Research On Key Technologies Of Cooperative Spectrum Sensing In Satellite Internet Of Things

With the rapid development of mobile communication technology,the fifth-generation communication system(5G)has also been commercially available and will be laid in many cities in 2020.Compared with the fourth-generation communication system,the fifth-generation communication system has the advantages of high transmission rate,low latency,and wide connection.The Internet of Things have wider application prospect with the development of 5G.However,the development of the terrestrial Internet of Things that uses traditional cellular networks as information carriers is limited by the high construction costs and coverage capabilities.The sixth-generation communication system(6G)network extends the communication range to space,ocean,sky and land.The satellite communication network is considered to be one of the important components of 6G network.It can provide communication support for the blind coverage of the ground network.Satellite Internet of Things which use the satellite communication network as an information carrier.is an important part of the new generation of Internet of Things for 6G.Although the Satellite Internet of Things has received extensive attention from the academic circle,there is still no possibility of putting it into practical use as the Satellite Internet of Things does not have a dedicated licensed frequency band under the current spectrum allocation scheme.Cognitive radio technology can solve the above problems well.Cognitive radio technology can find idle spectrum resources and use them reasonably without affecting the normal communication of authorized users.Applying cognitive radio technology to the satellite Internet of Things can effectively solve the problem of scarcity of spectrum resources in the satellite Internet of Things.Spectrum sensing is a main part of in cognitive radio technology,which is used to discover spectrum holes.In order to detect spectrum holes more accurately,this article will study the spectrum sensing technology in the satellite Internet of Things.In terms of the contradiction between satellite being a resource-restricted unit and spectrum sensing detection performance,an optimization problem is established with the goal of optimizing perception time,and the Lyapunov optimization method is introduced to solve the long-term sequence optimization problem with time constraints.An online algorithm has been proposed to solve the above optimization problem.However,this online algorithm is inefficient.In order to improve the efficiency of solving optimization problems,a distributed alternating direction multiplier method is introduced to solve the above optimization problems.To solve the problem of poor performance of traditional cooperative spectrum sensing algorithms in the satellite communication environment,this paper proposes a semisoft-combination double-threshold oriented energy detection based spectrum sensing mechanism,which uses an optimized double-threshold decision at the local cognitive satellite and uses a membership function Represents the local judgment result,the fusion center gives each satellite different weights according to the reliability of each satellite and adds the weighted judgment results.The simulation verifies that the proposed cooperative spectrum sensing mechanism is superior to the traditional cooperative spectrum sensing mechanism in performance.