WO2013137629A1

WO2013137629A1 - Method and system for selective access control with ensured service continuity guarantees

Info

Publication number: WO2013137629A1
Application number: PCT/KR2013/001991
Authority: WO
Inventors: Satish Nanjunda Swamy Jamadagni; Rajavelsamy Rajadurai
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2012-03-12
Filing date: 2013-03-12
Publication date: 2013-09-19
Anticipated expiration: 2014-09-12
Also published as: CN104186012A; CN104186012B; US20150055447A1; EP2826309A1; EP2826309A4; EP2826309B1; AU2013232943A2; AU2013232943A1; ES2843485T3; AU2013232943B2; US10219207B2

Abstract

A method and system for providing a continued service to user equipment (UE) under overload conditions is disclosed. A primary network undertakes a protective measure under unable to serve conditions by commanding a change in the UE network access behavior so that the UE can move to the secondary PLMN. After receiving the indication from the primary network, the UE connects to the secondary network and continues to obtain the services from the secondary network. The secondary PLMN ID can be sent to the UE in system information. Further, the information like overload indication, secondary PLMN ID and the time for which the UE can obtain the services from the secondary PLMN ID can be sent to individual UEs over dedicated messages either on an Access Stratum (AS) message or over a Non Access Stratum (NAS) message.

Description

METHOD AND SYSTEM FOR SELECTIVE ACCESS CONTROL WITH ENSURED SERVICE CONTINUITY GUARANTEES

The present invention relates to cellular networks, and more particularly relates to a method and system for providing continued service to user devices under unable to serve conditions.

Machine Type Communication (MTC) devices (sometimes referred to as Machine-to-Machine or M2M devices) are increasingly being used for a variety of applications. Their numbers are expected to grow at a high rate. MTC devices are typically automated data reporting systems such as utility meters or status reporting devices. MTC devices can be standalone devices serving one application: for example smart metering devices or can be regular cellular network User Equipments (UE) with MTC applications.

The MTC applications are likely to have significantly different usage or operational characteristics from other types of User Equipment (UE) applications. Such devices may be programmed to send data at a specific time, for example late at night. Also, other types of MTC devices may be triggered by specific events, such as a burglar alarm. Many of these may activated by the same event (for example, a power cut or earthquake). In any event, the volume of data transmitted and received by such devices is often low.

It has conventionally been understood that nearly all MTC devices (or at least 95%) will operate on their home cellular radio network, referred to as the Home Public Land Mobile Network (HPLMN). This is identified by the PLMN-ID of their International Mobile Subscriber Identity (IMSI). It has therefore been thought that network operators would be able to manage the large number of MTC devices by dimensioning their networks accordingly. Hence, MTC devices are generally expected to act and to be treated no differently from any other type of UE. In some critical network error conditions, where the HPLMN is unable to serve some particular device, then the network enables access barring and makes the UE to try after some time, by providing back-off timer values. From a UE perspective, since the HPLMN is available, the UEs will keep on trying to attach with the HPLMN. This access barring mechanism will make the UE to keep trying access attempts in the HPLMN and this will drain the device battery power faster. Also if the network enabled the access barring due to overload condition, this frequent attempts from the barred UEs will further make the network overload and consumes the network resources unnecessarily, as the network is not sure when it can recover from such unable to serve condition. It has to be understood that with the existing Access Class Barring/ Extended Access Barring (ACB/EAB) mechanism wireless devices like the MTC devices can get into no service scenarios and this amounts to non-service availability which has regulatory and legal implications as users are promised service by an operator. Operators want to avoid this situation and are therefore looking at an appropriate technical solution.

An appropriate solution mechanism was so far not possible as operators did not want to let another operator to serve their subscribers within a particular service area and technically the PLMN selection hierarchy was so designed to avoid any attachment of a UE to a not intended operator network. Also, as the PLMN selection mechanism was preprogrammed or prelisted into a Subscriber Identity Module (SIM), any drastic PLMN selection changes was not possible. In the current mechanisms, networks do not have the option to make the UEs to try to attach other network immediately or try to attach the same PLMN with different radio access technology, if the highest priority PLMN (like HPLMN) is available. Going forward it is also possible that network operators will implement dynamic spectrum sharing or dynamic inter operator policies and when such policies are implemented and network operator may use such additional spectrum or additional rights to offload to other operators when there exists no mechanism to offload users to such additional spectrum or make use of such additional rights for possibly offloading to other operator networks dynamically based on the said operator network conditions and policies.

The introduction of a large number of MTC devices leads to overload conditions in Long Term Evolution (LTE) networks. Such overload scenarios could lead to severe network failure and service disruptions. Recently 3GPP has started discussing over load issues in LTE network due to the introduction of a large number of MTC devices. Also typically the network operators face two types of overload namely, Core network overload and Access network overload. The Core network overload can be independent of the access network overload. Commonly such overload condition in LTE networks leads to service disruption conditions for UEs or UEs tend to view this as severe network failure.

