Glossary

These definitions describe how common Wi-Fi terms are used throughout the Intuitibits guides. A product may display a more specific label when the distinction is important.

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Access point

A device that provides Wi-Fi connectivity to client devices. An access point may contain multiple radios and advertise multiple networks, SSIDs, or BSSIDs.

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Active scan

A method of discovering Wi-Fi networks by sending probe requests and processing probe responses from nearby access points. The bands and channels covered by an active scan depend on the scanning hardware, regulatory domain, and scan source. In WiFi Explorer Pro 3, explanatory text refers to this method as active scan mode. Linux-based sensors may support active scanning, passive scanning, or both. Android-based sensors support active scanning only.

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Band

A range of radio frequency spectrum allocated for Wi-Fi use, subdivided into channels. Three bands are used for Wi-Fi: 2.4 GHz, 5 GHz, and 6 GHz. Band availability and the number of usable channels depend on the regulatory domain.

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Beacon

A frame that an access point radio transmits periodically to advertise a network’s presence and configuration. Beacons carry the same information elements as a probe response and are the basis for passive scanning.

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BSSID

Basic Service Set Identifier. A 48-bit identifier, commonly displayed in MAC-address format, that identifies a basic service set advertised by an access point radio. Multiple BSSIDs may advertise the same SSID.

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Channel

A numbered portion of a Wi-Fi frequency band used for communication. A channel number is meaningful only in the context of its frequency band. Availability depends on the hardware, regulatory domain, and scan source.

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Channel bonding

A technique that combines two or more adjacent 20 MHz channels into a single, wider channel to increase throughput. One of the combined channels is designated the primary channel. See also channel width.

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Channel width

The amount of radio-frequency spectrum occupied by a Wi-Fi channel, expressed in megahertz (MHz). Common Wi-Fi channel widths include 20, 40, 80, 160, and 320 MHz, although availability depends on the band, hardware, regulatory domain, and scan source.

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Client

A device that connects to a Wi-Fi network through an access point, such as a laptop, phone, or IoT device. Also called a station.

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Co-channel contention

Also called co-channel interference (CCI). Degraded performance that occurs when two or more devices share the same channel and must take turns transmitting rather than transmitting at the same time. Co-channel contention is most common in the 2.4 GHz band, which has only three non-overlapping channels.

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Directed scan

A variant of active scanning in which the probe request includes the SSID of a specific network, so only access points advertising that network respond. In WiFi Explorer Pro 3, explanatory text refers to this method as directed scan mode.

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Dwell time

The amount of time a scan source listens on a single channel before moving to the next one when scanning multiple channels. Dwell time affects the trade-off between scan speed and the likelihood of detecting intermittent traffic.

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Frame

A unit of data exchanged at the 802.11 MAC layer between Wi-Fi devices, such as a beacon, probe request, or probe response. Wi-Fi troubleshooting and analysis tools operate on frames rather than the higher-level packets used in most networking discussions.

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Information element

A variable-length field within a beacon or probe response frame that describes a specific capability or configuration detail of a network, such as its supported data rates or security settings. Apps use information elements to build the network details they display.

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Monitor mode

An operating mode for a Wi-Fi adapter in which it passes along all the Wi-Fi frames it receives, rather than only the frames addressed to it. Monitor mode is required for passive scanning and for most packet capture.

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Network

A Wi-Fi service represented in scan results. Depending on the view or grouping mode, a network entry may represent an individual BSSID or may be grouped with related entries. Multiple network entries can share the same SSID. Heuristic groupings do not necessarily establish authoritative physical-device identity.

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Noise

An estimate of background radio-frequency energy measured by the scan source, usually expressed in dBm. Noise measurements and their accuracy depend on the hardware and scan method. A more negative dBm value represents a lower measured noise level.

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OBSS

Overlapping Basic Service Sets. Destructive interference that can occur when two nearby access points bond the same channels but designate a different primary channel, causing both to treat the medium as clear and transmit at the same time. Wider bonded channels are more susceptible to OBSS. See also channel bonding.

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Passive scan

A method of discovering or monitoring Wi-Fi networks by listening for beacon frames and other available 802.11 traffic instead of sending probe requests. Passive scanning typically requires a Wi-Fi adapter or sensor capable of monitor mode. In WiFi Explorer Pro 3, explanatory text refers to this method as passive scan mode. Linux-based sensors may support active scanning, passive scanning, or both. Android-based sensors do not support passive scanning.

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Primary channel

The 20 MHz channel within a bonded, wider channel that devices use to determine whether the medium is clear before transmitting. See channel bonding and OBSS.

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Probe request

A frame a client sends while active scanning to solicit a response from nearby access points. A probe request may target a specific SSID (see directed scan) or request a response from any network in range.

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Probe response

A frame an access point sends in reply to a probe request, containing the same information elements as a beacon.

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Radio

A radio-frequency transceiver within a Wi-Fi device. An access point may contain multiple radios for different frequency bands, and each radio may advertise one or more BSSIDs.

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Regulatory domain

The set of Wi-Fi frequency and power rules enforced by a country or region’s spectrum authority (for example, the FCC in the United States or Ofcom in the United Kingdom). The regulatory domain determines which bands and channels are available for use.

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RSSI

Received Signal Strength Indicator. An estimate of the power of a received signal, commonly displayed in dBm. RSSI measurements are specific to the receiving hardware and should not be treated as precisely comparable across different devices or scan sources. A value closer to 0 dBm represents a stronger received signal.

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Scan source

The hardware or data feed from which an app obtains Wi-Fi scan information. Examples include the Mac’s built-in Wi-Fi adapter, a remote sensor, or an encapsulated capture feed. The scan source affects which bands, channels, measurements, and scan modes are available.

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Sensor

A remote device that scans for Wi-Fi networks or captures Wi-Fi traffic and sends the results to an app for analysis. Sensor capabilities depend on the device, Wi-Fi adapter, operating system, installed utilities, and configuration.

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SNR

Signal-to-noise ratio. The difference, expressed in decibels (dB), between the received signal level and the measured noise level. A higher SNR generally indicates that the signal is easier to distinguish from background noise. SNR is available only when the scan source provides the measurements needed to calculate it.

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SSID

Service Set Identifier. The name of a Wi-Fi network. Multiple access points, radios, or BSSIDs may advertise the same SSID. An SSID is therefore not a unique identifier for an access point or physical device.

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Vendor

The manufacturer of an access point or radio, generally derived from the Organizationally Unique Identifier (OUI) — the first three octets of a BSSID — using a vendor database. Vendor identification is a best-effort lookup and may be unavailable or imprecise if the OUI isn’t registered or is locally administered.