  In this paper, we study the state-dependent two-user interference channel,
where the state information is non-causally known at both transmitters but
unknown to either of the receivers. We first propose two coding schemes for the
discrete memoryless case: simultaneous encoding for the sub-messages in the
first one and superposition encoding in the second one, both with rate
splitting and Gel'fand-Pinsker coding. The corresponding achievable rate
regions are established. Moreover, for the Gaussian case, we focus on the
simultaneous encoding scheme and propose an \emph{active interference
cancellation} mechanism, which is a generalized dirty-paper coding technique,
to partially eliminate the state effect at the receivers. The corresponding
achievable rate region is then derived. We also propose several heuristic
schemes for some special cases: the strong interference case, the mixed
interference case, and the weak interference case. For the strong and mixed
interference case, numerical results are provided to show that active
interference cancellation significantly enlarges the achievable rate region.
For the weak interference case, flexible power splitting instead of active
interference cancellation improves the performance significantly.
