WiFi Site Survey to Determine Signal Quality (Post Implementation WiFi Validation Survey)
The United States Holocaust Memorial Museum (USHMM) completed a WiFi network installation for its Washington, DC museum locations and its collections facility in Bowie, MD in 2017. This WiFi implementation used Aruba/HP-Enterprise network hardware.. This wireless local area network (WLAN) was designed based on a predictive-model site survey to support 802.11n and 802.11ac IEEE standards. USHMM needed a post-implementation validation survey aimed at ensuring ample WiFi signal coverage to support the intended business functions of the Museum.
AccessAgility validated the new installation in the Museum building and the collections facility in Bowie. This included a thorough site survey which recorded detailed information about the current RF coverage environment to determine whether or not the facilities could support ample WiFi signal throughout each building. The survey also documented the coverage area of the existing WiFi implementation and identified any signal degradation caused as a result of RF interference factors and rogue devices. The Museum used the results of the survey to optimize its WiFi installation, creating a stable and reliable wireless infrastructure. The deliverables included, but were not limited to, an in-depth report of survey results along with a specific set of recommendations for configuring the network for best possible wireless coverage in each building. As shown below, our report focused on four areas.
Coverage
Coverage defines the ability of wireless clients to connect to a wireless Access Point (AP) with a signal strength and quality high enough to overcome the effects of RF interference. The edge of coverage for an AP is based on the signal strength and signal-to-noise (SNR) ratio measured as the client device moves away from the AP. Our deliverables included the following:
- The signal coverage document as measured in dBm
- A complete report including a graphical representation of the coverage overlaid on the floor plan for each floor
- Recommendations for AP placement changes if needed
- Recommendations for changes to AP transmit power to ensure uniform signal strength throughout the coverage area
Overlap
This part of the site survey determined whether the channel/signal overlap was adequate for devices to roam to the next AP before the signal would be lost from the previous AP. We used industry standard best practices and Aruba/HP-Enterprise documents as a reference to determine an acceptable percentage WiFi signal overlap. Our deliverables included the following:
- Documented report of wireless channel/signal overlap
- A heat map overlaid on each floor plan
- Recommendations for APs reconfiguration, if needed, to have an acceptable percentage of overlap in order to mitigate client devices dropping connection while roaming throughout the building
Signal-to-Noise Ratio (SNR)
Signal-to-Noise Ratio is the ratio of a transmitted signal to the background noise on its channel. The site survey was conducted using radio frequency (RF) guidelines specified in published documents from Aruba/HP-Enterprise and other industry best practices. Additionally, the signal validation survey factored in the background RF radiation already existing in the environment surrounding the system in use. Our deliverables included the following:
- Documented report showing Signal-to-Noise Ratio relative to background noise and other RF signals in the coverage area
- A heat map showing the results overlaid on a floor plan for each floor in each building
- Recommendations for AP adjustment, or reconfiguration, if needed, to maintain an acceptable signal-to-noise ratio.
Bleed Through
Since RF signal can bleed through walls and floors directly above and below, co-channel interference can occur. This part of the survey determined whether or not the placement of each AP was optimal to minimize this bleed-through effect. Our deliverables included the following:
- Documented report showing AP placements overlaid on the floor plan for each floor
- Recommendations to reposition, if necessary, to optimize the placement of each AP
Rogues and Interferences
Since unauthorized rogue APs are a source of co-channel and adjacent-channel RF interference, which degrades the performance of the enterprise WLAN, the validation survey included rogue AP detection. Our deliverables included the following:
- Documented report showing the presence of any rogue APs and their approximate location if feasible
- Recommendations to mitigate signal degradation due to rogue access points and other devices that interfere with the WiFi signal
AccessAgility is on the front lines of this type of work. Our existing relationship with the US government has allowed us to bring our WiFi services and products to multiple government agencies. Want to work with us? Reach out here.