To alleviate the backhaul congestion in future hybrid heterogenous networks, this paper investigates the potential benefits of implementing storages in small base stations (SBSs) operating at frequency range 2 (FR2) bands that co-exist with a tier of massive multiple input multiple output (MIMO) macro BSs (MBSs) operating at frequency range 1 (FR1) bands. We develop a unified analytical framework and derive theoretical bounds for such a cache-enabled FR1–FR2 hybrid network under limited backhaul scenario to analyze the exact and approximate latency, average success probability of file delivery, and average data rate considering two open-access user association policies: i) location-based and ii) content-based association. Numerical results demonstrate that wireless edge caching (WEC) can improve the performance of hybrid wireless networks, albeit certain trade-offs, e.g., increasing cache-enabled SBSs cannot always improve the network performance and there exists an optimal SBS density that provides the best latency and throughput performance. Furthermore, we compare the performance of the network with respect to other key network design parameters such as cache size, content popularity, backhaul capacity, and blockages for both the user associations. Our results show that latency under content-based user association is less than that of location-based user association, and although the difference in the average rates under the two user associations is not obvious, content-based association can extricate more backhaul capacity and thus reduce installation cost significantly.

中文翻译：

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关于启用缓存的混合无线网络的性能

为了减轻未来的混合异构网络中的回程拥塞，本文研究了在工作于2级频率（FR2）频段的小型基站（SBS）中实现存储的潜在好处，这些存储与一层大量的多输入多输出共存（ MIMO）宏BS（MBS）工作在频率范围1（FR1）频段。我们开发了一个统一的分析框架，并在有限的回程情况下得出了这种启用了缓存的FR1-FR2混合网络的理论界限，以分析精确和近似的延迟，考虑两个开放访问用户的平均文件传输成功率以及平均数据速率关联政策：i）基于位置的关联； ii）基于内容的关联。数值结果表明，无线边缘缓存（WEC）可以提高混合无线网络的性能，例如，增加启用缓存的SBS不能总是改善网络性能，并且存在提供最佳延迟和吞吐量性能的最佳SBS密度。此外，我们将网络性能与其他关键网络设计参数（例如，两个用户关联的缓存大小，内容受欢迎程度，回程容量和阻塞）进行了比较。我们的结果表明，基于内容的用户关联下的等待时间比基于位置的用户关联下的等待时间要短，尽管两个用户关联下的平均速率差异并不明显，但基于内容的关联可以释放更多的回传容量，因此大大降低安装成本。