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Difference between a predictive and a validation survey in Wi-Fi

Wi-Fi is a networking technology that uses radio waves to allow high-speed data transfer over short distances. It is usually the first point of contact with the rest of the network in the broadband internet. It also provides access to a local network of connected devices that print pictures wirelessly and stream videos from Wi-Fi-connected cameras without any physical connection.

Statistics from cisco show that globally, there will be nearly 628 million public Wi-Fi hotspots by end of 2023, up from 169 million hotspots in 2018, a four-fold growth from 2018 to 2023.

A Wi-Fi site survey can also be called a WLAN survey, wireless network survey, RF site survey, or networking site survey.

The primary reasons for conducting a Wi-Fi site survey are to:

  • Find areas of RF coverage and interference

  • Determine the placement of access points (APs)

  • Visualize wireless coverage areas and know where the signal will be strongest.

A Wi-Fi survey assesses the environment to determine proper Wi-Fi coverage, less downtime, data rates, roaming capability, and quality of service.

What is a predictive design?

Predictive Design is one of the first steps to take when expanding an existing deployment, upgrading, or planning for a new wireless network solution. A predictive design, also known as a predictive survey, uses special software to create a virtual representation of the supposed site and predicted RF environment.

For a proper complete predictive wireless design, it is necessary to have an accurate idea about the site layout, type of materials and RF attenuations, applications that will be used, the type of devices that will be on the network and an estimate of the total number of users/devices.

The predictive design will consider all these information and import it into a wireless network planning software. The software will consider the size of the facility, the building materials and how they affect RF, the types of access points and antennas, and several other criteria to model a predicted wireless network.

One of the most critical pieces of information a predictive wireless design provides is the project's expected cost, which will most likely be a budgetary estimate. The success of a wireless network project is often associated with the quality of the design.

What is a validation survey?

A validation survey is an on-site survey that captures Wi-Fi signal, spectrum data, and inspects access point mounting and cabling accessibility. Validation surveys can be conducted before deployment and installation to test the predictive wireless design or after the installation to see how the overall result looks like, verify that changes or additions are correctly installed, and ensure that the network is reliable for users and applications.

When implementing a predictive design before validation, the risk of over-engineering or under-engineering is inevitable. It is expensive to fix wireless network plans that are either under-engineered or over-engineered.

The term “validation survey” can mean different things to different people, but scenarios that involve a validation survey include the following:

  • Wi-Fi Design Survey: This is a site visit before the predictive wireless design begins. This survey captures existing RF conditions, including neighboring networks, available and congested channels, interference, and accessibility for mounting access points (APs).

  • Pre-Deployment Site Survey: This is a site survey carried out when the Wi-Fi network has been designed. Also known as an AP on a Stick Wi-Fi survey, it simulates the performance of antenna and access points. Here, an access point is placed temporarily in the location and configuration of the design, and the Wi-Fi is analyzed to ensure it performs as anticipated in the predictive design.

  • Post-Deployment Site Survey: This survey checks whether the network has been deployed and configured correctly and that the performance meets the predictive design's expectations.

  • Health Check Survey: This maintenance survey periodically checks Wi-Fi performance over a particular time range so that it can spot potential interference, coverage, or capacity problems on time before they become costly outages.

  • Troubleshooting Wi-Fi Survey: This survey is done when users experience network issues. It is a more reactive survey that identifies the underlying cause of the problems end users report and affect them immediately.

Difference between a predictive design and a validation survey

The biggest difference between those two types of survey lies in the fact that the predictive survey is a “simulation”. The main goal behind it is to determine the type and quantity of Wi-Fi infrastructure elements needed (APs, Switches, Cabling, etc.) and the initial RF configuration that can be used during the deployment (before optimization). On the other hand, a validation survey will show the “real” RF parameters such as signal strength, interference levels, signal to noise ratio, channel utilization, etc. Other noticeable differences are:

- The predictive design does not require physical access to the location area that needs a survey. It is a huge advantage in situations where there is limited access to the survey area. In contrast, a validation survey is an on-site survey. There must be a visit to the location where the network deployment will take place. This is where the wireless network design will be tested, and the outcome, whether it works or not, will be known.

- Predictive network designs use facility blueprints and other vital information to produce accurate plans for the ideal placement of wireless access points. In contrast, validation surveys produce the data needed for delivering those detailed network designs. These data must accurately represent the present state of the surveyed area; otherwise, it will most likely lead to poor network performance and security issues.

- Predictive design is less costly than actual surveys as it is easier to model with special software. Also, predictive design is less time-consuming, and takes less effort to make adjustments to the design.

Importance of both predictive design and validation survey of Wi-Fi

Predictive designs and on-site surveys are vital to successfully deploying any wireless network project. They go hand in hand to ensure the proper performance of Wi-Fi solutions.

The predictive survey is important to decide on the proper placement of the Wi-Fi APs, generate the bill of materials and know what to expect from the solution. Skipping this phase can usually result in over or underestimating the project budget and a lot of wireless issues after the deployment (coverage holes, roaming problems, etc.)

The post-installation survey is critical to adjust the RF configuration and detect any Wi-Fi issue before putting the wireless in production. It also serves as a support for troubleshooting and isolating wireless issues post deployment.

At Altis technologies, we have designed and validated Wi-Fi solutions for customers in several industries for almost a decade. We proud ourselves of having expert-level knowledge on enterprise Wi-Fi. If you are looking to design or expand your wireless infrastructure, need help to solve any Wi-Fi issues or just have questions about what we do, please feel free to contact us.

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