ATM switch design using Code Division Multiple Access techniques

In this paper, we present a new architecture for an electronic implementation of an ATM switch using a technique from spread spectrum communications known as Code Division Multiple Access (CDMA). In a CDMA-based ATM switch, each output port is assigned a unique code word from an orthogonal set of code words. Each input data stream is encoded using the code word corresponding to its intended destination output port. Coded data from different input ports are then added together and broadcast to all of the output ports. Each output port is able to select its appropriate data stream using coding theory. In this way, complex internal routing within the switching fabric is avoided. In our basic method, the input data are expanded by a factor equal to the number of bits in a code word. A second, more sophisticated method called exponential extension is also introduced to reduce the data expansion rate so that more efficient hardware implementations can be obtained.