To overcome the adverse effects of wireless channel, cooperative communications is the practical implementation of Multiple-Input-Multiple-Output (MIMO) concept in size constraint nodes. To exploit the benefits of cooperative transmission properly, we use the block-Markov encoding. Recently, an operational implementation of this information theoretic coding strategy, using network coding, has been proposed. In this paper, we give the achievable diversity and the multiplexing tradeoff curve for the proposed network coding based cooperative communications. With numerical results, we show that the cooperative transmission using network coding outperforms both the repetition and the space-time (ST) coding based cooperative communications, in terms of diversity-multiplexing tradeoff.