Hello est, Albert, and all,
I read a paper, 'Picasso: Flexible RF and Spectrum Slicing', from SIGCOMM 2012 recently. And I found it gives a solution to integrate many spectrum bands into one antenna and RF chain.
Basically, Picasso uses a very wideband AD/DA and then digitally slices the spectrum into many bands for different usages. There are some tricks for interference cancellation.
I'm not a RF expert. I don't know whether this solution is really novel. I just remember that you mentioned that LTE has a too wide frequency range and this brings big challenge to mobile chipset design. Picasso is a possible solution to this problem.
Just FYI
Lin