WiFi abbreviations
From Teknologisk videncenter
Abbreviations
| Abb. | meaning | Notes |
|---|---|---|
| ASK | Amplitude Shift Keying | Keying 0's and 1's by altering the radio carriers amplitude |
| FSK | Frequency Shift Keying | Keying 0's and 1's by altering the radio carriers frequency |
| PSK | Phase Shift Keying | Keying 0's and 1's by altering the radio carriers phase |
| MPSK | Multiple Phase Shift Keying | Keying more than one bit at a time by using four or more phases |
| IR | Intended Radiator | The active RF transmitter |
| RF | Radio Frequency | Rate of oscillation in the range of around 3 kHz to 300 GHz corresponding to radio waves |
| FSPL | Free Space Path Loss | Loss of amplitude of the signal in free space over distance |
| ISI | Intersymbol Interference | Signal misinterpreted by receiver due to multipath signals out of phase |
| EIRP | Equivalent isotropically radiated power | The highest RF signal strength transmitted from a particular antenna. Often expressed in dBm |
| RSSI | Received Signal Strength Indicator | power level received by the receiver radio in dbm |
| mW | Milli Watt | 0,001 Watt |
| dB | Decibel | Logarithmic unit used to express the ratio between two values. dB = 10 x log10 Ratio1 / Ratio2 |
| dBm | Decibel milliwatt | Decibel relative to 1 mW of power. |
| dBi | Decibel isotropic | Antenna gain compared to a theoretical isotropic antenna |
| dBd | Decibel dipole | Antenna gain compared to a theoretical isotropic antenna. Add 2,14 dB to get dBi |
| SNR | Signal to Noise Ratio | Distance between received signal and noise floor. Expressed in dB |
| DRS | Dynamic Rate Switching | Switching to a higher/lower data rate as the received signal increases/decreases |
| ISM | Industrial Scientific and Medical | 902 - 928 MHz, 2,4 - 2,5 GHz and 5,725 - 5,875 GHz bands |
| UNII | Unlicensed National Information Infrastructure | Three 5 Ghz bands each with 100 MHz bandwidth |
| UNII-1 | UNII-1 (lower band) | 5,150 - 5,250 GHz band ( 4 channels ) |
| UNII-2 | UNII-2 (Middle band) | 5,250 - 5,350 GHz band ( 4 channels ) |
| UNII-2E | UNII-2 Extended | 5,470 - 5,725 GHz band 255 MHz bandwidth ( 11 channels ) |
| UNII-3 | UNII-3 (Upper band) | 5,725 - 5,825 GHz band ( 4 channels ) |
| FHSS | Frequency Hopping Spread Spectrum | Transmitting data in small chunks hopping from frequency to frequency |
| DSSS | Direct Sequence Spread Spectrum | Transmitting data is spread across the range of frequencies of the channel. 11 bit PN |
| GFSK | Gaussian Frequency Shift Keying | FSK modulator using a Gaussian filter to reduce spectral width. |
| PN | Pseudorandom number | Used with DSSS to encode 1 bit to 11 bits to reduce transmission errors. |
| CCK | Complementary Code Keying | Used with HR-DSSS to encode 4 bits data to 8 bits using a 8 bit PN |
| HR-DSSS | High Rate DSSS | Uses CCK encoding to get higher data rate than DSSS |
| DQPSK | Differential Quadrature Phase Shift Keying | Modulation using four phase shifts each representing two bits |
| OFDM | Orthogonal Frequency Division Multiplexing | Popular Spread Spectrum technology transmitting between 52 subcarriers |
| FEC | Forward Error Correction | Allows the receiving system to detect and correct bit errors. |
| WWAN | Wireless Wide Area Network | Wireless Network spanning wide areas for example GSM or LTE |
| WMAN | Wireless Metropolitan Area Network | Wireless Network spanning cities for example WiMax |
| WPAN | Wireless Personal Area Network | Wireless Network spanning small personal areas for example Bluetooth or infrared |
| WLAN | Wireless Local Area Network | Wireless Network spanning buildings/campusses for example WiFi/802.11 |
| IS | Integration Service | The process of transforming the MSDU (802.11) frame to other frame standards. Normally ethernet |
| DS | Distribution System | |
| CAM | Content Addressable Memory | MAC address table in a switch used to process packets based on destination MAC address |
| DSS | Distributed System Services | |
| MSDU | MAC Service Data Unit | Upper layer information in data unit in the body of a 802.11 data frame |
| WDS | Wireless Distribution System | |
| SSID | Service Set Identifier | |
| BSS | Basic Service Set | |
| BSSID | Basic Service Set Identifier | |
| BSA | Basic Service Area | |
| ESS | Extended Service Set | |
| IBSS | Independent Basic Service Set | |
| MBSS | Mesh Basic Service Set | |
| AP | Access point | Gives wireless clients access to the network services. |
| DCF | Distributed Coordination Function | The 802.11 fundamental media access method. |
| PCF | Point Coordination Function | Access Point coordinated media access. |
| HCF | Hybrid Coordination Function | |
| CSMA/CA | Carrier Sense Multiple Access with Collision Avoidance | Wireless media access method principle. |
| IFS | Interframe Space | period of time that exists between transmissions of wireless frames. |
| RIFS | Reduced Interframe Space | Highest priority IFS |
| SIFS | Short Interframe Space | Second highest priority IFS |
| PIFS | PCF Interframe Space | Middle priority IFS |
| DIFS | DCF Interframe Space | Lowest priority IFS |
| AIFS | Arbitration Interframe Space | IFS used by QoS stations |
| EIFS | Extended Interframe Space | IFS used with retransmissions. |
| ACK frame | Acknowledge Frame | Acknowledge the reception of a frame by transmitting an acknowledge frame. |
| RTS | Request To Send | A signal requesting the wireless media. |
| CTS | Clear To Send | A signal after RTS acknowledging permission to transmit. |
| NAV | Network Allocation Vector | A timer initiated by the Duration field in 802.11 frames by stations. It is illegal to transmit in this period. Also known as Virtual Carrier sense. Operates on OSI layer 2. |
| CCA | Clear Channel Assesment | Listening to physical medium if a transmission is in progress. Also known as Physical Carrier Sense. Operates on OSI layer 1. |
| PCF | Point Coordination Function | The AP uses polling to ask the clients if they want media access. DCF and PCF are two different media access methods, which can work together. |
| PC | Polling Coordinator | When the AP actively coordinates PCF it's called a PC |
| CFP | Contention Free Period | When the AP uses PCF it alternates between DCF and PCF. When works in PCF mode during CFP. |
| CP | Contention Period | When an AP works as PC in PCF mode the CP is the period it actively poll the clients |
| EDCA | Enhanced Distributed Channel Access | Extension of DCF using up to eight user priority (UP) levels ginving QoS at the MAC level. |
| UP | User Priority | Used in EDCA to give up to eight UP levels making QoS possible. Identical to 802.3D (CoS) QoS priority |
| HCCA | HCF Controlled Channel Access | |
| TXOP | Transmit Opportunity | When a HCF-compliant contends for the medium it receives an alooted amount of time to send frames called TXOP |