AU2021203896B2

AU2021203896B2 - Resource management in telecommunications networks

Info

Publication number: AU2021203896B2
Application number: AU2021203896A
Authority: AU
Inventors: David Iain Aders; Mark Andrew Farrell; Paula Mary Rujak; Michael James Ross Swadling; Nicholas Andrew Tompson; Joakim ÅKESSON
Original assignee: Telstra Corp Ltd
Current assignee: Telstra Corp Ltd
Priority date: 2015-11-09
Filing date: 2021-06-11
Publication date: 2022-11-17
Anticipated expiration: 2036-11-09
Also published as: AU2021203896A1; AU2016256738A1

Abstract

A method of managing utilisation of cellular mobile telecommunications network infrastructure, including: connecting to a device which stores or has access to network 5 selection information identifying at least two different logical mobile telecommunications networks to which the device is permitted to connect, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure; transmitting to the device a priority list of radio frequencies, each frequency in the list being associated with a priority, the priorities 10 in the list at least in part determining the order in which the device will use the respective associated frequencies during cell selection or reselection; and before attempting handover to a target cell of the device from a serving cell to which the device is connected, querying prohibited target cell information to determine whether handover to the target cell should be initiated, wherein the content of the network selection information, priority list and 15 prohibited target cell information at least in part depends upon whether the device is associated with a priority user account. Ul L.n (D Ln ((D CLC -b CL

Description

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This application is a divisional of Australian Patent Application No. 2016256738, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the present invention broadly relate to methods and systems for enabling priority utilisation of a mobile telecommunications network. For example, specified classes of users may be given priority over other users in using parts or all of a telecommunications network.

BACKGROUND

Conventional telecommunications networks do not discriminate amongst subscribers. For generally available commercial networks, subscriber discrimination is generally not necessary. However, in some circumstances it would be useful for subscribers to have greater certainty that they can use part or all of a telecommunications network when required.

For example, employees working in large areas (such as in a mine site) may wish to communicate with each other over a mobile telecommunications network, without the possibility that performance of that network will be degraded by non-employee use. Emergency services personnel also require priority access to a telecommunications network.

One approach to addressing these needs is to build private telecommunications networks using commercially available equipment. Although building dedicated network infrastructure would ensure priority (or dedicated) access for a selected set of users, be they employees of an organisation or emergency service personnel, it comes at a substantial capital cost. Although this cost may be avoided by having the selected set of users utilise the existing public or general commercial telecommunications networks, the resources of those networks are shared amongst a large number of commercial and

I individual customers, reducing the extent to which the selected users can reliably gain access to the network resources they require.

Addressing the aforementioned difficulties requires overcoming substantial technical hurdles. It is desired to address or ameliorate one or more of the aforementioned difficulties, or other disadvantages or drawbacks of the prior art, or at least provide a useful alternative.

SUMMARY

In at least one embodiment, the present invention provides a method of managing utilisation of cellular mobile telecommunications network infrastructure, including: connecting to a device which stores or has access to network selection information identifying at least two different logical mobile telecommunications networks to which the device is permitted to connect, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure; transmitting to the device a priority list of radio frequencies, each frequency in the list being associated with a priority, the priorities in the list at least in part determining the order in which the device will use the respective associated frequencies during cell selection or reselection; and before attempting handover to a target cell of the device from a serving cell to which the device is connected, querying prohibited target cell information to determine whether handover to the target cell should be initiated, wherein the content of the network selection information, priority list and prohibited target cell information at least in part depends upon whether the device is associated with a priority user account.

In at least one embodiment, the present invention provides one or more components of a mobile telecommunications network infrastructure configured to execute the above mentioned method.

In at least one embodiment, the present invention provides a cellular mobile telecommunications network infrastructure configured to: connect to a device which stores or has access to network selection information identifying at least two different logical mobile telecommunications networks to which the device is permitted to connect, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure; transmit to the device a priority list of radio frequencies, each frequency in the list being associated with a priority, the priorities in the list at least in part determining the order in which the device will use the respective associated frequencies during cell selection or reselection; and after commencement of an attempted handover to a target cell of the device from a serving cell to which the device is connected, query the prohibited target cell information to determine whether handover to the target cell should proceed, wherein the content of the network selection information, priority list and prohibited target cell information at least in part depends upon whether the device is associated with a priority user account.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a schematic diagram of a portion of an exemplary mobile telecommunications network; Figure 2 is an example of an ATTACH ACCEPT message; Figure 3 is an exemplary attachment process; Figure 4 is an example of part of a System Information Block Type 5 (SIB5) message; Figure 5 is an example of part of a System Information Block Type 3 (SIB3) message;

Figure 6 is an example of part of an RRC Connection Release message; Figures 7 and 8 together are an exemplary process for transmitting a priority list of radio frequencies to a device in an LTE-based telecommunications network; Figure 9 is an example of a MeasurementReport message; Figure 10 is an example of an RRCConnectionReconfiguration message; Figure 11 is an exemplary handover process; Figure 12 is an exemplary process for managing utilisation of a cellular mobile telecommunications network; Figure 13 is an exemplary process for allocating resources undertaken by a mobile telecommunications network infrastructure; Figure 14 an example of part of a System Information Broadcast message containing access class barring information; Figure 15 is an exemplary process undertaken by a mobile telecommunications network infrastructure for restricting the number of devices attempting to seek access to it; Figure 16 is an exemplary process for determining whether the utilisation of resources within a telecommunications network infrastructure is greater than a congestion threshold; Figure 17 is an example of part of an RRC connection request; Figure 18 is an exemplary RRC Admission Control procedure in an LTE-based network; Figures 19A and 19B are exemplary processes for creating a bearer in an LTE based network; and Figures 20 and 21 are exemplary processes for load-triggered handover.

DETAILED DESCRIPTION

Access to modem mobile telecommunications networks is nearly ubiquitous in many first world cities. Devices such as mobile telephone handsets, tablets, laptop computers and other portable computing devices increasingly use mobile telecommunications networks for the transfer of data, and of course mobile telecommunications networks are used to route calls from a calling party to a called party.

The infrastructure of a mobile telecommunications network may be broadly divided into two parts. As illustrated in Figure 1, a radio access network (commonly abbreviated to RAN) 20 of a mobile telecommunications network 10 allows communications from a mobile device 30 (illustrated, for the purposes of an example only, as a mobile telephone handset) to a base station 40 through a base station antenna 50. Communications between base stations 40 to other resources (such as a gateway 60 to the Internet 70) takes place over the "core" network 80.

Many resources of a mobile telecommunication network are shared between users. For example, a base station can typically maintain a simultaneous connection with a fixed number of mobile devices, and the data transfer rate attainable by each those devices often depends on the data requirements of the other devices connected to the same base station.

Although sharing of resources leads to efficient usage of those resources, it increases the possibilities of congestion and of reduced availability. Some classes of users, such as emergency service workers, require a higher availability and lower congestion than other classes of users. These "priority users" may use dedicated mobile telecommunications network infrastructure to avoid or minimise congestion. However, in embodiments of the present invention, the devices used by "priority users" (that is, devices associated with a priority user account) are given access to a dedicated logical mobile telecommunications network. This dedicated logical mobile telecommunications network shares some parts of the mobile telecommunications network infrastructure with other logical mobile telecommunications networks, but allows for at least a portion of the RAN resources to be separated amongst classes of users.

Any mechanism may be used to identify or differentiate the logical mobile telecommunications networks which share mobile telecommunications network infrastructure. For example, one or more network identifiers may be stored in a location to which a device, connected to the network, has access. The device may consult the one or more (for example, a list of) network identifiers to identify the logical mobile telecommunications networks with which it is permitted to connect. The list of network identifiers may be stored on the device, on a component inserted into the device or of the device (such as a standard Subscriber Identity Module (SIM), a Universal Integrated Circuit Card, or a reprogrammable SIM), or at any other storage location accessible to the device.

The use of a list of logical mobile telecommunications network identifiers enables priority users to have dedicated and exclusive access to at least one of the logical mobile telecommunications networks. Devices associated with priority user accounts, referred to in this document as "priority devices", may be associated with a list of network identifiers, which may consist of only a single identifier identifying a single dedicated logical mobile telecommunications network, or multiple identifiers identifying a plurality of dedicated logical mobile telecommunications networks. Devices not associated with priority user accounts, referred to in this document as "non-priority devices", may be associated with a different list of network identifiers, which does not contain entries identifying any of the dedicated logical mobile telecommunication networks, but instead only contains entries identifying general access telecommunications networks.

As described above, a device may store or have access to network selection information (for example, in the form of a list of network identifiers) identifying at least two different logical mobile telecommunications networks, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure. The content of the network selection information may depend on whether the device is associated with a priority user account, i.e., whether the device is a "priority device". For priority devices, the network selection information would include information identifying at least a dedicated logical mobile telecommunications network. For non-priority devices, the network selection information would only include information identifying one or more general access mobile telecommunications networks, and would not include any information identifying a dedicated logical mobile telecommunications network, even though both the general access mobile telecommunications networks and the dedicated logical mobile telecommunications networks are accessible by use of the mobile telecommunications network infrastructure.

