To optimize the usage of limited spectrum resources, Cognitive Radio (CR) can be used as a viable solution. The main contribution of this paper is to propose a new protocol to increase throughput of mobile cooperative CR Networks (CRNs). The key challenge in a CRN is how the nodes cooperate to access the channel in order to maximize the CRN's throughput. To minimize unnecessary blocking of CR transmission, the authors propose a so-called New Frequency-Range MAC protocol (NFRMAC). The proposed method is in fact a novel channel assignment mechanism that exploits the dependence between signal's attenuation model, signal's frequency, and communication range and interference level.