Background technology
The 2G/3G network can be regarded a kind of comprehensive covering as to a certain extent through for many years deployment.Along with System Architecture Evolution (System Architecture Evolution, SAE)/Long Term Evolution project (Long Term Evolution, SAE/LTE) development of internet technology, the SAE/LTE network-covered is to some cities and traffic hot zones, cause in present communication network, SAE/LTE network and 2G/3G network are also deposited.
At different network carrying mechanism, the speech business of mobile communication can be divided into following several classes:
The first kind be circuit switching (Circuit Switching, the CS) session service of territory carrying is as voice call;
Second class is packet switching (Packet Switching, PS) session service of territory carrying is also referred to as VoIP class business, by IP Multimedia System (IP Multimedia Subsystem, IMS) provide service quality (QoS) to guarantee, as the voice call of IP carrying.
The SAE/LTE network is as a kind of packet switching system, and speech business can only be transmitted in its PS territory carrying, and IMS controls speech business by IP-based network.And in the 2G/3G network, speech business generally all is to be carried on the CS territory.2G network in the described 2G/3G network is meant global system for mobile communications (Global System for Mobile communications, GSM)/general packet radio service (General Packet Radio Service, GPRS)/strengthen GSM evolution (the Enhanced Data Rate for GSM Evolution of data rate, EDGE) system, 3G network is meant that multiplexing (the WCDMA)/high-speed packet of Wideband Code Division Multiple Access (WCDMA) inserts (High Speed Packet Access, HSPA) system, and be meant the system that comprises the CS territory in the said system, the system that does not comprise the CS territory is not in this scope.
Calling user equipment (User Equipment, UE) in the call process, might cross over two networks, because the difference of load-bearing of mobile telecommunication business mechanism, cause moving out SAE/LTE network base station institute coverage as UE, when entering 2G/3G network base station overlay area, the interruption of IMS speech business may occur, thereby influence the continuity of user speech business.Can adopt the eMSC technical scheme to solve IMS speech business that is carried on the SAE/LTE network and the continuity problem that is carried on speech business between the CS territory at present.
As shown in Figure 1, UE1 is in the 2G/3G network, and UE2 is in the SAE/LTE network, for realizing the conversation of UE1 and UE2, user's face at the SAE/LTE network increases the node eMSC with mobile switching centre (MSC) function, and the speech business of the SAE/LTE network carrying is controlled by eMSC.This is equivalent to increase the CS territory at user's face of SAE/LTE.Speech business from the SAE/LTE network when switch in 2G/3G network C S territory, eMSC connects mobile management entity (MME) and also has the function of MME, receives the switching message from MME; Simultaneously, eMSC is connected and has the function of MSC with the MSC of 2G/3G network, and can finish the conversion of PS territory and CS territory switching message as gateway.
But existing technical scheme can only solve the problem that speech business is switched to the CS territory of 2G/3G network from the PS territory of SAE/LTE network, can't solve from the problem in the PS territory of the CS territory reverse switchback SAE/LTE network of 2G/3G network.
Summary of the invention
In view of this, the embodiment of the invention proposes the method that a kind of speech business is switched, and can realize the reverse switching of speech business from the 2G/3G network to the SAE/LTE network.This method comprises the steps:
The user equipment (UE) that carries out speech business is from System Architecture Evolution/when Long Term Evolution project SAE/LTE network switches to the circuit switching (CS) territory of 2G/3G network, the eMSC of evolution mobile switching centre preserves the context of described UE in SAE/LTE network packet exchange PS territory, if the context in described PS territory limits if having time, then remove this time restriction;
The described UE that preserves according to described eMSC is at the context of SAE/LTE network PS field, and described speech business is switched to the SAE/LTE network from the CS territory of 2G/3G network.
The embodiment of the invention also proposes a kind of evolution eMSC of mobile switching centre, comprising:
The MME interactive module is used for UE receiving the handoff request from MME when the SAE/LTE network switches to the 2G/3G network, and described handoff request is carried the context of UE at the SAE/LTE network PS field; UE in the described handoff request is sent to memory module at the context of SAE/LTE network PS field;
Described memory module is used to store the context of UE at the SAE/LTE network PS field, if the context in described PS territory limits if having time, then removes this time restriction;
The MSC interactive module is used for UE is returned when switching to the SAE/LTE network from the 2G/3G network, receive from MSC handoff request, indicate described MME interactive module to send handoff request to MME;
Described MME interactive module also is used for UE is returned when switching to the SAE/LTE network from the 2G/3G network, according to the indication from described MSC interactive module, the UE in the described memory module is carried at the context of SAE/LTE network PS field sends to MME in the handoff request.
