Multi-user Regional Dynamic Distribution Beam Selection And Access Strategy Based On Position And Power Fusion Decision

Low-earth-orbit(LEO)satellite communications can break through the restrictions of the terrain and the surface and truly realize the "ubiquitous connection" of the whole world.Recently,it has attracted widespread attention at home and abroad.The power distribution in the LEO satellite beam cell is uniform,the transmission time delay is large,and the network topology is dynamic and changeable.The cell selection and access strategy in the existing communication system are no longer applicable to the LEO satellite network system.LEO satellite network user behavior characteristics are complex,the distribution of time and space of trafic is not uniform,in order to provide network services to users at any place and any time,the LEO satellite network needs to provide access capability under the dynamic distribution of multiple users,which needs to break through three key problems,such as traffic modeling,beam selection and access control.The existing traffic models are mainly constructed according to specific networks,and their distribution is closely related to the characteristics of specific networks,so they are not suitable for complex LEO satellite networks.This paper first studies the application scenarios and traffic requirements of LEO satellite network,and then constructs a multi-level network traffic model based on spatio-temporal correlation and Markov transition,and establishes a reasonable network trafic model reflecting the dynamic distribution of multiple users.Finally,compared with the traffic data obtained by Galaxyspace,the model can well reflect the LEO satellite network traffic characteristics.Aiming at the problem of low accuracy of beam selection based on power,the paper first studies the measurement start-up scheme of users in LEO satellite network,then adds the user's position as the main factor to the decision of beam selection,and proposes a beam selection algorithm based on position and power fusion decision,which can realize beam selection more accurately and reduce beam selection frequency effectively.LEO satellite has wide beam coverage and large transmission delay,which will require longer access processing time and access response waiting time,in order to reduce the access delay,this paper proposes a two-step access process for LEO satellite network.Based on the traffic model and beam selection,the user distribution and beam selection power threshold are determined,and an improved comprehensive weighted access algorithm supporting global coverage is proposed.The algorithm realizes multi-user dynamic distribution of access requests,and can significantly reduce the call blocking and call interruption of the system.And the influence of weighting coefficient on access performance is analyzed.Finally,a system level simulation platform of STK and OPNET is built to verify the performance of the proposed beam selection algorithm based on position and power fusion decision and the performance of the improved weighted access algorithm based on fusion traffic model and beam selection.