(sel´ū-l&r) (adj.) Refers to communications systems, especially the Advance Mobile Phone Service (AMPS), that divide a geographic region into sections, called cells. The purpose of this division is to make the most use out of a limited number of transmission frequencies. Each connection, or conversation, requires its own dedicated frequency, and the total number of available frequencies is about 1,000. To support more than 1,000 simultaneous conversations, cellular systems allocate a set number of frequencies for each cell. Two cells can use the same frequency for different conversations so long as the cells are not adjacent to each other.
For digital communications, several competing cellular systems exist, including GSM and CDMA.
- center channel
In a surround sound system the center channel refers to the channel which produces the audio which should come from directly in front of the viewer from a center front location.
- central tunneling
In VPN technology, central tunneling is the process of forcing all traffic from a remote VPN through a central site. Central tunneling allows additional security as remote VPN users are protected by a firewall at the central site, and also enables NAT, IDS, IPS and anti-virus and spam filtering. Central tunneling does increase bandwidth at […]
- centralized network
A type of network where all users connect to a central server, which is the acting agent for all communications. This server would store both the communications and the user account information. Most public instant messaging platforms use a centralized network. Also called centralized server-structure.
Short for central office exchange service, a type of PBX service in which switching occurs at a local telephone station instead of at the company premises. Typically, the telephone company owns and manages all the communications equipment necessary to implement the PBX and then sells various services to the company.
In computer-based training (CBT) also called computer-assisted instruction (CAI), certification refers to both the program and the process a student must go through to obtain certification in the studied area. Certification also includes testing and assessment that must be met by the learner with a minimum acceptable score.