System for providing voice service in a multimedia mobile network

The present invention relates to a multimedia network. In particular and without limitation, the present invention relates to systems and methods of providing voice services in multimedia mobile networks.

Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) is a third-generation (3G) technology for the wireless provision of multimedia services. With the development of Evolved UTRAN (eUTRAN), also known as Long Term Evolution (LTE) and Evolved Packet Core (EPC), multimedia telephone services for IMS, for example, It is necessary to shift the telephone service provided by MTSI: Multimedia Telephony Service for IMS) from a conventional circuit switched (CS) system to a packet switched (PS) system. This allows the Internet Protocol (IP: Internet) Protocol The Multimedia Subsystem (IMS) needs to be deployed faster and wider than eUTRAN and EPC.

<p> It would be advantageous to provide an architecture that allows the reuse of the CS core network infrastructure to support voice services during the deployment of eUTRAN and EPC.</p>

<p> In one aspect, the invention identifies voice service requirements for user equipment, recognizes support for Gs-based interfaces, and depending on voice service requirements, and for support for Gs-based interfaces. It relates to an advanced packet core network including a mobility management entity configured to redirect a user device to a circuit-switched cell in response to recognition.</p><p> From another aspect, the present invention receives a handover from a packet-switched cell to a circuit-switched cell, and performs a circuit-switched call establishment procedure with the circuit-switched cell when the handover procedure is completed. Concerning the mobile communication device configured in.</p><p> From yet another aspect, the present invention is configured to approve a handover instruction regarding the user equipment, obtain a measurement report about the user equipment, and hand over the user equipment to the circuit-switched cell indicated in the measurement report. Regarding eNodeB that has been done. The handover instruction is approved in response to the voice service request by the user device.</p><p> In yet another aspect, the present invention relates to a method by which a user device establishes a voice service. This method includes a step of receiving a handover command for handover from a packet-switched cell to a circuit-switched cell, and a step of establishing a circuit-switched call with the circuit-switched cell when the handover procedure is completed. ..</p><p> From yet another aspect, the present invention relates to a method of providing voice services to user equipment (UE) operating in a packet switching domain of an advanced universal mobile communication system terrestrial radio access network (eUTRAN) cell. .. In this method, a voice service between a UE and a circuit-switched cell in a circuit-switched domain is based on a step of generating a voice service requirement, a step of determining a circuit-switched cell, and the process of generating and the step of determining the circuit-switched cell. Including the process of establishing.</p><p> From yet another aspect, the present invention relates to a network including a plurality of circuit-switched cells and an evolved packet system (EPS). EPS includes multiple Evolved UTRAN cells (eUTRAN) and at least one Evolved Packet Core (EPC). The EPC is configured to hand over a user device (UE) operating in at least one eUTRAN cell to at least one circuit-switched cell, depending on voice service requirements.</p><p> From yet another aspect, the present invention is for an advanced packet core to establish a voice service, including a step of identifying voice service requirements and a step of performing a handover from a packet-switched cell to a circuit-switched cell. Regarding the method.</p>

In the following sections, the present invention will be described with reference to exemplary embodiments shown in the drawings.<figref num="1">It is a figure of the network used in one Embodiment of this invention.</figref><figref num="2">It is a flowchart of the method of providing a packet switching handover from an eUTRAN cell.</figref><figref num="3">The network interface shown in Figure 1 is shown.</figref><figref num="4">Shows the procedure for UE network registration.</figref><figref num="5">Indicates an incoming voice call.</figref>

Figure 1 shows an overview of network 10. The CS core network (CN) 11 includes a media gateway (MGW) 21 and a mobile switching center (MSC) 22. Other forms of the CS domain, such as the Home Location Register (HLR), are also expected to exist, but are omitted for clarity. The CS core network 11 is a public switched telephone network (PSTN) through a 2G / 3G Radio Access Network (RAN) cell, for example through GERAN (GSM / Edge Radio Access Network) or UTRAN14. Provides voice services from Network) 23 to user equipment (UE) 12. Network 10 also includes an advanced packet system (EPS) including eUTRAN 16 that provides PS services including voice via one or more eUTRAN cells. The PS service is provided from the packet data network 17 via the advanced packet core (EPC) network 18 including the service providing gateway 19 and the mobility management Entity (MME) 15. MME15 provides aspects of control, including location tracking of UEs in idle mode and paging procedures according to the eUTRAN standard.

