On the Achievability of Interference Alignment for Three-Cell Constant   Cellular Interfering Networks
  For a three-cell constant cellular interfering network, a new property of alignment is identified, i.e., interference alignment (IA) solution obtained in an user-cooperation scenario can also be applied in a non-cooperation environment. By using this property, an algorithm is proposed by jointly designing transmit and receive beamforming matrices. Analysis and numerical results show that more degree of freedom (DoF) can be achieved compared with conventional schemes in most cases. 
Yanjun Ma, Jiandong Li, Rui Chen, and Qin Liu
cs.IT math.IT