In an existing system, there exists an EAB mechanism to handle the issue of core network and access network overload, but this mechanism does not distinguish Access network overload and Core network overload. The EAB is similar to the ACB for the UEs. However, with the EAB or ACB mechanism if the core network is overloaded, the operator will invoke the EAB or ACB mechanism even though the radio access network (RAN) is not overloaded and the UEs will go in to wait time or back-off time. There is no way of using the services of another core network when the EAB or ACB is invoked by the network or the core network is unable to serve, even though an alternative core network could be a shared network or a roaming partner which can serve the UE.

Further, the mechanism of keeping the wireless devices into wait time will not serve all classes of devices. Some of the devices might require timely access guarantees and the EAB mechanism (extended wait time) might not guarantee access within the required time. There might, then be service disruption for MTC devices. In such cases enhancements or alternatives to the EAB mechanism is required for providing reliable access. Some wireless devices like the Low cost MTC devices might also be low on memory and might not have the capability to hold onto too much data when a network pushes the wireless device into an EAB/ACB mode. In such cases the devices might be forced to rewrite data on the old available data leading to loss of data.

Presently, with the extended access barring (EAB) mechanism or access class barring (ACB), the MTC devices or UEs are indicated about the non availability of service through indications in system information or through reject cause value in the reject messages. Such mechanism allows for time based barring of the MTC devices or UEs which leads to service disruption for these devices or in other words these devices perceive the network to be in a severe error condition leading to service disruption. This can cause unwanted delays for time critical MTC devices. Further, in the present scenario, there is no classical definition of what type applications are supported by the MTC devices. The applications can be latency tolerant application like smart meters or time critical applications like medical applications. Also currently the PLMN hierarchy provides a UE to go for next available PLMN in the hierarchy if a service from a PLMN is unavailable, instead the invocation of the EAB/ACB/reject mechanism will keep the UE in back-off mode and UE will keep re-attempting to access the network with the back-off timer value provided by the network, being increased after each attempt. This leads to long delays before a UE can come out of an EAB/ACB mechanism and access a network to transmit critical data. This current UE and network behavior mentioned in the specifications leads to unacceptable delays and leads to the UE perceiving severe network failure under the specified conditions. This is an unacceptable situation. Due to the above mentioned reasons, there is a need in the art to reestablish mechanisms to alter the UE behavior in order to support continued service for MTC or normal wireless devices when the network is unable to serve UEs under severe error conditions.

In the light of above discussion, it is desirable to have a method and system for providing continued services to a UE under severe network failure conditions like overload conditions. It is further desirable to have a method for indicating to a UE to invoke an alternate network access behavior instead of the existing UE behavior when an EAB/ACB is invoked by the network or under a severe network failure condition in the network. It has to be understood that a lack of such a service continuity solution for wireless devices is a serious regulatory issue and that this can affect the service experience of millions of devices which are getting added into the networks. Existing ACB/EAB mechanism becomes restrictive in their use as it was never conceived or designed with service continuity. This has been a failure on the part of the design community to address the issue of service continuity when handling the critical network error issues.

Further, an "unable to serve condition" in a network might not always indicate an error; other possible causes can be "better service available in another network" or "new spectrum becomes available to the operator" or "new inter operator policies becomes enabled" through which the operator now has the rights to use part of an other operators network resources and the current operator would then like to initiate an inter-operator offload to balance the network.

An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a mechanism for continued service to user equipment (UE) through a new alternate UE behavior when a network invokes either an EAB/ACB mechanism or when a network faces severe network failure conditions.

Another aspect of the present invention is to provide a mechanism for networks to indicate and invoke an alternative network selection behavior when the network invokes either an EAB/ACB mechanism or when a network faces severe network failure conditions.

Further another aspect of the present invention is to provide a mechanism for selective access control along with ensured service continuity guarantees.

In accordance with one aspect of the present invention, there is provided a method for providing continued services to a user equipment (UE) under unable to serve conditions in a communication network, wherein the method comprises receiving a network selection behavior change indication from a primary network for connecting to a secondary network immediately by the UE when the communication network is unable to serve the UE. Further the method comprises attempting to attach to the secondary network by the UE immediately, upon receiving the network selection behavior change indication from the primary network for obtaining the services.

In accordance with another aspect of the present invention, there is provided a communication network for providing services to a user equipment (UE) under unable to serve conditions, wherein the communication network is configured to provide an indication to the UE for executing a network selection behavior change, wherein the UE forgoes any invocation of back off timers and continued primary network access attempts. Further the communication network is configured to initiate an immediate connection attempt to a secondary network.

