A large number of previous works have demonstrated that cooperative spectrum sensing (CSS) among multiple users can greatly improve detection performance. However, when the number of secondary users (SUs; i.e., spectrum sensors) is large, the sensing overheads (e.g., time and energy consumption) will likely be intolerable if all SUs participate in CSS. In this paper, we proposed a fully decentralized CSS scheme based on recent advances in consensus theory and unsupervised learning technology. Relying only on iteratively information exchanges among one-hop neighbors, the SUs with potentially best detection performance form a cluster in an ad hoc manner. These SUs take charge of CSS according to an average consensus protocol and other SUs outside the cluster simply overhear the sensing outcomes. For comparison, we also provide a decentralized implementation of the existing centralized optimal soft combination (OSC) scheme. Numerical results show that the proposed scheme has detection performance comparable to that of the OSC scheme and outperforms the equal gain combination scheme and location-awareness scheme. Meanwhile, compared with the OSC scheme, the proposed scheme significantly reduces the sensing overheads and does not require a priori knowledge of the local received signal-to-noise ratio at each SU.cognitive radio networks, spectrum sensing, decentralized clustering, unsupervised learning, consensus theory
Citation:Wu Q H, Ding G R, Wang J L, et al. Consensus-based decentralized clustering for cooperative spectrum sensing in cognitive radio networks. Chin Sci Bull, 2012Bull, , 57: 36773683, doi: 10.1007 In cognitive radio networks (CRNs), secondary users (SUs) opportunistically exploit spectrum holes [1] left by primary users (PUs) to improve utilization of the wireless spectrum. To determine the temporal or/and spatial spectrum holes, a main challenge is reliable and efficient spectrum sensing. Compared with the single-SU spectrum sensing methods [2], cooperative spectrum sensing (CSS) among multiple SUs can be employed to tackle the problem of hidden primary receivers [3] and wireless channel fading (e.g., shadowing and multi-path fading) [4] by exploiting multi-user spatial diversity [5]. There have been recent comprehensive surveys on CSS in the literature [6,7]. In terms of whether a fusion center exists, previous works can be mainly classified as those on centralized CSS and those on decentralized CSS. A number of centralized CSS techniques have been proposed, including methods of hard combination [8][9][10], soft combination [11,12] and quantized combination [13]. To further reduce sensing overheads (e.g., time and energy consumption) and improve the network scalability and robustness, there has been a recent focus on the design of decentralized CSS schemes. Decentralized CSS has been modeled as an evolutionary game in which each SU learns its best strategy (to collaborate or not) from strategic interactions with other SUs [14]. The network [14] is a single-hop network; i.e., each SU directly exc...