In some circumstances, it may be desired to give priority users access to both dedicated logical mobile telecommunications networks and general access telecommunications networks. In such circumstances, the priority devices may store or have access to network selection information identifying at least two different logical mobile telecommunications networks (one of which is a dedicated logical mobile telecommunications network, and another of which is a general access logical mobile telecommunications network), each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure.

In some embodiments, the logical mobile telecommunications networks may take the form of Public Land Mobile Networks (PLMNs). Each PLMN is associated with an identifier, which may be referred to as a PLMN code. PLMN codes may consist of a 3-digit Mobile Country Code (MCC), and a 2 digit Mobile Network Code (MNC). Accordingly, in some embodiments the network selection information accessible to the mobile device may take the form of one or more combinations of MCCs and MNCs. An example of such a combination is 505 01. 505 is the MCC which identifies Australia, and 01 identifies a logical mobile telecommunications network operated by Telstra Corporation Limited (an Australian telecommunications network provider).

Conventionally, devices have a single "home" PLMN (HPLMN), which identifies a single logical mobile telecommunications network to which the device is permitted to connect. However, in embodiments of the present invention, devices may be associated with one or more additional PLMNs (which could be in the form of equivalent PLMNs, or E-PLMNs), enabling devices to use more than one PLMN. The PLMNs associated with a device are at least in part dependent upon whether the device is a priority device. Priority devices are associated with different network selection information (which, for example, may take the form of an E-PLMN list) to devices that are not priority devices (that is, are not associated with a priority user account).

A device may be "associated" with an account in any way which ties the device to a user or customer account. For example, a device may contain a device identifier (such as an

IMEI). Alternatively, a device may contain other hardware that contains a device identifier (such as an IMSI, which is typically stored on a SIM).

The network selection information may be sent to the device using the cellular mobile telecommunications network infrastructure. In one embodiment, the network infrastructure uses the device IMSI to identify whether the device is a priority device (that is, whether the device is associated with a priority user account), and consequently determine the contents of the network selection information sent to the device.

The device transmits its IMSI to the network infrastructure during the initial process by which it attaches to the network. This IMSI (or other device identifier) is used to query a database which stores an association of the IMSI or other identifier with user accounts (or characteristics of user accounts).

In embodiments, the IMSI (or information which can be used to determine an IMSI, such as a temporary identifier) is passed to a Mobile Management Entity (MME), which stores or has access to a database which stores an association of ranges of IMSIs with corresponding information which identifies whether accounts associated with that range are priority user accounts. If the MME determines that the device is a priority device, it will send to the base station (for forwarding to the device) network selection information that includes, for example, information identifying a dedicated logical mobile telecommunications network. However, if the MME determines that the device is not associated with a priority user account, i.e., the device is a "non-priority device", it will send to the base station network selection information that does not include information identifying a dedicated logical mobile telecommunications network.

The network selection information may be sent to the device during an authentication process. For example, a device may need to authenticate to part of the mobile telecommunications network infrastructure to enable the device to communicate useful data over the infrastructure. This could involve setting up a default bearer, in the case of an IP-based network, to ensure that the device has IP connectivity with the network. A device may send an initiating message requesting connectivity with the telecommunications network infrastructure. This may initiate a message exchange which could involve requests for identity and reconfiguration messages. Any messages sent from the mobile telecommunications network infrastructure to the device during this initial authentication or connectivity setup process may include the network selection information.

Where the cellular mobile telecommunications network infrastructure follows an industry standard specification (such as those promulgated by the3 rd Generation Partnership Project (3GPP)), that standard may describe a suitable message which may include the network selection information. For example, as shown in Figure 2, an ATTACH ACCEPT message 200 that is included in an RRC Connection Reconfiguration message may include network selection information in the form of a list of Equivalent PLMNs 210.

The network selection information may be sent only once to the device, during initial provisioning. Alternatively, it may be sent more regularly to the device, for example each time the device attaches to a new base station, or periodically.

As indicated above, the content of the network selection information at least in part is dependent upon whether the device is associated with a priority user account. If the device is such a "priority device", the network selection information it will receive will differ from the network selection information that will be sent to other devices. In one example, priority devices are sent network selection information which identifies both a dedicated logical mobile telecommunications network, and a general access logical mobile telecommunications network, while other devices are sent network selection information which does not identify any dedicated logical mobile telecommunications networks.

As described above, the network selection information may be sent to the device during an authentication or provisioning process. An exemplary attachment process (by which a device attaches to a logical mobile telecommunications network) will now be described with reference to Figure 3.

At step 302, the device (or User Equipment, UE) begins the ATTACH procedure by attempting to become RRC connected. If the procedure is successful, the UE sends to the network an ATTACH REQUEST message (step 304). This message includes an IMSI, which uniquely identifies the UE. This ATTACH REQUEST message is sent to the MME (step 306), which determines whether the UE is associated with a priority user account by requesting, at step 308, subscription information from the Home Subscriber Server (HSS). Based on the subscription information retrieved from the HSS, the MME is able to determine whether the IMSI that was included in the ATTACH REQUEST message is associated with a priority user account (step 310). If the IMSI is not associated with a priority user account, the MME instructs base station (or eNodeB) to establish a normal (non-priority) bearer with the device (step 312). At step 314, the MME sends the Home Location Register (HLR) for the subscriber (which, in this case, is a non-priority user) to the eNodeB. The attachment process will then either fail or succeed based on, amongst other things the congestion level of the eNodeB.

However, if at step 310 the MME determines, based on the subscription information received from the HSS, that the UE is associated with a priority user account, at step 316 the MME instructs the eNodeB to create a high priority bearer for the UE. This bearer will not only include a Subscriber Profile Identifier (SPID), it will also include Allocation and Retention Priority (ARP) and Quality of Service Class Identifier (QCI) parameters. After sending the HRL for the priority subscriber to the eNodeB at step 318, the MME instructs the eNodeB to send an Equivalent PLMN list to the UE (at step 320). This list will include information identifying at least one dedicated logical mobile telecommunications network, and, in some circumstances, will also include information identifying at least one general access telecommunications network.

Although priority devices which receive network selection information identifying both dedicated and general access logical mobile telecommunications networks can connect to any of the networks identified in the network selection information, it may be preferable for priority devices to use a dedicated logical mobile telecommunications network where appropriate. This is because priority devices will not need to share resources with non priority devices (that is, devices not associated with priority user accounts) when using dedicated logical mobile telecommunications networks.

In some configurations, different logical mobile telecommunications networks use different radio frequencies to communicate with devices. For example, a dedicated logical mobile telecommunications network may use a different radio frequency to a general access logical mobile telecommunications network. In such configurations, priority devices may be sent a priority list of radio frequencies. The priority list may contain a set of frequencies, each frequency being associated with a priority. The priorities in the list may, at least in part, determine the order in which the devices will use the respective associated frequencies during cell selection or reselection.

A device which communicates with cellular mobile telecommunications network infrastructure maintains a connection with a base station of the network infrastructure when within range of that base station. As the device moves within the area serviced by the infrastructure, it disconnects and reconnects with different base stations. When the device is actively communicating across the infrastructure, it is said to be in "active mode". However, when the device is turned on and available to communicate across the infrastructure, but is not in fact doing so, it is in "idle mode". In both idle mode and active mode, a device is associated with a suitable base station to which it can connect using radiofrequency communication. When a device wishes to institute a communication, and is connected to a base station in idle mode, it will endeavour to maintain that connection and convert it from an idle mode connection to an active mode connection.

A device may communicate with a base station using a variety of radio frequencies. Where one frequency becomes inappropriate (for example due to congestion on that frequency), the device may attempt to reconnect with the base station using a different frequency. Where this "cell reselection" occurs during idle mode, there is no impact on the user of the device because there is no active communication occurring over the network infrastructure. It follows that if idle mode cell reselection can be appropriately controlled, the device may be "biased" to actively communicate on a particular frequency by causing it to communicate with a base station using that frequency in idle mode. It follows that controlling the frequencies (or, where there are multiple logical mobile telecommunications networks differentiated by frequency, the logical telecommunications networks) on which a device will communicate in idle mode also has the effect of controlling the frequencies or logical telecommunications networks on which the device will preferentially communicate in active mode.

In an embodiment in which different logical mobile telecommunications networks use different frequencies with which to communicate between base stations and devices, devices may be biased towards using one logical mobile telecommunications network (such as a dedicated logical mobile telecommunications network) instead of another (such as a general access logical mobile telecommunications network). This may be achieved by transmitting to a device the priority list of radio frequencies referred to above, for use by the device during idle mode cell selection or reselection (i.e. during circumstances where the device is attempting to initiate an idle mode connection with a logical mobile telecommunications network).

