The two-user multiple-access relay channel (MARC) is investigated in the pres-ence of side information (SI) available only at the informed transmitter in thepresentarticle.First,forthediscretealphabetandmemorylessMARCwithcom-mon and private messages, partial decode and forward strategy at the relay andfixed locations of the nodes, a general achievable rate region is obtained. TheSI effect is seen and can be analyzed. Second, we extend the discrete resultto a practical communications model: Gaussian multiple-access relay channel(GMARC), showing previous works as its special cases. Third, the effect of (per-fect and nonperfect) SI on the maximum coverage region of GMARC for a fixedrate of the transmitters and a fixed distance between relay and destination isanalyzed. It is shown that the SI increases the coverage region of encoders,and consequently, it can improve communication energy efficiency. Finally,mathematical findings are validated numerically by using Matlab

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