In accordance with further another aspect of the present invention, there is provided a user equipment (UE) for obtaining continued services from at least one primary network, secondary network under unable to serve conditions, wherein the UE comprises an integrated circuit. Further the integrated circuit comprises at least one processor, at least one memory. The memory comprises a computer program code within the integrated circuit. At least one memory and the computer program code with the at least one processor cause the UE to receive a network selection behavior change indication from the primary network for connecting to the secondary network immediately. Further the UE is configured to attempt to attach to the secondary network, upon receiving the network selection behavior change indication from the primary network for obtaining the services.

These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

FIG. 1 illustrates a general block diagram of a user equipment, according to embodiments as disclosed herein;

FIG. 2 illustrates a flow diagram explaining the various steps involved in providing service to the user equipment through inter-operator reselection, according to the embodiments as disclosed herein;

FIG. 3 illustrates a sequence diagram for indicating the user equipment with a unable to serve indication using system information block, according to the embodiments as disclosed herein;

FIG. 4 illustrates a sequence diagram for indicating the UE with a unable to serve error cause value using non access stratum (NAS) reject message based approach, according to the embodiments as disclosed herein;

FIG. 5 illustrates a sequence diagram for indicating the UE with network access or selection behavior change indication using access stratum (AS) reject message based approach, according to the embodiments as disclosed herein;

FIG. 6 illustrates a flow diagram for pre-configuration based approach for indicating the secondary PLMN to the UE, according to the embodiments as disclosed herein;

FIG. 7 illustrates a flow diagram explaining the process of providing service to the UE under unable to serve conditions, using NAS based approach, according to embodiments as disclosed herein; and

FIG. 8 illustrates a computing environment implementing the method and system for providing service to the user equipment under unable to serve conditions in a network.

The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The embodiments herein achieve a method and system for providing a continued service to user equipment (UE) under network unable to serve conditions. The network indicates a switch in the UE network selection behavior to achieve continued service for UEs when network is under "unable to serve" conditions. The network indicates a behavior change in the way a UE should select an alternative network when EAB/ACB is invoked or when the network indicates severe network failure to a UE. Upon receiving an indication for access behavior change, the UE will seek an alternate network or same PLMN but different RAT as indicated by the primary or the serving network. The primary or the serving network optionally indicates the presence of a secondary network to the UE in a given area. The primary network also optionally indicates a secondary public land mobile network ID (PLMN ID) to the UE. After receiving an unable to serve indication from the primary network, UE connects to the secondary network immediately and try to obtain the services from the secondary network instead of following a behavior of starting a back off timer and waiting on the primary or the serving network.

Further, the primary network or serving network also optionally indicates the time duration for which the UE is attached to the secondary network or after what time duration, the UE try for the primary or secondary network. The method of supporting the "non availability of service" indication or the network access behavior change to user equipment or a group of UE devices can be achieved by modifying the system information in an LTE network.

In an embodiment, the system information can carry one or more of the unable to serve indication optionally along with a secondary PLMN ID and the time for which the MTC device can obtain service on a secondary PLMN or the time after which the UE try attaching to the primary or serving network.

In an embodiment, the UE can be a mobile phone, a smart phone, a Machine Type Communication (MTC) device or the like.

Throughout the description, the terms UE and MTC device are used interchangeably.

Throughout the description, the terms E-UTRAN, eNB and base station are used interchangeably.

Through the description, the terms overload condition, service disruption, and severe network failure is used interchangeably.

Throughout the description, the terms network access behavior and network selection behavior is used interchangeably.

Referring now to the drawings, and more particularly to FIGS. 1 through 8, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.

FIG. 1 illustrates a general block diagram of user equipment, according to embodiments as disclosed herein. As depicted in the figure, the user equipment 100 comprises a communication interface module 101, a power module 102, a display module 103 and a timer module 104. The communication interface module 101 helps the UE to connect to the access network. The power module 102 holds the battery information and status of battery power in the user equipment 100. The battery information comprises the amount of charge that the device posses and the time period for which the user equipment 100 will be in operation and so on. The display module 103 of the user equipment 100 comprises of a user interface which can be a key pad or through any other means by which a user can input some data into the user equipment 100. The timer module 104 calculates the elapsed time provided by the primary network or home public land mobile network (HPLMN) and the UE attempts to access the primary network or HPLMN upon the expiry of the timer. The time period for which the UE should not try to attach with the primary PLMN is preconfigured in the UE or provided by the primary PLMN of the UE through a system information block (SIB) or Access Stratum (AS) message or Non Access Stratum (NAS) message.

In an embodiment, the primary network is the serving network of the UE. In another embodiment, the primary network is the UE selected network or attached network to obtain service. In further embodiment, the serving network can be the home PLMN of the UE.

In an embodiment, the secondary network is the next available highest priority PLMN in the PLMN selector list. In another embodiment, the secondary network is the PLMN ID communicated to the UE by the primary network. In a further embodiment, the secondary network being the primary network with different RAT (not the same PLMN+RAT of the current primary network).

