Airport Safety: 24 Ghz Interference And Its Impact

The use of wireless communication has become integral to airport operations and, as a result, reliable and high-performance WiFi is critical for modern airports. However, wireless communication is subject to radio frequency (RF) interference, which can cause significant disruptions.

One source of interference is the 2.4 GHz frequency band, which is often congested due to the large number of devices that operate within this band, such as microwave ovens, Bluetooth devices, and lights. This congestion can lead to slower data rates, higher transmission errors, and increased packet retransmissions, affecting the performance of airport WiFi networks.

To mitigate these issues, airports can consider alternative wireless technologies, such as Distributed Antenna Systems (DAS) or Wi-Fi 6, which offer higher capacity and better performance. Additionally, private cellular networks that utilize different frequency bands can be deployed for airport operations and safety, ensuring reliable and secure communications.

While 24 GHz interference may not be the sole cause of issues at airports, it is a contributing factor that needs to be addressed to ensure smooth and efficient airport operations.

Wi-Fi interference with airport operations

Wi-Fi interference is a common issue at airports, and it can cause significant disruptions to airport operations and passenger experiences. The increasing use of wireless technology, such as Wi-Fi, has become integral to airport operations, and its reliability and performance are critical.

The 2.4 GHz band is often congested due to the majority of Wi-Fi traffic and the limited number of non-overlapping channels available. This congestion can lead to slower data rates, higher transmission errors, and packet retransmissions, affecting the overall performance of the Wi-Fi network. Additionally, the placement of Wi-Fi access points and the architectural design of the airport can impact signal quality and network coverage.

To mitigate Wi-Fi interference, airports can implement various strategies:

• Use of the 5GHz band: The 5GHz band is less congested and offers higher data rates. Airports can encourage the use of this band by providing separate network names for the 2.4GHz and 5GHz bands, allowing devices to connect to the higher band when possible.
• Channel distribution: Evenly distributing Wi-Fi traffic across available channels and ensuring that neighbouring access points use different channels can reduce interference.
• Dynamic Frequency Selection (DFS): DFS allows Wi-Fi systems to detect and avoid interference from other radar systems using the same frequencies.
• Transmit Power Control: This technique adapts the transmission power to minimise interference while maintaining effective communication.
• Active network testing and monitoring: Regular testing and monitoring can help identify and resolve issues before they cause major disruptions.
• Clear Channel Assessment (CCA): CCA helps Wi-Fi devices determine if a transmit channel is available before transmitting data, reducing potential interference.
• HotSpot 2.0: This technology enables automatic connections for users, reducing the load on the network and improving performance.
• Distributed Antenna Systems (DAS): DAS uses multiple antennas to reduce the power transmitted over a given area, minimising interference and improving reliability.

By employing these strategies, airports can enhance the performance and reliability of their Wi-Fi networks, ensuring seamless operations and a positive experience for travellers.

5G interference with airport operations

5G interference has been a concern for airport operations, particularly regarding radio altimeters, which are important safety equipment in aircraft. Radio altimeters provide highly accurate information about an aircraft's height above the ground, and data from these altimeters informs other safety equipment such as navigation instruments, terrain awareness, and collision-avoidance systems.

In the United States, 5G services were launched in 46 markets on January 19, 2022, using frequencies in a radio spectrum called the C-band. These frequencies are close to those used by radio altimeters, which raised concerns about potential hazardous interference. To address this, the Federal Aviation Administration (FAA) imposed restrictions on flight operations using certain types of radio altimeter equipment close to antennas in 5G networks.

The FAA worked with wireless companies and the aviation industry to find solutions and ensure the safe coexistence of 5G and aviation. This included voluntary mitigations by telecommunication operators and retrofitting of aircraft radio altimeters by aviation operators. The FAA also identified airports where 5G service could be enhanced with minimal risk of disrupting flight schedules. During the initial negotiations, wireless companies offered to maintain mitigations until July 5, 2022, to understand the effects of 5G C-band signals on sensitive aviation instruments better.

The FAA issued several Airworthiness Directives (AD) to provide a framework and gather information to avoid potential effects on aviation safety equipment. These ADs revised landing requirements for certain aircraft models at airports where 5G interference could occur. The directives prohibited landings in low-visibility conditions without upgraded altimeters and applied to specific Boeing aircraft models, including the 737, 747, 757, 767, and 777.

The FAA's efforts, in collaboration with the wireless and aviation industries, were successful in mitigating the risk of 5G interference. By the end of September 2023, the entire U.S. airline fleet had upgraded their equipment, and the risk of 5G interference was minimized. The FAA continues to work with both industries to track the pace of radio altimeter retrofits and relax mitigations around key airports.

To provide live information to operators, the FAA launched an interactive map that covers 87 airports where 5G network transmitter deployment may affect landings in instrument meteorological conditions. This map allows users to check if low-visibility landings are permitted at specific airports, runways, and aircraft types, considering potential 5G interference on radar altimeters.

