# Analysis of Cached-Enabled Hybrid Millimter Wave & Sub-6 GHz Massive MIMO Networks

## TL;DR

This paper analyzes how edge caching in hybrid mmWave and sub-6 GHz networks affects file delivery success and latency, considering backhaul limitations, with theoretical and simulation validation.

## Contribution

It provides a stochastic geometry-based analysis of caching impact on QoS metrics in hybrid networks with practical beamforming and MIMO, highlighting backhaul capacity effects.

## Key findings

- Backhaul capacity significantly affects network performance.
- Cache size and retransmissions can mitigate backhaul limitations.
- Tradeoffs exist among cache size, retransmissions, ASP, and latency.

## Abstract

This paper focuses on edge caching in mm/{\mu}Wave hybrid wireless networks, in which all mmWave SBSs and {\mu}Wave MBSs are capable of storing contents to alleviate the traffic burden on the backhaul link that connect the BSs and the core network to retrieve the non-cached contents. The main aim of this work is to address the effect of capacity-limited backhaul on the average success probability (ASP) of file delivery and latency. In particular, we consider a more practical mmWave hybrid beamforming in small cells and massive MIMO communication in macro cells. Based on stochastic geometry and a simple retransmission protocol, we derive the association probabilities by which the ASP of file delivery and latency are derived. Taking no caching event as the benchmark, we evaluate these QoS performance metrics under MC and UC placement policies. The theoretical results demonstrate that backhaul capacity indeed has a significant impact on network performance especially under weak backhaul capacity. Besides, we also show the tradeoff among cache size, retransmission attempts, ASP of file delivery, and latency. The interplay shows that cache size and retransmission under different caching placement schemes alleviates the backhaul requirements. Simulation results are present to valid our analysis.