CLIAMS:
1. A method for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported user equipments, the method comprising steps of:
sending a combined registration request message, by the user equipment, for at least one evolved packet system (EPS) service through a first radio access network to a communication network;
receiving an EPS service registration accept message comprising an indicator that indicates that a circuit switched fall back (CSFB) is not supported;
disabling the a first radio access network on receiving the EPS service registration accept message and in response to the indicator that indicates that CSFB is not supported; and
switching to a second radio access network when the user equipment has a voice centric setting and IMS voice is not available.

2. The method of claim 1, further comprising:
sending a request by the user equipment to the network, for registering for the PS and CS explicitly seeking SGs link related information from network;
receiving a request accept message along with an indicator indicating a SGs link information from the network; and
switching to the first radio access network if the SGs link is present in the request accept message; and
remaining in the second radio access network if the SGs link is not present.

3. The method as claimed in claim 2, wherein switching to the first radio access network if the SGs link is present in the request accept message comprises of:
broadcasting information related to the SGs link, a timer value for re-enabling first radio access network based on network topology and UE’s movement, packet temporary mobile subscriber identity (P-TMSI) and IP Multimedia Subsystem (IMS) voice over packet switched (VoPS) indication to the user equipment by the network.

4. The method as claimed in claim 2, further comprising:
storing, by the user equipment, mobility management entity (MME) IDs received in the combined attach message sent from the network in a memory of the user equipment.

5. The method of claim 1, wherein the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

6. The method of claim 1, wherein the second radio access network is one of an UTRAN, global system for mobile communications (GSM) enhanced data rates for GSM evolution (EDGE) radio access network (GERAN).

7. The method of claim 1, wherein the combined registration request message is at least one of an ATTACH request message or a TRACKING AREA UPDATE request message, along with an indicator to indicate that it is a combined registration request.

8. The method of claim 1, wherein the indicator is a network feature support information element including a SGs bit along with neighbor TA list information with necessary configuration.

9. The method as claimed in claim 8, further comprising:
storing, by the user equipment, a neighbor TAI list with supported feature based on the TAU/Attach accept message received from the network in a memory of the user equipment.

10. A method for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported user equipments, the method comprising steps of:
sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network;
receiving an EPS service registration accept message comprising an indicator that indicates that circuit switched fall back (CSFB) is not supported; and
remaining in the current radio access network when the user equipment has a data centric usage setting.

11. A method of handling LTE and voice services for a user equipment with voice centric usage settings, the method comprising steps of:
sending a combined registration request message for at least one evolved packet system (EPS) service via a first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause “CS domain not available”;
disabling the first radio access network and sending a registration request to a second radio access network if the combined registration request is accepted only for the EPS with reject cause “CS domain not available”;
checking if the registration request for the second radio access network is successful;
remaining in the second radio access network if the registration accept/reject message comprises an indicator that indicates that SGs link is not available;
enabling the first radio access network on receiving a combined registration accept/reject message comprising an indicator that indicates SGs link is available; and
acquiring the CSFB services by sending the combined registration request.

12. The method of claim 11, further comprising:
enabling the first radio access network if the second radio access network is not found;
remaining on the same PLMN if no other PLMN is found;
sending an update registering request for the EPS service including SGs link information required bit; and
acquiring the CSFB services by sending the combined registration request upon receiving an EPS service registration accept message comprising the indicator that indicates that the circuit switched fall back (CSFB) is supported for the same PLMN.

13. The method of claim 11, further comprising:
verifying if the combined registration request message is rejected with “CS domain not available”;
disabling the first radio access network if the combined registration request is rejected; and
switching to the second radio access network if IMS Voice is not available.

14. The method of claim 11, wherein the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

15. The method of claim 11, wherein the second radio access network is one of a UTRAN, global system for mobile communications (GSM) enhanced data rates for GSM evolution (EDGE) radio access network (GERAN).

16. The method of claim 11, wherein the combined registration request message is at least one of an ATTACH request message or a ROUTING AREA UPDATE request message along with an indicator to indicate that it is a combined registration request and with a SGs link information required bit.

17. The method of claim 11, wherein the user equipment with voice centric usage settings is a single RF device with CS/PS Mode1.

18. A method of handling LTE and voice services for a user equipment with data centric usage settings, the method comprising steps of:
sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network;
verifying if the combined registration request is accepted for the EPS with cause “CS domain not available”;
remaining on a PLMN associated with the first radio access network if the combined registration request is accepted only for the EPS with the “CS domain not available”;
sending an update registering request for the EPS service including SGs link information required bit; and
acquiring the CSFB services by sending the combined registration request upon receiving an EPS service registration accept message comprising an indicator that indicates that the SGs link is available.

19. The method of claim 18, wherein the first radio access is Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

20. The method of claim 18, wherein indicator is an SGs link bit value present in the network feature support IE. .

21. The method of claim 18, wherein the user equipment with data centric usage settings is a single RF device with CS/PS Mode2.

22. A method of handling data service and voice service for a user equipment with voice centric usage settings, the method comprising steps of:
enabling a first radio access network having a first radio frequency for a dual RF device;
sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause 18; and
switching the UE to PS Mode 1 on RF1 with the first radio access network and enabling CHIP2 with RF2 to latch to the second radio access network; and
performing an action based on an accept message for the registration request.

23. The method of claim 22, wherein performing the action based on the response of the combined registration request comprises of:
verifying if the accept message for the combined registration request indicates the presence of an SGs link with the first access network on the first radio access frequency;
switching to a dual RF configuration for the UE if the SGs link is not present; and
changing the device to PS mode; and
acquiring data services from the first access network using the first radio access frequency.

