  Zero-delay transmission of a Gaussian source over an additive white Gaussian
noise (AWGN) channel is considered in the presence of an additive Gaussian
interference signal. The mean squared error (MSE) distortion is minimized under
an average power constraint assuming that the interference signal is known at
the transmitter. Optimality of simple linear transmission does not hold in this
setting due to the presence of the known interference signal. While the optimal
encoder-decoder pair remains an open problem, various non-linear transmission
schemes are proposed in this paper. In particular, interference concentration
(ICO) and one-dimensional lattice (1DL) strategies, using both uniform and
non-uniform quantization of the interference signal, are studied. It is shown
that, in contrast to typical scalar quantization of Gaussian sources, a
non-uniform quantizer, whose quantization intervals become smaller as we go
further from zero, improves the performance. Given that the optimal decoder is
the minimum MSE (MMSE) estimator, a necessary condition for the optimality of
the encoder is derived, and the numerically optimized encoder (NOE) satisfying
this condition is obtained. Based on the numerical results, it is shown that
1DL with non-uniform quantization performs closer (compared to the other
schemes) to the numerically optimized encoder while requiring significantly
lower complexity.
