Navigating the Complexities of Wi-Fi Installations
Author: Henry Martel, field application engineer, Antaira Technologies.
Wireless installations are often seen as an easy replacement for cables, particularly in situations where running wires or fiber optics is impractical or too costly. While wireless solutions can be convenient, even the simplest application of a wireless networking standard can come with challenges that need careful planning and troubleshooting. This article provides insight into the planning and deployment of a successful wireless installation.
Site Survey and Spectrum Analysis
Before beginning any wireless installation, conducting a thorough site survey and spectrum analysis is essential. A site survey allows installers to measure actual signal strength, identify dead spots, and detect sources of interference throughout the area. Spectrum analysis can reveal existing wireless networks and other sources of radio frequency (RF) noise that may compete for bandwidth. By understanding these environmental factors, installers can plan more effectively, especially in congested areas where multiple networks may already be operating. This preemptive approach helps prevent performance issues and ensures a more reliable setup from the start.
Overcoming Environmental Challenges
Wireless networks are particularly appealing in industrial settings, where it’s challenging to run cables, whether twisted pair or fiber optic, through complex environments. Take a machine shop as an example, where a wireless network was used to install a surveillance system. Over the weekend, the wireless network itself was installed and tested, and everything seemed to be working perfectly. But on Monday morning, when the shop workers arrived and began operating machinery, the whole wireless access network stopped working. What happened?
Before jumping to solutions, it's essential to consider potential troubleshooting methods. For instance, checking for interference sources like high-power motors, testing network stability at different times, and measuring wireless signal strength around machinery could help identify the problem. In this case, it’s likely that many of the machines in the shop use high-power electrical motors, which often emit electromagnetic interference (EMI) or RF noise. This RF noise can disrupt Wi-Fi signals by creating interference within the wireless frequency range, especially if the equipment is unshielded.
To address this, you could use directional antennas to focus the signal and power through the interference. Alternatively, try guiding the signal around problematic areas with known sources of RF noise. In some cases, shielding certain motors or repositioning equipment may also be options.
Line of Sight: More Than Meets the Eye
"Line of sight" is a common term used when deciding if a wireless connection is feasible. However, it’s one of the most misunderstood terms in wireless installations. A clear visual path between two points doesn’t necessarily guarantee a stable wireless connection. For example, if you’re setting a up wireless access point or a wireless bridge to connect wireless devices between two buildings and can see the far building from the near one, you might assume line of sight is established, and the wireless access point connection can be made. However, this may not always be the case.
This is where the Fresnel zone concept becomes important. The Fresnel zone is a football-shaped area between two antennas, and any obstruction within this zone can cause interference. The frequency in use (2.4 GHz, 5 GHz, 6 GHz, 60 GHz) affects the size and shape of the Fresnel zone, but the general concept remains the same: the clearer this zone is, the less signal interference and stronger the signal. This is one reason why placing antennas higher up can improve signal quality—the lower half of the Fresnel zone avoids being obstructed by the ground.
It’s also important to remember that line-of-sight conditions can change over time. For instance, trees may lose their leaves in fall but fill out in summer, potentially blocking signals. New structures or other objects might be placed in the path that was once clear. Asking about future plans and assessing the likelihood of seasonal changes can prevent unexpected disruptions.
Echoes and Reflections
In industrial environments, certain building materials can interfere with wireless signals. For instance, many industrial buildings use corrugated steel siding for cost efficiency and durability. Unfortunately for wireless security, this material can cause a reflective, echoing effect which confuses the wireless receivers.
This problem often occurs when an antenna, especially an omnidirectional one, is mounted flat against corrugated steel. The effect is somewhat more obvious with omnidirectional antennas, but even directional antennas like panel antennas can experience similar issues. Panel antennas have multiple radiation patterns called "lobes". The main lobe points in the direction of the desired connection. However, side lobes can bounce back when mounted against steel, creating interference. Mounting the antenna a few feet away from the wall can often mitigate this issue.
Metal walls aren’t always as obvious as corrugated steel; sometimes, metal mesh inside walls or even certain types of insulation can cause issues. Asking about wall materials can provide helpful insight before installation begins.
Latency Requirements
When implementing wireless networks for latency-sensitive applications—such as real-time monitoring or automated machinery—it's crucial to consider potential challenges. Wireless signals can experience latency and jitter due to interference, signal reflection, and congestion, impacting performance. However, advancements in Wi-Fi technology, particularly Wi-Fi 6 and Wi-Fi 7, have introduced features designed to address these issues. Wi-Fi 6 incorporates Orthogonal Frequency-Division Multiple Access (OFDMA) and Target Wake Time (TWT), which enhance network efficiency and reduce latency by allowing more devices to communicate simultaneously and scheduling transmissions to minimize contention.
Wired connections are generally preferred for applications requiring the highest reliability and lowest latency. If a wireless setup is essential, it should be carefully evaluated to ensure it meets the performance requirements of these demanding applications.
Planning for Coexisting Networks
Before installing a new wireless network or connecting devices, assess the environment thoroughly to understand existing wireless setups and potential sources of interference. This is especially important when using the 2.4 GHz band, as only three non-overlapping channels are available. While adding a new 2.4 GHz link might still be possible, switching to a 5 GHz or 60 GHz frequency is often advisable if other devices' open networks or data traffic may already occupy this band.
Another important consideration is the presence of other wireless signals that may overlap or jam the frequencies of mobile devices you plan on using. High-density areas are more prone to frequency congestion, while remote areas are typically less impacted by interference.
Avoiding Common Pitfalls in Wireless Installations
Wireless applications, though often perceived as straightforward, come with unique challenges. Knowing what to look for during the design phase can help avoid issues during the installation and operation of connected devices. By carefully planning and understanding potential obstacles, installers can avoid common pitfalls, ensuring a more reliable Wi-Fi security setup.
Reach out to Antaira at (714) 671-9000 to discuss your Wi-Fi networks and see how our Wi-Fi devices (wireless routers, wireless access points, and Wi-Fi client devices) can help give you Wi-Fi protected access to any application.
About the author: Henry Martel is a field application engineer with Antaira Technologies. He has more than 10 years of IT experience along with skills in system administration, network administration, telecommunications, and infrastructure management. He has also been a part of management teams that oversaw the installation of new technologies on public works projects, hospitals, and major retail chains.
www.antaira.com
