The Structure And Implement Of A High Speed Data Switch Network

The task of this research is to design a high speed data switch network which is used in a base station controller (BSC) of a digital mobile communication system based on CDMA technique. This data switch network should satisfy the system requirement based on IS95A/B and take into account of the smooth system transfer to a CDMA1X system.This data switch network consists of data switch control unit (DSCU), data interface unit (DIU), channel / data service unit (C/DSU). The data switch bus is a dual bus system with 16bits width. Up link direction is from DIU to DSCU, down link direction is reversed. DSCU is the control unit. DIU receives and sends serial data. C/DSU changes the format of serial data and matches the physical data link. DIU receives the serial data and stores the data in the received data buffer. Then the data is send to DSCU in a manner of round-robin. DSCU control the data to down direction bus. DIU judges to receive the data or not by the head part of the data frame. If yes, the data is stored in the send data buffer. The data switch process finish. Then DIU sends out the data. C/DSU has two types of ports. One type, called MSSL, only one port per C/DSU, connects to DIU with no time slot HDLC format. The other, normally several E1 ports, connects to the devices using E1 port.The capacity of data bus is smaller than that of the sum of all serial ports, so the flow control function is introduced. The network is a private network, there is no commercial IC suitable for the system design. Programmable logic devices become the key devices for the system implement. This paper describes the whole structure and the detail design of the system. Especially it introduces the design of DIU board, HDLC serial communication controller and the control software of DIU.