Technical analysis of 3G packet domain

China's 3G network will be operated by a number of operators, in order to allow users to enjoy these services across the operator, the need to achieve different 3G system packet domain interconnection.

Interconnection and interoperability of WCDMA grouping domain and external packet network

Interconnection of WCDMA and Internet

WCDMA is connected to the Internet through the GGSN node of the core network grouping domain, and all the packets accessing the Internet network are routed to the Internet by the GGSN nearest to each operator, and then to the Internet network of the whole world. This does not need to be interconnected with individual internet operators alone. For WAP packets, it is necessary to translate HTTP and WAP protocols through WAP gateways and then forward them to the Internet.

Interconnection and interoperability of WCDMA and private networks

The way in which private and GGSN are interconnected, including the interconnection of tunnels through public networks and the setting up of ISDN, DDN, ADSL or Ethernet lines. The actual application of the way to connect depending on the needs of customers. Because the user of the private net mostly concentrates in the province, therefore proposes the provincial GGSN and the private network direct interconnection, may reduce the route circuitous. For VPN services already on the Web, you can continue to use the original authentication and address allocation method, RADIUS server and DHCP server placed on the enterprise side, the corresponding GGSN need to support the DHCP relay and Radius client features For private networks that do not wish to purchase authentication and address allocation devices, the GGSN side equipment of the operator can be rented and managed remotely. (Computer science)

Interconnection and interoperability between WCDMA group domains

In order to support WCDMA group domain roaming, it is necessary to interconnect the network of WCDMA networks. The different ways of roaming determine the difference of the interconnection point. There are two ways to cross network roaming in WCDMA group domain: Core network packet domain roaming and IMS domain roaming. Which roaming method is used is related to the access point (APN) that the user is using.

Roaming of core network grouping domain

When the user uses the APN of the place to access WCDMA, the SGSN of the visit place routes the user packet back to the GGSN of the territory and then accesses the external packet domain network. The interconnection point of this roaming way is SGSN and GGSN.

This approach increases the routing of packets, increases the load on the network and is not conducive to the real-time business with high QoS requirements. A compromise solution is for roaming users to set up APN configured as APN to visit the site, which can reduce routing detours. But for ordinary users, changing the phone configuration is not easy. Because the billing bill is provided by the operator of the visit, the operator of the place does not have the corresponding statement, so it is unfair to the operator. Because the business level does not know the user's roaming information, so the attribution operator can only collect data bearer roaming fee, unable to collect business roaming fee And because the host network cannot control the QoS allocation of the access network, so this solution is not ideal.

Roaming in IMS Domain

In order to solve the problems caused by the roaming in the group domain, the IMS domain is introduced in the WCDMA R5 phase, and all operators supporting the IMS architecture use the APN to support the unified, when using this APN to access the WCDMA network of the visit area, The SGSN and GGSN of the visiting place route packets from the packet domain to the IMS domain of the visiting site P-CSCF,P-CSCF the session signaling package to the IMS domain of the territory according to the user's domain name. After the session has been successfully established, packets are routed directly to the Internet or to the ggsn/pdsn of other wcdma/cdma2000 networks via the GGSN of the visit, without increasing the routing of QoS-sensitive packets. In this way, users do not need to change any configuration to use the grouped domain business of the attribution network. Because the ownership network and the visit network generate the conversation list at the same time, the business roaming can be billed and the billing is relatively fair. Because the IMS network of the place of ownership can inform the IMS network of the call to visit, the IMS Network can control the QoS allocation of the access network, so the QoS of the service can be ensured when roaming across the network.

How grouping fields are interconnected

There are two ways to interconnect a group of domains, one for one-to-one interconnection and the other for interconnection through a network of interchanges.

One-to-one interconnection means that each operator needs to sign reciprocal interconnection agreements with multiple operators and configure each other's network information with multiple carriers. This way is the traditional PSTN network interconnection, the disadvantage is that the need to sign multiple interconnection protocols, Border Gateway (BG) need to configure too much information.

The interconnection of the transfer network can solve the above problems. The operator only needs to sign the interconnection agreement with the forwarding network operator, and then the network interconnection of the operators will be connected by the forwarding network operator. Transfer network operators do not do specific business, only responsible for network sinks. So the operator only need to sign an interconnection protocol, the boundary gateway only needs to configure the information of the transfer network, which greatly reduces the complexity of interconnection. For example, under the IETF Management GPRS Roaming Exchange Network (GRX) is this kind of transfer network. GPRS operator's core network packet domain GGSN and SGSN's GP interface need to be connected through BG and GRX Network, the network situation is configured to GRX network, for example, GRX's DNS configures the operator's APN configuration information. BG and GRX Networks secure the network by configuring VPNs.

Interconnection and interoperability of WCDMA grouped Domain Services

3G Packet domain service is an important feature of 3G, some of which do not need to communicate with other operators, and some businesses need to carry out business layer interconnection for specific packet Domain Services. There are generally two types of packet domain business interconnection schemes:

When interconnected operators implement business based on the same standard protocol, such as POC business based on OMA, business interconnection can be realized by means of direct interconnection of business centers. This interconnection scheme is simple and does not require additional equipment. But for the packet domain service, the operator usually transforms the standard protocol to provide the differentiated service, and the implementation mechanism and standard are different, so the service center needs to increase the service gateway to convert the protocol.