Link adaptation is an effective strategy in nature to achieve the ideal modulation to be selected depending upon signal quality at the terminals in wireless networks. In this paper, we examine the ability of the link adaptation to support cooperative transmissions. We present our proposal to improve the transmit performance within the framework of the 802.11 WLANs and discuss a switching criterion based on the best modulation which the source terminals may choose. Finally we conduct the performance evaluation and present simulation results to help understand the issues involved. For further information, please visit this web site.