Research On Satellite Time And Frequency Resource Allocation For Multitask

Satellite communication has a history of more than half a century,and it has been widely used in the navigation,military and civilian areas.With the rapid development of satellite communications,the demand of satellite missions is increasing,and the relationship of supply and demand for satellite resource is also more serious.At present,the research on satellite task scheduling is focused on observation satellites and relay satellites.The analysis of parallelism of satellite task and different satellite resources are insufficient,which is not conducive to the full and reasonable use of satellite resources.Therefore,how to manage and allocate the limited satellite resources,besides the elaborately use of satellite resource,is the key technologies and significant research direction of enhancing the performance of satellite communications systems.Based on the analysis of the resource characteristics and related constraints of tasks in satellite transponder,this paper presents a quantitative model of time-frequency resource structure of satellite transponders,also proposes some evaluation indicators including resource utilization,mission scheduling gains and transponder systems capacity and so on.The mathematical model for each evaluation index is established,and the paper also proposes optimization algorithm and simulation example for each evaluation indicator.Firstly,this paper establishes the mathematic model for the resource allocation problem of maximizing the utilization rate of transponder resources combining the mathematical two-dimensional packing problem,and the modified genetic algorithm based on surplus rectangle(MGA-SR)algorithm is proposed.The algorithm can master all the remaining resources in the process of resource allocation,and the best matching rule has been added to the algorithm,so that the unallocated tasks can select the resources with the closest task requirements.This part of the algorithm can reduce the useless resource debris,and the simulation results show that the MGA-SR algorithm can reach about 99% of the resource utilization in the allocation of resources for random tasks.Secondly,the paper takes the priority and time window into account,and proposes the mathematical model for scheduling revenue.This paper considers the time window and bandwidth at the same time,then establishes the time-frequency window as the resource pool to be allocated,so that the ant colony optimization based on time and bandwidth algorithm(ACO-TB)has been proposed.This algorithm combines the task priority and scheduling flexibility into the heuristic information of the ant colony algorithm,and adds the pseudo-random state transition rule which adjusts the proportion of colony random search in real time.The simulation results show that ACOTB algorithm has significant advantages compared with genetic algorithm and heuristic algorithm in algorithm results,optimization ability and stability.Finally,this paper aims at the intermodulation interference caused by the non-linear amplifier in the transponder,and takes the maximum system capacity as the objective function in order to find the best carrier sort in the frequency range of the transponder.In the paper,the theoretical calculation method of intermodulation interference and thermal noise in transponder are given,and a genetic algorithm of carriers sort(GA-CS)algorithm is proposed.The simulation part gives two kinds of experimental types which is unequal bandwidth and unequal power to verify the algorithm performance,and the simulation results show that the algorithm is superior to the heuristic algorithm in terms of system capacity,signal to interference plus noise ratio and noise power.