Research On Spectrum Allocation Algorithm In Cognitive Radio Network

Dynamic spectrum allocation algorithm is one of the key technologies of cognitive radio network.Most of the existing spectrum allocation algorithm aim at maximize the system spectrum efficiency,and do'nt consider the reduction of the number of spectrum handover,but too much spectrum handover will increase the energy consumption of nodes,but also increases the outage probability,handoff delay,packet loss rate,will make the whole system performance decline.The existing algorithms are also not taking into account the switching performance of the channel itself,the idle time length of different channel is not the same.Different users in different period needs the length of time is not the same.If you only randomly allocated of available spectrum,will cause a lot of unnecessary spectrum handover and spectrum resource waste.To solve these two problems,this paper puts forward two corresponding solving algorithms,the main work of this paper are as follows:1.At first,this paper proposes a spectrum allocation algorithm based on multi-objective genetic algorithm,the algorithm can optimize the system efficiency and the spectrum handover at the same time.This algorithm improved the traditional genetic algorithm,aim at maximize the system spectrum efficiency and minimize the number of spectrum handover,this paper mapped the solution of the problem to chromosome form,and then,according to the principle of survival of the fittest,selected more adapt to the environment of chromosome In the population,replicated,crossover,and mutated,the evolution of the generation after generation,finally get the best adapt to the environment of chromosomes,find the optimal solution of the problem.This algorithm obtained high spectrum efficiency,at the same time,effectively reduced spectrum handover.2.And then put forward a spectrum allocation algorithm based on channel characteristic and node data.We use Markov chain model to predict the channel state,and calculate the idle expectation.And then through the mechanism of coloring of graph theory choosing the most suitable idle expectation channel from all available spectrums allocate to cognitive users,achieve the goal of reduce the spectrum handover and maintain high spectrum efficiency and fairness.