Each frequency in the priority list may be associated with a priority, which may be an integer number. The greater the integer number, the higher the priority. During cell selection or reselection, the device queries the list to determine the highest integer priority, and in turn identifies the associated frequency. It then attempts to communicate on that frequency with base stations within range, and determines whether the communications with those base stations will be of sufficient quality. It determines whether the communications will be of sufficient quality by comparing some measured communications parameters (such as received signal strength) with predetermined thresholds. If there is a base station with which the device can communicate on the selected frequency, and the communication parameters meet the required thresholds, the device then "camps" on that frequency. However, if there is no such base station, the device moves down the list to the next highest integer priority, and attempts to communicate on the frequency associated with this next priority.

A priority device may be sent a different priority list to one that is sent to non-priority devices. Most usefully, the priority list sent to the priority device would have frequencies associated with dedicated logical mobile telecommunications networks at the highest priority levels. In contrast, the priority list sent to the non-priority devices would not contain any entries referring to frequencies associated with dedicated logical mobile telecommunications networks. In this way, priority devices would be biased towards using priority networks, while non-priority devices would be unable to camp on priority networks.

In some telecommunications networks that implement features described in telecommunications standards associated with Long Term Evolution (LTE) (or 4G) networks, each LTE cell can broadcast a list of frequencies for which a device should search for a cell to camp on, in a part of a message called System Information Block Type 5 (SIB5), an example of part of which is shown as item 400 in Figure 4. Each of these frequencies 420 has an associated priority 410 (referred to in Figure 4 by the field CellReselectionPriority). System Information Block Type 5 is broadcast in SIB3, an example of part of which is shown as item 500 in Figure 5, and includes the priority of the current cell 510. The device will attempt to camp on a cell (or frequency) that has a higher priority than its current cell (or frequency).

Priority devices may have these broadcast values overridden by values in an override message, which may take the form of an RRC Connection Release message, an example of part of which is shown as item 600 in Figure 6. A first frequency 610 (having a value of 1300) is associated with a priority 615 (having a value of 5). A second frequency 620 (having a value of 630) is associated with a second priority 625 (having a value of 7). A third frequency 630 (having a value of 3608) is associated with a third priority 635 (having a value of 3).

When a priority device goes idle after attaching to a logical mobile telecommunications network, it will receive the new priority list of radio frequencies in the override message. As described above, the priority device will measure communication quality parameters for each of the frequencies in the priority list (in order of their identified priority), and camp on the first frequency which enables it to communicate at a sufficient quality.

In some embodiments, the contents of the override message may be determined for each user. In other embodiments, a determination is first made of whether the user device is a priority device, and the content of the priority list (whether sent in a broadcast SIB or an override message) is determined based on whether the user device is a priority device.

When a device first connects to a logical mobile telecommunications network, an initial message exchange occurs. During that message exchange, an identifier for the device may be sent to the network. For example, in some network configurations, an identifier in the form of a Subscriber Profile ID (SPID) may be sent to the network as part of an initialContextSetup message. In a database accessible to the network, this SPID is associated with additional information which identifies whether the SPID corresponds to a priority user account.

An exemplary process for transmitting to a device a priority list of radio frequencies in an LTE-based telecommunications network is illustrated in Figures 7 and 8, which should be considered together. Referring initially to Figure 7, the process commences when the UE has not sent or received data for a period of time (702). As a result, in step 704 the eNodeB informs the MME that the UE has been idle for longer than a threshold period. At step 706, the MME instructs the eNodeB to release the UE. The eNodeB, using information obtained about the UE during prior handover or attach procedures (for example, those described above with reference to Figure 3) determines if the UE is associated with a priority user account (step 708). If the device is not a priority device (that is, is not associated with a priority user account), the eNodeB sends an RRC Connection Release message to the UE which does not contain an idleModeMobilityControllnfo information element (step 710). However, if at step 708 the eNodeB determines that the UE is associated with a priority user (that is, is a priority device), the eNodeB will send the UE an RRC Connection Release message which does contain an idleModeMobilityControllnfo information element (step 712). The content of this information element prioritises the frequencies associated with one or more dedicated logical mobile telecommunications networks.

Referring now to Figure 8, when the UE is in idle mode, it reads the System Information Broadcast messages (examples of which are referred to above) sent by the serving eNodeB to determine the set of frequencies it should use in its cell reselection search procedure (including their associated priorities) (step 802). If the UE was provided with priority information in the idleModeMobilityControl information element of the RRC Connection Release when it was released (see step 712 of Figure 7) the UE uses the information provided in the RRC Connection Release message instead of that provided in the SIB message (step 804). At step 806, the UE uses the frequency and priority information (provided in the RRC Connection Release message in the case of a priority device, and provided in the SIB message in the case of a non-priority device) to determine the order in which it will search for cells to associate with. When the UE finds a cell, it first checks if that cell is broadcasting an identifier contained in the network selection information which the UE stores or has access to. The identifier could be the Home PLMN identified in the network selection information (step 808), or a member of the UE's equivalent PLMN list (step 810). If the identifier is contained in the network selection information, the UE will then determine if the cell quality is good enough to reselect to the new cell (step 812). If this final check is passed the cell will reselect and associate with the new cell, at step 814). If any of the checks are failed the UE will continue to search for a new cell that meets all the criteria.

A priority device will receive an RRC Connection Release message having an idleMode MobilityControl information element which contains the frequencies of one or more dedicated logical mobile telecommunication networks at the highest priority, and will store or have access to network selection information identifying the dedicated logical mobile telecommunications networks. This will cause priority device to preferentially use dedicated logical mobile telecommunications networks. Non-priority devices, which will have a priority list which does not contain frequencies associated with dedicated logical mobile telecommunications networks, and which do not have network selection information identifying a dedicated logical mobile telecommunications network, will preferentially use general access mobile logical mobile telecommunications networks.

To maintain the quality of connections between devices and mobile telecommunications networks, devices may be configured to move between "cells" of the mobile telecommunications network. A device that communicates using the network is attached to a "cell" of the network. In this context, a cell is defined by both frequency and geography. That is, a cell is defined by its location and the frequencies it uses to communicate between mobile devices and a base station. It follows that a single base station may be associated with more than one cell, as it may communicate using more than one frequency band and/or serve more than one geographic area.

A cell will be a "neighbour" of another cell if it is adjacent to the cell geographically, or if it shares the same base station and differs only by frequency band.

Where a device is connected to a cell of a mobile telecommunications network, it may be configured to monitor communication parameters associated with a neighbour cell. An example of a suitable communication parameter is received signal strength. Other suitable communication parameters may include Reference Signal Received Quality (RSRQ) and Reference Signal Received Power (RSRP). Where the communication parameter of a neighbour cell, when compared with the same parameter of the cell to which the device is currently attached, suggests that communication with a neighbour cell is likely to result in better connection quality, preparation for a handover process is commenced. Preparation for a handover process may also be commenced where a communication parameter associated with the cell to which the device is currently attached reaches a predetermined threshold.

For example, where received signal strength is used as a communication parameter, the device may monitor the received signal strength of a neighbouring cell. Where the received signal strength of that neighbouring cell is greater than that of the current (serving) cell by a predetermined amount (for example 3 dB), the mobile telecommunications network infrastructure (e.g. the eNodeB) may commence preparation for handing the device over to the neighbouring cell. Alternatively, where the signal strength of the serving cell drops below a threshold, the device may start measuring the received signal strength of neighbouring cells to identify a potential handover target.

The base station of the network may configure the relevant handover preparation triggers by sending an appropriate message to the device. For example, in standards based 4G networks, an eNodeB may inform the device of the frequencies it should be monitoring and the communication parameter thresholds to be met for the device to report to the eNodeB that a potential handover target neighbour has been identified. The message used by the eNodeB to provide this information to the device may be an RRCConnectionReconfiguration message.

As indicated above, a neighbouring cell could be a different frequency band on the same base station as the serving cell. In embodiments where the dedicated logical mobile telecommunications networks operate using different frequencies to the general access logical mobile telecommunications networks, it may therefore be possible for devices to handover from a general access logical mobile telecommunications network cell to a dedicated logical mobile telecommunications network cell. This could result in a non priority device communicating using a dedicated logical mobile telecommunications network. This may have a deleterious effect on the services provided to the priority users, and is thus undesirable.

In some embodiments, the handover process involves the base station (or some other part of the mobile telecommunications network infrastructure) instructing the device to handover to an identified neighbour cell. The process of identifying the neighbour cell may differ in implementations. Nevertheless, ultimate control over whether handover occurs is, in embodiments, the responsibility of part of the mobile telecommunications network infrastructure.

Accordingly, in embodiments, the mobile telecommunications network infrastructure stores, or has access to, prohibited target cell information. This prohibited target cell information identifies target cells to which handover should not occur. During handover preparation, and before handover of a device to a target cell is commenced, part of the mobile telecommunications network infrastructure (for example, the base station or eNodeB) queries the prohibited target cell information to determine whether the handover to the target cell should proceed. If the target cell is identified in the prohibited target cell information, the handover process will not proceed.

