Modulation : Embedding base signals in high frequency carriers.
Multiplexing : Sending more than one information signal on the same communication
Noise : Disturbance in a communication system.
Photodetector : A device that accepts light as input and produces electric current as output.
Repeater : A device used in microwave radio communication which filters noise from
the incoming signal, amplifies and retransmits the signal to the next station
at the same frequency.
Shielded Twisted Pair (STP) : Shielded pair of wires that are twisted.
Signal : A time varying electrical, optical or electromagnetic quantity representing
information, speech, video, etc.
Transponder : A device inside the satellite that receives uplink signals, filters out noise, amplifies and retransmits at the downlink frequency.
Unipolar : Representation of digital signals using voltages of the same polarity.
Unshielded Twisted Pair (UTP) : Unshielded pair of wires that are twisted.
Wavelength : The physical distance occupied by one cycle of a signal wave while propagating
in free space.
Access links : Communication links that connect the user to the nearest switch.
Asynchronous transfer mode : Mode of information transfer in broadband ISDN.
Base station : A wireless station covering a certain geographical area called
Broadband ISDN : An ISDN designed for very high-speed applications.
Cell : In the context of mobile communication, a cell denotes a small geographical area. In the context of broadband ISDN, cell is a small digital packet that carries information.
Cell switching : A switching technique in which information is cast in the form of small cells and transported over broadband ISDN networks.
Cellular communication : A wireless communication technique in which a large geographical
region is divided into a number of cells that are networked.
Channel : An information pipe with some specified characteristics like bandwidth, capacity, level of attenuation and noise immunity.
Circuit : A two-way link comprising two channels, one in each direction.
Circuit switching : A switching technique in which a dedicated path is established between end points for the entire duration of information transfer.
Common Channel Signalling: Signalling done using a separate channel that is common to many information channels.
Datagram : An independent packet containing complete address information.
Digit processing : Processing of a telephone number at the telephone exchange.
End systems : Equipments at the subscriber premises that connect to a telecommunication network.
Fully connected network : A network in which all communicating entities are directly connected with each other.
Packet switching : A switching technique in which large size data is broken as packets and transferred across networks.
Permanent virtual circuit : A virtual circuit assigned on a long-term basis.
Public switched network : A switched network open to public.
Reassembling : The process of assembling packets or cells to reconstruct the original message at the destination.
Resequencing : The process of arranging the packets in proper order when they arrive out of sequence at the destination.
Signalling : Indicative or control signals exchanged between a subscriber and a switching node or between two switching nodes.
Space division switching : A technique in which a dedicated physical path is established inside a switch.
Subscriber : A user connected to a telecommunication network.
Switch : A device that establishes and releases connections between subscribers.
Switched network : A network in which users are connected to a switching system.
Time division switching: A technique in which a shared common resource is used for transferring information from an inlet to an outlet in a switch.
Transmission links : Communication links that interconnect switching systems.
Virtual circuit : A fixed route for information transfer.
Address resolution : Conversion of one address to another like IP address to machine
address and vice versa.