中文摘要：

定向天线能显著提高无线系统的性能和容量,但采用定向天线的自组网拓扑构建问题比全向天线网络复杂.拓扑控制是一种保证网络连通和节能的有效手段.文中通过对随机波束自组网连通问题定性和定量的分析研究,运用样方统计法推导保证拓扑图高概率连通的临界邻居数;在此基础上,提出了一种基于邻居数的分布式拓扑控制协议,节点独立确定天线波束的朝向和信号发送功率大小,使得天线覆盖邻居节点个数等于（或略小于）预先设定的临界邻居数.该协议的特点是获取邻居信息的代价小,且运行简单.仿真结果表明：新协议在维护网络高概率连通的同时保证了节点最小能量特性;在节点能耗和网络传输性能等方面均优于全向天线基于邻居数的拓扑控制协议.

英文摘要：

Directional antennas have received considerable attention in the last few years due to the spatial-reuse they provide which increases the potential capacity of wireless networks.But the topological connectivity of beamforming antennas in multi-hop wireless networks is more complicated than topologies for wireless networks with omni-directional antennas.Topology control aims to maintain network connectivity and reduce energy consumption for Ad hoc networks using directional antennas.In this paper,the authors employ quadrat statistical methods to derive analytical expressions to determine the critical neighbor number for randomized beamforming network model.A distributed neighbor-based topology control protocol,referred to as the RBNTC,is proposed to maintain the outdegree of every node equal to or slightly below a specific value K.The protocol exchanges exactly bound messages;another positive feature is that it is based on distance estimation only,which can be implemented at a reasonable cost.Extensive simulations are carried out,which show that the RBNTC is to achieve a high probability（more than 99%） of connectivity while constructing a wireless network topology with minimum-energy property.Simulation results show that the proposed protocol achieves considerably better performance than the topology control protocol K-Neigh based on omni-directional antennas in terms of power efficiency and traffic carrying capacity of the network.