K-channel Connectivity Guarantee With Topology Control In Cognitive Radio Networks

A cognitive radio network(CRN)has the ability to sense and perceive the variation of the network according to the external environment changes and make reasonable inference and optimization based on the acquired information about the changing topology,adaptive to complete the decision of the network.It is definitely important that connectivity is essential for the information exchange between secondary users(SUs)in a cognitive radio network(CRN).In general,there exists two types of users in a cognitive radio network(CRN): primary users(PUs),and secondary users(SUs).The PUs,recycling any channel in the network at any time,possesses higher priority over the channel,while the SUs have to vacate the spectrum if they interfere with the PU.The randomness of the primary user activity easily makes the interrupt of SUs' transmission and the network division,which may result in the difficulty on the network connectivity.It has become a desiderate issue on how to make sure the strong connectivity of a cognitive network via topology control considering the activity of the PUs.As an important means to guarantee network connectivity,topology control has been unanimously recognized in the academia.There has been tremendous research on maintaining the connectivity of the network via topology control.In the traditional communication system network,high fault tolerant topology control algorithms simply guarantee the k-edge or k-vertex connectivity without considering the interference of primary users.When one primary users disturbs the cognitive radio network.There has been some related research on how to maintain the connectivity of the cognitive radio network when one channel was recycling.However,especially when multiple PUs request more than one channels simultaneously,it is an issue on how to guarantee the network connectivity in a more realistic network.Aiming at the aforementioned problems,an efficient topology control algorithm is proposed to maintain the connectivity of a cognitive network based on the network scenarios that multiple PUs request more than one channels simultaneously.The network adjusts the secondary users' transmission power and the requested channels,minimizing the channels that the network requested and conflict free.K-channel connectivity is defined to derive a CRN that remains connected whenever any k-1 channels are occupied concurrently.The core idea of the proposed algorithm: it is accomplished by ensuring that any k-1 independent sets(i.e.,groups of SUs transmitting on the same channel)are not any vertex-cut set of the CRN.In this paper,one algorithm is put forward to guarantee the network connectivity and conflict-free properties propose: centralized K-channel connectivity topology control algorithms.The centralized topology control algorithm(CKCC)consists of three phases: 1)topology construction;2)power adjustment;3)channel assignment.Finally,this paper performs simulation tests for the scheme of centralized K-channel connectivity topology control.Simulation results show that our proposed algorithms can achieve the k-channel-connectivity and minimizing the number of required channels in a conflict-free CRN as well as saving the channel spectrum resources.Moreover,the proposed algorithms economize the secondary users' transmission power,which prolong the life cycle of the network.