Research On Spectrum Allocation Algorithm Based On Graph Coloring Theory In Cognitive Radio

The wireless spectrum belongs to non-renewable resources, how to improve theutilization of spectrum resources has been the most important issue in thedevelopment of wireless communication technologies. The traditional way to solvethis problem is to use advanced communication theory and technologies, but this cannot fundamentally solve the problem of spectrum scarcity because of Shannontheorem. With the rapid growth of wireless communication technologies, thecontradiction between supply and demand of spectrum resources has been more andmore intense and has became the bottleneck in the development of wirelesscommunication technology. Cognitive radio comes into being.Cognitive radio as an effective mean to improve the utilization of spectrumresources, has been paid more and more attention. Extensive study on cognitive radioworldwide, making this field of research and development speed has been improved.Spectrum resources can be full used by cognitive radio through secondary use of helicensed spectrum, the utilization of spectrum has been improved and scarcity ofspectrum has been relieved. Cognitive radio is considered to be the most popularwireless communication technology.Dynamic spectrum allocation is one of the key technologies of cognitive radio. Auseful dynamic spectrum algorithm can effectively improve the efficient use ofspectrum resources, the flexibility use of the spectrum, the throughput of the system.Dynamic spectrum algorithm has therefore become a hot research of cognitive radio.This paper mainly researches on the spectrum allocation based on graph coloringtheory in cognitive radio. The concept of cognitive radio and its development statusare first introduced. Then the key technologies are analyzed and four commonly usedmodels of the dynamic spectrum allocation algorithm are introduced. Then theexisting algorithms based on the graph coloring theory model are introduced:list.coloring algorithm, CSGC algorithm and parallel algorithm. After completion of a cycle of spectrum allocation, to the time before the nextround of spectrum allocation, if the position of a node has been changed so thecorresponding parameters，the other cognitive users must be affected by reallocationof spectrum and reallocation also cost more time. Based on the CSGC algorithm, thesingle node position changing spectrum allocation algorithm is proposed to solve theproblem. The simulation results show that the improved algorithm is similar withreallocation in terms of performance but costs less time spending.Different users have different purposes by using spectrum, the cognitive usersare divided into ordinary users and special users. A improved algorithm is given toensure that the advanced users’ needs must be met and the common users’ needsshould be met as much as possible. The simulation results show that the improvedalgorithm not only ensures that the advanced users can communication normally butalso better meets the needs of ordinary users, spectrum utilization is improved andspectrum allocation is more rationalization.