联合解耦上/下行链路级联和跨层双连接入技术的三层异构网设计和覆盖概率分析

研究了跨层双连接(dual-connectivity， DC)3层异构网络(heterogeneous network， HetNet)中上行链路(uplink， UL)和下行链路(downlink， DL)解耦级联(decoupled UL and DL association， DUDA)设计和网络覆盖概率问题。在该跨层DC DUDA模型中，一个用户的DL或UL同时与位于不同层的最佳和非最佳基站(base stations， BSs)级联，并且DL的接入基站可能与UL的不同。对此网络，获得了各种可能的跨层DC DUDA实现方案;利用实际的功率约束简化了每种案例的级联条件，获得了级联概率闭式解;利用随机几何方法获得了网络的覆盖概率。数值和仿真分析了系统参数对级联概率的影响，比较了耦合和解耦模型的级联概率和覆盖概率，发现提出的DUDA DC模型优于传统的耦合的UL/DL级联(coupled UL and DL association， CUDA)DC模型;给出了覆盖概率的数值分析和仿真比较，验证了文章所得结论。

Designs and coverage probabilities of three-tier hetnets jointing decoupling UL/DL association and cross-tier dual-connectivity

This paper focuses on the decoupling uplink (UL) and downlink (DL) association (DUDA) in the cross-tier dual-connectivity (DC) three-tier heterogeneous network (HetNet) as well as coverage probabilities. In such novel HetNet jointing cross-tier DC and DUDA, a typical user equipment (UE) is in DL or UL associated simultaneously with the optimal and non-optimal base stations (BSs) located in different tiers. At the same time, because of the employment of decoupling association techniques, the UL has different access BSs from DL. For such novel three tier HetNets, the work first presents a comprehensive investigation on the cross tier DC design of all possible DUDA modes and the corresponding association conditions. Secondly, by simplifying the association conditions with the aid of practical power constraint, the work obtains the closed form expressions of association probabilities. Finally, the work derives the average coverage probability of the entire HetNet. The numerical analysis and simulation first present the impact of network parameters on derived association probabilities and the comparison between decoupling and coupling schemes. It is found that the proposed DUDA DC scheme outperforms the traditional coupling UL/DL association (CUDA) DC one. Secondly, the comparison of coverage probabilities between numerical results and simulations validates the derivations.