MULTI-NODAL DIGITAL TELEPHONE DISTRIBUTION SYSTEM

摘要

A Cabin Distribution System (CDS) provides the necessary interfaces between each of the telephone units used by the passengers on the airplane and a Cabin Telephony Unit (CTU). The CTU is an intelligent telephony switch that controls and routes telephone calls between the passengers and a plurality of communication networks. A primary rate interface such as a CEPT E1 interface is used to connect the plurality of telephone units to the CTU in a loop-based configuration. The E1 interface provides thirty-two communication channels. Preferably, a link access protocol over the D-Channel is utilized to control the communications on the E1 interface. Utilizing the LAP-D protocol, of the thirty-two channels available on the E1 interface, a first channel is used for framing the communication messages, and a sixteenth channel, referred to as the D-Channel, is utilized as the data communication channel. Advantageously, the remaining thirty channels, which are referred to as B-Channels, are available to connect telephone calls. Data information transferred on the DChannel is interrupted by each telephony group for a delay of sixteen frames to determine if the data is intended for the group. Voice information that is transmitted along the B-Channels is only interrupted for one frame by each group to determine if the data is intended for the group. By preventing the groups of telephones from interrupting the transmissions on the B-Channel for an extended length of time, unnecessary and unwanted delays in the voice communication are eliminated.