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Wireless 5
Chapter 5
| Term | Definition |
|---|---|
| 16-level quadrature amplitude modulation | A modulation technique that sends 16 different signals simultaneously. |
| 2x mode | A proprietary transmission scheme that doubles the effective rate if an 802.11a network |
| 64-level quadrature amplitude modulation | A modulation technique that can transmit 1.125 Mbps over each of 48 subchannels |
| bandwidth | The difference between the upper and lower frequencies |
| barker code | The bit pattern used in direct sequence spread spectrum modulation |
| Channel | A numeric value assigned to a frequency range |
| Chipping Code | THe bit pattern used in direct sequence spread spectrum |
| Colocation | Sharing a frequency band between similar devices |
| communication resilience | Term used to describe transmissions that are less prone to interference |
| Convolutional Coding rate | A type of error-correcting code |
| Differential binary phase shift keying | a two level phase shift key used in 802.11b networks |
| Differential quadrature phase shift keying | A four level phase change used in 802.11b networks |
| Direct sequence spread spectrum | A wireless modulation technique that uses an expanded redundant code to transmit each data bit. |
| Dwell Time | The amount of time that a transmission remains in a specific frequency in FHSS |
| Dynamic Frequency Selection | A technology in which IEEE 802.11n WLANS using 40-mhz channels can automatically move to another channel or switch to 20=mhz operation to minimize interference. |
| Extended rate PHYs (ERP) | A manadory mode for the faster 54 mbps IEEE 802.11g |
| Forward Error Correction (FEC) | An IEEE 802.11a error correction technique that transmits a secondary copy along with the primary information. |
| Frequency hopping spread spectrum (FHSS) | A modulation technique that uses a range of frequencies that change during the transmission |
| Full-Channel FHSS | An FHSS technology in which the devices use a minimum 75 hop channels |
| Guard Interval (GI) | A delay built-in into the receiver to allow to late-arriving symbols |
| High-Rate DSSS | Transmission rates above 2 mbps in IEEE 802.11b |
| hopping code | The sequence of changing frequencies in FHSS |
| hop time | The time it takes to change frequency in FHSS |
| intersymbol interference | Signal interference as a result of multipath transmission |
| microsecond | on millionth of a second |
| milliseconds | One thousandth of a second |
| Modulation and coding scheme (MCS) | A system that assigns a numeric value to each of the 77 possible transmission combinations IEEE 802.11n |
| Multiplexing | The process of sending multiple signals simulanwously |
| Narrowband transmission | Radio signals that are sent on only one radio frequency or a very narrow portion of the frequencies |
| OSI reference model | A seven-layer model that conceptually illustrates the steps of networking |
| Orthogonal Frequency Division Multiplexing | A modulation technique that splits a signal high speed digital signal into several slower signals running in a parallel. |
| PBCC-22 (Packet Binary Convolutional Coding) | An optional 802.11g technique for transmitting at 22 mbps |
| Phased Coexistence Operation | An optional IEEE 802.11n technology that alternates between using 20-mhz and 40-mhz channels |
| Physical Layer Convergence Procedure Procedure (PLCP) | A physical layer sublayer that reformats the data received from MSC layer (when transmitting) into a frame that the PMD sublayer can transmit listens to the medium to determine when the data can be sent |
| Physical Medium Dependant | A physical layer sublayer that defines the standards for both the characteristics of the wireless medium and the method for transmitting and receiving data through that medium |
| primary channel | The first channel of two bonded IEEE 802.11n channels |
| Quadrature phase shift keying | An IEEE 802.11a modulation technique that increases the amount of data encoded to 250 kbps per channel |
| Reduced-channel FHSS | A FHSS technology in which the devices use fewer than 75 hop channels |
| Secondary Channel | The second channel of teo bonded IEEE 802.11n channels |
| Spectral Efficiency | The efficiency of the radio measured in the number of bits per second |
| Spread-spectrum transmission | A technique that takes a narrow, weaker signal and spreads it over a braoder portion of the radio frequency band |
| Symbols | Radio frequency signals |
| Transmit power control | An IEEE 802.11a technology to reduce interference |
| Turbo mode | A proprietary transmission scheme used to double the effective rate of an 802.11a network |
| Variable Guard Interval | An IEEE 802.11n technology that uses a reduced guard interval of 4000 nanoseconds |
| complementary code keying | a coding technique used in 802.11b networks that consists of a set of 64 8-bit code words |
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