The network system that the embodiment of the invention also proposes a kind of SAE/LTE network and 2G/3G network and deposits comprises the MSC in the 2G/3G network, the MME and the e-NB of SAE/LTE network, and carries out the mutual eMSC of evolution mobile switching centre respectively with described MME and MSC;
Described eMSC is used for UE when the SAE/LTE network switches to the 2G/3G network, reception from described MME handoff request, preserve the UE that carries in the described handoff request context,, then remove this time restriction if the context in described PS territory limits if having time at the SAE/LTE network PS field; UE is returned when switching to the SAE/TE network from the 2G/3G network, receive handoff request, the UE that preserved is carried at the context of SAE/LTE network PS field sends to described MME in the handoff request from described MSC;
The handoff request from eMSC that described MME is used for being received is transmitted to e-NB;
Described e-NB is used for the context at the SAE/LTE network PS field according to the UE of the handoff request of being received, carries out the operation of UE from 2G/3G network insertion SAE/LTE network.
As can be seen from the above technical solutions, when the SAE/LTE network switched to the 2G/3G network, eMSC preserved the PS context of UE in this locality, when speech business oppositely switches to the SAE/LTE network at UE, the PS context is sent to MME, guarantee the correct execution of oppositely switching.
Embodiment
Based on the conventional eMSC technical scheme, guarantee that at first eMSC self can independently finish the function that existing scheme provides.On this basis, no matter be to switch to 2G/3G from SAE/LTE, still switch to SAE/LTE from 2G/3G, eMSC is the anchor point that switches all the time.In order to guarantee to return when cutting from 2G/3G, still can keep the PS context, can speech business from the SAE/LTE network when the 2G/3G network switches, MME sends normal PS switching command to eMSC, eMSC is kept at this locality with the PS context after receiving this order.Some PS is contextual to be preserved the time limit, packet data protocol (Packet Data Protocol for example, PDP) the overtime meeting of context is by deexcitation, therefore eMSC is when preserving the PS context, should ignore all relevant timers, the PS context is retained in this locality always, switches to the SAE/LTE network to returning.
Here the eMSC of indication is a logic entity, and it can be eMSC physically, also can be other physical node that links to each other with eMSC, with eMSC or realize above-mentioned functions separately.
For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is further elaborated below in conjunction with accompanying drawing.
The speech business that Figure 2 shows that the embodiment of the invention comprises the steps: from the handoff procedure of SAE/LTE network to 2G/3G network C S territory
Step 201:UE sends measurement report (Measurement report) to the evolved base station (e-NB) of SAE/LTE network;
Step 202:e-NB is according to described measurement report, and judgement UE switches, and sends handoff request (Relocation required) to MME;
Step 203:MME is transmitted to eMSC with described handoff request, comprises the context of UE at the SAE/LTE network PS field in this request;
Step 204:eMSC preserves the PS territory context of described UE, if described PS territory context limits if having time, then remove this time restriction, be about to this contextual timer in PS territory and be set to invalidly, and send MAP to the MSC of 2G/3G network and prepare handoff request (MAP prepare handover request);
Step 205:MSC sends handoff request to base station controller (BSC);
Access network resource reservation procedure (RAN resource reservation) is carried out in step 206:BSC and base station (BTS), for UE in the corresponding resource of 2G/3G network allocation;
Step 207:BSC sends switching response message (handover request ACK) to MSC;
Step 208:MSC sends MAP to eMSC and prepares handoff response (MAP prepare handover response).
Step 209:eMSC sends initial address message (IAM) to MSC;
Step 210:MSC sends Address Complete Message (ACM) to eMSC
Step 211:eMSC connects user's face.
Through behind the above-mentioned handoff procedure, UE inserts the CS territory of 2G/3G network, and keeps the context of this UE in the PS territory of SAE/LTE network among the eMSC.In this case, if UE goes back to the PS territory that switches to SAE/LTE again, then carry out flow process as shown in Figure 3:
Step 301:UE connects the cycle to the BSC reporting measurement reports by the signaling in CS territory;
Step 302 is switched to SAE/LTE according to the measurement report judgement UE of UE to 303:BSC, and then to MSC transmission handoff request, MSC is transmitted to eMSC with this handoff request.
