Modulation and Coding Terms

• (16-QAM):  16-level quadrature amplitude modulation A modulation technique that sends 16 different signals simultaneously.
• 2X mode: A proprietary transmission scheme to double the effective rate of an 802.11a network.
• (64-QAM):  64-level quadrature amplitude modulation A modulation technique that can transmit 1.125 Mbps over 48 subchannels each.
• Barker code:  The bit pattern used in direct sequence spread spectrum (DSSS) modulation.
• Channel bonding: An 802.11g proprietary technique in which two channels are combined to provide frequency for higher speeds.
• Chipping code:  The bit pattern used in direct sequence spread spectrum (DSSS) modulation.
• (CCK):  Complementary code keying A coding technique used in 802.11b networks that consists of a set of 64 8-bit code words.
• (DBPSK) :   Differential binary phase shift keying two-level phase shift key used in 802.11b networks.
• (DQPSK):  Differential quadrature phase shift keying A four-level phase change used in 802.11b networks.
• (DSSS):  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 occurs on a specific frequency in a frequency hopping spread spectrum (FHSS) transmission.
• Dynamic turbo:  An 802.11g proprietary technique that automatically checks for available frequencies before implementing channel bonding.
• (FEC):  Forward Error Correction An IEEE 802.11a error correction technique that transmits a secondary copy along with the primary information.
• (FHSS):  Frequency hopping spread spectrum A modulation technique that uses a range of frequencies that change during the transmission.
• Hop time:  The amount of time that a transmission stays on a specific frequency in a frequency hopping spread spectrum (FHSS) transmission.
• (OFDM):  Orthogonal frequency division multiplexing A wireless LAN modulation technology that splits a high-speed digital signal into several slower signals running in parallel.
• PBCC-22  (Packet Binary Convolution Coding): An optional 802.11g technique for transmitting at 22 Mbps.
• (PLCP):  Physical Layer Convergence Procedure A Physical layer sublayer that reformats the data received from the MAC layer (when transmitting) into a frame that the PMD sublayer can transmit and “listens” to the medium to determine when the data can be sent.
• (PMD):  Physical Medium Dependent 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.
• (QPSK):  Quadrature phase shift keying An IEEE 802.11a modulation technique that increases the amount of data encoded to 250 Kbps per channel.
• (SWAP):  Shared Wireless Access Protocol A protocol that defines a set of specifications for wireless data and voice communications around the home; no longer widely used.