Improvements in and relating to an emergency service in a telecommunication system

Abstract

A method of operating a User Equipment, UE, wherein if the UE has an active timer, associated with requesting Disaster Roaming, DR, from a network, and the UE attempts to make an emergency call, then

Description

The present invention relates to the handling of an emergency communication in a telecommunication system. In particular, it relates to the handling of an emergency communication, such as a call to an emergency service (e.g. 911, 999 or 112) from a mobile telephone or User Equipment, UE, from a cellular telecommunication system during a time when an associated network is afflicted with a disaster situation. 3GPP working groups have developed solutions to enable a UE to get service even when a disaster condition (e.g. fire, etc) occurs on a Public Land Mobile Network, PLMN. In this case, the UE is said to obtain disaster roaming service on a forbidden PLMN when no other PLMN is available. In other words, the UE is permitted to temporarily register with a PLMN which would ordinarily be unavailable or forbidden, for a period including the declared disaster. The UE may start a timer, referred to as a disaster roaming wait range, which controls when the UE actually registers to the network to obtain so called disaster roaming service, see 3GPP TS 24.501. The disaster roaming wait range is intended to spread UE access to the target PLMN so as to avoid congestion. The following is described in 3GPP TS 24.501 about the wait range: “Upon selecting a PLMN for disaster roaming as specified in 3GPP TS 23.122: a) if the UE does not have a stored disaster roaming wait range, the UE shall perform a registration procedure for disaster roaming services on the selected PLMN as described in clause 5.5.1; and b) if the UE has a stored disaster roaming wait range, the UE shall generate a random number within the disaster roaming wait range and start a timer with the generated random number. While the timer is running, the UE shall not initiate registration on the selected PLMN. Upon expiration of the timer, the UE shall perform a registration procedure for disaster roaming services as described in clause 5.5.1 if still camped on the selected PLMN.” As can be seen, it is clearly stated that “While the timer is running, the UE shall not initiate registration on the selected PLMN”. However, a problem with such an arrangement is that the UE may have a request for emergency services, (which is a high priority service where delays may be extremely undesirable or even dangerous), when the wait timer is running and the procedure set out in the prior art, referred to above, does not enable access to emergency services. As such, the user will be placed in a highly undesirable situation where they will not be able to access emergency services. Such a delay us highly undesirable. The UE which is waiting to register for disaster roaming service which, by definition, would be with an otherwise forbidden PLMN, will be in a limited service state. The network normally broadcasts whether it accepts UEs in a limited state to obtain emergency services by performing an emergency registration. Assuming that the network does indicate that limited state UEs can indeed obtain emergency services, then the UE which needs to place an emergency call but has a running wait timer will not be able to do so due to the explicit requirement that while the timer is running, the UE shall not initiate registration on the selected PLMN (as set out above). This requirement can lead to problems, since the user expects to get emergency service, whereas the UE will not initiate the procedure, due to the wait timer, which is active and running. It is an aim of an embodiment of the present invention to address this issue and permit the user to gain access to emergency services in such a scenario. According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. According to a first aspect of the present invention, there is provided a method of operating a User Equipment, UE, wherein if the UE has an active timer, associated with requesting Disaster Roaming, DR, from a network, and the UE attempts to make an emergency call, then the UE registers for emergency services. In an embodiment, registering for emergency services includes registering to use or establishing a Protocol Data Unit, PDU, session for emergency services. In an embodiment, the UE maintains the active timer, even after registering for emergency services. In an embodiment, if the active timer expires while the UE has an active emergency call or a Protocol Data Unit, PDU, session for emergency services, then the UE performs a registration procedure for DR, after the emergency call or the PDU session ends. In an embodiment, the timer is started with a random number and is arranged to prevent congestion on the network. According to a second aspect of the present invention, there is provided apparatus arranged to perform the method of the first aspect. In an embodiment, the apparatus of claim 6 comprises a UE. Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figure 1 shows a flowchart illustrating an embodiment of the present invention. In an embodiment, a UE with a running wait time should attempt to register when there is a need to use an emergency PDU session. Note that the following details apply for the case when the UE has received broadcast or system information indicating that the cell or PLMN supports emergency services, or IP Multimedia Core Network. Subsystem, IMS, emergency services, or Protocol Data Unit, PDU, session for emergency services, or eCall, optionally for a UE in limited service state (e.g. in 5GMM-REGISTERED.LIMITED-SERVICE or in state 5GMM-DEREGISTERED.LIMITED-SERVICE state). When a UE with a running timer, which was started with a generated random number within the disaster roaming wait range, needs to request emergency services, or needs to use / establish a PDU session for emergency services, then the