24. The method of claim 22, wherein performing the action based on the response of the combined registration request comprises of:
verifying if the accept message for the combined registration request indicates the presence of an SGs link with the second access network on the RF2;
switching to a dual RF configuration for the UE if the SGs link is not present;
changing the device to PS mode; and
acquiring voice services from the second access network using the second radio access frequency.

25. The method as claimed in claim 22, further comprising:
receiving a detach request message with type “re-attach required” sent by the network when the SGs link is present; and
switching to the first access network upon receiving the SGs link present indication in the subsequent registration accept message on the second radio access network.

26. The method of claim 22, wherein the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

27. The method of claim 22, wherein the second radio access network is one of an UTRAN, global system for mobile communications (GSM) enhanced data rates for GSM evolution (EDGE) radio access network (GERAN).

28. A method of handling of data services and voice services for a dual RF user equipment with data centric usage settings, the method comprising steps of:
enabling a first radio access network on the user equipment on RF1 and CHIP1;
sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause 18;
remaining on the same PLMN if no other PLMN belonging to the first radio access network is present; and
enabling RF2 on CHIP2 with second radio access network for providing the voice service if required; and
disabling the RF2 on CHIP2 when acquiring the CSFB services using RF1 on CHIP1 by sending the combined registration request when the registration accept message indicates the presence of the SGs link for the PLMN for which reject cause 18 was received.

29. The method as claimed in claim 28, wherein the accept message further comprises a timer value, packet temporary mobile subscriber identity (P-TMSI) and IP Multimedia Subsystem (IMS) voice over packet switched (VoPS) bit.

30. A system for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported device, the system comprising a user equipment having at least one element adapted for:
sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network to a communication network;
receiving an EPS service registration accept message comprising an indicator that indicates that a circuit switched fall back (CSFB) is not supported;
disabling the a first radio access network on receiving the EPS service registration accept message and in response to the indicator that indicates that CSFB is not supported; and
switching to a second radio access network when the user equipment has a voice centric setting and IMS voice is not available.

31. The system as claimed in claim 30, wherein the user equipment further comprises at least one element adapted for:
sending a request to the network, for registering for the PS and CS for obtaining SGs link related information from network;
receiving a request accept message along with an indicator indicating a SGs link information from the network; and
switching to the first radio access network if the SGs link is present in the request accept message; and
remaining in the second radio access network if the SGs link is not present.

32. The system as claimed in claim 30, wherein the user equipment is further adapted for:
broadcasting information related to the SGs link, a timer value for re-enabling first radio access network based on network topology and UE’s movement, packet temporary mobile subscriber identity (P-TMSI) and IP Multimedia Subsystem (IMS) voice over packet switched (VoPS) indication to the user equipment by the network.

33. The system as claimed in claim 30, wherein the user equipment further comprises at least one element adapted for:
storing the mobility management entity (MME) IDs received in the combined attach message sent from the network.

34. The system as claimed in claim 30, wherein the user equipment further comprises at least one element adapted for:
storing a neighbor TAI list with supported features based on the TAU/Attach accept message received from the network.

35. A system for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported devices, the system comprising a user equipment having at least one element adapted for:
sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network;
receiving an EPS service registration accept message comprising an indicator that indicates that circuit switched fall back (CSFB) is not supported; and
remaining in the current radio access network; when the user equipment has a data centric usage setting.

36. A system for of handling LTE and voice services for a user equipment with voice centric usage settings, the system comprising at least one element adapted for:
sending a combined registration request message for at least one evolved packet system (EPS) service via a first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause “CS domain not available”.
disabling the first radio access network and sending a registration request to a second radio access network if the combined registration request is accepted only for the EPS with reject cause “CS domain not available”;
checking if the registration request for the second radio access network is successful;
remaining in the second radio access network if the registration accept/reject message comprising an indicator that indicates that SGs link is not available;
enabling the first radio access network on receiving a combined registration accept/reject message comprising an indicator that indicates SGs link is available; and
acquiring the CSFB services by sending the combined registration request.

37. The system as claimed in claim 36, further comprising at least one element adapted for:
enabling the first radio access network if the second radio access network is not found;
remaining on a same PLMN if no other PLMN is found;
sending a update registering request for the EPS service including SGs link information required bit; and
acquiring the CSFB services by sending the combined registration request upon receiving an EPS service registration accept message comprising an indicator that indicates that the circuit switched fall back (CSFB) is supported for the same PLMN.

38. The system as claimed in claim 36, further comprising at least one element adapted for:
verifying if the combined registration request message is rejected with “CS domain not available”;
disabling the first radio access network if the combined registration request is rejected; and
switching to the second radio access network if IMS Voice is not available.

39. The system as claimed in claim 36, wherein the at least one element comprises a user equipment with voice centric usage settings is a single RF device with CS/PS Mode1.

40. A system for handling LTE and voice services for a user equipment with data centric usage settings, the system comprising at least one element adapted for:
sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network;
verifying if the combined registration request is accepted for the EPS with cause “CS domain not available”;
remaining on a PLMN associated with the first radio access network if the combined registration request is accepted only for the EPS with the “CS domain not available”;
sending a update registering request for the EPS service including SGs link information required bit; and
acquiring the CSFB services by sending the combined registration request upon receiving an EPS service registration accept message comprising an indicator that indicates that the SGs link is available.

