DESC:RELATED APPLICATION

Benefit is claimed to Indian Provisional Application No. 3199/CHE/2014 titled "METHOD TO IMPROVE THE CIRCUIT SWITCHED SERVICES AVAILABILITY TO THE USER" filed on 30th June 2014, which is herein incorporated in its entirety by reference for all purposes.

FIELD OF INVENTION

The present invention in general relates to wireless networks, and more particularly relates to a method of improving circuit switched services availability to user equipment during abnormal scenarios.

BACKGROUND OF THE INVENTION

The third generation partnership project (3GPP) has developed universal mobile telecommunications system (UMTS) to meet the growing demands of mobile and Internet applications. A conventional UMTS network architecture and signaling connections in the UMTS network is illustrated in Figure 1. As shown in Figure 1, the UMTS network architecture comprises of user equipment (UE), and a Public Land Mobile Network (PLMN) which is further divided into two parts namely a core network (CN) and a radio access network (RAN). The CN is again subdivided into a Circuit Switched (CS) service domain and a Packet Switched (PS) service domain wherein the UE is configured to provide both CS and PS services. The CS service domain supports circuit switched services like voice, text etc. and the PS service domain supports packet or Internet-based services like streaming movies, VOIP calls, video calls and the like in the form of data packets. The RAN may be a UMTS terrestrial RAN (UTRAN). The UE communicates with the UTRAN network using a radio resource connection (RRC). At a time, only one RRC connection can be established between the UE and the core network. In UMTS, the CS service domain comprises of a Mobile Switching Center (MSC) for managing voice based services and a visited location register (VLR) database for storing UE’s location within a serving network. The PS service domain comprises of a Serving GPRS Support Node (SGSN) for handling several mobility and routing dependent functions needed for PS-based services. The CN also comprises a home location register (HLR) where all PS location, CS location and subscriber related information is stored. The UE and the UTRAN network communicates via an interface UU whereas the UTRAN and CN communicate via lU interface.

The UE performs location area update (LAU), a regular procedure of informing current location of the UE to the core network. The UE also performs location update due to any of the conditions specified in technical specification (TS) 24.008, section 4.4.1. However, the LAU procedure may get failed due to one or more conditions such as location update reject with cause #17 network failure for maximum attempts, poor signaling connection with the network, random access failure, RR connection failure, T3210 timeout etc., as mentioned in TS 24.008 section 4.4.4.9. One such scenario is illustrated in Figure 2.

Let us assume that radio access bearers (RABs) are established between UE, UTRAN and the core network (CS and PS domain) and a radio bearer is established between UE and the UTRAN. Also, consider that the UE establishes packet switching (PS) signaling connection with the network (PMM_connected). As shown in Figure 2, the UE encountered a trigger due to TS 24.008 section 4.4.1 and sends CS registration request using location update request (LAU_REQ) to the core network. However, the UE cannot avail the services from the CN and location update procedure got failed. The UE waits for a time interval specified by the timer T3211 to resend the LAU request. However, the UE is allowed to resend the LAU request upon the expiry of timer T3211 for a maximum of ‘n’ times. The value ‘n’ depends on the latest versions of the 3GPP 24.008 specifications.

On the expiry of nth attempt, the Radio resource (RR) connection or CS signaling connection gets released between the UE and the CN. When the CS signaling connection got released, the UE fails to make any voice call. Under this scenario, as per the current specification the UE is allowed to perform PLMN selection to avail CS services from the selected PLMN network other than the serving network. However, it is not possible for the UE to perform PLMN selection as only CS connection got released and PS signaling connection is still ongoing. Therefore, the UE cannot avail CS services as long as the PS signaling connection is not released by the PS core network.

Hence, there is a need to improve the availability of circuit switched services for quicker access to various network services to the user equipment during abnormal conditions.