The content of the prohibited target cell information at least in part depends on whether the device is a priority device.

In some embodiments, when a device first attaches to the network, the base station (or eNodeB) determines the relevant prohibited target cell information. This prohibited target cell information may be sent to the base station, upon device attachment, from another part of the mobile telecommunications network infrastructure (such as a Mobility Management Entity (MME)). The identification of relevant prohibited target cell information, by the base station or other part of the mobile telecommunications network infrastructure, may use an identifier of the device (such as the IMSI associated with the device). In some embodiments, the MME stores prohibited target cell information associated with a range of IMSI. If the IMSI of the device which attaches to the network is one which is associated with prohibited target cell information, it is that prohibited target cell information that is sent to the base station. In some configurations the base station itself may store the prohibited target cell information and the associated IMSI data.

As indicated above, the handover process involves the mobile telecommunications network infrastructure instructing the device to handover to an identified neighbour cell. There may be many other steps preparatory to the commencement of this handover process. For example, as described above the device may be configured to report when there is a potential handover target (based, for example, on a comparison of received signal strength). This report may take the form of a MeasurementReport, in standards-based network implementations. Where the report does not uniquely identify each of the neighbouring cells which is a potential handover target, the base station may take steps to identify, either by itself or with the assistance of further information received from the device, the unique identifier of the potential handover target cells. Once the unique identifier has been determined, it may be compared with the prohibited target cell information (retrieved based on a received device identifier such as an IMSI, or other connection context values or parameters), to determine whether handover to the target cell should be initiated.

An example of a MeasurementReport is shown as 900 in Figure 9. Two potential neighbouring target cells are non-uniquely identified by their Physical Cell ID ("physCellID", or PCI). One potential handover target has a PCI of 341 (910), and another has a PCI of 89 (920). The eNodeB uses the PCIs to determine unique identifiers for the potential handover targets, which may take the form of an E-UTRAN Cell Global ID (eCGI). As a first step, the eNodeB interrogates an internally maintained neighbour list. If this list does not contain the PCI, it may ask the device to report the eCGI of the potential handover target. It may do so by sending the device a message, such as an RRCConnectionReconfiguration message, an example of which is shown in Figure 10. As can be seen from item 1010, the RRCConnectionReconfiguration message of Figure 10 requests the device to obtain the eCGI of the neighbouring cell having a PCI of 341.

The device will then listen for a message from the potential handover target which will include the eCGI. Such a message may be a System Information Block Type 1 message. The eCGI may then be sent from the device to the initiating or source eNodeB, for example in a MeasurementReport message.

The prohibited target cell information may take the form of a list of Tracking Area Codes (TACs). Alternatively or in addition, the prohibited target cell information may include information identifying logical mobile telecommunications networks (for example, in the form of PLMN identifiers) and Location Area Codes (LACs), or any other information that may be used to identify prohibited target cells.

Figure 11 illustrates a summary of the above handover process. As described above, where the quality of a connection that a device (such as a UE) has with a base station (such as an eNodeB) drops below a threshold level, a handover process is commenced. The connection quality may be measured by a CQI (Channel Quality Information) parameter, calculated periodically by the UE based on measured channel quality.

The illustrated handover process starts when the UE moves into an area with poor coverage from the serving cell (1102). At step 1104, the eNodeB checks whether the UE is associated with a priority user account (as described in further detail above). During the handover process, the UE receives a list of frequencies which the UE uses when searching for alternative handover target cells. If the UE is associated with a priority user account (i.e., the UE is a priority device), the eNodeB will include priority frequencies (frequencies associated with a dedicated logical mobile telecommunications networks) in the list of frequencies it sends to the UE (step 1106). If the UE is not associated with a priority user account (i.e., the UE is a non-priority device), the eNodeB will not include the priority frequencies in the list of frequencies sent to the UE (step 1108).

At step 1110, the UE searches each frequency in the list it was sent by the eNodeB to identify a suitable handover candidate cell. At step 1112, the UE measures whether the candidate cell at the highest priority in the frequency list has a better channel quality than the serving cell. If the channel quality of the candidate cell is not better than the channel quality of the current serving, the UE continues searching (step 1110) by working down the frequency list in order of priority. If a candidate handover cell is identified having a better channel quality than the serving cell, the UE sends a measurement report (such as an RRC Measurement Report) to the eNodeB (step 1114). The eNodeB then checks if the Tracking Area Code (TAC) of the neighbouring cell is in the Handover Restriction List (HRL) for the UE (step 1116). If the TAC is in the HRL, handover to that cell is not permitted, and the UE is instructed to continue searching, returning to step 1110. If the TAC of the neighbour cell is not in the HRL, handover is permitted and the eNodeB sends the UE an instruction to handover to the neighbouring cell (step 1118).

An exemplary method for managing utilisation of a cellular mobile telecommunications network, which includes some of the aforementioned described methods, is illustrated in Figure 12. At step 1210 a device connects to the cellular mobile telecommunications network, for example by establishing an exchange of messages with a base station of the network. At step 1215, the device sends a message to the network which indicates a characteristic of the device or associated SIM card (such as an IMEI). The message may take the form of an ATTACH REQUEST message as described above. Upon receipt of the message, at step 1220, an element of the cellular mobile telecommunications network infrastructure, such as a core network element (for example a Mobility Management entity) determines whether the characteristic of the device is associated with a priority user account. If the characteristic of the device is associated with a priority account (that is, the device is a priority device), at step 1225 the device is sent network selection information which, as described above, may take the form of an E-PLMN list. At step 1230, the priority device is sent a first priority list of radio frequencies, which prioritise a dedicated logical mobile telecommunications network as described above. If the device is not a priority device, it is sent at step 1235 a second, different priority list of frequencies which does not include any frequencies associated with the dedicated logical mobile telecommunications network.

At a later point in time, the device may move within the service area of the cellular mobile telecommunications network infrastructure, such that it is closer to a different base station. At step 1240, a node within the cellular mobile telecommunications network infrastructure receives information identifying a potential handover target. Again, at step 1245, a determination is made as to whether the device is a priority device. If the device is a priority device, the node within the network responsible for handover (such as an MME) queries first prohibited target cell information to determine whether the handover target is on the prohibited list (step 1250). If the device is not a priority device, second prohibited target cell information is queried (step 1255). The second prohibited target cell information will include information identifying cells which are associated with the dedicated logical mobile communications network. Accordingly, if the potential handover target base station is in the second prohibited target cell information, handover will be prohibited (step 1260) and handover will be terminated (step 1265). However, the first prohibited target cell information which is queried in circumstances where the device is a priority device is likely to have fewer prohibited base stations. Accordingly, a priority device is more likely to not be prohibited, at step 1260, from proceeding with the handover, such that the handover would proceed at step 1270.

Cellular telecommunications networks are increasingly used for the transmission of data. Where priority users use a general access logical mobile telecommunications network, it would be advantageous for the data traffic of those priority users to be prioritised over data traffic of non-priority users. More particularly, it would be advantageous to provide those priority users with a data rate or bandwidth that is always greater than a threshold (minimum) data rate. In this way, priority users can be guaranteed a minimum bandwidth, even though they are using a general access logical mobile telecommunications network, and not a dedicated logical mobile telecommunications network.

Accordingly, in embodiments the mobile telecommunications network infrastructure allocates resources to a priority device in preference to allocating those resources to non priority devices. The resources allocated to the priority device should be sufficient to enable the device to communicate data at a rate greater than a threshold data rate.

The allocation of radio access network resources may be the function of a component of the base station known as the "scheduler". The scheduler schedules uplink and downlink transmissions, and determines the radio frequency spectrum used for those transmissions. The timing and frequency of uplink and downlink transmissions is communicated to user devices. Accordingly, the scheduler may be configured to ensure that priority devices are provided with resources to communicate data at a rate greater than a threshold data rate.

Data communication in modern cellular telecommunications networks takes place over one or more data bearers. In such embodiments, an identifier may be associated with each bearer, and this identifier may be used to prioritise the bearers.

In standards-based LTE networks, each bearer is associated with a QoS Class Indicator (QCI). The eNodeB associates a priority with each QCI, which informs the scheduler (which is part of the eNodeB) which data should be given priority. Data in higher priority bearers should be given priority over lower priority bearers.

When a bearer is established, its QCI is also determined. The Quality of Service (QoS) attributes that form part of the QCI may be partly determined by the eNodeB, and may partly be communicated to the eNodeB from an MME. Where the QCI (or QoS parameters) of a bearer is communicated to the base station by an MME, this communication may be in the form of a message, such as an InitialContextSetupRequest message. Similarly, the QCI of a bearer may be communicated to a device in messages, when the bearer is established. Those messages may be Activate Default Bearer Request messages or Activate Dedicated Bearer Request messages (in standards based LTE networks).

Once the QCIs have been associated with the bearers, the scheduler can assign a priority to each bearer. Each bearer may also be associated with a minimum bitrate. Bearers used by priority devices may have a minimum bitrate equivalent to the threshold data rate. The scheduler is then able to monitor the bitrate of each bearer, and allocate more spectrum or schedule transmissions more often if the bitrate of the bearer falls below the threshold data rate.

