  We consider a problem where a memoryless bi-variate Gaussian source is to be
transmitted over an additive white Gaussian multiple-access channel with two
transmitting terminals and one receiving terminal. The first transmitter only
sees the first source component and the second transmitter only sees the second
source component. We are interested in the pair of mean squared-error
distortions at which the receiving terminal can reproduce each of the source
components.
  It is demonstrated that in the symmetric case, below a certain
signal-to-noise ratio (SNR) threshold, which is determined by the source
correlation, uncoded communication is optimal. For SNRs above this threshold we
present outer and inner bounds on the achievable distortions.
