Speed-limited ip fax method and a method for achieving gateway speed limitation in the ip fax

Abstract

A method for limiting bit rate in IP facsimile, in this method the highest bit rate that the called gateway allows is determined, after the call connection is set up, the called electrograph transmits the digital identification containing the highest facsimile bit rate that the called electrograph provides, the called gateway compares the highest facsimile bit rate that the called electrograph provides with the determined highest bit rate that the called gateway allows, then selects the lower and inserts in the frame and transmits to the calling electrograph, the calling electrograph compares the bit rate with the highest bit rate that the calling electrograph itself provides, the lowest will be the highest bit rate at which message is transmitted, then the message is transmitted, confirmed, then the call connection is released. In this method, when the network becomes bad, the highest facsimile bit rate is limited through gateway to improve quality of pictures. A method for achieving limiting bit rate in IP facsimile by a gateway is also proposed in the present invention.

What is claimed is:  
     
         1 . A method for limiting bit rate in IP facsimile, wherein a message transmitter in a PSTN and a message receiver in the PSTN are connected by Internet, and gateways being provided between the transceivers in the PSTN and Internet to modulate and demodulate data between PSTN and IP data package, 
 a. determining the highest bit rate available for a called gateway;    b. setting up call connection between a calling electrograph and the called electrograph via the PSTN connected by the Internet;    c. the calling electrograph and the called electrograph handshaking to determine the available highest bit rate, wherein the called electrograph sends a digital identification signal frame, in which an information word includes the highest facsimile bit rate provided by the called electrograph, the called gateway taking out the bit rate from the information word after receiving the frame and comparing the bit rate with the determined highest bit rate that the called gateway allows, if the bit rate being higher than the highest bit rate that the called gateway allows then the bit rate being amended to the highest bit rate that the called gateway allows, and if the bit rate being lower than the highest bit rate that the called gateway allows then the frame being transmitted to the calling electrograph;    d. the calling electrograph taking out the bit rate from the information word of the frame after receiving the digital identification signal frame, then comparing the bit rate with the highest bit rate provided by the calling electrograph itself, then taking out the lower and inserting in the digital command signal frame and sending to the called electrograph, and this bit rate being as the highest bit rate at which message is transmitted;    e. the calling electrograph transmitting message to the called electrograph;    f. after the message being transmitted, processing to the operation of confirmation, error-correction, continuous transmission for many pages;    g. releasing the call connection.    
     
     
         2 . A method for limiting bit rate in IP facsimile of  claim 1 , wherein in step a, the highest bit rate that the called gateway allows and the highest bit rate that the calling gateway allows are determined simultaneously; after step c, the calling gateway taking out the bit rate from the information word after receiving the digital identification signal frame and comparing the bit rate with the determined highest bit rate that the calling gateway allows, if the bit rate is higher than the highest bit rate that the calling gateway allows then the bit rate is being amended to the highest bit rate that the calling gateway allows, and if the bit rate is lower than the highest bit rate that the calling gateway allows then the frame is normally transmitted to the calling electrograph.  
     
     
         3 . A method for limiting bit rate in IP facsimile of  claim 1  or  2 , wherein in step a, a man-machine interface is respectively provided at the called gateway and the calling gateway, by which the highest bit rate of the called gateway and the calling gateway can be input and stored in the storages of both the called gateway and the calling gateway; in step c, the called electrograph taking out the bit rate from the storage and comparing with the bit rate in the digital identification signal frame.  
     
     
         4 . A method for limiting bit rate in IP facsimile of  claim 1  or  2 , wherein in step a, a performance monitor is provided respectively at the called gateway and the calling gateway to monitor the jam extent of the network in real time, and the result being reported to a controller prestoring with several predefined threshold bit rates, each of the threshold bit rates corresponding to a jam extent, when the jam extent monitored reaches another threshold bit rate, the controller writing the new threshold bit rate into the storages of both the called gateway and the calling gateway; in step c, the bit rate being taken out from the storage to compare with the bit rate in the digital identification signal frame.  
     
     
         5 . A method for limiting bit rate in IP facsimile of  claim 1  or  2 , wherein step b comprises: the calling electrograph initiating a call, then the calling gateway identifying destination address of this call, and setting up the path to the called gateway to the called electrograph from the called gateway, when the called electrograph receiving the call, a responding tone being transmitted back via the called and calling gateway to indicate a call connection having been set up.  
     
     
         6 . A method for limiting bit rate in IP facsimile of  claim 1  or  2 , wherein in step c, the called electrograph transmitting the digital identification signal frame via the called and the calling gateways to the calling electrograph and transmitting a sign bit and a called user's identification, the called user's identification including an address of called electrograph, a typologic information identifying the state of called electrograph, after the identification being received, the calling electrograph transmitting a delivering user's identification to the called electrograph via the calling and called gateways, the delivering user's identification including the address of the calling electrograph, the typologic information identifying the state of calling electrograph.  
     
     
         7 . A method for limiting bit rate in IP facsimile of  claim 6 , wherein in step c, after the calling electrograph and the called electrograph handshaking upon the called user's identification and the digital identification signal frame, the calling electrograph transmitting a training signal to the called electrograph, and when the bunch being received, the called electrograph comparing the received bunch with the prestored training signal which is the same as that in the calling electrograph, and calculating the BER, comparing it with the predetermined BER standard, if the BER being lower than the BER standard, then message being transmitted, if the BER being higher than the BER standard, the message being not transmitted.  
     
     
         8 . A method for limiting bit rate in IP facsimile of  claim 1  or  2 , wherein in the step f, when one or all pages of the facsimile are transmitted, the calling electrograph transmitting the continuous transmission for many pages, finishing identifier to the called electrograph through the calling, called gateway, after the identifier being received, the called electrograph transmitting the continuous transmission for many pages, finishing confirmation identifier to the calling electrograph via the called, calling gateway.  
     
     
         9 . A method for achieving bit rate limit through gateway, gateways are provided between transceivers in PSTN and Internet to modulate and demodulate data between PSTN and IP data package, 
 a. determining the highest bit rate that the called gateway allows;    b. the calling electrograph and the called electrograph handshaking to determine the available highest bit rate, the called electrograph sending a digital identification signal frame, and the highest facsimile bit rate provided by the called electrograph being packaged in the information word of the digital identification signal frame, the called gateway taking out the bit rate from the information word after receiving the frame and comparing the bit rate with the determined highest bit rate that the called gateway allows, if the bit rate is higher than the highest bit rate that the called gateway allows then the bit rate being amended to the highest bit rate that the called gateway allows, and if the bit rate is lower than the highest bit rate that the called gateway allows then the frame being transmitted to the caller;    c. the calling electrograph taking out the bit rate from the information word of the frame after receiving the digital identification signal frame, then comparing the bit rate with the highest bit rate supported by the calling electrograph itself, then taking out the lower and adding to the digital command signal frame and sending to the called electrograph, and this bit rate being as the highest bit rate at which message is transmitted.    
     
     
         10 . A method for achieving bit rate limit through gateway of  claim 9 , wherein in step a, the highest bit rate that the called gateway allows and the highest bit rate that the calling gateway allows are determined simultaneously; after step c, the calling gateway taking out the bit rate from the information word after receiving the digital identification signal frame and comparing the bit rate with the determined highest bit rate that the calling gateway allows, if the bit rate is higher than the highest bit rate that the calling gateway allows then the bit rate is amended to the highest bit rate that the calling gateway allows, and if the bit rate is lower than the highest bit rate that the calling gateway allows then the frame is transmitted normally to the calling electrograph.