CWEng key terms

The total power a radio system effectively radiates in a given direction, found by adding transmitter output power to antenna gain and subtracting cable and connector loss. Regulatory rules cap EIRP per band and channel width.

The weakening of a radio wave as it spreads outward through unobstructed space. It grows with both frequency and distance and represents the best-case signal loss any link budget can assume.

Copies of a transmitted signal arriving at the receiver after reflecting off objects along different paths. Because the copies differ in delay and phase, they can distort the signal, hurt demodulation, and increase retransmissions.

A logarithmic unit of absolute power referenced to one milliwatt. Transmit power, received signal level, and noise floor are all reported in dBm, where 0 dBm equals 1 mW and each 3 dB change doubles or halves power.

A figure describing how strongly an antenna focuses radiated energy in a preferred direction compared with a theoretical isotropic radiator. Higher gain comes from a narrower radiation pattern, not from added transmit power.

The background electromagnetic energy present at a receiver on a given channel, from thermal noise plus other emitters. It marks the level below which a signal cannot be reliably decoded, and it rises as interference increases.

The decibel difference between the received signal level and the noise floor measured at the same point. Cleaner, higher ratios support denser modulation and coding; roughly 25 dB is generally needed for the highest data rates.

An elliptical volume surrounding the direct line between two antennas through which signal energy travels. Obstructions inside the first zone weaken the link, so designs typically aim for about 60 percent clearance.

A running account of every gain and loss between transmitter and receiver, including output power, antenna gain, cable loss, and path loss. It predicts the received signal level and shows whether a link will close.

A number showing how well an antenna and its feed line are impedance matched. Near 1:1 means little reflected energy; higher values mean lost power, reduced range, and possible damage to the radio.

A software-modeled survey that estimates coverage from floor plans, wall attenuation values, and antenna patterns before hardware is installed. Its AP count and placement plan must later be confirmed by on-site measurement.

An on-site survey run after installation to prove that coverage, data rates, roaming behavior, and capacity meet the design goals. It combines walking RF measurements with checks of how real clients behave.

A manual method in which one AP is temporarily mounted and moved among candidate locations while measurements are recorded at each spot. It yields realistic coverage and channel-planning data without a full build-out.

Interference caused by two or more radios using the same channel in overlapping areas. Because 802.11 devices contend for the medium, this sharing cuts throughput and raises delay even when signals are strong.

Interference from transmitters on nearby channels whose energy spills into the channel being used. It is worst when wide channels overlap and on 2.4 GHz, where channel spacing is tighter than the signal itself.

The deliberate assignment of channels and channel widths to APs across a floor plan so that overlapping cells use non-overlapping channels and the reuse distance between same-channel APs stays large.

Sizing the wireless network for the number of clients, their traffic mix, and the throughput each needs. It commonly adds APs for density rather than coverage, and it drives channel width and band choices.

A port-based access control framework in which a client must be authenticated by a central server before network access is granted, with EAP carried to that server through the authenticator. It underlies enterprise WPA2 and WPA3.

An EAP method where both the client and the authentication server prove identity with digital certificates. It is one of the strongest enterprise choices because no password is exchanged, but it requires a certificate infrastructure on clients.

A protocol that network access devices use to pass credentials and accounting records to a central server and receive accept or reject decisions, along with authorization attributes such as VLAN or role assignment.

The password-based key exchange used by WPA3-Personal. It defeats offline dictionary attacks on captured handshakes and gives forward secrecy, replacing the weaker pre-shared key exchange of earlier standards.

The exchange after association in which a station and AP confirm they hold the same credentials and derive fresh session keys for encrypted unicast traffic, while the group key is delivered for broadcast and multicast frames.

A standard amendment that adds integrity protection to management frames such as deauthentication and disassociation. It stops spoofed frames from being used to knock clients off the network or force weaker security.

A monitoring system that watches the air for rogue APs, impersonation attacks, and policy violations, then alerts administrators or automatically contains the offending device by sending targeted deauthentication frames.

Use of a sweeping receiver that plots energy by frequency and time, exposing non-Wi-Fi interferers such as microwave ovens, cordless phones, and cameras that a Wi-Fi frame analyzer cannot identify.

A capture tool that records 802.11 management, control, and data frames with their headers so that association, authentication, roaming, and retransmission problems can be diagnosed frame by frame.

The share of time a channel is busy carrying management, control, and data frames plus retries. It reflects real congestion better than client counts, and high values leave little capacity for new traffic.

The percentage of frames sent more than once because no acknowledgement came back. Elevated retries point to interference, weak signal, or hidden nodes and directly reduce the throughput users experience.

A technique that nudges dual-band clients onto 5 GHz or 6 GHz instead of crowded 2.4 GHz, often by delaying or suppressing probe responses on the lower band until the client shows it can use both.

A standard that lets a client pre-establish security keys with a target AP through a key hierarchy shared among APs, so handoffs finish quickly enough for voice and other latency-sensitive applications.

A client that holds on to its current AP well past the point where a better one is available, so throughput and reliability suffer. It is usually countered with minimum RSSI settings and assisted roaming features.

The 48-bit MAC address identifying one basic service set, normally the radio of a single AP on a single channel. Clients use it to tell apart APs that advertise the same network name.

The time between beacon frames, commonly 100 ms, in which an AP advertises its network name, rates, and capabilities. Shorter intervals speed discovery but consume more airtime and client battery.

The number of beacon intervals between delivery traffic indication messages, which signal sleeping clients that buffered broadcast or multicast traffic is waiting. Larger values save battery but delay time-sensitive multicast delivery.

A management element in which an AP lists nearby APs with their channels and identifiers, letting clients choose a roaming target without scanning every channel. It speeds handoffs and reduces off-channel time.

Orthogonal frequency-division multiple access, introduced with 802.11ax, splits a channel into resource units that can serve several clients in one transmission, which improves efficiency in dense networks carrying small packets.

Multi-user MIMO allows an AP to send to, or receive from, several clients at once using multiple spatial streams and beamforming, raising aggregate throughput when those clients sit in sufficiently different directions.

Control and Provisioning of Wireless Access Points, the protocol pair defined in RFC 5415 and 5416 that carries control messages and, optionally, tunneled client traffic between a wireless controller and thin APs.