Abstract: The topology control can improve the performance of ad hoc networks，the topological connectivity of beam forming antennas in multihop wireless networks is more complicated than topologies for wireless networks with omni-directional antennas.This paper proposes a local optimal topology control algorithm for ad hoc networks based on steered beam directional antennas.This kind of algorithm uses the idea of cluster to divide the network into a number of areas which can be overlapped.Through running the local Minimum Spanning Tree（MST） algorithm，the neighbourship of nodes in areas is confirmed.Regulating the transmission power of nodes and changing the directional antenna’s direction，beam width and gain，topology can be built.It reduces the average node degrees and the transmission power，thus energy consumption is reduced，traffic interference is decreased and the network throughput is improved.The result of simulation shows that this algorithm significantly improve the network performance.

Key words: ad hoc networks, topology control, directional antennas, local optimal

摘要： 拓扑控制有助于提高ad hoc网络的性能，采用定向天线的自组网拓扑控制比全向天线网络更为复杂。基于自适应波束定向天线模型提出一种局部区域优化的拓扑控制算法。该算法利用分簇的思想将网络划分为可重叠的多个区域，区域内节点采用最小生成树（MST）的思想确定邻居关系，通过调整节点发射功率，改变天线波束的朝向、宽度和增益来构建拓扑。算法减小了节点的平均度数，降低了节点的发射功率，从而降低节点能耗，减少了节点间干扰，提高了网络吞吐量，仿真结果表明，算法显著提高了网络性能。

关键词: ad hoc网络, 拓扑控制, 定向天线, 区域优化