Interference alignment based dynamic TDD for small cells

Dynamic time-division-duplexing (TDD) uplink (UL) and downlink (DL) reconfiguration is a promising solution to the problem of traffic adaptation in future small cell deployment, wherein the traffic demand may vary dynamically in volume and in transmission direction. Applying dynamic TDD UL-DL reconfiguration in a multi-cell scenario may lead to new challenges caused by inter-cell interference. In this paper, we propose an interference alignment based multiple-input-multiple-output (MIMO) transmission scheme that effectively addresses the interference problem in dynamic TDD systems and improves the system capacity. The proposed scheme may be relevant to 3GPP LTE standardization of enhanced interference mitigation and traffic adaptation (eIMTA), small cell enhancement and coordinated multi-point (CoMP) topics.