Providing circuit switched operation in a wireless network

Abstract

In an evolved UMTS terrestrial radio access network (E-UTRAN), paging may be performed using an international mobile subscriber identity (IMSI) or S-temporary mobile subscriber identity (S-TMSI). With the paging, a wireless transmit/receive unit (WTRU) may send an extended service request message to the E-UTRAN and perform circuit switched (CS) fallback.

Claims

1. A mobility management entity (MME) comprising: a processor configured to receive, from a mobile switching center (MSC), a first page having a temporary mobile subscriber identity (TMSI) of a first wireless transmit/receive unit (WTRU); the processor configured to map the TMSI to an S-TMSI of the first WTRU; a transmitter configured to transmit, to the first WTRU in packet switched (PS) evolved UMTS terrestrial radio access network (E-UTRAN) signaling, a first paging message with the S-TMSI and a domain indicator that specifies the first paging message is associated with circuit switched (CS) service; the processor is further configured to receive, from the MSC, a second page having an international mobile subscriber identity (IMSI) of a second WTRU; the transmitter is further configured to transmit, to the second WTRU in PS E-UTRAN signaling, a second paging message with the IMSI of the second WTRU and a domain indicator that specifies that the second paging message is associated with a CS service; and a receiver configured to receive, in PS E-UTRAN signaling, extended service request messages from the first and second WTRUs associated with fallback to the CS service.

2. The method of claim 1 further comprising on the condition that the paging identity is the IMSI of the WTRU and a domain indicator in the page message is set to PS, detaching from the E-UTRAN by the WTRU prior to the reattaching to the E-UTRAN.

3. The method of claim 1 further comprising on the condition that the paging identity is the IMSI of the WTRU and the domain indicator in the page message is set to CS, sending a page response using the IMSI.

4. The method of claim 1 further comprising on a condition that the paging identity is an S-temporary mobile subscriber identifier, (S-TMSI) of the WTRU and the domain indicator in the page message is set to CS sending an extended service request message to the E-UTRAN and falling back to GSM or UMTS for a CS service.

5. A wireless transmit/receive unit (WTRU) comprising: a receiver configured to receive a page message from a mobility management entity (MME); a processor configured reattach to an evolved UMTS terrestrial radio access network (E-UTRAN) on a condition that a paging identity in the page message is an international mobile subscriber identifier (IMSI) of the WTRU and a domain indicator in the page message is set to packet switched (PS); and a processor further configured to send an extended service request message to the E-UTRAN and falling back to GSM or UMTS for a circuit switched (CS) service on a condition that the paging identity is the IMSI of the WTRU and the domain indicator in the page message is set to CS.

6. A method performed by a mobility management entity (MME), the method comprising: receiving, from a mobile switching center (MSC) by the MME, a first page having a temporary mobile subscriber identity (TMSI) of a first wireless transmit/receive unit (WTRU); mapping, by the MME, the TMSI to an S-TMSI of the first WTRU; transmitting, by the MME to the first WTRU in packet switched (PS) evolved UMTS terrestrial radio access network (E-UTRAN) signaling, a first paging message with the S-TMSI and a domain indicator that specifies the first paging message is associated with circuit switched (CS) service; receiving, by the MME from the MSC, a second page having an international mobile subscriber identity (IMSI) of a second WTRU; transmitting, by the MME to the second WTRU in PS E-UTRAN signaling, a second paging message with the IMSI of the second WTRU and a domain indicator that specifies that the second paging message is associated with a CS service; and receiving, in PS E-UTRAN signaling, extended service request messages from the first and second WTRUs associated with fallback to the CS service.

7. The WTRU of claim 5 further comprising the processor further configured to send a page response using the IMSI.

8. The WTRU of claim 5 wherein on a condition that the paging identity is an S-temporary mobile subscriber identifier (S-TMSI) of the WTRU and the domain indicator in the page message is set to CS, the processor further configured to send an extended service request message to the E-UTRAN and falling back to GSM or UMTS for a CS service.

9. The method of claim 6, wherein the second WTRU remains attached to the MME at least until the extended service request message is received.

