WiFi site surveys are instrumental in ensuring a seamless Wireless Local Area Network (WLAN) deployment. As an experienced network engineer, I’ve spent years understanding their intricacies and the crucial role they play in network planning and optimization.
This article offers a comprehensive guide to WiFi site surveys, discussing everything from planning and execution to post-survey troubleshooting and management.
Understanding the Basics
Before we delve deeper, let’s first establish what a WiFi Site Survey is. It’s an assessment of RF (Radio Frequency) behavior in a specific environment, aiding in the planning and ensuring comprehensive WLAN coverage. There are three primary types of site surveys: Passive (listen-only mode), Active (involving client association with Access Points), and Predictive (software-based AP placements). Each type serves a unique purpose and is selected based on the specific needs of your deployment.
Preparation for Site Survey
The first step towards conducting a successful site survey is identifying the primary requirements: RF application needs, facility type, client devices, and industry vertical. These requirements inform the survey preparation process and ensure the deployed WLAN aligns with your specific needs.
For instance, facility layout (single-floor, multi-floor, campus, warehouse) heavily influences AP placement and signal propagation. Always remember to obtain digital floor plans; they provide valuable spatial information that guides your survey.
As a pro-tip from years of experience, I cannot overstate the importance of avoiding common mistakes like improper map calibration. If the map isn’t correctly calibrated, you risk inaccurate heat maps, potentially leading to sub-optimal WLAN deployment. Always verify the map calibration and cross-check the actual survey data files with the survey report.
Execution of Site Survey
The next step is executing the survey. It begins with an initial walkthrough of the site to identify potential problem zones. Defining the type of survey (Data, Voice, Location) is crucial here, as it guides your subsequent actions. Tools like Cisco Spectrum Expert, Airmagnet Survey, or Ekahau Site Survey are invaluable in conducting a thorough survey.
Remember, the client devices that will be deployed, their maximum transmit (Tx) power, receiver sensitivity, and antenna type, significantly influence the WLAN’s performance. Physical requirements such as power supply, cable considerations, and mounting and fastener considerations are often overlooked but can affect the network’s operation significantly.
Signal Propagation and Path
A critical aspect to consider during the survey is signal propagation. Incorrect settings could lead to underestimations or overestimations of signal coverage. An optimal setting of 15 to 20 feet is generally recommended for accurate results.
When conducting the survey, the path you follow matters immensely. I can’t tell you how many times I’ve seen inadequate WLAN performance due to overlooked areas during the survey. Collect data points in all desired coverage areas, including smaller rooms and offices.
Understanding how changes in wireless data rates impact the environment is essential. The choice of data rate directly affects coverage and performance. Lower data rates can be demodulated across greater distances than higher data rates, allowing you to adjust the effective range of the AP.
Capacity Considerations and Channel Scans
A key aspect of site surveys is understanding capacity needs. In high client density areas like conference rooms, capacity planning becomes even more critical. It’s also necessary to check which applications the client devices will be using to understand the bandwidth requirements.
During the survey, ensure that all in-use channels are included in the channel scan list. Scan only for SSIDs provided by the wireless infrastructure, and use a client adapter that closely matches the characteristics of the devices that will be used in the network.
After the site survey, a post-validation survey is conducted to assess the current RF coverage, identify sources of interference, equipment placement, and rogue devices. Coverage, overlap, signal-to-noise ratio (SNR), noise floor, bleed-through, rogue APs, and interferers should all be checked in this stage.
I highly recommend using the Wireless LAN Controller (WLC) link test tool to assess the sufficiency of the current AP coverage for the applications running on a client. It can provide invaluable insights into your network’s performance.
Managing WiFi Deployments
The management of WiFi deployments involves a delicate balance between range and performance. In dense deployments, increasing the range can lead to co-channel interference, reducing overall throughput. Conversely, reducing the range can enhance performance but may sacrifice coverage. As a rule of thumb, strike a balance based on the desired AP density and the requirements of the clients/applications.
Management frames, sent at the lowest mandatory data rate, can consume a significant portion of airtime, leaving less bandwidth for clients. To optimize network performance, consider lowering the number of SSIDs and disabling lower data rates.
Multicast/Broadcast frames are typically sent at the highest mandatory data rate, but remember, the AP will adjust to send at the highest rate equal to or lower than all client transmission rates. This can impact multicast performance, particularly if some clients transmit at lower rates.
Troubleshooting and Optimization
Finally, let’s talk about troubleshooting and optimization. Common issues include poor coverage, high channel utilization, large numbers of SSIDs, and multicast traffic. For signal strength verification, software applications like inSSIDer or Cisco 792x Wireless Phone are useful.
The best strategy for enhancing network performance often lies in minimizing unnecessary network traffic. Reduce the number of SSIDs to the minimum required, use QoS to prioritize traffic, limit low data rates, and optimize channel utilization.
Now, after understanding the complexities involved in conducting a WiFi site survey and managing WiFi deployments, you might be considering the benefits of leveraging professional services. Global Associates Tech Network is a company I’d strongly recommend.
They are seasoned professionals in WiFi site surveys and WiFi design. Their years of experience and in-depth understanding of RF behaviour and WLAN deployment uniquely position them to tailor solutions to your specific needs.
By incorporating the principles discussed in this article into their rigorous approach, Global Associates Tech Network (GATN for short) ensures your WiFi network is designed for optimal performance. With their help, you can focus more on your core business activities while ensuring that your WiFi infrastructure is in capable hands.
Conducting a WLAN site survey and managing WiFi deployments is both an art and a science. As this article has shown, it requires a keen understanding of the many facets involved and a balanced approach tailored to your specific environment and requirements. Always remember: even the smallest considerations can have a significant impact on your WLAN performance. Armed with this comprehensive guide, you’re now equipped to plan, deploy, and maintain a WLAN that delivers optimal performance.