ATM transmission system with a variable transmission rate

An asynchronous transfer mode (ATM) variable rate transmission system for performing two-way ATM transmission between a transmitting terminal and a receiving terminal through a transmission line, said system comprising:

• a means for detecting cells discarded in data transmitting between said transmitting terminal and said receiving terminal;
• means for transmitting information of discarded cells detected by said receiving terminal to said transmitting terminal through a receiving line of said transmission line and controlling a number of transmitted cells according to a frequency of the occurrence of said discarded cells,
• wherein said cell discard detecting means comprises:
• a counter means for updating a count using a clock obtained from a cell sending rate and thereby producing a time stamp period signal,
• a buffer means for storing a time stamp and data according to a write clock,
• a time stamp comparing means connected to said buffer means for generating a discard indicating signal by comparing the time stamp period signal with said time stamp read from said buffer means,
• means for stopping a read clock of said buffer means when said discard indicating signal indicates the occurrence of a discard, and
• a controlling means for controlling a restart of the read clock by setting a no-discard signal provided by said discard detecting means to NO when said time stamp period signal reaches a value of said time stamp.

An ATM system for transmitting cell information from a transmitting side to a receiving side through a two-way ATM transmission line, said system comprising:

• a multiplexing means provided in said transmitting side for sending a cell comprising cell sending rate, requested cell sending rate discard, time stamp and data, to said receiving side through said ATM transmission line,
• a demultiplexing means provided in said receiving side for separating cells received from said two-way ATM transmission line,
• cell discard detecting means for detecting a discarded cell from the time stamp for defining the cell sending sequence, and generating discarded cell information,
• means for transmitting the requested cell sending rate determined based on the cell sending rate and discarded cell information,
• cell sending rate determining means for determining a cell sending rate and an encoding rate according to said requested cell sending rate received from said receiving side, and
• a variable rate encoder for encoding data to be sent to said multiplexing means according to said encoding rate.

An asynchronous transfer mode (ATM) transmission system for transmitting cell information from a transmitting side to a receiving side through a two-way ATM transmission line, said system comprising:

• a demultiplexing means provided in said receiving side for isolating cells received from said two-way ATM transmission line,
• cell discard detecting means for detecting a discarded cell from a time stamp for defining a cell sending sequence, and generating discarded cell information,
• a multiplexing means provided in said transmitting side containing a cell of said discarded cell information, said time stamp and data, and sending said cell to said receiving side through said transmission line,
• encoding rate determining means for determining an encoding rate by said discarded cell information received from said receiving side,
• a variable rate encoder for encoding data to be sent to said multiplexing means according to said encoding rate,
• time series processing means for inserting a dummy cell into said discarded cell to absorb a time difference caused by said discarded cell when said cell discard detecting means detects a cell discarded from received data, and
• a variable rate decoder for decoding received data after adjusting said time difference.

A transmitting device for an asynchronous transfer mode (ATM) transmission system, comprising:

• means for detecting cells discarded in a transmitting operation;
• an encoding means for encoding an analog data signal to a digital data signal;
• a multiplexing means for multiplexing digital data, a cell transmission rate, a requested cell transmission rate obtained from said detecting means according to a frequency of occurrence of cell discard, and a time stamp based on a cell format;
• and
• a transmitting means for transmitting multiplexed cells to an ATM transmission network according to a timing signal generated by said cell transmission rate which is determined based on said requested cell transmission rate.

A receiving device for an asynchronous transfer mode (ATM) transmission system, comprising:

• a receiving means for receiving a cell;
• a demultiplexing means for separating said cell into cell sending rate CS, a requested cell transmission sending rate CR, a time stamp TS, and data, according to a cell format of a received cell;
• a buffer means for storing said time stamp TS and data according to a write clock;
• a decoder for reading data from said buffer means and decoding said data by said cell sending rate CS;
• and
• a controlling means for generating said requested cell transmission rate CR to be sent to an opposite terminal based on the frequency of a cell discard detected by determining whether or not said time stamp TS read from said buffer means is a predetermined value.