中文摘要：

为了解决移动自组织网络（MANET）中暴露终端导致信道利用率降低的问题,指出暴露终端问题的关键在于局部拓扑,并提出一种基于局部拓扑的并发传输算法.该算法中,暴露终端节点通过局部拓扑判断并发传输是否冲突,并通过同步算法完成并发传输.结合IEEE 802.11的DCF协议和跨层设计的思想,开发了local topologybased-distributed coordination function（LTB-DCF）协议.仿真结果表明,相比DCF协议,LTB-DCF在增加较少额外开销的基础上,显著提高了网络的吞吐量。

英文摘要：

To solve the problem of channel resource wasted by exposed terminals in mobile Ad hoc network, exposed terminals is researched. It is pointed out that the key problem is local network topology. Then a concurrent transmission algorithm based on local topology is proposed. In this algorithm, exposed terminals determines whether conflict happens in concurrent transmission through local network topology and complete concurret transmission by synchronization algorithm. Combined with IEEE 802.11 DCF protocol and cross layer mechanisms, a new protocol local topology based distributed coordination function（LTB-DCF） is developed. Simulation results show that compared with DCF, LTB_ DCF protocol improves the network throughput greatly with moderately low overhead.