【作者】 张浩；

【导师】 尹逊和；

【作者基本信息】 北京交通大学 ， 控制理论与控制工程， 2011， 硕士

【摘要】 Ad Hoc网络无需固定基础设施的支持,具有组网方便快捷、可靠性高、灵活性强等优点。Ad Hoc网络作为移动通信新崛起的一个重要分支,从最初的军事应用逐渐渗透到民用领域,在最近十几年得到了快速发展。由于网络中的节点一般是由有限能量的电池供电的,Ad Hoc网络面临生存时间、吞吐量、网络容量以及时延等方面的挑战,因此功率控制成为Ad Hoc网络研究中的一个重要方向。本文从控制理论的角度出发,分析了Ad Hoc网络中的功率控制问题,利用控制理论的方法来解决MAC层发射功率的动态调节问题。本文围绕Ad Hoc网络的实际应用,首先介绍了Ad Hoc网络的发展历史、体系结构及未来的应用前景,然后分别从通信技术和控制理论角度介绍了解决功率控制问题的思路及其优缺点。接下来总结了Ad Hoc网络功率控制性能的评价指标,并用这些指标对几个功率控制方法的性能进行了评价。随后介绍了基于发射探测信号的信道探测方法,该方法可以通过发射功率信号对信道状况做出及时、准确的探测。基于多控制器自适应切换方法在功率控制中的应用,提出了将信道探测与多控制器自适应切换功率控制相结合的方法：多控制器切换方法利用信道探测对时变的网络环境准确感知,可以使发射功率更快收敛到最优值,同时改善了网络其它方面的性能。为了防止控制器切换时刻控制器输出的扰动对系统稳定性造成影响,加入基于快慢分解的无扰切换方法,消除了切换时刻的控制器输出不连续和尖峰现象,改善了控制器在切换时刻不利的瞬态响应。最后,为了验证该方法在真实网络中的性能,采用接近网络实际环境的仿真软件NS2进行了仿真研究。仿真结果表明,多控制器切换功率控制方法加入信道探测后,发射功率收敛速度加快,从而使网络的整体性能得到了增强。更多还原

【Abstract】 ABSTRACT:Ad Hoc wireless network is characterized by the facts that they are capable of operating without the support of any fixed infrastructure and they can be setup quickly and flexibly. As a new branch of the wireless communication technologies, Ad Hoc network has been developed rapidly and widely used in both military and civil applications. As the network nodes are generally limited by the energy of the battery power, Ad Hoc networks are facing challenges such as lifetime, throughput, network capacity, delay and so on. Therefore, power control in Ad Hoc Networks is an important direction. In this research, power control problems of Ad Hoc networks are discussed from the view of control theory, and control theory methods are used to solve the problem of MAC (Medium Access Control) layer transmitter power dynamic adjustment.Focusing on the practical application of Ad Hoc networks, Ad Hoc Network development history, architecture and future applications are introduced. The power control schemes based on the communication technology and control theory are introduced, and their advantages and disadvantages are discussed, too. Then, the Ad Hoc network performance evaluation indices of power control are summarized, and the performance of several power control methods are evaluated by these performance evaluation indices. A channel probing approach is introduced, which can make fast and accurate estimation by transmitting power signals. Based on multiple controllers adaptive switching control method utilized in wireless network power control, a combination method of channel probing and multiple controllers adaptive switching method is proposed. Multiple controllers switching method with channel probing using accurate information of time-varying network environment, transmitter power can quickly converge to the optimal value, while improving other aspects of network performance. In order to prevent the disturbance of controller output from affecting the stability of the system when the controllers switch, a bumpless transfer method based on slow-fast decomposition is introduced to improve the transient response of the system.Finally, to verify the performance the algorithm above in a real network, a simulation software named NS2 which can simulate the real network is used. Simulation results show that adding channel probing to multiple controllers switching can make the transmitter power convergence faster, thus the overall network performance can be increased.更多还原