Conducting a Site Survey
By Shelley M. Latreille
This is a paper that I wrote for my Wireless Networking Class. It revolves around conducting a wireless site survey for a fictional college called Wardlowe Community College. They are unhappy with their wireless network's performance and would like to improve it.
Wardlowe Community College is a small, inner-city, higher education institution. The student population consists entirely of students who commute to campus. The school is located within two high-rise buildings, which sit next to one another on the same city block. The Wardlowe IT Department consists of only two employees. They are seeking expertise in determining their wireless networking needs. Wardlowe has been increasingly unhappy with its WLAN (Wireless Local Area Network) performance. Wardlowe would like to see how their WLAN issues can be improved. They would also like to know how a site survey can benefit them, the steps required for a site survey, and the types of analysis that will be used during the site survey.
Conducting a wireless site survey is of vital importance to Wardlowe and will provide them with many benefits. A site survey that is performed properly will make sure that their wireless network will perform efficiently and possess the ideal coverage and performance. Site surveys identify the appropriate amount and placement of APs (Access Points), along with any sources of radio interference (Ridzyowski, 2019). A site survey will obtain information on current network performance. The survey will provide information on what should be addressed so that end user experience can be greatly improved, along with overall system performance. The survey provides a standard that can be used to measure future wireless network design improvements against. This will assist with documenting specific performance upgrades. A site survey assists with identifying configurations that would have a negative impact on Wardlowe’s network performance. Site surveys assist with detecting APs that are implemented for the incorrect purpose, detecting RF (Radio Frequency) cell overlap problems between APs, detecting a coverage void with outdoor APs, detecting AP power levels left at default configurations, and detecting APs installed or mounted in problematic locations (Pierce, 2018).
When configurations that negatively impact the performance of the network are found and corrected, Wardlowe would typically see a quick improvement in network performance. There are several improvements that can be implemented. These improvements include improved AP models that have antennas that are able to quickly adapt to Wardlowe’s environment and needs, a new indoor RF wireless network design that will include emerging software application requirements, a new outdoor RF wireless network design that will do well in outdoor spaces where there are no reflective objects or attenuators, removing channel bonds to limit channel reuse and all the co-channel and adjacent channel contention problems that might occur, removing lower data rates to improve the wireless network’s design by forcing devices to use closer APs with better signal strength, optimizing symmetric power levels to match the lowest power client device, improving AP mounting for improved RF signal delivery, and improving bridge and mesh links to greatly improve signal quality (Pierce, 2018).
There are nine steps that can be performed at Wardlowe to assist with the site survey. The first step in a wireless site survey is to identify all wireless and network needs. Before the site survey can be performed, Wardlowe must provide information on their wireless network requirements, preferred speed and bandwidth, number of client devices that will need to access the network at the same time, amount of transmit power they have, and the generation of 802.11 Wi-Fi standard they use. The second step is to obtain a floor plan. The area that the wireless network will cover must be diagramed. The diagram should include the location of walls, stairwells, elevators, and anything else that could block wireless signals. Building blueprints can be used for this. The third step is to perform a physical walkthrough of Wardlowe’s buildings. A full walkthrough must be done in each building because floor plans won’t show all the information needed. During the walkthrough, the entire wireless coverage area should be viewed. Anything that wasn’t on the blueprints should be notated. For example, modular walls and metal equipment racks can weaken wireless signals (Ridzyowski, 2019).
The fourth step is to evaluate Wardlowe’s current infrastructure. Locations where wireless APs can be placed should be notated. The locations of the existing wired network closets and existing APs should be notated. Wireless APs can be placed on ceilings and pillars. The fifth step is to identify the areas that will be covered. The goal of this step is to ensure that Wardlowe will have a network that is efficient, reliable, and high performing. This is a strategic step where locations that require network coverage must be notated. Locations where high bandwidth will be needed the most must be notated. Offices, conference rooms, classrooms, cafeterias, and break rooms usually will require high bandwidth. Also, it must be determined whether Wardlowe will need good network coverage in their hallways, bathrooms, stairwells, and elevators. Utility rooms that house wireless equipment should be notated on the floor plan. The sixth step is to propose the locations of APs. Steps one through five should be reviewed and used to come up with locations for APs. The coverage range of all APs should be verified. Seamless roaming, dynamic load balancing, and network resiliency should be guaranteed. This can be accomplished by creating overlap between neighboring APs (Ridzyowski, 2019).
