Research On Spectrum Allocation Algorithm Based On OFDMA Femtocell

With the rapid development of information technology,users have increasing requirements of high-speed datatraffic and the spectrum resources has become a key factor in the development of communications.Therefore,the rational allocation of spectrum resources is essential.Various spectrum allocation techniques have been widely studied,among which dynamic spectrum resource management is a research hotspot.Femtocell base supports higher data ratesand using free channel spectrum resources both inmacro cellular networks and femtocellnetworks is the currentresearch direction.This paper analyzes the relationships between spectrum allocation algorithm and graph theory and applies the coloring theory of graph theory to the spectrum allocation of OFDMA downlink.In order to reduce the interference of the same layer,the undirected interference topological formed is colored and clustered.In the femtocellnetwork with access technology of OFDMA(Orthogonal Frequency Division Multiple Access),it proposes marcocell and femtocelldual-layer network architecture and proposes an adaptive spectrum resource allocation scheme using the constraint genetic algorithm.It proposes two spectrum allocation strategies on how to makemodeling in allocating spectrum resource and how to analyze the service quality of the network.In the OFDMA femtocellnetwork,it proposes an adaptive spectrum resource allocation scheme using the constraint genetic algorithmbased on the number of users in the cluster.It establishes objective function in corresponding with user number and it updates population iteratively to realize the optimal allocation of spectrum resources.The simulation results of MATLAB show that allocated bandwidth changes with user demand curve,which improves user experience and avoids waste of spectrum resources.Based on the difference of the number of users in the base,an adaptive spectrum resource allocation scheme based on user demand is proposed.The service type of each user in the base station is quantized and an objective function is established.The results of MATALB simulation show that the bandwidth allocated by each base basically changes with user requirements.The spectrum resource allocation scheme based on userdemand is further improved compared with spectrum resource allocation scheme based on the number of users.It further improves user experience and achieveshigh efficiency of spectrum resources.In the OFDMA femtocellnetwork,this paper studies ahybrid spectrum access scheme.With consideration of co-tier interference and cross-layer interference when femtocell basesare intensive deployted in the OFDMA downlink transmission,it uses graph coloring theory to reduce the interference of adjacent femtocell bases.Simulation results show that it improves network efficiency and network throughput.The resource allocation algorithm proposed can improve user service quality,improve spectrum utilization and improve fairness.It is of practical significance to realize the reasonable allocation of spectrum resources in femtocell network.