41. A system for handling data service and voice service for a user equipment with voice centric usage settings, the system comprising at least one element adapted for:
enabling a first radio access network having a first radio frequency for a dual RF device;
sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause 18; and
switching the UE to PS Mode 1 on RF1 with the first radio access network and enabling CHIP2 with RF2 to latch to the second radio access network; and
performing an action based on an accept message for the registration request.

42. The system as claimed in claim 41, wherein the element adapted for performing the action based on the accept message for the registration request is further adapted for:
verifying if the accept message for the combined registration request indicates the presence of an SGs link with the first access network on the first radio access frequency;
switching to a dual RF configuration for the UE if the SGs link is not present; and
changing the device to PS mode;
acquiring data services from the first access network using the first radio access frequency.

43. The system as claimed in claim 41, wherein the element adapted for performing the action based on the accept message for the registration request is further adapted for:
verifying if the accept message for the combined registration request indicates the presence of an SGs link with the second access network on the RF2;
switching to a dual RF configuration for the UE if the SGs link is not present;
changing the device to PS mode; and
acquiring voice services from the second access network using the second radio access frequency.

44. The system as claimed in claim 41, further comprising at least one element adapted for:
receiving a detach request message with type “re-attach required” sent by the network when the SGs link is present; and
switching to the first access network upon receiving the SGs link present indication in the subsequent registration accept message on the second radio access network.

45. A system for handling of data services and voice services for a dual RF user equipment with data centric usage settings, the system comprising at least one element adapted for:
enabling a first radio access network on the user equipment on RF1 and CHIP1;
sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network;
verifying if the combined registration request is accepted for the EPS with reject cause 18;
remaining on the same PLMN if no other PLMN belonging to the first radio access network is present; and
enabling RF2 on CHIP2 with second radio access network for providing the voice service if required; and
disabling the RF2 on CHIP2 when acquiring the CSFB services using RF1 on CHIP1 by sending the combined registration request when the registration accept message indicates the presence of the SGs link for the PLMN for which reject cause 18 was received. ,TagSPECI:FIELD OF THE INVENTION

The present invention generally relates to handling of communication services in wireless communication and particularly relates to a system and method for efficient handling of LTE and Voice services for single and dual RF supported mobile communication devices.

BACKGROUND OF THE INVENTION

In a typical mobile communications environment, user equipment (UE) may communicate voice and/or data signals with one or more service networks via cellular stations of the service networks 3GPP has provision to accommodate multiple radio access systems like 2G, 3G, Long term evolution (LTE in an integrated manner, and can provide mobility management seamlessly among such systems.

When a subscriber on the LTE network makes or receives a voice call, the network redirects the device to the 2G/3G network (if IMS voice is not available as defined in 3GPP 24.301 sections 4.3.1) where the voice call is attempted. Upon completion of the voice call the device must return to the LTE network. Mobile user equipment’s (UEs) can be provisioned to be data centric or voice centric. In addition, UE includes usage settings (see section 4 of 3GPP TS 24.301). These settings control how a UE accesses voice services through circuit switched fallback (CSFB).

When a UE sends a combined registration request for evolved packet system (EPS) and non-EPS services (e.g., an ATTACH request or a TRACKING AREA UPDATE request) to a long term evolution (LTE) network, the network may indicate that the combined registration is failed for CS domain (example EMM cause #18 “CS domain not available”) . Typically, a voice centric UE disables the LTE (E-UTRAN) and moves to a second generation (2G) or third generation (3G) radio access technology (RAT) if IMS voice is not available and voice domain preference for E-UTRAN is not “IMS PS voice only”. Further the UE will not attempt to re-enable E-UTRA and perform the combined update procedure in LTE (ATTACH/TAU) with current PLMN until switching off the UE or until the UICC containing the USIM is removed or UE’s usage setting is changed to data centric. The existing mechanisms does not enable the UE to know whether the MSC is connected to the MME (that it supports CSFB via the SGs link).This gives a hindrance to UE to switch to CSFB mode from SG-LTE mode in case of dual RF, or re-enable LTE in case of single RF (if it was previously disabled) when UE moves from one MSC which is not connected to MME to another MSC which is connected to the MME.

Therefore, there requires a method for Single RF capable device in which a UE can regain LTE services without involving any user action and can utilize its CSFB capability (perform MO/MT voice call remaining in LTE) when moving from non CSFB- areas to CSFB areas.

Further, a method for Dual RF capable device in which a UE effectively switches between single RF (CSFB) and Dual RF (e.g. SG-LTE) which will significantly reduce battery consumption and which will contribute to better user experience is needed. Also a method where UE can utilize its CSFB capability (perform MO/MT voice call remaining in LTE) in CSFB areas is required to overcome the disadvantages of the existing mechanisms.

SUMMARY OF THE INVENTION

The various embodiments herein provide a system and method for handling of LTE and voice services for single and dual RF supported devices. The method comprising the steps of sending a combined registration request message, by the user equipment, for at least one evolved packet system (EPS) service through a first radio access network to a communication network, receiving an EPS service registration accept message comprising an indicator that indicates that a circuit switched fall back (CSFB) is not supported, disabling the first radio access network on receiving the EPS service registration accept message and in response to the indicator that indicates that CSFB is not supported; and switching to a second radio access network when the user equipment has a voice centric setting and IMS voice is not available.

According to an embodiment herein, the method further comprises the steps of sending a request by the user equipment to the network, for registering for the PS and CS explicitly seeking SGs link related information from network; receiving a request accept message along with an indicator indicating a SGs link information from the network; and
switching to the first radio access network if the SGs link is present in the request accept message; and remaining in the second radio access network if the SGs link is not present.

