Institute of Electrical & Electronic Engineers
Joint Transmission (JT) allows multiple Base Stations (BSs) to serve multiple UsErs (UEs) in the same time and frequency resources, which will causes Inter-User Interference (IUI). Moreover, different signals from different BSs can't be executed coherent combination directly in non-coherent JT. In this paper, a Two-Step Pre-coding Scheme (TSPS) is proposed to solve these problems. Firstly, an alternating minimization algorithm over the pre-coders at BSs and the interference subspace matrixes at UEs based on Interference Alignment (IA) is applied, which can force interference at each UE into the subspace and make each UE observe the interference-free desired signals. Secondly, the authors use the PHase Adjustment (PHA) based on QR decomposition to implement the coherent combination of desired signals from different BSs.