Source coding and channel coding are two important parts of a communications system. Source coding deals with the compression of source data, while channel coding adds some redundancy to circumvent the channel errors. Source coding and channel coding can be done either jointly or separately depending on the design issues like complexity of the system, rate, power, distortion tradeoffs. For optimal performance, all the parameters should be carefully chosen and optimized. This thesis looks at the scenarios of multi-terminal communications model where source and channel separation will not degrade the performance of the system in terms of rate power and distortion tradeoffs. Specifically, we investigate the transmission of data from correlated sources over an orthogonal multiple access channel under a total power constraint. It is observed that source-channel separation in this particular scenario is possible without any loss in the performance of the system. For the correlated sources case of the multiterminal communications, we provide an alternate approach for achieving source-channel separation.