In an embodiment, the PLMN selector list is the "Operator Controlled PLMN Selector list with access technology" in the UE. In another embodiment, the PLMN selector list is the "User Controlled PLMN Selector list with access technology" in the UE. "HPLMN selector with Access Technology", "Forbidden PLMNs", "Equivalent HPLMN".

In another embodiment, UE PLMN selector list is a separate list of the PLMN in priority order used by the UE when the primary network indicates "unable to serve" indication.

FIG. 2 illustrates a flow diagram explaining the various steps involved in providing service to the user equipment through inter-operator reselection, according to the embodiments as disclosed herein. As depicted in the flow diagram 200, initially the MTC device or the UE 100 selects (201) the available PLMN and obtains the system information. Upon obtaining the system information, UE 100 checks (202) whether the system information includes an "Extended Access Barring" or "Access Class Barring". If the UE determines that the system information has no access barring, then the UE 100 initiates (203) the network attach procedure with the selected PLMN. Further, if the UE 100 determines that the access restriction is provided in the system information, then UE 100 checks (204) for the secondary PLMN ID and the information related to the secondary PLMN ID within the system information block (SIB).

In an embodiment, the system information can carry one or more of the overload indication or the network access or selection behavior change indication, optionally secondary PLMN ID and optionally the time for which the UE 100 can obtain the services from the secondary PLMN ID or the time for which the UE 100 should not disturbed the primary network by initiating access procedures. In another embodiment, the time value for which the UE 100 should not disturbed the primary network by initiating access procedures is preconfigured in the UE 100.

The UE 100 obtains the secondary PLMN ID from the SIB and the UE initiates (205) the network attach procedure with the obtained PLMN ID.

In an embodiment, the information like non availability of service indication, secondary PLMN ID and the time for which the UE 100 can obtain the services from the secondary PLMN ID can be provided in the system information.

In an embodiment, the system information can carry one or more of the non availability of service indication, secondary PLMN ID and the time for which the UE 100 can obtain the services from the secondary PLMN ID.

In another embodiment, the information like unable to serve indication, optionally secondary PLMN ID and optionally the time for which the UE 100 can obtain the services from the secondary PLMN ID can be sent to individual UEs over dedicated messages either on an Access Stratum (AS) message or over a Non Access Stratum (NAS) message.

The various actions in flow diagram 200 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 2 may be omitted.

FIG. 3 illustrates a sequence diagram for indicating the user equipment with a unable to serve indication using system information block, according to the embodiments as disclosed herein. As depicted in the figure, in step 301, the access network (E-UTRAN 300) broadcasts the master information block (MIB) to the UE. Further, in step 303, the UE 100 also obtains the system information block type 1 (SIB1) from the E-UTRAN 300. In step 305, the access network 300 broadcasts the EAB along with the unable to serve indication, optionally secondary PLMN to the UE 100 in the system information, as shown in the figure.

In an embodiment, the E-UTRAN 300 broadcasts the System Information Block Type2 (SIB2) including the unable to serve indication and optionally secondary PLMN ID.

SIB2 is taken as an example in the above embodiment and the parts of the information can be provided in different system information chunks. This information can also be defined as a Information Element (IE) or the information can be sent separate system information.

SystemInformationBlockType2

The IE SystemInformationBlockType2 contains radio resource configuration information that is common for all UEs.

NOTE: UE timers and constants related to functionality for which parameters are provided in another SIB are included in the corresponding SIB.

Tables 1 and 2 below show information element of the SystemInformationBlockType2 according to an embodiment of the present invention.

Table 1

Table 2

Table 3 below shows field descriptions of the SystemInformationBlockType2 according to an embodiment of the present invention.

Table 3

In an embodiment, the secondary PLMN (S-PLMN) is configured in the USIM by the network (HPLMN) of the UE 100. The SIB2 from HPLMN informs the UE with EAB and an indication to access S-PLMN.

In one embodiment, the secondary PLMN is the next available highest priority PLMN in the PLMN order/selector list configured by the primary network.

Further, the S-PLMN can be per-configured in the USIM of the UE 100 and this S-PLMN is used for accessing secondary network. The S-PLMN configuration in the USIM or in the MTC device can be either pre-configured by the network (HPLMN) based on subscription through Over the Air (OTA) or Operation and Management (OAM) (OMA DM or (U) SIM OTA procedures) configuration by the network dynamically.

In an embodiment, the list of the preferred PLMN is rearranged or new list is created, based on the high priority PLMN (network) conditions dynamically. For example, if the primary network is the highest PLMN ID in the UE PLMN selector list and currently the network is under severe network failure, then the primary network can indicate the OAM to rearrange the operator preferred PLMN list, so that primary PLMN will be in the last or totally removed. Then OAM will rearrange the preferred list accordingly.

SystemInformationBlockType2

The IE SystemInformationBlockType2 contains radio resource configuration information that is common for all UEs.

Tables 4 and 5 below show information element of the SystemInformationBlockType2 according to another embodiment of the present invention.

