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Data Multiplexing Technique

IP.com Disclosure Number: IPCOM000050655D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Choquet, M: AUTHOR

Abstract

This is a system for channelizing (i.e., concentrating) several data channels, each operating at a speed multiple of a basic speed, over a single transmission channel fed by a modem operating at a speed selected among a set of predetermined speeds.

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Data Multiplexing Technique

This is a system for channelizing (i.e., concentrating) several data channels, each operating at a speed multiple of a basic speed, over a single transmission channel fed by a modem operating at a speed selected among a set of predetermined speeds.

The channelization here is based on the transmission of fixed length frames divided into slots. For a given configuration of data channels and a given modem speed, the number and length of the slots are fixed, but they will vary from one configuration to another. A channelization box generates frames divided into a number of slots equal to the number of channels to be served. Each slot length is a function of both the modem bit rate and the data rate of the considered channel. The channelization box buffers the data of each channel and puts the data in the related slots. The frames are then sent serially to the modem as normal data from a Data Terminal Equipment (DTE). The sum of the slot lengths will be selected smaller than the frame length. The remaining frame space can be either ignored or filled with bits to be used for synchronization checking purposes.

Assuming a slot length of Ls bits, the slots could be structured according to one of the three following formats: case 1 : 1XXX....X.X ------ (Ls - 1) data bits
case 2 : 01XXX...X.X ------ (Ls - 2) supervisory message
case 3 : 000..01X..X ------ (Ls - M) data bits.

For each channel, an elastic buffer is used. Whenever possible, case 1 i...