10. The method of claim 6, wherein the second paging message is responded to with the IMSI.

11. A computer-readable storage medium with stored instructions executable by a mobility management entity (MME) computer to cause paging, the instructions comprising: instructions to receive, from a mobile switching center (MSC), a first page having a temporary mobile subscriber identity (TMSI) of a first wireless transmit/receive unit (WTRU); instructions to map the TMSI to an S-TMSI of the first WTRU; instructions to transmit, to the first WTRU in packet switched (PS) evolved UMTS terrestrial radio access network (E-UTRAN) signaling, a first paging message with the S-TMSI and a domain indicator that specifies the first paging message is associated with circuit switched (CS) service; instructions to receive, from the MSC, a second page having an international mobile subscriber identity (IMSI) of a second WTRU; instructions to transmit, to the second WTRU in PS E-UTRAN signaling, a second paging message with the IMSI of the second WTRU and a domain indicator that specifies that the second paging message is associated with a CS service; and instructions to receive, in PS E-UTRAN signaling, extended service request messages from the first and second WTRUs associated with fallback to the CS service.

12. The computer-readable storage medium of claim 11, wherein the extended service request messages include cause values of a page response.

13. The computer-readable storage medium of claim 11 further comprising: instructions to transmit another paging message to the second WTRU in E-UTRAN signaling having the IMSI and a domain indicator for PS; and instructions to cause reattachment, in response to the transmitted domain indicator for PS, the second WTRU to the E-UTRAN.

14. The computer-readable storage medium of claim 11, wherein the second WTRU remains attached to the MME at least until the extended service request message is received.

15. The computer-readable storage medium of claim 11, wherein the second paging message is responded to with the IMSI.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is a signal diagram of an attach procedure for CS fallback;

(3) FIG. 2 is a signal diagram of a method for a WTRU terminating a call while in Idle mode;

(4) FIG. 3 is a signal diagram of the preparation phase of a MO call in active mode;

(5) FIG. 4 is a signal diagram of the execution phase of a MO call in active mode;

(6) FIG. 5 is a diagram of an example relationship between location areas and tracking areas;

(7) FIG. 6 shows an example wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and an evolved Node B (eNB);

(8) FIG. 7 is an example functional block diagram of a WTRU and the eNB of FIG. 6;

(9) FIG. 8 is a flowchart of a method for triggering a combined TAU/LAU procedure;

(10) FIG. 9 is a flowchart of another method for triggering a combined TAU/LAU procedure;

(11) FIG. 10 is a flowchart of a method for triggering a LAU procedure;

(12) FIG. 11 is a flowchart of a method for determining a paging identity for a WTRU;

(13) FIG. 12 is a flowchart of a second method for determining a paging identity for a WTRU;

(14) FIG. 13 is a flowchart of a third method for determining a paging identity for a WTRU; and

(15) FIG. 14 is a flowchart of a fourth method for determining a paging identity for a WTRU.

DETAILED DESCRIPTION

(16) When referred to hereafter, the term “wireless transmit/receive unit (WTRU)” includes, but is not limited to, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the term “base station” includes, but is not limited to, a Node B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.

(17) A person having ordinary skill in the art should understand that the method and apparatus provided herein are applicable to any access technology which uses circuit switched or packet switched data, such as 3GPP LTE, WCDMA, GSM, GPRS, Enhanced Data for GSM Evolution (EDGE), Code Division Multiple Access (CDMA) 2000 (and related technologies), and the IEEE 802 family of technologies, for example 802.11, 802.16, and WiMAX.

(18) FIG. 6 shows an example wireless communication system 600 including a plurality of WTRUs 610 and an eNB 620. As shown in FIG. 6, the WTRUs 610 are in communication with the eNB 620. It should be noted that, although an example configuration of WTRUs 610 and an eNB 620 is depicted in FIG. 6, any combination of wireless and wired devices may be included in the wireless communication system 600.

(19) FIG. 7 is an example functional block diagram 700 of a WTRU 610 and the eNB 620 of the wireless communication system 600 of FIG. 6. As shown in FIG. 7, the WTRU 610 is in communication with the eNB 620.

