Research On Satellite Optical Network Routing And Wavelength Assignment Methods

With the application of fifth-generation communication technologies and the increasing number of communication terminals,the requirements for space communication capabilities are increasing.Traditional microwave communication is susceptible to the rate and bandwidth,which makes it difficult to meet the communication needs of larger-scale satellite networks at this stage.Compared with microwave communication,satellite optical communication can use laser link for transmission,which has the characteristics of ultra-high speed,large capacity bandwidth and strong transmission stability,and is a key technology in the field of space communication.In the field of satellite optical network,Routing and Wavelength Assignment(RWA),which allocates optimal path and wavelength resources to transmit data,can meet the optimization of resource allocation for random services in dynamic network situations by reasonably and dynamically assigning routes and wavelengths according to the current overall network resources.The improvement of routing and wavelength assignment algorithm using heuristic algorithm has become a hot research topic at this stage,and the method has an important role in reducing end-to-end delay,improving communication success rate and reducing blocking rate.Based on the study of satellite optical network routing and wavelength assignment algorithms,the paper proposes heuristic RWA algorithms for low-orbiting satellite optical network,including RWA algorithm for satellite optical network with bee colony fitness optimization,RWA algorithm for multi-service QoS satellite optical network with ant colony optimization,and RWA algorithm for dynamic adaptation of network load based on genetic algorithm,which solve the problems of communication failure due to communication delay and link Doppler wavelength drift exceeding the threshold value,and the problem of communication failure for various types of services in satellite communication.The problem of communication failure due to communication delay and link Doppler wavelength drift exceeding the threshold,the problem that QoS cannot be guaranteed for all types of satellite communication services,and the problem of unbalanced services under different network loads.The main research work is as follows:(1)RWA algorithm for satellite optical network with Bee Colony Fitness OptimizationTo solve the problem of communication failure due to communication delay and link Doppler wavelength drift exceeding the threshold,the Bee Colony Algorithm with Fitness Optimization(BCAFO)RWA algorithm for satellite optical networks is proposed based on the satellite optical network routing and wavelength assignment algorithm,which combines the heuristic bee colony algorithm for optimization,the concept of total path Doppler wavelength drift is introduced to evaluate the degree of the entire path Doppler wavelength drift.The link delay and Doppler wavelength drift are introduced into the link cost function,while the fitness function is optimized to combine the total laser link length and the total amount of link Doppler wavelength drift variables and the overall congestion degree of the path.Simulations are conducted to study the three performances of the algorithm in terms of communication success rate,time delay and wavelength utilization under different service densities in the Iridium constellation and the next-generation LEO satellite constellation.The research results show that compared with the original ant colony algorithm and the original bee colony algorithm,the proposed BCA-FO algorithm has higher communication success rate,lower wavelength utilization rate,and the delay characteristics can meet the real-time service transmission requirements.(2)RWA algorithm for multi-service QoS satellite optical network with ant colony optimizationIn order to ensure the high quality transmission of various types of services of satellite communication,an Ant Colony Optimization for Multi-Service QoS(ACO-MS)RWA algorithm for satellite optical networks is proposed.The scheme divides services into high-priority realtime services and low-priority general communication class services,introduces the concept of satellite network node importance,and the realtime service heuristic function integrates wavelength availability and link length,while the general service heuristic function integrates wavelength availability,link length and node importance,so that the general service avoids the more important nodes of the network when selecting the next hop node.In the pheromone update strategy,different update strategies are adopted for different types of services,and the relatively important node resources are prioritized for real-time service use.The simulation study investigates the communication delay,overall blocking rate and wavelength utilization of the ACO-MS algorithm for real-time services in the Iridium constellation.The results show that the ACO-MS algorithm can reduce the transmission delay of real-time services at r0=0.4,compared with the Original Ant Colony Optimization Algorithm and the ACO-MS algorithm at r0=0.3,and also reduce the overall communication blocking rate and wavelength utilization of the services.(3)RWA algorithm based on genetic algorithm with network load dynamic adaptationIn order to balance the satellite network load and reduce the network congestion,the Genetic Algorithm with Network Load Dynamic Adaptation(GA-DA)RWA algorithm is proposed,which introduces the dynamic change of fitness degree and adaptive variation probability to automatically adjust the path finding strategy.The algorithm adopts dynamic fitness function according to the current network load,and dynamically changes the weights of the number of path nodes and path congestion in the function;the selection operator adopts the roulette wheel method to select and replicate individuals;the crossover operator adopts the double-point crossover method to crossover the parent chromosomes;the variation operator introduces adaptive variation probability,and dynamically adjusts the variation probability according to the current individual quality to effectively increase the population.The variation operator introduces adaptive variation probability,dynamically adjusts the variation probability according to the current individual quality,effectively increases the population diversity,finds out the optimal path under the current network load,realizes efficient service transmission and balances the network load.The simulation studies the communication blockage rate and routing hops of GA-DA algorithm in Iridium constellation and next-generation LEO satellite constellation,and the results show that GA-DA algorithm can reduce the communication blockage rate compared with the original ant colony and original genetic algorithm.