An exemplary process that may be undertaken by the mobile telecommunications network infrastructure to allocate resources to a priority device in preference to allocating those resources to one or more non-priority devices will now be described with reference to Figure 13.

When allocating resources, the mobile telecommunications network infrastructure (for example, an eNodeB) may decide which UE should be provided the most resources. In one embodiment, the eNodeB does this by first measuring the bitrate of the bearer allocated to each UE to ensure that the bearer meets the minimum bitrate required for that UE (step 1302), i.e., a minimum bitrate guaranteed by the telecommunication service provider to be provided to that UE. If the bearer is meeting its promised bitrate (that is, the associated UE is able to communicate data using the mobile telecommunications network infrastructure at a rate greater than a threshold data rate), the bearer is added to the 'normal' list at step 1304. However, if the bearer is not meeting its promised bitrate, the bearer is added to the 'Elevated' list at step 1306. The bearers in the Elevated list are then ordered with respect to the priority associated with their QCI at step 1308. Once all bearers have been allocated to either the 'Elevated' or 'Normal' list and the Elevated list sorted according to priority, the eNodeB will allocate resources to the bearers in the 'Elevated' list in the sorted order (step 1310) until all resources are exhausted. If there are any remaining resources after scheduling the bearers in the 'Elevated' list (step 1312) then the remaining resources are allocated to bearers in the 'Normal' list (step 1314). If no resources are remaining the same procedure is repeated at the next scheduling occasion.

Priority devices may be promised a threshold data rate, while non-priority devices may not be promised a data rate (or promised a 0 data rate). In such circumstances, priority devices will be allocated resources in preference to non-priority devices, and the resources allocated to the priority devices will be sufficient to enable the device to communicate data using the mobile telecommunications network infrastructure at a rate greater than the threshold data rate.

As described above, devices associated with priority user accounts (priority devices) are associated with bearers having QCIs which are given higher priority by the scheduler at the base station (an eNodeB in an LTE-based network). The association of priority devices with higher priority bearers may occur irrespective of the logical mobile telecommunications network to which the device is connected. This means that priority devices are allocated sufficient resources to enable the devices to communicate data at a rate greater than a threshold data rate, and this occurs regardless of whether the device is communicating over a dedicated logical mobile telecommunications network, or a general access logical mobile telecommunications network. There may be circumstances where priority users use a general access logical mobile telecommunications network (for example, where any dedicated logical mobile telecommunications networks are congested), and in such circumstances, it is desirable for priority users to be able to rely on having bandwidth greater than a minimum bandwidth.

Where a priority device attaches to a general access logical mobile telecommunications network, they will be allocated a bearer having a high priority QCI in a process similar to that which occurs when the priority device attaches to a dedicated logical mobile telecommunicationsnetwork.

Where a priority device is handed over between a dedicated logical mobile telecommunications network and a general access logical mobile telecommunications network, the handover process ensures that the attributes of the bearers are also preserved throughout the handover process. The configuration in each base station or eNodeB may need to also ensure that the bitrate thresholds are preserved during handover (these thresholds being the result of a QCI to minimum bitrate mapping). Handover between a dedicated logical mobile telecommunications network and a general access logical telecommunications network may be simplified if the logical two mobile telecommunications networks share a common core network.

Adopting such a handover ensures that priority devices that are allocated sufficient resources in one logical telecommunications network to enable the device to communicate data at a rate greater than a threshold rate are also able, in other logical mobile telecommunications networks, to communicate data at a rate greater than the threshold rate.

Where, as described above, a priority device uses a general access logical mobile telecommunications network, it is desirable for that device to have priority service. This may involve the scheduling of radio resources as described above. In circumstances where the general access logical mobile network is congested (or nearing congestion), it may be desirable to ensure that new priority users are able to join the general access logical mobile telecommunications network in preference to non-priority users.

A device attempting to access cellular mobile network infrastructure may be denied access if the base station to which access is being sought considers itself to be "full", that is, it may not have sufficient resources to provide adequate quality of service. In such circumstances, the device may re-attempt to gain access, in case some resources have become available (for example, because a device that had been previously connected has been handed over to an adjacent cell). The device may make multiple attempts at gaining access. This may have the effect of overloading the base station, or denying access to another device that is also attempting to gain access. If the retrying device is a non-priority device, multiple retries at gaining access in quick succession may have the effect of denying access to a priority device.

In embodiments, the base station can control the rate at which devices seek access to its resources. It does this by means of broadcast access instruction messages, which can control whether devices seek access to the base station, and if unsuccessful, the "back-off algorithm" used by the devices. That is, the messages cause at least some devices which receive it and which are not associated with a priority user account to reduce the rate at which they seek access to the telecommunications network infrastructure. Any suitable barring or back-off algorithm may be used, which involves a controlling parameter that may be included in a broadcast message. In preferred embodiments, the broadcast messages include a threshold. Devices which seek access to the base station generate a random number within a predefined range, and compare that number to the threshold within the broadcast message. If the random number is lower than the threshold number, the device attempts access. However, if the randomly generated number is higher than the threshold, the device waits for a period of time before re-generating a random number and repeating the process above. Only when the randomly generated number is less than the threshold can the device seek access to the base station.

Accordingly, if a base station is fairly congested, it may lower the threshold within its broadcast messages. This will result in fewer devices generating numbers lower than the threshold, and in turn will reduce the rate at which devices seek access to the base station.

The amount of time that a device must wait between randomly generating numbers may be determined by the device, or alternatively, may be a parameter included in the broadcast message. That is, the broadcast message may not only include the threshold, it may also include a waiting time.

In some embodiments, devices attempting to connect to the base station transmit to the base station an access message that includes access class information based on information on the physical or virtual Subscriber Information Module in the device. Based on the access class information the base station determines whether the access class information represents a priority access class, in which case the device is a priority device (that is, the user account which is associated with the SIM information belongs to a priority user).

The base station may then selectively allow devices of specific access classes to attempt to gain access to the base station without undertaking any barring or back-off procedures, such as the procedure described above. Such devices would be able to access the base station without limitation.

In some networks, the broadcast access instruction message that controls the access procedures undertaken by devices seeking access to the base station and causes at least some devices which receive it and are non-priority devices to reduce the rate at which they seek access to the telecommunications network infrastructure, or not seek access at all, may be in the form of a System Information Broadcast message, part of an example of which is shown as 1400 in Figure 14. Such a message may indicate whether the base station is using a form of access class discrimination or barring (1410), and may also include the threshold (which could be in the form of parameter ac-BarringFactor 1420) and a waiting time (which could be in the form of parameter ac-BarringTime 1430). A further parameter (such as a bit set in ac-BarringForSpecialAC 1440) may determine whether certain access classes are not barred and do not need to undertake the barring or back-off procedures. Where a System Information Broadcast message is used, the devices may generate a random number between 0 and 1, for comparison with ac-BarringFactor 1420. In the exemplary System Information Broadcast message of Figure 14, the ac BarringFactor 1420 is "p95". Devices generate a random number between 0 and 1, and if that number is less than 0.95, an attempt is made to access the base station. However, if that random number is greater than or equal to 0.95, access is not attempted. In this example, "p95" indicates that 95 percent of users are permitted to attempt access. Similarly, an ac-BarringFactor of 1 (i.e., p100) means 100% of users are permitted to attempt access.

As described above, the mobile telecommunications network infrastructure can restrict the number of devices attempting to seek access to it, and reduce the rate that any permitted devices seek access to it. An exemplary behaviour of the device in this circumstance and on an LTE-based network will now be described with reference to Figure 15.

After successfully attaching to the network (for example, by using the ATTACH procedure as further described above with reference to Figure 3) the UE reads the broadcast System Information messages (such as the SIB of Figure 14) to determine barring attributes (including the acBarringFactor, which is a number between 0 and 1, representing the percentage of users barred) at step 1502. If the UE determines that it needs to access the network (step 1504), the UE checks the Access Class (AC) provisioned on its SIM (step

1506). If the AC is between 11 and 15, the UE is associated with a priority user (that is, the UE is a priority device) and is permitted to attempt an RRC Connection procedure at Step 1516 (see Figure 15). However, if the AC is less than 11, the UE is a non-priority device, and must choose a number between 0 and 1 at random (step 1508). At step 1510, the UE checks if the random number is less than the acBarringFactor (step 1510). If the random number is less than the acBarringFactor, the UE is permitted to begin the RRC connection procedure (step 1514). However, if, at step 1510, the random number is greater than or equal to the acBarringFactor, the UE must wait for a period of time (acBarringTime) (step 1512) before choosing another number between 0 and 1 at random (step 1508).

By configuring priority devices to have an Access Class that is different from non-priority devices, and by using broadcast messages with appropriate parameters, as described above priority devices can obtain priority access to telecommunications network infrastructure. Such access is particularly useful when the relevant resource (such as the base station) is at or near capacity.

