  This paper considers the problem of transmitting the difference of two
jointly Gaussian sources over a two-user additive Gaussian noise multiple
access channel (MAC). The goal is to recover this difference within an average
mean squared error distortion criterion. Each transmitter has access to only
one of the two Gaussian sources and is limited by an average power constraint.
In this work, a lattice coding scheme that achieves a distortion within a
constant of a distortion lower bound is presented if the signal to noise ratio
(SNR) is greater than a threshold. Further, uncoded transmission is shown to be
worse in performance to lattice coding methods. An alternative lattice coding
scheme is presented that can potentially improve on the performance of uncoded
transmission.
