GB2447434A

GB2447434A - Restricting access to telecommunications networks based upon network conditions

Info

Publication number: GB2447434A
Application number: GB0702558A
Authority: GB
Inventors: David Fox; Gavin Wong; John M Watson
Original assignee: Vodafone Group PLC
Current assignee: Vodafone Group PLC
Priority date: 2007-02-09
Filing date: 2007-02-09
Publication date: 2008-09-17
Also published as: US20100197294A1; US8543112B2; CN101669389B; GB0818496D0; GB2450060B; GB0802482D0; GB0802479D0; EP2123082B1; WO2008096162A1; EP2123082A1; GB2450060A; GB0702558D0; CN101669389A

Abstract

Communication setup messages are filtered by network elements, such as base stations 3-5, 7A-9 and MSCs 2, 6, to restrict access to a mobile telecommunications network 12 based upon network conditions, i.e. to prevent congestion. In particular, low data messages, such as SMS, may be filtered from more demanding services, such as voice calls, so that all low data messages are transmitted, while the more demanding services are terminated, unless special conditions are met, e.g. a high priority level of an originating mobile terminal 1 and/or the intended recipient.

Description

1 2447434

IMPROVEMENTS IN THE IMPLEMENTATION OF

ThLECOMMUNICATIONS NETWORK ACCESS RESTRICTIONS This invention relates to a system and method for implementing access restrictions in a telecommunications network. More particularly, but not exclusively, this invention relates to a method of implementing access restrictions in a GSMJUMTSJLTE telecommunications network when the number of end users exceeds network capacity, such as in an emergency ui 11 31tuaIt)1.

Background

Currently in situations where the number of end users eKceeds network capacity, which may occur in emergency situations or for large public gatherings, such as sporting events or New Years Eve celebrations, the telecommunications network can quickly become congested. To allow high priority users, such as the emergency services, to get through, "Access Class Barring" is typically utilised. Access Class Barring is used to restrict public usage of the telecommunication resources.

To implement Access Class Barring, all mobile devices have a priority class, which is a numerical identifier associated with the mobile terminal's SIM card.

The SIMs used by high priority users each have a priority class of between 11 and 15, and the SIMs used by the public are allocated a priority class of between 0 and 9. The status of an additional Access Class 10, common to all priority classes, determines whether or not a particular mobile terminal (with or without a SIM card being present) may make an emergency call. The status is signalled over the air to the mobile terminal by the home or visited Public Land Mobile Network (PLMN). In the time of an emergency. access to the base stations in the problematic geographic region will be restricted by barring a number of classes of mobile terminals from using the network within that geographic region. This restriction could range from a full exclusion of the public, to only one or two public priority classes.

As the emergency services do not usually require all the network resources to be dedicated to them, it is typical that only a subset of the public classes are excluded from network access in the problematic cells at any one time. This is achieved by periodically cycling through all the public classes, for instance, classes 0 to 2 may be allowed network access for a period of time, and then classes 3 to 5 for a subsequent period of time and so on. It is important for the general public to have some ability to communicate in emergency situations, particularly since the inability to communicate can lead to greater levels of stress and panic, both on an individual basis and at a crowd level.

However, Access Class Barring is not an ideal solution for providing public access to the communication channels in the time of an emergency, particularly if the called party is in a restricted cell, as it is only the classes with access at any given time that are able to make receive calls. In other words, for a person-to-person communication to be established, and both parties are within a restricted cell, then both parties need to be of the classes that are allowed to access the network. For example, considering the situation of classes 1, 5 and 9 only being given network access in a restricted cell, if a person with a mobile terminal in class I wishes to call a person with a mobile terminal in class 8, and both terminals are within the restricted cell, then while the class 1 terminal will be able to initiate the call, the class 8 terminal will not respond to the call, as that terminal does not currently have network access. Overall, if half of all public terminals have been barred access to the network in a restricted access area, then the probability of two users being able to successfully establish a communication, when both terminals are within the restricted area, is only 25%.

