—In this paper, with the cross-layer design principle, a novel cooperative triple busy tone multiple access (CTBTMA) scheme is proposed for wireless networks to achieve cooperative diversity gain. A utility-based algorithm is presented to determine the capability of a node in helping other nodes’ transmissions. With the use of three busy-tone channels, not only collisions can be avoided, but also an optimal helper can be determined without disturbing existing transmissions. Simulation results demonstrate that the proposed scheme can effectively increase the throughput in a low SNR environment, as compared with IEEE 802.11a single-hop transmissions. On the other hand, transmit power can be greatly reduced in the proposed scheme in order to achieve the same throughput as in the single-hop transmissions.