(20) In addition to the components that may be found in a typical WTRU, the WTRU 610 includes a processor 612, a receiver 614, a transmitter 616, and an antenna 618. The receiver 614 and the transmitter 616 are in communication with the processor 612. The antenna 618 is in communication with both the receiver 614 and the transmitter 616 to facilitate the transmission and reception of wireless data. The processor 612 is configured to perform a method of maintaining circuit switched continuity in an E-UTRAN.

(21) In addition to the components that may be found in a typical Node B, the Node B 620 includes a processor 622, a receiver 624, a transmitter 626, and an antenna 628. The receiver 624 and the transmitter 626 are in communication with the processor 622. The antenna 628 is in communication with both the receiver 624 and the transmitter 626 to facilitate the transmission and reception of wireless data. The processor 622 is configured to perform a method of maintaining circuit switched continuity in an E-UTRAN.

(22) Triggers for Performing a Combined TAU/LAU

(23) The following triggers for performing a combined tracking area update (TAU)/location area update (LAU) may be used individually or in any combination.

(24) System Information Indication

(25) The E-UTRAN system information may carry an indication of the LA of the surrounding CS network, such as GSM or UMTS. This information may, for example, be carried on E-UTRAN System Information Blocks, such as SIB1. The information may indicate whether the LA is valid for a GERAN network or a UTRAN network. This information may indicate to the WTRU whether a combined TAU/LAU procedure is required in this area.

(26) A WTRU that is currently in the E-UTRAN and in IDLE mode may initiate a combined TAU/LAU procedure when it detects a change in the LA broadcast by the System Information Block (SIB) in the E-UTRAN. FIG. 8 is a flowchart of a method 800 for triggering a combined TAU/LAU procedure. The method 800 begins with the WTRU receiving the LA of the surrounding CS network (step 802). A determination is made whether the WTRU is currently in the E-UTRAN (step 804). If the WTRU is not currently in the E-UTRAN, then the method terminates (step 806). If the WTRU is currently in the E-UTRAN, a determination is made whether the WTRU is in Idle mode (step 808). If the WTRU is not in Idle mode, then the method terminates (step 806). If the WTRU is in Idle mode, then a determination is made whether the WTRU has detected a change in the LA (step 810). If the WTRU has not detected a change in the LA, then the method terminates (step 806). If the WTRU has detected a change in the LA, then the WTRU initiates a combined TAU/LAU procedure (step 812) and the method terminates (step 806).

(27) Timer

(28) The MSC/VLR may assign a timer to the WTRU when it performs an IMSI Attach procedure or a LAU Request procedure over the E-UTRAN. The timer may continue running in the NAS, even if the Evolved Packet System Mobility Management (EMM) sub-layer is in EMM-Connected mode or in EMM-Idle mode, as long as the WTRU is registered in the EPS domain, the CS domain, or both. When the timer expires, the WTRU may initiate a combined TAU/LAU procedure.

(29) FIG. 9 is a flowchart of method 900 for triggering a combined TAU/LAU procedure. The method 900 begins with the WTRU performing an IMSI Attach procedure or a LAU Request procedure over the E-UTRAN (step 902). After one of these procedures is performed, a timer is set by the MSC/VLR (step 904). Once the timer expires (step 906), the WTRU initiates a combined TAU/LAU procedure (step 908) and the method terminates (step 910).

(30) Subscriber Identity Module (SIM) Card

(31) The MSC/VLR may inform the WTRU about a new LAI to be stored on the WTRU's SIM card via the MME without the WTRU initiating a LAU request. As an example, in connected mode, if the MME determines that the WTRU is in an area belonging to a different LAI than the last registered LA, it may initiate the LAU on behalf of the WTRU. When doing so, the MME sends the new LAI and IMSI to the WTRU. The WTRU identity may be the TMSI, in case the MME creates and holds an association between the WTRU IMSI and the TMSI. The network may then configure the WTRU with a new LAI (and optionally a new TMSI) in any NAS message.

(32) FIG. 10 is a flowchart of a method 1000 for triggering a LAU procedure. The method 1000 begins with the WTRU moving into an area with a new LAI (step 1002). The MME initiates an LAU procedure on behalf of the WTRU (step 1004). The MME sends the new LAI and new IMSI to the WTRU (step 1006) and the method terminates (step 1008).

