Cwnp Exam Terms

Front 1

Active Mode

Back 1

Power management of a non-AP station (STA) operates in either active mode or powersave mode. Active mode is always in an awake. Vendors have called this, “Continually Aware mode (CAM)” and other similar variations. Wireless STAs that are always powered by AC should be configured for Active Mode.

Front 2

Adjacent Non-overlapping Channel

Back 2

DSSS: Adjacent is any channel with non-overlapping frequencies.
HR/DSSS: Adjacent is any channel with non-overlapping frequencies.

ERP: Adjacent channel is first channel with a non-overlapping frequency space.
OFDM: Adjacent channel is first channel with a non-overlapping frequency space.

Front 3

Adjacent Overlapping Channel

Back 3

DSSS: < 30 MHz
HR/DSSS: < 25 MHz
ERP: < 25 MHz
OFDM: N/A

Front 4

Adjacent Channel Interference

Back 4

A performance condition that occurs when two or more access point radios are providing RF coverage to the same physical area using overlapping frequencies. Simultaneous RF transmissions on overlapping frequencies in the same area can result in corrupted 802.11 frames. Corrupted 802.11 frames cause retransmissions, which results in both throughput degradation and latency.

Front 5

A-MSDU

Back 5

A structure containing multiple MSDUs, transported within single (unfragmented) or multiple (fragmented) Data MPDUs.

Front 6

A-MPDU

Back 6

A structure containing multiple MPDUs, transported as a single PSDU by the PHY.

Front 7

ATIM

Back 7

Announcement Traffic Indication Message

A frame (message) sent between peers in an Ad Hoc network indicating that data is awaiting delivery to the station that receives the ATIM frame from the station that sent the ATIM frame.

Front 8

Autonomous Access Point

Back 8

Contains full MAC layer processing locally within the AP. Sometimes known as a “fat” or “thick” AP, autonomous APs typically have greater memory and processing performance than controller-based APs. Originally autonomous APs required individual management, limiting scalability. Now some autonomous APs are centrally managed via a WNMS.

Front 9

Channel Stacking / Channel Spanning / Channel Blankets

Back 9

When a Single Channel Architecture (SCA) is used, WLANs may be co-located in the same physical area on different 802.11 channels for the purpose of high-density / high-capacity client deployments.

Front 10

Co-channel Interference

Back 10

A performance condition that occurs when two or more independently coordinated access point radios are providing RF coverage to the same physical area using the same 802.11 channel. Additional RF medium contention overhead occurs for all radios using this channel in this physical area resulting in throughput degradation and latency.

Front 11

Controller-based Access Point

Back 11

Also called “lightweight” or “thin”) access point. Used with a controller-based system. Often called a “Split MAC” architecture. Controller-based APs typically have less intelligence or processing capabilities than autonomous APs. The controller houses most of the intelligence in this architecture and is used to centrally control and manage the access points. Allows simplified, centralized management and the control of large groups of access points from a single controller.

Front 12

DSSS

Back 12

Direct Sequence Spread Spectrum (clause 15). This transmission technology is specified in the 802.11-1999 standard and uses 1 and 2 Mbps data rates. 802.11b and 802.11g amendments specify support for DSSS for backbackwards compatibility. The 802.11a amendment does not offer support for DSSS.

Front 13

DSSS-OFDM

Back 13

An optional ERP modulation specified by the 802.11g amendment. A hybrid modulation combining a DSSS preamble and header with an OFDM payload transmission. DSSS-OFDM has payload data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps are defined in 19.7. These are the same rates as ERP-OFDM.

Front 14

DRS

Back 14

Dynamic Rate Switching

Name used in 802.11g, clause 9.6 for multirate support whereby stations may change their data rate (and hence coding and modulation types in use) as they move toward or away from an access point in order to maintain a high quality connection. Previously referred to by vendors as “Automatic Rate Switching (ARS)” or “Dynamic Rate Selection (DRS)”.

Front 15

EEG

Back 15

Enterprise Encryption Gateway

An EEG is a L2 encryption device (similar to VPN) that allows for strong authentication and encryption of data across a wireless medium. The client devices have authentication/encryption software and the EEGs are the encryption termination point in the network. Autonomous access points are placed downstream from the EEGs and may act as an 802.1X authenticator.

Front 16

ERP

Back 16

Extended Rate Physical (clause 19) 802.11g

DBPSK/DQPSK: 1 and 2
CCK: 5.5 and 11
OFDM: 6, 9, 12, 18, 24, 36, 48, and 54

Transmission and reception capability for 1, 2, 5.5, 11, 6, 12, and 24 Mbps data rates is mandatory.

Front 17

ERP-DSSS

Back 17

A required ERP modulation specified by the 802.11g amendment that uses the capabilities of clause 18 (HR/DSSS - 802.11b) with the following exceptions:

1. Support of the short PLCP PPDU header format capability of 18.2.2.2 is mandatory.
2. CCA (see 18.4.8.4) has a mechanism that will detect all mandatory Clause 19 sync symbols.
3. The maximum input signal level (see 18.4.8.2) is -20 dBm.
4. Locking the transmit center frequency and the symbol clock frequency to the same reference oscillator is mandatory.

Front 18

ERP-OFDM

Back 18

A required ERP modulation specified by the 802.11g amendment that uses the capabilities of clause 17 (OFDM - 802.11a) with the following exceptions:
1. The frequency plan is in accordance with 18.4.6.1 and 18.4.6.2 instead of 17.3.8.3.
2. CCA has a mechanism that will detect all mandatory Clause 19 sync symbols.
3. The frequency accuracy (see 17.3.9.4 and 17.3.9.5) is ±25 PPM.
4. The maximum input signal level (see 17.3.10.4) is -20 dBm.
5. The slot time is 20 µs in accordance with 18.3.3, except that an optional 9 µs slot time may be used when the BSS consists of only ERP STAs.
6. SIFS time is 10 µs in accordance with 18.3.3. See 19.3.2.3 for more detail.

Front 19

ERP-PBCC

Back 19

An optional ERP modulation specified by the 802.11g amendment. This is a single-carrier modulation scheme that encodes the payload using a 256-state packet binary convolutional code. These are extensions to the PBCC modulation in Clause 18. ERP-PBCC modes with payload data rates of 22 and 33 Mbps are defined in 19.6.