3 Types of Wireless Network Site Surveys and How to Perform Them

Designing and maintaining a network is complex, but wireless networks are even more complex than wired networks. With a wired network, when you move a desk or a filing cabinet, the throughput doesn’t change, but that change can affect the wireless signal path and cause differences in wireless network performance.

To ensure adequate signal coverage and performance, enterprises should conduct wireless surveys. For a comprehensive assessment, three types of wireless site surveys are required, each of which performs a different function, as follows:

• Predictive Research – Conduct research before entering a new space.
• Passive survey – collects information about all signals in the environment after the wireless base station is built.
• Active investigations – focus on specific signals or groups of signals while the network is fully operational.

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Perform a predictive site survey

Before any equipment or furniture is moved into a new space, a predictive survey should be conducted. This survey is primarily performed with software packages designed to predict how wireless signals will propagate through the space. The input is a detailed set of blueprints and information about the type of wireless equipment proposed, such as which Wi-Fi standard will be used in the area.

The purpose of a predictive site survey is to determine where to place access points (APs) for optimal performance across an area. Virtual APs are placed on the blueprint, and the software determines signal strength based on information about how the signal propagates through walls and tables and cabinets. The type of applications that will be used in the area are also a consideration - for example, video requires high throughput, while VoIP calls do not require high throughput but do need to strictly limit latency.

Virtual APs can be placed automatically or manually. With automatic placement, the software chooses where to place the APs - using the same model everywhere. Manual placement lets network administrators choose locations and specify a recommended AP model for each location - for example, placing more powerful models in some locations and less powerful models in others.

Without a forecast survey, you will be guessing at the number of APs you will need and where to place them. While general rules dictate the number of APs you need per additional space, they do not take into account application performance requirements. For example, while APs are moved, added, or removed, and users come in and try to use the network, there may be continuous outages.

Perform a passive site survey

Passive surveys should be performed periodically after sites are built, equipment is installed, and the network is available. The purpose of a passive survey is to report all signals at each location, including installed networks and signals from neighboring sites or other devices that create noise on the wireless frequencies. These surveys contain information about the APs and their characteristics, signal strength, signal-to-noise ratio, and interference, and may reveal marginal performance changes before users notice them.

Perform proactive site surveys

Active investigations focus on a specific signal or a specific group of signals and build a comprehensive list of measurements for each AP that generates the signal under study. These measurements include signal strength, throughput, round-trip time, packet loss, and retransmission rate across the entire area where the signal is used. Active site surveys also measure upstream and downstream data rates and may result in moving APs or adding or removing unneeded APs. Active investigations should be performed when investigating network performance issues.

Who Performs Wireless Site Surveys

Each wireless site survey type can be performed by a company with specialized skills or in-house personnel. They can perform these surveys through software running on a laptop or with equipment designed specifically for wireless surveys.

Wireless networking technology has made steady progress and will continue to advance, and wireless networks are now required to support applications that previously connected to wired networks. Despite advances, wireless networks still require ongoing maintenance to ensure optimal performance.