An ad-hoc network is a collection of wireless mobile nodes without the required intervention of any centralized Access Point. With the existence of the hidden terminals and the absence of the central control, the resource allocation is always a very challenging problem in such networks. In this paper, a distributed resource allocation scheme is designed for ad hoc networks, in which each mobile node dynamically searches its Native Index (NI) with negligible communication overhead. By utilizing the NI, the hidden terminal problem can be completely avoided in the resource allocation, and the resource can be efficiently distributed to all the nodes. The proposed resource allocation method can greatly improve the system throughput. Utilizing the method, the broadcast problem can be easily solved and QoS service (Quality of Service) can be efficiently supported.