mitted through a circuit. The greater the bandwidth, the more data that can be carried, and in digital facilities, bandwidth is expressed in bits per second. bandwidth efficiency The efficiency with which a radio signal can be encoded and, there- fore, how many bits per second can be carried on one cycle of radio bandwidth. bandwidth exchange An organization or a facility that functions as an exchange where bandwidth is the commodity. Some exchanges bring together buyers and sellers of bandwidth and facilitate contract negotiations and transactions; other exchanges actually switch traffic in real-time based on changes in bandwidth prices throughout the course of the day. bandwidth-on-demand A concept in wide area networking in which the user can access additional WAN bandwidth as the application warrants. It enables users to pay for only the band- width they use, when they use it. Barker Code An 11-bit chipping code. The 1 bits are encoded as a particular sequence of 1s and Os, and the 0 bits are the inverse of that sequence. base station controller An intermediate device in the cellular system that controls a group of base-station transceivers. baseband signaling Transmission of a digital signal without any additional modulation, or conversion. The term is typically used to refer to the pure digital side of a circuit when the other side is broadband, or frequency based, which means that the signal is modulated. batch processing A processing method in which a program or programs process data with little or no operator interaction. baud The signaling rate of a transmission line, which refers to the number of transitions (volt- age or frequency changes) made per second. The term is often confused with the number of bits Glossary Baudot code per second that can be supported. At very low speeds and with modulation schemes, there is 1 bit per baud, so the number of baud can equal the number of bits per second. However, modern devices, using more efficient modulation schemes, carry multiple bits per signal; for example