With Advancements in Technical Capabilities, Is Free-Space Optics Communications Finally Able to Overcome Past Failures?

In August 2024, T-Mobile partnered with Transcelestial, a technological startup company from Singapore, to deploy the latter’s Free Space Optics (FSO) wireless connectivity solution at the 2024 Coachella and Stagecoach music festivals. The companies claim that the deployment of FSO technology helped them achieve peak speeds over 7.5X higher than their competitors, thus providing enhanced user experiences for customers of the Communication Service Provider (CSP). Despite facing adverse weather conditions—including wind speeds of up to 93 Kilometers (km) per hour—the FSO links were reportedly able to continue providing reliable connectivity, thereby successfully overcoming one of the key issues (i.e., tower sway) that previous FSO solutions have generally not been able to tackle.

With FSO solutions typically boasting lower Total Cost of Ownership (TCO) compared to their microwave and fiber counterparts, there appears to be renewed interest in the technology. Transcelestial is one such example. Founded in 2016, the company’s laser communication solution is gaining interest in the industry, with Transcelestial raising US$24 million, to date, from major investors such as Airbus Ventures, EDBI, Wavemaker Partners, etc. The company is also actively selling its solution across multiple regions, including but not limited to Asia-Pacific, North America, and South America.

In the past, FSO was initially regarded as a strong candidate for wireless backhaul applications. This was mainly due to the benefits that FSO solutions had over other backhaul alternatives, including but not limited to:

• Spectrum Availability and Fees: Operating in the 200 Terahertz (THz) spectrum band, there are large amounts of available spectrum to scale up data throughput rates according to network requirements. Additionally, spectrum in the 200 THz range is generally unregulated, thereby helping CSPs save on spectrum costs as opposed to microwave deployments.
• High Throughputs: With significant bandwidth available, FSO solutions can support data throughputs of 10 Gigabytes per Second (Gbps) or higher. For example, Transcelestial claims that its CENTAURI 25G solution can support up to 25 Gbps, thereby helping CSPs meet the increasing demand for data speeds.
• Low Total Cost of Ownership (TCO): As mentioned, FSO solutions offer cost savings over fiber deployments due to reduced complexity of deployments. The low energy consumption of FSO equipment also positions the technology as a strong competitor for microwave solutions.
• High Security: The narrow beams—due to the high frequency lasers used—offer enhanced link security against data interception and Man-in-the-Middle (MITM) attacks.

However, the adoption of FSO among CSPs has remained low, as it has been unable to support carrier-grade availabilities (i.e., 99.999%) and long-range links. This was due to the FSO solution’s susceptibility to weather conditions (e.g., wind, rain, mist, dust, etc.), where direct line-of-sight was needed to maintain a consistent wireless connection between FSO equipment. However, new developments in FSO technology, such as the use of Artificial Intelligence (AI)-based tracking and hybrid FSO-microwave deployment architectures, are seeking to address the aforementioned challenges.

Despite the advantages that FSO solutions can bring, there remain challenges hindering large-scale adoption of the technology. Recent reports indicate that Indian CSP, Bharti Airtel, is still hesitant on commercially deploying Google’s Taara FSO solution due to concerns about link availability, especially during times of adverse weather conditions.

Hence, ABI Research recommends that FSO equipment vendors need to consider the following to demonstrate the value that FSO solutions can bring to CSPs:

• Weather Predictability: FSO solutions perform best in stable and predictable weather environments. FSO vendors should work closely with CSPs to identify locations that best meet these conditions to deploy FSO connectivity successfully.
• Flexible Scaling of Networks: As illustrated by the case example of T-Mobile, FSO solutions are well suited to support flexible network scaling to meet the network requirements for high data traffic events. The low TCO and ease of installation of FSO solutions provide CSPs with a quick and low-cost deployment option for mobile backhaul in these and/or other emergency scenarios.
• Hybrid FSO-Microwave Deployments: Hybrid FSO-microwave deployments enable CSPs to take advantage of the high data throughputs afforded by FSO solutions, while also allowing for fallback to microwave links in adverse weather conditions to maintain consistent link availability. This could be a viable option for FSO vendors to consider offering, especially in areas where weather fluctuations occur frequently.

While there are existing challenges, with rapid advancements in AI and Machine Learning (ML) capabilities—and also taking reference from microwave technology developments—ABI Research is optimistic that new AI/ML solutions will emerge in the near future to help FSO solutions adapt to different weather conditions and establish the technology as a reliable option for backhaul connectivity.