Certified - CompTIA Network +

Wireless networks offer tremendous flexibility and convenience, but they also introduce performance constraints that are often misunderstood or misdiagnosed. Unlike wired networks, where speed and reliability are largely determined by cable quality and switch configuration, wireless communication depends on radio frequency behavior. Environmental variables, client device capabilities, and interference from nearby equipment all play a role in limiting performance. Many wireless complaints—such as slow speeds, dropped connections, or inconsistent coverage—stem from physical constraints and signal limitations rather than misconfigured settings. That’s why understanding wireless limitations is essential for both troubleshooting and proactive design.
In this episode, we focus on the three primary constraints that affect wireless network performance: throughput, signal strength, and power. These factors interact in complex ways, and failure to understand their relationship leads to ineffective solutions. We’ll examine how throughput differs from advertised speed, how signal strength is measured and interpreted, and how power mismatches between access points and clients can result in connection failures. For those preparing for the Network Plus exam, this episode will also reinforce key wireless concepts that frequently appear in scenario-based questions.
The first limitation to understand is the difference between wireless throughput and the theoretical speed listed in device specifications. A wireless router or access point might advertise speeds of 300 Mbps or even 1 Gbps, but actual usable throughput will be significantly lower. This is due to protocol overhead, including encryption, management frames, and retransmissions. Wireless is a shared medium, so only one device can transmit at a time on a given frequency, and all others must wait their turn. This contention, along with collisions and retries, further reduces efficiency. The higher the client density, the more severe the throughput drop.
Low throughput can result from several overlapping conditions. One major cause is high client density—too many devices competing for access on the same channel. Another is channel congestion, where multiple access points in the same area use the same or overlapping channels. Signal degradation due to weak signal strength, interference, or distance also reduces throughput by forcing devices to use lower modulation schemes. The end result is sluggish performance, even if the signal bars on a device appear strong. Throughput must always be measured in context—not just as a function of speed, but as the ability to transmit clean, uninterrupted data under real conditions.
Signal strength is another key factor in wireless performance and is typically measured in dBm—decibels relative to one milliwatt. These values are negative, and the closer the value is to zero, the stronger the signal. A signal of -30 dBm is excellent, indicating a close and clean connection. A signal of -67 dBm is considered the minimum for reliable VoIP and real-time applications. Once signal strength drops below -80 dBm, connectivity becomes unreliable, and packet loss is common. Devices may disconnect entirely, or connections may persist but with severely reduced speeds. Interpreting these values helps technicians determine whether a problem lies in coverage or client-side limitations.
Signal-to-noise ratio (SNR) is closely related to signal strength but focuses on the difference between the wireless signal and the background noise on the same frequency. A high SNR means the signal is strong and the noise is low, resulting in reliable communication. A low SNR, on the other hand, means that interference is making it difficult for devices to distinguish valid signals. This causes packet retransmissions, latency, and throughput drops. Nearby wireless networks, microwaves, Bluetooth devices, and other electronics can all contribute to increased noise. Maintaining a healthy SNR is often more important than maximizing raw signal strength.
Power constraints on devices also contribute to wireless limitations. While access points can be configured to transmit at high power levels, client devices like smartphones and tablets have much lower transmit power capabilities. This creates asymmetric communication paths—where the client can hear the access point, but the access point cannot reliably hear the client. This mismatch leads to one-way communication, dropped packets, and failed handshakes. Adjusting AP transmit power downward can actually improve performance in these cases, encouraging clients to connect to closer access points with more balanced communication levels.
Mismatched power levels between access points and client devices are a common cause of unpredictable connection behavior. When access points operate at maximum power, devices may remain connected to a distant AP even when a closer one is available. However, because the client’s signal is weaker, the distant AP may not receive its transmissions consistently. This results in poor performance, delayed acknowledgments, and potential disconnections. Proper power balancing—adjusting AP power to match client capabilities—ensures that clients connect to the most appropriate access point and maintain stable bidirectional communication.
Another major source of performance problems is interference from non-Wi-Fi devices. In the 2.4 GHz band, microwaves, cordless phones, baby monitors, and Bluetooth devices can create noise and disrupt wireless signals. These sources generate energy in the same frequency range but don’t follow Wi-Fi protocols, so access points can’t detect and avoid them easily. The result is increased noise floor and packet collisions, especially on crowded channels. To detect these sources, a spectrum analyzer is required. These tools scan the entire frequency band—not just Wi-Fi channels—and identify spikes, interference patterns, and persistent noise sources.
