One of the challenges in designing modern RFID systems is that when more than one tag exists in an RFID environment, it may occurs collisions so that the whole system becomes inefficient and increases the time for identifying RFID Tags. In order to simultaneously recognize several tags within a reader interrogation zone, an anti-collision algorithm should be applied. In this paper, we present an Anticipative Inquiry Scheme (AIS), which is an enhanced technique based on the query tree protocol, for efficient tag identification. The main idea of the Anticipative Inquiry Scheme is to limit number of collisions on different level of a query tree. When number of collisions reaches a predefined acceptable ratio, it reveals that density in RF field is too high. To avoid sending unnecessary inquiries, the prefix matching will be jumped to next level, alleviating the collision problems. We have implemented the Anticipative Inquiry Scheme along with query tree protocol. The experimental results show that the method of setting frequency bound indeed improves the identification efficiency in high density and randomly deployed RFID systems.