Extending Wi-Fi Connectivity Over 50 Kilometers

Quick Summary

Radio engineers are repurposing standard Wi-Fi protocols to create wireless bridges capable of spanning distances up to 50 kilometers. Originally designed for short-range connectivity within homes or offices, the 802.11 standard is being pushed beyond its intended scope to connect remote locations without physical cables.

This technical approach requires overcoming significant physical challenges, including managing the first Fresnel zone, accounting for the Earth's curvature, and adjusting acknowledgment settings. The article explores the technical nuances of establishing these long-distance links, including the importance of clear line-of-sight and the impact of environmental obstacles like trees.

Additionally, it touches upon regulatory concerns, noting that such long-range wireless operations have drawn scrutiny from authorities like Roskomnadzor, similar to how growing trees can obstruct signals. The discussion highlights the gap between the original intent of wireless protocols and their current, more ambitious applications.

Repurposing Wireless Protocols

The Wi-Fi protocol was originally created to connect laptops and PDAs within the confines of a home or office. The expectation was that traffic through an access point would be initiated by human activity. With the rise of the Internet of Things (IoT), smart kettles, refrigerators, and meters joined laptops on the network, but the core concept remained unchanged: the access point gathers consumers within its immediate or adjacent rooms.

However, this limitation proved insufficient for some applications. A concept emerged to extend the wireless link beyond a neighboring room to a garage under a window, or even to a neighboring settlement. It was discovered that this was indeed possible through the use of a radio bridge. This technique allows for a 50 km link in a single span using standard 802.11 technology without wires.

Technical Challenges of Long-Range Links

Establishing a stable 50-kilometer wireless connection involves addressing several specific technical nuances. The physics of radio wave propagation requires careful management of the signal path to ensure data integrity over such distances.

Key technical considerations include:

• The importance of the first Fresnel zone, which must remain largely unobstructed.
• The need to potentially disable ACK (acknowledgment) mechanisms to optimize throughput.
• Accounting for the radius of the Earth's curvature when calculating line-of-sight.

These factors dictate the placement of equipment and the specific configurations required to maintain a viable connection.

Regulatory and Environmental Obstacles

Aside from technical hurdles, long-distance Wi-Fi bridges face external pressures. The article notes that Roskomnadzor poses a significant threat to these operations, comparable to the interference caused by growing trees in a forest. This suggests that regulatory compliance and signal clearance are critical for maintaining these links.

Environmental factors, such as vegetation growth, can physically block the necessary line-of-sight, while regulatory bodies may restrict the use of the spectrum or the operation of such high-power, long-range transmissions. Both elements present significant challenges to the viability of radio bridges.

Conclusion

Pushing Wi-Fi to cover 50 kilometers demonstrates the adaptability of standard wireless protocols beyond their original design parameters. While technically feasible, achieving such links requires deep knowledge of radio physics, including Fresnel zones and terrain curvature.

However, the success of these projects depends not only on technical execution but also on navigating environmental obstructions and regulatory oversight. As the demand for wireless connectivity grows, the tension between technical innovation and regulatory frameworks will likely continue to shape the future of long-distance networking.