It is also to be appreciated that another problem of' Access Class Barring is that when a communication cannot he established, it results in wasted signalling resources, as a terminal excluded from network access in a restricted cell will not respond to the incoming call, despite the effort that has gone into tracking the terminal down. This needless paging can also create further unnecessary congestion in the restricted cell.

Summary of the Invention

According to a first aspect, the present invention provides a method of restricting the establishment of communications in a mobile telecommunications network including: at least one network element, upon receiving a communication setupmessage, deciding whether to transmit the service request message based upon at least one network condition.

Preferably the at least one network condition includes: a type of service requested; a current load capacity of a base station; a priority level of a first mobile terminal device initiating a service request message; a priority level of an intended recipient of the communication setupmessage, where the intended recipient is a second mobile terminal device: and a paging area characteristic of the paging area of the second mobile terminal device.

The communication setup message may be a service request message transmitted by the mobile terminal seeking to initiate the communication, or a paging message generated from within in the network in response to the servicer request message.

Brief Description of the Figures

Figure 1 is a diagrammatic drawing of key elements of a mobile telecommunications network for use in explaining the operation of such a network, as well as the embodiments of the present invention.

Detailed Description of Embodiments of the Invention * Key elements of a mobile telecommunications network, and its operation, will now briefly be described with reference to Figure I. Each base station (BS) serves a respective cell of its cellular or mobile telecommunications network and receives calls from and transmits calls to a mobile terminal in that cell by wireless radio communication in one or both of the circuit switched or packet switched domains. Such a subscriber's mobile terminal (UE) is shown at I. The mobile terminal may be a handheld mobile t Irkgn c rcg-.n 1 r1 (T1 t 1 DF A I ririr c.ryri I*r r1, L%, t4 flI.at S.a. JJLJLnI I S.tI t/ JS t ÙIJIJFP *..%JI ÌJ4lL withadatacard.

In a GSM mobile telecommunications network, each base station includes a base transceiver station (BTS) and a base station controller (BSC). A BSC may control more than one BTS. The BTSs and BSCs comprise the radio access network.

In a UMTS mobile telecommunications network, each base station comprises a node B and a radio network controller (RNC). An RNC may control more than one node B. The node B's and RNC's comprise the radio access network.

In the proposed LTE mobile telecommunications network, each base station comprises an eNode B. The base stations are arranged in groups and each group of base stations is controlled by a Mobility Management Entity (MME) and a User Plane Entity (UPE).

Conventionally, in a GSM/UMTS network, the base stations are arranged in groups and each group of base stations is controlled by one mobile switching centre (MSC). such as MSC 2 for base stations 3. 4 and 5. As shown in Figure the network has another MSC 6, which is controlling a further three base stations 7, 8 and 9. In practice, the network will incorporate many more MSCs and base stations than shown in Figure I. The base stations 3. 4. 5. 7. 8 and 9 each have dedicated (not shared) connection to their MSC2 or MSC6 -typically a cable connection. This prevents transmission speeds being reduced due to congestion caused by other traffic.

The MSCs 2 and 6 support communications in the circuit switched domain -typically voice calls. Corresponding SGSNs 16 and 18 are provided to support communications in the packet switched domain -such as GPRS data transmissions. The SGSNs 16 and 18 function in an analogous way to the t''' .* I L' 1 Ii C C anti 0. i-ui tic SaKe UI Simpilcity, iuture reerericcs to an ivij._ iS also to be taken as equivalently covering an SGSN or an eNode B. Each subscriber to the network is provided with a smart card or SIM which, when associated with the user's mobile terminal identifies the subscriber to the network. The SIM card is pre-programmed with a unique identification IS number, the "International Mobile Subscriber Identity" (IMSI) and a priority class number between 0 and 15, where numbers 0 to 9 are allocated to SIMs for use by members of the public, and numbers 11 to 15 reserved for SIMs intended for special uses, such as for use by the emergency services. The status of an additional Access Class 10, common to all priority classes, determines whether or not a particular mobile terminal (with or without a SIM card being present) may make an emergency call. The status is signalled over the air to the mobile terminal by the home or visited PLMN. Neither of the IMSI or the priority number is visible on the card, nor does the subscriber know them. The subscriber is issued with a publicly known number, that is, the subscriber's telephone number, by means of which callers initiate calls to the subscriber.

