Some mobile devices are beginning to support both celluar and IEEE 802.11 based network interfaces. Although rates are increasing, current cellular networks provide relatively low bandwidth that do not meet the QoS requirements of many high-demanding multimedia applications. In this paper, we propose an integrated network architecture that utilizes both wireless interfaces to provide better QoS support by QoS Aware Wireless Bandwidth Aggregation (QAWBA). Via QAWBA, mobile nodes form a mobile ad hoc network (MANET) using their IEEE 802.11 interfaces to share their celluar link capacity. Some mobile nodes act as proxies to contribute their idle celluar links to support a QoS request that may exceed the available bandwidth of any individual mobile node. A k-path proxy discovery algorithm is proposed for fast and efficient proxy discovery. Simulation results show that QAWBA can significantly improve network utilization and the admission rate of QoS requests.