AAL 1 (cont.)
When transmitting low
& variable bit rate signals, the problem with AAL 1 is
even worse:
payload
h
payload
h
payload
h
Packing delay may be even larger ...
... or transmission efficiency even lower
h
h
h
payload
payload
payload
(8 kb/s speech encoding:
47/1000 = 47 ms)
=> use AAL 2 which offers multiplexing of
different signals into the same ATM cell
payload
payload
payload