This number is the MSISDN.

The network includes a home location register (1-{LR) 10 which, for each subscriber to the network, stores the IMSI and the corresponding MSISDN together with other subscriber data, such as the current or last known location of the subscriber's mobile terminal. This information is used when paging a mobile terminal.

Paging is a process of broadcasting a message, which alerts a specific mobile terminal to take some action -for example, to notify the terminal that there is an incoming call to be received. If the network knows in which cell the mobile terminal is located, it is only necessary to page in that cell. However, if the mobile terminal is moving within the network, the precise cell in which the L f...11 L IIIOU11 t1III1IIdI I 1UL4Lu iitay IIIJL 1)C ruitiwij. IL witi uiciciuic u Ui perform paging in a number of cells.

A first embodiment of the invention will now be described in relation to the identification of a situation where network congestion has occurred, or is likely to occur. In this the core network sends an instruction to all base stations/Node Bs and MSCs/MMEs in the restricted area, in order to implement a predefined "restricted access" mode. In "restricted access" mode, each base station and MSC has a set of rules that it must use to decide whether or not to forward a call setup/paging message in order to allow a communication attempt to proceed, whilst also providing full network access to the emergency services and the like.

With reference to Figure 1, to illustrate this embodiment of the invention, MSC 2 and base stations 3 and 4 are within the problematic area and are operating in the restricted access mode. In this regard, with network access restrictions in place, the behaviour of all base stations and MSCs in the restricted area is modified.

When a subscriber I in the restricted area wishes to make a call or send a message to another party. they will enter the number to be called, the message (for a data service) and press "send" or "call", as applicable. The mobile terminal I will then transmit a call setup service request to the nearest base * station/Node B 3, which in this embodiment is operating in "restricted access" mode.

The base station 3 will assess the caIIISMS setup information received from the mobile terminal 1 in order to determine if it should forward the request for further processing by the network. For example, the base station 3 will check the class of the terminal I sending the message. If the calling mobile terminal I has a class of between 11 and 15 (i.e. belonging to a high priority class), then th nioifla rprl,Jpt will h i cant rn ti ttt tiIVC) r * A*.sss. *SS 45 SSJ 525 A A If the calling mobile terminal I belongs to a member of the public (i.e. having a priority class of between 0 and 9), then the base station 3 may determine if the mobile terminal I is calling a high priority entity. For instance, if the mobile terminal I belongs to a member of the public, but is calling a high priority entity (Class 11-15), or is attempting to call a special emergency services number (such as 112 or 911), and access Class 10 is permitted, then the base station 3 can decide to forward the request.

If the party being called is just a member of the public, the base station 3 may also determine the type of communication requested, for example, whether the service request is intended to deliver an SMS or establish a voice communication. If the service request is for an SMS, in view of the low data rate required for this message, the base station 3 can decide to forward the message, regardless of who is sending or receiving the message.

If the service request is for a voice communication, however, the base station 3 may implement additional filtering steps. For example, the base station 3 will check its own current cell capacity, and determine if its capacity is sufficient to he able to sustain the communication, without adversely affecting the high priority users' ability to utilise the cell. To implement this, the restricted access" mode may provide the base station 3 with a cell capacity threshold. If the base station's cell is currently operating below the threshold, then the base station can decide to forward the paging request to the MSC 2, with a view to establishing the voice communication, regardless of the identity of the sender or the recipient. If, however, the base station's cell is operating above the threshold, it can reject the service request. In other words, the base station 3 will reject the service request where all of its resources available for public usage are already in use. Where this occurs, the attempt to establish a communication has been terminated without undue use of network resources, as the decision to reject the service request has occurred within the initial base station 3.

