Loose or compact? Comparison of 3G + WLAN networking at Home and Abroad

With the advent of the 3G communication era, it has also brought a variety of multimedia applications. In recent years, the rapid development of high-speed WLAN, which can provide close data rates, has gradually become an important application for the combination of 3G and WLAN, and has a deep potential for market development. In the 3GPP and other mobile communication standardization organizations, the convergence of 3G networks and WLAN has also been concerned, and discussions and standards have been completed, it is also supported by many international equipment providers and telecom operators. The ban on built-in WLAN modules (WAPI) of mobile phones in China is gradually being lifted. Many mobile phone manufacturers have begun to launch mobile phones with WLAN functions in the Chinese market, this provides a broad domestic user space for 3G + WLAN hybrid networking.

The development of mobile communication systems has ushered in the 3G era. A network convergence environment with "Ubiquitous bandwidth" is being formed. However, due to the immature 3G high-speed broadband technology, telecom operators are turning to the integration and development of 3G and WLAN technologies. The features of WLAN make up for the Business gap when 2G is heading for 3G. carriers can use WLAN to quickly and cost-effectively carry out mobile high-speed data services and seize high-end users.

Foreign cases: "loose" integration mode

A 3G + WLAN system of a foreign operator implements a hybrid networking of the CDMA 20001x network and the WLAN. The terminal is a dual-mode mobile phone that supports the 1x interface and WLAN interface.

In this system, the terminal can access three wireless networks: 1x network, public WLAN Network, and Enterprise Internal WLAN Network. From the core network, we can see that the internal network of the enterprise is connected to the programmable User Switch (PBX) through the voice call continuity Application Server (VCC-AS), and the PBX is connected to the PSTN through the DS-3 link, in this way, the IP voice data generated by the enterprise intranet is processed by the VCC-AS, it will become the acceptable voice signal of the PSTN to be transmitted in the backbone network. The VCC-AS function is to provide two-way switching between IMS domains (such as Wi-Fi access) and 2G/second CS domains at the business layer to ensure business continuity.

This system enables users to implement voice call services through the public WLAN Network and the enterprise's internal WLAN Network in the core network of CDMA 20001x. Specifically, you can use the WLAN interface on the terminal to connect to the Internet through the WLAN Network for voice calls to users in the CDMA 20001x network or other public telephone exchange network.

The system actually implements a loose convergence between 3G networks and WLAN. The operations between 3G networks and WLAN networks are independent of each other, identity Authentication for users is actually performed by devices in the enterprise intranet. From the perspective of 3G core network, all the enterprise intranets connected with the VCC-AS can be seen as a user, the 3G/WLAN dual-mode terminal is actually an extension of the enterprise's internal network to the external Internet or internal WLAN.

Advantage: the advantage of this networking mode is that the implementation method is simple, operators only need to install VCC-AS in the internal network of enterprise users, will not generate redundant signaling load in the existing 3G wireless network, in addition, the existing WLAN devices do not need to be modified. In the authentication and billing, the operator only needs to certification and billing of the business generated by the VCC-AS, without the need for a dedicated authentication billing for each multi-mode terminal.

Disadvantage: however, this networking method also has a prominent defect, that is, when a user uses a public WLAN for voice calls, the service quality cannot be reliably guaranteed, if the data traffic is large or the load is high, a large amount of user IP voice packets may be lost, resulting in a serious reduction in the quality of voice services.

Domestic Case: both "Compact" and "loose"

In a 3G + WLAN hybrid networking solution of a carrier in China, including BTS, BSC/PCF, GDSN/FA, AAA and other network elements. HA is an existing device in the CDMA 20001x network structure, and AP is a wireless LAN device that complies with the 802.11 standard.

A wireless terminal can be a mobile phone or PDA with both WLAN and CDMA 20001x interfaces, or a portable computer with only a WLAN Nic, 1x Nic, or dual-mode Nic, or other wireless terminals with WLAN Access functions. When the terminal accesses the network through the CDMA 20001x interface, it uses standard PPP dial-up to GDSN. When it is used as a WLAN terminal access, PPPoE is used to dial up to GDSN.