UE initiates a registration procedure for emergency services i.e. the UE sends a Registration Request with the 5GS registration type Information Element, IE, set to "emergency registration". Furthermore, the UE keeps the timer running (i.e. the disaster roaming wait range timer). In other words, if the UE has a running timer which was started with a generated random number within the disaster roaming wait range (or if the timer is running), and / or the UE needs to establish a PDU session for emergency services, then the UE initiates the registration procedure and sets the 5GS registration type IE to "emergency registration" in the REGISTRATION REQUEST message. The UE keeps the timer running (or the UE does not stop the timer). Optionally, the UE behaves as described above after having selected a PLMN for disaster roaming as specified in 3GPP TS 23.122. When the UE registers for emergency service and establishes a PDU session for emergency service, the timer (which was started with a generated random number within the disaster roaming wait range) may expire while the UE’s PDU session for emergency services is still active. When this happens, the UE may behave in any of the following ways: 1. the UE may perform a registration procedure with the same PLMN, where the registration is for disaster roaming service. In this case, the UE sets the 5GS registration type IE to "disaster roaming mobility registration updating", or to "disaster roaming initial registration", in the REGISTRATION REQUEST message. This may be performed while the PDU session for emergency service is still active (i.e. while it has not been released) 2. the UE may perform a registration procedure for disaster roaming only after it finishes the emergency service, or only after the emergency service ends e.g. after the PDU session for emergency service is released. In one option, the UE may perform a registration procedure for disaster roaming when it deregisters from the network, where for example the UE deregisters after the PDU session for emergency service is released a. In this alternative, the UE may set the 5GS registration type IE to "disaster roaming mobility registration updating", or to "disaster roaming initial registration", in the REGISTRATION REQUEST message. Note: the UE behaves as described above when the UE is in 5GMM-CONNECTED mode, or 5GMM-CONNECTED mode with RRC inactive indication, or in 5GMM-IDLE mode. Further, if the UE registers for emergency services and completes the emergency service before the timer expires, the UE maintains the timer (i.e. the UE keeps the timer running) until it expires and then the UE registers for disaster roaming service. The procedures set out above may be applied in any order and in any combination. The following is an example text that may be proposed for 3GPP TS 24.501 standard specification, in accordance with an embodiment of the invention described herein: “Upon selecting a PLMN for disaster roaming, if: a) the timer is running as describe above; and b) the UE needs to request a PDU session for emergency services; the UE shall initiate the registration procedure and set the 5GS registration type IE to "emergency registration" in the REGISTRATION REQUEST message. The UE keeps the timer running. If the timer expires while the UE is registered for emergency services, the UE shall perform the registration procedure and set the 5GS registration type IE to "disaster roaming mobility registration updating" in the REGISTRATION REQUEST message.”. In an alternative embodiment, the UE may make an exception to the prior art requirement and perform a registration procedure for disaster roaming service even when the timer is running. As such, in this embodiment, the UE initiates the registration procedure and sets the 5GS registration type IE to "disaster roaming mobility registration updating", or to "disaster roaming initial registration", in the REGISTRATION REQUEST message. The UE may stop the timer after it has successfully registered in this case. For completeness, Figure 1 shows a representation of a method according to an embodiment of the invention. At S101, the UE begins a timer. The timer is to stagger DR requests in the event that a plurality of UEs attempt to register with another (non-home) network in the event of a disaster affecting the home network. At S102, with the timer running, the UE attempts an emergency call (including an emergency PDU session). At S103, the UE maintains the timer. According to an embodiment of the invention, a UE is able to place an emergency call even while a timer for staggering / delaying access to a network offering DR is running. This ensures that an emergency call can be placed in circumstances where the prior art might have prohibited this or otherwise adversely affected it. At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, 5 or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of operating a User Equipment, UE, wherein if the UE has an active timer associated with a Disaster Roaming, DR, wait range, for requesting DR from a network, and the UE attempts to make an emergency call, then the UE registers for emergency services on 5 the network associated with the request for DR, wherein if the active timer expires while the UE has an active emergency call or a Protocol Data Unit, PDU, session for emergency services, then the UE performs a registration procedure for DR, after the emergency call or the PDU session ends.

2. The method of claim 1 wherein registering for emergency services includes registering10 to use or establishing a Protocol Data Unit, PDU, session for emergency services.

3. The method of claim 1 or 2 wherein the UE maintains the active timer, even after registering for emergency services.

4. The method of any preceding claim wherein the timer is started with a random number and is arranged to prevent congestion on the network.15 5. Apparatus arranged to perform the method of any preceding claim.

6. The apparatus of claim 6 comprising a UE.

Images