Video packet multiplexer with intelligent packet discard

Abstract

A IP video delivery system ( 10 ) includes a multiplexer ( 30 ) for transmitting multiple data streams of packets over link ( 31 ) to a site having one or more receivers ( 22 ). During times of congestion, the multiplexer will discard packets from its internal queues. Packets are intelligently chosen to minimize the effects on the output from the receivers ( 22 ) by taking into account timing information related to the packets and priority.

1 . A multiplexer for broadband subscriber access, comprising: 
 a memory queue for storing packets of video information;    traffic management circuitry for selectively discarding one or more packets from the memory queue responsive to a detection of congestion in the memory queue based on parameters associated with existing packets currently in the queue.    
   
   
       2 . The multiplexer of  claim 1  wherein said traffic management circuitry detects congestion where a current transit time through the multiplexer is greater than a time-to-live parameter associated with an incoming packet.  
   
   
       3 . The multiplexer of  claim 2  wherein said time-to-live parameter is determined by observing the arrival of incoming packets.  
   
   
       4 . The multiplexer of  claim 1  wherein the traffic management circuitry detects congestion based on information associated with information on packets to be sent in the future.  
   
   
       5 . The multiplexer of  claim 4  wherein information on packets to be sent in the future comprises header information from packets to be sent in the future.  
   
   
       6 . The multiplexer of  claim 5  wherein said header information is stored in a virtual queue.  
   
   
       7 . The multiplexer of  claim 1  wherein said traffic management circuitry discards packets having interdependencies with previously discarded packets.  
   
   
       8 . The multiplexer of  claim 7  wherein the packets having interdependencies comprises packets containing differential video data.  
   
   
       9 . The multiplexer of  claim 1  wherein said memory queue comprises a plurality of first-in, first-out (FIFO) memories associated with respective data streams, and wherein said traffic management circuitry includes circuitry for discarding low priority packets from any of the FIFO memories responsive to a detection of congestion.  
   
   
       10 . The multiplexer of  claim 9  wherein said traffic management circuitry includes circuitry for discarding high priority packets only from the FIFO memory associated with an incoming packet causing the congestion.  
   
   
       11 . A method of multiplexing packets for broadband subscriber access, comprising the steps of: 
 storing packets of video information in a memory queue;    detecting congestion situations;    selectively discarding one or more packets from the memory queue responsive to a detection of congestion in the memory queue based on parameters associated with existing packets currently in the queue.    
   
   
       12 . The method of  claim 11  wherein said detecting step comprises the step of detecting situations where a current transit time is greater than a time-to-live parameter associated with an incoming packet.  
   
   
       13 . The method of  claim 12  wherein said step of step of detecting situations where a current transit time is greater than a time-to-live parameter associated with an incoming packet comprises the step of observing the arrival of incoming packets to estimate the time-to-live parameter.  
   
   
       14 . The method of  claim 11  wherein the detecting step comprises the step of detecting congestion based on information associated with information on packets to be sent in the future.  
   
   
       15 . The method of  claim 14  wherein said step of detecting congestion based on information associated with information on packets to be sent in the future comprises the step of receiving packets including header information from packets to be sent in the future.  
   
   
       16 . The method of  claim 15  and further comprising the steps of storing the header information in a virtual queue.  
   
   
       17 . The method of  claim 11  wherein said discarding step comprises the step of discarding packets having interdependencies with previously discarded packets.  
   
   
       18 . The method of  claim 17  wherein the packets having interdependencies are packets containing differential video data.  
   
   
       19 . The method of  claim 11  wherein said memory queue comprises a plurality of first-in, first-out (FIFO) memories associated with respective data streams, and wherein said discarding step comprises the step of discarding low priority packets from any of the FIFO memories responsive to a detection of congestion.  
   
   
       20 . The method of  claim 19  wherein said traffic management circuitry further includes circuitry for discarding high priority packets only from a FIFO memory associated with an incoming packet causing the congestion.