Table 4

Table 5

Table 6 below shows field descriptions of the SystemInformationBlockType2 according to another embodiment of the present invention.

Table 6

In an embodiment, there can be separate SIB with the above parameters, which will inform EAB along with SPLMN to access or indicator to indicate the EAP devices to access the SPLMN.

Table 7 below shows information element of the SystemInformationBlockType1x according to an embodiment of the present invention.

Table 7

Table 8 below shows field descriptions of the SystemInformationBlockType1x according to an embodiment of the present invention.

Table 8

FIG. 4 illustrates a sequence diagram for indicating the UE with a unable to serve error cause value using non access stratum (NAS) reject message based approach, according to the embodiments as disclosed herein. The core network (HPLMN) 400 of the UE 100 optionally indicates the UE 100 with a timer for re-attempting the core network 400 and optional secondary PLMN, also for when said UE 100 is determined as a low priority access UE by the core network (HPLMN) using the NAS message.

In another embodiment, the timer value for which the UE 100 should not disturb the primary network by initiating NAS messages is preconfigured in the UE 100.

In an embodiment, the NAS reject messages being ATTACH REJECT message, TRACKING AREA UPDATE REJECT message, and a SERVICE REJECT message.

For mobile originated requests (services or updates), UEs may be configured for low access priority, if configured provide a low access priority indication to the core network 400 in NAS signaling. In step 401, when the UE 100 sends a (periodic) Tracking Area Update (TAU) request to the core network 400. The UE 100 may indicate a low priority indication in NAS signaling to the core network 400 through the TAU request. The core network (HPLMN) 400 receives the TAU request. The core network may be under unable to serve condition due to overload or network error conditions. Further, the core network (primary network) 400 undertakes a protective measure by commanding the UE 100 to move to a state where the UE 100 does not need to generate further signaling messages and move to the secondary PLMN immediately. In step 403, the NAS commanding being through a NAS reject message with "unable to serve" indication. On receiving the "unable to serve" error cause value, the UE will initiate PLMN selection procedure to attach with the secondary network.

In an embodiment, UE will be preconfigured with timer value, till this timer value elapses, the UE will not try to access the primary network.

In an embodiment, the core network can be Mobile Management Entity (MME), Serving Gateway (S-GW), PDN Gateway (P-GW) or enhanced NodeB or Radio network Controller or the like.

In an embodiment, the core network 400 allocates a timer value to the UE 100 for indicating the UE 100 to re-attempt to access the home PLMN (HPLMN) after expiration of the specified timer value.

In another embodiment, the UE 100 will not reattempt to access the Primary network and the RAT, but will try to access the Primary network through a different RAT.

FIG. 5 illustrates a sequence diagram for indicating the UE with network access or selection behavior change indication using access stratum (AS) reject message based approach, according to the embodiments as disclosed herein. As depicted in the sequence diagram, for mobile originated request in step 501, UEs may be configured for low access priority, if configured then, provide a low access priority indication to the E-UTRAN 300 (Access network) in Radio Resource Control (RRC) signaling. In one embodiment, in step 503, the E-UTRAN, indicating the UE with a unable to serve error cause value using access stratum (AS) reject message and optionally includes the time value till which the UE should not consider the primary network and radio access technology for access network selection.

In an embodiment, the core network 400 can allocate a timer value to the UE, to indicate when to re-attempt to access primary network. The secondary PLMN (SPLMN) and timer are included by the core network 400 in the OVERLOAD START message (S1 signaling) for the E-UTRAN to include in the RRC messages. In one embodiment, after receiving the RRC reject message with the error indication as "unable to serve", the UE de-prioritizes the primary network and radio access technology (RAT) and initiates a new network reselection procedure immediately.

In an embodiment, the access network is E-UTRAN or UTRAN or GERAN and the like.

When a network is in an overload condition, the primary network (access network) can negotiate with a secondary network provider (core network for example Airtel) for access rights for the primary network users.

In an embodiment, the core network 400 of the operator 1 can negotiate with the core network 400 of operator 2, if it can offload users to the secondary network through enhanced core network signaling. The transparent containers can be exchanged between the core networks of the two operators when the core network of one of the operators is found to experience overload conditions, to access the possibility of offloading MTC/UE 100 users from one network to another network. If one of the networks gets a confirmation that it allows user offloading, the overloaded network can then indicate to the users of that network about the alternate PLMN to offload.

In an embodiment, the secondary PLMN can belong to another Radio access network technology. For example, offloading can be achieved from an LTE network to a GSM EDGE Radio Access Network (GERAN) and may having different PLMN identities and may belonging to different operators.

In an embodiment, the configured order of PLMN access is violated to achieve the secondary PLMN access for continued service access by MTC devices, if the SPLMN is included along with the unable to serve indication.

In general, most UEs are configured to attach and obtain services from the Home PLMN whenever the Home PLMN (primary network) is available.