In network 10 of FIG. 1, voice services may be provided to UE12 in the PS domain via the eUTRAN cell or to users in the CS domain via the GERAN / UTRAN cell. This is because the coverage areas provided by these cells are expected to have a very high degree of overlap. In this example, mobile station (MS: mobile) UE12, also known as station), is considered to be operating within an eUTRAN cell controlled by eUTRAN16 (also known as an LTE cell), which is one or more active packets that do not contain audio elements. There is no voice service in progress in the eUTRAN cell that has the service. If voice service is required, voice service could be established in the PS domain as a VoIP service in the current eUTRAN cell. However, if the eUTRAN service is gradually disseminated because the IMS service does not exist at the time of initial LTE introduction, there may be an eUTRAN coverage area where the GERAN / UTRAN coverage areas overlap. In these overlapping areas, domain transfer (DTF) associated with IMS service deployment as UE12 approaches the boundaries of eUTRAN coverage. It may not be possible to continue the voice service initiated in the eUTRAN cell due to the lack of function). As such, attempting to establish a voice call within an eUTRAN cell when IMS is not supported will result in these calls being cut off when the UE attempts to leave the LTE coverage area. Will be. Instead, when voice service is desired, eUTRAN coverage is still available, but UE12 leaves the eUTRAN cell and UE attempts to take advantage of the overlapping coverage area of 2G (GERAN) or 3G (UTRAN) cells. In some cases, voice services can be established in the CS domain with 2G / 3G cells without fear of premature interruption as would be possible if established within the eUTRAN cell. This is because coverage of 2G / 3G cells is considered ubiquitous. Therefore, in one embodiment, the requirement to establish a voice service while the UE12 is in LTE coverage initiates the handover of the UE12 from the eUTRAN cell to the GERAN / UTRAN cell, in the GERAN / UTRAN cell. The desired voice service is established in the CS domain.

Here, a method of providing a voice service to a UE operating in a packet switching domain of an eUTRAN cell will be described with reference to the flowchart 100 of FIGS. 1 and 2. In step 101, the voice call call is received from the MSC22 of the CS core network 11 by the MME15 of the EPC18. MME15 forwards this call to eNodeB33 (see Figure 3) in the eUTRAN cell. This call that MME sends to eNodeB indicates that a voice call needs to be established in the CS domain. eNodeB33 knows one or more active PS services for UE12 and is therefore able to access the history of measurement reports for UE12 within eUTRAN16 (step 102). eNodeB33 utilizes the history of existing measurement reports to determine nearby GERAN / UTRAN cells that can be selected as candidates for PS handover (step 103) (ie, eNodeB33 selects candidate GERAN / UTRAN cells). You don't need to get a history of additional channel measurements from the UE before you do). When the eNodeB sends a call to the UE and receives a call response, it selects one of these nearby cells (step 104) and initiates the PS handover procedure (step 105). For indirect MT voice service requests, the MME uses a generic read procedure that does not indicate that the call it sends to eNodeB should perform an Inter-RAT PS handover to the GERAN / UTRAN cell. Use to start calling the UE. Upon receiving a service request from the UE (via eNodeB) in response to the intent of the call, the MME recognizes that an Inter RAT PS handover to GERAN / UTRAN is required and therefore GERAN for this UE. Inter-Rat PS to / UTRAN cell By instructing eNodeB to execute HO (that is, instead of performing call establishment procedures in the packet-switched domain), service requests can be answered. The eNodeB 33 then utilizes the history of existing measurement reports to determine nearby GERAN / UTRAN cells that can be selected as PS handover candidates, as in steps 103-105 above, for these nearby cells. Select one of them and start the PS handover procedure. In the handover procedure, a PS handover instruction addressed to the UE to the selected GERAN / UTRAN cell is transmitted to the UE 12. The PS Handover instruction contains a cause code (cause code) indicating that the MT CS domain voice call needs to be established. UE12 therefore reaches the GERAN / UTRAN cell 14 and utilizes it in the GERAN / UTRAN cell selected for the handover after the completion of the PS handover (ie, for non-voice services in progress in the LTE cell). (Radio resources are allocated), the UE will proceed immediately as if it had been called for a voice call within the CS domain. That is, UE12 sends a call response to MSC22. A CS domain voice service is then established between UE12 and GERAN / UTRAN14, like the legacy procedure for MT / MO call setup.