The seventh step is to conduct a wireless site survey. To conduct the survey, wireless site survey software can be installed on a laptop or specific survey tools can be purchased and used to conduct the survey. Using either method, wireless APs are placed in each of the proposed locations. The survey tools are used to obtain data in different spots by physically walking around with them. The software records what each AP is connected to, the transmission rate, the signal strength, and the signal quality. A survey will be most useful the more thorough it is. The eighth step is to improve AP locations. The data obtained from the wireless site survey in step seven should be used to find the best possible locations for the APs. This step will help make the network even better once the new and improved network is completed and put in place. The ninth step is to record all data obtained from the site survey in all the steps listed above. When the best possible locations have been selected for the APs, these locations should be written on the floor plans as an AP installation guide. Now the wireless network should be successfully designed and ready for implementation (Ridzyowski, 2019).
Wireless site surveys include several different assessments so that the most information can be obtained from the survey. As noted in the steps above, the survey begins with an onsite visit to Wardlowe to view their network’s design. A manual inspection of wireless hardware, along with an inspection of their mounting and orientation will be performed. Wireless analysis software is run in order to assess wireless performance. There are several different kinds of survey assessments that can be performed, which include Predictive, Physical, Post Validation (Pierce, 2018), RF Coverage, Coverage Analysis, AP Placement, Spectrum and Protocol Analysis, and Coverage Assessment (Doherty, 2016). After the survey and assessments are completed, the information is presented to Wardlowe in the form of a report (Pierce, 2018).
When a Predictive Site Survey is conducted, a model of Wardlowe’s RF environment is developed using simulation tools. It is also helpful to view each building’s blueprints and / or floor plans to ensure that Wardlowe gets the most out of their site survey and will obtain an accurate network design. This survey is accurate, cost effective, and efficient. Predictive Site Surveys won’t assess what Wardlowe currently has in their network environment or provide information on why they are having problems with their network.
When a Physical Site Survey is conducted, applications that are sensitive to latency and applications that roam across APs are focused on. When a Post Validation Site Survey is conducted, the Wi-Fi network’s performance is evaluated to test whether it is performing at the level it is designed to perform at. A Predictive RF design could be an efficient plan to implement when the network isn’t complicated (Pierce, 2018).
RF Coverage determines how RF radiation will behave within Wardlowe’s buildings. An RF Coverage Survey reviews the coverage, interference, and gaps based on how and where antennas are placed. It also reviews device power requirements. A Coverage Analysis Survey collects information on site coverage and capacity. This survey will assist with developing Wardlowe’s capacity and coverage needs based on the population that is contained within each building’s network area. This will help find out if smaller cells, larger cells, or collocation are needed. The stations’ density, applications used, and whether roaming is needed will be reviewed. A Coverage Analysis Survey uses RF signal strength, which can be found on a laptop or any other devices that can connect to an 802.11 network. An AP Placement Survey will evaluate where each AP is located within Wardlowe, along with each AP’s boundary. The position of each AP is verified to make sure that it is within reach of a network wiring closet. For example, Ethernet’s restriction on distance to the wiring closet is 100 m with Cat 5 cabling. To obtain the best network coverage, both omnidirectional and semi-directional antennas should be used. Coverage should not go beyond the transmission boundary that Wardlowe has set up. Using both types of antennas allows for adequate RF coverage, which will meet Wardlowe’s boundary requirements, along with restricting all unnecessary dissemination or pollution of the RF signal (Doherty, 2016).
