ZTE´s Solution to Convergence of WLAN and CDMA2000 1x

Based on the present situation and future development of telecom networks, ZTE has made solution for convergence of WLAN and CDMA2000 1x.

The WLAN and CDMA2000 1x networks mutually complement each other. Characterized by low cost and flexible networking, the WLAN supports high-rate access of wireless data and open frequency bands. It is applicable in busy places such as airports, hotels and so on, but unable to provide the access service, authentication and accounting function for terminals, nor access service and management for subscribers. The CDMA network features wide coverage, and a perfect authentication and accounting mechanism. However, it has difficulty in providing high-speed access service for end users due to the bandwidth limitation. Hence the convergence of WLAN and CDMA2000 1x can leverage these characteristics to deliver high quality data services for subscribers, thus helping operators attract more high-end users.

1 Network Architecture

According to ZTE´s solution to the convergence of WLAN and CDMA2000 1x, equipment under Layer 3 of the WLAN is responsible for providing a bearer for the link layer in small wireless areas, as defined in IEEE. It can offer subscribers convenient, flexible and high-bandwidth access services. The solution delivers the same authentication and accounting function for the WLAN users as adopted in CDMA2000 1x, therefore it provides subscribers with various and flexible access services. The architecture of converged networks is shown in Figure 1.

2 Functional Entities

(1)Wireless Terminal

When serving as a CDMA2000 1x terminal, it employs standard PPP dialing for access to the general data service node (GDSN). When used as a WLAN terminal, it adopts the standard Point-to-Point Protocol over Ethernet (PPPoE) dialing for access to GDSN.

(2)Access Point (AP)

Made up of the wireless processing module and Ethernet interface module, the AP is responsible for simple wireless user management and dynamic allocation of wireless channels as well as conversion between 802.1b and 802.3 protocols. Usually the transmission distance between the WLAN card and the AP is 30-50 m, therefore the APs should be located at intervals of 30-50 m. The AP proposed in this convergence solution should have all packet messages from the wireless terminals separated at Layer 2 and forwarded to the access point gateway (APGW) so as to achieve control over the wireless terminal.

(3) Access Point Gateway (APGW)

APGW performs tunnel encapsulation for media streams of wireless terminals, which can go through the IP network for access to the GDSN. The APGW, similar to the packet control function (PCF) Module in the 1x network, collects billing information at the wireless side (WLAN) and sends it to the GDSN via the interface between the APGW and the GDSN. Finally the GDSN collects all the information and sends it to the authentication, authorization and accounting server for processing.

(4)GDSN

In addition to the PDSN function, GDSN can provide the packet data access service for the WLAN subscribers. Hence it acts as an access server in both the WLAN and the CDMA network.

(5)Home Agent (HA)

For mobile IP access, HA maintains the binding relationship between the mobile station´s IP address and the transfer address (PDSN´s IP address). It is responsible for forwarding the data packet with mobile station´s IP address as its destination address to the PDSN´s IP address via the tunnel.

(6)AAA

AAA servers, consisting of a visited AAA server, a broker AAA server and a home AAA server, perform authentication, authorization and accounting for both the WLAN and the CDMA2000 1x subscribers.

3 Advantages of the Network Convergence

The WLAN and CDMA2000 1x convergence solution enables CDMA mobile subscribers to enjoy Web service anywhere and anytime, and helps operators build quality networks. By providing differentiated and customized services the operators will be ahead of the competition and win more market share.

(1)Seamless handoff between 1x and WLAN networks

This meets the requirements of on- premise data communication, reduces the impact of large amount of data applications to the 1x network and realizes seamless handoff between 1x and WLAN networks.

(2)Unified billing

This provides accounting settlement on one CDR or one payment card, and supports real-time prepaid service. PDSN and AAA equipment in the existing 1x system are employed to perform the authentication and accounting functions. Combination of these two access modes make possible a unified authentication and accounting for both the WLAN and the 1x subscribers.

It can provide flexible billing modes such as single account and multi-accounts. Flow-based accounting or leased net card service are also available for the WLAN or 1x subscribers. It delivers prepaid service as well as post-paid service to the WLAN subscribers by using the intelligent network of the 1x system.

(3)Provision of new services at high rates

WLAN and 1x subscribers can have a unified access to GDSN, which supports both the PDSN function provided by the CDMA2000 1x access server and the NAS function provided by the WLAN access server. This means that the convergence of WLAN and CDMA2000 1x is an ideal solution for the deployment of high rate MMS and MME services, thus helping operators attract more subscribers (Data rate of WLAN defined in IEEE802.11b is up to 11 Mb/s, and in IEEE802.11a 54 Mb/s).

(4)Unified management and unified service provisioning

Unified identification adopted for the 1x and the WLAN subscribers enables unified user management. What is needed in routine operation is unified core network equipment together with the same O&M interface and the same group of O&M personnel, and this turns out to be a great cost saving.

(5) Independent network evolution and easy capacity expansion

The WLAN offers flexible networking for easy capacity expansion. The two access modes are converged at the GDSN, and they allow independent evolution, i.e. the WLAN evolves on the basis of its own technical development and the 1x follows the development trend specified in 3GPP2.

(6) Smooth transition to 3G

The converged network of WLAN and CDMA2000 1x presents a tremendous advantage and drives down costs. It makes full use of the existing network facilities, which are basically enough for operators to take the responsibility of fostering early 3G users. Therefore the converged network lays a foundation for future technical development and transition to 3G.

(7)Unified authentication and accounting

It is not possible to adopt a unique authentication mode to meet the requirements of all subscribers because the WLAN subscribers are different from the 1x subscribers. The following authentication modes could be available for users.

For CDMA2000 1x users or dual-mode users:

• User name + password mode
• Card ID + password mode
• Handset number + password mode
• IMSI

For WLAN users:

• User name + password mode
• Card ID + password mode

By using the proposed authentication mode, it is easy to realize a unified authentication.

4 Services to Be Deployed

With the high bandwidth offered by the WLAN, the converged WLAN and CDMA2000 1x can deliver a wide range of services including:

• On-line games
• VOD, AOD (Audio on Demand)
• High rate Web browse, FTP, Telnet, E-mail
• Videoconferencing, VoIP
• MOA (Mobile Office Automatization) , E-business

As the WLAN and the 1x are integrated at the GDSN, services deployed in the 1x network are also available in the converged WLAN and 1x network, such as Location position service, MME, WAP, Low rate data services.

5 Application Case of CDMA2000 1x+WLAN

ZTE´s solution for the convergence of WLAN and CDMA2000 1x was put into practice in Shanghai by Shanghai Unicom in early 2003. The functions and operational services provided by the converged network satisfied the operator, which shows the convergence of WLAN and CDMA2000 1x is feasible both technically and operationally. It also proves that ZTE´s solution is feasible and practical both at the technology and product levels.