(33) EPS/IMSI Attached

(34) If the WTRU is EPS/IMSI attached and detects a condition for triggering a TAU request, the WTRU combines the TAU request with a LAU request. One condition for triggering the TAU request is when the WTRU enters an area where the TAI is not in the list of TAs previously registered by the WTRU, meaning that the WTRU is entering a new area. When this occurs, the WTRU needs to perform a registration update, which is a combined TAU/LAU procedure.

(35) Paging Identity for the WTRU

(36) The following techniques for determining a paging identity for the WTRU may be used individually or in any combination.

(37) IMSI/TMSI Mapping

(38) The MME may keep a mapping between the IMSI, the TMSI (if allocated), and the corresponding S-TMSI. If the MSC/VLR initiates paging in E-UTRAN for MT services using the IMSI, the MME may map the IMSI to the corresponding S-TMSI. The MME may then page the WTRU in E-UTRAN using the S-TMSI and an indication on the page message of the cause value, such as CS service, CS fallback, MT CS call, MT Short Message Service (SMS), etc. If the WTRU detects that the page message is directed to an identity assigned by upper layers for the WTRU (a TMSI or an IMSI), it initiates an Extended Service Request message on the E-UTRAN network, and sets the cause value for the service request to page response. If the WTRU is re-directed (falls back) to GSM/UMTS CS, the WTRU sends a page response using the IMSI.

(39) FIG. 11 is a flowchart of a method 1100 for determining a paging identity for a WTRU. The MME maintains a mapping between the IMSI, the TMSI, and the S-TMSI (if assigned; step 1102). The MSC/VLR initiates paging of the WTRU in the E-UTRAN using the IMSI (step 1104). The MME maps the IMSI to the corresponding S-TMSI (step 1106). The MME pages the WTRU in the E-UTRAN using the S-TMSI and a cause value (step 1108). A determination is made at the WTRU whether the S-TMSI in the page message is the receiving WTRU's S-TMSI (step 1110). In one embodiment, the WTRU compares the S-TMSI in the page message with the S-TMSI stored at the WTRU, for example, on the Universal Subscriber Identity Module (USIM) card. If the S-TMSI in the page message is not the receiving WTRU's S-TMSI, meaning that the page message is not intended for the receiving WTRU, then the page message is discarded (step 1112) and the method terminates (step 1114).

(40) If the S-TMSI in the page message is the receiving WTRU's S-TMSI (step 1110), then the WTRU initiates an Extended Service Request message on the E-UTRAN (step 1116). The WTRU then falls back to GSM or UMTS for the CS service (step 1118). After completing the fall back to CS, the WTRU sends a page response message using the IMSI (step 1120) and the method terminates (step 1114).

(41) IMSI Paging

(42) If the MSC/VLR initiates paging in the E-UTRAN for MT services using the IMSI, the MME may page the WTRU in the E-UTRAN using the IMSI. If the WTRU detects that the cause for the page message is related to a CS service, for example, CS fallback, a MT CS call, MT SMS, a CS domain indicator, etc., it may not ignore the page request nor detach from the E-UTRAN, but instead initiates an Extended Service Request message on the E-UTRAN network, and sets the cause value for the service request to page response. If the WTRU is re-directed (falls back) to GSM/UMTS CS, the WTRU sends a page response using the IMSI.

(43) FIG. 12 is a flowchart of a method 1200 for determining a paging identity for a WTRU. The method 1200 begins with the MSC/VLR initiating paging of the WTRU in the E-UTRAN using the IMSI (step 1202). The MME pages the WTRU in the E-UTRAN using the IMSI (step 1204). The WTRU detects a cause value associated with the page message (step 1206) and determines whether the page message is related to a CS service (step 1208). The paging message includes a WTRU identifier (such as the IMSI) and a domain indicator (set to either CS or PS). If the page message is not related to a CS service, meaning that the domain indicator is set to PS, then the WTRU reattaches to the E-UTRAN (step 1210) and the method terminates (step 1212).

