A new method to study possible fiber routes

To realize our vision of the metaverse, we will need to reinvent a network infrastructure capable of supporting the computing platforms of the future. Although the metaverse is still a long way off, elements of it are already underway, and we are already collaborating with telecommunications companies around the world to develop open access and shared fiber optic networks that can help support this work. By sharing costs and making network capacity available to all market ecosystems, open networks help make abundant, affordable, high-quality Internet accessible to more people today – and ultimately, to fulfill the promise of the metaverse.

When we started thinking about investigating potential fiber routes through the Democratic Republic of Congo (DRC), we knew that paved roads (essential for laying these fiber optic cables) were scarce, which meant that we would need a different approach to gathering a rich set of data to inform our construction cost estimates. In collaboration with Sofrecom and its partners CVA groupand SOTEK Groupwe implemented a new technique for surveying fiber optic routes, which exploits dynamic cone penetrometers (DCP) and gamma-ray spectrometers to speed up the survey process and improve the accuracy of cost estimates for the network building, allowing companies to quickly determine if a new project is feasible.

The route engineering process

For most Meta Fiber projects, we work with telecom industry partners to plan and deploy networks. The process starts by identifying the sites that Meta and our partners want to connect, then we use OpenStreetMap (OSM) data with our network planning tools to iterate over route options and select an optimal mid-level design (i.e. which route). After further refining the designs in collaboration with project partners, we move on to the final step: completing a low-level design (i.e. which side of the road) using various survey techniques on the ground to collect data on potential barriers to construction.

The stages of designing a new fiber route

As part of the process, we also seek to determine the amount of materials required for a project as well as the preferred construction methods. With this data in hand, we can then estimate both the time and cost to deploy a fiber network, both of which are key elements in assessing the financial viability of any project.

Innovation Opportunity

One way to improve the accuracy of cost estimates for underground fiber networks is to classify ground conditions. This is important because the volume of soil to be excavated is a major cost factor and the density of the soil is another: the harder the soil, the more effort it takes and the higher the cost.

A common method for collecting soil density data is to use a dynamic cone penetrometer (DCP). This device estimates soil density (measured in megapascals) by correlating the force required to drive a steel rod into the ground with the depth of rod achieved by that force. By repeatedly striking the rod to the desired depth (eg two meters), a soil density profile from the surface to the final depth can be calculated. A DCP is a relatively inexpensive and easy to use instrument, but it is not a quick process. Plus, its measurements are very localized, so to really add value, you have to do a lot of testing – easily dozens per kilometer – adding significant time and cost to an investigation.

Another method of estimating soil density is to collect data with a gamma ray spectrometer. This device is quite common in the mining industry and takes advantage of the fact that traces of radioactive elements exist in many minerals. A spectrometer can detect and measure gamma radiation emissions from elements such as uranium, thorium and potassium. This data can be analyzed and used to estimate soil density because the radiation source and radiation levels depend on soil composition and soil particle size. Although more expensive and more complex than a DCP, data collection with a spectrometer is highly automated and a person can be quickly trained to collect data for remote post-processing and analysis by specialist geologists.

Another strength of a spectrometer is its ability to detect soil heterogeneity. It can identify where changes in subsoil conditions are occurring. If the emissions are similar in an area, it is relatively safe to conclude that the soil is homogeneous throughout the area. This is important because spectrometer results require calibration against control data. In our case, control data is collected via DCP.

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Inspiration

Roads are essential for the rapid and cost-effective development of fiber optic networks. Burying fiber optic cables along roads makes it easy to move the materials, equipment, and labor needed to install a network. The routes also simplify future operations, as network technicians must return to monitor and maintain the fiber over its 20+ year lifespan.

However, roads (and bridges) are expensive to build and maintain. This is particularly true in some countries like the DRC. With a vast 2.3 million km2 geography (much of which is covered in rainforest and criss-crossed by rivers and streams) and an annual GDP per capita of around $1,000, the DRC has been able to develop just 3,000 km of paved roads (similar to the Luxembourg, a country whose size is 0.1% of the DRC). This means that the logistics of fiber projects in the DRC are complicated and expensive.

So when we started thinking about investigating potential fiber routes through the DRC, we knew that a different approach might be needed to collect a rich data set that could better inform our construction cost estimates. We went looking for an innovative and disruptive route study technique and found it in a solution offered by Sofrecom and its partners Groupe CVA and SOTEK Group.

Using a DCP in conjunction with a spectrometer mounted on a high-clearance 4×4 vehicle, we created a high-speed soil density classification process:

  • First, a SOTEK team operating a spectrometer collected the gamma emissions, then transmitted the data to CVA in France for post-processing (the spectrometer data was combined with geological data from other sources) and expert analysis.
  • Preliminary results were sent back to the field with specific locations for a second SOTEK team to collect the DCP measurements, which were then handed over to CVA to finalize the soil density analysis.

This way, the number of DCP tests for the survey was minimized with a relatively small collection of DCP test results used to calibrate a large amount of spectrometer data. Alongside the DCP measurements, an application running on a mobile device with GPS was used to capture traditional survey data points such as construction obstacles, as well as ecologically and culturally sensitive areas. Through this process, we were able to create a detailed GIS map combining typical survey data with detailed ground condition information, all without extending the survey timeline.

One of the limitations of a spectrometer is that it cannot be used to capture data under paved surfaces, as the materials of asphalt and concrete include some of the same radioactive elements found in soils, so that all results would be highly skewed. However, with so few paved roads in the DRC, we were able to turn the road conditions to our advantage.

DRC map.  The orange lines show our fiber survey routes.
DRC map. The orange lines show our fiber survey routes.

Cost risk management

Economics is often a barrier to connectivity, even more so in emerging markets, where project costs are often similar to those in developed markets. Moreover, short-term returns are often reduced compared to developed markets, due to factors such as low internet penetration and low income. We hope that methods such as the ones described above will reduce project risk worldwide through reliable field data, helping more projects overcome the initial hurdles of their business case and removing some of the unknowns. .

And after?

Using this technique, we have completed the survey of over 5,000 km of potential fiber routes across the DRC, but there is room for improvement in this method. Other technologies such as hyperspectral imaging and ground penetrating radar also show promise as data collection techniques. Of course, we are leaders in computer vision and machine learning, areas that are very useful for dealing with this type of investigation. Our capabilities in these areas can be applied to these types of datasets to help future route investigations by:

  • further reduce costs;
  • increased process speed;
  • increase fidelity and accuracy; and
  • enabling in-country partners to do more of this technical work locally and helping them develop their national telecommunications ecosystems in the process.

Over the past decade, we have invested billions of dollars alongside partners in the telecommunications industry to improve connectivity around the world. These open and collaborative efforts include internet exchanges and carrier-neutral colocation to extend the benefits of our fundamental investments in infrastructure such as fiber optic and submarine cables. Through these open and collaborative efforts, we’ve seen firsthand how industry-wide collaboration can improve and expand global connectivity. As we help lay the foundation for the metaverse, we will continue to pilot projects that will help equip people around the world to thrive in this bold future.

We would like to thank Ibrahima Ba, Fabrice Ouandji and Clive Van Hilten for their work on this project.

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