The FAA's collaboration with the wireless and aviation industries has been crucial in ensuring the safe coexistence of 5G and aviation operations. Through voluntary agreements, retrofitting of equipment, and ongoing monitoring, the impact of 5G interference on airport operations has been effectively managed.

Radar interference with Wi-Fi

Wi-Fi operates in the 2.4GHz and 5GHz bands, which are unlicensed spectrums that vary by country. The 5GHz band is preferred as it generally has less interference from outside sources. However, radar systems in some countries use frequencies that inhabit the 5GHz Wi-Fi channels, leading to potential interference issues.

To mitigate this, the Wi-Fi standard (IEEE 802.11) incorporates a spectrum-sharing mechanism called Dynamic Frequency Selection (DFS). DFS detects when a radar facility is nearby and ensures that Wi-Fi devices do not interfere with radar operations. When radar is detected, Wi-Fi devices must cease transmissions on that channel within 10 seconds and move to a new, non-conflicting channel.

While DFS helps prevent Wi-Fi interference with radar, it can cause temporary disruptions in Wi-Fi connectivity, particularly for Wi-Fi phones, as devices may need to re-authenticate on a new channel. Additionally, if many devices are moved to the same non-conflicting channel simultaneously, there is a risk of congestion, which can also lead to poor network performance.

To minimise the impact of DFS events, network administrators can exclude impacted channels from channel planning, use non-DFS channels if available, or work with vendors to identify and address local sources of interference.

Bluetooth interference with Wi-Fi

Bluetooth devices and Wi-Fi routers use similar radio frequencies, and when too many devices are sharing the same frequency, it can cause connection problems and bandwidth issues. This can result in a slow internet connection or even cause it to cut out.

To reduce Bluetooth and Wi-Fi interference, you can try the following:

• Move Bluetooth devices away from building materials such as metal, concrete, plaster, and brick that can act as barriers.
• Avoid placing Bluetooth devices near microwaves or fluorescent lights, as they use the same frequency.
• Move devices closer to the router, as altering the device's placement can improve the strength of the Wi-Fi connection.
• Reboot the router and try a different channel. Depending on the router, channel surfing may occur automatically or manual selection may be required.
• Change the router from the 2.4GHz band to the 5GHz band.
• Change the Wi-Fi router settings to only use 20MHz-wide channels, as 40MHz-wide channels in 2.4GHz don't leave enough room for other users of the band, such as Bluetooth.
• Purchase a dedicated Bluetooth adapter.
• Ensure that the Bluetooth driver is up to date.
• Use a tool like inSSIDer to see what Wi-Fi channels are in use and pick the least busy option.
• If possible, ask your neighbours to set their network to 20MHz-only if they are using 40MHz-wide channels.

Microwave interference with Wi-Fi

Microwaves and Wi-Fi routers both use electromagnetic waves to function, and when these waves clash, it can cause issues with your Wi-Fi connection. Microwaves emit electromagnetic radiation at a frequency of 2.4 GHz, which is the same frequency that Wi-Fi devices use to transmit data. This means that when a microwave is in use, the electromagnetic waves can interfere with Wi-Fi signals, hindering your Wi-Fi connectivity and causing problems such as slow web-loading speeds and interrupted video transmission.

The Impact of Microwave Interference

The impact of microwave interference on Wi-Fi can vary depending on several factors, including the distance between the microwave and the router, the power of the microwave, and the quality of shielding in the microwave. In some cases, using a microwave near a Wi-Fi router can cause frequent high spikes in latency, packet loss, and even complete drops in the Wi-Fi connection. This can result in slow internet speeds, buffering or crashing of streaming services, and lag or crashes of online games.

Reducing Microwave Interference

There are several ways to reduce the impact of microwave interference on Wi-Fi:

• Move the Router: Moving the router away from the microwave can help to reduce the impact of interference. Placing the router in a different room or at least several feet away from the microwave can improve the Wi-Fi signal.
• Use a Dual-Band Router: Upgrading to a dual-band router that supports both 2.4GHz and 5GHz frequencies can help to reduce interference. Devices that support 5GHz should be placed on this band, while older devices can continue to use 2.4GHz.
• Replace the Microwave: If the microwave is faulty or inadequately shielded, it may leak excessive electromagnetic radiation, causing more interference than normal. Replacing the microwave with a heavier-built or better-shielded model can help reduce interference.
• Use Ethernet Connections: For devices that support it, using Ethernet cables to connect directly to the router can eliminate Wi-Fi interference issues.
• Change Wi-Fi Channel: Wi-Fi routers typically have multiple channels available in the 2.4GHz band. Changing the channel can help to reduce interference, as some channels may be further away from the frequency of the microwave.
• Use a Faraday Cage: Placing the microwave inside a Faraday cage can help to contain the electromagnetic radiation and reduce leakage, minimizing interference with Wi-Fi signals.

While microwave interference can be frustrating, it is not dangerous. We are constantly surrounded by various forms of electromagnetic radiation from sources such as phones, baby monitors, and appliances. The small amount of radiation that leaks from a microwave is not harmful to your health or your electronic devices.

Frequently asked questions