(44) If the page message is related to a CS service, meaning that the domain indicator is set to CS (step 1208), then the WTRU initiates an Extended Service Request message on the E-UTRAN (step 1214). The WTRU then falls back to GSM or UMTS for the CS service (step 1216). After completing the fall back to CS, the WTRU sends a page response message using the IMSI (step 1218) and the method terminates (step 1212).

(45) S-TMSI Paging

(46) The MME may keep a mapping between the IMSI, TMSI (if allocated), and the corresponding S-TMSI. If the MSC/VLR initiates paging in E-UTRAN for MT services using the TMSI, the MME map the TMSI to the corresponding S-TMSI. The MME then pages the WTRU in the E-UTRAN using the S-TMSI and includes an indication on the page message of the cause value, such as, CS service, CS fallback, a MT CS call, MT SMS, etc. If the WTRU detects that the page message is directed to an identity assigned by upper layers for the WTRU, it initiates an Extended Service Request message on the E-UTRAN network, and sets the cause value for the service request to page response. If the WTRU is re-directed (falls back) to GSM/UMTS CS, the WTRU sends a page response using the IMSI.

(47) FIG. 13 is a flowchart of a method 1300 for determining a paging identity for a WTRU. The MME maintains a mapping between the IMSI, the TMSI, and the S-TMSI (if assigned; step 1302). The MSC/VLR initiates paging of the WTRU in the E-UTRAN using the TMSI (step 1304). The MME maps the TMSI to the corresponding S-TMSI (step 1306). The MME pages the WTRU in the E-UTRAN using the S-TMSI and includes a cause value in the page message (step 1308). A determination is made at the WTRU whether the S-TMSI in the page message is the receiving WTRU's S-TMSI (step 1310). If the S-TMSI in the page message is not the receiving WTRU's S-TMSI, meaning that the page message is not intended for the receiving WTRU, then the page message is discarded (step 1312) and the method terminates (step 1314).

(48) If the S-TMSI in the page message is the receiving WTRU's S-TMSI (step 1310), then the WTRU initiates a Extended Service Request message on the E-UTRAN (step 1316). The WTRU then falls back to GSM or UMTS for the CS service (step 1318). After completing the fall back to CS, the WTRU sends a page response message using the IMSI (step 1320) and the method terminates (step 1314).

(49) IMSI Paging

(50) The MME may keep a mapping between the IMSI, TMSI (if allocated), and the corresponding S-TMSI. If the MSC/VLR initiates paging in E-UTRAN for MT services using the TMSI, the MME maps the TMSI to the corresponding S-TMSI. The MME then pages the WTRU in the E-UTRAN using the IMSI and includes an indication on the page message of the cause value, for example, CS service, CS fallback, a MT CS call, MT SMS, etc. If the WTRU detects that the page message is directed to an identity assigned by upper layers for the WTRU, it may not ignore the page request nor detach from E-UTRAN, but instead it initiates an Extended Service Request message on the E-UTRAN network, and sets the cause value for the service request to page response. When the WTRU is re-directed (falls back) to GSM/UMTS CS the WTRU sends a page response using the IMSI.

(51) FIG. 14 is a flowchart of a method 1400 for determining a paging identity for a WTRU. The MME maintains a mapping between the IMSI, the TMSI, and the S-TMSI (if assigned; step 1402). The MSC/VLR initiates paging of the WTRU in the E-UTRAN using the TMSI (step 1404). The MME maps the TMSI to the corresponding IMSI (step 1406). The MME pages the WTRU in the E-UTRAN using the IMSI and includes a cause value in the page message (step 1408). A determination is made at the WTRU whether the IMSI in the page message is the receiving WTRU's IMSI (step 1410). If the IMSI in the page message is not the receiving WTRU's IMSI, meaning that the page message is not intended for the receiving WTRU, then the page message is discarded (step 1412) and the method terminates (step 1414).

(52) If the IMSI in the page message is the receiving WTRU's IMSI (step 1410), then the WTRU initiates a Extended Service Request message on the E-UTRAN (step 1416). The WTRU then falls back to GSM or UMTS for the CS service (step 1418). After completing the fall back to CS, the WTRU sends a page response message using the IMSI (step 1420) and the method terminates (step 1414).

(53) Although features and elements are described above in particular combinations, each feature or element may be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).

(54) Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine.

(55) A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.