Environmental obstacles also limit wireless signal performance. Physical barriers such as walls, doors, and furniture can absorb or reflect signals, reducing coverage. Metal objects, water, and even glass can significantly affect signal propagation. The effect varies by frequency—higher frequencies like 5 GHz offer higher data rates but are more easily absorbed or blocked. Lower frequencies like 2.4 GHz penetrate better but are more susceptible to interference. Understanding how materials affect signal behavior is crucial when designing or troubleshooting wireless environments. In many cases, simply moving an access point a few feet can dramatically improve performance.
One of the most frequent causes of poor wireless performance is improper placement and orientation of access points. An access point that is placed too low, too high, behind thick walls, or inside metal enclosures may provide weak or inconsistent coverage. Wireless signals radiate in specific patterns depending on the antenna type and its orientation. Omnidirectional antennas broadcast in a 360-degree horizontal pattern, while directional antennas concentrate energy in a specific direction. Placing an AP on the floor or behind equipment wastes signal strength and increases the chance of coverage gaps. Proper placement should aim for open, central locations with minimal obstructions and good line of sight to intended coverage areas.
Overlapping access points operating on the same or adjacent channels can create co-channel interference, especially in the 2.4 GHz band where there are only three non-overlapping channels (1, 6, and 11). When multiple APs use the same channel in close proximity, they must wait for each other to transmit, increasing contention and reducing throughput. Auto channel selection helps, but it’s not always perfect—especially in dense environments. Manual channel planning ensures that neighboring APs operate on different channels and distribute clients more evenly. In the 5 GHz band, more channels are available, but DFS restrictions and environmental factors still require thoughtful tuning.
Band steering is a feature designed to improve network efficiency by pushing capable devices to the less congested 5 GHz band. However, not all devices respond predictably. Some remain stuck on 2.4 GHz despite strong 5 GHz coverage. Others may flip between bands too frequently, leading to disconnections or reduced stability. In cases where band steering is ineffective, manual network configuration may be required—such as separating SSIDs or adjusting signal thresholds to encourage better band selection. Testing how client devices behave under different settings helps fine-tune the wireless experience in mixed-client environments.
Roaming issues are another common limitation in wireless networks. Ideally, clients move seamlessly between access points without losing connection. In reality, many clients stay connected to a distant AP long after a closer one becomes available. This results in degraded performance or complete dropouts between zones. Roaming behavior is controlled more by the client device than the AP, which limits the ability of network administrators to enforce handoffs. Heatmaps and wireless planning tools can help design better overlap zones, and protocols like 802.11r (fast roaming) can improve the client experience—when supported by both infrastructure and endpoint devices.
Users located near the edge of a wireless cell often experience lower throughput, even if they still have a signal. This is due to modulation and coding schemes that adapt based on signal quality. As signal weakens, the wireless protocol switches to more robust but slower transmission rates to preserve reliability. So even though a client at -75 dBm might still be connected, its effective throughput could be a fraction of what’s available closer to the AP. This is why performance drops even though devices show two or three bars of signal. It’s not just signal strength—it’s the quality and clarity of that signal that determines speed.
When troubleshooting power and signal-related wireless issues, the most effective tools are site survey apps and spectrum analyzers. These tools allow you to visualize signal strength from both the access point and the client perspective, measure channel saturation, and detect interference sources. Mobile apps can show which SSIDs are present, what channels they use, and how their signal levels change throughout a space. Spectrum analyzers go further by revealing non-Wi-Fi interference, such as from microwave ovens or security systems. Technicians should use these tools to validate real-world signal behavior—not just rely on controller dashboards or default settings.
From an exam perspective, understanding wireless limitations is essential. You’ll need to identify the cause of slow speeds, disconnections, or low throughput based on signal strength, interference, or power imbalance. You may be asked to recommend adjustments based on a described scenario—for example, increasing AP count, reducing transmit power, changing channels, or separating SSIDs. Questions may also ask about ideal signal ranges for specific applications like VoIP or video. Knowing the difference between a coverage issue and a capacity issue, and how power settings affect communication, will give you an edge on the test.
In summary, wireless networks are constrained by physical realities—distance, interference, and signal quality all impose limits that no amount of configuration can completely eliminate. Understanding how signal strength, SNR, channel planning, and client behavior affect performance is key to delivering a reliable wireless experience. Measurement tools provide the visibility you need to diagnose these issues accurately and recommend meaningful improvements. Whether you're troubleshooting a single AP or optimizing an enterprise deployment, knowing how these wireless constraints behave will make your work faster, smarter, and more effective.
Wireless issues are some of the most common tickets in IT support, yet many are solved with simple insight into signal strength, interference, and power levels. Tools like heatmaps, spectrum analyzers, and site survey apps make the invisible visible. They help you understand not just whether the signal is present, but whether it's strong enough, clean enough, and evenly distributed. When troubleshooting Wi-Fi, always start with physics. Wireless is flexible, but it's not magic. Understanding its limitations gives you the power to make it work better—for your users and your infrastructure.