【作者】 万佑红；

【导师】 王锁萍；

【作者基本信息】 南京邮电大学 ， 通信与信息系统， 2010， 博士

【摘要】 随着无线网络的发展,用户对通信质量的要求越来越高。跳频、功率控制等链路传输控制技术可以提高无线网络的通信质量,达到扩容的目的。网络拓扑辨识对于提高多媒体业务流在Ad hoc网络中的传输质量具有重要的意义。课题基于状态反馈控制方法,从控制理论的角度,为跳频传输、功率控制及网络拓扑辨识等方面提供了新的思路和方法。论文首先研究了基于混沌和状态反馈控制的跳频传输技术,针对混沌跳频序列在硬件实现中会产生有限精度效应的问题,基于DSP提出了一种混沌序列非周期自扰动方法以克服有限精度效应。针对混沌跳频同步,提出了一种新的非线性反馈函数和基于遗传算法的非线性反馈控制方法,实现了Logistic映射混沌序列在不同参数空间下的同步。通过实验和性能分析证明了所提出方法的有效性。其次,论文综合考虑实际无线CDMA系统中的闭环功率控制回路可能存在的各种干扰、噪声及路径时延的影响,提出了基于时延和扰动的状态空间(DISS)模型。在此基础上,提出了基于时延和扰动补偿的最优功率控制(OPC_TDIC)方法。按照功率控制的实际要求,提出了符合功率控制要求的二次型性能指标定义,得到了最优状态反馈控制器的设计方法。通过系统仿真实验,与其它的改进功率控制算法相比较,证明了所提出的算法具有较强的收敛性和鲁棒性。最后,论文基于复杂网络理论分析了无线网络的拓扑结构。说明了相比于现有的无线网络随机模型,小世界模型和无标度模型更能反映实际无线网络拓扑的特点。针对网络中实际能够测量出的只有部分状态变量或输出量这一特点,分别提出了基于降维观测器的拓扑辨识和基于输出量的拓扑辨识方法,利用部分状态变量或输出量作为反馈控制量,使得通过观测到的部分状态变量和节点输出量就能辨识网络拓扑。进一步考虑了网络中各个节点之间存在传输时延和节点动态特性不一致的情况,并从理论上证明了论文所提出方法的适用性。针对基于复杂网络建模的小型无线Ad hoc网络拓扑,通过大量仿真实验说明了本文提出的辨识方法是有效的。更多还原

【Abstract】 With the development of wireless networks, the communication quality requirements from users are increasing. The link transmission control such as frequency hopping (FH) and power control technology can increase the network capacity and improve the performance in jamming environment. Network topology identification is significant to improve multimedia streaming transmission quality in Ad hoc network. Some new ideas and methods for FH transmission, power control and network topology identification are provided from the perspective of control theory based on state feedback control.Firstly, the frequency hopping technology based on chaos and state feedback control is studied. A kind of chaotic sequence non-periodic self-perturbation method is proposed on DSP in order to overcome the finite precision effect.In the chaotic FH synchronization scheme, a new nonlinear feedback function and genetic algorithm based nonlinear feedback control method are proposed. The Logistic map chaotic sequences synchronization under different parameter space are achieved. Experiments and performance analysis show the effectiveness of the proposed methodsSecondly,The time delay and inteference based state space(TDISS) model is proposed for the closed loop power control in the DS-CDMA system. The impact of actual interference, noise and time delay are considered in the model. Additionally, The optimal power control with time delay and interference compensation(OPC_TDIC) method is proposed for the power control system. The quadratic performance is defined to meet the practical requirements of power control.Then, the optimal state feedback controller design is obtained. The strong robustness and good convergence of the proposed algorithm is demonstrated by the simulation, in comparison with some other improved power control algorithms.Finally, the topology of wireless network is investigated based on complex network theory. Small world model and scale-free model can reflect the actual characteristics of the wireless network better than the stochastic model. A new method based on the reduced-order observer or the output is proposed to identify complex dynamical networks, in which only some state viariables or the output as feedback can be measured. The network topology can be identified through the node output and the observed state variables. Furthermore, the network with time delay and different nodes is taken into account in this proposed simple technique.A large number of simulation results in the small wireless Ad hoc network based on complex network topology confirm the effectiveness of the methods.更多还原