As described above, the base station may send a broadcast access instruction message (such as a System information Broadcast message) which causes at least some devices which receive it and are non-priority devices to either not seek access to the telecommunications network infrastructure, or reduce the rate at which they do so. A reduction in the rate at which non-priority devices seek access to the telecommunications network infrastructure may be achieved by decreasing the threshold in the broadcast access instruction message.

In some embodiments, a broadcast access instruction message in the form of a cease access instruction message is sent by the telecommunications network infrastructure when utilisation of resources within the telecommunications network infrastructure is greater than a congestion threshold. The cease access instruction message may be a System Information Broadcast message that contains information causing some devices to either not seek access to the telecommunications network infrastructure, or reduce the rate at which they seek access to the base station. Accordingly, in accordance with this embodiment, it may be that the base station continues to send System Information Broadcast messages as usual, but includes in those messages information which causes at least some receiving devices to either not seek access to the telecommunications network infrastructure or reduce the rate at which they do so, when the utilisation of resources within the telecommunications network infrastructure is greater than the congestion threshold. For example, in the System Information Broadcast message 1400 shown in Figure 14, the ac-BarringInfo parameters (including parameters 1410, 1420, 1430, and 1440) may be included when the congestion level of a base station is greater than a congestion threshold.

An exemplary method of determining whether the utilisation of resources within a telecommunications network infrastructure is greater than a congestion threshold involves measuring the failure rate of attempts to connect to the network (for example, Radio Resource Control connection attempts). The higher the failure rate of such attempts, the greater the resource utilisation. If the failure rate of connection attempts is greater than a congestion threshold (which may be a parameter stored in the eNodeB), this acts as a trigger for sending a cease access instruction message as described above.

An example of such process undertaken by LTE-based mobile telecommunications network infrastructure will now be described with reference to Figure 16.

At step 1602, the eNodeB checks whether the RRC Failure Rate is greater than a threshold, indicating that the eNodeB is congested. If the RRC Failure Rate is greater than the threshold, at step 1604 the eNodeB decreases the ACBarringFactor included in its System Information Broadcasts, which has the effect of decreasing the percentage of traffic permitted to use that eNodeB. The eNodeB then waits a period of time (step 1610) before again checking the RRC Failure Rate against a threshold.

However, if, at step 1602, the RRC Failure Rate is not greater than a threshold, at step 1606 the eNodeB checks whether the ACBarringFactor is less than 1. If it is less than 1, that means that a percentage of traffic is being unnecessarily barred, and so, at step 1608, the eNodeB increases the ACBarringFactor to increase the percentage of traffic permitted.

The eNodeB then waits a period of time (step 1610) before again checking the RRC Failure Rate against a threshold.

If, at step 1606, the ACBarringFactor is not less than 1 (i.e., it is equal to 1), then there is no percentage of traffic being barred and so no action is taken to adjust the ACBarringFactor. The eNodeB simply waits a period of time (step 1610) before again checking the RRC Failure Rate against a threshold.

As described above, the base station may treat priority devices differently from non priority devices (for example, by exempting priority devices from the back-off and barring processes described above when seeking initial access to telecommunications network infrastructure). To enable the telecommunications network infrastructure to determine whether a device is a priority device or a non-priority device, the access requests it receives from devices seeking access to the telecommunications network infrastructure may include priority information indicating whether the device is associated with a priority user account, i.e., whether the device is a priority device.

For example, where the access request relates to initial access to a base station of the telecommunications network, as described above, information stored on a physical or virtual SIM is sent to the base station to enable the telecommunications network infrastructure to determine the access class of the device making the request. This information is an example of information indicating whether the device is associated with a priority user account.

Where initial access to the base station is granted, the device will typically attempt to set up a control plane connection with the base station. This involves an exchange of Radio Resource Control (RRC) messages. One of those messages is an RRC connection request. This request may be considered an access request, and may contain priority information indicating whether the device is a priority device.

An example of part of such an RRC connection request is illustrated in Figure 17. The RRC connection request may contain a "cause code" 1710 which indicates the reason why the device wishes to establish a control plane connection with the base station. The cause code may be selected from a set of cause codes, each having different priorities, For example, the highest priority cause code could be "Emergency", the second highest priority cause code could be "High Priority Access", and the third highest priority cause code could be "Mobile Terminating Access".

Where a base station receives an RRC connection request containing a cause code of "High Priority Access", this indicates that the device which sent the RRC connection request is associated with a priority user account. (Only devices having a sufficiently high Access Class, recorded at a location accessible to the device, such as on a SIM, are capable of sending High Priority Access cause codes.)

Alternatively or in addition, an access request in the form of a bearer establishment request may include priority information in the form of a device identifier such as an IMSI which the core network may use to query a database that stores an association of device identifiers with user account information to determine whether the device seeking access is associated with a priority user account.

Once the core network determines whether the device is associated with a priority user account, it may send a bearer setup request to the base station (which, for LTE networks, is an eNode-B). The bearer setup request may contain information which reflects the fact that the device is a priority device. For example, the bearer setup request may include QCI and/or QoS information which would indicate that the device is a priority device. Such information could include Allocation and Retention Priority (ARP) information.

As described above, a device may seek access to different parts of a telecommunications network infrastructure (possibly at different communication layers). For example, a device may seek to communicate:

- with a base station to establish an initial connection - with a base station (such as an eNode-B) to establish a control plane connection - with the core network (using an eNode-B) to establish a user-plane bearer.

In one or more of these requests for access, the access request (the precise form of which will differ depending on the nature of the access requested) may include priority information indicating whether the device is a priority device. This priority information may take any form, including information derived from a physical or virtual SIM, information that is only able to be sent from priority devices (such as a specific cause code), and a device identifier which the mobile telecommunications network infrastructure may use to query a database which relates device identifiers with user account information.

Although the telecommunications network infrastructure may treat priority devices different from non-priority devices in a variety of ways, it may discriminate between priority devices and non-priority devices with respect to whether the devices gain access to the resources of the telecommunications network infrastructure. That is, upon receiving an access request (that includes priority information indicating whether the device is associated with a priority user account, i.e., whether the device is a priority device), the telecommunications infrastructure may determine whether to permit the device access to resources, the determination being dependent upon the priority information included in the access request. For example, a base station may choose to send a System Information Broadcast message with thresholds and waiting times that have the practical effect of preventing non-priority users access to the base station, in the manner described above. Where a device seeks to establish a control plane connection with the base station, the base station may only allow devices which send RRC connection requests having a High Priority Access cause code to establish a control plane connection, and may not respond to or reject RRC connection requests with any lower-priority cause codes. Similarly, a core network may only establish a user-plane bearer connection with devices that are identified as priority devices.

As described above, a base station can reject RRC connection requests from devices that do not send a High Priority Access cause code. This could be enforced if the eNodeB is experiencing congestion. An exemplary RRC Admission Control procedure in an LTE based network is now described with reference to Figure 18.

At step 1802, the UE has already completed the Access Barring procedure described in Figure 15 and begins the RRC connection procedure. At step 1804, the UE checks the Access Class (AC) stored on the SIM card to determine if it is between 11 and 15 (indicating that the UE is associated with a priority user, i.e., the UE is a priority device). If the AC is between 11 and 15, the UE, at step 1806, sends a RRCConnectionRequest with the 'highPriorityAccess' cause code. The highPriorityAccess cause code instructs the eNodeB to accept the RRCConnectionRequest even if the eNodeB is congested (step 1808).

However, if, at step 1804, the AC of the UE is less than 11, the UE, at step 1810, sends a RRCConnectionRequest with a cause code other than 'highPriorityAccess'. If, at step 1812, the eNodeB is congested, the eNodeB will reject the RRCConnectionRequest (step 1814). However, if, at step 1812, the eNodeB is not congested, the eNodeB will accept the RRCConnectionRequest (step 1816).

In some embodiments, where there is contention for network resources, not only can the telecommunications network infrastructure choose to selectively allow access to only priority devices, it may also choose to have a higher priority device "replace" a lower priority device. In other words, if an existing communications channel (a 'second' communications channel) having an associated priority (a 'second' priority) is being used by a device (a 'second' device), a first device that is associated with a subscriber account having a higher priority than the subscriber account associated with the second device may "replace" the second device. This occurs by the telecommunications infrastructure allocating resources to create a first communications channel for the first device from the resources used for the second communications channel. In this way, the first, higher priority device "takes over" the channel from the second, lower priority device. This pre emption may also occur where the priority of the first communication channel is higher than the priority of the second communications channel.

A communications channel, in this context, includes the resources required to enable communications. As discussed above, user-plane communication occurs over a bearer. Such bearers require mobile telecommunications network resources. In an LTE network, these resources may include physical resource blocks, scheduler resources and baseband resources. The resources that constitute a channel may be either statically or dynamically allocated.

