Method of dynamically adapting the size of a jitter buffer

Abstract

The present invention relates to a receiver system in a communication system supporting packet-based communicatior (e.g., an IP-network), including a receiver, speech decoder ( 40 ) and a jitter buffer ( 20 ) for handling delay variations in the reception of a speech signal consisting of packets containing frames with encoded speech. A jitter buffer controller ( 50 ) is provided for keeping information about the functional size of the jitter buffer ( 20 ) and for providing the speech decoder ( 40 ) with control information, such that the speech decoder ( 40 ), based on that information. provides a dynamic adaptation of the size of the jitter buffer ( 20 ) using the received encoded, packetized speech signal. The invention also relates to a method of adapting the functional size of the jitter buffer of a receiver system.

1 - 19 . (canceled)  
   
   
       20 . A method of dynamically adapting the size of a jitter buffer in a receiving system within a communication system supporting a packet-based communication, comprising the steps of: 
 receiving by the receiver system, a signal encoded in packets;    storing the packets in the jitter buffer;    fetching packets from the jitter buffer by a decoder;    decoding the packets in the decoder;    sending information about the received signal from the jitter buffer and the decoder to a jitter buffer controller;    using information about the received signal to determine by the jitter buffer controller, whether the size of the jitter buffer needs to be adapted; and    responsive to the determination, adapting the size of the jitter buffer by extending or compressing the received signal in time by controlling the number of samples the frames stored in the jitter buffer would represent when decoded.    
   
   
       21 . The method of  claim 20 , wherein the step of extending or compressing the signal further comprises increasing or decreasing the rate at which the decoder fetches packets from the jitter buffer.  
   
   
       22 . The method of  claim 20 , wherein the step of adapting the size of the jitter buffer further comprises adding or removing a sample when a packet is decoded in the decoder.  
   
   
       23 . The method of  claim 20 , wherein the step of adapting the size of the jitter buffer further comprises the steps of: 
 adding one or more pitch periods upon decoding in the decoder if the size of the jitter buffer needs to be increased; or    removing one or more pitch periods in the decoder, if the size of the jitter buffer needs to be reduced.    
   
   
       24 . The method of  claim 20 , wherein the step of adapting the size of the jitter buffer further comprises adding one or more frames to a packet or removing one or more frames from a packet.  
   
   
       25 . The method of  claim 20 , wherein the step of using information about the received signal to determine whether the size of the jitter buffer needs to be adapted includes determining a time difference between an arrival time of a packet to the jitter buffer and a time at which the packet is fetched by the decoder.  
   
   
       26 . The method of  claim 20 , wherein the step of decoding further comprises using a CELP-decoder for adaptation control.  
   
   
       27 . The method of  claim 20 , wherein the step of adapting the size of the jitter buffer by extending or compressing further comprises the steps of: 
 performing an LPC-analysis; and    performing an LPC-synthesis.    
   
   
       28 - 29 . (canceled)  
   
   
       30 . The method of  claim 20 , wherein the step of using information about the received signal to determine whether the size of the jitter buffer needs to be adapted includes the steps of: 
 determining whether a probability of packet loss exceeds a maximum threshold value; and    increasing the size of the jitter buffer if the probability of packet loss exceeds the maximum threshold value and the current size of the jitter buffer is less than a maximum allowable size.    
   
   
       31 . The method of  claim 20 , wherein the step of using information about the received signal to determine whether the size of the jitter buffer needs to be adapted includes the steps of: 
 determining whether a probability of packet loss exceeds a maximum threshold value; and    increasing the size of the jitter buffer if the probability of packet loss is less than the maximum threshold value and the current size of the jitter buffer is greater than a minimum allowable size.