If both UE12 and GERAN / UTRAN14 do not support dual transfer mode, PS resources will be exhausted once the voice service is established within the CS domain. If both UE and GERAN / UTRAN14 support dual transfer mode, PS resources are held in parallel with the resources required for CS domain voice services. In the case of PS handover to a UTRAN cell, it can be considered as a logical equivalent of PS handover to a GERAN cell that supports dual transfer mode. This is because UTRAN essentially allows PS domain services and CS domain services to work in parallel.

In any case (if dual transfer mode is supported or not supported), to PS handover from the eUTRAN cell (ie to allocate the CS domain resources needed for voice services) It is not necessary to perform the subsequent in-cell handover. This is because CS domain resources are allocated within the target GERAN / UTRAN cell as part of the legacy MT and MO voice service establishment process. If dual transmit mode is not supported, the PS resources allocated by the target GERAN as part of the eUTRAN to GERAN handover procedure will be explicitly or implicitly released after the CS service is established. Is retained until.

If neither UE12 nor GERAN / UTRAN14 support dual transmit mode, or a set of active PS services in an eUTRAN cell emphasizes delay to the extent that PS handover for cell changes is strictly required. If not, UE12 or eUTRAN16 would still be able to initiate a PS handover to the GERAN / UTRAN cell to minimize the delay in establishing the desired voice service within the CS domain.

A block diagram showing the network interface is shown in Figure 3. The user device 12 has circuit-switched access through GERAN / UTRAN 14 that communicates with the CS core network 11 through the A / lu interface 28. UE12 also communicates with eNodeB 33 of eUTRAN16. The eUTRAN16 interfaces with the Advanced Packet Core (EPC) 18 through the S1 interface 29, known as 3GPP.

In a typical circuit-switched general packet radio service (GPRS) network, PS domain mobility management is performed by the Serving GPRS Support Node (SGSN), which provides CS domain location update information. A Gs interface is provided between the SGSN and the MSC to provide to the MSC. In the EPC network, mobility management is performed by the mobility management entity (MME) 15 of the advanced packet core (EPC) 18. Therefore, in order to maintain the mobility management function of the CS domain in the MSC server 22, the Gs interface (Gs-like"" is used between the MME15 of the EPC18 and the MSC server 22 of the CS core network 11. interface) 26 is provided. The Gs interface 26 is a procedure for updating the location of the CS domain (usually started in the GERAN cell during the PS handover procedure) so that CS call messages can be sent from the MSC server 22 to the MME15. Can be used for.

The existence of the Gs interface can be used as a trigger for the MME to decide when to perform a PS handover to the CS core network. For direct MT voice service requests, the MME indicates that an Inter-RAT PS handover to the GERAN / UTRAN cell should be performed (ie, instead of performing call establishment procedures in the packet-switched domain). It is possible to send the call to eNodeB, in which case eNodeB sends a signaling message to the UE that acts as the call. Upon receiving the response to this call, eNodeB utilizes the existing measurement history to instruct the UE to perform an Inter-RAT PS handover to the GERAN / UTRAN cell. For indirect MT voice service requests, the MME will make an Inter-RAT call to the GERAN / UTRAN cell that it sends to the eNodeB. Initiate a UE call using a generic call procedure that does not indicate that a PS handover should be performed (ie, the MME must actually verify that the UE is available in the eUTRAN cell). To do. When a service request from the UE is received (via eNodeB) in response to a call attempt and the UE finds that it supports a Gs-based interface to the MSC, the MME issues an Inter-RAT PS to the GERAN / UTRAN cell. Recognizing the need for a handover and therefore by instructing the eNodeB to perform an Inter-RAT PS HO to the GERAN / UTRAN cell for this UE (ie, the procedure for establishing a call in the packet-switched domain). It is possible to respond to service requests (instead of doing).

