TABLE OF CONTENTS The EVDO system was designed using a layered processing approach where each layer performs specific control functions and uses one or more protocols. The use of layers allows for the addition of functions and modification of protocols without requiring significant changes to the system. The EVDO system has 7 layers: application layer, stream layer, session layer, connection layer, security layer, MAC layer, and physical layer.
The application layer coordinates the information interface between the communication device and the end user. The application layer receives data from the underlying protocols and processes this information inta form required or requested by the user or endpoint device. The application layer usually requests or responds to requests for a communication session. The location of the application layer is at the top of protocol stacks.
The application layer uses several protocols to coordinate the overall flow of information between user applications. These include signaling network protocol (SNP), signaling link protocol (SLP), radio link protocol (RLP), and location update protocol (LUP).
Signaling network protocol (SNP) coordinates the overall transfer of signaling control messages that are initiated and received from other protocols. Signaling link protocol (SLP) manages the transfer (transport) of specific SNP messages over a specific link. SLP is responsible for dividing (fragmenting) large messages, confirming message receipt for reliably delivery services, and efficiently transferring unconfirmed or broadcast messages for best effort delivery services. Radio link protocol (RLP) coordinates the overall flow of data packets across the radio link. RLP uses error detection and...
