Scattering Division Multiple Access

The paper presents a new way of multiplexing digital communication over cable networks. The system is innovative in three ways. Firstly, the way the multiple access scheme is achieved. Actually, most of current cable multiplexing systems use TDMA. Other well known techniques -especially in wireless domain -use FDMA, CDMA or SDMA. The proposed system uses the scattering properties of the cable network to separate the information streams coming from the different digital sources. We will refer to this technique as Scattering Division Multiple Access (ScDMA). Secondly, although the digital information goes from the transmitter to the receiver, the transmitter does not send any physical signal, but the receiver does. The receiver reads the transmitter\´s information by sending signals and analyzing the scattering parameters. The digital stream is encoded by letting transmitter impedance vary: for instance, "0" might be encoded with a high impedance and "1" with a low impedance. Thirdly, the way the channel is approached is novel. Generally, in communications systems, a random channel is imposed, and the processing aims at canceling its effect in a trained or blind manner. Here, the channel is controlled and the principle is to artificially create a multi-path environment in a deterministic manner. The main advantages of the system are its instantaneous multiplexing ability (simultaneous sources separation and no request latency) and the low complexity of the transmitters. The system has been developed based on PLC channel model, but the principle is general and can be applied to any communication system over cable networks.