It is not default… Every time you create a BTS, you must choose where and how you carry your RSLs over the Abis. Several possibilities (depending on vendors)
– each RSL gets static 16kbps
– each RSL gets static 32 kbps
– each RSL gets static 64kbps (i think it exists, i’m not sure)
– 4 RSL share 64kbps (dynamic)
– 2 RSL share 64 kbps (dynamic)
Most common conf is the dynamic 4RSL/64kbps
It is just that the 4 RSL of 4 TRXs are multiplexed over a shared capacity of 64kbps.
Each one is not statically allocated 16kbps : the sharing is dynamically computed, depending on needs of each RSL.