In another embodiment for the direct case, upon obtaining a call response from the UE (ie, confirming that the UE is in a particular E-UTRAN cell), the eNodeB initiates the PS handover procedure. Has authority and, as a result, sends a PS handover command to the UE. This is possible if the MME makes use of the calls it sends to eNodeB to effectively convey its knowledge of the existence of Gs-based interfaces.

Within a 3GPP CS domain, both Location Area (LA) and Service Area (SA) support CS services'control'for a variety of purposes, eg, based on geographic area. Is the basic concept of. Location and service area concepts can be essentially supported by EPC and / or by mapping between LTE tracking areas and 2G / 3G cell structures (ie LA and SA).

As mentioned earlier, ESP mobility management is provided through Mobility Management Entity (MME) 15. Figure 4 shows an example of mobility management with a special example of UE network registration. The UE has the identifiers needed to establish a CS voice service. The UE sends a registration request to eNodeB, so the UE is authenticated prior to MME registration. While operating within LTE coverage (ie, without the need to establish a voice service), CS location updates are performed by the MME15 from the LTE tracking area (TA) to the location area (LA) for the MSC server 22. Can be started using the mapping to). The CS connection may be incorporated and the CS location update procedure is by the UE (present in the LA structure visible in the broadcast) or by the MME (based on the mapping from the LTE / SAE TA structure). Note that it is possible to get started. Once the base IP bearer is established, an identifier (eg LA) can be sent to the UE. The same concept can be used when the UE roams to other LTE coverage areas. That is, the LTE TA update procedure may include the CS position update procedure.

Before starting and transmitting the CS voice service, the UE is moved to the 2G / 3G cell using PS handover. After arriving at the 2G / 3G cell, all subsequent call establishment signaling is the same as the 2G / 3G outgoing call, not including eUTRAN and EPC.

The processing of incoming calls when eUTRAN is active is shown in Figure 5. A call request 51 containing the International Mobile Subscriber Identity (IMSI) is generated on the MSC server 22 and sent to the MME 15. The MME15 sends a call request to the eNodeB 33 via the S1 interface, and a Radio Resource Control (RRC) connection is available to give the UE 12 a call notification. When the call notification is received in UE12, the UE may send only the call response (ie, does not include the measurement report information) to eNodeB33. As a result, the eNodeB starts transmitting the PS handover instruction to the UE 12 using the existing measurement report information (that is, MT). Direct case of CS domain voice service establishment). The UE is moved to the 2G / 3G cell (using PS handover) prior to call establishment signaling. After arriving at the 2G / 3G cell, all subsequent call establishment signaling is the same as used for legacy mode operation, where the UE utilizes 2G / 3G, for example, Node B52 and wireless network controller 53. A 2G / 3G incoming call is initiated when the cell provides the service.

As will be apparent to those skilled in the art, the embodiments described herein utilize existing 2G / 3G mechanisms. However, no new protocol is needed as it has no impact on 2G / 3GRAN and the level of impact on the 2G / 3G core network is not serious.

The embodiments described herein are as cost-effective gap fillers (gap fillers) for providing CS voice services that give operators a little time to transition to MTSI when deploying eUTRAN. Can be understood.

The terms and descriptors used herein follow the standards used in the 3GPP standard for advanced packet systems and long-term evolution. Descriptions of features, interfaces and performance that are not part of the innovative concept are omitted for clarity.

As will be appreciated by those skilled in the art, the innovative concepts described herein can be modified and modified over a wide range of applications. Thus, the scope of the subject matter of a patented invention is not limited to any particular exemplary teaching discussed above, but is instead defined by the following claims.