 
 AAL 1
 When transmitting low
 bit rate signals, AAL 1 has a problem:
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 Either packing delay is large ...
 
 
 
 
  
  
  
  
 ... or transmission efficiency is low (cell is
 nearly empty)
 
  
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 (64 kb/s TDM channel:
 47/8000 = 5.9 ms)
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