We propose a hybrid uplink architecture that seamlessly integrates 802.11 WLAN (ad-hoc mode) and WCDMA interfaces. In our scheme, mobile stations can be dynamically appointed as a Relaying Mobile Terminal (RMT) to forward uplink traffic. The RMT terminals significantly reduce the overall transmission activity and out-of-cell interference to the neighboring cells. To find the close approximation of the optimum RMT set, we propose a 2-approximation-based heuristic algorithm that is originally used to solve a minimum vertex set . The algorithm results in low out-of-cell interference, and the selected RMT terminals have good channel quality with the base stations.