SUMMARY OF THE INVENTION

The various embodiments herein disclose a method of improving circuit switched (CS) service availability to user equipment. The method comprises of sending, by a user equipment (UE), at least one location area update (LAU) message to initiate a location update procedure to a CS core network (CN), determining a CS signaling connection which is released due to a failure in the location update procedure, identifying an ongoing packet switched (PS) signaling connection when the CS signaling connection is released, releasing the identified ongoing PS signaling connection, and performing a public landline mobile network (PLMN) selection for obtaining CS services from the core network in response to releasing the identified ongoing PS signaling connection.

According to an embodiment of the present invention, the failure is due to an occurrence of abnormal scenario at the UE side.

According to an embodiment of the present invention, the abnormal scenario at the UE side comprises at least one of: access barred because of access class control, answer to random access is an immediate assignment reject message, random access failure, RR connection failure, expiry of T3210 timer, RR connection release before end of normal procedure, location update reject by the network, and location update failed procedurally.

According to an embodiment of the present invention, the method further comprises of detecting that an update status is different from updated status, detecting that a location area identity (LAI) is different from an LAI received on a broadcast control channel (BCCH) from a current serving cell of the UE, or detecting that an attempt count value is greater or equal to 4.

According to an embodiment of the present invention, wherein in releasing the identified ongoing PS signaling connection, the method comprises of sending a request to a PS core network through a UMTS terrestrial radio access network (UTRAN) for releasing the identified ongoing PS signaling connection; and releasing the ongoing PS signaling connection by the PS core network in response to the request received from the UTRAN; and indicating, by the UTRAN, the release of PS signaling connection to the UE.

Embodiments herein further disclose user equipment (UE) for improving circuit switched availability which comprises a memory, a controller module adapted for sending at least one location area update (LAU) message to initiate a location update procedure to a CS core network (CN), determining a CS signaling connection which is released due to a failure in the location update procedure, identifying an ongoing packet switched (PS) signaling connection when the CS signaling connection is released, releasing the identified ongoing PS signaling connection, and performing a public landline mobile network (PLMN) selection for obtaining CS services from the core network in response to releasing the identified ongoing PS signaling connection.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 illustrates a conventional UMTS network architecture describing signaling connections in the UMTS network.

Figure 2 illustrates an exemplary problem scenario where user equipment fails to perform location update procedure with a core network.

Figure 3 illustrates a flow diagram explaining a location area update procedure performed by a user equipment, according to one embodiment of the present invention.

Figure 4 is a process flowchart illustrating an exemplary method of improving circuit switched services to a user equipment during abnormal cases, according to one embodiment.

Figure 5 is a block diagram illustrating one or more components of a user equipment for availing circuit switching services from the network, according to one embodiment.

Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of improving circuit switched services availability to user equipment. The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments. The present invention can be modified in various forms. Thus, the embodiments of the present invention are only provided to explain more clearly the present invention to the ordinarily skilled in the art of the present invention. In the accompanying drawings, like reference numerals are used to indicate like components.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include operatively connected or coupled. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Figure 3 illustrates a flow diagram explaining a location area update procedure performed by a user equipment, according to one embodiment of the present invention. The flow diagram provides a solution to the problem scenario explained in Figure 2. When the UE fails to initiate location update procedure due to any of the abnormal scenarios mentioned in section 4.4.4.9 of TS 24.008, the UE tends to perform PLMN search to avail CS services. However, before performing the PLMN search, the UE checks whether any PS connection is ongoing. If any PS connection is ongoing, then the UE sends signaling connection release indication request to radio access network. In response to the request the RAN releases PS connection which is ongoing and sends RRC connection release indication to the UE. Upon receiving the indication of RRC connection release the UE performs PLMN search to avail CS services from the network.

Figure 4 is a process flowchart illustrating an exemplary method of improving circuit switched services to a user equipment during abnormal cases, according to one embodiment. At step 402, at least one location area update message is sent by user equipment (UE) to a core network to initiate location update procedure. The location area update message is generally sent by the UE to indicate a current location of the UE to the network so as to obtain one or more services from the network. The one or more services may include a circuit switched (CS) service (e.g. a voice call service), a packet switched (PS) service (e.g. a video call, a VOIP call ) etc. In order to avail these services the UE updates its location periodically as defined in section 4.4.1 of technical specification. Upon successful location area update, the UE avails both CS and PS services from the network. The location area information associated with the UE is maintained in visited location register (VLR) of the core network.