According to an embodiment herein, the method of switching to the first radio access network if the SGs link is present in the request accept message comprises of broadcasting an information related to the SGs link, a timer value for re-enabling first radio access network based on network topology and UE’s movement, packet temporary mobile subscriber identity (P-TMSI) and IP Multi Media Subsystem (IMS) voice over packet switched (VoPS) indication to the user equipment by the network. (which are also key parameters for re-enabling first radio access technology and performing combined registration/update).

According to an embodiment herein, the method further comprises of broadcasting an information related to the SGs link, a timer value for re-enabling first radio access network based on network topology and UE’s movement, packet temporary mobile subscriber identity (P-TMSI) and IP Multi Media Subsystem (IMS) voice over packet switched (VoPS) indication to the user equipment by the network (which are also key parameters for re-enabling first radio access technology and performing combined registration/update).

According to an embodiment herein, the method further comprises storing, by the user equipment, mobility management entity (MME) IDs received in the registration accept message sent from the network in a memory of the user equipment.

According to an embodiment herein, the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

According to an embodiment herein, the second radio access network is one of a Universal Terrestrial Radio Access Network (UTRAN), or GPRS EDGE Radio Access Network (GERAN).

According to an embodiment herein, the combined registration request message is at least one of an ATTACH request message or a TRACKING AREA UPDATE request message, along with an indicator to indicate that it is a combined registration request.

According to an embodiment herein, the indicator is a network feature support information element including a SGs bit along with neighbor TA list information with necessary configuration (e.g. availability of voice domain, Vo-PS support etc.).

According to an embodiment herein, the method further comprises storing, by a user equipment, a neighbor TAI list with supported feature based on the TAU/Attach accept message received from the network in a memory of the user equipment.

According to another embodiment herein, the present invention provides a method for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported user equipments. The method comprises sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network; receiving an EPS service registration accept message comprising an indicator that indicates that circuit switched fall back (CSFB) is not supported; and remaining in the current radio access network; when the user equipment has a data centric usage setting.

According to another embodiment herein, the present invention provides a method of handling LTE and voice services for user equipment with voice centric usage settings. The method comprises the steps of sending a combined registration request message for at least one evolved packet system (EPS) service via a first radio access network; verifying if the combined registration request is accepted for the EPS with reject cause “CS domain not available”; disabling the first radio access network and sending a registration request to a second radio access network if the combined registration request is accepted only for the EPS with reject cause “CS domain not available”; checking if the registration request for the second radio access network is successful; remaining in the second radio access network if the registration accept/reject message comprising an indicator that indicates that SGs link is not available; enabling the first radio access network on receiving a combined registration accept/reject message comprising an indicator that indicates that SGs link is available; and acquiring the CSFB services by sending the combined registration request.

According to another embodiment herein, the method of handling LTE and voice services for a user equipment with voice centric usage settings further comprises enabling the first radio access network if the second radio access network is not found;
remaining on a same PLMN (if no other PLMN found); and sending a update registering request for the EPS service including SGs link information required bit; on receiving an EPS service registration accept message comprising an indicator that indicates that the circuit switched fall back (CSFB) is supported for the same PLMN the CSFB services are acquired by sending the combined registration request.

According to another embodiment herein, the method of handling LTE and voice services for a user equipment with voice centric usage settings further comprises verifying if the combined registration request message is rejected with cause 18; disabling the first radio access network if the combined registration request is rejected; and switching to the second radio access network if IMS voice is not available.

According to another embodiment herein, the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

According to an embodiment herein, the second radio access network is one of a Universal Terrestrial Radio Access Network (UTRAN), or GPRS EDGE Radio Access Network (GERAN).

According to another embodiment herein, the combined registration request message is at least one of an ATTACH request message or a ROUTING AREA UPDATE request message, along with an indicator to indicate that it is a combined registration request and with a SGs link information required bit.

According to another embodiment herein, the user equipment with voice centric usage settings is a single RF device with CS/PS Mode1.

According to a further embodiment, the present invention provides a method of handling LTE and voice services for user equipment with data centric usage settings. The method comprises the steps of sending a combined registration request message for at least one evolved packet system (EPS) service through a first radio access network; verifying if the combined registration request is accepted for the EPS with reject cause “CS domain not available” ; remaining on a PLMN associated with the first radio access network if the combined registration request is accepted only for the EPS with the reject cause 18 ; and sending a update registering request for the EPS service including SGs link information required bit; acquire the CSFB services by sending the combined registration request upon receiving an EPS service registration accept message comprising an indicator that indicates that the SGs link is available.

According to an embodiment herein, the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

According to the further embodiment, the indicator is a SGs link bit value present in the network feature support IE.

According to the further embodiment, the user equipment with data centric usage settings is a single RF device with CS/PS Mode2.

According to a further embodiment, the present invention provides a method of handling data service and voice service for a user equipment with voice centric usage settings. The method comprising the steps of enabling a first radio access network having a first radio frequency for a dual RF device; sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network; verifying if the combined registration request is accepted for the EPS with reject cause 18; and switching the UE to PS Mode 1 on RF1 with the first radio access network and enabling chip 2 with RF 2 to latch to the second radio access network; and further performing an action based on an accept message for the registration request.

According to the further embodiment, the method of performing an action based on the response of the combined registration request comprises of verifying if the accept message for the combined registration request indicates the presence of an SGs link with the first access network on the first radio access frequency; switching to a dual RF configuration for the UE if the SGs link is not present; and changing the device to PS mode; acquiring data services from the first access network using the first radio access frequency.
According to the further embodiment, the method of performing an action based on the response of the combined registration request further comprises verifying if the accept message for the combined registration request indicates the presence of an SGs link with the second access network on the RF2; switching to a dual RF configuration for the UE if the SGs link is not present; and changing the device to PS mode; acquiring voice services from the second access network using the second radio access frequency.

