Construction of Group network and service platform of 3G core network in packet domain

Introduction

The author was fortunate to participate in the overall project design of the third generation mobile communication technology test network of the Ministry of Information Industry and the design work of the Beijing Area Test Network project. 3G test Network adopts WCDMA R99, CDMA2000 1X, TD-SCDMA three kinds of technology construction. When considering the 3g scheme, we combine the characteristics of 3G network, based on satisfying the requirements of the test, and draw on the experience of 2g/2.5g commercial network. Based on the third generation mobile communication technology test network of the Ministry of Information industry, this paper discusses how to build a commercial network, aiming at the construction of the packet domain and the service platform, and using some experience from the experiment network.

1, the network organization of the grouping domain

WCDMA R99 core network packet domain architecture is the same as GPRS, using packet switching technology and control plane using SS7. The packet domain network element includes: SGSN, GGSN, simultaneously with the circuit domain sharing HLR. The interface of the grouping domain includes the GN and GI,SGSN Connection wireless subsystem and the core network grouping domain, the GGSN is connected with the external network through the GI interface.

CDMA2000 1x core network grouping domain and circuit domain have obvious boundary, packet data service is completely based on IP technology, packet domain interface is simple. The packet domain network element includes: PCF, PDSN, RADIUS (if the mobile IP is used, also need ha and FA). PCF is usually a physical entity with the BSC, used to forward messages between the wireless subsystem and the PDSN, PDSN for the connection between the group domain and the external network.

The TD-SCDMA core network grouping domain is the same as WCDMA R99, and is considered in the following. (Computer science)

1.1 Network Element Setup

In the test network, each system is relatively complete in order to facilitate individual testing of each manufacturer's system. Each set of WCDMA systems contains SGSN and GGSN, and each set of CDMA2000 systems contains grouped domain devices such as PDSN. The test network constructs a public DNS in each city, is responsible for the domain name resolution in the City Group network.

But in the actual network, we need to consider the setting of the network element according to the traffic volume. The following is based on WCDMA and cdma2000 two kinds of technology to consider respectively.

(1) Wcdma

Mainly refers to the setting of GGSN, SGSN, GGSN and SGSN can be set in the same place, can also be set up separately, generally according to the provincial considerations. According to the size of the network is divided into two ways or two stages.

Mode one: The GGSN is set at the provincial level and set up in pairs, each is backed up. SGSN is set at the local level, and a small number of smaller local networks can share a SNSN. Mode two: GGSN and SGSN are all set at the local level. Multiple business-smaller local networks can share a single GGSN;SGSN can be set up in each local network, where a large volume of the local network can also set up multiple SGSN.

(2) cdma2000

Mainly refers to PDSN/FA, AAA server, HA local agent, such as grouping domain device settings. According to provincial considerations, AAA and HA can be set centrally in the province, Pdsn according to the size of the network divided into the use of centralized, distributed two sets of methods.

Centralized: The whole province uses a set of grouping domain equipment, centrally set in the provincial capital city.

Distributed: The province is divided into several regions by business volume, geographical location and correlation degree, and the grouping domain device is set up in each region. The area can be more than one local network, or it can be a local network.

WCDMA and CDMA2000 Although the packet domain network element is different, but the two ways or two phases of the network element setting are similar. The initial size of the small timely use of the first set up a way to compare the economy, easy to centralized management and maintenance. With the increase of business volume and the expansion of network scale, we should transition to the second way, the second way can be flexible business expansion and introduction, security is better.

For domain name server DNS, different 3G technologies can be shared. Its settings are also divided into two categories: set at the national DNS level, and by national root DNS and provincial level DNS two. For security reasons, DNS Cheng settings. To simplify the network structure and facilitate management operations, DNS is best set up in the core node.

Construction of 1.2 bearing network

3G Service Network is based on the load network, from the network element settings can be seen: WCDMA hosting network mainly provides core network packet domain SGSN and GGSN and SGSN and SNSN of the GN Interface Connection and GGSN of the GI interface and the external data network connection. GN interface based on IP, using GTP protocol, GI interface using IP protocol. According to the CDMA2000 1X network mode, the bearer network mainly provides the core network grouping domain PDSN and the external packet data network and the wireless network and the PDSN connection, two kinds of connections all adopt the IP network.

As the test network is independent of the current network, do not need to separate the different operators, different technologies to isolate, using IP over SDH way to build IP network as a packet-domain hosting network, and three kinds of technical network of the grouping domain shared a unified IP platform. The load-carrying network adopts two-level network structure, which consists of IP national backbone network and each city IP local network. Because SGSN and GGSN, bsc/pcf, and Pdsn are located on the same node, connectivity is achieved through an internal LAN. For WCDMA and CDMA2000 packet domain and external packet data network connection, hosted in IP private network.

In the actual network, from the development direction of all IP network, 3G packet-domain bearer network should be based on IP network. When adopting a network of 3G technology, it is suggested that the operators adopt a unified IP hosting platform, which is helpful to realize resource sharing and save investment. The construction of 3G load-carrying network can be implemented in two ways:

-use of existing networks;

--The establishment of IP private network.

The operators can combine their own situation to consider comprehensively.