Where the initial base station 3 allows the service request, the request will be forwarded onto the appropriate MSC 2. Before the MSC 2 performs its usual functions to establish a call, such as authenticating the identity of the terminal 1, the MSC will perform its own checks in order to determine whether it should terminate the service request or continue to process it.

For instance, the MSC 2 will determine that the communication is a low data rate communication, like an SMS, and simply proceed with sending the request to the core network 12.

Where the MSC determines the communication required to be a voice communication, the MSC 2 will make a decision on whether or not to continue with the request for this more demanding service, such as based upon the size of the paging area of the intended recipient.

For each mobile terminal, the core network 12 will have a record of the terminal's last recorded position and one or more tracking areas/location areas/routing areas, associated with that last location. which will be the paging area for the recipient terminal. In regard to a UMTS/GSM network, the coverage area of the mobile telecommunications network is divided into a plurality of location areas (LAs) (for circuit switched communications) and into a plurality of routing areas (RAs) (for packet switched communications). The equivalent areas in the proposed LIE network are described as tracking areas (lAs). Typically, although not necessarily, a location area/tracking area/routing area is larger than the area of a single cell and within the area covered by a single MSC.

To make the decision whether or not to proceed with the call setup/SMS request, MSC 2 will retrieve paging area information for the intended recipient terminal either from its own VLR 14, or from the core network's HLR 10.

Once the MSC 2 has the recipient terminal's paging area information, the MSC will make a decision on whether or not to terminate the call by paging the mobile. For example, if the tracking area is too large and will use up too many signalling resources, then the MSC 2 will decide to terminate the call/SMS request. In this regard a size threshold can be used to determine if the tracking area is too large. The threshold will typically be based upon the number of cells in the tracking area.

The MSC 2 may also have additional information from the core network 12 in regard to the location of high congestion areas. The MSC 2 can therefore also decide to terminate the call establishment if the paging area is part of a high congestion area. For instance, the MSC may decide to terminate the call where the paging area includes congested cells. In this regard, each cell can have a status associated to it, which the MSC uses in making its decision.

If the MSC 2 decides that the call establishment will proceed, and MSC 2 controls the required paging area, such as the cell of base station 5. then MSC 2 will transmit the paging request to base station 5. If the paging area belongs to another MSC, such as the cells of base stations 8 and 9, controlled by base station 6. then MSC 2 will relay the call establishmentlSMS request to the * second MSC 6, via the core network 12. This second MSC 6 can then perform similar filtering as the first MSC 2, if required.

Similarly, the core network 12 can perform additional filtering, particularly in regard to information that would be burdensome to provide to each and every MSC in the network.

A final filtering stage may be performed by the one or more base stations (5 or -. -1 e, ) once wey ieceivc inc pdgillg icquesL. iustance, it LIIC paging Fequcst iS intended to establish a voice communication, and the base station has exceeded its public access threshold, the base station may decide not to proceed with broadcasting the paging request.

If the paging request is to be allowed, the base station will broadcast the request. Unlike Access Class Barring, when a UE receives a paging message, it will respond to the call in order to allow the communication to be established.

In this regard, the UE relies on the network to manage the network resources in a restricted access situation, rather than the UE having the responsibility for doing so, based upon its pre-set class priority.

Therefore from this embodiment it can be seen that the present invention can still attain the benefits of Access Class Barring, but is also able to provide greater flexibility in regard to how other communications are allowed or disallowed. Access Class Barring has limited functionality, since priority can only be given on a per base station or subscriber basis. The present invention.

however, allows network access to be controlled dependent on the network situation and priority needed.

