The satellite–terrestrial integrated networks (STINs) have gradually become a new class of effective ways to satisfy the requirements of a higher capacity and stronger connection in the future communications. In contrast with terrestrial networks, the fast periodic motion of satellites results in the dynamic time-varying features of STIN, which further leads to frequent changes in the connectivity of satellite–terrestrial links and the backhaul capacities of satellite networks. To balance the accessible capacity of STIN under the intermittent connectivity and dynamic backhaul capacity, an effective user association mechanism is needed. In this article, a dynamic user association (DUA) mechanism with task classification is proposed to meet the requirements of load balancing and the user task processing. First, a STIN model is constructed with low earth orbit satellites and the three types of base station, which are a macro base station, small cell base station, and low earth orbit based base station. After that, the optimization problem is formulated via jointly considering the task classification, the load condition of base stations, and the backhaul capacity of low earth orbit based base stations. Then, the DUA mechanism is proposed to find the most suitable base station serving each user. In DUA, a dynamic cell range extension algorithm is developed to adjust the load of STIN in terms of the resilient backhaul capacity, and a greedy-based user-centric user association with task classification algorithm is proposed to find the base station, which has the maximum rate and minimum load for each user and to meet the requirements of user task processing. The simulation results show that the proposed DUA can enhance the load balance and guarantee the task processing demand of STIN compared with the reference signal receiving power association and the max-sum rate association algorithms.

中文翻译：

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卫星-地面集成网络中弹性回程的动态用户关联

卫星地面综合网络（STIN）已逐渐成为一种新型的有效方式，可以满足未来通信中更高容量和更牢固连接的要求。与地面网络相比，卫星的快速周期性运动导致STIN具有动态时变特征，这进一步导致了卫星-地面链路的连通性和卫星网络的回程容量的频繁变化。为了在间歇性连接和动态回传容量下平衡STIN的可访问容量，需要一种有效的用户关联机制。在本文中，提出了一种具有任务分类的动态用户关联（DUA）机制，以满足负载平衡和用户任务处理的要求。第一，STIN模型是用低地球轨道卫星和三种类型的基站构建的，这三种类型的基站是宏基站，小型小区基站和基于低地球轨道的基站。此后，通过综合考虑任务分类，基站的负载情况以及基于低地球轨道的基站的回程容量来制定优化问题。然后，提出了DUA机制以找到为每个用户服务的最合适的基站。在DUA中，开发了一种动态小区范围扩展算法来根据回传容量调整STIN的负载，并提出了基于贪婪的以用户为中心的用户关联任务分类算法来查找基站，该基站具有每个用户的最大速率和最小负载，并满足用户任务处理的要求。