In addition to testing wireless devices with TAP in a factory/laboratory environment (see C.S0029 Test Application Specification Description (TAP/ETAP) ), the lab application can emulate a real-world access network to provide packet data connection between an access terminal (AT) and a packet data network (such as the Internet). This is achieved by emulating the relevant behaviors of the Access Network (AN) using the Default Packet Application protocol (see Session Application Type ), the Packet Control Function (PCF) as well as the Packet Data Service Node (PDSN) as shown in the figure below.
When a packet data connection is established (that is, both the physical traffic channel and PPP connection are open between the AT and the test set), the AT can send or receive data through the test set's front panel RF connector, and the test set will route data through the rear panel LAN port to or from a packet data network (see How Does Test Set Support Simple IP Packet Data Connection? ).
There are several applications of the Data Channel. See Data Channel Applications .
For the signaling procedures during packet data connection establishment, see Packet Data Connection Call Flow .
For the state transitions during a packet data connection establishment, see Packet Data Connection Processing States Lifecycle .
The figure below shows a simplified protocol reference model for packet data service. The Default Packet Application Description (DPA) protocols are briefly explained here. For other communication protocols, refer to the Standard References .
The Default Packet Application (DPA) is an application layer protocol defined in the 3GPP2 C.S0024 Section 3 . It provides an octet stream used for transporting user data. The applications used and the streams upon which they operate are negotiated as part of session negotiation. The DPA protocol consists of the following protocols: