Your UE still has only 2 Tx chains.
So how can 5.5G give it access to 4 uplink bands?
Wait… this is where FSA gets interesting 
With the basic SUL model:
• 2 UL bands configured
• band changes rely on RRC → seconds
With FSA:
• up to 4 UL bands configured
• only 1 or 2 transmit at any instant
• the gNB selects the best carrier or pair via DCI → milliseconds
Based on what?
Real traffic capacity per band, TDD slot configuration and channel conditions.
So no, the UE didn’t suddenly gain 2 extra Tx chains 
The network simply gets more UL choices and can switch at TTI level to use the best opportunity. Fast.
Same 2 Tx.
4 configured bands.
Max 2 active.
Much smarter uplink.
That’s one of the mechanisms helping 5G-Advanced move towards 1 Gbit/s UL.
The trap?
4 configured ≠4 transmitting.
Many people miss this detail.
Would you know how to validate it from UE logs?
Follow me for more 5G/5.5G explained from the field, not just slides.
LinkedIn: