Optimization Of NOMA User Grouping And Power Allocation Algorithm In Terrestrial Satellite Integrated Network

With the fast growth of wireless communication technology,various new services are constantly emerging,and the accompanying explosive growth of data traffic poses a huge challenge to the performance of wireless communication systems.At the same time,the rapid development of the Internet of Things also makes the number of terminal equipment access a trend of rapid growth,and the capacity performance of the current communication system needs to be improved urgently.Based on the existing problems,the Non-Orthogonal Multiple Access technology is proposed.NOMA breaks the constraints of the previous Orthogonal Multiple Access technology and converts a resource block into a single resource block.It is allocated to multiple users at the same time,and other indicators are used to distinguish users,which improves spectrum utilization and has great advantages for massive user access.For the new generation of mobile communication systems,it is also necessary to pay attention to the issue of global regional user coverage,so that users in harsh environments can also obtain better quality services.In this regard,satellite systems are given great expectations and affim.At present,a Terrestrial Satellite Integrated Network is proposed,which combines satellites and ground base stations to interact through the cloud center to jointly serve users.In the thesis,NOMA technology is applied to TSIN network,focusing on the grouping of users and power distribution in the system,in order to further improve the system performance.In the thesis,the downlink TSIN system model based on NOMA technology is established,and the signal models of ground users and satellite users are given.With the goal of maximizing the capacity performance of the network system,the function model of the optimization problem is given,and it is decomposed into users.Set allocation,grouping of base stations and satellite users,and user power allocation are three suboptimization problems.Next,the channel condition ratio of the user relative to the base station and satellite to which it belongs is defined,and the allocation scheme of the user set is proposed accordingly.In order to ensure the effective pairing of NOMA users,appropriate user grouping algorithms are proposed for base station service users and satellite service users respectively.For base station users,starting from the two main grouping ideas of matching idea and clustering idea,the problem is modeled as bipartite graph and biclustering problem,and the Kuhu-Munkres algorithm and variable neighborhood algorithm are used to solve the problem respectively.The performance of the algorithm is pros and cons.For satellite users,a dynamic grouping scheme of satellite users is designed.By constructing the relationship model between user elevation angle,beam angle and distance,the satellite service area is partitioned,so that the grouping basis is changed from user characteristics to fixed environmental properties.Therefore,the algorithm has a good tolerance for the time-varying of the earth-satellite communication link.Finally,according to the performance optimization requirements of the system,the optimal expression of the user power allocation factor is deduced,and the power allocation problem of base station users and satellite users is solved by successive convex approximation method and Lagrangian dual algorithm,and the system is given.Joint scheme for overall power distribution.Compared with the traditional scheme,the user grouping and power allocation scheme presented in the thesis improves the system capacity and performance.