In an embodiment, the primary PLMN indicates "unable to serve" to the UEs and to attach and obtain services from the secondary PLMN. In such a scenario, the periodic timers and temporary identities associated with the primary PLMN are turned off or deleted and a new explicit timer is started to retry the primary network. This new timer value can be set by the primary network in the SIB or in the NAS or in the AS message or the timer value is preconfigured in the UE.

Upon indication (unable to serve) by the primary network to a UE 100 to attach and obtain services from a secondary network, the UE 100 detaches from the primary network. Then UE 100 scans the frequencies associated with the secondary network (SPLMN) immediately and selects the best cell as per the cell selection criteria and attaches to the secondary network (SPLMN) by sending an attach message to the secondary network.

FIG. 6 illustrates a flow diagram for pre-configuration based approach for indicating the secondary PLMN to the UE, according to the embodiments as disclosed herein. The secondary PLMN is pre-configured in the UE 100 by the network or the service provider. If the primary PLMN of the UE explicitly indicates "unable to serve", then the UE automatically selects the configured next high priority PLMN by the primary network.

[0091] As depicted in the flow diagram 600, base station (eNodeB) broadcasts (601) the PLMNs to the UE 100, where the base station is shared by other access networks (for example PLMN A, PLMN B, PLMN C). If the home PLMN of a UE (say PLMN A) is overloaded, then the AS layer in the UE, indicates (602) that home PLMN is overloaded. Then the NAS layer of UE, checks (603) whether the required service is time controlled and if it is required service, then the NAS layer notifies (604) the AS layer to attach with the changed PLMN (either PLMN B or PLMN C) or secondary PLMN which is pre-configured in the UE (Universal Integrated Circuit Card (UICC)). Thus, the selection of PLMN is based on AS or NAS layer interaction within the UE 100. Further, the secondary PLMN (SPLMN) configuration in the USIM or in the device is either preconfigured by the network based on subscription through Over the Air (OTA) or Operation and Management (OAM) (OMA DM or (U) SIM OTA procedures) configuration by the network dynamically. The various actions in flow diagram 600 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 6 may be omitted.

In an embodiment, the network indicates the SPLMN through the NAS message during Attach or Location update procedure.

In an embodiment, when the Radio Access Network (RAN) or a base station is sharing one or more core network (for example Airtel, Vodafone and so on) the handover of inter core network (for example from Airtel to Vodafone) can be achieved by sending an alternate PLMN (A-PLMN) to the UE or MTC devices. Further, these devices (UEs) are routed to the other core networks through the radio access network (base station), which is being shared by the core networks.

In an embodiment, in network sharing scenario by core and access network, the base station (eNodeB) is pre-configured by a home PLMN (HPLMN) (say for example, PLMN A) to broadcast PLMN B (another core network, sharing the base station) in case of overloading in a primary network (PLMN A). The base station receives a S1-overload message from PLMN A or HPLMN for broadcasting PLMN B to the UEs.

Further, the base station checks whether the PLMN B is overloaded or not after receiving a S1-overload message from PLMN A or HPLMN of the UE 100. If the PLMN B is not overloaded, then it sends the PLMN B as the secondary PLMN in the EAB SIB for PLMN-A.

FIG. 7 illustrates a flow diagram explaining the process of providing service to the UE under unable to serve conditions, using NAS based approach, according to embodiments as disclosed herein. As depicted in the flow diagram 700, initially the UE 100 sends (701) a Non Access Stratum (NAS) message to obtain services from the serving network. If the serving network is overloaded or under unable to serve conditions, then the network sends (702) an unable to serve indication along with a secondary PLMN ID (optional) to the UE 100.

In an embodiment, network can be under "unable to serve" condition due to overload, maintenance, severe network failure, network entity malfunctioning and so on.

In an embodiment, when the network is awarded with a new spectrum, new inter operator rights enablement, then the UE 100 attached to the secondary network immediately, upon receiving the network selection behavior change indication from the primary network for obtaining the services.

In an embodiment, the network sends an indication for UE, which comprises a network selection behavior change, time period which indicates the UE 100 for not accessing the network during the time period. The time period is received as code point or an offset of an existing time period in memory of UE 100 or an explicit value.

The UE accesses the secondary network, after expiration of the time period, recalls initial PLMN order which is changed upon receiving the "unable to serve" indication from the primary network.

Further, the UE 100 checks (703) whether the NAS message received from the network includes a secondary PLMN ID. If the UE 100 determines that the NAS message includes a secondary PLMN ID, and then the UE 100 initiates (704) the network attach procedure using the indicated PLMN (secondary PLMN) immediately.

If the UE does not identify the secondary PLMN ID from the NAS message, then the UE 100, then the UE initiates (705) the network selection procedure and selects the next available priority PLMN based on the PLMN selector list configured in the UE 100.

Further, the UE 100 initiates (706) the network attach procedure with the selected PLMN.

The various actions in flow diagram 700 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 7 may be omitted.