According to the further embodiment, the method of handling data service and voice service for a user equipment with voice centric usage settings further comprises receiving a detach request message with type “re-attach required” sent by the network when the SGs link is present; and switching to the first access network upon receiving the SGs link present indication in the subsequent registration accept message on the second radio access network

According to another embodiment herein, the first radio access is an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).

According to an embodiment herein, the second radio access network is one of a Universal Terrestrial Radio Access Network (UTRAN), or GPRS EDGE Radio Access Network (GERAN).

According to yet another embodiment, the present invention provides a method of handling of data services and voice services for dual RF user equipment with data centric usage settings. The method comprising the steps of enabling a first radio access network on the user equipment on RF1 on CHIP1; sending a combined registration request message for at least one evolved packet system (EPS) service through the first radio access network; verifying if the combined registration request is accepted for the EPS with reject cause 18; remaining on the same PLMN if no other PLMN belonging to the first radio access network is present; and enabling RF2 on CHIP2 with second radio access network for providing the voice service if required and disabling the RF2 on CHIP2 when acquiring the CSFB services using RF1 on CHIP1 by sending the combined registration request when the registration accept message indicates the presence of the SGs link for the PLMN for which reject cause 18 was received

According to yet another embodiment, the accept message further comprises a timer value, packet temporary mobile subscriber identity (P-TMSI) and IP Multi Media Subsystem (IMS) voice over packet switched (VoPS) bit (which are also key parameters for disabling RF2 and performing combined registration in first radio access network on RF1).

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 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 is a system diagram illustrating a CSFB supported and CSFB not supported environment for handling LTE and voice services for single and dual RF supported devices, according to an embodiment of the present invention.

FIGURE. 2 is a flow chart illustrating an exemplary method for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported user equipments, according to an embodiment of the present invention.

FIGURE. 3 is a flow chart illustrating an exemplary method of handling LTE and voice services for user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention.

FIGURE. 4 is a flow chart illustrating an exemplary method of handling LTE and voice services for user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention.

FIGURE. 5 is a flow chart illustrating an exemplary method of handling data service and voice service for a user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention.

FIGURE. 6 is a flow chart illustrating an exemplary method of handling of data services and voice services for dual RF user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention.

Figure 7 is a flow diagram illustrating a process of handling LTE and voice services for user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment.

Figure 8 is a flow diagram illustrating a process of handling LTE and voice services for user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention.

Figure 9 is a flow diagram illustrating a process of handling data service and voice service for a Dual RF supported user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention.

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 provides a system and method for handling of LTE and voice services for single and dual RF supported devices. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

FIG. 1 is a system diagram illustrating a CSFB supported and CSFB not supported environment for handling LTE and voice services for single and dual RF supported devices, according to an embodiment of the present invention. According to the 3GPP specification, when UE camps on the EPS network, users' basic voice services and the supplementary services based on the voice services are provided and controlled by either IMS or CSFB mechanism. The EPS system per se cannot provide and control voice call services over CS domain and can only provide transmission for IP data. However, during initial EPS network deployment, operators, without deploying an IMS, deploy EPS networks in key or hot spots where the GSM/UMTS coverage is also available as IMS network deployment is currently at a very nascent stage and not very popular as well. In this scenario, it is hoped that voice call services can be provided through and only through the CS domain of overlapped GSM/UMTS coverage. When the UE camps on the EPS network, the UE cannot camp on the GSM/UMTS network, since the UE is single radio. So the UE cannot receive CS service paging or initiate the CS service via the GSM/UMTS network when it is camped on the LTE, thus users are unable to execute voice calls, short messages and other CS services. In order to enable CS services in such scenario, 3GPP has set up a CS Fallback (CSFB) task to work out a solution. The current CSFB solution: SGs interface is introduced between MME and MSC/VLR. The SGs is extended based on the Gs interface. When the UE camps on the EPS network, the UE initiates CSFB attachment or combined TA (Tracking Area)/LA Update, and a SGs association is established between the MME and the MSC/VLR (i.e. the MME stores the MSC/VLR number or address information, and the MSC/VLR stores the MME number or address information). Subsequently, when the UE moves in the EPS network, the latest location information of the UE is updated to the MME. If location area or the MME changes, then the information stored in the MSC/VLR is updated, too.

According to Figure 1, consider that UE connected in a first cell, is registered via the SGs to a first MSC with a first Location Area Identity (LAI) wherein the first LAI is determined as mentioned in 3GPP TS29.118 section 5.2.2.2. Subsequently, the network node, such as an eNB, may determine that it is more appropriate to connect the UE to a target cell that is associated with a different, i.e. second, LAI and which also belongs to a respective second MSC. Such a scenario is discussed in 3GPP document S2-101441. In such a case, during the handover, the UE may enter a different PLMN. Alternatively, UE may reselect to different cell that is associated with different LAI based on provision of desired services or based on signal strength. If the target MME is not connected to any MSC i.e. if SGs link is not present and IMS voice is also not available, then as per 3GPP TS24.301, voice centric UE will disable LTE and acquire 2G/3G for provision of voice services.
In such a scenario, where even if the UE enters from a non CSFB area to a CSFB area, UE cannot automatically receive the CSFB services. Consequently, single RF device remains in the 2G/3G even though UE could have received CSFB services and dual RF capable device cannot operate in single RF mode even though the same could have been possible. Therefore, the present invention provides a method for single RF UE to regain LTE services without any user action involved and to utilize its CSFB capability in CSFB areas and a method for dual RF UE to effectively switch between single RF (CSFB) and dual RF (e.g. SG LTE) which will significantly reduce power consumption.

