Research On Blind Channel Hopping Rendezvous Technology In Heterogeneous Cognitive Radio Networks

With the proposal of cognitive radio technology,cognitive users can dynamically access the licensed channels not occupied by primary users on the premise of guaranteeing the communication quality of primary users.Therefore,the utilization efficiency of spectrum resources is greatly improved.In a heterogeneous multi-channel cognitive wireless network,considering that each cognitive user has different capabilities of spectrum sensing and the dynamic occupation of frequency bands by primary users,the available idle channels of cognitive users are often different from each other.Therefore,the sender and receiver must exchange control information such as the used channel,transmission time,and transmission rate before communication.In the existing research on cognitive wireless networks,there are three commonly used technologies for exchanging control information: common control channel technology,grouping technology,and channel hopping technology.The first two need to select a fixed channel as the control channel,but the fixed control channel is prone to channel saturation.The blind channel hopping rendezvous technology means that each cognitive user generates channel hopping sequence independently,without a fixed public control channel or relevant information of other cognitive users.The antennas equipped by cognitive users access the channel according to the locally generated channel hopping sequence.When accessing the same licensed channel at the same time,they can achieve blind rendezvous and exchange control information.Compared with ordinary non-blind channel hopping rendezvous technology,the blind channel hopping rendezvous technology effectively saves time and space costs.The channel hopping rendezvous technology can distribute the load of control information to different channels,so as to avoid the problem of control channel saturation more effectively,and can better deal with the dynamic occupancy of channel by primary users.Therefore,this thesis conducts an in-depth study on the blind channel hopping rendezvous mechanism of heterogeneous cognitive radio network.Based on the mathematical theory of relaxed cyclic difference sets,the CL-CH sequence and the ID-CH sequence are proposed.The two channel hopping sequences are suitable for asynchronous clocks.Compared with ID-CH sequence,CL-CH sequence is an anonymous mode,which can effectively protect the privacy of cognitive users.When the cognitive radio network does not have a unified standard for channel division of licensed spectrum or the number of cognitive users in the network is small,the ID-CH sequence is more practical than the CL-CH sequence.In these two sequences,considering that the cognitive user has continuous available channels or discontinuous available channels,different channel traversing algorithms are proposed based on a special relaxed cyclic difference sets,so as to shorten the time to redezvous between cognitive users as much as possible.We analyze the upper bounds of time(i.e.MTTR-FC and MTTR-AC)that guarantee the rendezvous between any two cognitive users.Then,a large number of simulations are carried out on the Matlab platform.The results show that our analysis is correct and the two sequences in this thesis obtain smaller MTTR-FC and MTTR-AC values than the existing similar channel hopping sequences.