If you are experiencing WiFi performance problems or are designing a new network, the RF of your environment needs to be surveyed. So you probably already figured out that this means getting a wireless site survey.
But how exactly are site survey performed?
In this post, you’ll learn:
- What are the different types of site surveys?
- What’s happens during a WiFi site survey?
- What are the common findings of a site survey?
- What kind of recommendations can I expect from a site survey?
What are the different types of site surveys?
If you’re serious about uncovering what’s wrong with your wireless network design, you'll first need to understand the four different kinds of site surveys that address WiFi concerns
Predictive Site Survey |
A predictive site survey is performed with simulation software to create a model of the radio frequency (RF) environment using your floor plans. It models your environment and creates different types of WiFi heat maps, making it very cost-effective and highly accurate.
Use Case: Regular office space environments or new network designs.
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WiFi Site Survey
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A WiFi site survey is a physical on-site survey of your network and starts with a predictive site survey but then WiFi engineers then visit the location to measure things like noise inference and measure applications performance that roam across access points (APs) Use Case: Complex environments (i.e. Hospitals and Warehouses) or when you're experiencing a WiFi problem
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Passive Site Survey |
A passive site survey is when you use software to passively listen to traffic on your wireless network. You don't hook into any access points, you just use a separate device to scan what's happening . It looks specifically for problems with access points, signal strength, and environmental noise. However, it Use Case: Quick budgetary option for small businesses experiencing a WiFi problem (although sometimes included in WiFi Site Survey)
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Post-Validation Site Survey |
A post-validation site survey is used to to ensure that your WiFi network is performing at the level it was designed to perform. Use Case: Used after any the other 3 wireless site surveys |
However, the main two types of site surveys are the predictive site surveys and the WiFi site surveys.
What Happens During a WiFi Site Survey?
So now that know you about the four different categories of site surveys, what can you expect when you invest in an onsite WiFi site survey?
Expert wireless engineers will:
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Manually inspect wireless hardware, including mounting and orientation.
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Run wireless analysis software to capture data on your wireless network
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Asses and analyze all data captured
- Present data in a report
The report includes the following information:
- Purpose - The reason why is this wireless site survey being conducted.
(It could be to determine if RF coverage shown in a Predictive RF design matches what’s seen during the survey or to review the current wireless network design and identify sources of ongoing performance problems.) - Scope - Which tests were run in this assessment and which were not included.
- Survey Test Infrastructure - The hardware and software tools are being used to measure RF coverage.
- Signal strength - The measurement of power from the perspective of your WiFi enabled device. Learn more about signal strength.
- Signal-to-noise ratio - A ratio of signal power in comparison to unwanted "background" RF noise.
- Data rate - The speed of data reaching the devices.
- Co-channel interference - An analysis that identifies any crosstalk between two different transmitters on the same RF channel
- Adjacent channel interference - An analysis that identifies any extraneous power from a signal on an adjacent RF channel.
- A floor plan listing routes for the site survey
- Number of Access Points and their locations
- Coverage and performance narrative including:
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- Data rate heat map for both 2.4 GHz and 5 GHz wireless frequencies (the highest possible speed that a wireless device can transmit data)
- Maximum effective throughput heat map for both 2.4 GHz and 5 GHz wireless frequencies (Due to its half-duplex nature, true data throughput tends to be about half of the data rate.)
- RF signal strength/coverage heat map for both 2.4 GHz and 5 GHz wireless frequencies (the most basic measure of wireless networking health that can often explain problems with unreliable connections and low data throughput)
What are the Common Findings of Site Survey?
One of the most common goals in a site survey is to identify what is negatively impacting the network performance.
These findings can include:
1. Access points were deployed for the wrong purpose
For example, during a recent wireless site survey, one company was using the incorrect models of APs in many locations throughout their facility. Because these APs were using omni-directional antennas and the APs were installed on 20-30 foot ceilings, devices being used at ground level ended up with very low signal levels.
2. RF cell overlap problems between access points
Again because this same company had omni-directional antennas on its APs, there were too many RF cell overlaps between the APs. When the devices saw multiple APs using the same channel, wireless devices on the network essentially had to wait in line for their turn to use that channel.
3. Identifying a coverage void or null with outdoor APs
This could be due to bad decisions on mounting heights -- basically poorly thought out wireless network design. In this case, changing the AP height altered its coverage because of the antenna’s vertical beam width.
4. AP power levels left at default configurations
By not customizing the power levels to be symmetrical with power levels achievable by client devices, performance suffers.
5. APs installed/mounted at troublesome locations
When mounted too close to objects that block or alter the RF signal, signal delivery to client devices takes a hit.
When one or more of these findings are acted on and implemented, companies generally see an immediate and dramatic improvement in their wireless network performance.
What Kind of Recommendations can Site Surveys Offer?
From these findings, the wireless network design engineers will introduce recommendations that remedy as many of these problems as possible including:
- Better suited AP models - Reason Ex: AP models could not adapt to the client’s environment and did not suit their needs.
- New indoor RF wireless network design - Reason Ex: An indoor design didn't take into account emerging software application requirements or new construction changed the RF propagation in which a new indoor design is needed.
- New outdoor RF wireless network design - Reason Ex: The design might have not accounted for reflective objects or attenuators so a new outdoor design is needed.
- Removing channel bonds as needed - Reason Ex: This could be recommended to limit the possibility of channel reuse and all the co-channel and adjacent channel contention problems that crop up.
- Removing lower data rates - Reason Ex: This could be recommended to improve the design of the wireless network by forcing devices to use closer APs with better signal strength.
- Setting/optimizing symmetric power levels - Reason Ex: The network may not have been designed to match the lowest power client device.
- Improving AP mounting - Reason Ex: The APs might not been mounted in the correct position therefore required to be moved for improved RF signal delivery.
- Improving bridge/mesh links - Reason Ex: The wireless mesh is splitting the function of the router, so separate access points may need to be used or dual band routers in order to greatly improve signal quality.
Final Thoughts
Wireless site survey can provide IT professionals with valuable insights about the performance of their wireless network. From the detailed report, you’ll learn what needs to be addressed to improve end user experience and overall system performance.
A well-executed site survey also gives you a baseline to measure future wireless network design improvements against -- to help document specific performance upgrades.
It's also important to not overlook the importance of partnering with a service provider that has the right certifications in WiFi.
If you're interested in how much a predictive design or a WiFi site survey costs, check out our professional services calculator.