However, in some cases the location area update procedure fails due to abnormal scenarios happened at the UE. The abnormal scenarios as described in TS 24.008 section 4.4.4.9 are access barred because of access class control, answer to random access is an immediate assignment reject message, random access failure, RR connection failure, expiry of T3210 timer; RR connection release before end of normal procedure; Location update reject by the network; and Location update failed procedurally. When any of these scenarios occurred, the UE cannot update the location area to the network and hence the CS signaling connection got released. At step 404, it is determined that the CS signaling connection got released due to a failure in the location update procedure. At step 406, an ongoing PS signaling connection is identified by the UE when the CS signaling connection got released. At step 408, the identified ongoing PS signaling connection is released by the UE and at step 410, a PLMN selection is performed for obtaining CS services from the network in response to releasing of identified PS signaling connection.

Therefore, for all the cases where MM is in PLMN_SEARCH sub state and GMM is in PMM_CONNECTED functional state, the UE can initiate PS signaling connection release and perform PLMN selection. In other words, whenever the UE desires to do PLMN selection while a PS signaling connection is ongoing, the UE always releases the PS signaling connection and then performs PLMN selection in order to avail CS services from the network.

Figure 5 is a block diagram illustrating one or more components of a user equipment for availing circuit switched (CS) services from the network during abnormal scenarios, according to one embodiment. The user equipment 500 may be a mobile phone, smart phone, personal digital assistant, tablet, phablet, laptop and the like. The user equipment 500 is configured to provide circuit switched and packet switched services.

As shown in Figure 5, the user equipment 500 includes one or more processors 502, a storage device 503, a memory 504, and a network interface 502. In addition, the user equipment 500 includes a user interface 506 and a controller module 505.

The electronic device may include additional components not shown in Figure 5 for purposes of clarity. For example, the user equipment 500 may also include a microphone and speaker. The user equipment 500 may also include a battery that provides power to the components of the electronic device 500. The user equipment 500 may also include other user interface components, such as a keypad, trackball, mouse, or other such user interfaces that allow the user to interact with the electronic device 500. Moreover, the components of the user equipment 500 shown in Figure 3 may not be necessary in every example of the electronic device 500.

The processor 501 may be configured to implement functionality and/or process instructions for execution within the user equipment 500. The processor 501 may be capable of processing instructions stored in the memory 504 or instructions stored on the controller module 505. The processor 501 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or integrated logic circuitry. Additionally, the functions attributed to the processor 501, in this disclosure, may be embodied as software, firmware, hardware or any combination thereof.

The storage device 503 may include one or more computer-readable storage media. The storage device may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the storage device 504 may, in some examples, be considered a non-transitory computer-readable storage medium. The term “non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term “non-transitory” should not be interpreted to mean that the storage device is non-movable. In some examples, the storage device 503 may be configured to store larger amounts of information than the memory 504. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

The memory 504 may be configured to store information within the user equipment 500 during operation. The memory 504 may, in some examples, be described as a computer-readable storage medium. The memory may be described as a volatile memory, meaning that the memory 504 does not maintain stored contents when the computer is turned off. Examples of volatile memories include random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories known in the art.

The controller module 505 is configured for maintaining state information regarding CS and PS connections of UE, status of UE whether it is in idle or in mobility state etc. The controller module 505 is configured for sending at least one location area update (LAU) message to initiate a location update procedure. The controller module 505 is also configured for determining a release of CS signaling connection due to a failure in the location update procedure. The controller module 505 is also configured for identifying an ongoing packet switched (PS) signaling connection when the CS signaling connection is released. Further, the controller module 505 is configured for releasing the identified ongoing PS signaling connection and performing public landline mobile network (PLMN) selection for obtaining CS services from the network.

