ZTE mobile softswitch server, ZXUN iCX, is an important control network element (NE) in overall ZTE mobile softswitch solution. Located at core control layer in GSM/UMTS/TD-SCDMA network, it provides calling control, media gateway control, user data management, and inter-network interworking functions. ZXUN iCx's built-in MGCF function can cooperate with other entities in the IMS network (such as CSCF, BGCF) and other entities in CS domain (such as MSC server) to realize the communication between the IMS domain and the CS domain. By controlling the IM-MGW, it can achieve the interoperability between the user plane between IMS domain and CS domain. ZXUN iCX also supports service function of VMSC, TMSC, GMSC, CMN, and SSP in GSM/UMTS/TD-SCDMA network, and realizes networking flexibly. ZXUN iCX could be smoothly evolved to MGCF/mAGCF in IMS network, and protects operators' investment
1． CSFB Function
CS Fallback is a technology that allows UEs in an EPC network to fall back to CS domain and obtain voice continuity with CS network infrastructure. ZXUN iCX supports the CSFB function, which enables LTE users to register in the CS network when voice services are needed, and to return to the LTE network when voice services are not needed, so that the users can enjoy both the stability of voice services in CS network and the high-speed data services in LTE network.
2． SRVCC Function
SRVCC is a single-frequency voice continuity technology that is used to handover the voice calls of IMS user from the LTE network to the CS network, in order to ensure the continuity of voice services. ZXUN iCX can be deployed as visited MSCS to support SRVCC and directly connect to the BSC/RNC. When the SRVCC handover occurs, it switches to the 2/3G network under the control of ZXUN iCX. ZXUN iCX can also be deployed as SRVCC Proxy MSCS and connects with other visited MSCS. When the SRVCC handover occurs, MSCS acts as a proxy node and performs the handover of call to the 2/3G access which is under the control of visited MSCS.
3． ICS Function
ICS refers to the centralized control of services in the IMS. The CS domain only serves as an access channel for the IMS and provides a mechanism for using the CS media bearer for IMS sessions. ZXUN iCX supports the ICS function based on I2 interface. Through the ICS function, all services of mobile users can be provided by IMS. When a user accesses through CS mode, the session initiated by the user is also controlled by IMS.
4． Visited MSC Server (VMSC Server)
As VMSC Server, it provides switching and signaling functions for mobile subscribers in local MSC area, supporting RNC and BSC access at the same time. For subscribers in MSC Server area, it processes circuit-switched incoming/outgoing calls. VLR is embedded in VMSC Server. VLR stores all data necessary for MSC Server to create and release calls and provides roaming and supplementary services. It also tracks the dynamic location changes of mobile subscribers that enters local VMSC Server area and stores all information about them (such as IMSI, MSISDN, MSRN, TMSI and SGSN ID). Here, mobility management, security management and call control functions are carried out
5． Gateway MSC Server (GMSC Server)
As GMSC Server, it is a gateway function node between WCDMA core network circuit domain and external network. It can be connected with PSTN, ISDN or other PLMN, enabling communication service between fixed subscribers and mobile subscribers. GMSC Server can query the location of a mobile subscriber based on the MSISDN number. After getting the MSRN, it connects the call to VMSC Server of the called. When GMSC Server acts as the inter-network mobile gateway, it performs important functions such as route analysis, inter-network access and inter-network settlement.
6． Service Switching Point (SSP)
SSP implements SSF, CCF and built-in SRF functions in CAMEL DFP. It is service control, call control and resource management functional entities. With MSC Server as the platform, SSP performs call flow control based on operation code, resource code and detection point (DP) in SCP message. It also performs resource scheduling and returns the execution result and detected status to the SCP to determine the subsequent service orientation.
7． MGCF Function
ZXUN iCX can be deployed as a MGCF to interwork IMS and CS/PSTN services, acting as a gateway between IMS network and CS/PSTN network. In addition, MGCF also implements signaling conversion between SIP and BICC/ISUP.
1. Carrier-Class NFV, stable and reliable
NFV solutions for control plane and user plane
Component-based open architecture, easy integration, simple O&M
Software/hardware decoupling, saving power consumption and floor space, lower TCO
Carrier level reliability 99.999%
2. Overall network security Guarantee
1) Multi-Dimensional load monitoring: system resources, number of users, traffic, network bandwidth, and so on.
2) Overload control: quick response to burst load spikes, protect NE operation safety
3) Flexible adaptation: automatically scale-in/out based on the load changes
3. Smooth evolution to Cloud, and inherit the exiting service function
1) Fully use the existing equipment to protect investment: cloud CS NEs and the traditional CS NEs has achieved functional alignment, and can achieve hybrid networking with unified EMS management
2) Disaster recovery smooth upgrade: 1+1 main/standby disaster recovery backup methods in traditional CS can be smooth upgraded to N+M disaster recovery backup methods in NFV network without effecting service