10. An Improved Grouping Spectrum Allocation Algorithm in Cognitive Radio

In cognitive radio network, a Grouping spectrum allocation algorithm allocates lots of spectrum to cognitive users, but not to care for the users’ requirement, which leads to unreasonable spectral allocation. For this problem, this paper proposes an improved Grouping algorithm based on users’ requirement. According to the graph theory, the topology of network is divided into many groups by two different grouping ways (frequency Grouping and user Grouping) respectively. In the distributing process, each group reports the distributed information after completing one distribution. Whenever a user’s demand is satisfied, every group is informed to not allocate the spectrum for the user any more, and delete it from the topology in every group at the same time. The improved method can get high spectrum utilization with little sacrifice of time that cost on the spectrum allocation. In addition, the fairness is improved by deleting the node whose demand had already been met. Because of doing this, the other nodes being interference with the node on the same channel can participate into spectrum allocation. The simulation result proves that the utilization of the improved algorithm is much higher than the traditional parallel algorithm, and users’ satisfaction increases a lot.