In this paper, we develop linear interference alignment (IA) approach for multi-input-multi-output interference broadcast channel (MIMO-IBC). Since multiple data streams from each base station (BS) to multiple mobile stations (MSs) experience identical channel, it is hard to ensure the rank constraint to the intended MSs in the desired cell meanwhile ensure the interference aligned at the unintended MSs in other cells. Considering the difficulty in aligning interference at the receiver in MIMO-IBC, we design a transceiver to align and eliminate the interference at the transmitter. Specifically, we first design receive vectors of all MSs to align the inter-cell interference at the BS side, and then design the precoder of each BS to eliminate all the intra- and inter-cell interference. The proposed approach can be applied for general MIMO-IBC and has closed-from solutions for some antenna configurations. Simulation results validate our analysis and show that the proposed IA transceiver can achieve the maximal degrees of freedom of MIMO-IBC and attain a good trade-off between the maximal number of data streams and signal-to-noise ration gain.
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