the base station, and the registration information includes at least one of an indication of the volume of the user plane data, and an indication of the temporal frequency of the periodic transmission

4. The method of claim 3, wherein the method comprises: entering a reduced-power state at the terminal device for a predetermined period between the periodic transmissions of the volume of user plane data.

5. The method of claims 3 or 4 wherein the method comprises: receiving, from the base station, an indication of an uplink resource allocation in which to transmit the volume of user plane data; and entering a reduced-power state at the terminal device for a predetermined period prior to the indicated uplink resource allocation.

6. The method of claims 4 or 5, wherein the method comprises: receiving, from the base station, an indication of the predetermined period.

7. The method of claim 6, wherein the indication of the predetermined period includes a timer value, and the method comprises: initiating a timer with the timer value in response to entering the reduced-power state, and exiting the reduced-power state in response to expiry of the timer.

8. The method of claims 3 or 4, wherein transmitting the volume of user plane data to the base includes transmitting the volume of user plane data in a random access channel.

9. A method of operating a mobile communications network for transmitting data to and receiving data from a terminal device, the mobile communications network including a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, the method comprising: transmitting, to the terminal device, one or more signals identifying the base station; receiving, from the terminal device, registration information for registering the terminal device with the mobile communications network; and registering the terminal device with the mobile communications network based upon the registration information, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

10. The method of claim 9, wherein the mobility indicator indicates the terminal device will be either stationary or moving within a boundary relative to the geographical coverage area provided by the base station.

11. The method of claims 9 or 10, wherein the method comprises: periodically receiving a volume of user plane data from the terminal device, and the registration information includes at least one of an indication of the volume of the user plane data, and an indication of the temporal frequency of the periodic transmission.

12. The method of claims 11, wherein the method comprises: determining an allocation of uplink resources in which to receive volume of user plane data based on one or more of the indication of the volume of the user plane data and the indication of the temporal frequency of the periodic transmission; and transmitting, to the terminal device, an indication of the determined uplink resource allocation.

13. The method of claim 12, wherein the terminal device is configured to enter a reduced-power state for a predetermined period prior to the indicated uplink resource allocation, and the method comprises: determining the predetermined period based on the indication of the temporal frequency of the periodic transmission; and transmitting, to the terminal device, an indication of the predetermined period.

14. The method of any of claims 9 to 13, wherein the mobile communications network is configured to transmit a location update request to terminal devices registered with the mobile communications network, and the method comprises: suspending, in response to receiving the mobility indicator, the transmission of location update requests to the terminal device.

15. The method of claim 11, wherein the registering includes generating connection context information for the terminal device, and the method comprises: maintaining the connection context information between the periodic reception of the volume of user plane data.

16. A mobile communications network for transmitting data to and receiving data from a terminal device, the mobile communications network including a core network and a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, wherein the base station is configured to transmit, to the terminal device, one or more signals identifying the base station; and receive, from the terminal device, registration information for registering the terminal device with the mobile communications network; and the core network is configured to register the terminal device with the mobile communications network based upon the registration information, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

17. A terminal device for receiving data from and transmitting data to a mobile communications network, the mobile communications network including a base station configured to transmit data to and receive data from the terminal device when the terminal device is located within a geographical coverage area provided by the base station, wherein the terminal device comprises: a receiver configured to receive, from the base station, one or more signals identifying the base station; and a transmitter configured to transmit, to the base station, registration information for registering the terminal device with the mobile communications network, wherein the registration information includes a mobility indicator indicating the mobility of the terminal device relative to the geographical coverage area provided by the base station.

18. A terminal device as substantially hereinbefore described with reference to the accompanying drawings.

19. A mobile communications network as substantially hereinbefore described with reference to the accompanying drawings.