Figure 2 is a flow chart illustrating an exemplary method for handling LTE and voice services for Circuit Switched Fall Back (CSFB) supported user equipments, according to an embodiment. According to Figure 2, at step 202, a combined registration request message is sent by a UE for at least one evolved packet system (EPS) service through a first radio access network to a communication network. the combined registration request message is at least one of a ATTACH request message or a TRACKING AREA UPDATE request message along with appropriate type to indicate that it is a combined registration request. The indicator received from network is a network feature support information element including a SGs bit along with neighbor TA list information with necessary configuration. (E.g. availability of voice domain, Vo-PS support and so on). The UE stores the neighbor TAI list with supported feature based on the TAU/Attach accept message received from the network in a memory of the user equipment.

At step 204, an EPS service accept message comprising an indicator that indicates that a circuit switched fall back (CSFB) is not supported is received from the communication network. The EPS service accept message also comprises of information relating to the MME id(s) (GUMMEI). The UE stores the MME id(s) (GUMMEI) received in the combined attach accept message sent from the network in a memory. At step 206, it is determined whether the UE has voice centric usage setting or data centric usage settings. If the UE has voice centric usage settings, then at step 208, the first radio access network is disabled upon receiving the EPS service registration accept message and in response to the indicator that indicates that CSFB and IMS voice is not supported. At step 210, the UE is switched to the second radio access network when the UE has a voice centric setting and IMS voice is not available. If the UE has data centric usage settings, then at step 220, the UE is remained in the current radio access network and further behaves as defined in 3GPP TS24.301. At step 212, a request for registering for the PS and CS explicitly seeking SGs link related information from the network is sent by the user equipment to the network. At step 214, a request accept message along with an indicator indicating SGs link information is received from the network.
At step 216, UE is switched to the first radio access network if the SGs link is present in the request accept message. In an alternate embodiment, the UE is switched to the first radio access network based on an information message broadcasted by the network. for example, consider that the network broadcasts a message comprising information relates to the SGs link, a timer value for re enabling first radio access network based on network topology and UE’s movement, packet temporary mobile subscriber entity (P-TMSI) and IP Multimedia Sub-system voice over packet switched (VoPS) indication to the user equipment (which are also the key parameters for re-enabling first radio access technology and performing combined registration/update). Now, based on this information alone, the UE can switch to the first radio access network.
At step 218, UE is remained on the second radio access network if the SGS link is not present.

FIG. 3 is a flow chart illustrating an exemplary method of handling LTE and voice services for user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention. At step 302, a combined registration request message for at least one evolved packet system (EPS) service is sent via a first radio access network to the new MME. The combined registration request message on First Radio Access Network is at least one of an ATTACH request message or a TRACKING AREA UPDATE request message, along with an indicator indicating that it is a combined registration request message. The combined registration request message on Second Radio Access Network is at least one of an ATTACH request message or a ROUTING AREA UPDATE request message or Location Area Update Request message. At step 304, it is verified whether the combined registration request (TAU/Attach) is accepted for both EPS and Non-EPS Services or not. If the combined registration request is accepted only for EPS Services with reject cause 18, then at step 306, the first radio access network is disabled and a registration request is sent to a second radio access network if IMS voice is not available. If the combined registration request with Second Radio Access Network is not accepted, then normal 3GPP procedure is carried out. In an embodiment, the network also sends a timer value along with the LAU accept message for the CS. The timer value is based on the network topology and UE’s movement. In such a case, the UE disables the LTE (first radio access network) for the duration mentioned in the LAU accept message and re enable LTE and try combined registration of the camped registration area (TA) supports CSFB or UE is VoLTE capable and camped TA provides VoLTE services.

At step 308, it is checked whether the registration request for the second radio access network is successful. If the registration request for the second radio access network is successful, then at step 310, it is checked whether SGs link presence information is indicated in the registration accept message. If the SGs link presence information is indicated in the registration accept message, then at step 312, the first radio access network is enabled on receiving an registration accept/reject message comprising an indicator that indicates that an SGs link is available. If not, then at step 330, the UE is remained in the second access network if the registrations accept/reject message comprises an indicator that indicates that CSFB is not supported. The UE with voice centric usage setting is a single RF device with CS/PS Mode 1.

At step 314, CSFB services are acquired by sending the combined registration request message on First Radio Access Network. At step 316, the first radio access network is enabled if the second radio access network is not found. At step 318, UE is remained on the same PLMN if no other PLMN is found. At step 320, an update registration request is sent for EPS service including SGs link information required bit. At step 322, UE received an EPS service registration accept message comprising an indicator that indicates that the SGs link is not present (CSFB is supported for the same PLMN). At step 324, SCFB services are acquired by sending the combined registration request message. At step 326, it is verified whether the combined registration request message is rejected with cause 18. If the combined registration request message is rejected with cause 18 and IMS voice is verified to be not available at step 332, then the first radio access network is disabled and the UE is switched to the second radio access network. If the combined registration request message is not rejected with cause 18 or IMS voice is found available, then at step 328, normal 3GPP procedure is followed.

