  In this paper, we consider the K-user interference channel with partial
cooperation, where a strict subset of the K users cooperate. For the K-user
interference channel with cooperating subsets of length M, the outer bound of
the total degrees of freedom is KM/(M+1). In this paper, we propose a signal
space-based interference alignment scheme that proves the achievability of
these degrees of freedom for the case K=M+2. The proposed scheme consists of a
design for the transmit precoding matrices and a processing algorithm which we
call the Successive Interference Alignment (SIA) algorithm. The decoder of each
message uses the SIA algorithm to process the signals received by the M
cooperating receivers in order to get the maximum available degrees of freedom.
