Space-time coding with transmit antennas for multiple access regardless of frequency-selective multipath

In this paper we design space-time multiuser transceivers suitable for coping with frequency-selective multipath channels (downlink or uplink). Relying on symbol blocking, space-time codes are derived in the frequency-domain and MUI is eliminated without destroying the orthogonality of space-time block codes. The system is shown capable of providing transmit diversity while guaranteeing symbol recovery in multiuser environments regardless of the unknown multipath. In addition to decoding simplicity, analytic evaluation and corroborating simulations reveal the flexibility and performance merits of our designs.