# Optimal Meshing Degree Performance Analysis in a mmWave FWA 5G Network Deployment
## 3 Problem Description  
### Liverpool 5G Deployment  
The infrastructure deployed in the Liverpool 5G project is illustrated in Figure 1. In the second phase of the project (from 2020 to 2022), the network topology consisted of 220 nodes and 6 gateways (POPs) installed in the Kensington area of the city, making it among the largest standalone 5G mmWave networks in the UK and Europe. Each node in the backhaul mesh was collocated with a Wi-Fi AP to provide WLAN connectivity, with many nodes also supporting 5G small cells operating in the N77 band. The network was designed such that there is line-of-sight link along any of the roads between deployed nodes, and the connection was based on IEEE 802.11 ad mmWave links. The nodes are a mix of Blu-Wireless DN101 LC and DN201 SC stations and are attached to streetlights or other street furniture at a consistent elevation. The nodes have 90-degree azimuth coverage, one independent beam, and a maximum capacity of 5 Gbps (MAC layer). The POP nodes are connected to the gateway through a fibre link, and backhauling is then handled via a local cloud service provider. Furthermore, due to the widely deployed nodes and the high path and penetration loss at 60 GHz, some links required relays (multi-hop transmissions) to facilitate backhauling, and nodes were clustered around the nearest POP.  
The aim of this deployment is to support a range of social and healthcare applications for the Liverpool community, ranging from simple health sensor and monitoring services to VoIP, full HD or 4K streaming for remote consultations, and low-latency VR/AR tools.  
However, in the second phase of the project, many of the deployments focused primarily on providing connectivity to a small set of end user sites and, at least initially, consisted of a single POP and a number of intermediate nodes reaching toward the specific site in question, as shown in Figure 2 below. In this example, the deployment starts with the MG at node 1 (orange point in the figure) that provides POP connectivity and then extends through MRs at nodes 2 and 3 towards the end site that is connected through node 4 (blue points in the figure). Moreover, the figure illustrates the maximum Modulation Coding Scheme (MCS) and the corresponding maximum data rate that can be achieved in each link (yellow line in the figure) based on the radio environment conditions, such as path loss and transmission power, together with the corresponding maximum data rate.  
These deployments were largely governed by practical limitations, ranging from restrictions in terms of equipment and access imposed through the COVID-19 pandemic to the practical limitations of node placement around street furniture and vegetation and the 60 GHz link performance. Thus, the project represented a pragmatic solution for the project consortium and, therefore, a realistic deployment scenario for many operators in this space. However, a significant shortcoming of this approach is that each link in this deployment represents a single point of failure; moreover, each node can itself introduce traffic to the backhaul such that links closer to the POP run the risk of being overwhelmed through cumulative network load.