Abstract: This letter addresses the joint subcarrier and power allocation problem in downlink multiuser OFDM cooperative networks. The sum of the logarithmic per user time-averaged bits-per-Joule is maximized. The optimization problem is decomposed into two subproblems. First, the solution for the subcarrier allocation considering the proportional fairness is obtained. Second, an alternating power allocation (PA) scheme with separate transmit power constraints at the source and relays is derived under frequency selective fading channels. Then the complexity of the proposed scheme is analyzed. Finally, numerical results present the convergence, energy efficiency and outage probability performance of the proposed scheme.