A bearer is therefore associated with a set of resources, which can be dynamically managed or statically allocated. Each bearer can be allocated a priority. The priority can be derived from bearer attributes, such as QoS attributes. As discussed above, the QoS attributes of a bearer may be received from the core network, and may depend on whether or not the device is a priority device (that is, associated with a priority user account).

Where a request for a communication channel, such as a request for resources to create and maintain a bearer, is received, a part of the telecommunications network infrastructure (such as the base station or eNode-B) determines whether there are sufficient available resources to satisfy the request, and create the bearer. If there are sufficient available resources, the bearer is created as requested. However, if there are insufficient available resources, the bearer cannot be created without resources being made available.

To make resources available, a part of the telecommunications network infrastructure (such as the base station) can release a lower priority channel, or a channel associated with a lower priority device (such as a device that is not associated with a priority user account). Releasing the channel may involve tearing down the bearer, making the resources that were required to support the bearer available for re-use.

Accordingly, where a priority device requests the creation of a communication channel, such as a user-plane bearer, and a base station is so congested that it does not have sufficient available resources to create and maintain the bearer, the base station may tear down a bearer having a lower priority than the bearer being requested to be created. As described above, bearer priority may be derived from bearer attributes, including QoS attributes. Alternatively, rather than relying on bearer priority, the base station may tear down a bearer being used by a non-priority device (that is, a device that is not associated with a priority user account). Having released resources by tearing down a lower-priority bearer, or a bearer being used by a lower priority device, those resources can be allocated to create a communications channel (or bearer) for the requesting priority device.

Accordingly, priority devices are more likely to be able to communicate using the mobile telecommunications network because the telecommunications infrastructure allocates resources to create a first communications channel having a first priority for the first (priority) device. Even if the base station is congested with non-priority users, the first communications channel can be created from resources used for an existing second communications channel have a second priority for a second device, if either the first device is associated with a user account having a higher priority than the user account associated with the second device, or the first priority of the first communication channel is higher than the second priority of the second communications channel.

The priority of the communications channels or bearers can also be influenced by other channel parameters, such as Allocation and Retention Priority (ARP) attributes. In some networks, the ARP attribute is part of a QoS parameter, communicated from the core network to the base station during bearer setup. The ARP attribute may contain information elements including an admission priority element, a pre-emption capability (PCI) element and a pre-emption vulnerability (PVI) element. The PCI information element can assist in determining the extent to which the bearer can be created at the expense of the tearing-down of lower priority bearers. The PVI information element can assist in determining the extent to which the bearer can be torn down to release resources for the creation of a higher priority bearer.

An exemplary process for creating a first communications channel, in the form of a bearer in an LTE-based network, will now be described with reference to Figures 19A and 19B.

As shown in Figure 19A, a bearer may be created as part of attach or handover procedure. Where the device being attached or received is a priority device, the MME will instruct the eNodeB to create a high priority bearer (step 1902). When this occurs and the eNodeB is not in a congested state, the new priority bearer will be established for the priority user at step 1904. However, if the eNodeB is experiencing congestion it will first identify the cause of the congestion at step 1906 to determine what resources need to be released to allow for the admission of the new priority bearer. If the congestion is being caused by a lack of bearer resources, the eNodeB will find and pre-empt a lower priority bearer (that is, tear down the bearer to release its resources) and then create the new priority bearer from the released resources (step 1908). If the congestion is being caused by lack of connected user resources, the eNodeB will release a lower priority user to make way for the priority user (step 1910).

As shown in Figure 19B, where the device being attached or received is a non-priority device, the eNodeB will be instructed by the MME to create a normal priority bearer for a normal (non-priority) user (step 1912). When this occurs and the eNodeB is not in a congested state, the new priority bearer will be established for the normal user at step 1914. If the eNodeB is experiencing congestion, it will reject the new bearer creation request (step 1916) to ensure eNodeB does not become more congested and thereby causing a degradation of the experience of the already connected users.

In some circumstances, one logical mobile telecommunications network may be suffering from congestion, and another logical mobile telecommunications network may have capacity. For example, a dedicated logical mobile telecommunications network may have reached its capacity, and it could be desirable for some of the priority users using the dedicated logical mobile telecommunications network to be offloaded to a general access logical mobile telecommunications network. The standard of service provided to such priority users may be maintained by some of the techniques described above. For example, if the general access logical mobile telecommunications network is congested, the priority users will be admitted to the base station in preference to non-priority users, and will have bearers created and allocated to them, even if that involves the tearing-down of a bearer being used by a non-priority user.

Accordingly, the cellular mobile telecommunications network infrastructure may initiate handover of a device connected to the infrastructure from an originating logical mobile telecommunications network (such as a dedicated logical mobile telecommunications network) to a receiving a logical mobile telecommunications network to which the device is permitted to connect (such as a general access logical mobile telecommunications network). Aspects of a handover procedure are described above.

In some embodiments involving an LTE based network, an LTE base station may send a message to a device requesting that the device report any acceptable cells on a target frequency. Such a message may take the form of an RRCConnectionReconfiguration Message. In response, the device will search for a target base station communicating on the target frequency, and report to the serving base station the strength of the signal received from the target base station, and its identity. This report may take the form of an RRCMeasurementReport. If an appropriate target base station (being a part of the receiving logical mobile telecommunications network) has been located, the cellular mobile telecommunications network infrastructure (and more particularly, a base station of that infrastructure) may instruct the device to attach to the target base station as part of a handover process. These instructions may take the form of an RRCConnectionReconfiguration Message having a mobilityControllnfo information element. This information element may identify the PCI of the target base station, the carrier frequency and the bandwidth.

In accordance with such embodiments, the mobile telecommunications network infrastructure can control the load on its logical mobile telecommunications networks, to ensure that users, and particularly its priority users, are able to obtain appropriate resources and that the logical mobile telecommunications networks are not overly congested. It does so by triggering a handover from an originating base station (being a member of an originating logical mobile telecommunications network) to a target base station (being a member of a receiving logical mobile telecommunications network) to which the device is permitted to connect.

In some embodiments, the handover of a device from one logical mobile telecommunications network to another is initiated upon the resource utilisation of a node associated with the originating logical mobile telecommunications network reaching or exceeding an originating network utilisation threshold. For example, the resource utilisation on a base station associated with a dedicated logical mobile communications network may reach or exceed an originating network utilisation threshold. This is an indication that the base station is overloaded, and may not be able to satisfactorily meet the resource demands placed upon it. Accordingly when the resource utilisation reaches or exceeds this utilisation threshold, handover of the device from the dedicated logical mobile communications network to another logical mobile communications network (such as a general access logical mobile communications network) is initiated.

An exemplary method of determining the resource utilisation of a base station, and whether it has reached or exceeded an originating network utilisation threshold, is to consider the extent to which a request for a bearer can be satisfied by the base station. A request for a bearer may be admitted where there are sufficient available resources to create and maintain the bearer. Alternatively, it may be rejected where there are insufficient resources. However, as described above, where the requested bearer is for use by a priority device, the resources allocated to a lower-priority bearer or a bearer used by a non-priority device may be released for reuse to create and maintain the requested bearer.

In such circumstances, the user of the lower-priority bearer (or the non-priority user of a same-priority bearer) will lose their bearer as its resources will be released for reuse by the higher-priority bearer request. This will result in the connection for the non-priority user being terminated. As an alternative, the non-priority user may be handed over to a different, receiving logical mobile telecommunications network. In this manner, the non priority user maintains the bearer over which they were communicating, although connection to this bearer will be over the receiving logical mobile telecommunications network, and not the originating logical mobile telecommunications network.

In the embodiment described in the previous paragraph, the handover of the device from an originating logical mobile telecommunications network to a receiving logical mobile telecommunications network is triggered by the resource utilisation of a node associated with the originating logical mobile telecommunications network reaching or exceeding an originating network utilisation threshold (that is, the originating logical mobile telecommunications network is overly congested). However, other triggers may initiate handover from an originating logical mobile telecommunications network to a receiving logical mobile telecommunications network. For example, handover may be initiated where the resource utilisation of a node associated with the receiving logical mobile telecommunications network falls below a target network utilisation threshold. This situation may arise where priority users have been handed over to a general access logical mobile telecommunications network due to congestion on a dedicated logical mobile telecommunications network. When the resource utilisation of a node associated with the dedicated logical mobile telecommunications network drops below a target network utilisation threshold (that is, the dedicated logical mobile telecommunications network becomes a less busy), the priority users may be handed back to the dedicated logical mobile telecommunications network.

The handover of the device from an originating logical mobile telecommunications network to a receiving logical mobile telecommunications network may also be triggered by a combination of the resource utilisation of nodes associated with the originating logical mobile telecommunications network and the receiving logical mobile telecommunications network. For example, handover may be initiated upon the resource utilisation of a node associated with the originating logical mobile telecommunications network reaching or exceeding an originating network utilisation threshold, and the resource utilisation of a node associated with the receiving logical mobile telecommunications network falling below a target network utilisation threshold. That is, handover may only occur where the originating logical mobile telecommunications network is a sufficiently congested, and the receiving logical mobile telecommunications network has sufficient capacity.

