Heterogeneous cellular networks (HetNets) are one of the key enabling technologies for fifth generation (5 G) networks. In HetNets, the use of small base stations (SBSs) inside the coverage area of a macro base station (MBS) offers higher throughput and improved coverage. However, such multi-tier base station deployment introduces new challenges, e.g., (i) All users experience significant inter-cell interference (ICI) due to frequency reuse, (ii) SBS associated users experience severe MBS-interference due to higher MBS transmit power, and (iii) MBS coverage edge users receive lower signal-to-interference ratio (SIR) due to longer distances. To address the aforementioned challenges, this work proposes a framework, including a novel cell deployment strategy, which combines Stienen's model with soft frequency reuse (SFR) and the corresponding performance analysis. According to Stienen's cell based SBS deployment, SBSs are deployed in MBS coverage edge area to enhance downlink SIR. To further mitigate ICI and MBS-interference, SFR is employed along with Stienen's cell based SBS deployment. Based on stochastic geometry, we derive expressions for coverage probability with four different types of cell deployment and SFR employment combinations. Numerical results indicate that SFR-enabled Stienen's cell based SBS deployment leads to enhanced edge user coverage and, hence, improves network performance gain.

中文翻译：

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在两层异构网络中启用软频率复用和Stienen的小区划分：小区部署和覆盖率分析

异构蜂窝网络（HetNets）是第五代（5 G）网络的关键启用技术之一。在HetNets中，在宏基站（MBS）的覆盖区域内使用小型基站（SBS）可以提供更高的吞吐量并改善覆盖范围。然而，这样的多层基站部署带来了新的挑战，例如，（i）所有用户由于频率复用而遭受严重的小区间干扰（ICI），（ii）与SBS相关的用户由于较高的MBS发射而遭受严重的MBS干扰。电源；以及（iii）MBS覆盖边缘用户由于距离较长而收到的信噪比（SIR）较低。为了解决上述挑战，这项工作提出了一个框架，其中包括结合了Stienen' 的模型具有软频率复用（SFR）和相应的性能分析。根据Stienen基于小区的SBS部署，SBS被部署在MBS覆盖边缘区域中，以增强下行链路SIR。为了进一步减轻ICI和MBS干扰，SFR与Stienen基于小区的SBS部署一起使用。基于随机几何，我们推导了四种不同类型的单元部署和SFR雇佣组合的覆盖概率表达式。数值结果表明，启用SFR的Stienen基于小区的SBS部署可增强边缘用户的覆盖范围，从而提高网络性能。SFR与Stienen基于小区的SBS部署一起使用。基于随机几何，我们推导了四种不同类型的单元部署和SFR雇佣组合的覆盖概率表达式。数值结果表明，启用SFR的Stienen基于小区的SBS部署可增强边缘用户的覆盖范围，从而提高网络性能。SFR与Stienen基于小区的SBS部署一起使用。基于随机几何，我们推导了四种不同类型的单元部署和SFR雇佣组合的覆盖概率表达式。数值结果表明，启用SFR的Stienen基于小区的SBS部署可增强边缘用户的覆盖范围，从而提高网络性能。