Research On Resource Scheduling Strategy For Beam Hopping In LEO Communication Constellation

Low Earth Orbit(LEO)communication satellites can break through terrain constraints and work with 5G(fifth-generation mobile communication standards)to build a space-ground integrated information network to provide communication services for global users.LEO satellites run at a fast speed,so the link status between users and satellites changes frequently,and link allocation affects system performance.Faced with diverse business scenarios,beam-hopping technology can allocate resources more flexibly,and full-frequency multiplexing improves spectrum utilization,but there is serious co-channel interference.Addressing the above problems and aiming at maximizing system service capability and resource utilization rate,this paper conducts research on the beam-hopping beam position selection strategy and space-time resource allocation strategy of low-orbit satellite constellations.First of all,for areas where the communication capacity of the satellite network is insufficient,on the premise of known constellation and gateway station deployment,in order to maximize the number of continuous service cells in the area to be planned,a beam position selection strategy combining random selection and least visible priority criterion is proposed.When performing user link allocation,first randomly select cells to start allocating resources;then for each beam hopping cycle,select the satellite with the fewest visible cells to establish a link.Due to the full consideration of the subsequent cell selection space,the strategy proposed in this paper improves the beam utilization to a certain extent.The simulation results show that this strategy has a higher cell service rate under the condition of satellite configuration with different beam numbers.When the beam number is 40,compared with other solutions,the number of serviceable cells can be increased by 13.3% to 34.7%.After the link establishment relationship between the satellite and the cell in each beam hopping period(BHP,Beam Hopping Period)in the constellation is determined,when knowing the service beam position required by each satellite,in terms of the beam scheduling problem of a single satellite for fixed terminals on the ground,a beam scheduling strategy that can achieve dual optimization of interference and delay is proposed.The model with the optimization goal of minimizing the queuing delay and co-channel interference is constructed,combining with constraints such as transmit power as well as carrier-to-interference ratio.By the means of step-by-step optimization,a beam-hopping scheme including demand clustering,time slot allocation and beam position matching is designed.When it comes to the interference optimization problem in the beam position matching process,a genetic algorithm-based chromosome crossover mechanism of "beam position self-crossover within a cluster" is proposed.The simulation results show that the improved genetic algorithm can reduce the cochannel interference by 35% to 60% compared with the other algorithm.Besides,the proposed strategy can schedule the beam within the resource allocation period while achieving dual optimization of delay and interference.