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A contention-based beaconless geographic routing (CBGR) protocol for mobile ad hoc networks is proposed, which includes a basic mode and an optional mode. In the basic mode, when receiving a data packet from upstream node, intermediate nodes in the forwarding area contend to relay it by waiting a dynamic forwarding delay (DFD), which is computed based on its relative position with the upstream node and destination node. The intermediate node with minimum DFD transmits the data packet first and other nodes cancel their scheduled transmission for the same data packet by overhearing its packet forwarding. In the optional mode, upstream node can send data packets to its specified downstream node as long as the communication link between them is valid. An accurate link forecast scheme is used to calculate the valid time based on location and mobility information of upstream node and downstream node. In addition, a one-hop flooding method is introduced to overcome communication void problem. Finally, simulation results show that the CBGR protocol outperforms the LAR1 and BLR protocols in terms of end-to-end delay and packet delivery ratio.