FIG. 8 illustrates a computing environment implementing the method and system for providing service to user equipment under unable to serve conditions in a network. As depicted the computing environment 801 comprises at least one processing unit 804 that is equipped with a control unit 802 and an Arithmetic Logic Unit (ALU) 803, a memory 805, a storage unit 806, plurality of networking devices 808 and a plurality Input output (I/O) devices 807. The processing unit 804 is responsible for processing the instructions of the algorithm. The processing unit 804 receives commands from the control unit in order to perform its processing. Further, any logical and arithmetic operations involved in the execution of the instructions are computed with the help of the ALU 803.

The overall computing environment 801 can be composed of multiple homogeneous and/or heterogeneous cores, multiple CPUs of different kinds, special media and other accelerators. The processing unit 804 is responsible for processing the instructions of the algorithm. Further, the plurality of processing units 804 may be located on a single chip or over multiple chips.

The algorithm comprising of instructions and codes required for the implementation are stored in either the memory unit 805 or the storage 806 or both. At the time of execution, the instructions may be fetched from the corresponding memory 805 and/or storage 806, and executed by the processing unit 804.

In case of any hardware implementations various networking devices 808 or external I/O devices 807 may be connected to the computing environment to support the implementation through the networking unit and the I/O device unit.

The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements. The elements shown in Fig. 1, 3, 4, 5 and 8 include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

A method for providing continued services to a user equipment (UE) under unable to serve conditions in a communication network, wherein said method comprises:

receiving a network selection behavior change indication from a primary network for connecting to a secondary network immediately by said UE when said communication network is unable to serve said UE; and

attempting to attach to said secondary network by said UE immediately, upon receiving said network selection behavior change indication from said primary network for obtaining said services.
The method as in claim 1, wherein said indication from said primary network comprises at least one of: a network selection behavior change indication, an unable to serve indication, sever network failure indication secondary Public Land Mobile Network (PLMN) ID, time period for said UE to obtain said services from said secondary network and not to retry the primary network, further said time period is received as at least one of: code point, an offset of an existing time period in at least one of: memory of said UE, an explicit value.
The method as in claim 2, wherein said UE receives said indication from said primary network in at least one of: System Information Block (SIB), Access Stratum (AS) message, Non Access Stratum (NAS) message, wherein said indication is provided to at least one UE individually.
The method as in claim 3, wherein said unable to serve indication is communicated to said UE over a NAS reject message, further said indication is communicated in a cause value in said NAS reject message.
The method as in claim 2, wherein said unable to serve indication is treated as at least one of: said network selection behavior change indication, de-prioritization of serving PLMN indication is communicated over a RRC reject message.
The method as in claim 3, wherein said primary network provides a time period to said UE informing not to re-attempt for accessing said primary network, further said time period is communicated to said UE over a AS reject message.
The method as claim 2, wherein said access network provides said at least one of: secondary PLMN ID, time period to re-attempt for accessing said access network.
The method as in claim 3, wherein said primary network pre-configures said UE to connect to said secondary network, when said primary network is in said unable to serve conditions, wherein said primary network pre-configures said secondary PLMN ID.
The method as in claim 6, wherein said primary network configures said UE to connect said secondary network dynamically using said NAS message.
The method as in claim 3, wherein said at least one of: core network, access network routes said UE when said communication network is shared between said core network and said access network, further said at least one of: core network, access network sends an alternate PLMN to said UE when said at least one of: core network, access network is in said unable to service conditions.
The method as in claim 8, wherein said UE executes said network access behavior change after receiving a new PLMN ID from said primary network which is not already present in said UE, wherein said new PLMN ID is not in a list comprises at least one of: registered PLMNs, equivalent PLMNs, roaming PLMNs.
The method as in claim 11, wherein said UE changes said network access behavior by prioritizing said received PLMN with respect to all other existing PLMN IDs already present in said UE based on the order of priority and access as indicated by said primary network.
The method as in claim 9, wherein said primary network indicates a cell ID in said at least one of: SIB, AS, NAS message, further said UE receives said cell ID after expiry of a timer value associated with said secondary PLMN access.
The method as in claim 7, wherein said access network broadcasts said secondary PLMN ID, when said core network indicates an S1-overload indication to said access network, further said secondary PLMN is selected based on the PLMN selector list configured in said UE.
The method as in claim 1, wherein said method further comprises:

receiving said network selection behavior change indication from said primary network for connecting to said secondary network immediately by said UE when said communication network is provided with at least one of: new spectrum, new inter operator rights enablement; and

attempting to attach to said secondary network by said UE immediately, upon receiving said network selection behavior change indication from said primary network for obtaining said services.
The method as in claim 2, wherein said UE after expiry of said time period to access said secondary network recalls initial PLMN order which is changed upon receiving said "unable to serve" indication from said primary network.
A system for providing continued services to a user equipment (UE) under unable to serve conditions in a communication network, wherein said system comprises at least one core network, access network, said UE, further said system is configured for performing the same steps as claimed in at least one of claims 1 to 20.
A communication network for providing services to a user equipment (UE) under unable to serve conditions, wherein said communication network is configured to:

provide an indication to said UE for executing a network selection behavior change, wherein said UE forgoes any invocation of back off timers and continued primary network access attempts; and

initiate an immediate connection attempt to a secondary network.
The communication network as in claim 18, wherein said communication network comprises said at least one of: core network, access network.
The communication network as in claim 19, wherein said primary network is at least one of: current serving network of said UE, selected network as best available network by said UE, currently attached network of said UE, home Public Land Mobile Network (HPLMN) of said UE.
The communication network as in claim 19, wherein said secondary network is at least one of: available highest priority PLMN in PLMN selector list in said UE, PLMN ID communicated to said UE by said primary network, said primary network with different RAT.
The communication network as in claim 21, wherein said PLMN selector list is at least one of: "HPLMN selector with Access Technology", "Operator controlled PLMN selector with Access Technology", "User Controlled PLMN Selector with Access Technology", "Forbidden PLMNs", "Equivalent HPLMN", separate list of said PLMN in priority order used by said UE when said primary network indicates "unable to serve" indication.
The communication network as in claim 18, wherein said communication network is configured to provide said indication to said UE in at least one of: System Information Block (SIB), Access Stratum (AS) message, Non Access Stratum (NAS) message.
The communication network as in claim 19, wherein said primary network is configured to provide a time period that indicates time duration for said UE not to re-attempt for accessing said primary network.
The communication network as in claim 18, wherein said primary network pre-configures a timer value in said UE, wherein said pre-configured timer value is stored in said UE.
The communication network as in claim 18, wherein said communication network is configured to route said UE through at least one of: core network, access network, when said communication network is shared between said core network and said access network, further said at least one of: core network, access network is configured to send an alternate PLMN to said UE, when said at least one of: core network, access network is in said unable to service conditions.
The communication network as in claim 24, wherein said access network is configured to broadcast a secondary PLMN ID, when said core network indicates an S1-overload indication to said access network.
A user equipment (UE) for obtaining continued services from at least one primary network, secondary network under unable to serve conditions, wherein said UE comprises:

an integrated circuit further comprising at least one processor;

at least one memory having a computer program code within said circuit;

said at least one memory and said computer program code with said at least one processor cause said UE to:

receive a network selection behavior change indication from said primary network for connecting to said secondary network immediately; and

attempt to attach to said secondary network, upon receiving said network selection behavior change indication from said primary network for obtaining said services.
The method as in claim 1 or the UE as in claim 28, wherein said primary network, said secondary network is at least one of: core network, access network.
The method as in claim 1 or the UE as in claim 28, wherein said primary network, said secondary network is at least one of: core network, access network,

wherein said primary network is at least one of: current serving network of said UE, selected network as best available network by said UE, currently attached network of said UE, home Public Land Mobile Network (HPLMN) of said UE.
The method as in claim 1 or the UE as in claim 28, wherein said primary network, said secondary network is at least one of: core network, access network,

wherein said secondary network is at least one of: available highest priority PLMN in PLMN selector list in said UE, PLMN ID communicated to said UE by said primary network, said primary network with different RAT.
The method as in claim 1 or the UE as in claim 28, wherein said primary network, said secondary network is at least one of: core network, access network,

wherein said secondary network is at least one of: available highest priority PLMN in PLMN selector list in said UE, PLMN ID communicated to said UE by said primary network, said primary network with different RAT, and

wherein said PLMN selector list is at least one of: "HPLMN selector with Access Technology", "Operator controlled PLMN selector with Access Technology", "User Controlled PLMN Selector with Access Technology", "Forbidden PLMNs", "Equivalent HPLMN", separate list of said PLMN in priority order used by said UE when said primary network indicates "unable to serve" indication.
The UE as in claim 28, wherein said UE is configured to receive an indication from said primary network comprises at least one of: an overload indication, unable to serve indication, severe network failure indication, secondary Public Land Mobile Network (PLMN) ID, time period to obtain said services from said secondary network, further said UE is configured to access said primary network after expiration of said time period and said UE is configured to recall initial PLMN order which is changed upon receiving said "unable to serve" indication from said primary network.
The UE as in claim 30, wherein said UE is configured to receive said indication from said primary network in at least one of: System Information Block (SIB), Access Stratum (AS) message, Non Access Stratum (NAS) message.
The UE as in claim 28, wherein said UE is configured to receive a time period which indicates not to re-attempt for accessing said primary network.
The UE as in claim 28, wherein said UE is configured to receive at least one of: secondary PLMN ID, time period for not to re-attempt for accessing said access network.
The UE as in claim 28, wherein said UE is configured to connect to said secondary network, when said primary network is in said unable to serve conditions, wherein said primary network is configured to provide said secondary PLMN ID to said UE.