Impact of group cooperation over competitive secondary subnetworks

In this paper, we examine dynamic spectrum sharing between several networks of licensed and unlicensed users wherein the unlicensed user subnetworks compete against other unlicensed subnetworks for spectrum access while nodes belonging to the same subnetwork cooperate with each other. In such a hostile transmission environment, we observe that spectrum sharing schemes based on the assumption of strict user conformity will not perform as well relative to cooperative schemes in which the overall performance enhancement is achieved via the collective efforts of the nodes belonging to the same subnetwork. As an example case, a cooperation scheme based on opportunistic decode-and-forward is employed in this paper in order to demonstrate the effects of intra-group cooperation in an underlay spectrum sharing network and its impact on enhancing group performance. Moreover, the effect of intra-group cooperation on other unlicensed subnetworks operating within the same geographical and spectral vicinity is studied within the context of inter-group competition for spectrum access. Our results show that those secondary systems employing group cooperation can achieve a significant advantage over the secondary systems made of fully competitive selfish users in terms of successful spectrum coexistence.