In this paper, we consider TCP-based applications over a high bandwidth wireless channel, such as the High-Speed Downlink Packet Access (HSDPA) channel in aWCDMAsystem, in two setups: a nominal one that employs end-to-end TCPReno and a new one that employs Cross-Layer Adaptation (CLA) in the form of Radio Network Feedback (RNF). For theCLAsetup, the Radio Resource Management unit in the Radio Network Controller (RNC) provides a proxy with reports on the radio link bandwidth and the queue level. The proxy transport layer takes appropriate actions on these reports. By doing so, it utilizes the air-interface spectrum more efficiently and keeps the layer-2 queue in the RNCclose a predetermined level. These new control mechanisms are evaluated through ns-2 simulations. In a number of realistic use cases it is shown that the new CLAsetup reduces the time to serve users, and substantially increases the radio link utilization and decreases the required buffer size in the RNC.