N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 7 - LAN, WAN, VPN, WLAN, MAN, FDDI and Optical MANS                                                     Slide 45 of 45 _________________                                                                                  __________

Glossary

ATM - Asynchronous Transfer Mode is a cell-based connection-orientated data service offering high-speed data transfer.

Baseband - A signal that has not undergone any shift in frequency. It is purely a digital signal .

Broadband - A signal that has undergone a shift in frequency. A broadband signal is analog. 

BPSK - Binary Phase Shift Keying, a modulation technique for data transmission.

CCK - Complementary Code Keying, a modulation technique that the IEEE 802.11b standard specifies for delivery of 5.5 M bps and 11 M bps..

CSMA/CD - A LAN control technique where all devices in the LAN listen for transmission in progress before they begin to transmit. If two or more attempt to transmit at the same time, each will back off for a variable period of time as determined by a predefined algorithm.

DQPSK - Differential Quadrature Phase Shift Keying, a modulation technique for data transmission.

DSSS - Direct Sequence Spread Spectrum combines a data signal at the sending station with a higher data-rate bit sequence. A DSSS signal is resistant to interference.

DBPSK - Differential Binary Phase Shift Keying, a modulation technique for data transmission.

FDDI - Fiber Distributed Data Interface, a high speed networking technology.

FHSS - Frequency Hopping Spread Spectrum, a technique which takes the data signal and modulates it with a carrier signal that hops from frequency to frequency as a function of time over a wide band of frequencies. To receive the signal, the receiver must be set to the same hopping code and listen to the incoming signal at the right time at the correct frequency.  

IP - Internet protocol.

MAN - Metropolitan Area Network, a high-speed network that covers many kilometers.

MON - Metropolitan area Optical Network, a high-speed network using DWDM and SONET/SDH technologies.

MPLS - MPLS stands for Multiprotocol Label Switching.   In an MPLS network, incoming packets are assigned a "label" by a label edge router.  Packets are forwarded along a label switch path where each label switch router makes forwarding decisions based solely on the contents of the label.  At each hop, the lable switch router strips off the existing label and applies a new label which tells the next hop how to forward the packet.

OFDM - Orthogonal Frequency-Division Multiplexing, A modulation technique that divides a high-speed information signal into multiple lower-speed signals that are transmitted simultaneously at different frequencies in parallel. This technique is used by the IEEE 802.11a standard. 

POP - Point of Presence, refers normally to the locations where an ISP offers access to its network.

QAM - Quadrature Amplitude Modulation, a modulation technique used for data transmission.

QPSK - Quadrature Phase Shift Keying, a modulation technique used for data transmission.

STP - Shielded Twisted Pair, defined by IBM Cabling System for wiring a building.

SONET - Synchronous Optical Network technology defines an interface option for high-speed devices, like ATM switches.

Token Passing LANs - Uses a token to manage the data transmission from workstations connected to it. 

UTP - Unshielded Twisted Pair, a popular type of cable used for LANs and in buildings for voice and data communications.