In an exemplary embodiment, the first radio access network (i.e. LTE) is temporarily disabled when RAU/LAU/Attach accept message indicates that there is no SG link present and LTE is re-enabled when the RAU/LAU/Attach accept message for the PLMN for which reject cause #18 was received indicates the presence of SGs link. When the network sends the combined attach accept message (RAU/Attach accept message) with the network feature IE indicating the presence of SG link, then the network also sends a packet temporary mobile subscriber identity (P-TMSI) to the UE so that the mapped GUMMEI derived from the P-TMSI provided in the RRC connection setup complete message helps e-Node B to route initial NAS message (Attach request/TAU request) to the MME which has got SGs link present. This can be extended to VoLTE support indication in that area.

According to an embodiment of the present invention, a single RF UE operating as CS/PS mode 1 enables LTE on receiving SGs link indication in the registration accept message. This is applicable to the VoLTE supported UE which enables LTE on receiving VoLTE support indication in the registration accept message.

According to an embodiment of the present invention, UE uses a GUMME ID provided in the LAU Accept message in GSM/UMTS networks along with an indication that SGs link is present.

According to another embodiment, a network operating in NMO1, initiates a detach with detach type set to “IMSI Detach” or “detach with reattach needed” when it finds SGs link between MSC and MME. The network then indicates the presence of SGs link in the LAU/Attach accept message so that the UE can re-enable LTE.

FIG. 4 is a flow chart illustrating an exemplary method of handling LTE and voice services for user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention. At step 402, a combined registration request message is sent for at least one evolved packet system service via a first radio access network. At step 404, it is verified whether the combined registration request message is accepted for the EPS with reject cause 18. At step 406, the UE is remained on a PLMN associated with the first radio access network if the combined registration request is accepted only for the EPS with reject cause 18. The UE with data centric usage settings is a single RF device with CS/PS Mode 2. At step 408, an update registration request for the EPS service is sent. At step 410, CSFB services are acquired by sending combined registration request message upon receiving an EPS service registration accept message comprising an indicator that indicates that a SGs link is present (CSFB is supported for the same PLMN). The indicator is an SG link bit value present in the network feature support IE.

According to an embodiment, in case a network is operating in NMO2 and when the UE tries the periodic LAU/RAU then the network indicates the presence of SGs link in network feature IE with the LAU/RAU accept message so that the UE can re-enable LTE.

FIG. 5 is a flow chart illustrating an exemplary method of handling data service and voice service for a user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention. At step 502, first radio access network having first radio frequency (RF1) is enabled for a dual RF device. At step 504, a combined registration request message for at least one EPS service is sent through the first radio access network. At step 506, it is verified whether the combined registration request message is accepted for the EPS with reject cause 18. At step 508, the UE is switched to CHIP 2 with RF 2 with the first radio access network where the UE is in PS MODE 1 on RF 1 and to a second radio access network on RF 2 if the combined ATTACH/TAU is accepted only for the EPS service with a reject cause 18 and IMS voice not available. The term reject cause 18 and “CS domain not available” can be used interchangeably. At step 510, an action is performed based on an accept message for the combined registration request.

One of the action is that at step 512, it is verified whether the accept message for the Location Update Request indicates the presence of a SGs link with the second access network on the RF 2. At step 514, the UE remained on dual RF configuration for the UE if the SGs link is not present. At step 516, the device is changed to PS mode. At step 518, data services are acquired from the first access network using the RF 1 and voice services from second access network using RF2.

Another action is that at step 520, it is verified whether the accept message for the update registration request indicates the presence of a SGs link with the first access network on the RF 1. At step 522, the UE remained in dual RF configuration for the UE if the SGs link is not present. At step 524, the device is changed to PS mode. At step 526, voice services are acquired from the second access network using the RF 2 and data services from first radio access network using RF1.

In an exemplary embodiment of the present invention, a dual RF UE operating as CS/PS mode 1 switches the mode to PS mode 1 after enabling dual RF instead of disabling the LTE for the PLMN where the TAU/Attach was accepted for EPS only with EMM cause #18. Then, the UE changes the mode back to CS/PS mode 1 after enabling single RF whenever SGs link is indicated in network feature support in TAU/Attach accept or Lau/RAU/Attach (GERAN/UTRAN) accept message for the PLMN (Dual RF to single RF switching). In case of VoLTE supported UE in dual RF mode, UE disables second RF when it moves from Non CSFB and Non VoLTE area to Non CSFB VoLTE area. UE enables second RF when it moves from Non CSFB VOLTE area to Non CSFB and Non VoLTE area.

Further, if the combined registration is successful, mode of the UE is changed to CS/PS 1 and other RF is switched off to save the battery.

FIG. 6 is a flow chart illustrating an exemplary method of handling of data services and voice services for dual RF user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention. At step 602, a first radio access network is enabled on the UE. At step 604, a combined registration request message for at least one EPS service through first radio access network. At step 606, it is verified whether the combined registration request message is accepted for the EPS with reject cause 18 and IMS voice is not available. At step 608, the UE is remained on the same PLMN if no other PLMN is present. At step 610, an update registration request for the EPS service is sent with SGs info required bit set to TRUE if the combined registration request was accepted only for the EPS with a reject cause 18 and IMS voice was not available. At step 612, CSFB services are acquired by sending combined registration request message when the registration accept message indicates the presence of SGs link for the PLMN for which reject cause 18 was received. The accept message further comprises a timer value, IP Multimedia Subsystem (IMS) voice over packet switched (VoPS) bit (which are also key parameters for sending combined registration in first radio access network. It is user’s choice if for data centric UE in dual RF configuration, user wants voice services from second radio access network upon receipt of combined registration accept only for EPS Services with reject cause 18. In this case upon re-acquisition of CSFB services upon receipt of LAU accept message comprises a timer value, appropriate P-TMSI and IP Multimedia Subsystem (IMS) voice over packet switched (VoPS) indication bit UE shall disable RF2.

