Case Study: The American Digital Village
The expanded range opens up new opportunities for using mmWave spectrum in sparse suburbs and semi-rural areas, which then makes it possible to unload lower frequencies. In such areas, there can be several hundred homes per sector. With increased consumption on both MBB and FWA, the additional capacity provided by mmWave makes such a scenario a good point to combine mmWave and midband TDD, providing FWA subscribers with high service levels.
In the following simulation scenario, representing the performance achieved in field trials, we demonstrate how the mmWave extended range can be used to increase capacity and enhance user experience. The case is a copy of the Digital Village case study in the Fixed Wireless Access Handbook  that have been adapted to US data consumption patterns.
The original case study includes a step-by-step solution and business case analysis showing a ROI of 22 months. Here, we focus on comparing achievable network capacity, with and without mmWave. The target case is a village with sparsely populated surroundings with a total density of houses around 150 homes per square kilometer. Existing broadband bandwidths are mainly provided by best-effort xDSL or MBB, but there is no fiber to the home, making the area an attractive candidate for an FWA system.
The current MBB deployment has a total site spacing of 3 km, and the lower FDD bands are used to serve the existing traffic. Over time, as MBB traffic grows, you will use a portion of the acquired mid-band spectrum. Excess spectrum can be used for FWA: 100MHz TDD at 3.5GHz and 400MHz in the 28GHz band.
The service targeted by the CSP is FWA with a “fiber-like” experience. This means that DL data rates sold are 100-1000+Mbps with no data cap and typical DL rates of at least 100Mbps. By combining the available spectrum, including the low FDD, mid and 28 GHz bands using TDD, CSP can obtain a common network deployment that caters to both MBB and FWA.
In this analysis, we focus on the mid-range and at 28GHz, leaving the details on the lower bands as well as performance for MBB users. However, the proposed approach includes a combined FWA and MBB solution that also addresses the expected growth of MBB traffic. Furthermore, since the state is limited by the amplitude of the DL, we ignore the UL analysis. To maximize link performance, the enclosure relies on the use of surface-placed, high-power mmWave-enabled CPE as well as lower bands.
The system is designed to target a minimum DL data rate of 30 Mbps for the worst 5 percent of homes, at peak hours, to maintain a fiber-like experience, including multiple HDTV streams per home, also in those worst cases. In terms of data usage, we define a baseline scenario, based on current fixed broadband levels observed in the United States, where average data consumption per home is expected to be 670 GB per month, of which 90 percent (600 GB) is DL traffic. [10, 11].
Assuming that 10 percent of daily traffic occurs during the busiest hours, this corresponds to an average consumption of 2 gigabytes per hour in the busiest hour. We assume 28 percent annual growth, driven in part by many homes switching from consuming linear TV over satellite or terrestrial broadcasting, to using broadband for all media consumption including linear TV and streaming services.
Additionally, for comparison, we also defined a broadband media scenario that assumes that all homes have already made this transition. In this case, we’re assuming a consumption rate of 1 TB per month per home (900 GB per month in DL) but expect 10 percent lower annual growth, as the shift to all media consumption over broadband has already been completed.
Since capacity needs to grow as the number of customers increases, as well as as average data consumption and speed requirements rise, it makes sense to gradually increase network capabilities based on needs. This means that the costs of increasing capacity can be taken as late as possible, unlike fiber, where a large portion of the cost is taken up front when deploying fiber trunks that pass through all homes. Moreover, decisions about capacity enhancement can be made selectively on a sector-by-sector basis as the number of subscribers – and revenue – increases.
Experienced user data rate
Figure 3 Shows the data rate of an experienced DL user as a function of system load change for worst, medium, and best site homes, respectively. The blue curves represent only the mid-range spread, and the red curves represent the combined mid-range and mmWave can.