 Agent Figure 8.10 EV-DO network architecture cdma2000 1xRTT (Radio Transmission Technology) core network architecture. The functions of MSC, HLR, and VLR are quite similar as described in the previous section. There are as such no SGSN and GGSN components in 3GPP2 but similar functionalities do exist in 3GPP2 networks [2, 16]. The most important network element required for packet data services in CDMA2000 (including EV- DO) networks is PDSN (Packet Data Serving Node). The other components are AAA (Authentication, Authorization and Accounting) server, Home Agent and Foreign Agent. EV-DO (Evolution Data Opti- mized) network architecture is very similar to the cdma2000 network architecture. The major difference is that EV-DO (Figure 8.10) does not have MSCs since it does not support traditional voice service: PDSN: Packet Data Serving Node supports packet data services and performs following key functions during the course of a packet data session: Establishes, maintains and terminates PPP (Point to Point Protocol)4 sessions with the subscriber. Supports both simple and mobile IP packet services. Establishes, maintains and terminates the logical links to RAN across R-P interface. Establishes links with AAA requested by devices and provide required parameters for the devices from AAA. Routes packet to and from the external packet data networks. AAA: The AAA server handles subscribers' requests for access to the mobile network. It communicates with the PDSN via IP and performs authentication associated with PPP and Mobile IP connections. Home Agent: The Home Agent (HA) is compliant with IS-8355 standard, required for Mobile IP and needed in every EV-DO/UMB network. One of its main tasks involves the PPP is a data link protocol used to establish a direct connection between two networking nodes. It can provide connection authentication and transmission encryption privacy, and compression. 5 IS-835 specifications provides the basis for supporting packet data roaming between cdma2000 networks. Next Generation Mobile Com