Aggregation of resources in space, spectrum, and so on, is the fundamental idea behind many technology building blocks of 5G networks, such as massive multi-input multi-output and carrier aggregation, among others. In this respect, another important dimension for parallelism is the aggregation of diverse radio access technologies (RATs), such as WiFi, LTE, and 5G, in heterogeneous networks (HetRAT networks). Simultaneous multiple RAT connectivity facilitates both users and network operators in achieving even higher data rates and in balancing the traffic load, respectively. In this paper, we review the technological supports for the realization of the multi-RAT connectivity and focus on a general framework for resource allocation in HetRAT systems. Specifically, a distributed algorithm is proposed to allocate, with minimal overhead signaling, the bandwidths of available RATs among users considering both the system operator’s objective and the users’ demands and constraints. The optimality of the proposed distributed algorithm is further proved, and its convergence is investigated. Finally a test case is introduced in which users are power constrained and the system operator enforces capacity limits and motivates users for a fair load balancing over RATs. Numerical results shows the efficiency of the proposed algorithm and its fast convergence in few iterations.

空间，频谱等方面的资源聚合是5G网络许多技术构建块背后的基本思想，例如大规模的多输入多输出和载波聚合等。在这方面，并行性的另一个重要方面是异构网络（HetRAT）中各种无线接入技术（RAT）的聚合，例如WiFi，LTE和5G网络）。同时的多个RAT连接可帮助用户和网络运营商分别获得更高的数据速率和平衡流量负载。在本文中，我们回顾了实现多RAT连接的技术支持，并重点介绍了HetRAT系统中资源分配的通用框架。具体地，提出了一种分布式算法，以考虑系统运营商的目标以及用户的需求和约束，以最小的开销信令在用户之间分配可用RAT的带宽。进一步证明了所提出的分布式算法的最优性，并研究了其收敛性。最后，引入了一个测试用例，在该用例中，用户受到功率限制，系统操作员实施容量限制并激励用户在RAT上实现合理的负载平衡。数值结果表明，所提算法的效率高，迭代次数少。