Figure 7 is a flow diagram illustrating a process of handling LTE and voice services for user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment. Consider that the UE boots up with the first radio access network. The first radio access network is an Evolved UMTS Terrestrial Radio Access Network (E UTRAN) say LTE. Initially, the UE sends a combined registration request (ATTACH/TAU) to a new MME through the eNode B of the LTE. Now, when the new MME receives this combined registration request, it checks whether there is a SG link present between the new MME and the MSC. Consider that there is no SGs link present between the new MME and the MSC, then the new MME sends a ATTACH/TAU accept message for EPS only and #18 “CS domain not available”. When the UE receives this accept message with CS domain not available, then the UE checks for the VoPS bit present in the accept message in Network Feature Support IE which indicates if IMS voice is available. If the UE finds that the VoPs bit is equal to zero then, the UE sets the SGs link required bit present in the LAU request message to one. Subsequently, the UE disables the E-UTRAN and initiates a combined registration procedure with a second radio access network. The second radio access network is one of a UTRAN; global system for mobile communications (GSM) enhanced data rates for GSM evolution (EDGE) radio access network (GERAN), for e.g. 2G/3G systems.

Figure 8 is a flow diagram illustrating a process of handling LTE and voice services for user equipment with data centric usage settings in CS/PS mode 2, according to an embodiment of the present invention. Consider a UE with data centric usage setting in CS/PS mode 2. In such a case, the UE searches for other PLMNs to register when it receives a “reject cause 18 CS domain not available” in the ATTACH/TAU accept message with the first radio access network, say LTE. When no other PLMN is found to be present, then the UE sets the SGs link required bit to one and remains on the same PLMN. Then, the UE periodically sends a TAU request (only for EPS services with SGs link required bit) to the eNode B of the first access network. The new MME of the first radio access network checks for the SGs link availability upon receiving this request. When the new MME finds a SGs link present between the MME and the MSC, it sends a TAU accept message (EPS only) with SGs link present in network feature IE). The network feature indicates the UE the presence of the SGs link. Hence, UE performs a combined update in first radio access network i.e. LTE when it receives accept message with SGs link present indication.

Figure 9 is a flow diagram illustrating a process of handling data service and voice service for a user equipment with voice centric usage settings in CS/PS mode 1, according to an embodiment of the present invention. Consider a UE with data services and voice services in CS/PS mode 1. In such a case, the UE enables dual RF with LTE in PS mode 1 on RF 1 and GSM/UMTS on RF 2 for CS when the UE receives a “reject cause 18 CS domain not available” in the ATTACH/TAU accept message with the first radio access network, say LTE. Subsequently, the UE sends a update registration request on RF 1 for EPS only services with SG information required bit=1. Upon receiving this request, the network checks whether SGs link is present between the MME and the MSC. If the SGs link is present, then the network sends ATTACH accept message for EPS only and SGs link present indication with the network feature IE. The network feature indicates the UE the presence of the SGs link. In parallel UE sends a LAU request message on RF 2 with the SGs information required bit =1. Again, the network checks if the SG link is present and sends the accept message with “SGs link available” and with network feature IE if the SG link is present between the MME and the MSC. The network further adds the list of MMEs (GUMMEI) to which MSC is connected to upon detecting the SGs link. The UE checks for this SGs bit in the accept message and if this bit is equal to one then the UE enables the single RF configuration and change the mode to CS/PS. Later, the UE initiates the combined TAU/Attach procedure with the current PLMN and the process repeats.

According to an embodiment of the present invention, for a single RF UE, neighbor TA list with supported feature is maintained which is received in the Attach accept/TAU accept message. UE which does not support VoLTE does not camp to TA which does not provide CSFB services. VoLTE supported devices does not camp onto the TA which does not support CSFB and VoLTE. For a dual RF UE, neighbor TA list with supported feature is which is received in the Attach accept/TAU accept is maintained. UE which doesn’t support VoLTE will do combined registration(Attach/TAU) when it move to registration area which supports SGs and disable other RF. UE which support VoLTE will do IMS registration when move to registration area which supports VoLTE. After IMS registration is successful, UE can switch off other RF by sending IMSI detach indication (if supported in the network). The neighbor TAI list with supported feature in the registration accept message (VoLTE, IMS emergency service, SGs etc) is as below
TAI Feature bitmask
X 10000001
Y 10000001

The embodiments herein enable the UE to take an efficient decision on receiving the reject cause 18 “CS domain not available” in the registration accept message. The present invention also helps the UE to know whether the SG link between the MME and MSC is present or not to perform the combined attach or update procedure. The present invention also helps the UE to know when the configuration for CSFB support changes on the network side or when the UE moves from non CSFB supported areas to the CSFB supported area of the same PLMN. Further, the present invention also addresses the condition under which the Dual RF can be switched to Single RF Mode Configuration or vice versa, based on the trigger from the Network and accordingly UE mode of operations can be handled. Dual Mode configuration puts additional load on the Battery and efficient use of Dual RF Mode (by switching to single RF mode as proposed by this invention) will help in reducing the battery consumption. Hence, the present invention ensures that when UE moves from non CSFB to CSFB supported region on the same PLMN then UE can re-enable the LTE capabilities in contrary to the existing solution of power off/on or Airplane mode on/off or SIM card removal which enhances the user experience.

The present 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, firmware, and/or software embodied in a machine readable medium. Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.