Abstract: A data coding/decoding system for use with a plurality of users includes an encoder, a transmitter, a receiver, and a decoder. The encoder encodes data to be transmitted over a shared physical transmission medium using an orthogonal or convolution code associated with a receiving user. The transmitter transmits the encoded data. Generally, data may be transmitted simultaneously by a plurality of users. The receiver receives a stream of encoded data and forwards it to the decoder, which decodes it based on the orthogonal or convolution code of the receiving user.