A new practical dirty-paper coding strategy in MIMO system

In this paper, we propose a new broadcast strategy for a MIMO system with N transmit antennas at the transmitter and M < N single antenna receivers. The proposed method spatially separates the M users but does not suffer from the power loss of classical SDMA. For the special case of M = N = 2 and when the two single antenna receivers are assumed to be colocated, the proposed scheme produces a 2 transmit, 2 receiver antenna MIMO scheme. This gives a MIMO transmission scheme that doubles the symbol rate of MIMO STBC systems (Alamouti scheme) from one to two symbol per transmission time. It is proved that it provides the same performance level as that of the Alamouti STBC for the first symbol, and the same performance as the BLAST system for the second symbol. When compared to the BLAST system, our scheme has the same symbol rate, but enjoys significant performance improvements, since it provides 2 level diversity per symbol on the first symbol while the BLAST system does not provide any diversity.