LTE doesn't work like that!
Having a bunch of OFDM (whether LTE or WiMax) femtocells is a terrible idea!
OFDM uses a bunch of narrow band carriers for data transport. These carriers must be allocated between transmitting sites so as not to have interference among the different transmitters, be those transmitters the base station, femtocell, or mobile. The carrier allocation needs to be under the control of the area SoftBank (for example) infrastructure - that means much more control channel traffic to/from the femtocells, base stations, and mobiles, and extra computing power for the allocation algorithm to deal with the new femtocells!
This could all go horribly wrong. With cdma it works easily, with OFDM, NOT!