As noted elsewhere in this thread, the properties of wireless networks conflict badly with the design principles of TCP. We have a custom TCP stack that replaces some of the standard TCP algorithms with new ones carefully tuned for mobile broadband. It can act as a transparent proxy, presenting a standard stack towards the internet and a optimized one towards the radio network. The packet stream is still standard TCP though, so no client changes are needed.
The product is deployed in some >10Gbps networks, and shows very impressive gains for real live traffic.
thanks for the explanation :) does your layer only sit between the mobile and the point at which the network becomes a wired connection? like, just the other side of the cell towers?