The user equipment 500 may utilize network interface 502 to communicate with external devices via one or more networks, such as one or more wireless networks. The network interface 502 may be a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and receive information. Examples of such network interfaces 502 may include Bluetooth®, 3G and WiFi® radios in mobile electronic devices as well as USB. Examples of such wireless networks may include WiFi®, Bluetooth®, and 3G. In some examples, the user equipment 500 may utilize the network interface 502 to wirelessly communicate with an external device (not shown) such as a server, mobile phone, or other networked electronic device.

The user interface (“UI”) 506 allows a user of the electronic device to interact with electronic device 500. The UI 506 may generate a graphical user interface (“GUI”) that allows a user to initiate commands. In some embodiments, the UI 506 generates a GUI that is displayed on touch sensitive screen (“touch screen”). The GUI may include one or more touch sensitive UI elements. For example, a user may be able to interact with the user equipment 500 and initiate a command by touching one or more of the touch sensitive UI elements displayed on touch sensitive screen and/or hovering over UI elements displayed on touch sensitive screen. The touch sensitive screen may comprise of a variety of display devices such as a liquid crystal display (LCD), an e-ink display, a cathode ray tube (CRT), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

The embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Furthermore, the various devices, modules, and the like described herein may be enabled and operated using hardware circuitry, for example, complementary metal oxide semiconductor based logic circuitry, firmware, software and/or any combination of hardware, firmware, and/or software embodied in a machine readable medium. For example, the various electrical structure and methods may be embodied using transistors, logic gates, and electrical circuits, such as application specific integrated circuit.

,CLAIMS:
1. A method of improving circuit switched (CS) service availability to a user equipment (UE), the method comprising steps of:
sending, by a user equipment (UE), at least one location area update (LAU) message to initiate a location update procedure to a CS core network (CN);
determining a CS signaling connection which is released due to a failure in the location update procedure;
identifying an ongoing packet switched (PS) signaling connection when the CS signaling connection is released;
releasing the identified ongoing PS signaling connection; and
performing a public landline mobile network (PLMN) selection for obtaining CS services from the core network in response to releasing the identified ongoing PS signaling connection.

2. The method as claimed in claim 1, wherein the failure is due to an occurrence of abnormal scenario at the UE side.

3. The method as claimed in claim 2, wherein the abnormal scenario at the UE side comprises at least one of:
barring an access due to an access class control;
receiving an immediate assignment reject message from the CS core network;
a random access failure;
an Radio resource (RR ) connection failure;
an expiry of T3210 timer;
an RR connection release before end of a successful location update procedure;
receiving a location update rejection from the CS core network; and
location area update failed procedurally.

4. The method as claimed in claim 3, further comprising:
detecting that an update status is different from updated status;
detecting that a location area identity (LAI) is different from an LAI received on a broadcast control channel (BCCH) from a current serving cell of the UE; or
detecting that an attempt count value is greater or equal to 4.

5. The method as claimed in claim 1, wherein releasing the identified ongoing PS signaling connection comprises of:
sending, by the UE, a request to a PS core network for releasing the identified ongoing PS signaling connection; and
releasing the ongoing PS signaling connection by the PS core network in response to the request received; and
receiving, by the UE, an indication in response to the release of PS signaling connection.

6. A user equipment comprising:
a controller module; and
a memory comprising computer-executable instructions that configure the controller module to perform steps comprising:
sending at least one location area update (LAU) message to initiate a location update procedure to a CS core network (CN);
determining a CS signaling connection which is released due to a failure in the location update procedure;
identifying an ongoing packet switched (PS) signaling connection when the CS signaling connection is released;
releasing the identified ongoing PS signaling connection; and
performing a public landline mobile network (PLMN) selection for obtaining CS services from the core network in response to releasing the identified ongoing PS signaling connection.

7. The user equipment as claimed in claim 5, wherein releasing the identified ongoing PS signaling connection when the CS signaling connection is released comprises:
sending a request to a PS core network through a UMTS terrestrial radio access network (UTRAN) for releasing the identified ongoing PS signaling connection; and
releasing the ongoing PS signaling connection by the PS core network in response to the request received; and
receiving an indication, in response to the release of PS signaling connection .