Many studies show that the wireless network interface (WNI) accounts for a significant part of the power consumed by mobile terminals. Thus, putting the WNI into sleep when it is idle is an effective technique to save power. To support streaming applications, existing techniques cannot put the WNI into sleep due to strict delay requirements. In this paper, we present a novel power-aware and QoS-aware service model over wireless networks. In the proposed model, mobile terminals use proxies to buffer data so that the WNIs can sleep for a long time period. To achieve power-aware communication while satisfying the delay requirement of each flow, a scheduling scheme, called priority-based bulk scheduling (PBS), is designed to decide which flow should be served at which time. Through analysis, we prove that the PBS service model can provide delay assurance and achieve power efficiency. We use Audio-on-Demand and Web access as case studies to evaluate the performance of the PBS service model. Experimental results show that PBS achieves excellent QoS provision for each flow and significantly reduces the power consumption.