(1) Using the existing IP network of operators

In order to save investment, the existing data network resources can be considered when the initial scale of the construction network is small. In order to ensure the security of 3G packet domain network and to carry the real-time service, the virtual private network technology should be used to isolate the 3G data service and other services.

①WCDMA GN Interface Bearer Network implementation: The use of existing IP network, using IP VPN or VLAN mode.

②wcdma GI interface and external Data network connection: You can use the existing IP network, through the GI interface to the IP network of routers, using IP VPN method. can also use the existing ATM network: Through the GI interface to the ATM network, using IP over ATM mode.

③cdma2000 1x PDSN with the external packet Data Network connection: the implementation of the use of IP VPN.

④ Firewall settings

When using an existing data network as a hosting network for a 3G grouping domain, a firewall is set between the 3G packet-domain device and the external network in order to ensure the security of the network. For WCDMA, firewalls should be set up between SGSN and GGSN in different locations and between GGSN and external networks. For CDMA2000, the security firewall should be located between the PDSN and the external data network and PDSN and wireless networks in different locations. In addition, some important servers in the network, such as DHCP, DNS, billing server and Business Server and other devices need to place firewalls and external network isolation.

(2) New Independent IP network

Although the data network resources, but for network security, ease of management, and capacity of the comprehensive consideration, in the introduction of 3G network, operators can also create new IP private network as a 3G packet domain hosting network.

The network structure of IP private network: From the use of transmission resources, convenient management and maintenance considerations, it is appropriate to adopt a layered structure. The structure of the new bearer network should be adapted to the network element setting of the group domain. IP network can be divided into core layer, aggregation layer and access layer three layer structure or backbone layer and access Layer two layer structure, wherein backbone layer contains core layer and convergence layer routing function. The network structure is adopted between the core layer nodes and the converging nodes in the same region, the double star structure is partitioned between the core layer and the Convergence Layer node, and the double star connection is used in the node partition of the convergence layer and the access layer.

IP private network to achieve the way: You can use IP over the WDM,IP over SDH technology, IP over ATM and other means. The choice of specific ways to consider the business type, bandwidth, to the future evolution of the network and other factors.

2, the construction of business platform

2.1 Service platform sharing in different 3G technologies

In this 3G test network, WCDMA system is set up WAP gateway, LCS location Service platform, MMS, Java platform, SMS Center and gateway, streaming media server; cdma2000 system has set up positioning platform, Java platform, multimedia mail platform, streaming media platform, WAP platform, Videophone platform, Brew Platform and SMS Center and gateway. TD-SCDMA In addition to positioning platform, the common use of WCDMA business platform.

From a technical point of view, most business platforms for different 3G technologies can be shared, as follows:

(1) The SMS system is connected with 3G network through signaling network. In WCDMA, the SMS system can be connected with the core network MSC, or it can be connected with SGSN through GD interface. In CDMA2000, the SMS system is only connected with the core network MSC. Because of the different signaling protocols supported by WCDMA and CDMA2000, two kinds of technologies should be set up separately, and TD-SCDMA can be shared with WCDMA.

(2) The location of the business can be through the signaling network can also be connected through the IP network 3G network. Because WCDMA and CDMA2000 network support the different protocols, and WCDMA, TD-SCDMA and CDMA2000 in the wireless location of the implementation of various ways, three kinds of technology should be set up separately.

(3) WAP, Java, MMS, streaming media is equivalent to the business of IP network, they are supported by different technologies of the IP protocol is universal, as long as the host on the same IP platform, three kinds of technology can realize business platform sharing.

Therefore, the future operators in the adoption of more than one 3G technology network, you can consider the business platform in accordance with the common use.

2.2 Setup of Business platform

In this experiment, from the test convenient, simple and easy to operate, in Beijing, Shanghai, Guangzhou, respectively, set up a business platform, which Beijing set up all the business platform to test, Shanghai and Guangzhou set up some business platform. In the commercial network, the operator needs to consider the setting of the business platform according to the scale of the network and the development of the business. For easy operation, maintenance and unified management, for the current business volume is not too large business platform using the whole network set the way, at the same time in the same city all kinds of business platform is best centralized placement; When the volume of business is large, in order to facilitate the local characteristics of a flexible business development, improve security, it is recommended to set up a provincial or The best service platform is the same address as the core node, which can simplify the network structure and facilitate the unified maintenance and management.

2.3 Connection of service platform and 3G network

The service platform is connected with the 3G core network through signaling network or IP network.

In the test network, the short Message center and the positioning platform are connected with the 3G core network through the signaling network. In the signaling network, they set up the quasi-direct signaling link as SP only with the stp/sp of the city, and the other SP points are transferred through STP. In the commercial network, when the amount of information is small, the short message center and positioning platform can be connected in a similar way; When the information is large, the short message center and the positioning platform as SP besides and STP set up a quasi-direct signaling link, but also directly with the local MSC and HLR set up direct signaling link.

Each business platform can connect with the 3G core network through the external IP network. In the test network, in addition to the short message center and positioning platform, other business platforms are connected in this way.

3. Concluding remarks

The above is we participate in the 3G Test network engineering design of some of the harvest and experience, share with you, hope that the future of the 3G Commercial network construction for reference. With the continuous maturity of 3G network, there will be new problems, bring new thinking, and hope to continue to explore together with you.