, that carries the full destination address used for routing. Glossary dB (decibel) dB (decibel) A unit for measuring the relative strength of a signal parameter such as power or voltage. The number of decibels is 10 times the logarithm (base 10) of the ratio of the power of two signals, or the ratio of the power of one signal to a reference level. DBPSK (Differential Binary PSK) A form of phase-shift keying used for digital transmis- sion in which the phase of the carrier is discretely varied in relation to the phase of the immedi- ately preceding signal element and in accordance with the data being transmitted. The demodulator determines the changes in the phase of the received signal rather than the phase itself. DBPSK is used in low-speed 802.11 WLANs (operating at 1Mbps). (Direct Broadcast Satellite) A satellite system that can transmit DTV signals directly to individual homes. DCCP (Datagram Congestion Control Protocol) A protocol in the TCP/IP protocol suite that provides congestion control for unreliable data flows. DCCP adds end host congestion control behavior to high-rate UDP streams such as streaming media. DCE (data communications [or channel or circuit-terminating] equipment) Equip- ment that provides an interface between the DTE and the transmission channel (i.e., between the carrier's networks). It establishes, maintains, and terminates a connection between the DTE and the transmission channel and is responsible for ensuring that the signal that comes out of the DTE is compatible with the requirements of the transmission channel. DCLEC (data competitive local exchange carrier) A company that is specifically focused on supporting data services in the local loop (e.g., providers that offer DSL services to end users). DCS (Digital Cellular System) A global system for mobile communications-based PCS networks used outside the United States. (digital cross-connect system) A device that enables the reconfiguration of a digital network in response to congestion or failure in the network, as well as on-dem