Less here than meets the eye.
MOST of what is interesting in LTE-advanced is in the cell tower, NOT in the phone.
This consists of things like better co-ordination between cell towers to balance load, to reduce power so they don't interfere, to co-ordinate frequency usage, basically a bunch of stuff that goes by the name SON (self optimizing network).
The most important aspect of this is to provide better coverage at cell edges, it doesn't do much for performance near the cell center.
Next we have capabilities to use more spectrum. Fine --- for the future. But the spectrum has to be fought over, allocated, and acquired. Until that happens, this particular feature doesn't benefit any phone that has it.
Finally we have the theoretical capability to use more antennas on the phone and at the cell tower. Nice, BUT: a phone could get much of the benefit this offers today by just adding a second transmit and third receive antenna, and using them for diversity. (If you're cheap, hooking them up to a switch-and-stay multiplexer; if you're doing it right hooking them up to a full extra RF path and doing MRC.) This does not require any changes at the cell tower or anything LTE-A related (including an LTE-A chip), but would give real performance improvements. This, IMHO, is a far smarter path for any vendor the next year than "real" LTE-A. That only makes sense when the new spectrum is available and/or enough tower have had their antennas upgraded.
