Research On Joint Power And Bandwidth Allocation Method For Inter-satellite Links Of BeiDou Navigation Satellite System

According to the "three-step" strategy of building and developing the BeiDou Navigation Satellite System(BDS),30 satellites will be launched and netted by the end of 2020,and the bds-3 will be fully completed.Compared with bds-2,one of the notable marks of bds-3 is the inter-satellite Links(ISLs)technology to realize inter-satellite interconnection.As is known to all,the power and bandwidth resources of navigation satellites are limited,so how to allocate the limited resources of satellites effectively in a certain number of inter satellite links is a practical problem worth studying.For inter-satellite links,the power and bandwidth resources allocated determine the channel capacity of the link.The joint allocation of power and bandwidth resources can not only improve the channel capacity of inter-satellite links,but also improve the utilization efficiency of on-board resources.There are two typical requirements in navigation systems: one is the sudden increase in demand,and the system channel capacity should be maximized to meet the business requirements;Second,the demand is stable,and the power and bandwidth distribution scheme should be given in a short time,so as to reduce the power consumption and maximize the energy efficiency of the system while meeting the business demand.Based on the satellite link model of bds-3 system,this paper studies the joint power and bandwidth allocation method for the two typical requirements mentioned above.The main contents are as follows: First,the model of BDS-3 intersatellite link is studied.The satellites in the bds-3 constellation are distributed in three different orbits,namely Geostationary Earth Orbit(GEO),Inclined Geosynchronous Orbit(IGSO)and Medium Earth Orbit(MEO).According to the three orbits of the allocated satellite,there are three MEO/GEO/IGSO scenarios.This part of the work includes system configuration research of beidou system,constraint conditions and dynamic characteristics of inter-satellite link,inter-satellite transmission loss research,and the use of STK toolbox to model the beidou system.Through the above work,the information of satellite link establishment and link channel conditions under any time node can be acquired in real time,which provides a necessary basis for the subsequent algorithm research.Secondly,aiming at the problems of genetic algorithm(GA)in dealing with resource allocation,such as prematurity,poor population diversity and unstable optimization performance,a combined power bandwidth allocation method based on improved GA was proposed.The algorithm is optimized to maximize the channel capacity of the system.On the premise of ensuring the global search capability of genetic algorithm,an improved population initialization generation strategy is proposed,and the roulette operator is optimized.Finally,the proposed algorithm makes a reasonable allocation of power bandwidth resources and achieves a significant increase in the total channel capacity of the system compared with the classical subgradient method.Thirdly,aiming at the need to improve the convergence speed of the algorithm when the business demand is stable,a power bandwidth joint allocation method based on improved immune genetic algorithm is proposed.The aim of this algorithm is to maximize the energy efficiency and reduce the total power consumption of the system.An improved structure of vaccine memory bank is proposed to accelerate the convergence of the algorithm.On the premise of retaining the global search ability of the improved genetic algorithm,the improved vaccine memory bank structure is used to control the direction of population evolution,so as to reduce the number of convergent iterations while ensuring the improvement of energy efficiency of the system.Simulation results show that the proposed algorithm not only improves the energy efficiency,but also reduces the convergence algebra and improves the operational efficiency.