Step 304 sends handoff request to MME to 305:eMSC, carries the PS territory context of the described UE that eMSC preserves in this locality in this handoff request.MME sends handoff request according to the PS territory context of described UE to e-NB, and indication e-NB carries out the resource reservation process.
Step 306:e-NB carries out the resource reservation process according to the handoff request of being received, for UE at the corresponding Internet resources of SAE/LTE network allocation.
Step 307 sends switching request response to 308:e-NB to MME, and MME is transmitted to eMSC with described switching request response.
Step 309:eMSC sends switching request response to MSC.
Step 310 sends switching command (handover command) to 311:MSC to BSC, and BSC is transmitted to UE with described switching command.
Step 312:UE initiates to switch the request of access to e-NB.
Step 313:e-NB sends to switch to MME and surveys (handover detect), and this UE is linked in the Internet resources of being reserved;
Step 314 sends handoff completion message to 315:e-NB to MME, and MME is transmitted to eMSC with described handoff completion message;
Step 316:eMSC deletes the PS territory context of the UE corresponding with described handoff completion message that is preserved, and returns handoff completion message to MME.
Step 317:eMSC sends end signal request (End signal req) to MSC;
Step 318:MSC and BSC carry out the resource dispose procedure, discharge the Internet resources that described UE takies in the 2G/3G network;
Step 319 sends to the SAE gateway to 320:MME upgrades the session management context request, and SAE returns to MME and upgrades the contextual response of session management.
The embodiment of the invention also proposes a kind of evolution eMSC of mobile switching centre, is used to control the speech business of SAE/LTE network, its structure as shown in Figure 4, described eMSC comprises:
MME interactive module 401 is used for carrying out alternately with the MME of SAE/LTE network;
MSC interactive module 402 is used for carrying out alternately with the MSC of 2G/3G network;
Memory module 403 is used to store the context of UE at the SAE/LTE network PS field;
Described MSC interactive module 402 is used for UE is returned when switching to the SAE/LTE network from the 2G/3G network, receive from MSC handoff request, indicate described MME interactive module 401 to send handoff request to MME;
;
Described MME interactive module 401 is used for UE receiving the handoff request from MME when the SAE/LTE network switches to the 2G/3G network, and described handoff request is carried the context of UE at the SAE/LTE network PS field; UE in the described handoff request is sent to memory module 403 at the context of SAE/LTE network PS field; UE is returned when switching to the SAE/LTE network from the 2G/3G network,, the UE in the described memory module is carried at the context of SAE/LTE network PS field sends to MME in the handoff request according to indication from described MSC interactive module 402.
Described eMSC can further include:
Timer failed module 404, be used for UE that memory module 403 stored be set at the contextual timer of SAE/LTE network PS field invalid.
Described eMSC can also comprise removing module 405, be used for UE is returned when switching to the SAE/LTE network from the 2G/3G network, after described MME interactive module 401 is received handoff completion message from MME, delete the described UE that preserves in the described memory module 403 context at the SAE/LTE network PS field.
The network system that the embodiment of the invention proposes a kind of SAE/LTE network and 2G/3G network and deposits comprises the MSC in the 2G/3G network, the MME and the e-NB of SAE/LTE network, and carries out mutual eMSC respectively with described MME and MSC,
Described eMSC is used for UE when the SAE/LTE network switches to the 2G/3G network, receive from described MME handoff request, preserve the UE that carries in the described handoff request context at the SAE/LTE network PS field; UE is returned when switching to the SAE/TE network from the 2G/3G network, receive handoff request, the UE that preserved is carried at the context of SAE/LTE network PS field sends to described MME in the handoff request from described MSC;
The handoff request from eMSC that described MME is used for being received is transmitted to e-NB;
Described e-NB is used for the context at the SAE/LTE network PS field according to the UE of the handoff request of being received, carries out the operation of UE from 2G/3G network insertion SAE/LTE network.
Described e-NB also is used for sending handoff completion message carrying out UE after the 2G/3G network returns the operation that switches to the SAE/LTE network to described MME;
Described MME is transmitted to eMSC with the handoff completion message of being received from described e-NB;
EMSC is according to described handoff completion message, and the UE that deletion is preserved is at the context of SAE/LTE network PS field.
Embodiment of the invention scheme can be achieved as follows technique effect: when the SAE/LTE network switched to the 2G/3G network, eMSC preserved the PS context of UE in this locality at UE; When UE again when the 2G/3G network oppositely switches to the SAE/LTE network, the PS context is sent to MME, guarantee the correct execution of switching.
The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being done within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.