  This paper investigates the downlink channels in multi-cell multi-user
interfering networks. The goal is to propose close-form designs to obtain
degrees of freedom (DoF) in high SNR region for the network composed of base
stations (BS) as transmitters and mobile stations (MS) as receivers. Consider
the realistic system, both BS and MS have finite antennas, so that the design
of interference alignment is highly constrained by the feasibility conditions.
The focus of design is to explore potential opportunities of alignment in the
subspace both from the BS transmit side and from the MS receive side. The new
IA schemes for cellular downlink channels are in the form of causal dynamic
processes in contrary to conventional static IA schemes. For different
implementations, system conditions are compared from all aspects, which include
antenna usage, CSI overhead and computational complexity. This research scope
covers a wide range of typical multi-cell multi-user network models. The first
one is a $K$-cell fully connected cellular network; the second one is a Wyner
cyclic cellular network with two adjacent interfering links; the third one is a
Wyner cyclic cellular network with single adjacent interfering link considering
cell-edge and cell-interior users respectively.