In addition to the existing functions of the CDMA 20001x network, GDSN/FA devices also need to manage wireless end users connected to the network through WLAN interfaces, HA and other network entities work together to authenticate and charge users. In addition, the device also needs to forward media streams.

When the terminal is connected through the MobileIP protocol, the HA (hometown proxy) needs to maintain the binding relationship between the mobile IP address and the transfer address (gdsn ip address, it is responsible for forwarding packets whose destination address is the terminal IP address to a device with a forwarding address through a tunnel, that is, GDSN.

The AAA device is responsible for authentication, billing, and proxy forwarding.

AP devices are responsible for connecting Wireless terminals to a fixed telecommunication network, providing users with WLAN Access functions, providing voice and data services, simple management of WLAN users and allocation of WLAN wireless channels, converts 802.11 to 802.3 protocols.

The AP Access Gateway is used to encapsulate the media streams from the WLAN in the third layer to increase transmission flexibility and ensure that the wireless LAN users can access the 3G core network. Specifically, APGW encapsulates the GRE tunnel of the media stream on the WLAN terminal so that the media stream can reach GDSN through the IP network.

This hybrid networking solution supports both the "Compact" mode and the "loose" mode with great flexibility. Regardless of the Mode Supported by the network, this solution provides unified management, authentication, and billing for users, as well as unified management of network devices. Most importantly, the network elements involved in this solution can coexist with existing network elements in the existing network, without affecting each other. When the scheme runs in "Compact" mode, GDSN can simultaneously access two types of users, namely, CDMA 20001x and WLAN. when working in "loose" mode, in this solution, access control can be implemented for users from the CDMA 20001x and WLAN respectively, that is, functions originally completed by GDSN in the "Compact" mode are allocated to different access servers.

Advantage: This CDMA 20001x + WLAN hybrid networking solution has five advantages. First, the system architecture fully complies with the CDMA 2000 standard; second, the terminal can easily achieve cross-network switching; third, low operating costs and easy maintenance; fourth, it facilitates new businesses; fifth, provides WLAN users with service quality assurance.

Disadvantages: On the other hand, a problem with the hybrid connection solution of CDMA 20001x and WLAN is that terminals with WLAN interfaces must access the WLAN Network to receive corresponding services, in this way, compared with the scheme of a foreign operator described above, the flexibility of WLAN service access is subject to the WLAN deployment scale of the operator. If the carrier's WLAN deployment scale is large, you can easily obtain the services provided by the carrier anytime, anywhere through the WLAN Network. Otherwise, in this case, it may be difficult for users to obtain services through the WLAN interface, so that the so-called 3G + WLAN hybrid network is switched back to a single network that is still dominated by 3G independent networking. (Special contributor Yu Yifan Hu Jian Cun)

Link: Six 3G and WLAN fusion scenarios recommended by 3GPP

Public billing and Customer Service

The simplest way to connect. In this way, the user receives a single bill from the mobile operator, including 3G network and WLAN network service charges, but the security mechanisms of the two systems are completely independent.

3GPP-based access and Billing

3G networks and WLAN adopt the same security mechanism. Authentication, authorization, and billing are provided by 3G networks.

Group domain service based on 3GPP

In this scenario, the operator is required to expand the group domain service of 3GPP to WLAN, including IMS-based services, positioning services, and instant messages. However, there is no requirement for business continuity between the 3GPP system and the WLAN.

Business Continuity

When the WLAN and 3GPP access systems change, the group domain service can continue to maintain business continuity.

Seamless business

Seamless business continuity means that when a mobile phone switches between 3G and WLAN wireless access technologies, as little data is lost and as short as possible interruption time.

Access to 3GPP circuit domain business

The mobile phone is connected to the core network circuit switching domain of 3GPP through the WLAN interface, and is transparently exchanged with the user between different access technologies to connect services in the bearer circuit domain.

1. 3G and WLAN will be deeply integrated into the new favorite of Operators
2. The WLAN speed is higher than the initial 3G network enterprise gateway to revitalize carrier Resources