Cooperative vs. non-cooperative: Self-coexistence among selfish cognitive devices

Cognitive networks address the spectrum shortage problem exploiting unused chunks of the frequency spectrum, i.e. channels. With the aim to opportunistically use these channels, cognitive devices (CDs) have been defined. We propose two game theoretic frameworks with the peculiarity of capture the interactions between selfish CDs exhibiting both non-cooperative and cooperative behaviors. The first framework is formulated as a multi-player Non-cooperative Repeated game (NoRa), which is treated as a potential game. The second framework is a Hedomc Coalirional Formation game (HeCtor) characterized by cooperation among CDs that belong to the same coalition (i.e., a sub-group of devices). Extensive experiments demonstrate that cooperation among CDs increases network throughput, however, when licensed users change their transmission parameters quickly, the performance gain is comparable to that of the non-cooperative framework because of the faster adaptability that characterizes the non-cooperative framework as compared to the cooperative one.