An Efficient Signaling Method over Mimo Broadcast Systems with Multiple Receive Antennas

A simple signaling method for multi-antenna broadcast channels is proposed. This method converts the interference matrix – but not necessarily the channel matrix – to a lowertriangular form. Dirty paper coding is used to cancel the remaining interference. The proposed scheme offers several desirable features in terms of: (i) accommodating users with different number of receive antennas, (ii) providing fairness and quality-of-service (QoS), (iii) requiring low feedback rate. The simulation results indicate that the achieved sum-rate is close to the sum-capacity of the underlying broadcast channel. An asymptotic analysis shows that the diversity order of the jth data stream, 1 ≤ j ≤ M is equal to NK(M − j + 1), where M , N , and K indicate the number of transmit antennas, the number of receive antennas, and the number of users, respectively. Furthermore, it is shown that the throughput of this scheme scales as M log log(K) and asymptotically (K −→∞) tends to the sum-capacity of the MIMO broadcast channel.