异构蜂窝网络中QoS感知的负载平衡方案设计

鉴于异构蜂窝网络（Heterogeneous cellular network，HCN）的自身特性，传统最强信号接入（小区选择）方式已不再适合，新型小区选择方案急需引入。不同于传统接入方案，新型方案应具备平衡各类基站负载的能力。为反映用户资源消耗水平与实现平衡网络负载的目的，设计了一个服务质量（Quality of service，QoS）感知的负载平衡方案。该方案以资源消耗量作为基站负载，且同时拟合了用户服务质量需求。最终，该方案被规划为网络加权效益最大化问题。从规划问题的形式来看，该问题为非线性、混合整数优化问题，因此求解其最优解富于挑战性（尤其针对大规模问题）。为解决该问题，尝试利用对偶分解法设计了一个分布式算法。仿真结果表明，相比于最强信号接入和区域拓展接入，提出的接入方案具有更高的负载平衡水平与更低的呼叫阻塞概率。

Design of QoS-Aware User Association for Load Balancing in Heterogeneous Cellular Networks

Considering that the conventional associations may not be appropriate due to the special characteristics of heterogeneous cellular networks (HCNs), some novel associations that can balance the network loads should be designed. To reflect the resource consumption levels of users and balance loads, a QoS-aware user association is proposed for load balancing in HCNs. In the association, the load is defined as the amount of consumed resources, which can reflect the resource consumption levels of users. Finally, this scheme is formulated as a network-wide weighted utility maximization problem. That is a nonlinear mixed-integer optimization problem, and obtaining its optimal solutions is very challenging (especially for large-scale problems). To solve the problem, a distributed algorithm is designed using dual decomposition. Numerical results show that, compared with the best power association and range expansion association, the proposed scheme has higher load balancing levels and lower call blocking probabilities.