In last month’s blog we covered some of the upcoming access point features, one of which was a dedicated site survey mode on Meraki access points (APs). We covered an introduction to wireless site survey early last year with “From Site Survey to Flawless Wireless Connectivity”, but in this post we will further examine site surveying and how to use this new feature in more detail.
Designing a Wireless Network
The end goal of any site survey is to ensure the most optimal configuration of the wireless network for the given requirements. These requirements can differ from physical location to physical location and can even vary within different areas of a location. Often the requirements have to be balanced against each other to reach the most optimal outcome. The requirements can include:
- Specific support for high density or real-time applications like voice
- Location services and positioning
- Outdoor coverage
- Minimization of interference with other networks or RF signals
Designers of wireless networks have a number of tools in their armory to meet these requirements. Some of the areas a designer can control are:
- The location of the APs
- The number of APs
- The transmit power of the APs
- The channel the APs use
Site Survey – a Designer’s Best Friend
Due to the nature of radio waves, it can often be hard to visualise how aspects of your design will work when viewed as a collection of numbers and PDF specifications. The physical environment also has a major impact on how you design the deployment and how the APs will work. Enter the site survey and fantastic site survey tools such as Ekahau’s Site Survey and Fluke Networks AirMagnet.
These applications and others like them, allow you to visualize your WLAN deployment before, during, and after its deployment. Invisible radio waves become easy to understand with colorful heatmaps. Site surveys can be divided into three types that are typically carried out in order; predictive, pre, and post site surveys.
Predictive surveys use floor plans, estimates of building materials, and advanced algorithms to predict how the wireless network will look. This is based on the number of APs, their location, and their configuration.
Pre-site surveys allow the wireless designer to accurately record the reality of the physical environment where the WLAN will be deployed. This can then be used to prove, or disprove the validity of the design that is often created by a predictive site survey. The pre-site survey is typically carried out by placing an access point of the model you wish to use, with the configuration you think is appropriate, in different locations in the building. At each location the wireless is surveyed by taking readings using the site survey software. This then uses the information to update its model of the design.
Finally a post-site survey repeats the measurements taken by the pre-site survey but this time with all the APs for the final deployment in place. This survey is used to prove the design is correct or help identify adjustments that need to be made.
Although it is not essential to carry out all types of site surveys, it is generally recommended that at a minimum, a pre-site survey is carried out for any location with more than a handful of APs.
Listen to Ryan, a support engineer in the Meraki San Francisco office talk about the importance of surveying for your WLAN.
To perform a site survey with an AP, desired settings are typically configured before, then moving it between the locations that are being surveyed. The AP is often attached to a tripod or other type of stand to simulate the physical position it would have when deployed e.g. wall mounted or ceiling mounted. To make the movement of the AP easier, it is not normally attached to AC power and is instead powered by a portable battery pack.
Before the introduction of the dedicated site survey mode on the Meraki APs, it was necessary to include an additional equipment beyond just power. The reason for this was that the self healing auto mesh functionality built into every Meraki AP would try and repair the AP’s connection to the LAN. It does this by scanning for other mesh APs to communicate with when it can’t see a gateway. When this happened, it meant that site survey tools were not able get a reading.
The new site survey mode allows network admins to turn an AP into a dedicated device for site surveys. When enabled the AP will broadcast an open SSID named “site_survey-” followed by its MAC address. The AP can then have the channels and transmit power set for both 2.4Ghz and 5Ghz radios.
To access the site survey mode, wirelessly connect to the desired AP and enter ap.meraki.com into your web browser. Alternatively you can access the same page by entering the LAN IP address of the AP into your web browser.
This local management page on the AP is used for basic setup, troubleshooting, or for when a specific manual configuration is required. Choose the ‘Configure’ tab and enter the credentials requested by the login box. Once logged in, you can access the settings for the site survey mode.
Completing a site survey is often an essential step on the path to an efficient, high performance WLAN. Ensuring your deployment is right from the start can save many hours of troubleshooting and associated costs later on. The new Meraki site survey mode will help make this process simpler and easier for anyone going through this activity.