.a3/a7 Interface Converter Module Atm Interface And Realization

This dissertation is devoted to the researches of some key issues rising from the mutual communication between the IP-based and the ATM-based systems from the point of view of implementation according to "IP-based cdma2000 1x system" known as the key science and technology national launched 863 project- CMT, including the implementation of the ATM interface.There're different characteristics of the CMT system based on IP and other cdma2000 systems based on ATM, therefore, the protocol stacks between the two kinds of network frameworks in the A3/A7 interface are different. In order to accomplish the protocol translation and the message processing, a A3/A7 translation module is needed in the IP-based CMT. After the detailed analysis of ATM protocol and its deployment in the cdma2000 telecommunication system, the design and the implementation of ATM driver for the board iph4532 is described. Some optimized mechanism for the link layer is also proposed. Key points are as follows: To meet the connection-oriented feature of ATM and the different quality of service of signaling and service from upper layer, corresponding schemes are proposed.As the CPU on the board iph4532 is MPC8260, the driver should implement the ATM device driver for MPC8260 FCC , as well as the ATM protocol for the OS VxWorks . A static address mapping scheme is used to fulfill the address mapping of the ATM and the IP for this dedicated system, therefore implements the protocol "IP over ATM" . Moreover, the driver is designed follow the VxWorks END module to ensure the signaling transmit. The same mapping mechanism is applied to AAL2 which has direct interface with the upper layer using the CID. Furthermore, the particular features of MPC8260 FCC ATM controller are discussed and the key implemental methods of MPC8260 FCC s ATM driver are presented in detail. A mechanism of bandwidth utilization is put forward according to the speech coding in cdma2000One of the contribution for ATM forum found that packing density, which is directly linked to link efficiency, depends on the assemble timer Time_CU value of voice trunking using AAL2.Assuming EVRC is used for speech encoding, we set up a Markov chain module to analyze the AAL2 packing process, and then give analgorithm to calculate a reference Timer_CU value to achieve desired link efficiency. The simulation results verify the theoretical conclusion. To bring forward and implement the mechanism of priority for receiving and transmittingTo satisfy the graded quality of service for the signaling and the service on the A3/A7 interface, two level ATM cell scheduling mechanism including service level and channel level is proposed for transmitting and higher VxWorks task priority is assigned to AAL2 for receiving.