Exemplary processes for load-triggered handover will now be described with reference to Figures 20 and 21.

Referring first to Figure 20, periodically the originating logical mobile telecommunications network (such as an eNodeB of a dedicated logical mobile telecommunications network) will measure its congestion level (step 2002). If the eNodeB is currently not congested, the eNodeB will wait for a predetermined period of time before measuring the congestion level again (step 2004). If the eNodeB is found to be congested in step 2002, the eNodeB will request that a percentage of connected devices measure other frequencies for cells that are acceptable handover targets (step 2006). Devices which have been asked to search for a neighbour in step 2006, but are unable to find any acceptable neighbours, are allowed to remain on their current serving cell (step 2010). On the other hand, if an asked device does identify an acceptable handover target, at step 2008 the eNodeB undertakes a number of checks to determine whether handover should occur. These checks include checking if the load of the reported handover target is below a target network utilisation threshold, or if the handover is not permitted due to the handover target being a member of a Handover Restriction List (as further described above). If handover is found to be permitted, the device is instructed to handover to the reported neighbour (step 2012). If the handover is not permitted, the device is allowed to remain on its current serving cell (step 2010)

Referring now to Figure 21, periodically the general access eNodeB will request that connected priority devices measure dedicated frequencies for cells that are potential handover targets (step 2102). If a priority device asked to search for a neighbour in step 2102 is unable to find any acceptable neighbours, that device is allowed to remain on its current serving cell (step 2104). However, if an acceptable neighbour is found, at step 2106 the eNodeB undertakes a number of checks to determine whether handover should occur. These checks include checking if the load of the reported neighbour is greater than a target network utilisation threshold, or if the handover is not permitted due to the handover target being a member of a Handover Restriction List. If handover is found to be permitted the device is instructed to handover to the reported neighbour (step 2108). If the handover is not permitted, the device is allowed to remain on its current serving cell (step 2104).

A device may be handed over from an originating logical mobile telecommunications network to a receiving logical telecommunications network while it is actively communicating using the mobile telecommunications network infrastructure, over a communication channel. To reduce the prospect of a break in the communications, the device may maintain its association with attributes of the communication channel during handover. This enables the device to continue to use the same communications channel when connected to the receiving logical mobile telecommunications network. By maintaining the communications channel during handover between logical mobile telecommunications networks, the use of the telecommunications network infrastructure is uninterrupted.

In one exemplary process, the mobile telecommunications network infrastructure will begin the preparation for handover by signalling to a network element of the receiving logical mobile telecommunications network attributes of the communication channel by which the device is communicating with the originating logical mobile telecommunications network. Exemplary channel attributes are described below. The network element of the receiving logical mobile telecommunications network may be a base station or eNodeB. The channel attributes are stored and processed in anticipation of handover. Once the receiving network element has prepared a channel context based on the information received from a node of the mobile telecommunications network infrastructure (for example, a network element of the core network such as a Mobility Management Entity), it may signal to the core network element that it is ready to take over the communications channel. The device is then requested by the originating logical mobile telecommunications network to connect to the receiving logical mobile telecommunications network. Because the communication channel attributes had already been sent to the receiving logical mobile telecommunications network (or more specifically, a node of that network such as a base station), those attributes can immediately be applied to the communication channel established with the receiving logical mobile telecommunications network. The change from the originating logical mobile telecommunications network to the receiving logical mobile telecommunications network does not affect, and is invisible to, higher layers (such as the applications layer) of the communications channel.

The attributes of the communication channel may include attributes associated with a user plane communications channel, and attributes associated with a control plane communication channel. For example, when a device is handed over from an originating logical mobile indications network to a receiving logical communications network, it may maintain an association with one or more of its network addresses (such as an Internet Protocol address). Such network addresses are attributes associated with a user plane communications channel. In addition or alternatively, the device may maintain an association with Quality of Service parameters, which are an example of attributes associated with a control plane communications channel. Other attributes include bearer identifiers, tunnel endpoint identifiers, and QoS attributes (including, for a guaranteed bit rate bearer, the uplink and downlink guaranteed bit rates and maximum bit rates)

Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method of managing utilisation of cellular mobile telecommunications network infrastructure, including: connecting to a device which stores or has access to network selection information identifying at least two different logical mobile telecommunications networks to which the device is permitted to connect, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure; transmitting to the device a priority list of radio frequencies, each frequency in the list being associated with a priority, the priorities in the list at least in part determining the order in which the device will use the respective associated frequencies during cell selection or reselection; and before attempting handover to a target cell of the device from a serving cell to which the device is connected, querying prohibited target cell information to determine whether handover to the target cell should be initiated, wherein the content of the network selection information, priority list and prohibited target cell information at least in part depends upon whether the device is associated with a priority user account.

2. A method as claim in claim 1, wherein the mobile telecommunications network infrastructure allocates resources to a device associated with a priority user account in preference to allocating those resources to one or more devices not associated with a priority user account, the resources allocated to the device associated with a priority user account being sufficient to enable the device to communicate data using the mobile telecommunications network infrastructure at a rate greater than a threshold data rate.

3. A method as claimed in claim 2, wherein the device associated with a priority user account is allocated sufficient resources to enable the device to communicate data at a rate greater than the threshold data rate irrespective of the logical mobile telecommunications network to which the device is connected.

4. A method as claimed in any of the preceding claims, further including the mobile telecommunications network infrastructure sending a broadcast access instruction message, the access instruction message causing at least some devices which receive it and which are not associated with a priority user account to either not seek access to the telecommunications network infrastructure, or reduce the rate at which they seek access to the telecommunications network infrastructure.

5. A method as claimed in claim 4, wherein the broadcast access instruction message is sent by the telecommunications network infrastructure when utilisation of resources within the telecommunications network infrastructure is greater than a congestion threshold.

6. A method as claimed in any one of the preceding claims wherein the telecommunications network infrastructure receives an access request from a device seeking access to the telecommunications network infrastructure, the access request including priority information indicating whether the device is associated with a priority user account.

7. A method as claimed in claim 6, wherein upon receiving an access request, the telecommunications infrastructure determines whether to permit the device to access its resources, the determination being dependent upon the priority information included in the access request.

8. A method as claimed in any one of the preceding claims, further including the telecommunications infrastructure allocating resources to create a first communications channel having a first priority for a first device from resources used for an existing second communications channel having a second priority for a second device if the first device is associated with a user account having a higher priority than the user account associated with the second device; or the first priority of the first communications channel is higher than the second priority of the second communications channel.

9. A method as claimed in any of the preceding claims, further including the cellular mobile telecommunications network infrastructure initiating handover of a device connected to the infrastructure from an originating logical mobile telecommunications network to a receiving logical mobile telecommunications network to which the device is permitted to connect.

10. A method as claimed in claim 9, wherein the handover is initiated upon the resource utilisation of a node associated with the originating logical mobile telecommunications network reaching or exceeding an originating network utilisation threshold.

11. A method as claimed in claim 9 wherein the handover is initiated upon the resource utilisation of a node associated with the receiving logical mobile telecommunications network falling below a target network utilisation threshold.

12. A method as claimed in claim 10 or 11 wherein the handover is initiated upon the resource utilisation of a node associated with the originating logical mobile telecommunications network reaching or exceeding an originating network utilisation threshold and the resource utilisation of a node associated with the receiving logical mobile telecommunications network falling below a target network utilisation threshold.

13. A method as claimed in any one of claims 9-12 wherein where the device is associated with communication channel attributes in the originating logical mobile telecommunications network, the device maintains an association with the communication channel attributes during handover to the receiving logical mobile telecommunications network, thereby enabling the device to use a communications channel having the communication channel attributes when connected to the receiving logical mobile telecommunications network.

14. A method as claimed is claim 13, wherein the communication channel attributes include attributes associated with a user plane communications channel.

15. A method as claimed in claim 14, wherein the communication channel attributes include an Internet Protocol address.

16. A method as claimed in any one of claims 13 to 15, wherein the communication channel attributes include attributes associated with a control plane communications channel.

17. A method as claimed in claim 16, wherein the communication channel attributes include attributes associated with Quality of Service parameters.

18. One or more components of a mobile telecommunications network infrastructure configured to execute any of the methods claimed in any one of the preceding claims.

19. A cellular mobile telecommunications network infrastructure configured to: connect to a device which stores or has access to network selection information identifying at least two different logical mobile telecommunications networks to which the device is permitted to connect, each of the at least two different logical mobile telecommunications networks being accessible by use of the mobile telecommunications network infrastructure; transmit to the device a priority list of radio frequencies, each frequency in the list being associated with a priority, the priorities in the list at least in part determining the order in which the device will use the respective associated frequencies during cell selection or reselection; and after commencement of an attempted handover to a target cell of the device from a serving cell to which the device is connected, query the prohibited target cell information to determine whether handover to the target cell should proceed, wherein the content of the network selection information, priority list and prohibited target cell information at least in part depends upon whether the device is associated with a priority user account.