In particular, the present invention is able to allow all users to transmit small bandwidth messages, such as SMS, rather than only some UEs being able to perform more demanding services with higher bandwidth requirements. ii

The embodiments described are to be considered as illustrations of the invention and not be limited thereto, as variations are possible. For example, the network can have a number of different levels of operating procedures for each of the base stations and MSCs that can be implemented depending on the situation. In other words, the network elements do not need to be all operating according to the same procedures -different procedures can be applied to each base station and MSC as required. For example, different capacity level thresholds can be applied to each base station.

Further, the filtering functionality need not be performed by each and every base station and MSC, as described above. Instead, the MSCs, for instance, may be excluded, so that only the base stations and the core network perform the filtering functionality. Alternatively, the MSC may perform the filtering for each of its base stations, so that no filtering is performed in the base station.

The key concept is that it is the network that controls the filtering functionality, so that the exact location of where the filtering is performed is not an essential element of the invention.

Although the embodiments described have generally been in relation to mobile-to-mobile communications, the embodiments of the invention equally apply to landline originating or landline terminating calls in relation to a single mobile terminal. The filtering functionality in this regard will only apply to the base station and MSC controlling the restricted cell where the mobile terminal is located, and possibly the core network.

It is also to be appreciated that the functionality just described is one example of a network in which the embodiments of the invention may be implemented.

For example, the functionality just described may also apply to the proposed LTE mobile telecommunications network. with its eNode Bs performing the * functionality of the base stations and the MME/UPE performing the functionality of the MSCs/VLRs.

Claims

I. A method of restricting the establishment of communications in a mobile telecommunications network including: at least one network element, upon receiving a communication setup message. deciding whether to transmit the communication setupmessage based upon at least one network condition.
2. The method of claim I wherein the at least one network condition includes: a type of service requested; a current load capacity of a base station; a priority level of a first mobile terminal device initiating the communication set up message, being a service request message; a priority level of an intended recipient of the communication setup message, where the intended recipient is a second mobile terminal device; and a paging area characteristic of the paging area of the second mobile terminal device.
3. The method of claim 1 or 2 wherein the at least one network element will transmit the communication setup message where the type of service requested is a low data rate service.
4. The method of any preceding claim wherein the at least one network element will transmit the communication setup message where the type of service requested is a Short Message Service (SMS).
5. The method of any preceding claim wherein the type of service requested is a voice communication and one of the at least one network elements will transmit the communication setup message where the current load capacity of the base station is below a predetermined load threshold.
6. The method of any preceding claim wherein the type of service requested is a voice communication and one of the at least one network element will not transmit the communication setup message where the current load capacity of the base station is above a predetermined load threshold.
7. The method of claim 5 or 6 wherein the communication setup message is a service request message, and the base station is the base station receiving the service request message directly from the first terminal device initiating the service request message.
8. The method of claim 5 or 6 wherein the communication setup message is a paging request message, and the base station is the base station broadcasting the paging request message in its cell.
9. The method of claim 7 or 8 wherein the network element is the base station.
10. The method of claim 7 or 8 wherein the network element is a Mobile Switching Centre (MSC) controlling the base station.
11. The method of any preceding claim wherein the network element will transmit the communication set up message where the priority level of the intended recipient of the communication setup message is a high priority entity.
12. The method of any preceding claim, wherein the network element will not transmit the communication setup message where the priority levels of the first terminal and the second terminal are not high priority levels, and the type of service requested is a voice communication.
13. The method of any preceding claim, wherein the communication setup message originates from a landline terminal, and the communication setup message is intended for the second mobile terminal device.
14. The method of any one of claims I to 11 wherein the communication setup message. which is a service request message, is transmitted by the first mobile terminal and is intended to establish a communication with a landline ternii n1
15. The method of any one preceding claim, wherein the paging area characteristic is the paging area size, and the network entity will terminate the communication setup message where the paging area size exceeds a paging area limit.
16. The method of any one preceding claim, wherein the paging area characteristic is the paging area congestion status, and the network entity will terminate the communication setup message where the paging area includes a congested cell.
17. A system configured to perform the method according to any one of claims Ito 15.