CWSS key terms

Alternating electrical energy in the portion of the electromagnetic spectrum used for wireless communication, typically 3 kHz to 300 GHz, which carries signals through the air between a transmitter and a receiver.

The number of complete cycles of an RF signal that occur each second, measured in hertz; higher frequency means more cycles per second and generally shorter range but greater data capacity.

The physical distance an RF wave travels during one complete cycle, equal to the speed of light divided by frequency; shorter wavelengths mean smaller antennas and less ability to bend around obstacles.

The strength or height of an RF wave, representing signal power; it is commonly expressed in decibels relative to a reference and directly affects how far a signal can be received.

A logarithmic unit used to express ratios of power or signal strength; a 3 dB change represents roughly doubling or halving power, and 10 dB represents a tenfold change.

An absolute power measurement referenced to one milliwatt, widely used for WLAN transmit power and received signal strength; 0 dBm equals 1 mW and 20 dBm equals 100 mW.

A defined range of frequencies allocated for a particular type of service, such as 2.4 GHz, 5 GHz, or 6 GHz for Wi-Fi, each with different regulatory limits and propagation behavior.

A specific slice of spectrum within a band used to carry one transmission; channels must be separated enough to avoid overlap, and width affects throughput and interference susceptibility.

The amount of spectrum a single channel occupies, such as 20, 40, 80, or 160 MHz; wider channels carry more data but consume more spectrum and are more prone to interference.

The process of encoding digital data onto an RF carrier by varying its amplitude, phase, or both; more complex schemes carry more bits per symbol but require stronger, cleaner signals.

Quadrature amplitude modulation, a family of schemes that combine amplitude and phase shifts to encode multiple bits per symbol, such as 64-QAM or 1024-QAM used in modern Wi-Fi.

The difference between received signal strength and the background noise level at a receiver; higher SNR allows more complex modulation and therefore higher throughput with fewer retransmissions.

The ambient level of unwanted RF energy at a location, measured in dBm; a lower noise floor improves SNR and is often achieved by removing interfering devices and sources.

Unwanted RF energy that degrades a wanted signal, arising either from other wireless devices sharing the spectrum or from non-communication emitters such as microwave ovens and motors.

Degradation caused when multiple access points or devices transmit on the same channel within range of each other, forcing them to contend for airtime and reducing overall capacity.

Energy from a transmission on a nearby but non-overlapping channel that leaks into the wanted channel, typically caused by poor filtering or improperly spaced channel assignments.

A relative, vendor-specific metric reported by a client or access point indicating how strongly a signal is being received, used for roaming decisions and coverage validation.

The measure of how much an antenna focuses energy in a particular direction compared with an isotropic radiator, expressed in dBi; higher gain narrows coverage angles rather than adding power.

The total power radiated in the strongest direction, calculated from transmitter output plus antenna gain minus cable loss; regulatory bodies cap EIRP for each band and channel width.

An ellipsoidal volume around the direct line-of-sight path between two antennas; obstruction of this zone causes signal loss even when a visual line of sight appears clear.

The reduction in signal strength as a wave travels through free space and interacts with materials; it increases with distance and frequency and is worse through walls, metal, and water.

The arrival of a transmitted signal at a receiver via several reflected paths at slightly different times, which can cause fading and intersymbol interference but also enables MIMO operation.

Multiple-input multiple-output technology that uses several transmit and receive antennas to send parallel data streams or improve reliability through spatial multiplexing and diversity.

An independent data path transmitted between antenna pairs in a MIMO system; each additional stream raises throughput, and the number supported depends on client and AP radio design.

The theoretical speed at which data is carried over a wireless link, determined by channel width, modulation, coding, and number of spatial streams; actual throughput is always lower.

The actual amount of useful data delivered over a link per unit time after accounting for protocol overhead, contention, retransmissions, and interference; always below the nominal data rate.

The share of time a radio spends transmitting on a channel, including management, control, and retransmitted frames; high airtime utilization indicates a congested or inefficient cell.

The percentage of time a channel is sensed busy by a radio, combining useful traffic, management overhead, retransmissions, and interference from neighboring devices.

Carrier sense multiple access with collision avoidance, the contention method used by Wi-Fi in which stations listen before transmitting and use random backoff timers to reduce collisions.

A condition where two clients can reach the access point but not each other, so their transmissions collide undetected; request-to-send/clear-to-send exchanges can mitigate it.

The human-readable name that identifies a wireless network; clients use it to select and associate with the correct network, and it may be hidden but is still discoverable.

The basic service set identifier, usually the MAC address of an access point radio, which uniquely identifies one specific cell rather than the network name shared across many APs.

The process by which a client leaves one access point and joins another with the same network name while maintaining its session, ideally fast enough to avoid noticeable interruption.

Assigning the same channel to access points that are physically far enough apart that their coverage areas do not overlap significantly, maximizing capacity across a deployment.

A documented assignment of channels and transmit power levels to access points across a site, designed to limit co-channel and adjacent channel interference while meeting coverage needs.

A structured assessment of RF conditions at a location, performed before or after installation, to determine access point placement, channel settings, and whether coverage and capacity goals are met.

The geographic area in which a wireless network provides an acceptable signal level and performance, typically defined by a minimum RSSI or data rate target for intended applications.

The total amount of traffic a wireless network can carry in an area, determined by the number of access points, channel availability, airtime, and client density rather than signal strength alone.

A centralized device that configures, monitors, and manages many lightweight access points, handling policies, roaming assistance, RF optimization, and firmware from a single point.

A device that bridges wireless clients onto a wired network, providing the radio interface, authentication, encryption, and coordination of client associations within its coverage area.

A technology that delivers both data and electrical power over a single Ethernet cable to devices such as access points and cameras, simplifying installation where power outlets are unavailable.

A passive component that converts electrical signals into radiated RF energy and back; its type, orientation, and gain determine coverage shape and polarization characteristics.

The orientation of an RF wave's electric field, usually vertical or horizontal; mismatched polarization between transmitter and receiver antennas causes significant signal loss.

A country or region setting that determines which channels, transmit power limits, and features a radio may legally use, often enforced by the access point based on configured country code.

The current Wi-Fi security certification, offering stronger encryption, protection against offline password guessing, and improved handshake security compared with earlier WPA versions.

An IEEE standard for port-based network access control that authenticates users or devices through a supplicant, authenticator, and authentication server before granting network access.

A protocol and server used to centralize authentication, authorization, and accounting for network access, commonly paired with 802.1X to validate enterprise wireless users and devices.

A monitoring system that detects and can automatically respond to rogue access points, unauthorized clients, and wireless attacks by scanning the RF environment continuously.

An unauthorized access point connected to an organization's network or operating nearby, which can bypass security controls and expose the wired network to unauthorized users.

A clear, unobstructed straight path between transmitter and receiver antennas, required for long-distance links and ideally paired with clearance of the first Fresnel zone.