  In this paper, we propose an achievable rate region for discrete memoryless
interference channels with conferencing at the transmitter side. We employ
superposition block Markov encoding, combined with simultaneous superposition
coding, dirty paper coding, and random binning to obtain the achievable rate
region. We show that, under respective conditions, the proposed achievable
region reduces to Han and Kobayashi achievable region for interference
channels, the capacity region for degraded relay channels, and the capacity
region for the Gaussian vector broadcast channel. Numerical examples for the
Gaussian case are given.