A Spectrum and Protocol Analysis identifies RF interference that could cause a conflict with Wardlowe’s WLAN. A spectrum analyzer tool is used to perform this survey. The spectrum analyzer measures the amplitude and frequency of electromagnetic signals or radio waves. This survey provides a map of the RF activity that is currently present within the 2.4 GHz and 5.0 GHz channels. If any undesirable RF activity or radiation exists on either the 2.4 GHz or 5.0 GHz channel and it is greater than 85 dBm, then the wireless network will have performance issues. One of these issues could include a degraded signal. This survey can detect whether Wi-Fi signals are going outside their specified range. Wi-Fi coverage must meet Wardlowe’s specific needs. The Wi-Fi coverage range should not reach beyond those needs. It is important to know where the signal is being degraded in the RF environment. Knowing the RF qualities, along with where the 802.11 WLAN is placed will help to avoid placing it in an environment filled with noise, interference, and corrupted data transmissions. It will help to ensure that the WLAN has high availability and reliability. There are many causes of noise and interference, which include microwave ovens, cordless phones, fluorescent light bulbs, elevator motors, Bluetooth radios, other 802.11 wireless networks in the area, and malicious transmitters or signal jammers (Doherty, 2016).
A Coverage Assessment Survey evaluates network coverage. This survey is completed after site coverage and capacity have been evaluated and all APs have been placed and enabled. This survey can be conducted manually or by using predictive analytics. A manual coverage assessment can be performed either passively or actively. When passive mode is used, a client card is used to gather the RF measurement of receive signal levels, signal noise, and signal-to-noise ratios. The card provides raw numbers and does not provide information on the connection’s quality. The card doesn’t connect with the APs. When active mode is used, the client station will validate and connect with APs located at Layer 1 (Physical Layer), Layer 2 (Data Link Layer), and Layer 3 (Network Layer) of the OSI Model (Open Systems Interconnection Model). Active mode will evaluate upper-layer performance, which includes packet loss, latency, and jitter. This will provide information on connection quality, along with raw numbers. A Predictive Coverage Survey uses predictive modeling applications and simulation software. This technique allows visual models of the RF cell coverage to be created. An algorithm is used to predict the cell sizes (Doherty, 2016).
All the data captured during the site survey is analyzed and evaluated. It is then be presented to Wardlowe in the form of a report. The report contains a variety of different information on their network. It contains the purpose of the site survey, including its goal and why it was conducted. Many site surveys are conducted to ascertain if RF coverage displayed in a Predictive RF design is the same as the results obtained during the survey. Site surveys can also be used to evaluate Wardlowe’s current wireless network design and detect performance problems. The report contains the scope of the survey and states what items were included, and which ones were not. The report lists the survey test infrastructure that was used to conduct the survey, including the hardware and software tools that were used to measure RF coverage (Pierce, 2018).
The report outlines several different requirements. These requirements include signal strength minimum, signal-to-noise ratio minimum, data rate minimum, and the minimum number of audio APs. Wardlowe’s floor plan listing will list routes for the site survey, along with AP locations. The report includes information on coverage and performance for 2.4 GHz and 5 GHz wireless channels, such as a data rate heatmap, maximum effective throughput heatmap, and an RF signal strength / coverage heatmap. The site survey can also include a CCI (Co-Channel interference) assessment, which will detect crosstalk between two different transmitters on the same RF channel and an ACI (Adjacent Channel Interference) assessment that will detect extraneous power from a signal on an adjacent RF channel. Typically, during a site survey, a floor plan with AP locations, data rate heatmap, throughput heatmap, and signal strength heatmap will be developed for each floor in both buildings at Wardlowe (Pierce, 2018).
Wardlowe can benefit from a site survey. They are unhappy with their network performance and would like advice on determining their network needs. A site survey would provide them with all this information. The survey would help to improve network performance and ensure that all devices on the network are properly placed within Wardlowe’s network boundary. Useful assessments that should be performed during the site survey to help improve network performance and determine network needs include Predictive, Physical, Post Validation, RF Coverage, Coverage Analysis, AP Placement, Spectrum and Protocol Analysis, and Coverage Assessment. Wireless site surveys should be performed on a regular basis in order to preserve high network performance, availability, and reliability. AP locations may need to be modified from time to time because the radio environment may change as new wireless devices and / or other new equipment are added to the network (Ridzyowski, 2019).
Doherty, J. (2016). Wireless and Mobile Device Security (1st ed.). Burlington, MA: Jones & Bartlett
Pierce, M. (2018, September 05). What’s Included With a Wireless Site Survey? Retrieved from
Ridzyowski,T. (2019, April 09). The Ultimate Wireless Site Survey Checklist. Retrieved from Turn-Key