Research on the third generation mobile communication system and wireless LAN interconnection

Absrtact: This paper expounds the background of the third generation mobile communication system and wireless LAN interconnection, architecture, key mechanism and application scenarios, especially the key mechanisms such as network selection, authentication, verification, billing, data Routing and so on, the corresponding solutions and the network architecture under two different scenarios are given.

0. Overview

In the IST Project Brain (broadbandradioaccessfor IP based Networks) and mind (Mobile ip-based Network) Provides different solutions for broadband access based on full IP, and one of the major challenges is the interconnection of 3G with wireless local area network (WLAN). WLAN, based on the IEEE802.11 standard, rapidly expands the market space with its low cost of construction and high transmission bandwidth (1-54MBIT/S data transmission rate provided by IEEE 802.11 series standard). But it is also obvious that the coverage of each access point is small, only applicable to companies, hotels, airports and other regions, and there is no roaming protocol between the networks of different WLAN service providers. 3G can make up for the disadvantages of WLAN: It can provide users with ubiquitous connectivity and mature roaming protocols between different PLMN. But the 3G investment scale is huge, the data peak transmission rate also only 2mbit/s about [1].

Due to the complementary characteristics of WLAN and 3G, 3g-wlan interconnection becomes one of the hot issues in equipment manufacturers, system integrators, operators and research institutes. The basic principle is to minimize the impact on WLAN and 3G existing standards and systems, that is, to keep WLAN standards unchanged and to minimize changes to the 3G existing specifications. The aim is to enable 3G system operators to provide a complete set of public wireless LAN access systems for cellular users in all businesses.

1, 3gpp-wlan interconnection system structure

The design of 3gpp-wlan interconnection architecture is mainly based on complementary and enhanced functions of two systems.

1.1WLAN Architecture

The current WLAN access network architecture does not have a formal standard, but all WLAN systems are built on the ISP's actual standard paradigm, as shown in Figure 1 [2].

Figure 1 WLAN Architecture

Provide IP connectivity through WLAN systems and other business needs for certification, authentication and billing (AAA) servers and user databases. The current typical AAA server is a RADIUS server that provides authentication, authorization, and billing capabilities to users in WLAN systems. (Computer science)

1.2WLAN-3GPP Architecture

Currently, there are two modes of WLAN and 3GPP interconnection: tight coupling and loose coupling. WLAN can directly draw on the user management and AAA mechanism of 3G system, which makes it easy for users to access different modes of wireless network seamlessly and quickly. See Figure 2 below.

Figure 2 WLAN-3GPP Architecture

2, 3gpp-wlan interconnection key mechanism

2.1 Network selection mechanism

Network selection in 3gpp-wlan interconnection system is a very complicated problem. Although the traditional mobile operators provide WLAN access network, there may be several feasible roaming paths for a particular WLAN access network. At present, 3GPP supports network selection in WLAN interconnection, and users can choose to access PLMN (VPLMN) when there are multiple feasible roaming paths. Technically based on a network access identifier (NAI), Nai consists of a user name and a domain name separated by the @ character. When a connection is made to a WLAN access point, the UE reports to the local network that NAI, if WLAN Access cannot forward this request to the local network, this WLAN provides a list of supported VPLMN for the UE, from which the UE chooses the preferred VPLMN, The WLAN obtains information about forwarding the request by Vplmnid the NAI and including it, and authenticating it again with a "new" ID.

Authentication and verification in 2.23gpp-wlan interconnection system

The basic principle of 3gpp-wlan interconnection system requires as few new requirements as possible for WLAN access network, so it is proposed to use ieee802.11i to realize authentication, solution control and key recognition function in planning. Ieee802.11i has extended the security performance of the IEEE802.11 protocol. Authentication and key acknowledgement functions can be achieved by a centralized authentication server via RADIUS (Remote authentication dial-in User Service) and Extensible Authentication Protocol EAP (Extensible authentication Protocol) to achieve. To reuse the Usim/sim authentication algorithm, the EAP SIM and EAP AKA (authentication and Key agreement) are regulated.