Lidar and Broadband: How the 3D Elevation Program Helps Map Internet Access

A simulated viewshed from a transmitter on a Chicago rooftop, built from lidar; blue marks what the transmitter can see. U.S. Geological Survey.

The gap

Broadband — a fast, always-on internet connection — is essential to the economy and education, and to health care, public safety, government services and entertainment. Yet according to the Federal Communications Commission, millions of Americans in rural areas lack it, and federal and state agencies have launched efforts to reach them.

High-resolution lidar (light detection and ranging) can help. It underpins signal propagation studies — where a tower's signal can and can't reach — and helps choose the best sites for new towers and cell stations.

How lidar helps

The 3D Elevation Program (3DEP), managed by the U.S. Geological Survey with federal, state, tribal, territorial and local partners, is gathering consistent lidar for the whole country: precise 3D pictures of natural and built features.

• Viewshed (line-of-sight) analysis uses lidar's bare-earth and surface models to work out what is visible from a point — such as the top of a tower.
• Clutter — the industry's word for buildings, hills and other features — weakens or blocks signals and shrinks a transmitter's coverage.

A lidar point cloud in Olympia, Washington: trees, buildings and other objects that can weaken or block a signal. Color shows elevation. USGS / Cindy Thatcher.

Rural networks and 5G

Rural broadband would open the door to internet uses that the economy and schools increasingly depend on.

• 5G networks will serve not only phones and computers but medical equipment, security cameras, traffic signals, manufacturing and delivery robots — the "Internet of Things."
• Precision agriculture needs a signal in every corner of a field to run advanced equipment.
• 5G's faster high-band spectrum travels shorter distances and is more easily blocked by clutter.
• Lidar can measure the height of silos — often a farm's highest point, and a place for antennas — and a viewshed can show where their signal reaches. Such work could feed the mapping of structures that need service, the "fabric of broadband serviceable structures."

Mapping coverage

• Cambium Networks, a wireless connectivity company offering cloud-managed Wi-Fi and fixed wireless broadband, uses 3DEP lidar where available to model signal propagation and predict radio-frequency coverage more accurately. Installers can go straight to the spot with the best connection and skip places where service isn't possible.
• The National Telecommunications and Information Administration publishes indicators of broadband need, including the share of households in each census tract with no internet access.

Households with no internet access, by census tract. NTIA data from the Census Bureau's American Community Survey; map by the U.S. Geological Survey.

Lidar could feed models of signal propagation from existing towers and make coverage maps more detailed and accurate — better data for decisions on broadband policy and investment, and for closing the digital divide between rural and urban America.

About 3DEP

3DEP's goal is nationwide lidar — IfSAR radar in Alaska — for the first-ever national baseline of consistent, high-resolution elevation data: bare-earth elevation models and 3D point clouds.

• Benefits: economies of scale; predictable, flexible federal funding that lowers costs; consistent coverage across project, jurisdiction and watershed boundaries; simpler buying, with contracts, management, quality checks and specifications handled; and national benefits of $690 million a year, conservatively, with the potential for $13 billion a year more across the economy.
• Quality: at least two points per square meter, vertical error no more than 10 centimeters (root mean square), and a 1-meter bare-earth model. Data go into The National Map, free and without use restrictions — download here.
• Joining in: open to federal, state, tribal, territorial and local governments and private partners, who can buy higher-quality data. Partners can fund USGS-run projects or get cooperative funds to run their own, through a yearly Broad Agency Announcement; data that meet 3DEP's standards can be contributed. See usgs.gov/3DEP.

Sources

Based on 3D Elevation Program Supports Broadband Internet Access, U.S. Geological Survey Fact Sheet 2021–3056, by Cindy A. Thatcher and Vicki Lukas, USGS Publications Warehouse; a work of the United States government in the public domain. The benefit figures come from Dewberry's National Enhanced Elevation Assessment (2012). Figures recovered from the fact sheet's PDF; a screenshot of Cambium Networks' coverage model is not reproduced.